Challenges and opportunities of practical sulfide-based all-solid-state batteries

All-solid-state batteries (ASSBs) are regarded as the most promising next-generation batteries for electric vehicles in virtue of their potential advantages of enhanced safety, high energy density and power capability. Among the ASSBs based on various solid electrolytes (SEs), sulfide-based ASSBs have attracted increasing attention due to the high ionic conductivity of sulfide SEs which is comparable to that of liquid electrolytes. Extensive efforts from academia and industry have been made to develop sulfide-based ASSBs, and several significant progress has been achieved in recent years. However, successful fabrication of high-performance sulfide-based ASSBs has been rarely reported, and the practical application of sulfide-based ASSBs still faces a variety of challenges. Herein, following a bottom-up approach, we present a comprehensive review of the critical issues of practical sulfide-based ASSBs from the material, interface, composite electrode to cell levels. The existing challenges, recent advances, and future research directions of sulfide-based ASSBs at multiple levels are discussed. Finally, several fabrication processes for scaling up sulfide-based ASSBs and existing pilot/mass production schedules of sulfide-based ASSBs of the leading companies are also introduced. Facing the existing challenges and future opportunities, we highly encourage joint efforts and cooperation across the battery community to promote the practical application of sulfide-based ASSBs.