Ni0.85Co0.15WO4 nanosheet electrodes for supercapacitors with excellent electrical conductivity and capacitive performance.

Monoclinic wolframite Ni 1- x Co x WO 4 ( x  = 0 and 0.15) nanosheets are synthesized successfully through chemical co-precipitation. The specific surface area increases appreciably with reduced pore radius when Co 2+ ions are incorporated into the NiWO 4 lattice. In comparison with NiWO 4 , the band gap of Ni 0 .85 Co 0.15 WO 4 reduces with the electrical conductivity increased threefold. The electrochemical properties and the device performance of supercapacitors with Ni 1- x Co x WO 4 as electrodes are characterized via the potentiostatic and galvanostatic cycle measurements, and electrochemical impedance spectroscopy (EIS). The Ni 0.85 Co 0.15 WO 4 electrode exhibits an obvious increase in specific capacitance, six-fold higher than that of NiWO 4 electrode at a current density of 0.5 A g −1 . Ni 0.85 Co 0.15 WO 4 electrode also shows excellent rate performance with ~78% capacitive retention while the current density is enhanced fivefold. The possible mechanism for the improved electrical conductivity and capacitive performance due to the incorporation of Co 2+ to NiWO 4 lattice has been discussed. [ABSTRACT FROM AUTHOR]