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, 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 S^2- /I^- disorder. Herein, argyrodite Li_6- _x PS_5- _x I₁₊ _x glass-ceramic electrolytes with high iodine content are synthesized using ultimate-energy mechanical alloying method. S^2- /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 Li_5.6 PS_4.6 I_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 /Li₆ PS₅ Cl/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.