Design Unique Air‐Stable and Li–Metal Compatible Sulfide Electrolyte via Exploration of Anion Functional Units for All‐Solid‐State Lithium–Metal Batteries

The marriage of solid-state sulfide electrolytes (SSSEs) with Li-anode and oxide-based cathodes can multiply the energy density of all-solid-state Lithium–metal batteries (ASSLMBs). However, hydrolysis in the air, reduction at the Li/SSSE interface, and growth of Li-dendrites inside SSSEs collectively block the route of sulfide-based ASSLMBs. Herein, a novel Li2.96P0.98S3.92O0.06-Li3N glass–ceramic electrolyte (GCE) is developed, wherein O and N substitution produce POS33– and Li3N unique functional units enable superior σLi+ 1.58 mS cm–1 at RT. Notably, POS33– units in Li2.96P0.98S3.92O0.06-Li3N excellently prevent the structural degradation against moisture @45–50%. The critical current density of Li2.96P0.98S3.92O0.06–Li3N reaches 1 mA cm–2/1 mAh cm–2 @ RT. Moreover, Li//Li cells realize unprecedented Li-plating/stripping >1000 h at 0.3 mA cm–2/0.3 mAh cm–2 and 0.5 mA cm–2/0.5 mAh cm–2 at RT. ToF-SIMS and depth-X-ray photoelectron spectroscopy (XPS) confirm the formation of Pre-solid-electrolyte interphase (SEI) enriched with thermodynamically stable Li2O and Li3N species at Li/Li2.96P0.98S3.92O0.06–Li3N interface, suppressing the interfacial reactions and growth of Li-dendrites inside Li2.96P0.98S3.92O0.06–Li3N. Furthermore, LiNbO3@NCA/Li2.96P0.98S3.92O0.06–Li3N/Li cells deliver a remarkable initial discharge capacity of 177.3, 177.6, and 177.8 mAh g–1 with 7.50, 16.50, and 21.50 mg cm–2 of NCA loading. Thus, the novel Li2.96P0.98S3.92O0.06–Li3N GCE addresses all key challenging issues and has tremendous potential to be used in sulfide-based high-energy ASSLMBs.