Synthesis of NiCo2S4 nanosheets coated on biomass activated carbon for high-performance asymmetric supercapacitors

Owing to its intrinsic characteristic, biomass activated carbon (AC) extracted from bagasse demonstrates high specific surface area and porous structure, which is widely regarded as a promising substrate to design AC@transition metal compound electrode material. Herein, NiCo2S4 nanosheets uniformly grown on bagasse activated carbon (BAC@NiCo2S4) is successfully prepared as composite electrode material for supercapacitors. Owing to the presence of porous BAC substrate with a large specific surface area of 1712.49 m2 g-1, the as-prepared BAC@NiCo2S4 composite demonstrates hierarchical structure with a considerable specific surface area of 208.58 m2 g-1 and good micro-mesoporous characteristic, thereby improving electrical performances with an impressive specific capacity of 2264 F g-1 at 1 A g-1, and a good rate capability of 77.9 % retention from 1 to 20 A g-1. Additionally, the as-assembled BAC@NiCo2S4//BAC asymmetric supercapacitor provides a high energy density of 64.9 W h kg-1 at 800.1 W kg-1, and maintains 32.4 W h kg-1 when the power density is up to 8000.2 W kg-1. The above results suggest that the BAC@NiCo2S4 composite is a competitive electrode material in the field of energy storage.