Effect of solvent on specific heat capacity enhancement of binary molten salt-based carbon nanotube nanomaterials for thermal energy storage

• Specific heat of molten salts was remarkable enhanced by dispersing carbon nanotubes.
• The solvent of nanomaterials strongly affects the enhancement of the specific heat.
• Formation of compressed liquid layers was observed by MD simulations.
• The different chemical composition of the solvent was observed in the compressed regions.

The specific heat capacity of a binary molten salt-based carbon nanotube nanomaterial was experimentally measured in both solid and liquid phases. The effect of the solvent on the specific heat capacity was examined for a wide range of chemical compositions for a binary carbonate salt mixture. The binary salt mixture consisted of lithium carbonate and potassium carbonate. Multi-walled carbon nanotubes were dispersed in the solvent to synthesize the nanomaterials. A surfactant, gum arabic, at 1% mass concentration with respect to the solvent was added to disperse the carbon nanotubes homogeneously in the salt mixture. The results indicated that the specific heat capacity of the carbonate salt mixtures was significantly enhanced by adding the carbon nanotubes in the solid and liquid phases. Moreover, the enhanced specific heat capacity was affected by the chemical composition of the salt mixtures. Furthermore, molecular dynamics simulations were used to examine the effects of different chemical compositions of the binary salt mixtures with nanotubes on the specific heat capacities of the nanomaterials.