Molecular Halofluorocarbon Regulation of Li Metal/Li ₆ PS ₅ Cl Interfaces Through a C ₆ F ₁₃ I‐Derived LiF/LiI‐Rich Interphase

Sulfide solid electrolytes are highly attractive for all‐solid‐state batteries because of their high ionic conductivity and favorable processability, yet their practical integration with Li metal anodes remains severely hindered by interfacial instability. Here, we report a simple surface‐regulation strategy by coating Li 6 PS 5 Cl (LPSC) with C 6 F 13 I (CFI) to construct a Li‐compatible interfacial chemistry. X‐ray photoelectron spectroscopy reveals the emergence of C–F and LiF species. The optimized LPSC@CFI5 maintains an ionic conductivity of 1.22 mS cm −1 while markedly increasing the critical current density from 0.9 to 1.5 mA cm −2 . Moreover, the Li|LPSC@CFI5|Li symmetric cell exhibits prolonged and low polarized stripping/plating stability for 1000 h at 0.1 mA cm −2 . When extended to LCO/LPSC/Li full cells, the CFI‐modified electrolyte enables more stable charge/discharge behavior and improved cycling reversibility at 0.1 C. Our work offers a simple molecular strategy to improve the interfacial compatibility of sulfide solid electrolytes with Li metal, thereby advancing the practical development of sulfide‐based all‐solid‐state batteries.