Rational design of mesoporous NiWO4 / Co3O4/ g-C3N4 based heterostructure for high performance asymmetric supercapacitors

Abstract

Herein we have designed a nickel-based tungsten oxide as a cathode material for hybrid supercapacitor owing to its better theoretical capacitance values. However, the material lacks good conducting behaviour and rate capability which affect its extensive utilisation as electrode material. In order to overcome the defects heterostructure composite was designed to enhance its electrochemical behaviour. The prepared materials were characterised with several physiochemical and electrochemical techniques. The ternary nanocomposite has portrayed cube like morphology with mesoporous nature. In specific, the ternary composite in three electrode cell have delivered a high specific capacitance of 819 F/g at 1 A/g when compared to other materials and retained a initial capacitance of 91 % after 5000 charge discharge cycles. Then an asymmetric hybrid supercapacitor with NiWO₄/Co₃O₄/g-C₃N₄ as positive electrode and rGO as negative electrode in 3 M PVA-KOH electrolyte using Swagelok cell was assembled. The fabricated device exhibited a specific capacitance of about 113 F/g at 1 A/g in the potential of 1.4V with a specific energy of 35 Wh/kg at an specific power of 1500 W/kg. Further the device exhibited a better cycle life of 93 % even after 10000 cycles. Thus, the transition metal tungstate based heterostructure could be employed as a potential electrode material for efficient supercapacitors.