β-Ni(OH)2 / WC for high-energy aqueous hybrid supercapacitor

Abstract

This study focuses on synthesizing tungsten carbide incorporated β-Ni(OH)2 composite as a positive electrode in asymmetric supercapacitor applications. The composite was prepared for different concentrations of WC (5,10, and 15 wt.%). The bare β-Ni(OH)2 and β-Ni(OH)2/WC composites were tested in the three-electrode system using a KOH electrolyte. The characteristics performances were optimized based on the electrochemical performance of the three electrode configurations. The typical lab-scale asymmetric supercapacitor device delivered a maximum specific energy of 66.78 Wh kg−1 at ⁓0.3 A g−1 in a 2 M KOH electrolyte medium. Further, the pouch-type supercapacitor was fabricated using a PVA-KOH hydrogel electrolyte. The pouch cell delivers a specific energy of 18.69 Wh kg−1 at a specific power of 3.282 kW kg−1 at 1 A g−1. The supercapacitor also shows a capacitance retention of 76 % even after 17,000 cycles at 1.25 A g−1. Thus, it is evident that an optimum composition of the β -Ni(OH)2 / WC(5 wt.%) composite will be an effective positive electrode in an asymmetric supercapacitor for obtaining high specific energy.