Regulating Solvating Configuration to Achieve Long-Cycle-Life in Sodium-SPAN Batteries

Room-temperature sodium-sulfur polyacrylonitrile (SPAN) batteries are regarded as promising energy storage technology due to their high energy density, low cost, and high safety. However, dendrite growth in sodium anodes and dissolution shuttling effects in sulfur cathodes hinder their practical application. Here, we designed and achieved a solvation structure dominated by tridentate coordination by regulating the solvation configuration between sodium ions and diglyme through solvation strategies. The results indicate that the tridentate solvation structure not only reduces the dissolution shuttling of sodium polysulfide but also promotes the formation of a stable double-layer inorganic electrolyte interface on the surface of the Na anode. The Na-SPAN batteries achieved a high capacity retention of 97.46% after 1138 cycles and a calendar life exceeding 1 year at room temperature. Moreover, assembled Na-SPAN batteries maintained 94.7% of their initial capacity after 445 cycles at 50°C. This work provides a well-designed electrolyte principle for constructing a low-cost, long-cycle-life room-temperature Na-SPAN battery.