Researchers used neutron imaging to observe iron deposition in redox flow batteries, revealing performance-limiting behaviour that could improve future battery efficiency, durability and scalability.
Eindhoven University of Technology, working with Switzerland’s Paul Scherrer Institute, has demonstrated how neutron imaging can reveal the internal behaviour of all-iron redox flow batteries in real time. The research, published in Nature Communications, offers fresh insights into how iron deposits form during charging and discharging, paving the way for improved battery performance and longer operational lifetimes.
All-iron redox flow batteries are considered a promising option for large-scale renewable energy storage because they use iron, an abundant, low-cost and safe material. However, their performance depends heavily on how iron is deposited on the battery’s negative electrode. While a uniform iron layer is ideal, researchers found that deposition often becomes uneven, reducing efficiency and shortening battery life.
To investigate this challenge, the team employed neutron radiography to visualise the movement of iron ions inside an operating battery. Unlike conventional diagnostic techniques, neutron imaging can penetrate the battery casing while interacting with iron ions in the electrolyte, allowing researchers to observe the formation of solid, liquid and gaseous phases as they occur.
The images showed that iron deposits remain evenly distributed only when electrolyte flow is purely convective. When the flow becomes a combination of convective and random motion, non-uniform plating develops on the electrode surface. According to the researchers, this uneven deposition is a major factor influencing battery performance and long-term durability.
The findings identify key operating parameters that affect iron plating behaviour, providing valuable guidance for improving future battery designs. By enabling engineers to optimise electrolyte flow and deposition patterns, the research could support the development of more reliable, efficient and cost-effective iron redox flow batteries for grid-scale renewable energy storage.
