COMSOL-Based Numerical Modeling of Zn2+ Transport in Glass-State Composite Cathodes for Aqueous Zinc-Ion Batteries

Aqueous zinc-ion batteries (AZIBs) are attractive for safe and low-cost stationary storage, but quantitative modeling of glass-state cathodes requires both physically consistent transport equations and independent rate validation.In this work, the original one-dimensional COMSOL framework for a ZFMP (ZnO-Fe2O3-MnO2-P2O5) glass-state composite cathode was corrected by enforcing a capacity-conserving mapping between external specific capacity and the internal cathode filling state.The continuum model couples Zn 2+ transport, charge conservation in the solid and electrolyte phases, and Butler-Volmer kinetics.A transparent power-law utilization factor was then added to represent the rate-dependent fraction of accessible active material without assigning the loss to an unverified microscopic mechanism.Three parallel cells at 50 mA g -1 gave 178.02 ± 0.70 mAh g -1 ; the corrected low-rate model reached 178.0 mAh g -1 with a voltage RMSE of 26 mV.The utilization exponent k = 0.138 was identified only from the 0.5 C capacity of 164.38 ± 0.59 mAh g -1 .With no further fitting, the hybrid model predicted 149.36 mAh g -1 at 1.0 C, compared with 149.97 ± 1.28 mAh g -1 experimentally, corresponding to a capacity error of 0.41%.The frozen continuum component reproduced the correct rate-dependent voltage ordering but overestimated high-rate capacity, whereas the hybrid framework separates mechanistic voltage polarization from semi-empirical utilization loss.This experimentally constrained approach provides a more defensible basis for interpreting Zn 2+ transport and rate capability in glass-state composite cathodes.