Tailoring the Interface between Sulfur and Sulfide Solid Electrolyte for High-Areal-Capacity All-Solid-State Lithium–Sulfur Batteries

Fabricating high-capacity all-solid-state lithium-sulfur batteries (ASSLSBs) with long lifetimes is realistically challenging because of the poor ionic contact between the insulating element sulfur (S 8 ) and the solid electrolyte at the solid–solid interface. Herein, an inorganic Li-ion-conducting species composed of polysulfido-intermediate compounds (3Li + -PS 4+ n 3– ( n ≥ 0)) is incorporated between S 8 and the sulfide solid electrolyte (SSE) of Li 6 PS 5 Cl (LPSCl) to enhance the ionic contact of S 8 . A weakly polar solvent which is included in the mixing process but eventually removed promotes interfacial chemical reactions between S 8 and LPSCl, significantly enhancing the wettability of LPSCl toward the active material (S 8 ). This maximizes the utilization of S 8, facilitates interfacial Li-ion transport, and enhances the mechanical properties of the solid-state S cathode. As a result, a high-performance ASSLSB with a high areal capacity (5.1 mAh cm –2 ) and promising lifetime (250 cycles) at room temperature, operating at a current density of 1 mA cm –2, is successfully developed.