High Performance Room Temperature Sodium–Sulfur Battery by Eutectic Acceleration in Tellurium-Doped Sulfurized Polyacrylonitrile

Room-temperature sodium-sulfur batteries suffer from slow reaction kinetics and polysulfide dissolution, resulting in poor performance. Sulfurized polyacrylonitrile is a unique sulfur cathode which is suggested to involve only S3-4 and shows high specific capacity. Herein, the designed Te0.04S0.96@pPAN with 4 mol% Te used as eutectic accelerator exhibits significantly enhanced reaction kinetics and excellent sulfur utilization, leading to a high performance RT Na-S battery. Te0.04S0.96@pPAN delivers capacities of 1236 and 629 mA h g-1, 1111 and 601 mA h g-1 at 0.1 and 6 A g-1 in carbonate and ether electrolytes, respectively. Furthermore, UV-vis spectra and shuttle current test reveal diminished sodium polysulfides in ether electrolyte, attributed to the fast kinetics enabled by Te-doping. More significantly, the spectra technique and electrochemical analysis demonstrate a two-step reaction pathway in which Na2S3 and Na2S are the main intermediate and final discharge-product, respectively. This method pro...