Deploying redox flow batteries (RFBs) at system-level is more expensive than low-cost metal-ion alternatives. Not only this, but RFBs’ energy density is significantly lower than that of a metal-ion battery. Both factors in combination mean investors see RFBs as high risk.
However, according to the authors of the new study “A critical review on the recent progress of vanadium redox flow battery materials for electrolytes, membranes and electrodes preparation,”published in the Journal of Power Sources, the technology can have advantages over the more common lithium-ion, and this is particularly evident when expanding storage to grid-scale.
“The future holds bright in the domain of redox flow batteries,” Yansong Zhao, professor at Western Norway University of Applied Sciences and corresponding author of the study, told pv magazine.
“RFBs showcase their advantage in the grid-scale stationary energy storage application rather than electric vehicles (EVs) or small-scale devices,” explained Zhao, noting that educating investors on the advantages of RFBs “can eradicate the risk element.”
“RFBs offer safety, reliability, and scalability while demonstrating energy efficient performance for more than 10,000 cycles of operation,” he said, adding that on the downside RFBs require “an immensely high initial capital investment” and have “low energy density, low operating potentials, volatile material procurement costs, a lack of standardization and awareness as compared to traditional and well-developed and researched lithium-ion batteries.”
He observed that RFBs’ suitability for scaling in grid-scale scenarios could potentially compensate for their low energy density relative to metal-ion batteries.
In its critical review, the paper looked at the impact of different electrolytes and membranes on the performance of RFBs. It also explored modifications to electrodes aimed at enhancing redox kinetics.
“Although several reviews have been published on vanadium RFBs, most focus on individual aspects such as electrolyte chemistry, membrane development, or electrode activation. In contrast, this review provides an integrated summary of recent progress across all three critical components, with a particular emphasis on work published in the last two to three years. By systematically addressing these aspects of RFBs, researchers aim to overcome existing limitations and unlock the full potential of this promising energy storage technology for a wide range of applications, from grid-scale energy storage to EVs and beyond,” the paper stated.
Zhao said that price volatility associated with the redox active material plus high ion-exchange membrane costs can account for more than half of the total RFB cost and this is one of the main factors hindering large-scale commercialization.
He added that further research in incorporating alternative redox active materials which showcase cost effectiveness while demonstrating competitive performance can aid in the direction of replacing vanadium. He also suggested titanium as a potential replacement for the anolyte solution, noting its abundance and relatively competitive performance and low material procurement cost.
He told pv magazine that in a stationary, grid-scale storage context, the volume of liquid electrolytes in RFBs can be scaled in accordance with system requirements. He added that research is underway into numerous component combinations of electrolytes that could improve the energy density. Work is also ongoing on advancing membranes and exploring solvent alternatives to water.
Based on their critical review of the literature and approaches taken by others, the paper’s authors recommended that future research should prioritize optimizing various material combinations to improve system performance, making them more viable for large-scale energy storage applications in the future.
This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com.
By submitting this form you agree to pv magazine using your data for the purposes of publishing your comment.
Your personal data will only be disclosed or otherwise transmitted to third parties for the purposes of spam filtering or if this is necessary for technical maintenance of the website. Any other transfer to third parties will not take place unless this is justified on the basis of applicable data protection regulations or if pv magazine is legally obliged to do so.
You may revoke this consent at any time with effect for the future, in which case your personal data will be deleted immediately. Otherwise, your data will be deleted if pv magazine has processed your request or the purpose of data storage is fulfilled.
Further information on data privacy can be found in our Data Protection Policy.