Pathways to Realize High-Energy Density Aqueous Redox Flow Batteries

Abstract

The transition to renewable energy is hindered by the intermittency of sources like solar and wind, necessitating advanced energy storage solutions. Aqueous redox flow batteries (ARFBs) have emerged as a promising technology for long-duration, grid-scale energy storage due to their advantages in safety, scalability, and independent tunability of power and energy capacities. Enhancing energy density is crucial for reducing system costs and facilitating large-scale deployment. In this review, key parameters and strategies for boosting the energy density of ARFBs are summarized, including optimizing material solubility and electron-transfer capabilities, developing novel redox pairs, and improving system design to reduce polarization losses. Despite significant progress, challenges remain—such as developing suitable materials, the optimal matching of electrodes, electrolytes, and membranes, and scaling systems for industrial applications. Advanced characterization tools, AI-driven simulations, and continued research on new materials and system engineering will be essential for overcoming these barriers. With ongoing innovation, ARFBs hold tremendous promise of substantially contributing to the integration of renewable energy.