Polymer Electrolyte Membranes for Vanadium Redox Flow Batteries: Fundamentals and Applications

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. Al-though 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 mech-anisms, 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. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Electrochemical energy storage systems, particularly flow batteries, are seen as promising solutions for large-scale utilization of renewable energy due to their flexible design, high efficiency, long lifespan, and adjustable power and energy storage capacity. However, challenges such as the high cost of materials hinder the broad adoption of flow battery technology. Polymer electrolyte membranes play a crucial role in flow batteries by providing charge carriers transport pathways and preventing electrolyte crossover, but their cost impacts the overall financial feasibility of the battery system.