Superior All‐Solid‐State Batteries Enabled by a Gas‐Phase‐Synthesized Sulfide Electrolyte with Ultrahigh Moisture Stability and Ionic Conductivity

Sulfide solid electrolytes (SEs) are recognized as one of the most promising candidates for all‐solid‐state batteries (ASSBs), due to their superior ionic conductivity and remarkable ductility. However, poor air stability, complex synthesis process, low yield, and high production cost obstruct the large‐scale application of sulfide SEs. Herein, a one‐step gas‐phase synthesis method for sulfide SEs with oxide raw materials in ambient air, completely getting rid of the glovebox and thus making large‐scale production possible, is reported. By adjusting substituted elements and concentrations, the ionic conductivity of Li4‐xSn1‐xMxS4 can reach 2.45 mS cm−1, which represents the highest value among all reported moist‐air‐stable and recoverable lithium‐ion sulfide SEs reported. Furthermore, ASSBs with air/water‐exposed and moderate‐temperature‐treated Li3.875Sn0.875As0.125S4 even maintains superior performances with the highest reversible capacity (188.4 mAh g−1) and the longest cycle life (210 cycles), which also breaks the record. Therefore, it may become one of the most critical breakthroughs during the development of sulfide ASSBs toward its practical application and commercialization. A novel one‐step gas‐phase method is introduced to synthesize sulfide electrolyte from oxides in ambient air, making the synthesis process air‐stable and glovebox‐free. The as‐synthesized Li3.875Sn0.875As0.125S4 possesses the highest ionic conductivity among all reported moist‐air‐stable sulfides, promoting potential mass production of all‐solid‐state batteries with high reversible capacity (188.4 mAh g−1) and long cycle life (210 cycles).