(614g) Ion Diffusion and Capacitance in Electrochemical Systems with Aqueous Electrolytes

Diffusion of ionic component in electrolytes not only changes the gradient of ion concentration but also alters the local dielectric environment. Despite the significant progress of non-equilibrium molecular theories on diffusion process driven by the gradient of ion concentration, the effect of kinetic dielectric decrement on ion diffusion dynamics is still poorly understood. Herein, taking the charging process in electric double layer system as a case study, we conduct a multiscale study of ion diffusion in aqueous electrolytes by combining the dynamic density functional theory and an ion-concentration dependent dielectric constant model. Using this method, we demonstrate that the time evolutions of local dielectric constant and ion concentration can be simultaneously predicted, and the coupling effect in between on the charging speed and differential capacitance is significant when the hydration ability of the ion is strong, in accordance with the experimental data.