Freestanding carbon fiber cloth/sulfur composites for flexible room-temperature sodium-sulfur batteries

Carbon fiber cloth/sulfur (CFC/S) composites were prepared by loading sulfur in the carbon fiber cloth (CFC) that was obtained by carbonizing the renewable cotton cloth. The CFC/S composites are the excellent cathodes of room-temperature sodium- sulfur (RT Na-S) batteries due to their three-dimensional (3D) interconnected network and high electrolyte uptake of 1156%. The CFC/S composite with area sulfur loading of 2 mg cm(-2) displays an initial discharge capacity of 390 mA h g(-1) at 0.1 C ( 1 C=1675 mA g(-1)) and a capacity of 120 mA h g(-1) after 300 cycles with tetra ethylene glycol dimethyl ether liquid electrolyte. Furthermore, since the freestanding CFC/S composites exhibit good flexibility and conductivity, they can serve as the cathodes of flexible RT Na-S batteries. As a proof of concept, the soft-packaged RT Na-S batteries were fabricated. The capacity of soft-packaged RT Na-S batteries can remain stable when the batteries are bent.