Molecular Dynamics Simulation of the Effect of Temperature, Graphene Size, and Concentration on Aqueous Electrolyte Supercapacitors

The effects of electrolyte concentration (regulated by varying the amount of ethylene glycol), temperature, and graphene size (adjusted by expanding the original graphene unit cell to different extents) on the diffusion and structure of aqueous electrolytes in graphene supercapacitors were investigated using molecular dynamics simulations. By analyzing the average number of hydrogen bonds, number density distributions, mean square displacement, and diffusion coefficients, we found that temperature and concentration significantly influence the properties of the system, while graphene size has a minimal effect. As the concentration of ethylene glycol increases, the hydrogen bonding network among water molecules is gradually disrupted, leading to a decrease in the average number of hydrogen bonds between water molecules, while the average number of hydrogen bonds between water and ethylene glycol molecules increases. Ethylene glycol demonstrates a greater propensity for hydrogen bond formation compared to water molecules. Consequently, the addition of ethylene glycol effectively protects water molecules toward decomposition via electrolysis.