This work focuses on the effects of charged single-walled carbon nanotubes (SWCNT) on the heat capacity of composite carbonate salt (Li2CO3-K2CO3) using the Electric Double-Layer modeling (EDL) and the Molecular Dynamics (MD) simulation. The nanoparticle-enhanced molten salt ensemble is modeled considering the compressed ion layer surrounding the SWCNT, and the specific heat capacity (c(p)) enhancement of the nanoparticle-enhanced molten salt is analyzed. The results present the following issues. First, compressed ion layer is formed around the SWCNT surface. The density distributions of Li+, K+ and CO32- are strongly related to the SWCNT charge. The density distributions of the ions present characteristics of oscillatory, and the densities of the ions can be increased by rise of SWCNT charge. Second, the charge density distribution is analyzed. The local enrichment of positive and negative charges is found to occur inside the compressed ion layer. It is found that increasing the SWCNT charge can promote the local enrichment of positive and negative charges, which contributes to the increase of the internal energy of the nanoparticle-enhanced molten salt ensemble and results in c(p) enhancement. Finally, c(p) is found to be increased with increasing SWCNT charge. The c(p) enhancement of 19.2% is achieved when the SWCNT carries surface charge of -280e. The obtained results can provide guidance on the application of charged nanoparticles to enhance the specific capacity of molten salt.