Thermal behavior of a prismatic LiFePO₄ battery under fast charging: simulation and side-cooling enhancement

Abstract

The risk of thermal runaway caused by high-rate fast charging is one of the bottlenecks restricting the large-scale application of lithium-ion power batteries. In this paper, a prismatic LiFePO4 battery was selected as the research subject, and a three-dimensional electrochemical-thermal coupled model of that was built in COMSOL Multiphysics, in order to capture polarization behavior, heat generation characteristics, and temperature field evolution under constant-current charging at rates from 1C to 4C. Key focus is paid to two features: the anisotropic thermal conduction inside the jellyroll, and the current concentration near the tab region. The results show that the polarization overpotential significantly increases at high rates, and irreversible heat (polarization heat and Joule heat) becomes the main cause of temperature rise; the temperature field exhibits inherent non-uniformity, with hot spots consistently appearing at the positive tab-current collector connection, with a peak temperature of 32.9 ℃ at the end of 4C charging and an internal temperature difference exceeding 7 °C. To alleviate heat accumulation, an enhanced side heat dissipation strategy is evaluated: when the side convective heat transfer coefficient is increased to 40 W/(m²·K), the peak temperature during 4C charging decreases by 3.2 °C to 29.7 °C, and the temperature uniformity is significantly improved. This paper reveals the physical essence of fast charging thermal behavior in prismatic batteries and proposes a collaborative thermal management approach of “bottom cooling + side enhancement”, providing a theoretical basis for the thermal design of high-power battery packs.