Challenges and prospects of dead Li 0 reactivation in lithium metal batteries

Abstract High-energy-density lithium (Li) metal batteries (LMBs) are promising next-generation energy storage technologies. However, the continuous and irreversible inactive metallic Li (dead Li0) generation severely limits battery lifespans. Notably, reactivating dead Li0 in addition to reducing its formation is also crucial for achieving long-life LMBs. Though prototype strategies (e.g., electrochemical protocols, redox chemistry) have achieved partial reactivation of dead Li0, their feasibility in practical cells remains limited by the large proportion of dead Li0 that persists. Directly reconnecting exposed dead Li0 with electrodes by introducing external electronically conductive materials is a promising solution, yet it fails to achieve the expected reactivation. To achieve efficient reactivation of dead Li0, key procedures including Li-stripping-related issues (e.g., mass transport, ion/electron transfer), solid electrolyte interphase (SEI) evolution, and effective dead Li0 exposure should be concurrently considered. The answer may be obtained through in-depth mechanistic studies using advanced characterization techniques. Additionally, insights into dead Li0 reactivation can be gained from existing methods (e.g., high cutoff voltage, lower current density) and from detecting environmental changes around the reactivated dead Li0 to identify favorable conditions. Such recognition of dead Li0 reactivation promises LMBs with prolonged lifespan, which can further be extended to other battery systems.