Reconstruction of Solid Electrolyte Interphase with SrI2 Reactivates Dead Li for Durable Anode‐Free Li‐Metal Batteries

Abstract Without excess Li, anode‐free Li‐metal batteries (AFLMBs) have been proposed as the most likely solution to realizing highly‐safe and cost‐effective Li‐metal batteries. Nevertheless, short cyclic life puzzles conventional AFLMBs due to anodic dead Li accumulation with a local current concentration induced by irreversible electrolyte depletion, insufficient active Li reservoir and slow Li + transfer at the solid electrolyte interphase (SEI). Herein, SrI 2 is introduced into carbon paper (CP) current collector to effectively suppress dead Li through synergistic mechanisms including reversible I − /I 3 − redox reaction to reactivate dead Li, dielectric SEI surface with SrF 2 and LiF to prevent electrolyte decomposition and highly ionic conductive (3.488 mS cm −1 ) inner layer of SEI with abundant LiI to enable efficient Li + transfer inside. With the SrI 2 ‐modified current collector, the NCM532/CP cell delivers unprecedented cyclic performances with a capacity of 129.2 mAh g −1 after 200 cycles.