Comprehensive Application of Phase Change Materials in Lithium‐Ion Battery Thermal Management: From Single Cooling to Coupled Systems

Phase change materials (PCMs), renowned for their superior heat storage capabilities, face the challenge of inherently low thermal conductivity (k). This review comprehensively examines strategies to enhance PCM k and thermal energy storage density across four fronts: single component optimization, composites with varied composition ratios, advanced processing technologies, and doping with small molecules. Notably, including 10% expanded graphite in paraffin has been shown to enhance thermal conductivity by over ten times that of pure paraffin. The integration of PCM cooling with air and liquid cooling methods leverages the high heat storage capacity of PCMs and the rapid heat transfer capabilities of these other cooling methods, effectively controlling battery temperatures and reducing temperature gradients within the battery module. For instance, combining PCM with air cooling has been demonstrated to minimize maximum temperatures (Tm) and temperature differences (Td), maintaining Tm within an ideal range of 2 °C. Despite these advantages, further research is warranted to address the limitations of PCMs, such as their limited heat absorption and extended thermal recovery periods, to broaden the application of PCM cooling technology.