Thermal‐Conductivity‐Enhancing Copper‐Plated Expanded Graphite/Paraffin Composite for Highly Stable Phase‐Change Materials

Abstract Paraffin (PA)/expanded graphite (EG) is an important composite phase change material with low cost, high heat storage, good thermal conductivity and cycling stability. Its thermal conductivity needs to be further improved for application in the thermal management system of power lithium‐ion batteries. In this paper, copper plated expanded graphite (CPEG) with 3D porous structure was prepared by electroless copper plating method, which was used as thermal conductivity enhancing material to replace part of EG in PA/EG composite materials. For the optimized phase change material composed of 80 %PA‐14 %EG‐6 %CPEG, the copper content is very low (0.768 wt %), but its thermal conductivity can be significantly improved without loss of latent heat and thermal cycling stability. Its thermal conductivity is increased from 11 times to 16.5 times that of paraffin while compared with the copper‐free composite material (80 %PA‐20 %EG). The PA/EG/CPEG composite material exhibits good temperature control effect on power lithium‐ion batteries.