H2O2-microwave treated graphite stabilized stearic acid as a composite phase change material for thermal energy storage

Abstract

Flake graphite (FG) was treated by microwave radiation in hydrogen peroxide solution and used to support stearic acid (SA) to synthesize SA/FG composites for thermal energy storage. The thermostability of the SA/FG was measured via TG-DSC, revealing they have good thermal stability up to 230 °C. The thermal properties of the composites were changed by varying the radiation time, and the SA/FG3 composite with the longest FG treatment time showed a higher latent heat value (61.05 J g-1 for melting and 61.00 J g-1 for freezing), and greater crystallinity (Fc, 98.34%) than other samples according to the analysis of DSC. The SA/FG3 composite had a good thermal reliability after thermal cycling tests. The thermal conductivity of SA/FG3 (3.18 W m-1 k-1) was 12.2 times higher than that of pure SA. Furthermore, the mechanism of the enhanced performance of SA/FG3 was further revealed by monitoring functional groups of the surface of FG and demonstrated on the atomic-scale. Infrared imaging showed SA/FG3 possessed superior thermal-regulated properties. Therefore, all these thermal properties indicate SA/FG3 has potential for application in thermal energy storage systems.