Numerical investigation of battery thermal management by using different phase change materials under extreme working conditions

Owing to increasing globally interest on electrical vehicles, battery thermal management (BTM) issue has critically importance in increasing the life time and safety, decreasing the charging time and cost and weight of the electrical vehicles. Li-ion cells are preferred due to high energy density and lo self-discharge rate, long cycle life. BTM by using phase change materials (PCMs) is sensible due to the melting temperature of PCM is in the range of desired temperature of Li-ion cells. This study aims to compare the performance of different PCMs such as paraffin and n-octadecane to cool a Li-ion cell which are used in electrical vehicles. Time dependent numerical analyzes were conducted to show the performance of PCMs on the BTM at cycle time of 20,000. Boundary condition for the numerical analyzes were considered as different discharging time such as 1C, 3C and 5C. As a result, paraffin appears to undergo a phase change longer than n-octadecane. This is because the paraffin has a higher latent heat value compared to n-octadecane. According to the results, it was able to keep cell temperature between 258-313K by using paraffin at a discharge rate of 1C and 3C. However, n-octadecane was not able to keep the temperature of the cell at desired range at discharge rate of 3C. At 5C discharge rate, neither paraffin nor octadecane could provide the desired cell temperatures. On the other hand, both paraffin and n-octadecane ensured that the temperature difference in the cell remained below 2.5K at all discharge rates.