全固态电池仿真模型搭建

This paper studies the state estimation of a solid-state battery. Partial differential equations based on a nonporous insertion model are presented to model the solid state battery. Two assumptions simplifying the battery model under-lie the study of state estimation: that the Li-ion concentration in the solid electrolyte is uniform and the charge transfer coefficient at the positive electrode is 0.5. The assumptions made resolve the issue of very weak observability: the diffusion dynamics in the electrolyte and positive electrode are connected via Butler-Volmer equation and the contribution of the charge transfer overpotential is found to be insignificant. For state estimation, an extended Kalman filter (EKF) is applied based on the simplified battery model using measurements of current and voltage of the cell. Simulation results show that the state-of-charge (SOC) of the battery can be accurately estimated by the EKF in specific SOC ranges, i.e., SOC <0.2 and SOC >0.4.

In all‐solid‐state batteries (ASSBs), the mechanical stress generated during electrode (de)lithiation plays a critical role in determining the cell longevity because of the induced degradation mechanisms. This stress originates from local volume fluctuations in the active electrode materials, such as nickel‐rich LiNixMnyCozO2, which are intrinsically coupled to spatial variations in lithium‐ion concentration during electrochemical cycling. Herein, a novel ASSB model that considers electrochemistry and solid mechanics in a one‐way coupled manner is presented. The model spatially resolves 3D‐microstructure of an ASSB half‐cell generated from wet manufacturing process simulations and is based on linear continuum mechanics. The coupling of electrochemistry and solid mechanics is incorporated via lithiation‐dependent volumetric changes of the active material and the microstructural changes due to deformed geometries affecting the particles percolation paths. Furthermore, it is shown that the overall volume change of the half‐cell is dependent on the C‐rate and on the applied stack pressure. Finally, the findings demonstrate that solid‐mechanical effects and their interplay with electrochemical phenomena significantly impact the evolution of interfacial surface area and the total pore volume. These factors are crucial for ensuring accurate computational predictions, underscoring the necessity of incorporating such interactions in battery modeling approaches.

The thermal behavior is pivotal to the performance and safety of battery cells. To date, several thermal modeling approaches for lithium-ion batteries with liquid electrolyte (LiB) exist for different cell formats, tab designs, and more [1,2]. However, for all-solid-state batteries (ASSBs), relatively few publications exist on this topic. This presentation deals with sulfide-based ASSB cells. Although lab-sized ASSB cells perform well, cycling conditions in the lab still differ from practical applications. On the one hand, high pressure of several tens of MPa is usually applied during cycling to achieve good electrochemical behavior. On the other hand, separator thicknesses are in the range of several hundred µm due to difficulties in production and processability [3]. This results in low energy densities and prevents real-world application [4]. Therefore, a direct comparison between lab-sized ASSB cells and existing LiB cells used in applications is neither reasonable nor possible. Today, it is still impossible to conclude whether ASSBs are truly superior to LiBs. To enable such a comparison, simulation techniques must be applied. Simulation-based upscaling of lab-sized ASSB cells to practical applications allows a fair comparison with LiBs. In this work, the thermal behavior of ASSB cells was investigated as a first step. A novel cell holder for calorimetric measurements of a lab-sized ASSB cell was developed. This cell holder allows for measurement of the heat generation of an ASSB cell in a commercial calorimeter (TAM IV, TA Instruments) while applying pressures of up to 30 MPa. By determining the thermal inertia of the cell holder and using a deconvolution algorithm [5], the original heat signal of the cell can be restored. After introducing the novel cell holder, measurement results of an ASSB cell (LiIn|LPSCl|LPSCl-NMC, 3.0 mAh) will be presented. This includes pressure-dependent results for 0.2 MPa, 10 MPa, 20 MPa, and 30 MPa, C-rates of 0.1C, 1C, and 4C, and temperatures of 25°C, 60°C, and 80°C. These data are crucial to determine the pressure-dependent interfacial resistances as well as the temperature-dependent ionic conductivity and electrochemical behavior of the cell. Furthermore, changes in stack pressure are tracked by a load cell. These results can later be used for mechanical simulations. The cell holder’s measurement results serve as input parameters for the thermal simulation. Different upscaled cell formats are investigated using parameters from the lab-sized cell. Thermal gradients and hotspots within the upscaled cells are identified and compared to LiBs. However, as the cell parameters are still unrealistic for practical applications - with a LiIn anode and a separator thickness of approximately 400 µm - these parameters are altered, starting from the validated lab-sized pouch cell. The thick separator dominates the averaged thermal parameters: heat capacity, thermal conductivity, and density of the cell. Assuming a thin separator of 20 µm leads to a 110% and 50% increase in thermal conductivity and density, respectively, but to a decrease in heat capacity of about 7%. This results in more heating of the cell but fewer thermal gradients. Furthermore, an electrochemical p2D model is parametrized and validated using the measured cycling data and the heat generation curve. Starting from the validated model, application-relevant separator thicknesses and a Li-metal anode are assumed. Lower overpotentials induced by the thinner separator lead to reduced heat generation. However, due to the reduced heat capacity, more cooling power is needed to minimize the heating of the cell. The p2D model is coupled with a thermal 3D model for different sizes and cell formats. Cooling strategies such as convective and tab cooling are compared in terms of effectiveness and electrochemical cell performance. Furthermore, the pressure-dependent measurement data are used to scale the performance for realistic pressure scenarios. Finally, an outlook is given on the thermal safety and runaway behavior of ASSBs. The simulation results enable a fair and realistic comparison of today’s LiBs with future sulfide-based ASSB technologies. Electrochemical behavior, the effort required for cooling strategies, and the resulting overall energy densities serve as indicators for the current progress in ASSBs and the further research necessary to transition ASSBs from laboratory research to real-world applications. Acknowledgment: This work was financially supported by the German Federal Ministry of Education and Research (BMBF) under grant number 03XP0597B (FB2-SAFE). The project is overseen by Project Management Juelich (PTJ). References: [1] Frank et al. ECS Adv. 1 (2022) 40502. [2] Sturm et al. J. Electrochem. Soc. 167 (2020) 130505. [3] Rosner et al. Adv. Energy Mater (2025) 2404790 [4] Schmaltz et al. Adv. Energy Mater (2023) 13, 2301886 [5] Kunz et al. J. Electrochem. Soc.169 (2022) 080513 Figure 1

All Solid-State Batteries (ASSB) have emerged as a promising technology for electric vehicles and portable devices, offering multiple advantages over traditional liquid electrolyte batteries, such as improved safety, longer lifespan and higher energy density (Alabdali et al., 2022, Current Opinion in Electrochemistry , 36 , p.101127). However, as the battery manufacturing industry seeks to make these technologies more affordable, efficient and sustainable, there is an increasing pressure to optimize the use of costly materials like lithium. Battery performance is highly sensitive to design parameters such as electrolyte-domain and cathode thickness, and optimizing these parameters is crucial to both reducing material costs and improving battery performance. Traditionally, finding the optimal values for these design parameters has relied on an experimental trial-and-error approach, which can be both time-consuming and expensive. Therefore, more refined, data-driven methods (Zou et al., 2024, Energy and AI , 18 , p.100451) are needed to achieve cost-effective and high-performance solid-state batteries. In a battery, various physical phenomena govern its performance, particularly the movement of ionic species and charge transfer processes. The Nernst-Planck equation describes the diffusion and migration of ions in the electrolyte, while the diffusion of intercalated atoms within the electrode is governed by the diffusion equation. The Butler-Volmer equation models the charge transfer kinetics at the electrode-electrolyte interface. These processes are also associated with various sources of internal resistances within the battery. For instance, the charge-transfer overpotential arises from resistance to electron movement at the electrode-electrolyte interface. The mass transfer resistance refers to resistance encountered by ions as they move between the electrolyte and the electrode, while the diffusion resistance is the resistance due to the limited speed of ion diffusion in the cathodes (Danilov et al., 2010, Journal of the Electrochemical Society , 158 (3), p.A215). For efficient functioning of the battery the internal resistances should be minimal. In order to investigate the influence of various design parameters on the battery performance, we develop a machine learning (ML) based classifier model trained on the battery simulation data, obtained from the cell-level physics based model. The features considered in the ML model include design parameters such as the electrolyte thickness, cathode thickness and area of cross-section etc. The output of the model is the class into which the battery can be categorized. The battery class is determined by the number of system-level performance attributes (such as energy density, discharge time, various resistances occurring within the battery, etc.) that outperform their predefined expected cut-off values. This metric, therefore, captures the system-level performance attributes of the battery relative the expected values. Batteries part of the highest class correspond to batteries having the optimized range of the design parameters. Using this approach, we can estimate the range of design parameters that would place the battery within that class (inverse design approach). From our hybrid model, we found that a thinner electrolyte thickness, an optimal range of cathode thickness and a larger contact area of solid electrolyte-cathode gives the most efficient batteries. Using this model, one can even predict the class of a battery (based on its system-level performance) from its design parameters. Data-driven approaches like these combine both cell-level physics and machine learning models to train the model using data obtained from cell-level model while incorporating the underlying physical processes occurring within the cell. Our approach helps in new predictions by coupling both models, reducing computation time and providing more reliable, accurate solutions.

No abstract available

All-solid-state lithium batteries offer superior energy density and safety features, making them highly attractive for electric vehicles and wearable devices. Original physics-based electrochemical model can effectively simulate the internal electrochemical reactions, but they are difficult to be applied to embedded battery management systems. To facilitate the development of real-time applications based on physical models, this paper proposes a SOC prediction method based on a simplified electrochemical model (SEM). First, the transcendental transfer function is converted to third-order transfer functions using the Padé approximation. The electric field in the mass transfer overpotential is then solved for using average numerical integration method. Then, the proposed SEM method under variable load conditions is verified by comparing to the results from original partial differential equations. The results show that the developed SEM strikes a balance between high fidelity and computational efficiency. By taking into account the concentration of Li+ ions in the solid electrolyte, the estimation accuracy of SOC in the range of 0.1 to 0.3 is significantly improved, compared with prior studies. Strong support is provided for the advanced control design of smart management systems of ASSBs.

Solid-state batteries have been widely studied due to their unique advantages such as high mechanical strength, good temperature adaptability, and long cycle life. However, the coupling effect of external pressures and ambient temperatures on the cycle performance of solid-state batteries has not been systematically evaluated. Based on the finite element simulation, this work establishes a temperature-pressure-electrochemical coupling model to assess the coupling effect of temperature and pressure on the cycle capacity decay of solid-state batteries. Taking an NMC811-Li6PS5Cl-Li/In solid-state battery as an example, the results show that the optimal pressure range of the battery is 127.38 MPa-254.76 MPa. Applying external stress to a solid-state battery can significantly reduce its capacity decay rate, 191.07 MPa was selected in the optimal stress interval, ten cycles of charge-discharge cycle experiment were carried out on NMC811-Li6PS5Cl-Li/In battery at an ambient temperature of 60°C, the tenth turn capacity of this battery only decays to 97.78% of the initial capacity, while the tenth turn capacity of the non-pressure battery decays to 96.57%. The model established in this study provides an effective approach for finding the optimal external pressure range for solid state batteries, which will contribute to the development of batteries with longer cycle life.

In this study, a discrete element method (DEM) that can simulate particle plastic deformation, sintering, and electrode compaction of all-solid-state batteries was developed. The model can simulate elastic, plastic, and viscoelastic deformations that occur particularly in mold compaction processes. When the stress exceeds the yield strength of the material, inelastic deformation occurs, which can be described by either a plastic or viscoelastic response. We applied this model to simulate mold compaction of an All-Solid-State Battery (ASSB) electrode. This study implements the following novel features:• The model was derived from the Maxwell viscoelastic model and enabled the simulation of the elastic, plastic, and viscoelastic deformation of particles in a mold.• Particle deformation and sintering are modelled by the rate expression of the equilibrium overlap.• The area and spring factors are introduced to account for numerical issues when the porosity approaches zero.

Abstract The micromorphology of composite cathodes is known to play a vital role in determining all‐solid‐state battery (ASSB) performance. However, much of our current understanding is derived from empirical observations, lacking a deeper mechanistic foundation. The “rocking chair” concept of battery chemistry requires maintaining charge neutrality, emphasizing the necessity of examining electrode micromorphology from the perspective of conductive networks. This study systematically investigates the microscopic electrochemical impacts of conductive network micromorphology by varying the Li+‐to‐e− channel ratio in cathodes comprising LiNbO3‐coated LiNi0.8Co0.1Mn0.1O2, Li6PS5Cl, and carbon fibers. Utilizing multiscale synchrotron‐based spectro‐microscopy, we unravel that unbalanced Li+ and e− conducting channels intensify charge polarization within active cathode particles and accelerate their degradation. A further model system with X‐ray nano‐tomography resolved e− and Li+ channels indicates that spatially uniform and well‐paired Li+ and e− conducting channels are highly desirable as they could promote more uniform lithiation/delithiation, mitigating microscopic electrochemical polarization. Electrode‐scale X‐ray holotomography analysis reveals that the impact of conductive networks is particle‐size‐dependent, with smaller cathode particles being more significantly affected. These findings provide mechanistic insights into the interplay between conductive networks and all‐solid‐state battery operation, laying the groundwork for rational design and optimization of cathode architectures in future solid‐state battery technologies.

In the present study a semi-physical two step modeling approach [1] is employed in order to analyze the impact of thickness and microstructure on the energy and power density of an all-solid-state battery. The model considers all performance limiting loss processes such as charge transfer reaction, charge transport and solid-state diffusion. The first step involves the development of a physicochemically motivated impedance model based on the TLM-approach [1, 2]. The model is parameterized through a comprehensive analysis of an all-solid-state (ASSB) battery cell featuring a LNO coated LCO - LGPS composite cathode with a LPSBr separator and an In-Li anode [3]. Different techniques as tomography, impedance spectroscopy and conductivity measurements were performed in order to determine highly reliable model parameters. In the second step a transformation of the simulated impedance spectra from the frequency domain into a time domain model [1, 4] is conducted. Subtracting the electrode and separator overpotentials from the open circuit voltage allows the prediction of the cell voltage during discharge at various C-rates. Model reliability is demonstrated by validation against measured impedance spectra and discharge curves. Through a variation of cell design parameters as particle size, volume fractions and electrode thickness, their effect on the electrode impedance / distribution of relaxation times and the discharge curves is studied in detail. The gravimetric energy and power density, which are both crucial aspects for the battery development, can be directly obtained from these simulations and are both strongly influenced by the cell design parameters. An optimized cell design identified through a detailed sensitivity analysis facilitates an improvement of the energy and power density of around one order of magnitude. References: [1] P. Braun, C. Uhlmann, M. Weiss, A. Weber and E. Ivers-Tiffée, J. Power Sources, 393 , 119 (2018). [2] F. Kullmann, M. Mueller, A. Lindner, S. Dierickx, E. Mueller and A. Weber, J. Power Sources, 587 , 233706 (2023). [3] S. Hori, R. Kanno, X. Sun, S. Song, M. Hirayama, B. Hauck, M. Dippon, S. Dierickx and E. Ivers-Tiffée, J. Power Sources, 556 , 232450 (2023). [4] J. P. Schmidt, P. Berg, M. Schönleber, A. Weber and E. Ivers-Tiffée, J. Power Sources, 221 , 70 (2013).

All-Solid-State Batteries (ASSBs) offer enhanced safety and higher energy density compared to conventional Lithium-Ion Batteries (LiBs), but their thermal management is challenging due to time-varying thermal properties. The thermal behavior of ASSBs is modeled by five Ordinary Differential Equations (ODEs) representing the temperatures of the case surface (near the cathode and anode), cathode, electrolyte, and anode. These temperatures are driven by heat from the battery, derived from an electrochemical model using two Partial Differential Equations (PDEs) for Li+ ions concentration. This study presents an adaptive observer that adjusts thermal conductivities in real-time, accurately estimating ASSB temperatures. Simulations demonstrate that the observer effectively tracks time-varying conductivities, with estimation errors converging to zero and improving thermal management accuracy.

Stresses resulting from electrode material chemomechanics are strongly coupled to solid electrolyte-electrode interface failures. Such failures are significant barriers to realization of practical Li metal solid-state batteries (SSBs). Significant research efforts have been devoted to control anode chemomechanical stress. Here we show positive electrode (cathode) chemomechanical stress is also critical at commercially relevant low (e.g., <1 MPa) stack pressures. Using a series of model textured positive electrodes we provide the experimental evidence of the role of positive electrode lattice strain anisotropy during charge/discharge on positive electrode chemomechanics. Our model systems reveal that positive electrode chemomechanics significantly alter Li metal plating and stripping behavior at low stack pressure. We utilize these learnings to build long cycle-life SSBs with practical areal capacity (5 mAh/cm2) operating under a 1 MPa stack pressure and at room temperature. Our findings highlight the importance of controlling positive electrode chemomechanics to realize low stack pressure SSBs. Solid-state batteries typically require high pressure to operate reliably. Here, the authors show that tuning cathode chemomechanics enables stable lithium metal battery cycling at room temperature and low pressure, eliminating the need for interlayers or elevated temperatures.

This article presents a computational method for generating virtual 3D morphologies of functional materials using low‐parametric stochastic geometry models, that is, digital twins, calibrated with 2D microscopy images. These digital twins allow systematic parameter variations to simulate various morphologies, which can be deployed for virtual materials testing by means of spatially resolved numerical simulations of macroscopic properties. Generative adversarial networks (GANs) have gained popularity for calibrating models to generate realistic 3D morphologies. However, GANs often comprise numerous uninterpretable parameters, making systematic variation of morphologies for virtual materials testing challenging. In contrast, low‐parametric stochastic geometry models (e.g., based on Gaussian random fields) enable targeted variation but may struggle to mimic complex morphologies. Combining GANs with advanced stochastic geometry models (e.g., excursion sets of more general random fields) addresses these limitations, allowing model calibration solely from 2D image data. This approach is demonstrated by generating digital twins for the morphology of microstructures in all‐solid‐state battery (ASSB) cathodes. Since the digital twins are parametric, they support systematic exploration of structural scenarios and their macroscopic properties. The proposed method facilitates simulation studies for optimizing 3D morphologies, benefiting not only ASSB cathodes but also other materials with similar structures.

No abstract available

Solid-state electrolytes offer a promising avenue for energy storage in the context of lithium-based batteries, not only from an energy density perspective, but also by eliminating issues such as freezing of the liquid electrolyte at low temperatures and the performance limitations associated with that. In solid-state batteries, solid electrolytes are not only used in separators but are also needed in composite electrodes. However, the transport properties of solid-state battery composites are often investigated at room temperature, while the temperature dependence of effective ion transport as a function of volume fraction remains underexplored. Therefore, this work investigates the effective ionic transport in composites of multiple sulfide-based solid electrolytes with Si/C as the active material, as a function of composition and temperature. Analyzing impedance spectra with a transmission line model, this work reveals changes in activation barrier and with that the temperature dependence of ion transport upon varying the volume ratios. This finding emphasizes the importance of considering the activation energy in solid-state battery design to tailor battery performance to the temperature range of application. Published by the American Physical Society 2024

Recent studies presented the advantages of incorporating solid-polymer-electrolyte (SPE) interlayers in all-solid-state batteries (ASSB). Still, drawbacks regarding cell performance are expected due to additional polymer-related overpotentials. The pseudo-two-dimensional (p2D) physicochemical model is extended to account for Li-ion transport in the SPE interlayer and in the ceramic LLZO solid electrolyte (SE), as well as for the charge transfer at the SPE|LLZO interface using Butler-Volmer type kinetics. The overpotential analysis for a reference parameterization disclosed a dominant overpotential contribution from the SPE|LLZO charge transfer and a facilitation with increasing discharge C-rate. Variance-based global sensitivity analyses demonstrate that as the exchange current density between SPE and LLZO increases, polarization losses exhibit an exponential-like reduction. Additionally, the radius of the active material particles within the composite cathode exerts a significant and dominant influence on cell performance. With an optimization of the SPE|LLZO exchange current density, the accessible capacity could be increased compared to the reference parameterization from 41% to 61% for a 2C discharge.

The composite cathode consisting of garnet-type solid-electrolyte Li7La3Zr2O12 (LLZO) and active material LiCoO2 (LCO) is one of the most promising solutions for the cathode design of all-solid-state lithium batteries. The transport properties of Li within the LLZO-LCO composite cathode are known to be sensitively dependent on the composition and microstructural features. This study focuses on computationally refining the performance of solid-state batteries by modifying the porosity and volume fractions of the LLZO-LCO composite cathode while considering the variations in the microstructural features. Various 2D and 3D microstructures were synthesized using a stochastic stacking particle model and the corresponding effective diffusivity of Li is calculated using a numerical homogenization method, which allows for a systematic assessment of the impact of composition on lithium transport within the microstructure. By identifying the optimal ratio between LLZO and LCO phases and porosity, this research yields crucial insights for improving the performance of solid-state batteries by tailoring the composite cathode. Figure 1: A) An example 3-dimensional microstructure with 20.3% percent vacuum (white space) and 39.25% percent LCO (yellow) and 40.45% LLZO (orange). B) The highest effective diffusivity (purple) is found when the LLZO percentage is highest. Once the vacuum percentage is 30% or higher, minimal effective diffusivity (red) is observed. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Figure 1

All‐solid‐state batteries (ASSBs) have become an important technology because of their high performance and low‐risk operation. However, the high interface resistance and low ionic conductivity of ASSBs hinder their application. In this study, a self‐developed electrochemical model based on an open‐source computational fluid dynamics platform is presented. The effect of contact area reduction at the electrode/solid‐state electrolyte interface is investigated. Then, a new conceptual 3D structure is introduced to circumvent the existing barriers. The results demonstrate that the discharge time is shortened by over 20% when the area contact ratio reduces from 1.0 to 0.8 at 1 C‐rate, owing to the increased overpotential. By adopting the new 3D pillar design, the energy density of ASSBs can be improved. However, it is only when a 3D current collector is contained in the cathode that the battery energy/power density, capacity, and material utilization can be greatly enhanced without being limited by pillar height issues. Therefore, this work provides important insight into the enhanced performance of 3D structures.

No abstract available

Solid-state batteries (SSBs) present a promising advancement in energy storage technology, with the potential to achieve higher energy densities and enhanced safety compared to conventional lithium-ion batteries. However, their commercialisation is hindered by technical limitations and fragmented research efforts that predominantly focus on materials or individual performance parameters. This narrow scope limits SSB design and optimisation, potentially delaying the transition to commercial cells. Addressing these challenges requires a systematic framework that integrates key design and performance considerations. This study introduces a modelling framework that addresses these challenges by offering a systematic approach to SSB design. The model streamlines the design process by enabling users to define material selections and cell configurations while calculating key performance indicators (KPIs), such as energy density, power density, and resistance, as well as the specifications required for cell manufacturing. A material compatibility validation feature ensures appropriate selection of anode, cathode, and electrolyte materials, while an integrated sensitivity analysis (SA) function identifies critical design parameters for performance optimisation. The model’s accuracy and applicability were validated through comparisons with experimental data, established design frameworks, and the reverse-engineering of commercial SSB prototypes. Results show that the model predicts energy densities within a ±4% deviation in most cases. Additionally, the application of SA highlights its effectiveness in refining design parameters and optimising cell configurations. Despite certain limitations, the model remains a valuable tool in the early stages of battery concept development. It offers researchers and industry professionals a practical means to assess the feasibility of SSB designs and support future scale-up and industrialisation efforts.

Characterizing the microstructure of all-solid-state batteries (ASSBs) during fabrication and operation is vital for their advancement, particularly as scaling to pouch cell levels introduces challenges in probing large-scale microstructural evolution. This work highlights the potential of synchrotron X-ray micro-computed tomography (sXCT) as a nondestructive, rapid (<30 min), and high-resolution technique for visualizing and quantifying key microstructural features, including overhang, porosity, contact loss, active surface area, and tortuosity, in all-solid-state pouch cells. The large field of view (up to millimeters) of sXCT enables detailed analysis at an industry-relevant scale, bridging the gap between laboratory research and commercial applications. Furthermore, integrating realistic sXCT-derived 3D models into multiphysics simulations could provide insights into chemo-mechanical degradation, particularly at the edges of the pouch cells, offering a pathway for designing robust, high-performance ASSBs. This perspective establishes sXCT as an indispensable tool for advancing both the understanding and the engineering of next-generation energy storage systems.

All-solid-state lithium batteries (ASSLBs) are prepared using garnet-type solid electrolytes by quick liquid phase sintering (Q-LPS) without applying high pressure during the sintering. The cathode layers are quickly sintered with a heating rate of 50-100 K min-1 and a dwell time of 10 min. The battery performance is dramatically improved by simultaneously optimizing materials, processes, and architectures, and the initial discharge capacity of the cell with a LiCoO2 -loading of 8.1 mg reaches 1 mAh cm-2 and 130 mAh g-1 at 25 °C. The all-solid-state cell exhibits capacity at a reduced temperature (10 °C) or a relatively high rate (0.1 C) compared to the previous reports. The Q-LPS would be suitable for large-scale manufacturing of ASSLBs. The multiphysics analyses indicate that the internal stress reaches 1 GPa during charge/discharge, which would induce several mechanical failures of the cells: broken electron networks, broken ion networks, separation of interfaces, and delamination of layers. The experimental results also support these failures.

Ion transport and degradation at the solid-electorlyte/cathode interfaces dictate the performance of all solid-state batteries. For example, it has been routinely observed that in many superionic oxide conductors, Li-ion transport kinetics are orders of magnitude slower at the interfaces, such as grain boundaries or interfaces with common electrode materials, compared to the bulk phases. Upon electrochemical cycling, interdiffusion and/or electrolyte/cathode decomposition at these interfaces can further deteriorate Li-ion transport kinetics. Therefore, the ability to understand, predict and precisely control ion transport kinetics and the degree of interfacial degradation are critical and would have a transformative impact on the development of solid-state battery technologies for practical applications. Here I will address the need of a multiscale and multiphysics modeling framework to understand Li-ion transport mechanisms at complex interfaces and predict the kinetics of Li-ion transport in solid-electrolyte/cathode composite architectures that are relevant for all solid-state Li batteries. I will also emphasize the importance of using a closely coupled theory-experiment approach to reveal the atomic details of the interfaces and unravel the degradation mechanisms of interfaces and its impact on Li-ion transport. I will use the garnet-type solid-state electrotype and lithium cobalt oxide cathode as an example to demonstrate the predictive power of such a multiscale, multiphysics modeling framework towards establishing the correlations between ion transport and local atomic structure, chemical environment, and mesoscopic microstructure features in the cathode/electrolyte composites. This work was sponsored by the Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. An award of computer time was provided by the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357.

The safety and energy density of solid-state batteries can be, in principle, substantially increased compared with that of conventional lithium-ion batteries. However, the use of solid-state electrolytes instead of liquid electrolytes introduces pronounced complexities to the solid-state system because of the strong coupling between different physicochemical fields. Understanding the evolution of these fields is critical to unlocking the potential of solid-state batteries. This necessitates the development of experimental and theoretical methods to track electrochemical, stress, crack, and thermal fields upon battery cycling. In this Perspective, we survey existing characterization techniques and the current understanding of multiphysics coupling in solid-state batteries. We propose that the development of experimental tools that can map multiple fields concurrently and systematic consideration of material plasticity in theoretical modeling are important for the advancement of this emerging battery technology. This Perspective provides introductory material on solid-state batteries to scientists from a broad physical chemistry community, motivating innovative and interdisciplinary studies in the future.

Anode‐free all solid‐state batteries (AF‐ASSBs) employ “empty” current collector with three active interfaces that determine electrochemical stability; lithium metal – Solid electrolyte (SE) interphase (SEI‐1), lithium – current collector interface, and collector – SE interphase (SEI‐2). Argyrodite Li6PS5Cl (LPSCl) solid electrolyte (SE) displays SEI‐2 containing copper sulfides, formed even at open circuit. Bilayer of 140 nm magnesium/30 nm tungsten (Mg/W‐Cu) controls the three interfaces and allows for state‐of‐the‐art electrochemical performance in half‐cells and fullcells. AF‐ASSB with NMC811 cathode achieves 150 cycles with Coulombic efficiency (CE) above 99.8%. With high mass‐loading cathode (8.6 mAh cm−2), AF‐ASSB retains 86.5% capacity after 45 cycles at 0.2C. During electrodeposition of Li, gradient Li‐Mg solid solution is formed, which reverses upon electrodissolution. This promotes conformal wetting/dewetting by Li and stabilizes SEI‐1 by lowering thermodynamic driving force for SE reduction. Inert refractory W underlayer is required to prevent ongoing formation of SEI‐2 that also drives electrochemical degradation. Inert Mo and Nb layers likewise protect Cu from corroding, while Li‐alloying layers (Mg, Sn) are less effective due to ongoing volume changes and associated pulverization. Mechanistic explanation for observed Li segregation within alloying LixMg layer is provided through mesoscale modelling, considering opposing roles of diffusivity differences and interfacial stresses.

All-solid-state batteries (ASSBs) working at room and mild temperature have demonstrated inspiring performances over recent years. However, the kinetic attributes of the interface applicable to the subzero temperatures are still unidentified, restricting the low-temperature interface design and operation. Herein, a host of cathode interfaces are constructed and investigated to unlock the critical interface features required for cryogenic temperatures. The unstable interface between LiNi0.90Co0.05Mn0.05O2 (Ni90) and Li6PS5Cl (LPSC) sulfide solid electrolyte (SE) results in unfavorable cathode-electrolyte interphase (CEI) and sluggish lithium-ion transport across the CEI. After inserting a Li2ZrO3 (LZO) coating layer, the activation energy of the Ni90@LZO/sulfide SE interface can be reduced from 60.19 kJ mol-1 to 41.39 kJ mol-1 owing to the suppressed interfacial reactions. Through replacing the LPSC SE and LZO coating layer by the Li3InCl6 (LIC) halide SE, both a highly stable interface and low activation energy (25.79 kJ mol-1) can be achieved, thus realizing an improved capacity retention (26.9%) at -30 °C for the Ni90/LIC/LPSC/Li-In ASSB. Moreover, theoretical evaluation clarifies that cathode/SE interfaces with high ionic conductivity and low energy barrier are favorable to the Li+ conduction through the interphase and the Li+ transfer across the cathode/interphase interface. These critical understandings may provide guidance for low-temperature interface design in ASSBs.

No abstract available

All-solid-state batteries (ASSBs) are safe, high-energy-storage systems. However, despite the progress achieved in the development of high-ionic-conductivity solid electrolytes (SEs), the power performance of ASSBs remains low because of the high interfacial impedances in composite cathodes. Therefore, understanding the interfacial factors is crucial for obtaining high power ASSBs. This study provides a quantitative analysis of the influence of these factors using impedance spectroscopy measurements, which enables the elucidation of the interfacial impedance values of two key parameters, the grain-boundary resistance (ri,gb) and charge-transfer resistance (ri/e). Systematic investigation revealed an unexpected increase in the cathodic resistance with the decrease in the size of the cathode active material (CAM) particles, indicating that even high-reaction-surface-area CAMs yield low ri/e but high ri,gb values owing to their high porosity, resulting in a trade-off relationship. In contrast, this phenomenon is unlikely to occur in liquid-electrolyte-based batteries. Notably, we discuss how composite cathode design impacts performances of stable, high-power, and high-energy ASSBs.

Solid-state electrolytes (SSEs) are promising alternatives to conventional liquid organic electrolytes in lithium-ion batteries (LIBs), primarily due to their non-flammability and potential to reduce battery size. SSEs are categorized into three types: solid polymer electrolytes (SPEs), inorganic ceramic electrolytes (ICEs), and composite solid electrolytes (CSEs). Solid polymer electrolytes (SPEs) offer good interface contact with electrodes but suffer from low ionic conductivity and poor mechanical stability. In contrast, inorganic ceramic electrolytes (ICEs) exhibit high ionic conductivity and excellent mechanical stability but have weak electrode contact due to stiffness. Composite solid electrolytes (CSEs) aim to combine the advantages of both SPEs and ICEs, utilizing inorganic filler and polymer host to enhance conductivity, mechanical stability, and electrode contact. Understanding the mechanisms behind the enhanced ionic conductivity of CSEs is important to getting the key. Previous studies have investigated various factors, including the type and morphology of fillers, with active fillers showing promise in improving conductivity by facilitating extra Li-ion transport and maintaining the amorphous phase of the polymer. However, the exact cause of enhanced conductivity remains unclear. This study proposes the use of ionic liquids to exclude the amorphous effect of polymers and compares the ionic conductivity with active fillers. Additionally, nanoparticles are introduced to form a solid phase without additional solvents, enhancing filler-polymer contact and promoting thixotropy in the electrolyte, which improves safety and stability. To investigate the interphase effect between filler and matrix, our study focuses on controlling the vacancy concentration on the filler surface using garnet-type oxide as the filler material. X-ray photoelectron spectroscopy (XPS) analysis reveals a difference in oxygen vacancy (O-v) concentration between raw material and filled powder, indicating the influence of surface vacancies on ionic conductivity. Experimental results show that the addition of fillers increases the ionic conductivity of electrolytes, with lower oxygen vacancy concentrations leading to higher ionic conductivity. Distribution of relaxation time (DRT) analysis indicates low resistance in the electrolyte at most timescales, especially showing low diffusion resistance, suggesting improved ion transport properties. COMSOL Multiphysics simulations prove consistent electrolyte current density from the whole electrolyte, inducing uniform ion flux to electrodes. Laser-induced breakdown spectroscopy (LIBS) and XPS depth profiles confirm thin and uniform growth of the solid electrolyte interphase (SEI) layer, contributing to cycle stability. Overall, our study provides insights into the role of surface-controlled fillers in enhancing electrochemical properties and understanding ion-conduction mechanisms in composite solid electrolytes (CSEs). We explore the interphase effect between filler and matrix using Li conductive oxide. Vacancies on the filler surface impact electrolyte properties; fewer vacancies correlate with improved ionic conductivity and stability. Results show enhanced conductivity in surface-controlled electrolytes compared to host or composite electrolytes. Oxygen-filled electrolytes demonstrate superior thermal and electrochemical stability, promoting uniform SEI layer formation and enhancing specific capacity and cycle stability in Li metal half-cells. These findings contribute to developing safer, more efficient solid-state batteries for various applications. Figure 1

All solid‐state batteries are promising, as they are expected to offer increased energy density over conventional lithium‐ion batteries. Here, the microstructure of solid composite electrodes plays a crucial role in determining the characteristics of ionic and electronic pathways. Microstructural aspects that impede charge carrier transport can, for instance, be voids resulting from a general mismatch of particle sizes. Solid electrolyte materials with smaller particle size distribution represent a promising approach to limit the formation of voids and to match the smaller active materials. Therefore, a systematic investigation on the influence of the solid electrolyte particle size on the microstructural properties, charge carrier transport, and rate performance is essential. This study provides an understanding of the influence of the particle sizes of Li6PS5Cl on the charge carrier transport properties and their effect on the performance of solid‐state batteries. In conclusion, smaller Li6PS5Cl particles optimize the charge transport properties and offer a higher interface area with the active material, resulting in improved solid‐state battery performance.

No abstract available

Simulation models are nowadays indispensable to efficiently assess or optimize novel battery cell concepts during the development process. Electro-chemo-mechano models are widely used to investigate solid-state batteries during cycling and allow the prediction of the dependence of design parameters like material properties, geometric properties, or operating conditions on output quantities like the state of charge. One possibility of classification of these physics-based models is their level of geometric resolution, including three-dimensionally resolved models and geometrically homogenized models, known as Doyle-Fuller-Newman or pseudo two-dimensional models. Within this study, the advantages and drawbacks of these two types of models are identified within a wide range of the design parameter values. Therefore, the sensitivity of an output quantity of the models on one or a combination of parameters is compared. In particular, the global sensitivity, i.e., the sensitivity in a wide range of parameter values, is computed by using the Sobol indices as a measure. Furthermore, the local sensitivity of the difference in the output quantities of both models is evaluated to identify regions of parameter values in which they contain significant deviations. Finally, remarks on the potential interplay between both models to obtain fast and reliable results are given.

All-solid-state lithium-ion batteries face challenges in terms of increasing their capacity for high-speed charging and discharging, which will require optimization of the electrode structure. This structure comprises a solid electrolyte (SE) and active material (AM) and the AM particle size is one of the most important factors affecting the structure. The present study examined the effects of AM particle size on electrode structure and performance through discharge experiments, X-ray computed tomography (CT), and pseudo-two-dimensional (P2D) simulations. The SE tortuosity and AM specific contact area diameter (DSCA) used in the P2D simulations were obtained from X-ray CT data and the results of these simulations were verified through a comparison with experimental data. The latter indicated that smaller AM particle sizes provided increased battery performance. The P2D simulations based on DSCA values were found to be highly accurate and showed the same correlation between particle size and performance. These simulations also demonstrated that changes in performance originate from differences in the overpotential associated with lithium diffusion in the AM particles. Specifically, smaller AM particles having lower DSCA values reduce the overpotential associated with lithium diffusion to give improved performance.

This article develops an electromechanical-thermal model for semi-solid-state batteries using Software COMSOL Multi-physics. The battery’s three-dimensional structure is firstly simplified into a one-dimensional electrochemical model (P2D), which combines the solid heat transfer module and the solid mechanics module. The total power consumption of the battery, obtained from the P2D model, is used to calculate the battery temperature and the lithium concentration. Then, stress analysis of the anode active particles is conducted, and the battery temperature is fed back into both the electrochemical and mechanical models. To validate the model, constant current charge/discharge cycling experiments, as well as tests on the basic electrical parameters and temperature of the battery, are conducted. The electromechanical-thermal model developed in this study serves as an effective tool for simulating semi-solid-state lithium-ion batteries, which can predict the battery’s performance under various operating conditions. The simulation results from the numerical model are consistent with experimental data at low charge/discharge rates, while slightly larger discrepancies are observed at high charge/discharge rates, with the accuracy remaining over 90%. Further, the thermal expansion behavior of the batteries with silicon-carbon anodes during the charge-discharge process can be examined using the developed model.

The present study focuses on the electrochemical-mechanical (ECM) coupling effects of a thin-film, solid-state battery with only stiff, ceramic materials, in contrast to prior investigations that focus on individual active material particles or aggregations of particles. We model the impacts of ECM couplings including stress-transport and stress-equilibrium potential on the full-cell performance and potential mechanical failure modes of a thin-film battery conformally deposited in a nanopore scaffold, which is an experimentally achievable device. Model results indicate electrode volume changes due to lithium insertion or removal, along with mechanical boundary conditions, result in stress gradients that alter the lithium-ion flux, reduce lithium concentration gradients, and improve cell rate capability. However, the high stress levels in the cell can also lead to mechanics-related failure such as the separation of cell layers. For the parameter set in this work, stress-transport coupling has a much greater influence on rate capability than stress-potential coupling. Optimization of thin-film batteries to harness the benefits of ECM effects requires leveraging geometric design and material selection. The current work underscores the need for further theoretical and experimental investigation into ECM effects in thin-film batteries to enhance their understanding and design optimization.

Solid-state supercapacitors (SSC) are pivotal in modern energy storage technologies due to their high power density, rapid charge–discharge cycles, and extended lifespan. They can be used in both structural and flexible configurations with innovative applications across industries. For practical applications, SSCs need to preserve their electrochemical performance at elevated service temperatures. Therefore, the interplay and effect of high temperatures on the electrochemical performance of SSCs need to be investigated. In this work, for the first time, a multiphysics thermo-electrochemical coupled continuum modeling framework is developed to capture the effect of temperature on the frequency-dependent behavior of SSCs. This novel approach employs finite element analysis (FEA) instead of conventional equivalent circuit methods, enabling more detailed insights into the internal structure effects of temperature on performance parameters such as resistance, diffusion, and double-layer capacitance. The model is numerically solved by means of finite element analysis (FEA). To validate the simulations, a sustainable solid-state supercapacitor was fabricated using biocarbon and chemical vapor deposition. The use of biowaste-derived biocarbon as a novel sustainable electrode material aligns with global sustainability goals. The temperature-dependent impedance of the supercapacitor was measured at temperatures within 20 to 50 °C. The results showed that the model is able to predict the cell impedance behavior at various elevated temperatures. Furthermore, a sensitivity study was conducted to examine the effects of various coupling parameters. Key findings reveal the substantial impact of high temperature on resistance, diffusion, and double-layer capacitance. The system response trend was changed at 50 °C due to polymer electrolyte degradation. This thermo-electrochemical framework provides valuable insights for the design and optimization of next-generation solid-state supercapacitors, contributing to the development of sustainable energy storage solutions.

No abstract available

Rechargeable batteries are integral to modern technology, with lithium-ion batteries (LIBs) leading in portable electronics and electric vehicles. However, the abundance and global distribution of sodium have renewed interest in sodium-ion batteries (SIBs) as a sustainable alternative, particularly for stationary energy storage and applications with less stringent energy density needs. This study develops a pseudo-two-dimensional (P2D) model to investigate the performance of all-solid-state sodium-ion batteries (ASSSIBs) with hybrid polymer– ceramic electrolytes. We compare this model with a particle-resolved microstructure model to derive effective transport parameters. Our results highlight the significance of electrolyte composition and cell design to mitigate transport limitation in the electrolyte and maximize battery performance. Optimal cell design varies with C-rate, requiring lower active material fractions and more uneven particle distributions for higher rates. Optimization shows that the charge process can harness more cell capacity than discharging, suggesting a bottleneck in the discharge process. These insights guide the development of more efficient and reliable ASSSIBs, emphasizing the importance of fast-ion conducting solid electrolytes for future advancements.

It is popular to choose the cubic phase Li7La3Zr2O12(c-LLZO) to synthesize the PEO-based complex membrane in all-solid-state battery. In this work, Ba/Nb elements were selected to achieve Li6.75La3Zr1.75Nb0.25O12 (LLZNO) and Li7La2.75Ba0.25Zr1.75Nb0.25O12 (LLBZNO) with high ion conductivity, which effectively enhance the electrochemical properties of the complex solid membrane and the all-solid-state battery. The higher ion mobility of LLBZNO compared to that of LLZNO and LLZO is calculated by ab-initio molecular dynamics (AIMD) simulation and further confirmed by experiments. Results show that the cubic phase of LLBZNO is more stable than that of LLZNO. The complex membrane of LLBZNO@ polyethylene oxide (PEO) (CPE-2-x wt%) exhibits the better electrochemical properties than LLZNO@PEO (CPE-1-x wt%) complex membrane. In detail, the CPE-2-10 wt% has the outstanding lithium transfer number (t_(〖Li〗^+ )) of 0.63, as well as the excellent compatibility with lithium metal anode. In addition, at 0.1 mA∙cm−2, the lithium/CPE-2-10 wt%/lithium symmetric cell remains stable after 1000 h. It is LLBZNO that makes LLBZNO@PEO composite polymer electrolyte(CPE) the potential for the application in all-solid-state lithium battery.

Metal–organic frameworks (MOFs) have been reported as promising materials for electrochemical applications owing to their tunable porous structures and ion‐sieving capability. However, it remains challenging to rationally design MOF‐based electrolytes for high‐energy lithium batteries. In this work, by combining advanced characterization and modeling tools, a series of nanocrystalline MOFs is designed, and the effects of pore apertures and open metal sites on ion‐transport properties and electrochemical stability of MOF quasi‐solid‐state electrolytes are systematically studied. It isdemonstrated that MOFs with non‐redox‐active metal centers can lead to a much wider electrochemical stability window than those with redox‐active centers. Furthermore, the pore aperture of MOFs is found to be a dominating factor that determines the uptake of lithium salt and thus ionic conductivity. The ab initio molecular dynamics simulations further demonstrate that open metal sites of MOFs can facilitate the dissociation of lithium salt and immobilize anions via Lewis acid–base interaction, leading to good lithium‐ion mobility and high transference number. The MOF quasi‐solid‐state electrolyte demonstrates great battery performance with commercial LiFePO4 and LiCoO2 cathodes at 30 °C. This work provides new insights into structure–property relationships between tunable structure and electrochemical properties of MOFs that can lead to the development of advanced quasi‐solid‐state electrolytes for high‐energy lithium batteries.

No abstract available

No abstract available

1School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA 2School of Mechanical Engineering, Purdue University, West Lafayette, IN, 47907, USA 3Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, NM 87545, USA 4Capacitor Foundry, LLC, Thousand Oaks, California, 91320, USA 5School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA 6Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, USA 7Institute for Electronics and Nanotechnology, Georgia Institute of Technology, Atlanta, GA, 30332, USA 8George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA

No abstract available

Dendrite formation in batteries is a critical issue that affects battery performance and lifespan. Solid-state electrolytes have gained attention due to their advantages such as compactness, higher energy density, and enhanced safety. This study investigates dendrite growth in batteries via phase field simulations utilizing a grand potential-based phase field model. The simulations are executed using the MOOSE (Multiphysics Object-Oriented Simulation Environment) framework, a Finite Element Method (FEM) based solver known for its modular approach and proficiency in handling complex multi-physics problems. Initially, the study considers a pure lithium anode and a 1M LiPF6 electrolyte for the liquid case. To explore the benefits of solid electrolytes, a fictitious solid electrolyte with transport properties similar to the liquid electrolyte but having different mechanical properties is considered. The mechanical impact resulting from the volume changes due to lithium deposition is not accounted for in the liquid electrolyte model. However, the solid electrolyte model addresses this by modifying the Butler-Volmer kinetics and incorporating the influence of stresses on the localized lithium deposition. Sensitivity analysis is performed for various parameters in both the liquid and solid electrolytes. The results indicate that dendrite growth is reduced with decreased applied over-potential and interfacial energies. For solid electrolytes, an additional parameter, increased Young’s modulus, contributes to reduced dendrite growth. The evaluation of dendrite growth involves quantifying surface roughness using the root mean square (RMS) approach. The elasticity modulus significantly influences dendrite formation, with higher values in materials like LLZO, and glass Li3PS4 exhibiting lower dendrite growth, while lower values in polymer-based materials like P(VDF-HFP) and PVDF/CAB/PE exhibit higher dendrite growth. The solid electrolyte acts as a crucial mechanical barrier, influencing the dendrite tip growth rate and ensuring uniform electrodeposition throughout the dendritic structure. Furthermore, the work investigates the impact of the cathode on dendrite growth. The contraction of the cathode provides additional space for dendrites to move, leading to reduced compressive stresses and increased dendrite growth. Conversely, higher compressive stresses suppress dendrite growth.

In traditional Li-ion batteries with liquid electrolyte, the transport of lithium ions in the electrolyte and lithium in the active material within a porous electrode are studied extensively. The continuum-scale modeling of these transport phenomena considers a homogenized simulation domain consisting of liquid electrolyte and solid active material with effective transport properties accounting for the heterogeneity [1]. There have been fewer studies that consider digitized versions of the experimentally imaged microstructure in continuum-scale modeling studies, particularly to study mechanics [2]. Despite of the computational challenges, there are inherent advantages in using fully resolved microstructure modeling to improve fundamental understanding of the relevant physical and chemical phenomena in porous electrodes, such as localized degradation and stress concentration. In the case of solid electrolytes, specifically scaffold-type LLZO solid electrolytes, microstructure modeling is of even more relevance, particularly to study anisotropic transport, localized degradation phenomena, stress and deformation leading to loss of contact, and chemo-mechanics. Thus far, microstructure modeling studies on experimentally obtained microstructure consisting of solid electrolyte and active material have been quite limited [3]. The studies that have explored this realm have employed voxel-based mesh to discretize the computation domain [3]. While these methods are sufficient proof of concept, the lack of precision in defining the interface separating active material and electrolyte when using voxel-based mesh provides a source of potentially significant numerical error. Without a highly resolved interface mesh, the total interfacial area increases artificially which leads to inaccuracies in calculations of local reaction rate and overpotential. A highly resolved, smooth interface is also necessary when simulating mechanical deformation and stress field in the microstructure. In the present investigation, we model mass transport and charge transport in the active material/electrolyte microstructure to simulate concentration and potential fields with varying mesh types in order to compare their effectiveness and characterize the error that can be attributed to the mesh type chosen, particularly in the case of voxel-based meshes. Additionally, we study the effect of microstructure domain length chosen in the two directions perpendicular to the shortest length (electrode thickness) as well as boundary condition formulation on the boundaries in these axes on the simulation results. The microstructures studied in this work are derived from the image stacks of the bi/trilayer LLZO solid electrolyte fabricated using freeze-tape-casting method [4]. Overall, the present work aims to develop a better understanding of the best practices in microstructure modeling, particularly when using microstructure image stacks obtained from fabricated samples. References [1] M. Doyle, T.F. Fuller, J. Newman, J. Electrochem. Soc., 140, 1526 (1993). [2] H. Mendoza, S.A. Roberts, V.E. Brunini, A.M. Grillet, Electrochim. Acta, 190, 1 (2016). [3] M. Alabdali, F.M. Zanotto, V. Viallet, V. Seznec, A.A. Franco, Curr Opin Electrochem, 36, 101127 (2022). [4] Hao Shen, Eongyu Yi, Stephen Heywood, Dilworth Y. Parkinson, Guoying Chen, Nobumichi Tamura, Stephen Sofie, Kai Chen, and Marca M. Doeff, ACS Appl Mater & Interfaces, 12, 3494 (2020).

Solid-state batteries are poised to revolutionize the energy landscape, offering higher energy density and improved safety compared to current liquid electrolyte batteries. However, interfacial stability challenges must still be overcome before the most promising materials can become widely accessible. The overwhelming consensus in the literature indicates that existing theoretical frameworks inadequately represent the multifaceted, multiphysics behavior of energy storage materials. While some robust theoretical models exist, most either neglect critical couplings, lack the necessary dimensionality to analyze interfacial stability, or are constrained by their inherent linearity. Moreover, magnetic couplings are almost universally neglected despite groundbreaking experimental evidence demonstrating that properly oriented magnetic fields can significantly enhance interfacial stability. Consequently, nearly all technological advancements rely on experimental trial and error, which is slow, labor-intensive, and expensive. To address these gaps, this work proposes a novel, thermodynamically consistent mathematical framework to analytically describe the behavior of battery materials and their interfaces under the coupled influence of thermal, electrochemical, magnetic, and mechanical fields at the continuum scale. The theory is formulated generally enough to accommodate large displacements in the battery. The resulting constitutive model aligns well with established theoretical approaches from other contexts, yet it allows for additional couplings rarely or never considered in the battery literature, particularly the influence of evolving magnetic fields on ion transport. Critically, this theoretical framework is computationally implemented using the finite element method. Elements are formulated with curl-conforming edge degrees of freedom to interpolate the magnetic potential and standard Lagrangian interpolation for other fields. Additionally, a block preconditioning methodology is adopted to enable robust, fully coupled iterative solutions. This computational approach effectively captures the cross-influence of magnetic fields on electrochemical processes within a battery. As an illustrative example demonstrating the utility of this technology, a charging cycle is simulated on a segment of a solid-state battery cell featuring a sharp dendrite at the lithium anode/separator interface. By observing how the application of a magnetic field alters current concentration at the dendrite tip, the magnetic field strength necessary to stabilize interfaces for varying interfacial geometries can be determined. Thus, the proposed technology enables rigorous, analytical exploration of magnetic influences on battery operations, providing researchers with powerful tools to harness these promising multiphysics phenomena.

Solid‐state Li metal batteries (SSLMBs) offer higher energy density and safety. However, they face significant challenges, particularly short circuits caused by the growth of Li dendrites. The porosity of the electrolyte plays a crucial role in influencing Li‐ions transport, interfacial contact, mechanical strength, and volume energy density of batteries. This study investigates the effects of the electrolyte film porosity on the nucleation of Li metal and the formation of dendrites in sulfide‐based SSLMBs. Surprisingly, the findings reveal that increased electrolyte porosity enhances the electronic conductivity by several times. Density Functional Theory calculations on the surface/bulk phase of electrolyte and the spacing between electrolyte particles indicate that increased surface exposure through porosity reduces the bandgap, enhancing electronic conductivity and thereby facilitating the formation of Li dendrites. The electrochemical simulation results demonstrate that pores create a non‐uniform distribution of Li‐ion concentration, current density distribution, and the electric potential field on the collector and within the electrolyte. Experimental results demonstrate that the electrolyte film with lower porosity exhibits a higher limiting current and superior electrochemical performance. This study contributes to understanding the effect of electrolyte porosity and provides valuable insights for designing high‐performance SSLMBs.

Solid-state polymer electrolytes (SPEs) are emerging as a promising alternative to liquid electrolytes, addressing key challenges such as safety concerns, thermal instability, and dendrite growth while enabling flexible integration into battery designs. However, their widespread adoption is hindered by critical limitations, including low ionic conductivity, narrow operational temperature ranges, and compatibility with electrode materials. To address these challenges, a systematic understanding of the molecular structures, thermal properties, and ion transport mechanisms of SPEs is essential. This study employs a multiscale modeling and simulation approach to investigate carbonate-based SPEs with varying side-chain lengths and small molecular lubricants, comparing them to traditional liquid carbonate electrolytes. Molecular dynamics (MD) simulations are utilized to explore how polymer chain design influences nano-segregation and thermal behavior. By contrasting the nanostructure, thermal dynamics, and lithium-ion transport properties of SPEs with those of liquid electrolytes, such as dimethyl carbonate and ethylene carbonate, this research provides a comprehensive analysis of the factors governing performance. The findings aim to guide the engineering of polymer materials with optimized nanostructures and enhanced lithium-ion transport properties, contributing to the advancement of safer, more efficient battery technologies.

The Li‐metal anode has been recognized as the most promising anode for its high theoretical capacity and low reduction potential. However, the major drawbacks of Li metal, such as high reactivity and large volume expansion, can lead to dendrite growth and solid electrolyte interface (SEI) fracture. An in situ artificial inorganic SEI layer, consisting of lithium nitride and lithium sulfide, is herein reported to address the dendrite growth issues. Porous graphene oxide films are doped with sulfur and nitrogen (denoted as SNGO) to work as an effective lithium host. The SNGO film enables the in situ formation of an inorganic‐rich SEI layer, which facilitates the transport of Li‐ions, improves SEI mechanical strength, and avoids SEI fracture. In addition, COMSOL simulation results reveal that the microchannels fabricated by the 3D printing technique further shorten the Li‐ion transfer pathways and homogenize heat and stress distribution in the batteries. As a result, the assembled anode shows low capacity fading of 0.1% per cycle at 2 C rate with the sulfur cathode. In addition, the high lithium utilization of the SNGO host enables the anode to provide a stable capacity at low negative/positive electrode ratios under 3 in LiS batteries.

Manufacturing advanced solid‐state electrolytes (SSEs) for flexible rechargeable batteries becomes increasingly important but remains grand challenge. The sophisticated structure of robust animal dermis and good water‐retention of plant cell in nature grant germane inspirations for designing high‐performance SSEs. Herein, tough bioinspired SSEs with intrinsic hydroxide ion (OH−) conduction are constructed by in situ formation of OH− conductive ionomer network within a hollow‐polymeric‐microcapsule‐decorated hydrogel polymer network. By virtue of the bioinspired design and dynamic dual‐penetrating network structure, the bioinspired SSEs simultaneously obtain mechanical robustness with 1800% stretchability, good water uptake of 107 g g−1 and water retention, and superhigh ion conductivity of 215 mS cm−1. The nanostructure of bioinspired SSE and related ion‐conduction mechanism are revealed and visualized by molecular dynamics simulation, where plenty of compact and superfast ion‐transport channels are constructed, contributing to superhigh ion conductivity. As a result, the flexible solid‐state zinc–air batteries assembled with bioinspired SSEs witness high power density of 148 mW cm−2, specific capacity of 758 mAh g−1 and ultralong cycling stability of 320 h as well as outstanding flexibility. The bioinspired methodology and deep insight of ion‐conduction mechanism will shed light on the design of advanced SSEs for flexible energy conversion and storage systems.

All-solid-state lithium batteries (ASSBs) have the potential to deliver higher energy and power densities compared to conventional lithium-ion batteries with liquid electrolytes. Due to the use of solid electrolytes, a uniform distribution and close contact between the active material (AM) and solid electrolyte (SE) particles are essential for a proper electrochemical behavior of the electrodes. Thus, understanding the correlation between the microstructure of composite electrodes, charge transport, and cell performance is critical. We present, in this work, a comprehensive computational modeling workflow that examines the influence of the degree of calendering on the final performance of slurry-based composite electrodes. This study uses NMC622/Li₆PS₅Cl-based cathode microstructures with the presence of carbon and binder, generated through conventional calendering, via manufacturing process simulations. This computational workflow is able to correlate the manufacturing process, the composite cathode microstructure and the cell performance, as it combines Coarse-Grained Molecular Dynamics (CGMD) for the manufacturing simulation of the slurry, drying and calendaring [1] with a 4D-resolved performance model describing electrochemistry and transport mechanisms (cf. Figure 1). The three-dimensional spatial locations of AM, SE, and Carbon-Binder Domain (CBD) within the electrode, as predicted from CGMD simulations, are considered explicitly as separated phases, each of them with specific physical properties. Our computational modeling workflow, allowing to perform simulations from the solvent-based manufacturing process to the electrochemical performance of the resulting ASSBs cathodes, permits the study of the impact of the calendering on ionic flux bottlenecks, the heterogeneities of electrochemical reactivity within the electrode volume, and the resulting overall electrochemical performance. These features make our modeling approach a powerful tool to provide guidance for optimized manufacturing of the ASSBs cathodes with wet-processing methods [2]. Figure 1. Schematic of our computational workflow simulating the wet manufacturing process of ASSB composite cathodes: from slurry to calendered electrode followed by the half-cell electrochemical performance simulation. References: Alabdali, M.; Zanotto, F.M.; Duquesnoy, M.; Hatz, A.-K.; Ma, D.; Auvergniot, J.; Viallet, V.; Seznec, V.; Franco, A.A. Three-Dimensional Physical Modeling of the Wet Manufacturing Process of Solid-State Battery Electrodes. Journal of Power Sources 2023, 580, 233427, doi:10.1016/j.jpowsour.2023.233427. Ben Hadj Ali, S.; Alabdali, M.; Viallet, V.; Seznec, V.; Franco, A.A. A Computational Workflow for the Simulation of Solid State Battery Electrodes from Manufacturing to Electrochemical Performance, Journal of Power Sources, 2024 (Under review). Figure 1

Solid electrolytes encompass various types of nanodefects, including grain boundaries and nanovoids at the Li-metal/solid electrolyte interface, where lithium dendrite penetration has been extensively observed. Despite the importance of ion transport near grain boundaries with different anisotropy and the combinatorial effects with interfacial nanovoids, a comprehensive understanding of these phenomena has remains elusive. Here, we develop a chemo-electro-mechanical phase-field model to elucidate how Li penetrates Li7La3Zr2O12 in the co-presence of grain boundaries and interfacial nanovoids. The investigation unveils a grain-boundary-anisotropy-dependent behavior for Li-ion transport correlated with the presence of interfacial nanovoids. Notably, the Σ1 grain boundary exhibits faster Li dendrite growth, particularly in the co-presence of interfacial nanovoids. The model quantitatively reveals whether interfacial electronic properties dominate Li dendrite morphology and penetration, providing a strategy for designing stable Li/solid electrolyte interfaces. These findings help prioritize approaches for optimally tailoring nanodefects and exploiting synergetic effects at the interface to prevent dendrite formation. Grain boundary nanodefects exist in solid electrolytes but detailed factors affecting ion transport are still limited. Here, a chemo-electro-mechanical phase-field model shows how Li penetrates Li7La3Zr2O12 in the co-presence of grain boundaries and interfacial nanovoids

No abstract available

This work presents a comprehensive analysis of a reversible solid oxide cell (SOC) operating in dual mode, which allows for both hydrogen production for electrolysis mode and power generation under fuel cell mode. Employing an analytical model, we explore the dynamic behavior and efficiency of the SOC under varying operational conditions. The model covers several components, including a NiO-YSZ fuel-side support and functional layer, a YSZ electrolyte, a GDC interlayer, and an air-side made up of LSCF+GDC and LSCF. The study highlights the ability to switch between the electrolysis to fuel cell modes, depending on the supply dynamics and energy demand. The model incorporates key electrochemical reactions, ion transport mechanisms, and mass transfer processes, providing detailed insight into the internal functioning of the fuel cell. The model predicts the performance of a single-cell SOC in dual mode using humidified hydrogen with targeted dew points of 81.8°C (50 kPa), 69.1°C (30 kPa), and room temperature (3 kPa) at the fuel side and 21% O2 and 79% N2 at the air-side at different operating temperatures of 700°C, 660°C, 620°C, and 580°C. Experimental validation is conducted to ensure the reliability of the model's predictions, with results showing a strong correlation between the simulated data and observed performances. The findings underscore the potential of dual-mode SOCs in enhancing the flexibility and sustainability of energy systems, particularly in applications where both power and hydrogen are required. The findings suggest that while concentration overpotentials are generally lower, activation and ohmic overpotentials predominantly dictate the overall potential loss in the cell, underlining the importance of minimizing them to boost cell performance. Figure 1

The development of lithium-based solid-state batteries (SSBs) has to date been hindered by the limited ionic conductivity of solid polymer electrolytes (SPEs), where nonsolvated Li-ions are difficult to migrate in a polymer framework at room temperature. Despite the improved cationic migration by traditional heating systems, they are far from practical applications of SSBs. Here, an innovative strategy of light-mediated energy conversion is reported to build photothermal-based SPEs (PT-SPEs). The results suggest that the nanostructured photothermal materials acting as a powerful light-to-heat converter enable heating within a submicron space, leading to a decreased Li+ migration barrier and a stronger solid electrolyte interface. Via in situ X-ray diffraction analysis and molecular dynamics simulation, it is shown that the generated heating effectively triggers the structural transition of SPEs from a highly crystalline to an amorphous state, that helps mediate lithium-ion transport. Using the assembled SSBs for exemplification, PT-SPEs function as efficient ion-transport media, providing outstanding capacity retention (96% after 150 cycles) and a stable charge/discharge capacity (140 mA g-1 at 1.0 C). Overall, the work provides a comprehensive picture of the Li-ion transport in solid polymer electrolytes and suggests that free volume may be critical to achieving high-performance solid-state batteries.

This paper primarily focuses on the formulation and validation of mathematical and numerical models for a new electrolyte-supported solid oxide fuel cell stack. By leveraging numerical modeling, the main goal is to deepen the understanding of the operational aspects and transport phenomena within this system. The developed models are implemented in ANSYS, Inc., Fluent software, which enables a range of simulations. To validate the models, a stack fabrication methodology, a prototype construction, and conducted electrochemical tests were proposed. The simulated current-voltage characteristics for two different operating temperatures and three different fuel compositions were compared with the experimental measurements with satisfactory agreement. The counter-flow configuration was simulated and compared to the co-flow arrangement. The numerical simulation has demonstrated its efficacy in identifying possible design imperfections and enhancing the operational conditions of the prototype stack. Moreover, the developed model was further used, in Part 2 of this paper, to analyze the improvement options implementation for the next stage of the prototype.

Solid oxide electrolysis cell (SOEC) is one of the best candidates for hydrogen production with zero carbon footprint, but cell degradation limits its implementation for long-term application. In this study, a three-dimensional (3D) button cell configuration model is used to study the oxygen electrode (OE) delamination, which is the major cause for the cell degradation during polarization life cycle. A composite lanthanum strontium cobalt ferrite (LSCF) and gadolinium doped ceria (GDC) is used as OE material. From the initial observation by solving for species transport equations for different crack propagation, it was found that cell degradation was largely dependent on relative area cracked at OE/electrolyte (EL) interface and independent of direction or shape of crack propagation. Electrochemical impedance spectroscopy (EIS) from physics-based model under DC bias is implemented to examine closely the electrochemical properties variation with aid of experiment measurement.

In this study, we simulated BZY electrolyte-supported proton-conducting solid oxide cell by coupling surface defect chemistry reaction with charged species transport. We validated the model parameters by concentration as a function of temperature, conductivity under dry and wet oxygen as a function of oxygen partial pressure and temperature. The results indicate that the high electron-hole mobility (diffusivity) is mainly responsible for the high leaking current under high temperatures. The Faradaic efficiency stays low or even negative under low operating voltage or high temperature and plateaus as the cell voltage increases. The model developed in this study is a useful tool to understand the leaking current in BZY electrolyte and provide design strategies to avoid/mitigate such significant inefficiency for water electrolysis operation.

With the growing interest in all-solid-state battery (ASSB) technology for high-energy and high-power applications, the electrochemical performance of cell components and production-related characteristics must be improved to achieve reliable and cost-effective scale-up of laboratory cell concepts [1]. Combining inorganic ceramic and polymer solid electrolytes (SEs) serves to tune the ionic transport and the mechanical properties of composite cathodes [2, 3]. A polymer electrolyte share in the composite cathode is expected to improve the mechanical contact between the cathode active material (CAM) and the SE, resulting in facilitated charge transfer and improved cell performance. Furthermore, polymer SEs serve to overcome the challenges of co-sintering dense composites of CAM and inorganic SE [4, 5]. In hybrid cell concepts with polymer- and inorganic ceramic SE, the ionic transport path crosses a ceramic-polymer phase boundary, which leads to additional polarization through charge transfer and ohmic resistance. State-of-the-art literature discusses the influence of ceramic particles in polymer electrolytes, but falls short on the impact of ceramic-polymer phase boundaries on the total cell performance of ASSBs [6, 7, 8]. To allow for the simulation of hybrid full cells, a pseudo-two-dimensional (p2D) physicochemical model is introduced within this work. The model is based on the Newman approach, modified with a description for the ceramic-polymer phase boundary [9]. In equilibrium state, the potential drop across the ceramic-polymer boundary was modeled with the Donnan-potential condition as recently proposed by Kim et al. [10]. Under current flow, additional polarization occurs at the interface due to electrochemical charge transfer, which was modeled by the Butler-Volmer equation, and ohmic contact resistance. The conservation of mass and charge over the phase boundary was secured with a current, flux, and a potential boundary condition. A model cell was defined (see figure 1) and parametrized using material-specific values for the ionic and electronic transport characteristics as well as the interface and charge transfer properties. Since the focus of this study was on the ceramic-polymer phase boundary, ideal plating and stripping behavior at the Li-metal anode were assumed neglecting irregular lithium deposition, e.g., lithium dendrite formation. As separator material, the well-known ceramic LLZO SE was modeled. A composite cathode with NMC-622 as CAM and PEO/LiTFSI as polymer electrolyte was assumed. The lower part of figure 1 shows the reduced 1D-model geometry and the ion transport mechanisms in each model domain. The established physicochemical model was applied to identify performance-limiting effects in hybrid ASSBs to conclude on cell designs achieving high energy and power densities. To quantify and localize the polarization contributions in each domain, arising from SE ionic conductivity, diffusion or charge-transfer processes, as well as phase boundaries, the method proposed by Nyman et al. was used [11]. Figure 2 a) shows the results of polarization analysis when simulating a 0.1C charge, while figure 2 b) depicts the results for a 1C charge. Diffusion limitation in the polymer electrolyte led to high concentration gradients in the polymer-phase of the composite cathode, resulting in high diffusion polarization at elevated charging rates as shown in figure 2 b). This determined a critical current density at cell level, which was caused by large Li-ion concentration gradients and a possible depletion of Li-ions near the ceramic separator. The overall cell polarization was further enhanced by the ceramic-polymer phase boundary. For the contact case of LLZO versus PEO/LiTFSI considered here, the equilibrium potential between the phases was calculated according to the theory of Donnan to 31 mV. Since a wide range of values for the contact resistance at the ceramic-polymer interface is reported in the literature [6, 7], ohmic polarization could be important and was therefore evaluated as a function of different contact resistances. A critical contact resistance was determined to achieve the requirements for future battery technologies regarding energy and power density. Figure 1

In solid-state lithium-ion batteries (SSLIBs), the fraction of active materials involved in electrode electrochemistry reduces with the increase of electrode thickness. Conventional wisdom suggests that the degree of reaction linearly decreases toward the current-collector as that in the lithium-ion batteries, which is, however, limited by the high difficulty of experimental capture of operando transport of charge & mass. Electrode dynamics simulations can provide space visualization but are usually based on assumed or simplified models. Herein, we build digital-twin electrodes with digital-space voxel microstructure based on synchrotron tomography, which transforms the electrode architecture from real space to digital space for the construction of precision models. From the digital-model-driven simulation, we find an interesting "lithium trapping" effect, stemming from susceptible lithium stuck in the solid electrolyte, triggers an inadequate reaction of the intermediate region of electrodes but not near current-collector region. Then, we construct locally accelerated ion paths activating the lithium trapping, indicating that this strategy can significantly guide the sustainable battery design for next-generation energy storage.

Understanding and controlling the atomistic-level reactions governing the formation of the solid-electrolyte interphase (SEI) is crucial for the viability of next-generation solid state batteries. However, challenges persist due to difficulties in experimentally characterizing buried interfaces and limits in simulation speed and accuracy. We conduct large-scale explicit reactive simulations with quantum accuracy for a symmetric battery cell, {\symcell}, enabled by active learning and deep equivariant neural network interatomic potentials. To automatically characterize the coupled reactions and interdiffusion at the interface, we formulate and use unsupervised classification techniques based on clustering in the space of local atomic environments. Our analysis reveals the formation of a previously unreported crystalline disordered phase, Li$_2$S$_{0.72}$P$_{0.14}$Cl$_{0.14}$, in the SEI, that evaded previous predictions based purely on thermodynamics, underscoring the importance of explicit modeling of full reaction and transport kinetics. Our simulations agree with and explain experimental observations of the SEI formations and elucidate the Li creep mechanisms, critical to dendrite initiation, characterized by significant Li motion along the interface. Our approach is to crease a digital twin from first principles, without adjustable parameters fitted to experiment. As such, it offers capabilities to gain insights into atomistic dynamics governing complex heterogeneous processes in solid-state synthesis and electrochemistry.

The kinetics of composite cathodes for solid-state batteries (SSBs) relies heavily on their micro-structure. Spatial distribution of the different phases, porosity, interface areas, and tortuosity factors are important descriptors that need accurate quantification for models to predict the elec-trochemistry and mechanics of SSBs. In this study, high-resolution focused ion beam-scanning electron microscopy tomography was used to investigate the microstructure of cathodes com-posed of a nickel-rich cathode active material (NCM) and a thiophosphate-based inorganic solid electrolyte (ISE). The influence of the ISE particle size on the microstructure of the cathode was visualized by 3D reconstruction and charge transport simulation. By comparison of experimen-tally determined and simulated conductivities of composite cathodes with different ISE particle sizes, the electrode charge transport kinetics is evaluated. Porosity is shown to have a major influence on the cell kinetics and the evaluation of the active mass of electrochemically active particles reveals a higher fraction of connected NCM particles in electrode composites utilizing smaller ISE particles. The results highlight the importance of homogeneous and optimized mi-crostructures for high performance SSBs, securing fast ion and electron transport.

No abstract available

Electro-chemo-mechanical expansion at metal/electrolyte interfaces is a rate limiting factor in solid-state lithium (SSLiBs) and sodium (SSNaBs) batteries. In this presentation we will explain the roles of composition, structure, and interfaces in achieving extremely high current densities for SSNaBs and SSLiBs of 30 mA/cm2 and 100 mA/cm2, respectively, without dendrites at room temperature and no applied pressure.

The high interface resistance at the cathode-sulfide electrolyte interface is still a crucial drawback in an all-solid-state battery, unlike the initial expectation that the all-solid-state interface would enhance electrochemical stability by reducing side reactions at the interface. In this study, we examined the fundamental mechanism of unexpected reactions at the interface of LiNi0.8Co0.1Mn0.1O2 (NCM811) and argyrodite (Li6PS5Br0.5Cl0.5, LPSBC) sulfide solid electrolytes based on the combined method of multiscale simulations and electrochemical experiments. The high interface resistance originates from the formation of a passivating layer at the interface combined with irregular atomic and electronic structures, Li depletion, mutual element exchange, and mechanical contact loss between the oxide cathode and sulfide solid electrolyte. We also confirmed that these side reactions were suppressed by O substitutions to sulfide solid electrolyte (LPSOBC), and then the chemo-mechanical stability of the all-solid battery was enhanced by alleviating the side reactions at the interface. This study provides rational insights into the design of an interface for all-solid-state batteries.

All-Solid-State Batteries (ASSBs) are increasingly perceived as a viable substitute to Li-ion batteries, primarily due to their enhanced safety and energy density. ASSBs utilize a non-flammable solid electrolyte, significantly reducing the risk of fire hazards. Furthermore, they can operate under a broader temperature and voltage spectrum. This research aims to optimize the composition of anode electrode materials, comprised of a particle mixture of Active Material (AM), Solid Electrolyte (SE), and conductive additive. Graphite, a frequently used AM, is favored for its low voltage characteristics and its low volume expansion during charge cycling. Additionally, graphite's low Young Modulus is beneficial in preventing the build-up of substantial stresses within the battery cell. Silicon (Si) is another appealing material due to its high gravimetric capacity, which is up to ten times greater than that of graphite. However, during Li insertion, the crystalline structure transitions to an amorphous state, resulting in a substantial expansion of up to 300%, which triggers a significant accumulation of stress. Numerous strategies have been explored to alleviate the stress build-up resulting from expansion by adding graphite or carbon nanotubes (CNTs). The latter provides void spaces which can accommodate the volumetric expansion. Furthermore, the CNTs possess the capacity to retain the electrode's structure during volume expansion, which is advantageous for maintaining structural integrity, preserving solid-solid contacts, and enhancing the electrical conduction network. Owing to these factors, ASSBs with the addition of CNTs have demonstrated improved cycling performance. 1 Simulating Si composite solid-state anodes presents a significant challenge due to the stress induced by localized Si particles. The substantial expansion of Si can lead to the formation of shell voids in minute localized regions surrounding the microscopic Si particles. This complexity makes it difficult to simulate the dynamics using traditional finite element (FE) based mechanical models. An alternative solution is to employ the Discrete Element Method (DEM) which is a type of particle-based models that solve for Newton's laws of motion for each particle. While continuum models are instrumental in deterministically calculating the properties of bulk materials, DEMs can be utilized to compute particle slippage and the evolution of void regions between individual particles, which influence the local contact area of solid-solid interactions. In our previous research,2 we developed a multiscale chemo-mechanical DEM model for Si anode solid-state batteries. This model encompasses two stages: fabrication and cell operation. During the fabrication stage, particles were simulated within a high-pressure mold, for which we devised an elasto-plastic contact model. Throughout the cell operation stage, we simulated Li insertion and AM volume expansion. However, in current study it was observed that during charge cycling in confined cell volume, the pressure exceeded levels that are acceptable for practical applications. Furthermore, during discharge, the contact areas between particles declined and AM progressively lost its ability to form an electronic percolative chain, reducing the discharge capacity. We successfully incorporated CNTs into the DEM model by linking particles into elongated fibers, each with robust adhesive fusion bonds. The electronic percolation network and interface contact areas saw significant improvement with the addition of CNTs. By further implementing this model, we can determine the optimal composition of Si, graphite and CNTs based on several performance indicators, including the electrode's power density and capacity fade. The study will be broadened to simulate various geometrical configurations, such as a particle mixture of Si and graphite, and coated Si and SE particles on CNT structures. Acknowledgements We gratefully acknowledge the support of the Japan Science and Technology Agency (JST) through the JST-Mirai Program, Grant number JPMJMI24G1. References L. Hu, X. Yan, Z. Fu, J. Zhang, Y. Xia, W. Zhang, Y. Gan, X. He, and H. Huang, ACS Appl. Energy Mater., 5, 14353–14360 (2022). M. So, S. Yano, A. Permatasari, T. D. Pham, K. Park,. and G. Inoue, Journal of Power Sources, 546, 231956 (2022).

As solid‐state batteries (SSBs) emerge as leading contenders for next‐generation energy storage, chemo‐mechanical challenges and instabilities at solid‐solid interfaces remain a critical bottleneck. Ensuring sufficient interfacial contact within composite cathode architectures often requires the application of high stack pressures, posing a significant hurdle in the development of viable, large‐scale SSBs. In this work, the impact of stack pressure is investigated on the performance of solid‐state composite cathodes comprised of single‐crystal LiNi0.5Mn0.3Co0.2O2 (SC‐NMC532) active material particles and a Li6PS5Cl (LPSCl) solid electrolyte phase. By unraveling the complex interplay between stack pressure and microstructure‐dependent mechanisms, the profound influence on interfacial resistances, cathode utilization dynamics, current constriction effects, and lithiation heterogeneities are revealed. Through a comprehensive examination of coupled reaction kinetics and transport interactions at the electrode and particle length scales, the implications of stack pressure at different C‐rates and microstructural arrangements are elucidated, thereby delineating the limiting mechanisms that are prevalent at low stack pressures. This work underscores the critical role of optimizing the cathode microstructure to mitigate the chemo‐mechanical challenges associated with SSB operation at low stack pressures, offering valuable insights and design guidelines for the development of high‐performance SSBs.

We present a mechanistic theory for predicting void evolution in the Li metal electrode during the charge and discharge of all-solid-state battery cells. A phase field formulation is developed to model vacancy annihilation and nucleation, and to enable the tracking of the void-Li metal interface. This is coupled with a viscoplastic description of Li deformation, to capture creep effects, and a mass transfer formulation accounting for substitutional (bulk and surface) Li diffusion and current-driven flux. Moreover, we incorporate the interaction between the electrode and the solid electrolyte, resolving the coupled electro-chemical-mechanical problem in both domains. This enables predicting the electrolyte current distribution and thus the emergence of local current 'hot spots', which act as precursors for dendrite formation and cell death. The theoretical framework is numerically implemented, and single and multiple void case studies are carried out to predict the evolution of voids and current hot spots as a function of the applied pressure, material properties and charge (magnitude and cycle history). For both plating and stripping, insight is gained into the interplay between bulk diffusion, Li dissolution and deposition, creep, and the nucleation and annihilation of vacancies. The model is shown to capture the main experimental observations, including not only key features of electrolyte current and void morphology but also the sensitivity to the applied current, the role of pressure in increasing the electrode-electrolyte contact area, and the dominance of creep over vacancy diffusion.

No abstract available

Solid-state Li-ion batteries, based on Ni-rich oxide cathodes and Li-metal anodes, can theoretically reach a high specific energy of 393 Wh kg−1 and hold promise for electrochemical storage. However, Li intercalation-induced dimensional changes can lead to crystal defect formation in these cathodes, and contact mechanics problems between cathode and solid electrolyte. Understanding the interplay between cathode microstructure, operating conditions, micromechanics of battery materials, and capacity decay remains a challenge. Here, we present a microstructure-sensitive chemo-mechanical model to study the impact of grain-level chemo-mechanics on the degradation of composite cathodes. We reveal that crystalline anisotropy, state-of-charge-dependent Li diffusion rates, and lattice dimension changes drive dislocation formation in cathodes and contact loss at the cathode/electrolyte interface. These dislocations induce large lattice strain and trigger oxygen loss and structural degradation preferentially near the surface area of cathode particles. Moreover, contact loss is caused by the micromechanics resulting from the crystalline anisotropy of cathodes and the mechanical properties of solid electrolytes, not just operating conditions. These findings highlight the significance of grain-level cathode microstructures in causing cracking, formation of crystal defects, and chemo-mechanical degradation of solid-state batteries. The performance of solid-state batteries is affected by stress responses of their complex microstructure to volume changes from Li+ intercalation. Here, authors present a chemo-mechanical model to study the impact of grain-level chemo-mechanics on the degradation of composite positive electrodes.

In all-solid-state batteries (ASSBs), (electro)chemo-mechanical aspects such as uneven interfaces, cathode-electrolyte interphase formation, delamination, fracture, defects, etc., are the major factors in capacity fade but remain largely unknown. Nonhomogeneous transfer of lithium ions can cause significant variations in strain and stress within battery electrodes, leading to degradation in battery performance. In all-solid-state batteries (ASSBs), the lithium pathway and the associated strain/stress field become more intricate due to the (electro)chemo-mechanical reaction at the electrode-electrolyte interfaces. The dynamic volume change in active particles are heavily influencing by strength of the solid electrolyte and interfacial conformality. This can continually alter the lithium pathway and the internal stress field, leading to recurrent redefinitions of (electro)chemo-mechanical environment. Here, we have developed an operando coherent X-ray imaging platform and associated analysis methodologies. This technology can track the nanoscale transport of lithium and the strain evolution of individual electrode particles in ASSBs. With this platform, we gained a comprehensive electrochemical and mechanical understanding of the cycling properties of single electrode particles in ASSBs.

Void growth during the plating and stripping process is an important interfacial phenomenon that hinders the development of Li-metal solid-state batteries (SSBs) because it can potentially result in inter-component delamination or growth of Li dendrites. Behind the void growth is the complex interaction between electrochemistry and mechanics. Voids usually grow from micro- or nanoscale initial imperfections on the Li-solid electrolyte (SE) interface. It is, therefore, important to analyze the stress concentration at the initial void tips, which largely determines the growth/shrinking of the void as well as the consequent changes in the internal resistance and overall battery efficiency. Recently, the development of in situ operando experimental technology has enabled the electro-chemo-mechanical characterization of the void growth phenomenon on the Li-SE interface. In this study, we explore how voids in SSBs evolve with a multi-physics model in COMSOL Multiphysics. Based on this model, we perform a systematic parametric study in the space of the mechanical stack pressure and the applied current density. The simulation results show different deformation patterns and potential failure mechanisms under different combination of stack pressure and current density. To better understand the phenomena, we develop an analytical solution to understand the void deformation induced by the inhomogeneous Li-ion concentration field under stack pressure. This analytical approach offers a complementary and intuitive perspective on the mechanical aspect of our simulation findings. By combining the simulation and analytical solutions, we depict a phase diagram, in which we identify the “safe zone” that will not result in void growth. The new insights of this research hold the promise of guiding the development of stabilized SSB interfaces.

Solid-state batteries offer the promise of improved energy density and safety compared to lithium-ion batteries. Here, I will present our emerging understanding of the key differences between how high-capacity anode materials behave in solid-state batteries compared to in conventional liquid-electrolyte batteries. The electro-chemo-mechanical evolution of materials at solid-solid electrochemical interfaces is different than at solid/liquid interfaces, and contact evolution in particular plays a critical role in determining the behavior of solid-state batteries. I will focus on mechanisms governing lithium metal anodes (including lithium in the “anode-free” configuration) and alloy anodes. Lithium metal anodes in solid-state batteries are intrinsically limited by void formation during stripping and dendrite growth during plating. Anode-free solid-state batteries, in which there is no initial lithium metal at the anode interface, offer extremely high energy density, but there is a lack of understanding of how their behavior differs from excess-lithium electrodes. Using X-ray tomography, cryo-FIB, and finite-element modeling, we show that anode-free solid-state batteries are intrinsically limited by current concentrations at the end of stripping due to localized lithium depletion. This causes accelerated short circuiting compared to lithium-excess cells. Based on these results, the beneficial influence of metal alloy interfacial layers on controlling lithium evolution and mitigating contact loss from localized lithium depletion, including at low stack pressures, will be discussed. X-ray tomography is further shown to be particularly useful in observing the dynamic evolution of lithium metal, including void formation and filament growth. The second part of the talk focuses on alloy anodes. Alloy anodes typically exhibit fast capacity decay in lithium-ion batteries because of excessive solid-electrolyte interphase growth. We show that alloy anodes in solid-state batteries can exhibit improved interfacial stability and enhanced cyclability. Furthermore, in situ measurement of stack pressure evolution during cycling shows that the volume changes of alloy anodes can lead to large pressure swings within the cell, giving insight into electrode composite evolution. Based on these insights, we present a new design for dense foil alloy anodes. This design offers a paradigm that does away with slurry coating, potentially reducing manufacturing costs. Taken together, these findings show the importance of controlling chemo-mechanics and interfaces in solid-state batteries for improved energy storage capabilities.

As a promising future energy storage solution, all-solid-state battery (ASSB) technologies with less flammable and non-volatile solid electrolytes (SEs) have attracted great attention in recent decades for their potential to achieve higher energy densities and improved safety compared to conventional Li-ion batteries. Nevertheless, challenges remain for practical deployment due to electro-chemo-mechanical instabilities at solid-solid interfaces. These interfaces, which include homogeneous/internal interfaces such as grain boundaries (GBs) and heterogeneous/external interfaces between SE and electrode materials, can impede Li-ion transport, reduce electrochemically active sites, deteriorate performance, and eventually lead to cell failure. To resolve these issues, fundamental understanding of the structure-property relationships at the interfaces, which govern the electrochemical performance of ASSBs, is required. In this talk, we will present our recent results utilizing large-scale molecular dynamics simulations with validated machine-learning force fields to explore interfacial degradations in ASSBs directly in atomic scale and reveal the fundamental mechanisms of physicochemical phenomena observed in experiments. First, we surveyed different geometries and compositions at the garnet Li 7 La 3 Zr 2 O 12 (LLZO) SE/LiCoO 2 (LCO) cathode interfaces simulating co-sintering environment at high temperatures, which suggest the propensities of chemical degradation depending on the interfacial chemistry as well as the mechanisms for the formation of Co-rich phases at LLZO GBs. We also explored the mechanisms of dopant segregation in Al/Ta-doped LLZO and elucidate their effects on the properties of materials and implications to the battery performance. At last, we will address the micro-crack propagation behavior and mechanical responses in LLZO. In summary, our results reveal how atomic details of the dynamically evolving interfaces dictate the performance of ASSBs and provide guidance for processing and interface design to achieve desired performance. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract number DEAC52-07NA27344. Authors acknowledge funding support from the Vehicle Technologies Office, Office of Energy Efficiency and Renewable Energy, U.S. Department of Energy and computational resource support from the Innovative and Novel Computational Impact on Theory and Experiment (INCITE) program. This research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357. Additional computational resources were sponsored by the Department of Energy's Office of Energy Efficiency and Renewable Energy located at the National Renewable Energy Laboratory and the Computing Grand Challenge program from Lawrence Livermore National Laboratory.

Electric vertical take-off and landing (eVTOL) aircraft have garnered extensive attention due to their potential to enable fast, efficient, and clean urban transportation. However, their stringent and dynamic mission profiles require a resilient and energy-dense battery system. While solid-state batteries (SSBs) due to their higher specific energy and enhanced safety present a promising opportunity for these systems, they face several key challenges including void formation at the Li-metal interface and accelerated cell polarization under high discharge current densities. The chemo-mechanical response and interface stability of solid-state batteries under such dynamic discharge scenarios is still unknown. In this presentation, we investigate the void formation, growth, and relaxation mechanism at the Li/solid-electrolyte interface under power profiles corresponding to different eVTOL missions. The critical dependence of the contact loss and polarization behavior on the external pressure and temperature is delineated. The impact of the duration of different mission phases (e.g., takeoff, landing) on the onset and severity of void formation is evaluated. Our work analyzes the impact of electrode/cell design parameters on the tradeoff between achievable energy and power densities, offering mechanistic insights into the development of next-generation SSBs for eVTOL aircraft.

Anode-free, all-solid-state alkali metal batteries provide a promising avenue for the realization of safe, high energy density battery technologies. Among the various types of solid electrolytes, solid polymer electrolytes (SPEs), particularly crosslinked networks, have demonstrated the best long-term cycling stability due to their ability to conform uniformly to the electrode surface and accommodate the significant volume changes during charging and discharging. Although SPEs have shown significant potential for stabilizing alkali metal deposition, dendrite formation, which can lead to short-circuiting and poor reversibility, still remains a major hurdle. Despite significant progress in the development of SPEs for alkali metal batteries, the coupled chemo-mechanical phenomena governing in situ anode formation and the mechanistic origins of poor reversibility remain poorly understood. To better understand how to regulate these instabilities, we designed a series of solid polymer electrolytes with precisely controlled mechanical properties and interfacial chemistry, allowing us to investigate how these properties and their spatial distribution affect sodium metal morphology during plating and stripping. We reveal the effect of interfacial chemistry, roughness, and compliance on the nucleation and growth of sodium metal at the SPE/metal interface. While interfacial chemistry and roughness are shown to govern nucleation, sodium metal growth and its reversibility upon stripping are primarily dictated by the mechanical properties of the SPE. Overall, the work presented here will provide a comprehensive picture of the role of SPE chemistry and mechanical properties on sodium metal deposition and stripping, offering valuable guidance for the design of next-generation SPEs.

Recent advancements in solid electrolyte research have revived interest in the concept of silicon anodes for All-Solid-State Batteries (aSSBs). Tan et al. have recently proposed stable cyclic performance of micro-grain size pure silicon anodes paired with sulfide-based solid electrolytes [1]. This development has opened pathways toward potential aSSBs without encountering dendrite growth issues. This rediscovery of the thin-film a-silicon anodes concept has sparked computational interest in simulating the fracture-chemo-mechanical silicon lithiation mechanism. Understanding chemical reactions during lithiation and crack evolution during de-lithiation processes are intriguing topics. Especially, elastic-plastic deformation coupled with phase-field continuous fracture is crucial in comprehending the underlying physics and enhancing performance of battery cell through reverse engineering approaches. In this work, we develop a thermodynamically consistent deformation-diffusion-damage coupled framework to model the evolution of dense, thin-film-like a-silicon anodes during lithiation and delithiation. During delithiation, tensile stress develops inside the film as the lithiated film overcomes the initial stack pressure and compressive stress prevalent during lithiation. As tensile stress and strain evolve, randomly distributed weak spots lead to crack nucleation. This fracture occurs throughout the silicon film, forming sharp vertical cracks, and depending on surface conditions along the solid-state electrolyte, some interfacial cracks may emerge, leading to permanent contact loss and resulting in capacity reduction. From the model, we observed “mud crack” like phenomena, where crack distribution is not controlled by particle’s property, but entire cluster’s thickness matters. While flat model suggests that one that nucleate the crack was weak spots where they make stress concentration over entire body, whether they can evolve into big vertical crack mostly governed by connectivity of such weak spot maps. However, from our interface roughness model, what governs the crack evolution most was not the randomly distributed weak spot, but its geometric relative thickness difference between one another. Due to manufacturing process, perfect interface is hard to be achieved and such geometric irregularity always exist, thus, additive and binder studies along the silicon anode and its interface between sse would be key to achieve long and stable life span for a-silicon based aSSBs. Reference [1] Tan, Darren HS, et al. "Carbon-free high-loading silicon anodes enabled by sulfide solid electrolytes." Science 373.6562 (2021): 1494-1499.

All solid-state battery technologies show great promises as next-generation energy storage solutions with opportunities to achieve higher energy density and improved safety features compared to the current liquid-based lithium-ion battery technologies. However, their practicality is limited by high interfacial impedance for ion transport and poor mechanical stability during cycles. In this talk, I will address the key chemo-mechanical coupling effect that critically defines the functionality of interfaces in all solid-state lithium batteries. I will consider the interface of garnet Li7La3Zr2O12 solid-electrolyte and LiCoO2 cathode as an example to demonstrate the powerfulness of multiscale modeling to identify degradation modes that can attribute to high interfacial resistance for Li-ion transport and mechanical failure. Mitigation strategies will be discussed based on manipulation of processing condition and the resulting microstructures to improve interfacial stability and thus enhance the cycling performance of catholyte. This work was sponsored by the Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office and was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Structural heterogeneity within solid-state electrodes can have a significant impact on material utilization and reaction rates. This reaction heterogeneity is greater in solid state systems in comparison to conventional liquid electrolytes because it requires exquisite solid-solid contact between the active energy storage materials and the solid ion conducting phase (e.g. solid electrolyte) [1]. Electrode reaction behaviors encompass electrochemical lithiation and delithiation dynamics and chemo-mechanical processes such as volume change and fracture [2]. Understanding the connection between structural heterogeneity and reaction behavior is crucial for understanding degradation mechanisms and optimizing solid state battery architectures. Herein, we examine the implications of reaction heterogeneity in an additive-free, crystallographically textured electroplated lithium cobalt oxide (LCO) cathode [3]. The electroplated dense cathode alleviates the need for any solid electrolyte material in the cathode. A diverse set of synchrotron-based operando and ex situ experiments are combined with modeling to uncover the relationship between structural heterogeneity and reaction behavior. Operando energy dispersive X-ray diffraction and ex situ 3D XANES are used to identify reaction heterogeneity and X-ray nanotomography is used to probe nano-scale structural heterogeneity. Nanoindentation is utilized to determine the mechanical properties of LCO. To validate the results, we combine these experimental results with transport and mechanics modeling. Through this comprehensive characterization approach, we confirm that the reaction behavior of cathode in our model is mainly determined by the morphological heterogeneity rather than the Li diffusion within the electrode. Structural heterogeneity causes localized high stress and leads to fracture, which in turn limit the full utilization of the cathode. Reference [1] Jung, S.H., Kim, U.H., Kim, J.H., Jun, S., Yoon, C.S., Jung, Y.S. and Sun, Y.K., 2020. Ni‐rich layered cathode materials with electrochemo‐mechanically compliant microstructures for all‐solid‐state Li batteries. Advanced Energy Materials, 10(6), p.1903360. [2] Liu, X., Zheng, B., Zhao, J., Zhao, W., Liang, Z., Su, Y., Xie, C., Zhou, K., Xiang, Y., Zhu, J. and Wang, H., 2021. Electrochemo‐mechanical effects on structural integrity of Ni‐rich cathodes with different microstructures in all solid‐state batteries. Advanced Energy Materials, 11(8), p.2003583. [3] Zahiri, B., Patra, A., Kiggins, C., Yong, A.X.B., Ertekin, E., Cook, J.B. and Braun, P.V., 2021. Revealing the role of the cathode–electrolyte interface on solid-state batteries. Nature Materials, 20(10), pp.1392-1400. Figure 1

Solid-state batteries (SSBs) are promising alternatives to the incumbent lithium-ion technology; however, they face a unique set of challenges that must be overcome to enable their widespread adoption. These challenges include solid–solid interfaces that are highly resistive, with slow kinetics, and a tendency to form interfacial voids causing diminished cycle life due to fracture and delamination. This modeling study probes the evolution of stresses at the solid electrolyte (SE) solid–solid interfaces, by linking the chemical and mechanical material properties to their electrochemical response, which can be used as a guide to optimize the design and manufacture of silicon (Si) based SSBs. A thin-film solid-state battery consisting of an amorphous Si negative electrode (NE) is studied, which exerts compressive stress on the SE, caused by the lithiation-induced expansion of the Si. By using a 2D chemo–mechanical model, continuum scale simulations are used to probe the effect of applied pressure and C-rate on the stress–strain response of the cell and their impacts on the overall cell capacity. A complex concentration gradient is generated within the Si electrode due to slow diffusion of Li through Si, which leads to localized strains. To reduce the interfacial stress and strain at 100% SOC, operation at moderate C-rates with low applied pressure is desirable. Alternatively, the mechanical properties of the SE could be tailored to optimize cell performance. To reduce Si stress, a SE with a moderate Young’s modulus similar to that of lithium phosphorous oxynitride (∼77 GPa) with a low yield strength comparable to sulfides (∼0.67 GPa) should be selected. However, if the reduction in SE stress is of greater concern, then a compliant Young’s modulus (∼29 GPa) with a moderate yield strength (1–3 GPa) should be targeted. This study emphasizes the need for SE material selection and the consideration of other cell components in order to optimize the performance of thin film solid-state batteries.

Solid-state batteries (SSBs) could replace conventional lithium-ion batteries due to the possibility of increasing the energy density of the cells by using lithium metal as the anode material.[1] Among the many electrolyte candidates for lithium SSBs, the lithium thiophosphates are particularly interesting due to their high ionic conductivities at room temperature (>1 mS/cm). However, the (electro)chemical stability of these solid electrolytes is limited and not fully compatible with state-of-the-art high-potential cathode active materials[2] or the lithium metal anode.[3] At the cell level, the formation of interparticle voids between the various battery components (solid electrolyte, cathode active material, anode material, additives, decomposition interphases) hinder the net transport during cycling. To address the latter electro-chemo-mechanical challenges, we are exploring hybrid material approaches, in which we combine established materials (solid electrolytes, liquid electrolytes and/or polymer additives) with state-of-the-art cathode active materials and test their electrochemical performance in solid-state battery (half-)cells. Such cycling results are complimented by detailed electrochemical transport studies in symmetrical cells using DC polarization and electrochemical impedance spectroscopy, including transmission-line modeling. ex.situ chemically-specific spectroscopic methods are used to support our hypotheses and interpretation of the electrochemical results. Taken together, we attain a better picture on the positive (or negative) role hybrid materials play in SSBs. In this talk, we will showcase two hybrid systems, namely ionic liquid/thiophosphate lithium hybrid electrolytes and conductive polymers additives in NMC-based catholyte composites for Li6PS5Cl cells. The first part of the talk we will discuss the results in which we evaluate the performance of liquid electrolyte-solid electrolyte materials against lithium metal using galvanostatic electrochemical impedance spectroscopy. In the second part, we elucidate the partial ionic and electronic transport in polymer electrolyte-Li6PS5Cl-NMC catholytes as a function of polymer content using impedance spectroscopy and its effect in the cycling performance, both the stability as well as the magnitude of the discharge capacities. These systems serve as a good starting point for the further development and incorporation of hybrid materials in SSBs. Literature: [1] W. G. Zeier and J. Janek Nature Energy, 2016, 1, 16141. [2] G.F. Dewald, S. Ohno, M.A. Kraft, R. Kroever, P. Till, N.M. Vargas-Barbosa, J. Janek, W.G. Zeier Chem. Mater. 2019, 31, 8328. [3] L. M. Riegger, R. Schlem, J. Sann, W. G. Zeier, J. Janek, Angew. Chem. Int Ed 2021, 60, 6718. Figure 1

Rapid electric vehicle adoption has elevated battery safety and high energy density from desirable attributes to core requirements, bringing all-solid-state batteries (ASSBs) employing sulfide solid electrolytes (SEs) to the forefront as credible next-generation candidates. Yet, in practice, the composite cathode remains the principal bottleneck. In Ni-rich high-capacity cathode active materials (CAMs) paired with sulfide SEs, parasitic interfacial reactions and contact degradation during charge–discharge are recognized sources of performance loss. In addition, the spatial distribution and percolation characteristics of CAM and SE complicate the ionic and electronic pathways, hindering uniform electrochemical reactions throughout the electrode. These issues are exacerbated in thick electrodes, where ionic transport resistance, electronic transport resistance, and contact resistance—collectively termed “electrode resistance”—become markedly larger than in conventional lithium-ion batteries. In impedance measurements, the electrode resistance contribution rarely manifests as an isolated feature; instead, it overlaps with signals arising from interfacial processes, including charge-transfer resistance (R ct ) and film resistance (R film ), thereby complicating mechanistic interpretation. The thicker the electrode, the stronger this overlap becomes, and the more uncertain the assignment of spectral features to purely interfacial or purely transport origins. Despite this reality, prior studies have largely emphasized half-cell-based impedance analyses focused on interfacial reaction resistances. Under conditions where electrode resistance and interfacial resistance coexist and co-evolve, such a narrow focus limits the reliability of impedance interpretation and can lead to ambiguous or even misleading conclusions. To enable trustworthy assessment of interfacial behavior in ASSBs and to guide high-energy designs, it is therefore essential to systematically separate and quantify electrode resistance components from genuine interfacial contributions, and to clarify their relative weights under practically relevant electrode conditions. In this study, we investigate the impedance of composite ASSB cathodes with the goal of improving the reliability of interpretation by explicitly decoupling electrode and interface contributions. Using electrochemical impedance spectroscopy (EIS) coupled with Distribution of Relaxation Times (DRT) analysis on composite-cathode half cells, we examine how the impedance response varies with state of charge (SoC) and areal loading—the latter determining electrode thickness. By scanning SoC and areal loading in a systematic manner, we construct a frequency-resolved picture in which processes can be separated by their SoC sensitivity and their evolution with thickness. This approach enables identification of distinct features associated with electrode resistance, charge transfer at the CAM/SE interface, and the formation of interfacial films that arise during cycling. Across SoC and areal-loading conditions, three dominant DRT peaks emerge, labeled P1, P2, and P3. P1 remains essentially invariant with SoC and occupies the high-frequency region of the spectrum, indicating an origin in electrode resistance that reflects through-plane ionic/electronic pathways and contacts within the composite network. P2 exhibits a U-shaped dependence on SoC, with larger values at Li-poor and Li-rich extremes and a minimum at intermediate states, a hallmark of R ct governed by composition-dependent kinetics at the CAM/SE interface. P3 gradually stabilizes as cycling proceeds, consistent with the growth and subsequent stabilization of a cathode–electrolyte interphase (CEI) that contributes a film-resistance component. The concurrent presence of these features explains why interfacial analysis alone can be unreliable in thick electrodes: as electrode resistance rises, its high-frequency signature can extend into the mid-frequency range and partially obscure or distort interfacial signals. Areal-loading-dependent measurements further reveal a critical loading that separates two regimes of behavior. Below this threshold, increasing electrode thickness leads to a pronounced growth in P1, reflecting the amplification of electrode resistance with extended transport pathways. In the same regime, P2 and P3 decrease with increasing areal loading, a trend attributed to the effective increase in electrochemically active area and improvements in local CAM–SE contact as the composite volume increases. Above the critical loading, however, spectral separation deteriorates: signals associated with electrode resistance and R ct begin to overlap. Taken together, these results quantitatively map how electrode and interfacial resistances contribute to the overall impedance as a function of areal loading and SoC. They show that electrode resistance can significantly bias the mid- and low-frequency response and thereby distort conclusions about interfacial reactions if it is not first isolated and properly accounted for in the analysis. On this basis, we advocate an analysis sequence in which high-frequency features associated with electrode resistance are identified and considered before interpreting the mid- and low-frequency regime associated with R ct and CEI-related film resistance. The study strengthens the foundation for accurate interfacial analysis in thick ASSB electrodes and supports rational strategies for energy-density enhancement and performance optimization.

All-solid-state batteries (ASSBs) are being actively researched worldwide as promising next-generation alternatives to lithium-ion batteries (LIBs). To further enhance the performance of ASSBs, it is essential to quantitatively understand the contact interface between the active material and the solid electrolyte (SE) in the electrode. However, there is no established method to quantitatively evaluate this contact interface. In this study, we assessed the contact interface between the active material and the SE-which is challenging to quantify under constrained test fixture conditions-using electrochemical impedance spectroscopy (EIS). The capacitance obtained from EIS measurements served as a quantifiable indicator. We demonstrated that approximation methods enable accurate capacitance quantification under practical EIS measurement conditions (up to approximately 10 mHz) for battery development. An electrode composite, prepared using a cathode active material and a sulfide-based SE, exhibited increased capacitance with longer mixing times, confirming an improved contact interface between the active material and the SE. Capacitance was highlighted as a critical parameter, exhibiting a correlation with the forming and stacked pressures in ASSBs, and was strongly linked to cell performance. To the best of our knowledge, this study is the first to quantify the contact interface between the active material and the SE in solid-state batteries using capacitance as an indicator.

Solid‐state lithium metal batteries (SSLMBs) hold promise for next‐generation energy storage but suffer from interfacial instabilities that limit performance and lifespan. A critical challenge remains: understanding how engineered interphases affect ion transport and battery behavior across scales. Here, a multiscale modeling framework that quantitatively links microscale lithium‐ion concentration gradients at functional interphases with full‐cell electrochemical performance is presented. Using coupled FiPy‐based diffusion simulations and PyBaMM‐based cell modeling, a Li–LiAl–LiF interfacial layer with a gradual change in composition—known as a gradient interphase is analyzed, and it is shown that its parabolic concentration profile—arising from steady‐state diffusion—directly governs voltage stability, impedance spectra, and power delivery. The framework reproduces key experimental signatures such as Warburg impedance and voltage flattening, while outperforming conventional models in predicting performance stability. This is the first integrated simulation tool to connect interfacial morphology to system‐level metrics in SSLMBs, offering a predictive path toward the design of stable, high‐efficiency interfaces for solid‐state energy storage.

Anode‐free manufacturing of solid‐state batteries (SSBs) shows promise to maximize energy density by eliminating excess lithium (Li) and simplifying battery production. However, high reversibility during discharge (stripping of Li) is necessary for long‐lifetime SSBs with a limited Li reservoir. Further, the plastic flow of Li changes depending on the Li thickness, leading to possible differences in discharge performance under stack pressure. This work investigates the pressure‐dependent discharge performance of anode‐free manufactured SSBs with in situ plated Li and compares the performance to that of conventional thick Li foil cells. Distinct stripping behavior is observed at low pressures (0–1 MPa), where Li diffusivity and initial interfacial contact may control accessible capacity, compared to high pressures (3–10 MPa) where mechanical deformation of Li likely governs stripping behavior. Analysis of impedance spectra collected during stripping shows that additional stack pressure delays the formation of deep, as opposed to lateral, voids in the Li anode. These results provide insights to guide the transition from thick Li foil anodes to anode‐free manufactured SSBs.

Abstract Solid‐state lithium metal batteries (SSLMBs) are hindered by limited ionic conductivity, heterogeneous lithium flux and interfacial instability of solid‐state electrolytes. Herein, we report a hierarchical ion‐transport network formed by confining lithium halides (LiX, X═Cl, Br, I) within the mesoporous cages of MIL‐100(Al), synergistically integrated with a PVDF‐HFP polymer matrix. The 3D interconnected pores (0.5–1 nm) of MIL‐100(Al) not only spatially confine anions via size‐selective sieving but also enable continuous Li⁺ transport through tunable host–guest interactions between the Lewis‐acidic metal nodes and lithium halides. Among these, the LiI‐embedded composite (E‐LiI) exhibits a high Li⁺ transference number (0.88 at 25 °C) and favorable interfacial kinetics, attributed to strong anion coordination and homogeneous Li⁺ plating. Structural characterizations confirm uniform LiX distribution within the MOF framework. In addition, density functional theory (DFT) calculations and COMSOL simulation elucidate halogen‐dependent desolvation energetics and Li+ transport kinetics. SSLMBs employing E‐LiI electrolytes demonstrate exceptional cycling stability (capacity retention ∼100% after 600 cycles at 2C) with high‐voltage cathodes and wide‐temperature adaptability. This work advances the rational design of multi‐scale ion‐conductive frameworks and the pivotal role of lithium halide in regulating Li deposition kinetics, offering a transformative strategy for high‐energy‐density solid‐state battery systems.

With the advantages of high energy density and high safety factor, solidstate batteries have gradually become the focus of people's attention and research in recent years. Lithium dendrites are a key factor affecting battery safety and service life, and in severe cases, battery short circuits can occur. Compared with liquid batteries, solid-state batteries rely on solid-state electrolytes with higher mechanical strength, which can effectively inhibit the growth of lithium dendrites, but with the increase of the number of charge-discharge cycles, the dead lithium produced by the incomplete dissolution of lithium dendrites gradually accumulates, and the performance of the battery gradually decreases. In this paper, the problem of dead lithium in solid-state batteries is studied by using COMSOL Multiphysics 6.2 finite element simulation software. Since the current research on dead lithium focuses on phase field models coupled with binary physics, there are few studies on the influence of electrochemical parameters on dead lithium. Therefore, the phase field method is used to simulate the dissolution of lithium dendrites and the formation of dead lithium under the coupling of force-thermal-electrochemical fields. When the heat transfer model is coupled, due to the change of lithium dendrite stress distribution, the difference in the morphology of dead lithium before and after the coupled heat transfer model is further studied by applying external pressure to change the stress. When the coupled mechanical field changes, the morphology of dead lithium before and after the coupled mechanical field is further studied by changing the temperature magnitude. At the same time, the effects of changes in three electrochemical parameters, namely diffusion coefficient, interfacial mobility and anisotropic strength, on the area of dead lithium were also explored. The conclusion shows that when the heat transfer model or mechanical field is coupled into the phase field model, the dendrite dissolution cut-off time and dead lithium area will change. When the base rises at high temperature or when low external pressure or high external pressure is applied, the area of dead lithium decreases. For changing the electrochemical parameters, reducing the diffusion coefficient, increasing the interfacial mobility and reducing the anisotropic strength can effectively reduce the area of dead lithium.

Solid polymer electrolytes (SPEs) offer inherent advantages for battery applications, such as high safety and excellent processability, but their practical use is limited by challenges like low ionic conductivity, subpar mechanical properties, and instability of the electrode/electrolyte interface. Here, novel SPEs are developed by embedding 2D MXenes decorated at the surface with methoxypolyethylene glycol chains into poly(vinylidene fluoride)‐hexafluoropropylene matrices, enhanced with succinonitrile as a plasticizer. This innovative design improves the compatibility of the modified MXene in poly(vinylidene fluoride)‐hexafluoropropylene and, together with the synergistic effects of succinonitrile, promotes the dissociation of lithium salt. The SPE achieves ionic conductivity of 1.49 × 10−4 S cm−1 at 30 °C, and a Li‐ion transference number of 0.59. These results are supported by comprehensive experimental characterization, COMSOL simulations, and DFT calculations. This SPE enables stable and reversible Li plating/stripping for over 2100 h in Li/Li symmetric cells, while fabricated Li/LiFePO4 full cells deliver a notable capacity of 135.4 mAh g−1 with an average Coulombic efficiency of 98.9% after 100 cycles at 0.2 C. Furthermore, the Li/LiNi0.6Co0.2Mn0.2O2 full cells also demonstrate a capacity of 140.5 mAh g−1 after over 200 cycles at 0.5 C, showcasing an impressive capacity retention rate of 99.6%.

Due to challenges in manufacturing composite cathodes with oxide solid electrolytes, new cell concepts are emerging in which the infiltration of solid-polymer electrolyte (SPE) into 3D cathode pore structures improves capacity retention and cycling stability. However, the performance limitation and the resulting practical relevance of such a hybrid concept have not yet been analyzed and discussed. This study investigates the impact of laser-ablated geometric structures on the performance of hybrid solid-state batteries (SSBs). A Doyle–Fuller–Newman modeling approach is developed and parameterized for structured hybrid SSBs that incorporate a PEO/LiTFSI SPE and an LLZO ceramic separator, as well as NMC-811 and Li-metal for the positive- and negative-electrode active materials. Comparison between structured and planar cell designs reveals significant rate capability improvements in structured designs due to reduced diffusion and interfacial charge transfer polarization. A sensitivity analysis of geometric structure parameters shows further potential for performance improvement in terms of specific capacity and energy density. However, current constriction effects in the LLZO separator can deteriorate the rate capability. A more general perspective is then taken by analyzing the impact of changing SPE parameters. An energy density of 128 Wh kg−1 at 1C, and 220 Wh kg−1 at 1C with improved SPE parameters is achieved in the best case, approaching the target of 250 Wh kg−1 , which is currently achieved for conventional Li-ion batteries.

Solid-state electrolytes (SSEs) are the core material of solid-state lithium metal batteries (SLMBs), which are being researched urgently owing to their high energy and safety. Both high ionic conductivity and excellent cycling stability remain the primary goal of solid-state electrolytes. Herein, inspired by K+ /Na+ ion channels in cell membrane of eukaryotes, a novel hollow UiO-66 with biomimetic ion channels based on quasi-solid-state electrolytes (QSSEs) is designed. The hollow UiO-66 spheres containing biomimetic ion channels can spontaneously combine anions and incorporate more lithium ions, creating improved ionic conductivity (1.15 × 10-3 S cm-1 ) and lithium-ion transference number (0.70) at room temperature. The long-term cycling of symmetric batteries and COMSOL simulations demonstrate that this biomimetic strategy enables uniform ion flux to suppress Li dendrites. Furthermore, the Li metal full cells paired with LiFePO4 cathode exhibit excellent cycling stability and rate performance. Consequently, the strategy of designing biomimetic QSSEs opens up a new path for developing high-performance electrolytes for SLMBs.

The development of rapid and stable ion-conductive channels is pivotal for solid-state electrolytes (SSEs) in achieving high-performance lithium metal batteries (LMBs). Covalent organic frameworks (COFs) have emerged as promising Li-ion conductors due to their well-defined channel architecture, facile chemical tunability, and mechanical robustness. However, the limited active sites and restricted segmental motion for Li+ migration significantly impede their ionic conductivity. Herein, a rational design strategy is presented to construct 3D porous COF frameworks (TP-COF and TB-COF) using linear ditopic monomers connected via C─C and C─N linkages. These COFs, integrated with polymer electrolytes, provide enhanced Li+ transport pathways and stabilize lithium anodes in LMBs. The TB-COF, featuring larger pore apertures and abundant ─C═N─ active sites, facilitates superior Li+ conduction (8.89 × 10-4 S cm-1) and a high transference number (0.80) by enhancing lithium salt dissolution. LiF/Li3N-rich SEI enables uniform Li deposition, enabling PEO-TB-COF SSEs to achieve >1000 h stability at 1 mA cm⁻2 while retaining 90% capacity through 800 cycles (0.5 C) in LFP||Li cells. Molecular dynamics simulations and COMSOL Multiphysics modeling reveal that extended Li+ transport channels and reduced interfacial diffusion barriers are key to enhanced performance.

In this paper , a single dimensional solid state lithium(Li)-ion batteries are simulated at different C-rates to analyze the characteristics like discharge curves, electrolyte potential along the thickness of electrolyte and variation of concentration along the electrolyte and positive electrode by using multi-physics simulation software tool, COMSOL. Li-ion batteries can be designed with different cathode materials but every material has its own advantages and disadvantages along with their applications. So, the main focus of this paper is to compare the characteristics of different cathode materials of Li-ion battery at different C-rates with similar design operating parameters.

Ultrathin composite solid‐state electrolytes with ultrathin thicknesses and ultra‐low weight exhibit significant prospects for constructing high‐energy‐density solid‐state sodium metal batteries (SSSMBs). However, composite quasi‐solid‐state electrolytes (CSSEs) based on ceramic powder usually show discontinuous ionic transport channels and uneven agglomeration of the powder, which limits their practical performance. In this work, a 3D continuous self‐supporting Na3.3Mg0.15Zr1.85Si2PO12 (NMZSP) ultrathin ceramic skeleton is sintered and further combined with an in situ UV curing process of trihydroxymethylpropyl triacrylate (TMPTA) to achieve an 18 µm‐thick ultrathin NMZSP ceramic skeleton composite quasi‐solid‐state electrolyte (UNSCE). The introduction of a ceramic skeleton effectively prevents ceramic powder agglomeration. Moreover, the synergistic interaction between the ceramic skeleton and the polymer matrix creates an abundant continuous two‐phase interface, which promotes the selective and rapid transportation of Na+. Therefore, UNSCE demonstrates a high Na+ transference number (0.76). COMSOL simulations confirm that the 3D ceramic skeleton facilitates uniform current density, reducing dendrite formation risks. The Na | UNSCE | Na3V2(PO4)3 cell obtains a capacity retention of 91% after 500 cycles at 1C and a discharge capacity of 83.8 mAh g−1 at 10C. In summary, this work presents a scalable fabrication strategy for high‐performance ultrathin CSSEs based on a non‐inert ceramic skeleton, advancing practical deployment in SSSMBs.

The all-solid-state battery (ASSB) has been hailed as a next-generation battery technology that can overcome the limitations of the conventional lithium-ion battery. Nonetheless, it is far from the commercial-production stage yet, and further research and development are required to successfully deploy it to the mass market. Modeling is an important tool in achieving this goal, particularly in aiding the fundamental understanding of the technology. An important consideration for the ASSB modeling is the interplay between mechanics and electrochemistry. Typical solid-electrolyte and electrode materials are stiff, and the active-material volume changes associated with charging/discharging can induce high stresses in the system. Stress is a tensor quantity composed of hydrostatic (volume change) and deviatoric (shape change) parts. Unfortunately, there is no consensus on how different tensor components should contribute to the Gibbs-free-energy formulation and thereby the coupling with electrochemical thermodynamics. Both the hydrostatic and surface-normal stresses have been used in the literature [1, 2]. We attempt to resolve this by employing Goyal and Monroe’s [3] theoretical framework, which starts from stress and strain tensors to construct the Gibbs free energy. We apply this theory to derive equilibrium-potential expressions for three different experimentally accessible scenarios: (1) electrode under a perpendicular uniaxial load, (2) solid electrolyte under a pair of uniaxial loads on its sides, and (3) solid electrolyte under pure shear. Our analysis shows that (1) the deviatoric contribution to the equilibrium potential is negligibly small in all practical cases and (2) the hydrostatic stress, not the surface-normal stress, is the right stress descriptor to use in ASSB models. These predictions can be compared with future experimental works to further the fundamental knowledge of the thermodynamics of the coupling of electrochemistry and elastic mechanics. References [1] Sethuraman et al. (2010). In Situ Measurements of Stress-Potential Coupling in Lithiated Silicon. Journal of The Electrochemical Society, 157(11), A1253. [2] Ganser et al. (2019). An Extended Formulation of Butler-Volmer Electrochemical Reaction Kinetics Including the Influence of Mechanics. Journal of The Electrochemical Society, 166(4), H167. [3] Goyal, P., & Monroe, C. W. (2017). New Foundations of Newman’s Theory for Solid Electrolytes: Thermodynamics and Transient Balances. Journal of The Electrochemical Society, 164(11), E3647–E3660. Figure 1

A model-based understanding can assist and accelerate developing all-solid-state batteries (ASSB). In addition to chemo-mechanical influences within electrode particles (e.g., NMC) [1-2], a solid electrolyte (e.g., argyrodites) introduces additional interfacial interactions between electrode and electrolyte phases [3-5]. The present research derives and implements a coupled multi-physics finite-element model that captures electrochemical, transport, and structural behaviors of composite electrode structures. The models incorporate concentration-dependent and anisotropic material properties that are based on previously published combinations of experiment and density functional theory (DFT). These include stiffness and fracture toughness, porosity and crystallographic orientation, and operating conditions such as charge/discharge rates and external pressure. Figure 1 illustrates predicted stresses developed during electrode manufacturing. The relatively complex cathode microstructure is based on replicating scanning electron microscopy (SEM) images [6]. The composite electrode consists of electrode, electrolyte, and pore phases (Fig. 1a). As illustrated in Fig. 1b, the ASSB synthesis process involves applying and removing high compressive pressure, which causes plastic deformation and introduces residual stresses. Figure 1c shows residual von Mises stresses near electrode-electrolyte interfaces that can be on the order of a gigapascal. The synthesis-generated residual stresses serve as initial conditions for modeling the chemo-mechanics during battery cycling. During cell operation, spatially varying Li concentrations cause material deformation and associated stresses. Figure 1d shows predicted crack nucleation and growth during operation. Depending on the stress levels, crack nucleation and growth leads to cell degradation and capacity fade. The models predict interfacial fracture and phase separations using phase-field fracture theory. In phase-field formulation, the sharp cracks are approximated as diffuse cracks using a process-zone. High values of the phase parameter ξ (Fig. 1d) represent cracked surfaces. The structural disintegration and loss of active surface areas increase the tortuous path for Li/Li-ion transport, which eventually manifests as capacity-fade. The simulations are validated using published experimental work. The modeling approach, which combines phase-field and finite-element algorithms, is implemented using the COMSOL Multiphysics software. The models are expected to inform microstructure/manufacturing design and optimal operating conditions that improve cycling performance and limit/prevent mechanical damage. [1] K. Taghikhani, P.J. Weddle, J.R. Berger, and R.J. Kee. Modeling coupled chemo-mechanical behavior of randomly oriented NMC811 polycrystalline Li-ion battery cathodes. J. Electrochem. Soc., 168(8):080511, 2021. [2] R. Xu, Y. Yang, F. Yin, P. Liu, P. Cloetens, Y. Liu, F. Lin, and K. Zhao, Heterogeneous damage in Li-ion batteries: experimental analysis and theoretical modeling. J. Mech. Phys. Solids, 129, 160, 2019. [3] K. Taghikhani, P.J. Weddle, R.M. Hoffman, J.R. Berger, and R.J. Kee. Electro-chemo-mechanical finite-element model of single-crystal and polycrystalline NMC cathode particles embedded in an argyrodite solid electrolyte. Electrochim. Acta, 460:142585, 2023. [4] A. Bielefeld, D.A. Weber, R. Rueß, V. Glavas, and J. Janek. Influence of lithium ion kinetics, particle morphology and voids on the electrochemical performance of composite cathodes for all-solid-state batteries. J. Electrochem. Soc., 169(2):020539, 2022. [5] P. Minnmann, F. Strauss, A. Bielefeld, R. Ruess, P. Adelhelm, S. Burkhardt, S.L. Dreyer, E. Trevisanello, H. Ehrenberg, T. Brezesinski, F.H. Richter, and J. Janek. Designing cathodes and cathode active materials for solid-state batteries. Adv. Energy Mater., 12(35):2201425, 2022. [6] C. Doerrer, I. Capone, S. Narayanan, J. Liu, C.R.M. Grovenor, M. Pasta, and P.S. Grant. High energy density single-crystal NMC/Li6PS5Cl cathodes for all-solid-state lithium-metal batteries. ACS Appl. Mater. & interfaces, 13(31):37809–37815, 2021. Figure 1

Lithium Metal Anodes (LMAs) have generated significant interest for use in solid-state batteries (SSBs) due to their high theoretical specific capacity. Nonetheless, issues such as dendrite growth (1) and cell failure caused by lithium loss with solid polymer electrolytes (SPEs) (2) of decent ionic conductivities have hindered widespread commercialization. In this work, we report the electrochemical characterization of symmetric Li- SPE– Li cells using thermoplastic vulcanizate (TPV) electrolytes comprised of: PCL:HNBR LiTFSI. Full plating of the lithium metal (LiM) electrode was achieved at 100 μA.cm-2 during constant polarization in pressurized pouch cells. Complete polarization was confirmed through ex-situ analysis by scanning electron microscopy (SEM) with SEM images showing that no dendrites were formed at this current density. Furthermore, cell polarization performed at higher current densities allowed lithium diffusion in the TPV electrolyte to be calculated using the Sand Equation (3, 4). Lithium diffusion was found to be 1.7 x 10-8 cm2.s-1 at 60 °C, which was consistent with other published values (5). The calculated threshold current density (j*) of the corresponding symmetric Li cell was approximately 200 μA.cm-2, confirming the cell failures due to dendrite growth and short circuiting that were observed in the system above this current density. This j* provides valuable information regarding the design of a full cell as the operation current density would be driven by the Li-SPE interface limitation. To this end, 100 cycles were performed in Li-Li symmetric cells with the TPV electrolyte without failure at currents below j* with 0.1 mAh.cm-2 of charge being transferred per cycle, while a charge of 0.5 mAh.cm-2 resulted in rapid cell failure. These findings emphasize the need for current densities and charge references in symmetric Li-Li cells and cells employing solid electrolytes. C. Monroe, J. Newman, The Impact of Elastic Deformation on Deposition Kinetics at Lithium/Polymer Interfaces. Journal of The Electrochemical Society 152, A396 (2005). L. Caradant et al., Effect of Li+ Affinity on Ionic Conductivities in Melt-Blended Nitrile Rubber/Polyether. ACS Applied Polymer Materials 2, 4943-4951 (2020). L. Stolz, G. Homann, M. Winter, J. Kasnatscheew, The Sand equation and its enormous practical relevance for solid-state lithium metal batteries. Materials Today 44, 9-14 (2021). D. Devaux et al., Effect of Electrode and Electrolyte Thicknesses on All-Solid-State Battery Performance Analyzed With the Sand Equation. Frontiers in Energy Research 7, (2020). T. Meyer, T. Gutel, H. Manzanarez, M. Bardet, E. De Vito, Lithium Self-Diffusion in a Polymer Electrolyte for Solid-State Batteries: ToF-SIMS/ssNMR Correlative Characterization and Modeling Based on Lithium Isotopic Labeling. ACS Applied Materials & Interfaces 15, 44268-44279 (2023).

In recent years, demand for rechargeable batteries for electric vehicles and energy storage systems has been growing. In particular, Lithium-ion Batteries (LiB) have various advantages such as high energy density and output density, high voltage, and excellent cycle characteristics, but they use flammable organic electrolyte, which poses a safety problem due to the risk of ignition. In addition, as demand for LiB increases, there is a need to further improve their performance. Therefore, All-Solid-State Batteries (ASSB) are attracting attention as a next-generation storage battery that can replace LiB. ASSB do not use flammable organic electrolyte, but non-flammable inorganic electrolyte, which is thought to improve safety, enable a layered structure, increase capacity, and solve other issues. In a conventional battery using electrolyte, the active material (AM) is completely covered by the electrolyte, whereas in an ASSB, the AM and solid electrolyte (SE) are solid materials, so it is important to handle the effects of solid-solid interface contact and microstructure, and it is necessary to solve the problem of electrode layer contact area. The particle shape of the AM affects the reaction field area and ionic conduction pathways. From the viewpoint of the reaction area, the gap between the AM and the SE inhibits the insertion and desorption of Li+, and from the viewpoint of the ionic conduction pathway, the gap between the SE inhibits the conduction pathway of Li+. In this study, we elucidated the effect of particle shape on battery performance in the anode of ASSB, and proposed a guideline for the optimal design of new materials. The discrete element method (DEM) is a time-evolving method for solving the motion of solid particles based on the equations of motion for translation and rotation. It calculates the forces acting on the particles by assuming springs and dashpots that represent elastic and viscous damping between the particles. In addition, plastic deformation is reflected by considering dashpots between particles [1]. After the electrode layer was created by DEM, tortuosity and contact area were obtained. Multi-Network Model (MNM) [2] was used in the electrochemical calculations. In MNM, AM–AM, SE–SE, and AM–SE particle networks were constructed, and electronic conduction, ionic conduction, ion diffusion, and interfacial electrode reactions were calculated. The analytical equations were solved based on Newman's theory of porous electrodes [3] by coupling the Li concentration in AM, AM electronic potential, electrolyte ion potential, and electrochemical reactions. The Li concentration in AM was determined from the diffusion equation, the electron and ionic potentials were determined to satisfy the electroneutrality condition, and the electrochemical reaction was determined from the Butler-Volmer equation. By changing the particle shapes in the ASSB electrode structure using DEM, contact area and tortuosity of each particle shape were quantitatively evaluated. The results of the electrochemical calculations using the results obtained in this study were reflected in MNM, suggesting that the relationship between contact area and tortuosity of the particle shape influences the battery performance. Acknowledgment This study was supported by JST–Mirai Program(JPMJMI24G1), Japan. References [1] M. So, G.Inoue et al., J. Electrochem. Soc., 168 030538 (2021). [2] R. Hirate et al., MATEC Web of Conferences, 333, 17002 (2021). [3] G. M. Goldin et al., Electrochim. Acta, 64, 118 (2012).

No abstract available

All-solid-state batteries (ASSBs) have garnered significant interest as a promising alternative to conventional lithium-ion batteries, offering improved safety, higher energy density, longer lifespan, faster charging and wider operating temperature range. A key advantage of ASSBs is the use of solid electrolytes (SE), which eliminate the risks associated with flammable liquid electrolytes. However, the complex electrochemical behavior and multi-scale nature of ASSBs pose challenges in designing and optimizing their performance. This study employs Discrete Element Method (DEM) particle-based models to better understand degradation behavior of ASSBs by considering electrochemical reaction, mass and charge transfer, intercalation expansion and material deformation Our simulations were developed in MATLAB and were performed on a half-cell configuration comprising a SE-layer and an anode electrode. The anode electrode was composed of a particle mixture containing active material (AM) and SE. In our simulations, Si was employed as AM, which experiences substantial intercalation expansion during charge cycling 1. Our previously developed DEM model2,3 resolved elastic and plastic deformation of both AM and SE particles which become compressed due to the intercalation expansion. The simulation of intercalation was achieved by integrating the Newman electrochemical model,4 into the DEM mechanical model. Building on our earlier study5, where the Li concentration was resolved within each AM particle, this study is also accounting for the Li-ion potential within each SE particle. Interparticle conduction and diffusion were computed by determining the contact area of AM-AM and SE-SE contacts, which were affected by the compression of the electrode. The electrochemical reaction was calculated at the AM-SE interface using the Butler-Volmer equation, and in addition the influence of compressive stress on the reaction6 was included. Figure 1(a) depicts the Li concentration and Li-ion potential distribution within the half-cell during charging at different states of charge (SOC), while Figure 1(b) provides a 3D view of the distributions at a SOC of 50%. A considerable expansion of the Si anode is evident. The gradients of Li concentration and Li-ion potential signify significant mass and charge transfer resistance during the charging process. Comparing the distribution of the particles, the anode becomes more porous after the first cycle for the same value of SOC. This effect is attributed to the extensive expansion of the Si anode, leading to plastic compression of the SE layer, which becomes more compact after each cycle. The growing porosity diminishes the contact area between particles, ultimately resulting in the degradation of the half-cell's capacity. In addition to SE-layer compaction, this study aims to investigate several degradation mechanisms and their impact on the performance of ASSBs, including the development of shell voids resulting from AM-SE delamination, crack propagation through SE, and fragmentation of AM. The results of this study provide valuable insights into understanding the effect of mechanical degradation on the performance of ASSBs. By improving our understanding of these mechanisms, we can work towards enhancing the durability and lifespan of ASSBs, ultimately contributing to the development of next-generation energy storage systems. Acknowledgment This work was supported by JSPS KAKENHI Grant-in-Aid for Scientific Research on Innovative Areas, “Science on Interfacial Ion Dynamics for Solid State Ionics Devices, Computational & Data Science” (Gp-A03, grant number 19H05815); and MEXT “Program for Promoting Researches on the Supercomputer Fugaku” (Fugaku battery & Fuel Cell Project), grant number JPMXP1020200301. References M. N. Obrovac and L. Christensen, Electrochem. Solid-State Lett., 7, A93 (2004). M. So, G. Inoue, R. Hirate, K. Nunoshita, S. Ishikawa, and Y. Tsuge, J. Electrochem. Soc., 168, 030538 (2021). M. So, G. Inoue, R. Hirate, K. Nunoshita, S. Ishikawa, and Y. Tsuge, Journal of Power Sources, 508, 230344 (2021). J. Newman and K. E. Thomas-Alyea, Electrochemical Systems, 3rd edition., p. 672, Wiley-Interscience, Hoboken, N.J, (2004). M. So, S. Yano, A. Permatasari, T. D. Pham, K. Park, and G. Inoue, Journal of Power Sources, 546, 231956 (2022). G. Bucci, T. Swamy, S. Bishop, B. W. Sheldon, Y.-M. Chiang, and W. C. Carter, J. Electrochem. Soc., 164, A645 (2017). Figure 1