Warming‐Up Effects of Phase Change Materials on Lithium‐Ion Batteries Operated at Low Temperatures

Lithium‐ion battery performance is strongly dependent on thermal conditions, deteriorating dramatically at low temperatures. Herein, a passive thermal management system utilizing RT28/fumed silica composite phase change materials (PCMs) is evaluated for a lithium‐ion battery at temperatures below 5 °C. Taking advantage of the high thermal energy storage capacity, PCMs can store heat and keep a battery warm. The cells with PCMs take much longer before being too cold than cells without PCMs. The improved thermal conditions lead to higher voltages and discharge capacities. In the long term, PCMs increase the average temperature of the battery in continuous cycles and prolong their cycle life by up to 76 %. But the extra thermal mass of the PCM slows the temperature rise so that the cell with PCM fails to perform well at the beginning stages in cold environments.