Discharge Model for LiFePO4 Accounting for the Solid Solution Range

A comprehensive discharge model for LiFePO 4 electrode, including Li-ion diffusion in both the alpha and the beta solid solution phases, and phase transformation was developed. For the discharge model, the phase transformation, driven by the interfacial lithium concentration differences in both alpha and beta phases, was considered to be strongly dependent on the type of interface formed between the alpha and beta phases (coherent, semicoherent, and incoherent). By using the model as a tool, effects of extending the alpha and the beta solid solutions and reducing the particle size of LiFePO 4 on rate performance of LiFePO 4 were analyzed. The model developed in this article is applicable for predicting the discharge behavior of any other electrodes with phase transformation.