Solvothermal synthesis of NiWO4 nanostructure and its application as a cathode material for asymmetric supercapacitors†
This study proposes a facile solvothermal synthesis of nickel tungstate (NiWO4) nanowires for application as a novel cathode material for supercapacitors. The structure, morphology, surface area and pore distribution were characterized and their capacitive performances were investigated. The results showed that the NiWO4 nanowires synthesized in ethylene glycol solvent could offer a high specific capacitance of 1190 F g−1 at a current density of 0.5 A g−1 and a capacitance retaining ratio of 61.5% within 0.5–10 A g−1. When used as a cathodic electrode of an asymmetric supercapacitor (ASC), the NiWO4 nanowire based device can be cycled reversibly in a high-voltage region of 0–1.7 V with a high specific capacitance of 160 F g−1 at 0.5 A g−1, which therefore contributed to an energy density of 64.2 W h kg−1 at a power density of 425 W kg−1. Moreover, 92.8% of its initial specific capacitance can be maintained after 5000 consecutive cycles (5 A g−1). These excellent capacitive properties make NiWO4 a credible electrode material for high-performance supercapacitors.