Interfacial challenges for all-solid-state batteries based on sulfide solid electrolytes

Sulfide solid electrolytes (e.g., lithium thiophosphates) have the highest room-temperature ionic conductivity (∼10−2 S cm−1) among solid Li-ion conductors so far, and thus have attracted ever-increasing attention for high energy-density and safety all-solid-state batteries (ASSBs). However, interfacial issues between sulfide electrolytes and electrodes have been the main challenges for their applications in ASSBs. The interfacial instabilities would occur due to side reactions of sulfides with electrodes, poor solid-solid contact, and lithium dendrites during charge/discharge cycling. In this review, we analyze the interfacial issues in ASSBs based on sulfide electrolytes, and in particular, discuss strategies for solving these interfacial issues and stabilize the electrode-electrolyte interfaces. Moreover, a perspective of the interfacial engineering for sulfide-based ASSBs is provided.