Stabilizing the Interface between Sodium Metal Anode and Sulfide-Based Solid-State Electrolyte with an Electron-Blocking Interlayer

Sulfide-based Na-ion conductors are promising electrolytes for all-solid-state sodium batteries (ASSSBs) because of high ionic conductivity and favorable formability. However, no effective strategy has been reported for long-duration Na cycling with sulfide-based electrolytes because of interfacial challenges. Here we demonstrate that a cellulose–poly(ethylene oxide) (CPEO) interlayer can stabilize the interface between sulfide electrolyte (Na3SbS4) and Na by shutting off the electron pathway of the electrolyte decomposition reaction. As a result, we achieved stable Na plating/stripping for 800 cycles at 0.1 mA cm–2 in all-solid-state devices at 60 °C.