1, Simon Fraser University, Vancouver, British Columbia, Canada
The cation-species crossover, cost, and persistent environmental toxicity of perfluorinated sulfonic acid membranes such as Nafion® significantly affect the capital, operational, and maintenance costs of many flow battery systems, as well as end-of-life costs and overall environmental impact. While these have remained a standard feature of flow-battery systems for many years due to a lack of mechanically and chemically stable alternatives.
Recently, research into alkaline anion exchange membrane fuel cells have significantly enhanced the conduction properties alongside both the chemical and mechanical stability of anion-exchange membranes. In particular, Zhang & coworkers recently demonstrated the viability of acid-doped PBIs for vanadium redox-flow battery systems in short-term tests. Zeis & coworkers similarly demonstrated the long-term oxidative stability of many variants.
Here, we report a PBI-family anion-exchange membrane suitable for several redox-flow battery chemistries, including all-vanadium systems. These materials are fully hydrocarbon and feature enhanced processability, consistency, and ability to block chemical crossover. We report on material development strategies that lead to these advanced properties, as well as physical and both ex situ and in situ electrochemical characterization performed to date. We further report on our attempts to define the impact of improved membrane materials on the levelized cost of energy storage (LCOS).
 X.L. Zhou, T.S. Zhao, L. An, L. Wei, & C. Zhang. Electrochim. Acta, 153, 2015. 492-498.
 F. Mack, K. Aniol, C. Ellwein, J. Kerres, & R. Zeis. J. Mat. Chem. A., 3, 2015. 10864-10874.