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

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Lithium argyrodites are one of the most promising sulfide electrolytes due to their high ionic conductivity and ductile feature. Among them, Li₆ PS₅ I (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 Li₆₋ x PS₅₋ x I₁₊ 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 ⁶ Li 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 Li5.6 PS4.6 I1.4 glass-ceramic electrolyte (LPSI1.4 -gc) possesses high ionic conductivity (2.04 mS cm⁻¹ ) and excellent stability against Li metal. The Li symmetric cell with the LPSI1.4 -gc electrolyte demonstrates ultralong cycling stability over 3200 h at 0.2 mA cm⁻² . LiCoO₂ /Li₆ PS₅ Cl/Li all-solid-state battery applying LPSI1.4 -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.