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 (S8) and the solid electrolyte at the solid–solid interface. Herein, an inorganic Li-ion-conducting species composed of polysulfido-intermediate compounds (3Li+-PS4+n3– (n ≥ 0)) is incorporated between S8 and the sulfide solid electrolyte (SSE) of Li6PS5Cl (LPSCl) to enhance the ionic contact of S8. A weakly polar solvent which is included in the mixing process but eventually removed promotes interfacial chemical reactions between S8 and LPSCl, significantly enhancing the wettability of LPSCl toward the active material (S8). This maximizes the utilization of S8, 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.