Heat transfer and storage characteristics of composite phase change materials with high oriented thermal conductivity based on polymer/graphite nanosheets networks

Energy storage materials are being increasingly utilized. However, traditional solid–liquid phase change materials (PCM) have two disadvantages: low thermal conductivity and an inability to maintain stable properties. In this work, a novel anti-leakage, form-stable composite PCM with enhanced thermal conductivity was successfully proposed. This composite PCM uses a cross-linked mixture of paraffin wax and an olefin block copolymer as the base material and expanded graphite as the thermally conductive filler. The vacuum adsorption method and directional molding method were used to achieve shape stability and high thermal conductivity of the material. When the mass ratio of expanded graphite was increased from 5% to 30%, the corresponding thermal conductivity increased from 2.79 to 25.56 W∙m−1∙K−1, which was an improvement of 111 times compared to paraffin wax. When the mass ratio of expanded graphite reached 10%, the heat storage reached its maximum value of 520 J/ cm2, while the peak heat storage power reached 11.5 Wcm−2 with a 30% graphite mass fraction. Battery thermal management experiments showed that, the battery temperature rise could be effectively controlled within 17 °C. In the case of natural convection, the temperature rise reached 39 °C. The proposed composite PCM demonstrates promising potential for application in thermal management, building energy and heat storage.