Revitalizing Lithium Metal Batteries: Strategies for Tackling Dead Lithium Formation and Reactivation.

Lithium (Li) metal batteries (LMBs) are among the most promising candidates for future battery technology due to their high theoretical capacity and energy density. However, the formation of dendritic Li, characterized by needle-like structures, poses serious safety issues. To address this, numerous methods are developed to prevent Li dendrite formation. Another significant challenge in LMBs is the formation of inactive Li, known as dead Li, which significantly impacts their Coulombic efficiency and overall performance. This review explores the issues surrounding dead Li in LMBs, specifically focusing on electrically isolated Li metal and the repeatedly generated solid electrolyte interphase (SEI). Advanced techniques for characterizing inactive Li are discussed, alongside various strategies designed to activate or suppress dead Li, thus restoring battery capacity. The review summarizes recent advancements in research related to the activation, reuse, and prevention of dead Li, offering valuable insights for enhancing the efficiency and safety of LMBs. This comprehensive overview provides fundamental guidance for the practical application of Li metal anodes and similar metal batteries.