Dual Play of Chitin-Derived N-Doped Carbon Nanosheets Enabling High-Performance Na-SeS2 Half/Full Cells

Room-temperature Na-S batteries hold great promise for developing next-generation battery system with the advantages of abundant resource, high energy density, and long lifetime. However, limited by sluggish kinetics, Na-S batteries frequently suffer from low utilization of active materials, rapid capacity decay during cycling and poor rate capability. Herein, we propose an advanced cathode with SeS2 tightly impregnated in chitin-derived rich nitrogen carbon nanosheets (termed as CCN/SeS2). The CCN/SeS2 exhibits superb rate capability (422 mAh g(-1) at 5 A g(-1)) and long cycle stability (566 mAh g(-1) after 470 cycles with a capacity decay rate of 0.056 % per cycle). High content and high loading cathodes are also fabricated to meet the requirement of practical application. The results of electrochemical tests and characterization demonstrate that CCN/SeS2 has preponderance in lowering overpotential and reaction resistances, prompting the diffusion of sodium ions and achieving the uniform deposition of discharge products. For the first time, a full cell based on all-chitin materials (CCN/SeS2 cathode and CCN anode) is assembled, which exhibits favorable cycling performance over 100 cycles. The as-obtained cell using a green and low-cost carbon and SeS2 inheriting the advantages of Se and S may pave a new way to energy storage.