NiS nanosheets with novel structure anchored on coal-based carbon fibers prepared by electrospinning for flexible supercapacitors†
Elm seed-like nickel sulfide nanosheets grown on the surface of coal-based carbon fibers are reasonably constructed and prepared by a multistep transformation approach. The silica/coal-based carbon fibers are obtained via electrospinning a water/N,N-dimethylformamide two-phase solution of oxidized coal, polyvinyl alcohol and tetraethyl orthosilicate, followed by carbonization. The elm seed-like nickel silicate nanosheets formed by many small nickel silicate nanosheets are deposited on the surface of the coal-based carbon fibers, and then transformed into nickel sulfide with a similar morphology by chemical conversion. Benefiting from the large specific surface area and unique novel structure of the obtained sample, the obtained binder-free electrode exhibits a high specific capacitance of 635.1 F g−1 at 1 A g−1 and delivers a good capacitance retention of 96.4% over 5000 cycles, which are much higher than those of the reference sample without tetraethyl orthosilicate (298.5 F g−1 and 87.7%, respectively). This design idea offers a new strategy for the synthesis of elm seed-like nickel sulfide nanosheet/coal-based carbon fiber composites as flexible electrode materials.