Anode SHIELD: A Surface Hybrid Interlayer for High‐Capacity Anodes Toward Safe and Stable Lithium‐Ion Batteries

Abstract Implementation of thick electrodes is a promising strategy for enhancing the energy density of Li‐ion batteries (LIBs). However, high tortuosity and sluggish Li‐ion kinetics in thick anodes lead to depth‐dependent reaction inhomogeneity, resulting in Li metal plating, electrode degradation, and poor electrochemical performance. This study applies a surface hybrid interlayer for electrode stabilization and locking dendrite (SHIELD) to the anode surface to address these challenges. SHIELD immobilizes PF 6 − anions in Li salts on its surface, facilitating efficient Li‐ion transport within the electrode and inducing a stable solid electrolyte interphase (SEI) layer with excellent ionic conductivity. These effects synergistically enhance Li‐ion kinetics, thereby suppressing reaction inhomogeneity. Additionally, SHIELD improves the structural stability of the anode by providing mechanical reinforcement and guiding homogeneous reactions. Moreover, SHIELD inhibits dendritic Li growth on the electrode surface even under Li plating conditions, owing to the increased Li‐ion transference number. Consequently, the thick Si/graphite anode with SHIELD (anode‐SHIELD) exhibits superior cycling performance in LIBs, maintaining its structural integrity. Furthermore, the anode‐SHIELD demonstrates significantly improved cycling stability during repeated overcharge/discharge tests (at 120% of the electrode capacity), effectively mitigating dendritic Li growth. This study offers new insights for developing long‐term, reversible, high‐loading anodes for next‐generation LIBs.