Acid-Base Blend Membranes for Redox Flow Batteries

Redox flow batteries (RFBs) have the potential for economical storage of electrical energy than other battery chemistries. They use high-cost ion exchange membranes as separators between anolyte and catholyte, which prevent broad market penetration. Proton exchange membranes (e.g., Nafion) are poorly selective, allowing undesired cross-diffusion of active species in solution electrolytes across the membranes and reducing the efficiency and durability of RFBs. Lynntech in collaboration with University of Texas at Austin (UT) and University of Texas at Arlington (UTA) propose to develop a low-cost, high proton conductivity, and ultralow permeability acid-base blend membrane which can enable the development of cost-effective and high performance RFBs than current technologies. The innovative acid-base blend membrane allows rapid proton transport but ultralow diffusion of water and active species. The development of the blend membrane will provide redox flow batteries with improved efficiency, and significantly improved durability and operating lifetimes. During the Phase I, UT will synthesize and prepare the blend membrane; Lynntech will determine the membranes proton conductivity and permeability of vanadium ions, and evaluate the membranes electrochemical performance in an all-vanadium redox flow battery (V-RFB); UTA will study the synergistic effects of the membrane properties on dynamics of V-RFBs, with focus on both coulombic and voltage efficiencies, as well as providing general guidance to the proposed membrane material development. During the Phase II, the blend membrane will be optimized and be applied in an all-vanadium flow battery stack, and a low-cost large-scale membrane production process will be developed. The proposed low-cost and highly selective proton-conducting blend membrane can enable the development of cost-effective and high performance redox flow batteries. The technology has the potential to develop low-cost and durable stationary power systems, which can change the way in which electrical energy is generated, distributed, and used. Potential applications including remote power systems matching power generator outputs and fluctuating loads from renewable energy sources such as solar and wind, and power management systems for smart grid and residential applications