DESIGN OF A PASSIVE COOLING SYSTEM FOR HIGH-CAPACITY AUTOMOTIVE BATTERY MODULES

Abstract

The high-capacity automotive battery modules' thermal performance is significant, such as vehicle reliability, charging ability, service life, and operating safety. The design and the evaluation of a passive cooling system based on a heat-spread plate and phase change material with no pump, fan, and additional electric power consumption to control the heat accumulation are given. The ambient temperature and discharge rate, operating time, cell position, thickness of phase-changing material, and repeated thermal cycles were investigated for the proposed system. The results showed that the passive cooling system was able to effectively reduce the peak temperature of the module for all the investigated scenarios. The maximum temperature is reduced from 68.2°C to 58.1°C for the uncooled and passive cooling, respectively, when ambient temperature is set at 45°C. It was possible to reduce the highest temperature from 59.8 °C to 51.8 °C under a 2C discharge condition. The optimized 7 mm phase-change-material layer resulted in a decrease of the peak temperature by 9.1°C, and the mass increment of the module was kept at 2.9%. The design of the system also resulted in better uniformity in the temperature, which decreased the cell-to-cell temperature difference from 6.2 °C to 3.2 °C. Moreover, the exposure time was cut by 61.9% even if it was increased to over 50 °C, and repeated-cycle tests demonstrated the thermal performance stability over 100 cycles. Based on the results, it is concluded that the maximum temperature can be reduced by 14.8% and the temperature non-uniformity can be reduced by 48.4% with the optimized passive cooling design without consuming any energy from auxiliary cooling. The results suggest that passive thermal management could be a suitable solution for high-capacity automotive battery modules, which is simple, reliable, and energy efficient.