Research on temperature non-uniformity of large-capacity pouch lithium-ion batteries: Modeling, analysis, and optimization

Large-capacity lithium-ion batteries (LIBs) are widely used in electric vehicles and energy storage systems, but display undesired temperature non-uniformity during operation due to the uneven heat generation of different components, resulting in disparate aging within the battery and further affecting their longevity and dependability. To clarify the impact factor of operational temperature differentials on large-capacity LIBs and to improve the temperature distribution uniformity, we develop a coupled electrochemical-thermal multiphysics finite element model to capture essential electrical and thermal battery characteristics. The reliability of the proposed model has also been verified by experimental results with an error margin below 10 % and a relative voltage error of only 0.7 % under various operation conditions. The model is further used to investigate the impact factors including initial temperature, initial state of charge (SOC), discharge C-rate, tab placement, and dimensional specifications on the dynamic battery temperature distributions during operation. Accordingly, the temperature uniformity of the large-capacity battery is optimized by refining tab configurations at the cell level and thermal management structure design at the module level. The results show a significant improvement of 40.3 % in temperature uniformity for a 48 Ah pouch lithium battery tested under 2 C discharge condition. Additionally, the proposed thermal management framework is also useful in low-temperature heating scenarios, demonstrating its broad applicability in battery thermal management domains.