Integrated Self-Supporting Na2Se/Na2S@CNF Cathode for Long-Cycle Room-Temperature Sodium–Sulfur Batteries

Room-temperature sodium–sulfur batteries have broad prospects, but Na2S cathodes suffer from poor electrochemical performance and insufficient air stability. By introducing Na2SeO3 as a precursor, a Na2Se/Na2S@CNF composite cathode is prepared. TEM reveals continuous heterojunction interfaces. Electrochemical performance is significantly enhanced: the initial charge capacity reaches 664 mAh g−1, and the reversible capacities at 0.2, 0.5, 1, 2, 3, and 5 C rates are 774, 722, 636, 574, 494, and 396 mAh g−1 respectively, with a reversible capacity of 600 mAh g−1 after 300 cycles at 1 C.