Iron-based aqueous redox flow batteries (IBA-RFBs) represent a promising solution for long-duration energy storage, supporting the integration of intermittent renewable energy into the grid, thanks to their commendable safety profile and cost-effectiveness. Membranes, serving as pivotal components in redox flow batteries (RFBs), play a crucial role in facilitating ion conduction for internal circuit formation while preventing the crossover of redox-active species. Given their direct impact on RFB performance and cost, membranes merit considerable attention. This review provides an overview of recent advancements in membranes tailored for IBA-RFBs. Initially, it delineates the operational mechanisms of various IBA-RFB configurations. Subsequently, it delves into key performance metrics for evaluating membrane efficacy, dissecting the intricate interplay between membrane performance and overall IBA-RFB efficiency. Building upon this foundation, the review spotlights recent breakthroughs in ion exchange membranes and porous membranes designed specifically for IBA-RFBs, showcasing their remarkable ability to bolster battery efficiency, cycling stability, and cost-effectiveness. Lastly, this review outlines future directions for membrane development, offering some insights to propel the widespread adoption of IBA-RFBs on a large scale.

Aqueous zinc ion batteries (AZIBs), renowned for their high theoretical energy density, safety, cost-effectiveness and eco-friendliness, offer immense potential in the realm of energy storage and conversion, finding applications in renewable energy and portable devices. However, the development of AZIBs still faces several challenges related to the electrochemical behavior of zinc anodes in aqueous electrolytes, primarily zinc dendrite formation, which emphasize the critical need for a fundamental understanding of the interfacial phenomena between the electrode and electrolyte. This review focuses on the three models: the electric double layer (EDL) model, the solvation structure model, and the Zn/electrolyte interface model. They guide the design of the electrolyte system in AZIBs. These models provide a comprehensive understanding of the interactions between the electrode, electrolyte, and the solvated ions in the system. By optimizing the salt types, salt concentrations, solvents and additives based on these models, it is possible to enhance the performance of AZIBs, including their energy density, cycle life, and safety. The review also highlights recent research progress in electrolyte modification of AZIBs for understanding battery behavior, along with perspectives for the direction of further investigations.