In Situ Construction of Inorganic‐Rich Solid Electrolyte Interphase via Selective Anode‐Electrolyte Interactions Enabling Stable Lithium Metal Batteries

Abstract Lithium metal batteries (LMBs) are considered promising candidates for high‐energy‐density energy storage. However, the practical application of lithium (Li) metal anodes is highly constrained by the limited ionic conductivity, localized electronic leakage, and poor mechanical stability of their solid electrolyte interphase (SEI). Herein, a Li‐Sr‐N (LSN) anode is fabricated by mechanically rolling Sr ₃ N ₂ powder with Li foil, forming a LiSrN/Li ₃ N/Li ₂₃ Sr ₆ /Li heterointerface on the foil surface. As demonstrated by both experimental characterizations and theoretical calculations, the as‐constructed heterointerface can actively interact with the fluoroethylene carbonate (FEC) molecules in the electrolyte, leading to the in situ formation of a uniform Li ₃ N/LiF/SrF ₂ ‐hybrid SEI with high ionic conductivity and electronic insulation. With this design, the LSN||LSN symmetric cell exhibits stable cycling performance over 1000 cycles at 1 mA cm ⁻² and 1 mAh cm ⁻² in carbonate‐based electrolytes. The NCM95||LSN coin‐type full cell with an ultrahigh loading cathode (≈18 mg cm ⁻² ) achieves 89.6% capacity retention over 100 cycles at 1.0 C (214 mA g ⁻¹ ). Furthermore, the NCM95||LSN pouch cell with a low N/P ratio (≈1.7) and lean electrolyte (≈1.37 g Ah ⁻¹ ) delivers a high energy density of ≈440.8 Wh kg ⁻¹ and maintains 91.1% capacity retention after 100 cycles at 0.2 C.