The current electrical power grid cannot stabilize fluctuations, which results in inefficiencies and inabilities to integrate intermittent renewable energy supplies, such as solar and wind, into the grid. To address this problem, the Department of Energy has supported the development of flow batteries, which are large stationary energy storage devises that buffer fluctuations. Flow batteries differ from conventional batteries in that charge is stored in redox-active compounds dissolved in an electrolyte (kept in tanks), instead of at electrodes. Presently, flow battery costs and performance metrics (i.e., charge storage densities and charging rates) are inadequate for widespread use. Here, we tested if flow battery charge storage densities could be increased using hydrotropes, a class of organic chemicals that substantially increase the solubilities of redox-active organic molecules without inhibiting their reactivities. Hydrotropes differ from surfactants and co-solvents in that they can solubilize organic compounds via specific molecular orientation interactions. To date, the underlying mechanisms by which hydrotropes solubilize organic compounds remains a controversial topic in the literature. Here, we report on the extent to which four commonly used hydrotropes increased the solubilities of five organic redox-active compounds previously used in flow battery studies.

Utilizing hydrotropes to increase flow battery storage densities

2019 Spring National Meeting

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