Porous SiC/NaCl-KCl composite phase change materials with enhanced thermal conductivity via structural inheritance from graphite foam

Abstract

NaCl-KCl eutectic salts possess high thermal stability, high energy storage density and low cost, representing one of the most promising phase-change thermal storage materials for next-generation concentrated solar power technology. However, its low thermal conductivity and susceptibility to leakage and corrosion hinder practical applications. Herein, employing a structural inheritance strategy based on an adjustable graphite foam (GF) template, a three-dimensional (3D) interconnected porous SiC scaffold is fabricated by reactive melt infiltration (RMI) process for encapsulating NaCl-KCl molten salts. GF templates are completely converted into SiC, with no residual Si or C. The porous SiC retains a compressive strength of 12.14 MPa even when its open porosity reaches 79.7%. The thermal conductivity of the developed porous SiC/NaCl-KCl composite phase change materials (CPCMs) reaches as high as 20.34 W/m·K, along with a latent heat of 194.0 J·g −1 . Additionally, the prepared porous SiC/NaCl-KCl CPCMs exhibit excellent thermal cycling and thermochemical stability. After 50 charge-discharge cycles, the latent heat of CPCMs remains at 181.2 J·g −1 , and no reaction occurred between the porous SiC and the molten salt. This work demonstrates a structural inheritance strategy based on adjustable GF templates for fabricating high-performance porous SiC scaffolds, providing valuable insights for the structural design of high-temperature thermal energy storage materials.