High-performance all-solid-state electrolyte for sodium batteries enabled by the interaction between the anion in salt and Na(3)SbS(4)

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 Na(3)SbS(4) to interact with the TFSI(−) anion in the salt and decrease the crystallinity of PEO. The optimal PEO/NaTFSI/Na(3)SbS(4) electrolyte exhibits a remarkably enhanced Na(+) transference number (0.49) and a high ionic conductivity of 1.33 × 10(−4) S cm(−1) 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.