Development of 2D-Mt/SA/AgNPs microencapsulation phase change materials for solar energy storage with enhancement of thermal conductivity and latent heat capacity

Abstract

Application of clay mineral based phase change materials (PCMs) on solar energy storage was limited by poor latent heat storage and thermal conductivity. In this study, two-dimensional montmorillonite/stearic acid/Ag nanoparticles (2D-Mt/SA/AgNPs) composites were prepared to enhance the latent heat capacity and thermal transfer ability. It was found that the composites possessed ultra-high latent heat storage (>187 J/g) and contained more than 90 wt% of SA. Besides, 2D-Mt/SA/AgNPs showed 229.3% increase in thermal conductivity after incorporation of AgNPs into the core of composite PCMs, compared with pure SA. In addition, 2D-Mt/SA/AgNPs exhibited remarkable thermal charging/discharging rate and outstanding light-thermal conversion ability due to the excellent heat transfer ability. Because of the excellent thermal stability and structure reliability, 2D-Mt/SA/AgNPs showed superior cycling performances in the heating/cooling tests. As a consequence, 2D-Mt/SA/AgNPs were promising sustainable energy storage materials owing to large latent heat, high thermal conductivity, outstanding thermal stability and excellent cycling performance.