Phase change material coat for battery thermal management with integrated rapid heating and cooling functions from -40 °C to 50 °C

Authors：Luo, Mingyun; Song, Jiaqi; Ling, Ziye^*; Zhang, Zhengguo^*; Fang, Xiaoming

Source：Materials Today Energy, 2021, 20: 100652.

DOI：10.1016/j.mtener.2021.100652

• Electro-to-thermal conversion
• Electrically conductive cPCM
• Fast preheating
• Full-temperature thermal management

This study reports an electric-conductive paraffin/expanded graphite (EG) composite phase change material (cPCM) for thermal management of lithium-ion battery in a harsh environment. In this cPCM, EG provides a support matrix for paraffin to prevent liquid leakage, as well as a network for thermal and electrical conduction. EG (20 wt%) gives the non-conductive paraffin with a low resistance 0.1-0.28 Omega mm, but also enhances its thermal conductivity by up to 960%. A numerical model has been developed and validated to reveal the mechanism of this full-temperature thermal management. This cPCM integrates heating and cooling together, thereby preheating batteries with Joule heat effect, and cooling down the battery with the thermal storage. At a voltage of 3.4 V, cPCM can heat an eight-cell module at 13.4 degrees C/min with a maximum temperature difference between cells, 3.3 degrees C. Meanwhile, the cPCM can also reduce the battery temperature from 77 degrees C to 43 degrees C during a high-rate discharge (3C). The battery temperature can be maintained within 20 degrees C-55 degrees C for the entire discharge process. This full-temperature thermal management can be extended to an enlarged battery pack consisting of seven modules, which provide a comfortable thermal environment of 20-55 degrees C for the batteries under extreme conditions of -40 similar to +50 degrees C. This work broadens the application of PCM from a mere cooling function to a full-temperature thermal management.