Ion conductive membranes for flow batteries: Design and ions transport mechanism

Abstract Flow batteries are one of the most promising techniques for stationary energy storage applications, benefiting from their high safety, high efficiency and long cycle life. As a key component of flow batteries, an ion conductive membrane (ICM) plays a vital role in isolating active species from anolyte and catholyte, while transferring charge careers to complete the internal circuit. Therefore, the final battery performance is largely determined by the properties of ICMs such as ions selectivity, conductivity and stability. Thus, transport behavior of different ions through ICMs will be critical to design high-performance flow batteries. Plenty of membranes with different structures have been developed in flow batteries, however, the ions transport mechanism in different membranes was rarely summarized. In this review, a brief introduction on ICMs will be firstly given and then the ions transport mechanism in different membranes will be summarized in detail. This review is expected to provide important guidance for the design of membranes for flow batteries.