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 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 0.2mA 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.