Numerical investigation on a unitization-based thermal management for cylindrical lithium-ion batteries

Abstract

Liquid cooling (LC) performs better than various other cooling technologies for battery thermal management (BTM) in electric vehicles (EVs), attributed to its high efficiency and low power consumption. However, the LC system for cylindrical lithium-ion batteries (CLIBs) has been scarcely designed and studied from the perspective of BTM unitization. In present work, a solution of unitization-based BTM with a novel distributed water-cooling component was proposed. Then, in COMSOL software, the multi-physical-field model of BTM system was carefully built to investigate the effects of three important system parameters (Vef, Ncc, and Tin) on the system performance. The results show that all the three parameters required determining moderately for balancing the system cooling performance, power consumption, and lightweight. Via stepwise analysis, the relatively optimal values of Vef, Ncc, and Tin were found to be 9 × 10−7m3s−1, 4, and 34 °C respectively. In this case, Tmaxm was controlled at 38.95 °C with ΔTmaxm as 4.36 °C, which could also well meet the battery temperature requirement under the unfavorable conditions of high ambient temperature (35 °C) and large discharge C-rate (3 C). Comparatively, Tin more significantly influenced the transient thermal behavior of BTM system, and should not be lower than 32 °C. For the temperature distribution, the results of this study are superior to those in the referred literature at both the battery and module levels. In particular, such an advantage is favorable to improve the performance consistency among battery cells, and thus helps to prolong the lifespan of battery module/pack. In practical EV applications, the BTM unitization enables the restraining of thermal runaway propagation in battery system. This study can provide valuable reference to design and study the LC-BTM system of CLIBs in EVs.