Thermal management of Lithium-ion battery pack through the application of flexible form-stable composite phase change materials

Highlights: • Flexible styrene–butadiene–styrene (SBS) based phase change materials (PCM) is proposed. • SBS can well maintain the structural stability of the composite materials. • Expanded graphite can obviously increase the thermal conductivity of composite PCM. • SBS based composite PCM exhibit an excellent battery thermal management effect. Phase change materials (PCM) have become a research interest in the area of passive heat dissipation owing to many advantages, such as simple structure, high latent heat, low cost and so on. However, due to their low thermal conductivity, easy leakage, and poor mechanical properties, PCM have limited application, especially in battery thermal management. In this study, a novel flexible composite SBS@PA/EG is successfully prepared by dissolving in an organic solvent and utilized in battery thermal management (BTM) system. Here, styrene butadiene styrene (SBS) as a supporting material, paraffin (PA) as a phase change material and expanded graphite (EG) as a thermal conductivity enhancer. The chemical properties and structure of the composite PCM are analyzed by X-ray diffractometer, scanning electron microscope and thermal conductivity measurements, moreover, the stability is analyzed through measuring the tensile/bending strength. Besides, the relationship between the maximum temperature and temperature difference with state of charge for battery module are analyzed. During the 5 C discharge process, the maximum temperature of the battery module can be maintained below 46 °C and the temperature difference be controlled within 4 °C. Thus, it should be concluded that flexible form-stable composite SBS@PA/EG can be applied well in BTM system and more extensive thermal management systems.