Recent advances in quantifying the inactive lithium and failure mechanism of Li anodes in rechargeable lithium metal batteries

Lithium metal is considered as the ultimate anode material for the next generation of high-energy density batteries. However, non-uniform lithium dendrite growth, serious electrolyte consumption, and significant volume changes during lithium deposition/stripping processes lead to sustained accumulation of inactive lithium and poor cycling reversibility. Quantifying the formation and evolution of inactive lithium under different conditions and fully evaluating the complex failure modes are the key issues in this challenging field. This article comprehensively reviews recent research progresses on the quantification of formation and evolution of inactive lithium detected by different quantitative techniques in rechargeable lithium metal batteries. The key research challenges such as failure mechanism, modification strategies and operando characterization of lithium metal anodes are systematically summarized and prospected. This review provides a new angle of view to understand failure mechanism of lithium metal anodes and inspiration and guidance for the future development of rechargeable lithium metal batteries.