Li1.5Al0.5Ge1.5(PO4)3 Ceramic Based Lithium‐Sulfur Batteries with High Cycling Stability Enabled by a Dual Confinement Effect for Polysulfides

Abstract Aimed at tackling the shuttle effect in lithium‐sulfur (Li−S) batteries, a Li 1.5 Al 0.5 Ge 1.5 (PO 4 ) 3 (LAGP) ceramic is adopted to block the migration of polysulfides. However, the LAGP‐based Li−S battery with liquid electrolyte wetting the interfaces still suffers from rapid capacity decay, as polysulfides tend to dissolve into liquid electrolyte and get firmly adsorbed by LAGP. In this work, a dual confinement effect for polysulfides is put forward, enabled by the LAGP ceramic and solvent‐in‐salt (SIS), wherein the SIS can greatly suppress the dissolution of polysulfides. Owing to the synergistic effect of SIS and LAGP, the semi‐solid‐state Li−S batteries show superior capacity retention and long cycling life. In particular, at a current density of 0.2 C, the Li−S battery with SIS‐modified LAGP ceramic electrolyte delivers a high initial reversible capacity of 1251.7 mAh g −1 and long cycle life of over 250 cycles with a decay rate of only 0.07 % per cycle.