(532e) Redox Flow Batteries with a Double Ion-Exchange Membrane Design

Redox flow batteries are considered the most promising technology for large scale electrical energy storage. Different from the conventional single membrane configuration, we have developed a new double-membrane triple-electrolyte concept that offers unprecedented freedom in choosing the redox pairs with different charges and the pHs of the electrolytes [1-3].  Specifically, the double-membrane cell with one cation-exchange membrane (CEM), one anion-exchange membrane (AEM), and a middle electrolyte in between can incorporate an anion redox pair and cation redox pair, markedly expanding the range of chemistries usable in flow batteries. Among various possible combinations, we have demonstrated three examples: 1) Zn-Ce flow battery that offers a 3.1 V cell voltage, the highest for an aqueous flow battery; 2) S-Fe flow battery that is very inexpensive because S and Fe are the 5^th and 1^st most produced element, respectively; 3) Zn-Fe flow battery that has a high cell voltage (1.99 V), high performance (647 mW/cm²peak power density), and low overall cost (less than $100/kWh). 

[1] Shuang Gu,   Ke Gong,   Emily Z. Yan and   Yushan Yan, A multiple ion-exchange membrane design for redox flow batteries, Energy Environ. Sci., 2014, DOI: 10.1039/C4EE00165F

[2] Y.S. Yan, S. Gu, K. Gong, Double-membrane triple-electrolyte redox flow battery design, Application No.: 13/918444, Publication date: 01/02/2014

[3] Y.S. Yan, S. Gu, K. Gong, Multiple-membrane multiple-electrolyte redox flow battery design,  Application No.: 13/918452, Publication date: 01/02/2014