Stability of Halide Electrolyte and High Nickel NCM Positive Electrode

… -voltage charging, indicating interfacial instability. High-resolution transmission electron … /LIC interface and within the LIC electrolyte, causing interfacial contact loss and structural …

… Therefore, to evaluate the thermal stability among charged NCM, LPSCl, … stability of a delithiated Ni-rich charged cathode material (Li 0.533 NCM622) in an ASSB system using halide …

… Halide solid electrolytes have a stable oxidation potential above 4 V, … halide electrolytes with LiCoO2 and Nirich NCM. This paper concludes that halides have electrochemical stability …

Halide‐based solid‐state electrolytes (SSEs), such as Li3InCl6 (LIC), are promising catholytes for all‐solid‐state batteries (ASSBs) because of their high ionic conductivity and high‐voltage stability. However, the aging mechanism between halide SSEs and Ni‐rich cathodes (LiNixCoyMn1−x−yO2, NCM) remain poorly understood. Herein, we investigate the state‐of‐charge (SoC)‐dependent aging behavior of LIC/NCM composite cathodes and reveal a non‐monotonic relationship between SoC and capacity retention after aging. Severe capacity loss occurs under both low‐ and high‐SoC conditions, whereas high capacity retention is achieved after aging at a mid‐range SoC. Comprehensive structural and chemical analyses uncover a synergistic aging mechanism: reductive decomposition of LIC dominates aging at low SoCs, while structural degradation of NCM accounts for aging at high SoCs. Furthermore, an ultrathin coating layer introduced onto the NCM particle surface via atomic layer deposition effectively suppresses interfacial reactions and enhances electrochemical stability, particularly during low‐SoC storage. This work provides mechanistic insights into SoC‐dependent interfacial aging in halide‐based ASSBs and proposes both SoC management and interface engineering strategy to extend their calendar life.

… NCM particles, which presents a detrimental effect on the interface kinetics. Moreover, Ni-rich NCM … This work provides critical insights into advancing halide-based electrolytes in high-…

Halide‐based solid‐state batteries (SSBs) promise high energy density and inherent safety but are constrained by sluggish Li + transport and interfacial instabilities in composite cathodes. Filling voids with fluid organic could provide a compliant interface contact. Yet, halide SSEs are highly reactive with organics. Here, we systematically assess the chemical compatibility of functional organic molecules with halide SSEs and identify perfluoropolyether (PFE) as an exceptionally stable functional organic toward the cost‐effective halide SSEs Li 1.75 ZrCl 4.75 O 0.5 (LZCO). Owing to its low volatility, high wettability, and intrinsic nonflammability, PFE is readily integrated into composite cathodes via dry‐electrode processing without compromising the safety of SSBs. During cycling, PFE scavenges deintercalated Li + and forms an in situ fluoropolyether‐LiF hybrid cathode electrolyte interphase (CEI). This conformal CEI converts discrete point contacts between LiNi 0.82 Co 0.14 Mn 0.04 O 2 (Ni82) and LZCO into continuous areal contacts. Rapid Li + transport through the highly conductive CEI reactivates the previously isolated Ni82 particles. Concurrently, the robust CEI suppresses parasitic reactions including electrolyte oxidation, O 2 evolution, rock‐salt phase formation, Li/Ni mixing, and particle cracking of Ni82. Cathodes containing PFE deliver 206 mAh g −1 at 0.1C and exhibit 83% capacity retention after 1500 cycles at 0.5C. Pouch‐cell validation underscores the scalability of PFE for commercially viable SSBs.

A hierarchically coated halide interface of composite cathodes in all-solid-state batteries improves material compatibility and electrochemical performance.

Two newly emerging materials for application in all‐solid‐state batteries, namely, single‐crystalline Ni‐rich layered oxide cathode and halide solid electrolyte (SE), are of utmost interest because of their superior properties (good microstructural integrity and excellent electrochemical oxidation stability, respectively) to conventional polycrystalline layered oxides and sulfide SEs. In this work, four electrodes employing single‐ or polycrystalline LiNi0.88Co0.11Al0.01O2 (NCA) and Li3YCl6 or Li6PS5Cl0.5Br0.5 are rigorously characterized by complementary analyses. It is shown that the synergy of employing cracking‐free single‐crystalline NCA and oxidation‐tolerable Li3YCl6 can be achieved by considering intercoupled engineering factors that are prone to overlook, such as size, lightness, and mixing of particles. Accordingly, the highest level of performances in terms of discharge capacity (199 mA h g−1 at 0.1C), initial Coulombic efficiency (89.6%), cycling performance (96.8% of capacity retention at the 200th cycle), and rate capability (130 mA h g−1 at 4C) are demonstrated at 30 °C. Severe side reactions occurring at the Li6PS5Cl0.5Br0.5/NCA interfaces are also quantified and probed. Importantly, an overlooked but significant contribution of the side reaction of Li6PS5Cl0.5Br0.5 to the detrimental electrochemo‐mechanical degradation of polycrystalline NCA is revealed for the first time by postmortem scanning electron microscopy and operando electrochemical pressiometry measurements.

All-solid-state lithium batteries (ASSBs) have received increasing attentions as one promising candidate for the next-generation energy storage devices. Among various solid electrolytes, sulfide-based ASSBs combined with layered oxide cathodes have emerged due to the high energy density and safety performance, even at high-voltage conditions. However, the interface compatibility issues remain to be solved at the interface between the oxide cathode and sulfide electrolyte. To circumvent this issue, we propose a simple but effective approach to magic the adverse surface alkali into a uniform oxyhalide coating on LiNi0.8Co0.1Mn0.1O2 (NCM811) via a controllable gas-solid reaction. Due to the enhancement of the close contact at interface, the ASSBs exhibit improved kinetic performance across a broad temperature range, especially at the freezing point. Besides, owing to the high-voltage tolerance of the protective layer, ASSBs demonstrate excellent cyclic stability under high cutoff voltages (500 cycles ~ 94.0% at 4.5 V, 200 cycles ~ 80.4% at 4.8 V). This work provides insights into using a high voltage stable oxyhalide coating strategy to enhance the development of high energy density ASSBs.

Benefiting from the advanced solid-state electrolytes (SSEs), conventional cathodes have been widely applied in all-solid-state lithium batteries (ASSLBs). However, Li-rich Mn-based (LRM) cathodes, which possess enhanced discharge capacities beyond 250 mA h g-1, have not yet been studied in ASSLBs. In this work, the practical application of LRM cathodes in ASSLBs using a high-voltage-stability halide SSE (Li3InCl6, LIC) is reported for the first time. Furthermore, we decipher that the active oxygen released from LRM cathodes at a high operation voltage seriously oxidizes the LIC electrolytes, thus resulting in the large interfacial resistance between cathodes and electrolytes and hindering their industrialized application in ASSLBs. Therefore, surface chemistry engineering of LRM cathodes with an ionic conductive coating material of LiNbO3 (LNO) is employed to stabilize the LRM/LIC interface. Consequently, the LRM-based ASSLBs deliver a high specific capacity of 221 mA h g-1 at 0.1 C and a decent cycle life of 100 cycles. This contribution gives insights into studying the interfacial issues between LRM cathodes and halide electrolytes and sheds light on the application of LRM cathode materials in ASSLBs.

Ni‐rich layered oxides are recognized as one of the most promising candidates for cathodes in all‐solid‐state lithium batteries (ASSLBs) due to their intrinsic merits, such as high average voltage and specific capacity. However, their application is profoundly hindered by sluggish interfacial lithium‐ion (Li+)/electron transfer kinetics, which is primarily caused by surface lithium residues, structural transformation, Li/Ni mixing, H2/H3 phase transition, and microcracks. Furthermore, electro‐chemo‐mechanical failures at the cathode/solid‐state electrolyte (SSE) interface, including interfacial side reactions, space‐charge layer (SCL) formation, and interfacial physical disconnection, accelerate capacity fading. This work provides a systematic overview of these challenges and fundamental insights into utilizing Ni‐rich layered cathodes in ASSLBs. Additionally, several key parameters, such as cost, energy density, pressure, and environmental temperature, are evaluated to meet the specific requirements of ASSLBs for commercial applications. Moreover, the representative modification strategies and future research directions for exploring advanced Ni‐rich layered cathode‐based ASSLBs are outlined. This review aims to provide a comprehensive understanding and essential insights to expedite the application of Ni‐rich layered cathodes in ASSLBs.

Halide solid electrolytes (SEs) are attracting strong attention as one of the compelling candidates for the next‐generation of inorganic SEs due to their high ionic conductivity. Nevertheless, unsatisfactory high‐voltage stability restricts the further applications of halide SEs. Herein, the anion‐engineering of F−/O2− is evolved to construct the high‐voltage stable zirconium‐based halide superionic conductors (Li2.5ZrCl5F0.5O0.5, LZCFO). Benefiting from the thermodynamic/kinetic high‐voltage stability of F‐containing SE and the disordered localized structure introduced by O2−, LZCFO displays a practical electrochemical limit of 4.87 V versus Li/Li+ and an ionic conductivity of 1.17 mS cm−1 at 30 °C. With LZCFO and NCM955, the all‐solid‐state lithium battery exhibits a high discharge capacity of 207.1 mAh g−1 at 0.1C and a capacity retention of 81.2% after 500 cycles at 0.5C. The interfacial characterization further demonstrates the formation of the F‐rich cathode–electrolyte interphase (CEI), which inhibits side reactions between the cathode and the SE and boosts excellent cycling stability. This work affords fresh insights on the engineering of SEs with high‐voltage stability, high ionic conductivity, and stable CEI in all‐solid‐state lithium batteries.

Residual lithium compounds (RLCs) in all‐solid‐state batteries (ASSBs) employing Ni‐rich cathode materials (LiNixCoyMnzO2, NCM) are traditionally viewed either as ionically and electronically insulating layers hindering electrochemical performance or as protective buffer layers enhancing cycling stability. In this study, a beneficial role of Li2CO3 in ASSBs featuring an oxyhalide‐based AlOCl‐2LiCl (LAOC) solid‐state electrolyte (SSE) is revealed. ASSBs containing NCM with residual Li2CO3 demonstrate superior electrochemical performance compared to those treated with a washing pretreatment to remove Li2CO3. Solid‐state nuclear magnetic resonance (ssNMR) spectroscopy shows that Li2CO3 facilitates spontaneous Li+ exchange at multiple sites within the LAOC SSE. This leads to faster ion mobility and shorter relaxation times at various lithium sites, indicating enhanced ion transport and improved interface dynamics. Moreover, the beneficial effects of Li2CO3 are confirmed in other halide‐based ASSBs. This study uncovers an unexpected role for Li2CO3 in halide‐based ASSBs, offering insights that may inspire further exploration of RLCs with functional properties for improving ASSBs performance.

All-solid-state batteries (ASSBs) with high-nickel cathodes face significant interfacial challenges. While single-crystalline (SC) cathodes are known to mitigate issues in liquid electrolytes, their advantage in solid-state systems is debatable. Here,...

… behavior of the mixed-halide Li3YBr3Cl3 (LYBC) SE induced … different from that of single halide systems, and we tracked … the cathode and electrolyte, and demonstrate that all-solid-state …

Halide solid‐state electrolytes (HSSEs) have gained significant attention as key components for all‐solid‐state lithium ion batteries due to their notable advantages, including high ionic conductivity (> 1 mS cm −1 ), wide electrochemical window (> 4 V vs. Li/Li⁺), and good compatibility with high‐voltage cathodes. Despite progress, major challenges such as ionic conductivity, air stability, and interface compatibility still remain. This review systematically summarizes their representative classifications (e.g., Li a ‐M‐X 8 , Li a ‐M‐X 6 , Li a ‐M‐X 4 , Li a M b O c X d , M = In, Y, Al…; X = Cl, F, Br…), synthesis methods (e.g., solid phase, liquid phase, gas phase), and ion conduction mechanisms (e.g., vacancy‐driven transport). The merits and demerits of different synthesis methods are analyzed, and the factors affecting ion conductivity are also discussed. Moreover, various modification strategies (e.g., structure optimization, doping, and surface coating) are analyzed to address the above issues. Meanwhile, research guidelines for developing advanced HSSEs are also proposed. Additionally, we provide a systematic outlook on HSSEs in terms of novel synthesis methods and interface modification technologies (such as plasma and supercritical fluid technologies), high‐precision characterization methods for interface components (such as solid‐state nuclear magnetic resonance), artificial intelligence (AI)‐assisted mechanism analysis, and material synthesis. This review offers new research insights into the design and development of advanced solid‐state electrolytes for energy storage.

Solid electrolytes (SEs) are central components that enable high-performance, all-solid-state lithium batteries (ASSLBs). Amorphous SEs hold great potential for ASSLBs because their grain-boundary-free characteristics facilitate intact solid-solid contact and uniform Li-ion conduction for high-performance cathodes. However, amorphous oxide SEs with limited ionic conductivities and glassy sulfide SEs with narrow electrochemical windows cannot sustain high-nickel cathodes. Herein, we report a class of amorphous Li-Ta-Cl-based chloride SEs possessing high Li-ion conductivity (up to 7.16 mS cm-1) and low Young's modulus (approximately 3 GPa) to enable excellent Li-ion conduction and intact physical contact among rigid components in ASSLBs. We reveal that the amorphous Li-Ta-Cl matrix is composed of LiCl43-, LiCl54-, LiCl65- polyhedra, and TaCl6- octahedra via machine-learning simulation, solid-state 7Li nuclear magnetic resonance, and X-ray absorption analysis. Attractively, our amorphous chloride SEs exhibit excellent compatibility with high-nickel cathodes. We demonstrate that ASSLBs comprising amorphous chloride SEs and high-nickel single-crystal cathodes (LiNi0.88Co0.07Mn0.05O2) exhibit ∼99% capacity retention after 800 cycles at ∼3 C under 1 mA h cm-2 and ∼80% capacity retention after 75 cycles at 0.2 C under a high areal capacity of 5 mA h cm-2. Most importantly, a stable operation of up to 9800 cycles with a capacity retention of ∼77% at a high rate of 3.4 C can be achieved in a freezing environment of -10 °C. Our amorphous chloride SEs will pave the way to realize high-performance high-nickel cathodes for high-energy-density ASSLBs.

… The sulfide electrolyte-based all-solid-state batteries with high-nickel layered oxide cathodes … Here, we successfully synthesized Li 3 InCl 6 (LIC) halide electrolytes through ball-milling …

All-solid-state lithium batteries (ASSLBs) combining the cost-controllable ultrahigh nickel cathode are receiving considerable attention due to their great potential for good safety under high energy density. Improving the interfacial stability...

… cathode and the electrolyte. Also, the absence of long-range order in NCHSSEs creates an abundance of “free volume” within the material. This space allows for better accommodation …

All‐solid‐state lithium batteries (ASSLBs) are expected to revolutionize large‐scale energy storage and electric vehicles due to their exceptional safety and high energy density. Central to this technology is the development of solid electrolytes, with halide electrolytes emerging as highly promising candidates, offering high ionic conductivity, robust electrochemical stability and excellent mechanical properties. Since the breakthrough discovery of Li3YCl6 in 2018, research on halide electrolytes has entered a new era. However, despite continuous research efforts, practical challenges persist in their application, including the need to further enhance ionic conductivity, improve moisture resistance, and achieve better compatibility with electrode materials. This review provides a comprehensive overview of recent progress and ongoing challenges in halide electrolytes, examining crystal structures, conduction mechanisms, and scalable synthesis techniques. Various modification strategies are also explored aimed at boosting ionic conductivity and electrochemical stability, with a particular focus on improving interface stability. Finally, future perspectives are outlined for designing high‐performance halide electrolyte materials, offering guidance for ongoing research efforts toward their commercial application in ASSLBs.

All‐solid‐state batteries (ASSBs) are a pivotal advancement for next‐generation energy storage, addressing the safety and energy density limitations of conventional lithium‐ion systems. Among various solid‐state electrolytes (SSEs), halide‐based SSEs have emerged as particularly promising candidates due to their unique combination of high ionic conductivity (0.1–10 mS cm−1), exceptional electrochemical stability (>4.5 V), and favorable mechanical properties. In contrast to polymer SSEs (limited by low ionic conductivity), oxide SSEs (requiring energy‐intensive processing), and sulfide SSEs (exhibiting moisture sensitivity and high cost), halide SSEs offer a more balanced performance profile, making them highly suitable for commercial applications. This perspective highlights halide SSEs as a key enabler for the commercialization of ASSBs, not only due to their superior material properties but also because of their advantages in scalable synthesis and industrial compatibility. Specifically, halide SSEs can be processed at room temperatures and pressures, and exhibit better interfacial compatibility with high‐voltage cathodes. These attributes significantly simplify the transition from lab‐scale research to pilot‐scale production, reducing both energy consumption and manufacturing complexity. Furthermore, a unified lab‐to‐pilot framework is proposed that integrates fundamental electrochemistry with scalable engineering practices for halide SSEs. A 2D evaluation system is also introduced to guide the selection of optimal application scenarios for ASSBs. By addressing critical challenges such as moisture sensitivity, interfacial degradation, and mechanical brittleness, halide SSEs are positioned as the most manufacturable pathway toward the commercialization of ASSBs for electric vehicles and grid‐scale storage. This work is the first to provide a comprehensive strategy perspective on halide‐based ASSB pilot lines, offering practical insights into material selection, process optimization, and industrial scalability.

A review of halide solid-state electrolytes: from material properties (conductivity, stability, and mechanics) to all-solid-state lithium battery performance.

Since the electrochemical potential of lithium metal was systematically elaborated and measured in the early 19th century, lithium-ion batteries with liquid organic electrolyte have been a key energy storage device and successfully commercialized at the end of the 20th century. Although lithium-ion battery technology has progressed enormously in recent years, it still suffers from two core issues, intrinsic safety hazard and low energy density. Within approaches to address the core challenges, the development of all-solid-state lithium-ion batteries (ASSLBs) based on halide solid-state electrolytes (SSEs) has displayed potential for application in stationary energy storage devices and may eventually become an essential component of a future smart grid. In this Review, we categorize and summarize the current research status of halide SSEs based on different halogen anions from the perspective of halogen chemistry, upon which we summarize the different synthetic routes of halide SSEs possessing high room-temperature ionic conductivity, and compare in detail the performance of halide SSEs based on different halogen anions in terms of ionic conductivity, activation energy, electronic conductivity, interfacial contact stability, and electrochemical window and summarize the corresponding optimization strategies for each of the above-mentioned electrochemical indicators. Finally, we provide an outlook on the unresolved challenges and future opportunities of ASSLBs.

Halide solid electrolytes have recently emerged as a promising option for cathode‐compatible catholytes in solid‐state batteries (SSBs), owing to their superior oxidation stability at high voltage and their interfacial stability. However, their day‐ to month‐scale aging at the cathode interface has remained unexplored until now, while its elucidation is indispensable for practical deployment. Herein, the stability of halide solid electrolytes (e.g., Li3InCl6) when used with conventional layered oxide cathodes during extended calendar aging is investigated. It is found that, contrary to their well‐known oxidation stability, halide solid electrolytes can be vulnerable to reductive side reactions with oxide cathodes (e.g., LiNi0.8Co0.1Mn0.1O2) in the long term. More importantly, the calendar aging at a low state of charge or as‐fabricated state causes more significant degradation than at a high state of charge, in contrast to typical lithium‐ion batteries, which are more susceptible to high‐state‐of‐charge calendar aging. This unique characteristic of halide‐based SSBs is related to the reduction propensity of metal ions in halide solid electrolytes and correlated to the formation of an interphase due to the reductive decomposition triggered by the oxide cathode in a lithiated state. This understanding of the long‐term aging properties provides new guidelines for the development of cathode‐compatible halide solid electrolytes.

… of composite cathodes. From a comparative study using halide and sulfide solid electrolytes (SEs), herein, we reveal the critical degradation factors of halide-SE-based cathodes, which …

As the demand for high energy density and battery safety grows, all‐solid‐state batteries (ASSBs) have garnered considerable attention as promising energy storage systems by removing flammable liquid electrolytes (LEs). Cutting‐edge sulfide inorganic solid electrolytes (ISEs) such as Li10GeP2S12 and Li6PS5Cl have shown high Li+ conductivity comparable to those of LEs. However, the narrow electrochemical stability windows of sulfide ISEs hinder the development of high‐energy density ASSBs with severe interfacial challenges. Recently, halide ISEs such as Li3YCl6 and Li3InCl6 are attracting increasing attention because of their high Li+ ion conductivity, excellent thermal stability, and high oxidative stability above 4 V. These properties are crucial to developing ASSBs with high energy density, and exceptional cycle and rate performances when employing high‐voltage cathode materials. Nevertheless, recent studies have identified severe interfacial challenges in ASSBs utilizing halide ISEs. Moreover, the safety of ASSBs is assumed to be better than conventional LE batteries but studies find the opposite conclusion when certain types of ISEs are employed, which can be attributed to products from side reactions at the interfaces. The objective here is to summarize the interfacial challenges associated with halide ISEs‐based ASSBs that will guide the development of high‐performance and safe ASSBs.

All-solid-state batteries have emerged as a promising technology for energy storage, offering improved safety and potential for higher energy density. Halide-based batteries have gained popularity due to the advantageous characteristics of electrolytes, including decent ion conductivity, good formability, high-voltage stability, and moisture resistivity. Despite the impressive cycle life observed in halide-based batteries under high stack pressures or at elevated temperatures, poor cathode–electrolyte stabilities still pose a significant challenge that results in rapid capacity decay under ambient temperature and low pressure. The poor stability at the halide–anode interface further limits the choice of electrode materials for high-energy applications. This article presents a review of interfacial instability in halide-based solid-state batteries, addressing both the chemical, electrochemical, and mechanical origins of these instabilities at the cathode–electrolyte and anode–electrolyte interfaces. We also discuss state-of-the-art approaches to mitigate interfacial instabilities and highlight their limitations. Finally, we propose perspectives and future directions for resolving interfacial instabilities in halide-based solid-state batteries.

All-solid-state lithium metal batteries (ASSLBs) are promising for high energy and safety. Halide-based solid-state electrolytes, characterized by high ionic conductivity and a notably wide electrochemical window exceeding 4.3 V, hold significant promise for compatibility with high-energy cathodes. However, oxygen in cathodes exhibits a strong tendency to interact with the central metal cation in halide solid-state electrolyte, forming an unstable cathode-electrolyte interface (CEI) and leading to cathodic degradations. Herein, a pre-oxidation strategy is proposed for Y based halide solid-state electrolytes, leveraging oxygen to pre-establish robust Y─O bonds within the halide electrolyte structure Li2YCl2.5Br1.5O0.5 (2LO-0.5). The robust Y─O bonds in 2LO-0.5 effectively hinder uncontrolled oxygen interactions with Y3⁺, which would otherwise lead to the formation of oxidizable YOCl. This stabilization promotes the formation of a thin, stable Y₂O₃-based CEI against LiNi0.83Co0.11Mn0.06O2 (NCM83). Therefore, the ASSLB assembled with 2LO-0.5 and NCM83 demonstrates an initial discharge-specific capacity of 208 mAh g-1 and retained 80.6% of its capacity after 1000 cycles, attributed to stable CEI film derived from pre-oxidized strategy. This work offers new insights for regulating the non-redox reaction between halide solid-state electrolytes and oxide cathodes, promoting the rational design of high-performance halide solid-state electrolytes.

… When paired with an NCM811 cathode, the cell retains 70% capacity after 950 cycles at 4.4 V … with these optimized electrolytes show substantially enhanced cycling stability under high-…

… interphases, thereby constructing a relatively stable interface and promoting uniform Li deposition. The … ASSLBs assembled with these optimized electrolytes gain good electrochemical …

All-solid-state lithium batteries (ASSLBs) offer exceptional energy density and safety, yet interfacial instability at both cathode and anode remains a major challenge. This review pioneers a unified, multiscale framework that...

Li metal offers high capacity and low electrochemical potential; however, its high reactivity leads to unstable solid electrolyte interphase (SEI) formation and dendrite growth. Consequently, Li-halide surface modification has attracted significant attention. Among these approaches, LiCl can suppress electron leakage and stabilize the interface, yet its low Li+ conductivity limits Li-ion transport and nucleation control under high current densities. In this study, to address these limitations, an MgCl2-based thermal conversion reaction was employed to construct a mixed interfacial structure in which a Li-Mg alloy layer and LiCl coexist (Li-Mg/LiCl@Li). This strategy preserves the insulating nature and chemical and electrochemical stability of LiCl, while introducing the high Li-ion diffusivity and lithiophilicity of the Li-Mg alloy, thereby effectively mitigating the unfavorable Li plating behavior observed in conventional LiCl artificial SEI layers that arises from insufficient Li-ion diffusivity under high-current conditions. Furthermore, Li symmetric cells employing Li-Mg/LiCl@Li maintain a low overpotential of ∼28 mV and exhibit stable Li plating and stripping for over 1000 h at 1 mA cm-2/1 mAh cm-2. Postcycling X-ray photoelectron spectroscopy further suggests more effective suppression of electrolyte side reactions relative to LiCl-only electrodes. Moreover, full cells employing a LiNi0.8Co0.1Mn0.1O2 cathode also demonstrate long cycle-life stability and excellent rate performance.

… and electrolyte phases predominantly governs interface stability. Fluorine-containing materials improve the stability and … of the cycled NCM811 after 50 cycles using different electrolytes. …

Intrinsic or interface thermodynamic voltage windows of solid electrolytes are often narrower than the operational voltage range needed by a full battery, thus various interface decomposition reactions can happen in a practical solid‐state battery. Experimentally, it is found that a proper battery design utilizing the reactions can lead to a dynamic evolution from interface instability to stability, giving the so‐called dynamic voltage stability for advanced battery performance. Here, first the state‐of‐the‐art understanding is articulated about how the dynamic voltage stability should be interpreted in physical picture and treated in computation, emphasizing the potential importance of nonequilibrium reaction pathways. The constrained ensemble computational approach is further applied across most types of solid‐state electrolytes to systematically evaluate and compare their dynamic stability voltage windows in response to the mechanical constriction effect. High‐throughput calculations are used to search for coating materials for different interfaces between sulfide, halide, and oxide electrolytes and typical cathode materials with enhanced dynamic voltage stability. A comparison with experiment is given to highlight the value of these computational predictions.

All-solid-state batteries (ASSBs) based on inorganic solid electrolytes (SEs) are one of the most promising strategies for next-generation energy storage systems and electronic devices due to the higher energy density and intrinsic safety. However, the poor solid-solid contact and restricted chemical/electrochemical stability of inorganic SEs both in cathode and anode SE interfaces cause contact failure and the degeneration of SEs during prolonged charge-discharge process. As a result, the increasing interface resistance significantly hinders the coulombic efficiency and cycling performance of ASSBs. Herein, we present a fundamental understanding of physical contact and chemical/electrochemical features of the ASSB interfaces based on mainstream inorganic SEs and summarize the recent work on interface modification. SE doping, optimizing morphology, introduce interlayer/coating layer and utilizing compatible electrode materials are the key methods to prevent the side reactions which are discussed separately in cathode/anode-SE interface We Also highlight the constant extra stack pressure applied during ASSBs cycling, which is important to the electrochemical performance. Finally, our perspectives of interface modification for practical high-performance ASSBs are put forward.

… Electrochemical stability window of Li halide (Li 3 MCl 6 and … It should be noted that interfacial stability of Li 3 MCl 5 F with … However, this exceeds the standard cutoff limit for NCM811 (…

… electrochemical stability of halide SSEs, where the interfacial … After that, we outline the application of halide electrolytes in … with NCM811 is capable of 100 cycles. However, the bilayer …

… 6 electrolyte is … electrolyte paired with NCM811 cathode is evaluated. The results demonstrate that Nb 5+ doping significantly enhances the specific discharge capacity and cycle stability …

… strategies to enhance the interface stability. Finally, we … stability windows of Li-halide and sulfide solid electrolytes. (73) … the NCM811 operating voltage, whereas Li 3 YCl 6 remains …

… electrochemical stability window, a larger band gap, and higher elastic moduli compared to other types of halides. … of lithium halides for applications in high-voltage cathodes through the …

Enabling all-solid-state Li-ion batteries requires solid electrolytes with high Li ionic conductivity and good electrochemical stability. Following recent experimental reports of Li3 YCl6 and Li3 YBr6 as promising new solid electrolytes, we used first principles computation to investigate the Li-ion diffusion, electrochemical stability, and interface stability of chloride and bromide materials and elucidated the origin of their high ionic conductivities and good electrochemical stabilities. Chloride and bromide chemistries intrinsically exhibit low migration energy barriers, wide electrochemical windows, and are not constrained to previous design principles for sulfide and oxide Li-ion conductors, allowing for much greater freedom in structure, chemistry, composition, and Li sublattice for developing fast Li-ion conductors. Our study highlights chloride and bromide chemistries as a promising new research direction for solid electrolytes with high ionic conductivity and good stability.

Over the past few years, halide solid‐state electrolytes (HSSEs) have attracted the attention of researchers, and many reports about HSSEs have been published. Their wide electrochemical window (ECW) and a quite good compatibility with the popular oxide cathode materials make them attractive for practical applications. As a result, HSSEs are exciting candidates for the future generation of all‐solid‐state Li batteries (ASSLBs). In recent years, noticeable efforts have been made to develop novel HSSEs and utilize them in ASSLBs. Herein, a comprehensive update on the progress of HSSEs development and their application in ASSLBs is provided. First, a brief summary of the conductivity of HSSEs and potential synthesis approaches is provided. Next, the moisture and phase stabilities of HSSEs are reviewed separately, and the techniques proposed in the recently published reports to achieve sufficient stabilities are summarized. In addition, the electrochemical stabilities of HSSEs with Li metal anode and oxide cathode materials, from experimental and theoretical points of view, are provided in parallel. Furthermore, the application and progress of HSSEs in high‐voltage ASSLBs are discussed. Finally, new research directions are suggested for the development of scalable HSSEs‐based ASSLBs.

… Li 3 InCl 6 -based halide electrolytes have garnered significant research interest … cathode compatibility, and simple synthesis process. Nevertheless, their limited high-voltage stability …

Lithium metal solid‐state batteries (LMSBs) have attracted extensive attention over the past decades, due to their fascinating advantages of safety and potential for high energy density. Solid‐state electrolytes (SEs) with fast ionic transport and excellent stability are indispensable components in LMSBs. Heretofore, a series of inorganic SEs have been extensively explored, such as sulfide‐ and oxide‐based electrolytes. Unfortunately, they both have difficulty in achieving a satisfactory balance of conductivity and stability, and oxides suffer from a high impedance of grain boundaries, while sulfides encounter poor stability. Halide‐based solid electrolytes are gradually emerging as one of the most promising candidates for LMSBs due to their advantages of decent room temperature ionic conductivity (>10−3 S cm−1), good compatibility with oxide cathode materials, good chemical stability, and scalability. Herein, research and development of the widely studied metal halide SEs including fluorides, chlorides, bromides, and iodides are reviewed, mainly focusing on the structures and ionic conductivities as well as preparation methods and electrochemical/chemical stabilities. And then, based on typical metal halide solid electrolytes, we emphasize the interface issues (grain boundaries, cathode−electrolyte and electrolyte–anode interfaces) that exist in the corresponding LMSBs and summarize the related work on understanding and engineering these interfaces. Furthermore, the typical (or in situ) characterization tools widely used for solid‐state interfaces are reviewed. Finally, a perspective on the future direction for developing high‐performance LMSBs based on the halide electrolyte family is put out.

… between solid electrolyte (SE) and cathode active material in all-solid-state Li-ion batteries (… -type composite cathodes containing Ni-rich Li(Ni, Co, Mn)O 2 (NCM; Ni stoichiometries ≥…

: One approach to increase the energy density of all-solid-state batteries (ASSBs) is to use high-voltage cathode materials. The spinel LiNi 0.5 Mn 1.5 O 4 (LNMO) cathode is one such example, as it offers a high reaction potential (close to 5 V). Moreover, it is a Co-free cathode system, which makes it an environmentally friendly and a low-cost alternative. However, several challenges must be addressed before it can be properly adopted in ASSB technologies. Herein, we reveal that lithium argyrodite (Li 6 PS 5 Cl), a sulfide solid-state electrolyte (SSE), possesses intrinsic chemical incompatibility with the LNMO cathode. We demonstrate the necessity of using a halide SSE, Li 3 YCl 6 (LYC), through careful analysis of the LNMO/SSE interface. Moreover, we emphasize the necessity of applying a protective coating layer to LNMO particles, even when halide SSEs are used. Furthermore, the chemical phenomena involving LYC in the oxidative environment of LNMO are analyzed, including a comparison between coated and uncoated LNMO particles. Experimental methods; ionic and electronic conductivities of LPSCl and LYC; Nyquist plots and corresponding fitted results; experimental data of cathodes and cathode composites, including XRD, powder SEM, FIB-SEM, XPS, HAADF, EIS, and additional electrochemical data (PDF)

… All-solid-state batteries(ASSLBs) as a next … liquid electrolyte. In this study, to improve electrochemical performance of sulfide based ASSLBs, cathode mixture with halide solid electrolyte …

… -crystal Ni-rich cathodes with systematically tuned Ni contents in halide-based ASSLBs. It is … PO 4 coating as a dual chemical–mechanical buffer, enabling the ultra–high-Ni cathodes to …

Abstract Lithium metal chlorides are promising superionic conductors for all‐solid‐state batteries (SSBs) due to their favorable mechanical properties, high ionic conductivity, and good oxidative stability (up to >4.2 V versus Li/Li+). Nonetheless, chloride solid electrolytes (SEs) still undergo electrochemical degradation when paired with high‐voltage cathodes such as LiNi0.85Co0.1Mn0.05O2. A viable strategy to enhance the intrinsic electrochemical stability of chloride electrolytes is to partially substitute Cl with F. By leveraging complementary insights from neutron and X‐ray diffraction, X‐ray absorption spectroscopy, X‐ray photoelectron spectroscopy (XPS), time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS), and electrochemical studies, we investigate the interplay between ionic and electronic conductivity, voltage stability, and overall battery performance of a family of new dual‐halogen SEs—Li2HfCl6−xFx. All‐solid‐state cells utilizing Li2HfCl5.5F0.5 as the electrolyte demonstrate much‐enhanced battery performance compared to Li2HfCl6. This improvement is mainly attributed to the formation of a kinetically stable LiF‐rich cathode electrolyte interphase (CEI), which inhibits detrimental reactions between the cathode and the SE, as revealed by ToF‐SIMS studies. The findings from this study are applicable to other dual‐halogen solid ionic conductors, offering valuable insights into the relationship between intrinsic electrochemical window (IEW), electronic and ionic conductivity, and battery performance in dual‐halogen solid‐state electrolytes.

A deep understanding of the interaction of the surface of cathode materials with solid electrolytes is crucial to design advanced solid-state batteries (SSBs). This is especially true for the new...

Rechargeable batteries have been considered one of the most effective energy storage technologies bridging the renewable energy production and consumption. The further development of rechargeable batteries with characteristics such as high energy density, low cost, safety and a long cycle life is required to meet the ever-increasing energy storage demands. This review highlights the scientific and technological progress of rechargeable batteries achieved by halide-based materials and chemistries, including the use of halide electrodes, bulk and/or surface halogen-doping of electrodes, electrolyte design and additives enabling fast ion shuttle and stable electrode/electrolyte interfaces, and realization of new battery chemistries. A variety of battery chemistries based on monovalent cation, multivalent cation, anion, or dual-ion transfer is covered. This review aims to promote the understanding of halide-based materials and chemistries to stimulate further research and development in the area of high-performance rechargeable batteries. It also offers a perspective on the exploration of new electrochemical energy storage materials and systems.

Understanding the chemical and electrochemical behavior of halide and sulfide electrolytes offers a straightforward and effective approach to improving the interface of halide-based solid-state batteries.