High thermal conductivity composite phase change material with nano-Ag particles modified diatomite and expanded graphite for improving battery thermal management efficiency

Composite phase change materials (CPCMs) with significant amounts of latent heat can absorb and release at a constant transition temperature have attracted much attention in energy storage and electrical vehicles fields. Nevertheless, it is still a great challenge to utilize in battery thermal management system owing to low thermal conductivity and liquid leakage. Although many efforts have endeavored to improve transferring heat capacity, the thermal conductivity of CPCM is still need to explored. Herein, a novel high thermal conductivity and anti-leakage CPCM including polyethylene glycol, nano-Ag particles modified diatomite and expanded graphite (PDAE) has been designed and prepared. And the nano-Ag particles have evenly attached to the surface of diatomite through in-situ chemical reduction reaction and self-assembly technology. The experimental results indicate that PDAE exhibits excellent thermal conductivity with 1.91 W∙m−1∙K−1 owing to three-dimensional heat transferring network constructed by nano-Ag particles and expanded graphite. Moreover, it is no shape variation and leakage of PDAE under continuously heated at 60 °C for 2 h. In addition, the temperature performance of battery modules with the different CPCMs have been compared in detail, the results demonstrates that battery module with PDAE can be maintained below 53 °C and the temperature difference is effectively controlled within 5 °C even at 3C discharging rate after 10 cycles. With these prominent performances, this designed CPCM with high thermal conductivity will offer a promising insight into the passive thermal management system in practical application.