Current challenges and progress in anode/electrolyte interfaces of all-solid-state lithium batteries

Owing to their high energy density, wide operating temperature range, and excellent safety, all-solid-state batteries (ASSBs) have emerged as ones of the most promising next-generation energy storage devices. With the development of highly conductive solid-state electrolytes, ASSBs are no longer mainly limited by the Li-ion diffusion within the electrolyte, and instead, the current bottlenecks are their low Coulombic efficiency (CE) and short cycling life, which are caused by the high resistance at the electrode/electrolyte interfaces. The high chemical/electrochemical reactivity of the Li metal or the Si anodes and the large volume change during the charge-discharge cycle can exacerbate the physical and chemical instability of the interface. Here, we present the distinctive features of the typical high-capacity anode/electrolyte interfaces in ASSBs and summarize the recent works on identifying, probing, understanding, and engineering them. The complex but important characteristics of high-capacity anode/electrolyte interfaces are highlighted, namely the composition, mechanical, electronic, and ionic properties of the electrode particle-electrolyte particle and plate electrode-electrolyte particle interfaces. Additionally, the advanced characterization strategies for effective interfacial analysis are discussed. Finally, combining the electrode interface characteristics of different structures, the strategies for upgrading two different types of high-capacity anode/electrolyte interfaces are summarized, and some perspectives are provided for better understanding and design of the high-performance ASSBs.