Microstructural Regulation of Ionic Transport in LiCoO2 Cathodes for Lithium-Ion Batteries: A Stochastic Reconstruction and Random-Walk Simulation Study

Abstract

Lithium-ion transport in LiCoO₂ composite cathodes is strongly governed by the complex three-phase microstructure composed of active material (AM), carbon-binder domain (CBD), and pore space. However, the independent effects of key structural parameters on ion transport remain insufficiently quantified. In this work, a statistically equivalent three-dimensional microstructure of LiCoO₂ cathodes was reconstructed using a stochastic method, and a random-walk simulation was employed to evaluate the effective diffusivity and tortuosity. The influences of porosity, CBD content, AM particle size, and particle size distribution were systematically investigated. The results show that increasing porosity from 0.20 to 0.60 significantly enhances ion transport, with the effective diffusivity increasing from 0.109 to 0.465 and tortuosity decreasing from 2.148 to 1.278. In contrast, higher CBD content compresses pore channels and increases transport resistance. Enlarging AM particle size improves pore connectivity, leading to increased diffusivity and reduced tortuosity. Moreover, a broader particle size distribution further enlarges characteristic pore size and slightly enhances ion transport. These findings quantitatively reveal the independent roles of key microstructural parameters and provide insights for optimizing electrode design toward improved ion transport performance.