The multifunctional organic phase change materials for battery thermal safety in electric transportation systems: A critical review

Electric transportation systems are great alternatives to conventional fossil-fuel-powered transportation systems. The thermal safety of high-energy-density lithium-ion batteries (LIBs), which are the main energy source in electric transportation systems, is one of the most major challenges facing the applications of these systems. Phase change material (PCM)-based battery thermal management systems are an effective solution for battery thermal safety, and they have a great application potential. However, the thermal safety of LIBs involves thermal management and thermal runaway protection, which require composite PCMs (CPCMs) with excellent thermal management cooling effect and stable thermal runaway protection capability. Thus, the optimizing strategies used for enhancing the structural stability, thermal conductivity, and flame retardancy of CPCMs were compared and analyzed. Moreover, the design of PCMs with thermal management and thermal-runaway-flame-retardant suppression capabilities was discussed. Finally, future research directions for using multifunctional PCMs in battery thermal safety systems were proposed based on critical thinking. This review will provide new insights and attract considerable attention to the reliability of thermal safety systems based on multifunctional PCMs in future designs, especially in the field of battery thermal safety.