Integrated design of hematite and dye-sensitized solar cell for unbiased solar charging of an organic-inorganic redox flow battery. (August 2019)

• Record Type: Journal Article
• Authors: Khataee, Amirreza; Azevedo, João; Dias, Paula; Ivanou, Dzmitry; Dražević, Emil; Bentien, Anders; Mendes, Adélio
• Is Part Of: Nano energy. Volume 62(2019)
• Page Start: 832
• Page End: 843
• Publication Date: 2019-08
• Subjects: Solar redox flow cell -- Hematite -- Tandem system -- Anthraquinone -- Dye-synthesized solar cell; Nanoscience -- Periodicals; Nanotechnology -- Periodicals; Nanostructured materials -- Periodicals; Power resources -- Technological innovations -- Periodicals; Nanoscience; Nanostructured materials; Nanotechnology; Power resources -- Technological innovations; Periodicals; 621.042
• DOI: 10.1016/j.nanoen.2019.06.001
• Languages: English
• ISSNs: 2211-2855

Abstract

Abstract: Integration of the photoelectrochemical cells and redox flow batteries (RFBs) is conceptualized as solar redox flow cells (SRFCs). The SRFC opens an opportunity for simultaneous electrochemical conversion and storage of solar energy in a single device. This work proposes a SRFC which integrates stable hematite (α-Fe2 O3 ) photoanode with a near-neutral organic-inorganic RFB using organic and low-cost redox pair anthraquinone-2, 7-disulfonate disodium (AQDS) on the negative side and iodide/iodine ( I − / I 2 ) redox couple on the positive side. The AQDS/iodide RFB exhibited a stable battery cycling with a cell voltage of ~0.8 V, a high coulombic efficiency of 99.2% and a peak power density of 0.22 W⋅cm −2 . The hematite yielded a stable performance in contact with iodide/iodine solution with pH 5.5, despite known stability issues for pH < 7. Electrochemical impedance spectroscopy was used to elucidate the main semiconductor/electrolyte charge transfer mechanisms and rates and energy level alignment of hematite with redox pair voltages. Finally, to photocharge the AQDS/iodide SRFC unbiasedly, a tandem system was used which includes hematite photoelectrode connected in series with a dye-sensitized solar cell (DSSC). The tandem photoelectrode provided 1.6 V of photovoltage that is sufficient to fully charge the RFB. Graphical abstract: Image 1 Highlights: Unbiased solar charging of quinone-iodide redox flow battery is presented using a tandem system. Tandem system is made up of hematite in series with a dye-sensitized solar cell, provides 1.6 V photovoltage. Unlike the stability issues of hematite at pH < 7, it shows stable performance with iodide/iodine solution at pH 5.5. Quinone-iodide redox flow battery exhibits average current and energy efficiencies of 99.2% and 76%, respectively.