Thermal optimization of composite phase change material/expanded graphite for Li-ion battery thermal management

Abstract

Paraffin (RT44HC)/expanded graphite (EG) composite phase change material (CPCM) with enhanced thermal conductivity improves the thermal management of Li-ion batteries. The thermal management of these batteries may be further improved via optimizing the CPCM composition. In this study, the thermal management performance of CPCM, with different mass fractions of EG, is investigated for Li-ion batteries. CPCM samples were prepared by absorbing RT44HC into porous EG. The properties of composites, such as thermal conductivity and liquid phase change material (PCM) leakage, were measured. Our results show that: (1) EG incorporation dramatically enhances the thermal conductivity of CPCM and leads to a significant decrease in the temperature rise of Li-ion batteries; and (2) CPCM, with EG mass fractions varying from 9% to 20%, shows outstanding thermal management performance. Liquid PCM leakage, which decreases with an increase in EG loading, occurs during phase transition. We propose, taking into account liquid PCM leakage during phase transition, that CPCM with 16–20wt.% EG can be viewed as the most promising alternative for Li-ion battery thermal management.