NiWO4/Ni/Carbon Composite Fibres for Supercapacitors with Excellent Cycling Performance

•A novel NiWO4/Ni/carbon fibre electrode was fabricated by combining electrospin with spray.•Specific capacitance was sharply increased owing to Ni oxidation into Ni2+.•The energy density was 41.3 Wh kg−1 at 193.8 Wh kg−1.•WO42− was attributed to the conversion of Ni oxidated intoNi2+.

A novel NiWO4/Ni/carbon fibre composite was fabricated by the combination of electrospining with spray deposition and subsequent carbonization. It was revealed that NiWO4 and Ni were uniformly dispersed outside and inside the carbon fibres, respectively. Used as supercapacitor electrode, the as-prepared fibre composite shows excellent capacity and cyclability. Galvanostatic discharge/charge test showed that the specific capacitance sharply increased from 151.1 to 792.2 F g−1 at 5 A g−1 after 1500 cycles, which was attributed to the oxidation of metallic Ni into ionic Ni2+ forming more reactive sites. An electrochemical asymmetric supercapacitor was assembled using the composite fibres and porous carbon nanofibers, of which the energy density increased from 32.5 to 41.3 Wh kg−1 at 193.8 W kg−1. The results clearly showed that NiWO4/Ni/carbon fibre material is of potential in energy harvesting and storage.

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