Bridge-grafted EG/BCN encapsulated PW with effectively improved thermal conductivity and battery thermal management performance

Although phase change materials (PCMs) have been widely utilized in thermal management of batteries, they still confront the challenges of high cost and low thermal conductivity. In this study, low-cost composite PCMs with high energy-storage capacity, thermal conductivity and outstanding thermal management performance were proposed by utilizing the synergetic porous structure of expanded graphite (EG) and boron carbon nitrogen (BCN) nanospheres through bridge-grafting method to encapsulate paraffin wax (PW), which effectively enhanced the anti-leakage and comprehensive performance. The incorporation of BCN nanospheres endowed the composite PCMs with extremely improved thermal conductivity of 1.611 W/(m·K), which was 421 % higher than that of pure PW. And the highly improved melting and crystal latent heat of the composite PCMs reached 184.37 J/g and 185.39 J/g, respectively, which also exhibited excellently thermal-cycling stability. The photo-thermal conversion efficiency of the composite PCMs was enhanced to 92.6 %. When applied to battery thermal management, the maximum temperature of battery wrapped with the composite PCMs was 11.9 °C lower than that of the batteries without PCMs, which confirmed an outstanding battery thermal management effect of the composite PCMs.