Numerical investigation on gradient liquid cooling plate of lithium-ion battery pack

The heat dissipation system of lithium-ion battery (LIB) pack is essential for ensuring its longevity and operational safety. However, the coolant flow within the system leads to a gradual accumulation of heat, causing the coolant temperature to increase along the flow direction. This phenomenon results in uneven temperature distribution within the LIB module, which affects the cooling efficiency and the stability of the LIB. To address this challenge, this study introduces a gradient structure design (GSD) and establishes a liquid cooling experimental platform for validation. Comparative experiments are conducted between the GSD and the conventional non-gradient structure to evaluate the cooling performance. Additionally, numerical simulations are performed to investigate the effects of coolant inlet flow rate, cold plate height gradient, and length gradient on the thermal performance of the LIB module. The results demonstrate that, compared to the conventional non-gradient structure, the GSD reduces the maximum temperature and the temperature difference by 5.08 % and 23.56 %, respectively. Moreover, increasing the cold plate height gradient progressively reduces both the maximum temperature and temperature difference, with a stabilization occurring at the height gradient interval of 5 mm. Compared with the uniform gradient structure, the optimized reinforced end structure achieves a 1.29 % reduction in peak temperature and an 8.63 % decrease in temperature difference, significantly improving the temperature uniformity and heat dissipation performance of the LIB module.