Solvothermal synthesis of NiWO4 nanostructure and its application as a cathode material for asymmetric supercapacitors

Abstract

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.