Advanced electro-heat conversion properties of microcrystalline graphite-based composite phase change material with the three-dimensional framework

Abstract

Form-stable composite phase change material (PCM) with high latent heat is widely used in thermal energy storage application. The skeleton structure and thermophysical properties of the supporting material are greatly important to the energy efficiency of the composite PCM. This work is to design the supporting material with specific 3D carbon framework for composite PCMs using the CaCO3-templated assembly technique, following to explore the electro-heat conversion ability of composites. Microcrystalline graphite is used as the skeleton, CaCO3 as the template, and monocrystal white sugar as the carbon source. By designing the content of template, the 3D framework structure of supports can be tailored. Results show the designed support material has a higher cumulative pore volume than the raw material of 64 %, leading to an increment of the loading capacity of 12–20 %, due to the formation of the cotton-shaped carbonization connection products. Then, the stearic acid-type composite shows the thermal conductivity is improved by 104.86 % than the pure PCM, causing faster heat storage and release rate. At last, it proved that the electro-heat conversion of the composite can be achieved at low trigger voltage. The conversion efficiency increases with the voltage rising and the bulk density improving, reaching to 75.61 % at a voltage of 4.5 V with a bulk density of 0.774 g cm−3.