High thermal conductivity phase change composite with a metal-stabilized carbon-fiber network

To enhance the thermal conductivity of phase change materials (PCM) such as sugar alcohol and molten salts, the preparation of a phase change composite (PCC) with a PCM and a filler with high thermal conductivity has been widely investigated. Although many reported PCCs have high thermal conductivity, the stability during thermal cycling endurance is often too low for practical use. This paper describes the development of a PCC with both high thermal conductivity and high cyclic durability. The PCCs were prepared by a hot-pressing method. Erythritol (melting point: 118 °C, thermal conductivity: 0.73 W m−1 K−1) was used as a PCM, and carbon fiber (thermal conductivity: 900 W m−1 K−1 in the fiber direction) and indium particles (thermal conductivity: 82.8 W m−1 K−1) were used as the high thermal conductivity fillers. The effective thermal conductivity of the PCC was measured using the laser flash method and the network structures were analyzed using energy dispersive spectroscopy and scanning electron microscopy. Thermal cycling tests through the melting and solidification phases of the erythritol were performed to investigate the cyclic durability of the PCCs. We found that the indium particles melted during hot pressing, welding together the carbon fiber to produce a stable percolating network, which significantly enhanced the thermal conductivity and cyclic endurance of the PCCs.