Synchronously improved thermal conductivity and anti-leakage performance for phase change composite by SiC nanowires modified wood carbon

Abstract The low thermal conductivity and poor shape-stability of organic phase change materials (PCMs) have limited their applications in thermal energy storage. In this work, to deal with these issues, silicon carbide (SiC) nanowires modified wood carbon (C) with a three-dimensional (3D) architecture by direct carbonization and subsequent carbothermal reduction is employed as porous matrix for supporting paraffin wax (PW). In particular, SiC nanowires are introduced into the anisotropically aligned microchannels of wood carbon to form a secondary porous network, as a result, the 3D SiC/C skeleton can notably enhance the thermal conductivity and leakproof performance of the phase change composites (PCCs). In addition, thanks to the nature of wood carbon, the PCCs show anisotropically improved thermal conductivity, in which along the axial direction of wood carbon the thermal conductivity values are higher. The results show that the composites have an enhanced through-plane thermal conductivity (0.78 W m − 1K−1) compared to that of a neat paraffin (0.2 W m − 1K−1). As for the leakproof performance of the PCCs, the spider's web-like porous SiC sub-network in the microchannels of wood carbon can also offer additional capillary absorption force to liquid PW, so as to further enhance the anti-leakage property of wood carbon. Moreover, the PCCs also show excellent phase change reversibility, chemical stability upon long cycling and good photothermal conversion ability. This work provides a novel strategy for designing anisotropic structure for fabricating PCCs in advanced thermal management and storage.