A Study on the Influence of Ion Steric Effects in Electrodeposition

Abstract

The study investigates the complex interactions of ions near the electrode surface, where phenomena such as ion overcrowding and overscreening significantly influence ion transport and electrokinetic behavior. Under the application of a large voltage, intense electrostatic forces act on ions near the electrode, causing substantial modifications to the electric double layer (EDL) structure and the spatial charge distribution. These effects are particularly pronounced in systems with high ionic concentrations, where steric hindrance and ion size disparities become critical. The classical Poisson-Nernst-Planck (PNP) model is inadequate for describing these phenomena, as it neglects steric effects and fails to account for ion-ion interactions in dense ionic environments. To overcome these limitations, the modified Poisson-Nernst-Planck (mPNP) model is employed. This model incorporates key factors such as ion size effects and ion-ion interactions, enabling the accurate simulation of phenomena including the formation of densely packed EDLs and ion dispersion under extreme conditions. Additionally, the mPNP equations are coupled with the Navier-Stokes equations to provide a comprehensive representation of ion transport and fluid dynamics. This integrated framework facilitates a deeper understanding of the interplay among electrostatic forces, fluid flow, and steric hindrance, offering critical insights into the behavior of electrochemical systems under high-voltage and high-concentration conditions.