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

Abstract 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 Li 2.96 P 0.98 S 3.92 O 0.06 ‐Li 3 N glass–ceramic electrolyte (GCE) is developed, wherein O and N substitution produce POS 3 3– and Li 3 N unique functional units enable superior σ Li+ 1.58 mS cm –1 at RT. Notably, POS 3 3– units in Li 2.96 P 0.98 S 3.92 O 0.06 ‐Li 3 N excellently prevent the structural degradation against moisture @45–50%. The critical current density of Li 2.96 P 0.98 S 3.92 O 0.06 –Li 3 N 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 Li 2 O and Li 3 N species at Li/Li 2.96 P 0.98 S 3.92 O 0.06 –Li 3 N interface, suppressing the interfacial reactions and growth of Li‐dendrites inside Li 2.96 P 0.98 S 3.92 O 0.06 –Li 3 N. Furthermore, LiNbO 3 @NCA/Li 2.96 P 0.98 S 3.92 O 0.06 –Li 3 N/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 Li 2.96 P 0.98 S 3.92 O 0.06 –Li 3 N GCE addresses all key challenging issues and has tremendous potential to be used in sulfide‐based high‐energy ASSLMBs.