Critical Current Densities for High-Performance All-Solid-State Li-Metal Batteries: Fundamentals, Mechanisms, Interfaces, Materials, and Applications

All-solid-state lithium batteries (ASSLBs) are considered promising next-generation energy storage devices due to their safety and high volumetric energy densities. However, achieving the key U.S. DOE milestone of a power density of 33 kW L–1 appears to be a significant hurdle in current ASSLBs. One of the main reasons is that advancements in solid electrolyte (SE) conductivity have been prioritized over the critical current density (CCD) when employing an elemental Li anode. Several aspects of Li electrode- and SE interface-based difficulties must be resolved before commercialization. Here, we very deeply analyze some crucial parameters that effectively restrict Li dendrite formation while achieving high CCD. Mechanistic explanations are provided to comprehend the critical relationship between a cell failure and development of Li dendrites. The latest progress is discussed in achieving higher CCD in emerging SE structures, including Li-stuffed garnets, Na superionic conductors (NASICONs), Li sulfides, and lithium phosphorus oxynitride (LiPON). Furthermore, primary strategies for improving CCDs by tailoring SE design and stabilizing interfaces are proposed for advanced ASSLBs.