Abstract: An effective battery thermal management system(BTMS) is of great significance to ensure safety and extend the service life for lithium-ion batteries(LIBs). To obtain a more suitable operating temperature and better temperature uniformity of the battery module, an ultrathin flat heat pipe-liquid cooling BTMS is designed. An efficient optimization method based on one-dimensional(1D) equivalent thermal network model and three-dimensional(3D) numerical simulation model is developed by combining their advantages. Both of the 1D and 3D models are validated experimentally. To analyze the influence of four parameters on comprehensive performance of the proposed system, a four level orthogonal array is selected to quantify the parametric and perform multi-objective optimization. The optimization results suggest that both the thermal performance and lightweight are improved, where the maximum temperature can be controlled below 40 ℃. Additionally, the variable heat pipe length scheme can significantly improve the temperature uniformity of the battery module. The temperature difference of the battery module can be controlled below 2 ℃ under the high discharge and current changing discharge process in comparison with the original system. Besides, the accessories mass ratio is reduced by 8.2%.

Key words: battery thermal management, flat heat pipe, liquid cooling, equivalent thermal network, lithium-ion battery