Current Status and Enhancement Strategies for All-Solid-State Lithium Batteries

All-solid-state lithium batteries have received considerable attention in recent years with the ever-growing demand for efficient and safe energy storage technologies. However, key issues remain unsolved and hinder full-scale commercialization of all-solid-state lithium batteries. Previously, most discussion only focused on how to achieve high energy density from the theoretical perspective. Herein, we analyze the real cases of different kinds of all-solid-state lithium batteries with high energy density to understand the current status, including all-solid-state lithium-ion batteries, all-solid-state lithium metal batteries, and all-solid-state lithium–sulfur batteries. First, we propose a general calculation method to visually compare the above battery systems partly due to no normative parameters for solid-state batteries. After then, we discuss and interpret the key parameters and current situation of all-solid-state lithium batteries. Through the summary and analysis of the frontier, one can find that, although some breakthrough has been made in energy density and areal capacity for solid-state batteries, there are still many aspects to be improved such as power density and rate performance. Therefore, in response to the challenges, we propose possible directions for future development, including the ways to prepare different kinds of solid electrolyte films to reduce the proportion of inactive substances in the cell. The advantages and disadvantages are discussed about three typical solid-state electrolyte films (inorganic solid electrolyte, solid polymer electrolyte, and composite solid electrolyte). In addition, potential candidate anodes with high capacity and cathodes with high voltage and/or high capacity are also discussed in details. The combination of lithium metal anodes with ultrahigh capacity and cathodes with both high capacity and high voltage is the current mainstream direction. However, the interface problems have become the most pressing factor on the application. Therefore, we introduce the origin of interfaces and interphases and discuss how to build a stable electrode/solid electrolyte interface. One thing is clear that artificial solid electrolyte interphases and composite solid electrolytes are effective to obtain stable anode/solid electrolyte interfaces, which can prevent lithium from constantly reacting with solid electrolytes, ensure the uniform lithium deposition and prevent the formation of lithium dendrites. For the cathode/solid electrolyte interface, reasonable composite cathodes, multilayer design, and composite solid electrolytes can optimize the electrode and interface for stable cycles at high voltages and high current densities. Furthermore, the contribution of high-throughput computations and machine learning is introduced in accelerating materials screening and development. Among them, progress has been made in solid electrolytes and artificial solid electrolyte interphases through materials genome engineering and machine learning. Finally, we provide some outlook for the future development. We hope that this Account could help understand the current status and inspire more future breakthrough for all-solid-state lithium batteries.