Redox flow batteries (RFBs) have gained intensive attention and are regarded as the ideal choice for large-scale energy storage owing to their attractive features such as excellent electrochemical reversibility, long life, high efficiency, and decoupling of energy and power density. Ion-exchange membranes in the flow battery act as a physical barrier to separate the positive and negative half-cell and allow migration of charge-balancing ions from one side to the other to complete the internal circuit of the cell. Certainly, the overall performance of the RFBs heavily depends on the properties of the ion-exchange membranes. To prevent power loss and minimize the crossover of the active species, it is essential for the ion-selective membrane to acquire high ionic conductivity to ensure low area specific resistance and high selectivity. This review summarizes recent research advances on improvement methods to enhance the selectivity of membranes in RFBs, mainly including the modifications on the pore size, hydrophilicity, and some other aspects. The relationship between performances and structures of these membranes is analyzed, and the advantages and limitations are discussed. Based on the recent advances, corresponding perspectives on future development in this field are also discussed.

氧化还原液流电池（RFB）受到广泛关注，并因其诱人的特性（例如出色的电化学可逆性，长寿命，高效率以及能量和功率密度的解耦）而被视为大规模储能的理想选择。液流电池中的离子交换膜可作为物理屏障，将正半电池和负半电池分开，并允许电荷平衡离子从一侧迁移到另一侧，从而完成电池的内部电路。当然，RFB的整体性能在很大程度上取决于离子交换膜的特性。为了防止功率损耗并使活性物质的交叉最小化，离子选择膜必须具有高离子电导率以确保低面积比电阻和高选择性。这篇综述总结了提高RFB中膜选择性的改进方法的最新研究进展，主要包括对孔径，亲水性和其他一些方面的修改。分析了这些膜的性能与结构之间的关系，并讨论了其优缺点。基于最新进展，还讨论了该领域未来发展的相应观点。