NaOH as an Aqueous Electrolyte to Improve the Performance of Electric Double-Layer Capacitors—A Molecular Dynamics Study

Aqueous electrolytes are widely used in supercapacitors (SCs) because of their high stability, wide voltage window, and safety features at elevated temperatures. Among alkaline electrolytes, KOH is most commonly used, and other electrolytes are less addressed. In this work, we meticulously investigated the diffusion behavior of Na+ and K+ in aqueous electrolytes going through hierarchical porous activated carbon materials by employing molecular dynamic simulations. Our results show that the diffusion coefficient of NaOH is much larger than that of KOH under different concentrations, electric fields, and temperatures. We attributed this to the radical of ions going through the mesopores with layered structures. The advantage of high diffusion and low cost of NaOH electrolyte suggests that it could be a potential candidate to improve the performance of SCs.