Partially reduced graphene oxide-based electrolyte: synthesis and electrochemical capacitance performance

The increasing demand for higher-energy-density supercapacitors driven by advancements in devices necessitates the development of alternative electrolytes with a higher specific capacity or larger voltage window. Compared with the fruitful results achieved by expanding the voltage window, there is less report on the method of using electrolytes to directly improve the capacitance performance of electrode materials, thereby increasing the energy density of the device. Herein, a new strategy has been developed to prepare electrolytes by mixing partially reduced graphene oxide (PrGO) and polypyrrole into the salt solution (NaClO₄), where the PrGO is controlled at the critical state of solid precipitation by adjusting the degree of reduction. Furthermore, density functional theory calculations are also carried out to study the relationship between the band gap of PrGO and the degree of reduction. Since the PrGO-based conductive active group is dissolved in the electrolyte, the electrolyte has the potential to increase the effective area of the solid electrode during the charging and discharging process, thus increasing the capacitance of the device. The specific area capacitance of commercial carbon cloth electrodes in this electrolyte is much higher than that in traditional salt solution electrolyte (1525 vs. 90 mF cm⁻²). In particular, the cycle performance of the device has also been greatly improved. After 10000 charge–discharge cycles, the device has reached 110.64% of the initial capacitance. Since this electrolyte has no special requirements for electrode materials, this novel electrolyte preparation strategy has broad application prospects in energy storage devices based on supercapacitor.