Polydimethylsiloxane-based phase change composites with excellent low-temperature flexibility for battery thermal management

In recent years, phase change composites (PCCs) play an important role in battery thermal management systems (BTMs) due to their unique ability to store and release thermal energy without energy consumption. However, the high rigidity of traditional PCCs in cold environment may cause safety hazards and reduce service life of PCCs. In this work, a novel phase change composite with excellent low-temperature flexibility was fabricated using a straightforward method. Polydimethylsiloxane (PDMS), polyethylene glycol (PEG) and multi-walled carbon nanotubes (CNTs) were mixed at high temperature, and then PDMS-based PCCs with remarkable flexibility were acquired. The PDMS/PEG/CNTs exhibits excellent flexibility even at - 40 degrees C, along with a high crystallization enthalpy of 100.9 J/g and a melting enthalpy of 138 J/g. Combined with an appropriate crystallization temperature range of 29-42 degrees C and a melting temperature range of 47-66 degrees C, PDMS/PEG/CNTs demonstrates significant potential in BTMs. Results from the tests of battery thermal management on lithium-ion batteries (LIBs) showed that at ambient temperature of 25 degrees C, the surface temperature of battery cooled by PDMS/PEG/CNTs decreases by 10.4 degrees C compared to natural cooling when at a high C-rate of 3 C/4 C. This work fully utilizes the low-temperature resistance of PDMS to address the issue of PCCs becoming rigid and brittle in cold environment, thereby providing a promising strategy for the development of reliable and efficient BTMs based on PCCs.