Shape-stable and fire-resistant hybrid phase change materials with enhanced thermoconductivity for battery cooling

Abstract

Thermal safety issues related to the thermal runaway problems in Li-ion batteries have been greatly concerned due to their wide applications. In this study, a low-cost and facile strategy for Li-ion battery thermal management was enabled by packing hydrated salt into organic paraffin and further stabilization of the composite by adsorption into a porous supportive material (expanded graphite, EG). The resultant composite phase change material (HPC@EG) demonstrated good shape stability and enhanced thermal conductivity (TC, 1.53–4.35 W m−1 K−1 at EG loadings of 5–15 wt%). HPC@EG also exhibited high latent heat (196.6 J/g) with sustained thermal storage performance over at least 500 heating / cooling cycles. The favorable performance of HPC@EG resulted from the paraffin acting both as a sealant and nucleating agent for the hydrated salt and as a co-phase change material, and the contribution of EG to the shape-stability and thermal conductivity. An added advantage of using hydrated salt and EG was their intrinsic fire-resistance which was also inherited by the HPC@EG composite. Such a combination offered effectiveness in preventing overheat of Li-ion batteries as we demonstrated, showing great promise in Li-ion battery thermal management in respect of price, safety and the cooling performance.