Nitrogen‐Doped Graphene Nanosheets/S Composites as Cathode in Room‐Temperature Sodium‐Sulfur Batteries

Room-temperature sodium-sulfur (RT Na−S) batteries have gained increasing attention from energy storage community in recent years. In this work, homogeneous nitrogen-doped graphene nanosheets/sulfur (NGNS/S) nanocomposites, synthesized using chemical reaction-deposition method and low temperature heat treatment, were studied as active cathode materials for RT Na−S batteries. Different loading composites with 86%, 65%, 45% and 25% gamma-S8 have been electrochemically evaluated, respectively, and compared with two control electrodes of NGNS and S. It was found that the NGNS/S composite with 25% S loading exhibited the best electrochemical performance with specific capacities of 212 and 136 mAh g−1 in the 1st and 10th cycles, respectively. The enhanced electrochemical performance of NGNS/S nanocomposite is mainly attributed to the improved kinetics due to the NGNS conductive network and easier intercalation of Na+ into expanded NGNS layers due to the addition of S within the graphene layers. In addition, the composite with 25% S loading shows higher surface area and complete reaction with product of Na2S, which likely contributes to the improved energy capacity.