Ultrafast Synthesis of I‐Rich Lithium Argyrodite Glass–Ceramic Electrolyte with High Ionic Conductivity

Abstract Lithium argyrodites are one of the most promising sulfide electrolytes due to their high ionic conductivity and ductile feature. Among them, Li₆PS₅I (LPSI) exhibits better stability against Li metal but a rather low ionic conductivity (only ≈10⁻⁶ S cm⁻¹) because of the absence of S²⁻/I⁻ disorder. Herein, argyrodite Li_6−xPS_5−xI_1+x glass–ceramic electrolytes with high iodine content are synthesized using ultimate‐energy mechanical alloying method. S²⁻/I⁻ disorder is successfully introduced into the system by doping LiI during this one‐pot process. Determined by ⁶Li magic angle spinning nuclear magnetic resonance and ab initio molecular dynamics simulations, the introduction of iodine promotes Li⁺ inter‐cage jumps, leading to an enhanced long‐range Li⁺ conducting. The Li_5.6PS_4.6I_1.4 glass–ceramic electrolyte (LPSI_1.4‐gc) possesses high ionic conductivity (2.04 mS cm⁻¹) and excellent stability against Li metal. The Li symmetric cell with the LPSI_1.4‐gc electrolyte demonstrates ultralong cycling stability over 3200 h at 0.2 mA cm⁻². LiCoO₂/Li₆PS₅Cl/Li all‐solid‐state battery applying LPSI_1.4‐gc as the anode interlayer also presents prominent cycling and rate performance. This work provides a novel type of electrolyte with high ionic conductivity and stability against Li metal.