Safety issue on PCM-based battery thermal management: Material thermal stability and system hazard mitigation

Although lithium-ion batteries are increasingly being used to achieve cleaner energy, their thermal safety is still a major concern, particularly in the fields of energy-storage power stations and electric vehicles with high energy-storage density. Therefore, the battery thermal management systems (BTMs) have been extensively applied, among which phase-change-material (PCM)-based BTMs are being developed at a high growth rate. As highlighted here, because of the risk of battery thermal hazards such as thermal runaway or battery fires, meeting the prerequisites of PCM-based BTMs is imperative not only for aiding in heat dissipation in regular operation conditions, but also for facilitating thermal hazard mitigation in the case of extreme accidents. The thermo-physical properties of modified PCMs are compared, highlighting their thermal stability and flame retardancy. Structure-enhanced PCM-based BTMs are compared in terms of their structural design for hazard mitigation. Finally, future research directions based on critical thinking are proposed for the use of PCM-based BTMs in system resilience. We anticipate that this review will provide new insights and draw more attention to the material/system reliability of self-safety PCM-based BTMs in future designs, especially in terms of thermal safety issues.