Experimental investigation on thermal management performance of electric vehicle power battery using composite phase change material

The development of electric vehicles (EVs) is beneficial to a cleaner environment. As the powertrain of EVs, power battery is limited obviously by its fast operating temperature rise and large temperature variation among different parts, so an efficient battery thermal management (BTM) system is desirable. In this paper, a battery thermal management system using kaolin/expanded graphite (EG)/paraffin composite was designed. By contrasting different thermal properties of ternary composites with various proportions, the most suitable composite with 10 wt% EG and 10 wt% kaolin was selected for the thermal management testing, which has a conductivity of larger than 6 W/(m·K) and did not shows any visible leakage after 30 min at 60 °C. In the thermal management test, the temperature of a single battery was effectively controlled under 45 °C even at the discharge rate of 4C, and the temperature difference of the single battery was restrained within 5 °C. Besides, the composite had reduced the temperature of the battery pack by 25.77% at 4C rate, and the temperature difference of the battery pack or each battery in the pack could be greatly controlled once the phase change occurred. In conclusion, the excellent temperature controlling performance of the new phase change material (PCM) was verified in this paper, and the importance of reasonable dosage distribution of PCM in battery pack was put forward.