Enhanced thermal conductivity of phase change composites with novel binary graphite networks

The thermal conductivity and porous structure of carbon-based networks significantly affect the heat exchange efficiency in phase change composites. However, simultaneously improving its thermal conductivity and controlling the formation of micrometer-scale open pores remains a significant challenge. In this study, a binary graphite network is constructed by both high-thermal-conductivity mesophase-pitch carbon fibers and high-textured pyrolysis carbon through chemical vapor deposition and ultra-high temperature graphitization, then embed paraffin to form high-performance phase change composites. The characteristic hierarchical pore structure in the binary graphite network facilitating the paraffin impregnation and its heat exchange efficiency is greatly improved by showing an optimum thermal conductivity of 144.78 W·m⁻¹·K⁻¹ and a phase change enthalpy of 87.4 J·g⁻¹ at 0.6 g·cm⁻³ graphite skeleton and 51 wt% paraffin. The developed phase change composites hold great application potential in thermal control for space optical-mechanical systems and other critical aerospace components.