Sulfide Electrolyte All-Solid-State Battery Cathode Mott-Schottky Plots

… recent efforts to develop efficient all-solid-state batteries. While material scientists discovered … In this work, we propose an approach, which can be considered as a Mott-Schottky-based …

The space charge layer (SCL) effects were initially developed to explain the anomalous conductivity enhancement in composite ionic conductors. They were further extended to qualitatively as well as quantitatively understand the interfacial phenomena in many other ionic-conducting systems. Especially in nanometre-scale systems, the SCL effects could be used to manipulate the conductivity and construct artificial conductors. Recently, existence of such effects either at the electrolyte/cathode interface or at the interfaces inside the composite electrode in all solid state lithium batteries (ASSLB) has attracted attention. Therefore, in this article, the principle of SCL on basis of defect chemistry is first presented. The SCL effects on the carrier transport and storage in typical conducting systems are reviewed. For ASSLB, the relevant effects reported so far are also reviewed. Finally, the perspective of interface engineer related to SCL in ASSLB is addressed.

… of a cathode in all-solid-state lithium-ion batteries using sulfide-based solid electrolytes is … Electrochemical impedance spectroscopic measurements showed that two charge-transfer …

Abstract Introduction of an interlayer between a cathode and a sulfide solid electrolyte is a well-known method for reducing the interfacial resistance and improving the performance of all-solid-state batteries. However, the mechanism responsible for the interlayer remains unclear because it is difficult to observe the reactions at the nanometer-scale range. In this study, thin-film model interface of LiCoO2/80Li2S·20P2S5 and LiCoO2/Li3PO4/80Li2S·20P2S5 are fabricated by pulsed-laser deposition. The model interfaces are investigated by performing electrochemical measurements and depth-resolved X-ray absorption spectroscopy to clarify the effect of the Li3PO4 interlayer. The results indicate that a reaction product layer forms between the LiCoO2 cathode and the 80Li2S·20P2S5 electrolyte during charge/discharge processes, resulting in high interfacial resistance. Meanwhile, the formation of the reaction product layer can be suppressed by the introduction of a Li3PO4 interlayer.

… microstructure of solid-state cathodes on the battery performance are needed. This work aims to shed light on the charge transport in solid-state sulfur cathodes by determining the …

… electron density. In the calculation of the defects, we fixed the cell parameters at the relaxed values of the defect-free interfaces. We set the system always neutral, and the occupation …

… We adopted LPS as the sulfide electrolyte because of its … resistance observed at the cathode/sulfide interfaces. Comparing … To discuss the transition metal diffusions at cathode/sulfide …

Introducing dielectric materials is a promising approach to mitigate space‐charge‐layer (SCL) formation, which negatively affects the electrochemical performance of sulfide‐based all‐solid‐state batteries (ASSBs). Most previous studies have focused on mitigating SCL formation by introducing dielectric materials, overlooking the fact that significant dielectric properties such as the dipole moment direction and the magnitude of the dielectric constant can influence SCL formation. To clarify the unclear mechanism of dielectric materials mitigating SCL formation, paraelectricity, ferroelectricity, and the magnitude of the dielectric constant are investigated to determine their effect on SCL formation. Paraelectric materials possessing no permanent dipole moment can effectively mitigate the SCL formation better than ferroelectric material with strong permanent dipole moment because of the intrinsic characteristics of the paraelectric material, in which the dipole moment can be aligned along the direction of the electric field applied inside of ASSB. Furthermore, paraelectric materials with a larger dielectric constant have a greater effect in mitigating SCL effect than paraelectric materials with a smaller dielectric constant. Thus, these properties should be considered in cathode‐solid‐electrolyte interface design. This study considers relevant dielectric material characteristics that had not been considered previously, suggesting a new paradigm for optimizing the interfacial resistance of sulfide‐based ASSBs originating from SCL formation.

All-solid-state batteries (ASSBs) possess the advantage of ensuring safety while simultaneously maximizing energy density, making them suitable for next-generation battery models. In particular, sulfide solid electrolytes (SSEs) are viewed as promising candidates for ASSB electrolytes due to their excellent ionic conductivity. However, a limitation exists in the form of interfacial side reactions occurring between the SSEs and cathode active materials (CAMs), as well as the generation of sulfide-based gases within the SSE. These issues lead to a reduction in the capacity of CAMs and an increase in internal resistance within the cell. To address these challenges, cathode composite materials incorporating zinc oxide (ZnO) are fabricated, effectively reducing various side reactions occurring in CAMs. Acting as a semiconductor, ZnO helps mitigate the rapid oxidation of the solid electrolyte facilitated by an electronic pathway, thereby minimizing side reactions, while maintaining electron pathways to the active material. Additionally, it absorbs sulfide-based gases, thus protecting the lithium ions within CAMs. In this study, the mass spectrometer is employed to observe gas generation phenomena within the ASSB cell. Furthermore, a clear elucidation of the side reactions occurring at the cathode and the causes of capacity reduction in ASSB are provided through density functional theory calculations.

All-solid-state batteries (ASSBs) are poised to transform electrochemical energy storage, yet their performance remains critically limited by high interfacial impedance. A central origin of this bottleneck is the space charge...

Interfacial instability between Li‐metal anode (LMA) and inorganic solid‐state electrolyte (SSE) is a critical issue in all‐solid‐state Li‐metal batteries (ASSLBs). Previous studies have focused on interface modification methodology to achieve long‐term cycling stability in ASSLBs. However, strategy establishment without an in‐depth understanding of the LMA–SSE interface is limited to a phenomenological solution. Also, the fact that rechargeable batteries are operated by behavior of charges inside electric field is frequently overlooked. Here, it is demonstrated for the first time that interface modeling based on energy band theory does effectively overcome the intrinsic vulnerability of SSE to LMA. The interfacial deterioration, due to undesirable electron transport from LMA to the SSE surface, is precluded by a titanium compound self‐induced interlayer (TSI), which forms an interfacial energy barrier. The Li symmetric cell with a TSI successfully maintains its constant overpotential over 1000 cycles and the significantly reduced impedance, whereas the cell having no interface modification exhibits erratic voltage profiles and is easily failed by repetitive charge–discharge process. This newly introduced approach is an informative tool to substantially reinforce the fundamental understanding of interfacial phenomena in all‐solid‐state batteries. Furthermore, rigorous stability requirements of automotive applications are expected to be fulfilled by the innovative interface modification.

… , and trends in interfacial band alignment analyses are then used to propose an interface-compatible interlayer coating to prevent undesired interfacial decomposition reactions. These …

High interfacial resistance between electrode and solid electrolyte (SE) is one of the major challenges for the commercial application of all-solid-state batteries (ASSBs), and coating at the interface is an effective way for decreasing the resistance. However, microscopic electrochemistry especially for the electrochemical potential and the distribution of Li+ at the interface has not been well established yet, impeding the in-depth understanding of interfacial Li+ transport. Herein, we have introduced a potential energy profile for Li+, ηLi+, and demonstrated that the interfacial ηLi+ can be evaluated from the calculated interfacial Li vacancy formation energy or the bulk vacancy formation energy and the interface band alignment. Through computational analysis of the representative LiCoO2 cathode/LiNbO3 coating/β-Li3PS4 SE interfaces using the novel interface structure prediction scheme based on the CALYPSO method, we found that ηLi+ at the LiCoO2/β-Li3PS4 interface is highly disordered under the influence of the interface reconstruction and is rather electronic conductive. Insertion of LiNbO3 coating can effectively decrease the preference of ion mixing. Besides, the appropriate changes in band alignments lead to a decrease of difference in the interfacial ηLi+ and lower resistances at the interfaces. The results provide a reliable explanation for the effectiveness of the coating layer observed experimentally. Furthermore, our study provides a guidance for the future simulation of the microscopic electrochemistry at the electrode/SE interfaces in ASSBs.

Material characterization that informs research and development of batteries is generally based on well-established ex situ and in situ experimental methods that do not consider the band structure. This is because experimental extraction of structural information for liquid-electrolyte batteries is extremely challenging. However, this hole in the available experimental data negatively affects the development of new battery systems. Herein, we determined the entire band structure of a model thin-film solid-state battery with respect to an absolute potential using operando hard X-ray photoelectron spectroscopy by treating the battery as a semiconductor device. We confirmed drastic changes in the band structure during charging, such as interfacial band bending, and determined the electrolyte potential window and overpotential location at high voltage. This enabled us to identify possible interfacial side reactions, for example, the formation of the decomposition layer and the space charge layer. Notably, this information can only be obtained by evaluating the battery band structure during operation. The obtained insights deepen our understanding of battery reactions and provide a novel protocol for battery design. The electronic structure evolution within a battery during cycling can provide crucial cues for its optimization, but insights on operando band structures are extremely challenging to obtain. Here, the authors determine the overall band structure of a model thin-film solid-state lithium battery via operando hard X-ray photoelectron spectroscopy, considering the cathode and anode sides.

High interfacial resistance between a cathode and solid electrolyte (SE) has been a long-standing problem for all-solid-state batteries (ASSBs). Though thermodynamic approaches suggested possible p...

… all-solid-state lithium batteries is still a huge challenge mainly due to the high interfacial resistance present in the entire battery, especially at the interface between the cathode … aligned …

The interfacial resistance between the solid electrolyte (SE) and the cathode of all-solid-state battery can crucially affect its performance. However, the microscopic mechanisms due to which this ...

… cathode slowly degrades in harsh environments. Therefore, the degradation rate of the cathode … An argyrodite-type sulfide SE, LiNi 0·5 Co 0·2 Mn 0·3 O 2 with LiNbO 3 coating as a …