Ultrathin graphite sheets (UGSs) were stripped directly from natural flake graphite (FG) through a coupled ultrasonication-milling (CUM) process followed by a shear-assisted supercritical CO2 (SSC) stripping. As-prepared UGSs were centrifuged (3500 and 5000 rpm) to support stearic acid (SA) to produce SA/UGSs. Characterization results proved UGSs was stripped from natural FG. Structural and morphological characterization demonstrated that the UGS-5000 had a layer thickness was about 3.4–4.2 nm, significantly thinner than that of natural FG. Raman spectra and TG-DSC analysis showed UGS-5000 have more structural defects than other UGSs, and could accommodate a SA loading capability of 171.5%. FTIR and XRD analysis indicated that no chemical reaction had occurred between SA and UGSs during impregnation. All samples had a good thermal stability below 180 °C, with the endothermic phase change peak being recorded between 53.60 and 53.12 °C range, and the melting and freezing enthalpies of SA/UGS-5000 were 113.7 and 112.9 J g−1, respectively. After 50 thermal cycles, it could keep a great thermal reliability and has a thermal conductivity of 10.08 times higher than that of pure SA. These results demonstrate that SA/UGS-5000 have potential in thermal energy storage applications including cooling, building energy efficiency and solar thermal storage.
Li, C., Xie, B., Chen, D., Chen, J., Li, W., Chen, Z., Gibb, S. W., & Long, Y. (2019). Ultrathin graphite sheets stabilized stearic acid as a composite phase change material for thermal energy storage. Energy Procedia, 166, 246-255. https://doi.org/10.1016/j.energy.2018.10.082