Ultrathin graphite sheets stabilized stearic acid as a composite phase change material for thermal energy storage. (1st January 2019)

• Record Type: Journal Article
• Authors: Li, Chuanchang; Xie, Baoshan; Chen, Deliang; Chen, Jian; Li, Wei; Chen, Zhongsheng; Gibb, Stuart W.; Long, Yi
• Is Part Of: Energy. Volume 166(2019)
• Page Start: 246
• Page End: 255
• Publication Date: 2019-01-01
• Subjects: Ultrathin graphite sheets -- Stearic acid -- Phase-change materials -- Thermal energy storage -- Coupled ultrasonication-milling -- Shear-assisted supercritical CO2; Power resources -- Periodicals; Power (Mechanics) -- Periodicals; Energy consumption -- Periodicals; 333.7905
• DOI: 10.1016/j.energy.2018.10.082
• Languages: English
• ISSNs: 0360-5442

Abstract

Abstract: 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. Highlights: Ultrathin graphite sheets were used as supports to prepare form-stable PCMs. Supports were stripped through ultrasonication-milling and shear-assisted supercritical CO2 stripping. Different stripping levels affect performances of corresponding composite PCMs. The composite has remarkable latent heat for thermal energy storage.