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All-solid-state batteries based on sulfide solid electrolytes are potential candidates for applications such as electric vehicles. One of the challenges for the realization of the all-solid-state battery is the construction of composite electrodes with favorable lithium and electron conductive pathways. Here, we prepared an argyrodite type Li6PS5Cl-based solid electrolyte (LiPSCl)-coated graphite (Gr:LiPSCl, 64:36 weight ratio) by a dissolution-reprecipitation process and investigate its use as anode material for all-solid-state batteries. The addition of a carbon additive (acetylene black, 0.5, 1 and 2 weight ratio) to LiPSCl-coated graphite to form favorable electronic conductive pathways in the negative electrode was also investigated. The all-solid-state half-cell constructed using the argyrodite-coated graphite and carbon additive in 100:1 weight ratio exhibited a discharge capacity of 335 and 372 mAh g−1 at a C-rate of C/8 and at 25 °C and 100 °C, respectively. The electrochemical performance of the all-solid-state cell at different C-rates was evaluated at 100 °C. A relatively high discharge capacity of 276 mAh g−1 was retained at the high C-rate of 2C. Highlights: Argyrodite solid electrolyte coating on graphite by solution process. Argyrodite-coated graphite as anode material for all-solid-state lithium batteries. Graphite all-solid-state cells with high C-rate capability. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) are widely used in portable electronic devices, electric vehicles and large scale energy storage, due to their considerable energy density, low cost and long cycle life. However, traditional liquid batteries suffer from safety problems such as leakage, thermal runaway and even explosion. Part of the issues are caused by lithium dendrites puncturing the liquid electrolyte during cycling. In order to achieve the objective of higher safety and energy density, a rigid solid-state electrolyte (SSE) is proposed instead of liquid electrolyte (LE). Thereinto, sulfide SSEs have received of the most attention due to their high ionic conductivity. Among all the sulfide SSEs, argyrodite SSEs are considered to be one of the most promising solid-state electrolytes due to their high ionic conductivity, high thermal stability and good processablity. On the other hand, lithium metal is an ideal material for anode because of its high specific energy, low potential and large storage capacity. However, interfacial problems between argyrodite SSEs and the anode (interfacial reactions, lithium dendrites, etc.) are considered to be important factors affecting their availability. In this mini review, we summarize the behavior, properties and problems arising at the interface between argyrodite SSEs and anode. Strategies to solve interface problems and stabilize interfaces in recent years are also discussed. Finally, a brief outlook about argyrodite SSEs is presented.

Bulk-type solid-state batteries (SSBs) composed of lithium thiophosphate superionic solid electrolytes (SEs) and high-capacity cathode active materials (CAMs) have recently attracted much attention for their potential application in next-generation electrochemical energy storage. However, compatibility issues between the key components in this kind of battery system are difficult to overcome. Here, we report on a protective cathode coating that strongly reduces the prevalence of detrimental side reactions between CAM and SE during battery operation. This is demonstrated using preformed HfO 2 nanoparticles as a secondary particle coating for a layered Ni-rich oxide CAM, LiNi 0.85 Co 0.1 Mn 0.05 O 2 (NCM85). The preparation of a stable dispersion of the HfO 2 nanoparticles enabled the deposition of a uniform coating of thickness ≤11 nm. When incorporated into Li 6 PS 5 Cl-based, pellet-stack SSBs, the coated NCM85 showed superior performance in terms of reversibility, cell capacity, longevity, and rate capability over its uncoated counterpart. The effectiveness of the protective coating in mitigating electro-chemo-mechanical degradation was investigated using a suite of physical and electrochemical characterization techniques. In addition, the adaptability to wet processing of the coated NCM85 is demonstrated in slurry-cast SSBs and liquid-electrolyte-based Li-ion cells.

Li-ion batteries are the key stones of electric vehicles, but with the emergence of solid-state Li batteries for improving autonomy and fast charging, the need for mastering the solid electrolyte (SE)/electrode material interfaces is crucial. All-solid-state-batteries (ASSBs) suffer from long-term capacity fading with enhanced decomposition reactions. So far, these reactions have not been extensively studied in Li 6 PS 5 Cl-based systems because of the complexity of overlapping degradation mechanisms. Herein, those reactions are studied in depth. We investigated their effects under various operating conditions (temperature, C-rate, voltage window), types of active materials, and with or without carbon additives. From combined resistance monitoring and impedance spectroscopy measurements, we could decouple two reactions (NMC/SE and VGCF/SE) with an inflection dependent on the cutoff potential (3.6 or 3.9 V vs Li-In/In are studied) on charge and elucidate their distinct repercussions on cycling performances. The pernicious effect of carbon additives on both the first cycle and power performances is disclosed, so as its long-term effect on capacity retention. As a mean to resolve these issues, we scrutinized the benefits of a coating layer around NMC particles to prevent high potential interactions, minimize the drastic loss of capacity observed with bare NMC, and simply propose to get rid of carbon additives. Altogether, we hope these findings provide insights and novel methodologies for designing innovative performing solid-state batteries.

Lithium-ion batteries (LIBs) are widely used in portable electronic devices, electric vehicles and large scale energy storage, due to their considerable energy density, low cost and long cycle life. However, traditional liquid batteries suffer from safety problems such as leakage, thermal runaway and even explosion. Part of the issues are caused by lithium dendrites puncturing the liquid electrolyte during cycling. In order to achieve the objective of higher safety and energy density, a rigid solid-state electrolyte (SSE) is proposed instead of liquid electrolyte (LE). Thereinto, sulfide SSEs have received of the most attention due to their high ionic conductivity. Among all the sulfide SSEs, argyrodite SSEs are considered to be one of the most promising solid-state electrolytes due to their high ionic conductivity, high thermal stability and good processablity. On the other hand, lithium metal is an ideal material for anode because of its high specific energy, low potential and large storage capacity. However, interfacial problems between argyrodite SSEs and the anode (interfacial reactions, lithium dendrites, etc.) are considered to be important factors affecting their availability. In this mini review, we summarize the behavior, properties and problems arising at the interface between argyrodite SSEs and anode. Strategies to solve interface problems and stabilize interfaces in recent years are also discussed. Finally, a brief outlook about argyrodite SSEs is presented., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Pang, Gan, Xia, Huang, He and Zhang.)

All-inorganic solid-state batteries (SSBs) currently attract much attention as next-generation high-density energy-storage technology. However, to make SSBs competitive with conventional Li-ion batteries, several obstacles and challenges must be overcome, many of which are related to interface stability issues. Protective coatings can be applied to the electrode materials to mitigate side reactions with the solid electrolyte, with lithium transition metal oxides, such as LiNbO 3 or Li 2 ZrO 3 , being well established in research. In addition, it has been recognized lately that carbonates incorporated into the coating may also positively affect the interface stability. In this work, we studied the effect that surface carbonates in case of Li 2 ZrO 3 -coated Li 1+ x (Ni 0.6 Co 0.2 Mn 0.2 ) 1- x O 2 (NCM622) cathode material have on the cyclability of pellet stack SSB cells with Li 6 PS 5 Cl and Li 4 Ti 5 O 12 as a solid electrolyte and an anode, respectively. Both carbonate-rich and carbonate-poor hybrid coatings were produced by altering the synthesis conditions. The best cycling performance was achieved for carbonate-deficient Li 2 ZrO 3 -coated NCM622 due to decreased degradation of the argyrodite solid electrolyte at the interfaces, as determined by ex situ X-ray photoelectron spectroscopy and in situ differential electrochemical mass spectrometry. The results emphasize the importance of tailoring the composition and nature of protective coatings to improve the cyclability of bulk SSBs.