Investigating the effect of electrolyte and its concentration dependence on WO3 nanosheet as an efficient electrode for supercapacitors: Effect of Redox Additive

Abstract

This research aimed to synthesize non-uniform nanosheet-like tungstate oxide (WO3) using a simple hydrothermal process, which would result in an effective and environment-friendly material for use in supercapacitors (SCs). The resulting materials are thoroughly examined using physio-chemical techniques. The supercapacitive properties of the WO3–Ni-Foam (NF) were examined using 1 M KOH, NaOH, and LiOH electrolytes and further, the electrochemical performance of the WO3–NF electrode was assessed by changing the concentration of KOH electrolytes from 1 to 4 M respectively. The WO3–NF electrode demonstrated the highest specific capacity (Csp) of 70 mAh/g and capacitance (Cs) of 563 F/g with a high energy density of 16 Wh/kg, and power density of 281 W/kg in 2 M KOH electrolyte respectively. Additionally, the WO3–NF electrode showed excellent Columbic efficiency of 98% and long-term capacitive retention of 88% over 5000 cycles in 2 M KOH electrolyte. Additionally, the effect of redox additive (0.01 M of potassium ferrocyanide) improves the electrochemical performance of WO3–NF; the Csp and Cs values were 137 mAh/g, 618 F/g and 100 mAh/g, 800 F/g at 5 mV/s and 5 mA/cm2, respectively. Furthermore, the WO3–NF electrode exhibits good stability retention of 94% over the 2000 cycles. The electrochemical performance of WO3 nanosheets for energy storage applications was improved by this straightforward hydrothermal method and evaluating the effect of redox additive electrolyte.