Simulation of Interface Characteristics and Charge Transfer Dynamics for Layered Electrodes Using Cascade Capacitance in Supercapacitors by COMSOL Software.

Abstract

In this investigation, the performance disparity between layer-by-layer (LbL) electrodes and uniformly mixed (UM) electrodes in supercapacitors is evaluated using COMSOL Multiphysics software by utilizing a two-dimensional asymmetric structure simulation model where the LbL electrodes consist of ZnMn₂O₄ and graphene oxide (GO) with varying layering sequences and scales ranging from millimeters to microns. The results revealed that the LbL electrodes significantly augmented the supercapacitor's performance by enhancing charge and mass transport mechanisms. Across both millimeter and micrometer scales, the LbL electrodes surpassed the uniformly mixed electrodes due to their larger surface area and greater ionic accessibility, resulting in more effective charge storage and faster electron transfer. Cyclic voltammetry (CV) illustrated that the peak current density of the LbL electrodes increased with an increase in layers with four-layer micrometer-scale electrodes displaying characteristics closest to those of an ideal supercapacitor, showcasing more consistent and efficient energy storage and release capabilities. The analysis using electrochemical impedance spectroscopy (EIS) revealed that the LbL electrodes exhibited reduced resistance and significant capacitive characteristics about 10⁹ F/m². The stacked structure not only improved the surface area and conductivity of the electrodes but also accelerated the charge transfer process, minimized interfacial reaction resistance, and facilitated ion diffusion within the electrodes. Through a combination of simulation techniques and theoretical analysis, this study proposed a stacked capacitance (C_s) theory and developed a cross-scale electrochemical interface model by integrating first-principles calculations with multiscale simulations. These findings provide valuable insights for designing and optimizing high-performance materials and devices, offering a new perspective on enhancing the supercapacitor performance through electrode design.