Trailblazing Next Generation Sodium Battery Chemistry through Tunable Sodium Phosphorothioates

Next-generation battery chemistry based on earth-abundant elements of sodium and sulfur can deliver a high theoretical specific energy of 1274 Wh kg -1 , making low cost battery technologies possible. Nevertheless, the formation of unanchored soluble intermediate sulfur species and the precipitation of low electronically/ionically conductive solids impede the realization of such systems. Herein, by introducing another naturally plentiful element of phosphorus, we invented a new series of sodium phosphorothioates by taking advantage of the chemical affinity among these three elements, which solves the abovementioned challenges. These new materials not only serve as a high capacity cathode but also function as a stabilization reagent for sodium anode, contributing to a novel battery chemistry that delivers high electrochemical potentials and capacity. As a proof of concept, we demonstrate a high-performance sodium battery, showing an initial capacity delivery of 440 mAh g -1 along with a cyclic retention of 80% for over 400 cycles. The superiority of this new battery chemistry is fundamentally investigated by both experimental characterizations and theoretical calculations. This study can lay the groundwork in designing a low cost, high performance sodium battery chemistry that potentially meets the grid-scale energy storage requirements beyond the current lithium ion technologies. Figure 1