The intermittent nature of many renewable energy technologies, including solar and wind, require grid-scale energy storage systems to meet on-demand energy needs. Redox flow batteries have emerged as a promising technology with the potential to address these needs. One critical component of a redox flow battery is the membrane, which physically separates the electrolytes in each half cell while allowing for charge carrier transport. However, membranes still present a significant challenge for large-scale adoption of redox flow batteries. Commercially available membranes can be expensive, have only modest ion selectivity, and/or lack chemical stability in the strong oxidizing and reducing environments experienced during battery operation.<br/><br/>Here, we focus on the synthesis of an inorganic porous membrane for redox flow applications. Specifically, the membrane is based on silica, which shows the significant advantages of high chemical stability and extremely low cost. Using a simple sol-gel process, we can control the nanoscale pore structure and surface chemistry of the silica membrane. For example, by adjusting the gelation conditions, the average pore radius can be significantly decreased. For redox flow systems based on vanadium, our membranes have demonstrated excellent ion selectivity based on both size and charge exclusion, allowing proton transport but hindering electrolyte crossover. The flexibility of the sol-gel process also allows us to tailor the membrane properties for a variety of other systems, including redox flow batteries based on non-aqueous electrolytes and water treatment through electrodialysis.

Nanoporous ceramic membranes for redox flow batteries

2019 Fall National Meeting

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