Modelling of heterogeneous structure and particle-scale analysis of LiFePO4 electrode

In electrochemical systems, electrodes are the core components of energy storage and conversion devices. However, the porous structure of electrodes limits the performance of active material particles. In order to explore the influencing factors and perform quantitative analysis at the electrode particle scale, a heterogeneous model of LiFePO4 battery is developed. In the model, battery polarization effects are distinguished at the particle scale as kinetic polarization, electrode/electrolyte lithium concentration polarization, and ohmic polarization. Numerical simulations are performed using a validated model, and the results show that the electrode porous structure influences the distribution of electrochemical reactions and the mass transfer process, disrupting the consistency of interparticle properties. During battery operation, each polarization undergoes significant fluctuations and exhibits an uneven distribution across the electrode, with values differing by more than 80 times near the separator and collector. The lithium concentration analysis further shows that the concentration difference between two sides of the electrode reaches 8416.81 mol·m−³ influenced by the porous structure. Based on these results, electrode structure optimization measures are then proposed, and the simulation results show significant performance improvement with smaller polarization voltage loss. This work provides novel insights and methodologies for elucidating battery operation principles and optimizing electrode structure.