Incorporated surfaces and confined spaces of Na2HPO4·12H2O–Layered vermiculite nanosheets for phase change materials with enhanced thermal properties

Abstract

The phase change process of hydrated salts with a large latent heat and non-flammable characteristics is a promising route for achieving energy-efficient devices. To improve the reliability of the inorganic phase change material (PCM) system, excellent heat storage capacity, low supercooling degree, and good stability of hydrated salts are required. In this study, novel Na2HPO4·12H2O (DHPD)–vermiculite nanosheet (VMTNS) composite PCMs (CPCMs) possessing both surfaces and confined spaces were theoretically designed and synthesized. Incorporating the environmentally friendly VMTNSs, a new type of nano-reinforced fillers with multiple active sites, into DHPD hydrated salt results in excellent crystallization, great diffusion ability (33.277 × 10−11 m2/s), a low supercooling degree (0.8 °C), a high latent heat of melting (260.7 J/g), and great thermal stability of CPCMs. The DHPD arrangement both in the confined spaces and on the surfaces of the VMTNSs was simulated via molecular dynamics calculations. It was found that the adsorption energy of DHPD in the confined spaces of the VMTNSs and on their surfaces is –5.991 and –5.543 eV, respectively. This study provides an innovative method to construct novel CPCMs for efficient energy storage.