Exploration of electrode structure optimization based on a heterogeneous electrode model: Analysis of polarization effect under the regulation of particle morphology

In the practical application of lithium-ion batteries, the polarization effect is a key factor affecting their stability, voltage plateau and other performances, and is closely related to electrode porous structure. In order to improve battery performance from the perspective of electrode structure optimization, two electrode particle morphology regulation methods, ion channel electrode (ICE) and gradient particle-size electrode (GPE), are proposed within a validated LiFePO4/graphite battery heterogeneous electrode model framework. The regulation mechanism of the electrode porous structure is explored by analyzing the polarization effect at electrode particle scale (mesoscale) and its relation to battery output characteristics. Results show that, GPE with decreasing particle size from separator to collector effectively coordinates solid-phase/liquid-phase diffusion and reaction distribution in the electrode thickness direction, reducing peaks of electrode kinetic polarization and concentration polarization by over 50 % near collector; opposite effect occurs when the particle-size gradient of GPE is reversed. Ion channel of ICE enhances the "long-range" diffusion of lithium ions, leading to nearly 60 % reductions in concentration polarization and ohmic polarization in the electrolyte. Both methods effectively mitigate the polarization effect, optimizing overall battery performance. These results provide new ideas for electrode preparation and are expected to improve battery performance by optimizing electrode structure.