(194f) Double Membrane Redox Flow Batteries for Economical and Efficient Renewable Electricity Storage

Redox flow batteries (RFBs) are considered as the most promising technology for economical and scalable electricity storage for wind and solar energy. By decoupling the energy storage and the power delivery from each other, RFBs hold a level of design flexibility and system scalability unavailable to traditional rechargeable batteries. Since their invention, RFBs have stayed with single ion-exchange membrane (single-IEM) configuration that cannot effectively use redox pairs with mixed charges and/or supporting electrolytes with different pHs. In this work, we show a universal design concept based on a double-IEM configuration that brings unprecedented freedom in choosing both redox pairs and supporting electrolytes. Two aqueous RFB examples are featured: (1) ultra-high voltage zinc-cerium RFB with a standard cell voltage of 3.08 V, the highest among all known aqueous RFBs; and (2) ultra-low cost sulfur-iron RFB with a standard cell voltage of 1.22 V, based on two highly available electroactive elements (iron and sulfur being the 1st and 5th most produced elements worldwide, respectively). The double-IEM concept is general and can be applied to non-aqueous RFBs.