440675 Transport Properties of Separators for Redox-Flow Batteries in Aqueous Systems

Monday, November 9, 2015
Exhibit Hall 1 (Salt Palace Convention Center)
Jaime Rodriguez1, Liang Su2 and Fikile Brushett2, (1)Chemical Engineering, Florida Institute of Technology, Melbourne, FL, (2)Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA

Sources of renewable energy, such as solar and wind, have been proposed as a possible solution to our overwhelming dependence on fossil fuels.  Large-scale energy storage devices are of critical importance to realize the widespread installation of renewable energy systems.  In this regard, redox-flow batteries (RFBs) that reversibly convert electrical energy to chemical energy have shown to be a promising option for the grid-scale energy storage to smooth out the intermittency of renewables.  However, the successful integration of RFBs has been limited by their high cost, most notably contributed by the membrane.  The membrane plays a vital role in the performance, separating the electrolyte solutions while allowing ions to permeate to complete the redox reactions.  An ideal membrane should have a high ionic conductivity and low crossover of active species.  The primary goal of the research was to characterize the figure of merit of the commercially available battery separators in aqueous systems.  Specifically, both conductivity and crossover for a range of charge-selective membranes and size-selective separators were measured using a static, H-cell setup.  In addition, the crossover test was also carried out in a flow cell system to examine the impact of flow on the membrane performance.  The key outcome of this research was that a relationship between membrane conductivity and species crossover was established, which will provide critical information for the rational design of membranes for aqueous RFBs.

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