• Critically analyses the ion transport mechanisms of various membranes and compares them, highlighting the challenges for vanadium redox flow battery (VRFB) applications.
• Provides in-depth analysis and discussion of the best strategies for membranes to achieve high-performance VRFBs.
• Prospective approaches to realising high-performance, sustainable VRFB membranes are outlined.
• Emphasizes the trade-off between membrane efficiency and durability, and the need for cost-effective solutions.