High-performance all-solid-state electrolyte for sodium batteries enabled by the interaction between the anion in salt and NaSbS.

All-solid-state sodium batteries with poly(ethylene oxide) (PEO)-based electrolytes have shown great promise for large-scale energy storage applications. However, the reported PEO-based electrolytes still suffer from a low Na transference number and poor ionic conductivity, which mainly result from the simultaneous migration of Na and anions, the high crystallinity of PEO, and the low concentration of free Na. Here, we report a high-performance PEO-based all-solid-state electrolyte for sodium batteries by introducing NaSbS to interact with the TFSI anion in the salt and decrease the crystallinity of PEO. The optimal PEO/NaTFSI/NaSbS electrolyte exhibits a remarkably enhanced Na transference number (0.49) and a high ionic conductivity of 1.33 × 10 S cm at 45 °C. Moreover, we found that the electrolyte can largely alleviate Na depletion near the electrode surface in symmetric cells and, thus, contributes to stable and dendrite-free Na plating/stripping for 500 h. Furthermore, all-solid-state Na batteries with a 3,4,9,10-perylenetetracarboxylic dianhydride cathode exhibit a high capacity retention of 84% after 200 cycles and superior rate performance (up to 10C). Our work develops an effective way to realize a high-performance all-solid-state electrolyte for sodium batteries.