Preparation and thermal performance of ternary carbonates/silica microcomposites as phase change materials

Microencapsulated phase change material (PCMs) is an effective thermal energy storage medium. In this paper, ternary lithium, sodium, potassium carbonates/silica microcomposites as PCMs were synthesized by a sol-gel coating method. The effects of heat treatment on the performance of the ternary carbonates and the microcomposites were studied. The composition, microstructure, phase change characteristics, and thermal stability of the microcomposites were characterized by Fourier transform infrared spectrophotometer (FTIR), scanning electron microscope (SEM), differential scanning calorimeter (DSC), and X-ray diffraction (XRD). Results show that different carbonate eutectics were detected with or without heat treatment. The microcomposite with heat-treated ternary carbonates exhibited a latent heat of 192.2 kJ/kg and an encapsulation ratio of 84.8%. The supercooling degree was reduced by 43.7%. No leakage was detected after phase change cycles, indicating good thermal stability of the microcomposite. The results indicate that the microcomposites have great potential in high-temperature thermal energy storage. [Figure not available: see fulltext.]