Flow batteries based on organic redox-systems for large-scale electric energy storage

Abstract

Redox flow battery technology has been known since the 1970s. Their low specific characteristics have been of interest for a long time. Practical interest has arisen in recent decades because of the intensive development of alternative energy (such as solar and wind) and the regulation of peak loads in industrial networks. It turned out that large-scale energy storage systems used for compensation of fluctuations in the generation of energy by the sun and the wind, while producing electric vehicles and power supply systems for large households, are more profitable when they work on flow redox batteries. Firstly, they are easily scalable, and secondly, the energy stored in such batteries is cheap. Since the expansion of the scope of practical use of flow batteries has taken place in recent years, researchers continue to work on increasing the economic efficiency of flow batteries and on the search for more efficient redox systems. One of these areas is the use of cheaper redox systems of organic nature, in particular, quinone, anthraquinone and their analogs. Their high water solubility, well-separated oxidation-reduction potentials, which practically eliminate water splitting, their stability, safety, and low cost on a scale of mass production are the most important characteristics for new aqueous organic electrolytes. So far, organic redox flow batteries are still inferior to vanadium and other inorganic redox batteries in terms of their operational parameters. This drawback hinders their development on industrial scale. However, the results shown in this review can help scientists to improve them and commercialize in the future.

Keywords

• redox flow batteries
• inorganic redox systems
• organic redox systems
• quinones
• anthraquinones
• alizarin