NaF-NaCl/graphite foam composites for high-temperature latent heat storage applications

Fluorine and chlorine reciprocal salts are ideal media for high-temperature latent heat storage because of their high latent heat, wide sources and good chemical stability. However, low thermal conductivity, corrosion and leakage of molten salts limit its further development and application. In order to solve these problems, three kinds of high thermal conductivity graphite foams (GFs) with different pore structures were selected and combined with NaF-NaCl eutectic salts by vacuum impregnation to successfully prepare NaF-NaCl/GF composites with high thermal conductivity and high energy density. The designed composites have high thermal conductivity ranging from 31.3 W/m·K to 108.9 W/m·K, benefiting from the continuous heat transfer channels of the GF porous skeleton. The higher volume filling ratio (94.7–98.5 %) allows the composites to have high latent heat (331.8–556.6 J/g). In addition, the thermophysical properties of the composites remained stable after 50 thermal cycles. The results show that NaF-NaCl/GF composites have a potential application in high temperature heat storage.