Advances in the design and fabrication of high-performance flow battery electrodes for renewable energy storage

The redox flow battery is one of the most promising grid-scale energy storage technologies that has the potential to enable the widespread adoption of renewable energies such as wind and solar. To do so, the performance of redox flow batteries must be enhanced while the cost needs to be reduced. Electrodes are a key component where coupled electrochemical reactions and mass transport take place, and they play a critical role in determining the battery performance and system cost. This review summarizes recent developments in the design and fabrication of electrospun carbon fibers, which offers a bottom-up solution to the formation of electrodes with desired properties for high-performance flow batteries. The principles of electrospinning nanofibers and the key parameters that affect the morphologies of electrospun carbon fibers are discussed and summarized. The factors that influence electrode properties, including geometric structures, surface properties, electrical conductivity, mechanical strength, and wettability on the battery performances, are comprehensively elaborated with an emphasis on the electrode structure and surface properties that determine the mass transport and reaction kinetics. Finally, the scientific challenges and prospects of electrospun carbon fiber electrodes with maximized specific surface areas and hydraulic permeability are presented. This review offers insights into the design and development of advanced electrodes for next-generation flow batteries in the application of renewable energy storage.