Experimental Validation and Three-Dimensional Thermal Modeling of a LiFePO₄ Pouch Cell Under Varying Operating Rates and Ambient Temperatures

The thermal behavior of lithium-ion batteries strongly affects their performance, safety, and service life in electric vehicle and energy storage applications.In this study, a three-dimensional transient thermal model of a commercial 20 Ah LiFePO₄ pouch cell was developed in COMSOL Multiphysics and validated using experimentally measured charging and discharging temperature data.The model was evaluated at ambient temperatures of 5 °C, 15 °C, 25 °C, and 35 °C under 1C, 2C, 3C, and 4C operating rates.The validation results showed good agreement between simulated and experimental temperature profiles.For charging, the model achieved an average maximum-temperature error of 0.034 °C and a maximum error of 0.308 °C.For discharging, the average final-temperature error was 1.390 °C, and the model consistently reproduced the discharge-rate-dependent temperature trends.Full-profile RMSE and MAE metrics were also evaluated over the complete transient temperature profiles, confirming that the model captures the overall temperature evolution under both operating modes.The main contribution of this work is the systematic validation and comparative analysis of charging and discharging thermal characteristics of a commercial LiFePO₄ pouch cell over a broad matrix of ambient temperatures and C-rates.The results show that battery thermal behavior is strongly influenced by operating rate and ambient temperature.During charging, max T increased from 9.49 °C at 1C to 18.24 °C at 4C under 5 °C and reached 41.47 °C at 4C under 35 °C.During discharging, temperature rise increased from 2.23 °C to 11.45 °C as the discharge rate increased from 1C to 4C at 5 °C.Overall, the validated model provides a reliable framework for battery thermal analysis, safe operation, and improved thermal management design.