Electrode structural changes and their effects on capacitance performance during preparation and charge-discharge processes

Activated carbon has attracted increasing attention in commercial supercapacitors due to its high porosity and physicochemical stability. The pore structure and specific surface area of activated carbon determine its capacitance but these may change during the process of electrode preparation, and hence affecting the final capacitance performance. In this study, the structural change of activated carbon is experimentally evaluated by varying electrode preparation parameters, including pressure, added binder, and conductive agents. Then the changes of electrode structure during charge-discharge processes are further investigated, and find that electrode volume expanded during cycling, increasing the specific surface area and electrode supercapacitance. Compared to carbon black conductive additive, graphene can be more effective in reducing electrode volume expansion, leading to higher capacitance and cycle stability. Under the optimum conditions, the capacitance of activated carbon electrode containing 3% graphene increases by 17% and shows excellent cyclic stability. Overall, these findings are valuable for enhancing the performance of supercapacitors in industrial applications.