Achieving high-performance room-temperature sodium−sulfur batteries with S@interconnected mesoporous carbon hollow nanospheres

Despite the high theoretical capacity of the sodium-sulfur battery, its application is seriously restrained by the challenges due to its low sulfur electroactivity and accelerated shuttle effect, which lead to low accessible capacity and fast decay. Herein, an elaborate carbon framework, interconnected mesoporous hollow carbon nanospheres, is reported as an effective sulfur host to achieve excellent electrochemical performance. Based on in-situ synchrotron X-ray diffraction, the mechanism of the room temperature Na/S battery is proposed to be reversible reactions between S8 and Na2S4, corresponding to a theoretical capacity of 418 mAh g-1. The cell is capable of achieving high capacity retention of ~ 88.8% over 200 cycles, and superior rate capability with reversible capacity of ~ 390 and 127 mAh g- 1 at 0.1 and 5 A g-1, respectively.