Strongly coupled calcium carbonate/antioxidative graphite nanosheets composites with high cycling stability for thermochemical energy storage. (1st December 2018)

• Record Type: Journal Article
• Authors: Han, Rui; Gao, Jihui; Wei, Siyu; Su, Yanlin; Sun, Fei; Zhao, Guangbo; Qin, Yukun
• Is Part Of: Applied energy. Volume 231(2018)
• Page Start: 412
• Page End: 422
• Publication Date: 2018-12-01
• Subjects: Concentrated solar power -- Thermochemical energy storage -- Calcium looping -- Graphite nanosheets; Power (Mechanics) -- Periodicals; Energy conservation -- Periodicals; Energy conversion -- Periodicals; 621.042
• DOI: 10.1016/j.apenergy.2018.09.142
• Languages: English
• ISSNs: 0306-2619

Abstract

Graphical abstract: Highlights: One-pot route was developed to synthesize CaCO3 /graphite nanosheets composites. H3 BO3 impregnation enhances the antioxidative ability of graphite nanosheets. CaCO3 /graphite nanosheets composites are highly efficient for heat energy storage. The composites show better heat storage performance than pure CaCO3 . Only 3 wt% of graphite nanosheets is required to stabilize the cyclic heat storage. Abstract: Reversible carbonation/calcination of CaCO3 is a promising technology for thermochemical energy storage in concentrated solar power plants. However, the major drawback of this technology is the rapid deactivation of CaO due to sintering. In this study, newly developed CaCO3 /graphite nanosheets composites were synthesized as the heat storage medium through a one-pot route varying the graphite nanosheets load (3–12 wt%). The impregnation of the composites with H3 BO3 solutions enhance the initial weightlessness temperature of graphite nanosheets from 900 °C to 1050 °C in pure CO2 atmosphere, thus upgrading the stability of graphite nanosheets during heat storage/release process. The performances of the synthesized composites were evaluated by thermogravimetric analysis, which simulates the heat storage cycle. The composites showed improved heat storage/output capacity and faster heat input/output rate compared to pure CaCO3 . Only 3 wt% of graphite nanosheets was needed to effectively stabilize the heat storage capacity of the material. The heat storage capacity of composites with 3 wt% graphite nanosheets is 1313 kJ/kgcomposite after 50 cycles, corresponding to 2.9 times as much as that of pure CaCO3 . This high stability is attributed to the unique synthetic strategy in which the CaCO3 nanoparticles uniformly coated on graphite nanosheets surface, and their sintering and aggregation were prevented. This work brings the development of this technology to a level closer to its industrial application.