Development of phase change material nano composite for thermal managment of lithium ion batteries used in hybrid-electric vehicles

Share of CO2 emissions from transportation is 26% of in the world and 17% in Turkey. By increasing hybrid/electric (HEV/EV) cars by 20% until 2020, CO2 emissions are expected to decrease by 5,2% in transportation sector and 1,3-3% in total emissions. The main barrier for spreading of HEV/EV technology is the energy storage systems that can provide acceptable range in competitive volume and size economically and in a secure way. The foremost security risk in Lithium ion batteries, which are one of the recommended systems, is thermal instability due to overheating. At normal current/ resistance levels and operating conditions, temperature of Lithium ion cells has to be kept in the range of 20-55°C. Capacity of the battery falls significantly at operating temperatures higher than these and at higher temperatures explosion as a result of thermal run away can occur. In this study, a new thermal management prototype for Lithium ion batteries using phase change material (PCM) nano-composite has been developed. Urban driving cycle performance tests done at different ambient temperatures showed that temperature of the battery pack without PCM protection can go up to 80°C even at 30°C ambient temperature, whereas with PCM+10% nanomagnetite maximum temperatures were 40°C less and stayed within secure temperature at all ambient temperatures tested. Hence, a secure operation of the battery was made possible and also by providing a homogeneous temperature distribution in the battery its life time can be prolonged.