Balance Internal and Surficial Structures of Electrochemically Exfoliated Graphene for Optimal Capacitance Performance

Electrochemical exfoliation of graphite is a cost-effective and eco-friendly method for producing graphene, which is regarded as a promising electrode material for supercapacitor, and the electrolyte may affect the product structure and capacitance properties remarkably. In this work, we examine the effects of anions in the electrolyte on the internal and surficial structures of the synthesized graphene. SO₄^2– anions help produce graphene with the highest specific surface area and a moderate amount of oxygen groups, leading to optimal double-layer capacitance and pseudocapacitance. When used in a symmetric supercapacitor, it achieves an energy density of 20.47 μWh cm^–2 at a power density of 0.25 mW cm^–2. In contrast, ClO₄^– and CO₃^2– are less effective in controlling the graphene thickness and oxygen species. This research provides insights into optimizing electrochemical exfoliation and enhancing the capacitance performance of graphene-based supercapacitors.