Evaluation of Electrochemical Stability of Graphite Current Collector for Electric Double Layer Capacitor Based on Acid Electrolyte

Owing to its low cost, easy fabrication process, and good ionic properties, aqueous supercapacitors are under strong consideration as next-generation energy storage devices. However, the limitation of the current collector is its poor electrochemical stability, leading to low energy storage performance. Therefore, a reasonable design of the current collector and the acidic electrolyte is a necessary, as well as interfacial engineering to enhance the electrochemical performance. In the present study, graphite foil, with excellent electrochemical stability and good electrical properties, is suggested as a current collector of aqueous supercapacitors. This strategy results in excellent electrochemical performance, including a high specific capacitance of 215 F g⁻¹at a current density of 0.1 A g⁻¹, a superior high-rate performance (104 F g⁻¹at a current density of 20.0 A g⁻¹), and a remarkable cycling stability of 98 % at a current density of 10.0 A g⁻¹after 9,000 cycles. The superior energy storage performance is mainly ascribed to the improved ionic diffusion ability during cycling.