Lithium‑iron-phosphate battery electrochemical modelling under a wide range of ambient temperatures

The performance of lithium‑iron-phosphate batteries changes under different ambient temperature conditions and deteriorates markedly at lower temperatures (< 10 °C). This work models and simulates lithium‑iron-phosphate batteries under ambient temperatures ranging from 45 °C to −10 °C. Essential modifications based on an existing electrochemical model are carried out to improve simulation accuracy at lower ambient temperature. Excitation response analysis and a multi-group particle swarm optimization algorithm are used to identify the model parameters. The simulation results indicate that when the ambient temperature is 20 °C or above, the mean absolute errors of the terminal voltage are within 20 mV. And at lower temperatures of −10 °C to 10 °C, the mean absolute errors of the terminal voltage are 9–14 mV for single cells and 11–21 mV for battery packs. Analytic function methods including Hermite interpolation, polynomial fitting, and sinusoidal fitting are adopted to address the uncertainties of model parameters at uncertain ambient temperatures for practical application.