Electrochemical energy storage systems are considered as one of the most viable solutions to realize large-scale utilization of renewable energy. Among the various electrochemical energy storage systems, flow batteries have increasingly attracted global attention due to their flexible structural design, high efficiencies, long operating life cycle, and independently tunable power and energy storage capacity. Although promising, a number of challenges including the high cost of flow battery materials hinder the broad market penetration of flow battery technology. Polymer electrolyte membrane, as a key component in flow batteries providing pathways for charge carriers transport and preventing electrolytes crossover, takes over 25% of the entire cost of the battery system. Apparently, the membrane not only plays pivotal roles in the operation characteristics of a flow battery, but also largely influences the financial cost of the battery system. To provide insights and better understanding of membranes towards enhancing their performance and cost-effectiveness, we therefore present recent advances and research outcomes on the development of polymer electrolyte membranes as well as their applications in flow batteries, particularly all-vanadium redox flow batteries. Various aspects of polymer electrolyte membranes including functional requirements, characterization methods, materials screening and preparation strategies, transport mechanisms, and commercialization progress are presented. Finally, perspectives for future trends on research and development of polymer electrolyte membranes with relevance to flow batteries are highlighted.

电化学储能系统被认为是实现大规模利用可再生能源的最可行解决方案之一。在各种电化学储能系统中，液流电池因其灵活的结构设计，高效率，较长的使用寿命以及可独立调节的功率和储能能力而日益引起全球关注。尽管前景广阔，但液流电池材料的高成本等诸多挑战阻碍了液流电池技术在市场上的广泛普及。聚合物电解质膜作为液流电池的关键组件，为电荷载流子的传输提供了途径，并防止了电解质的渗透，占据了整个电池系统成本的25％以上。显然，膜不仅在液流电池的运行特性中起着关键作用，而且在很大程度上影响电池系统的财务成本。为了提供对膜的见解和更好的理解，以提高其性能和成本效益，因此，我们介绍了聚合物电解质膜的开发及其在液流电池，特别是全钒氧化还原液流电池中的应用的最新进展和研究成果。介绍了聚合物电解质膜的各个方面，包括功能要求，表征方法，材料筛选和制备策略，运输机理以及商业化进展。最后，