Neutron Imaging Reveals Iron Plating Dynamics in Redox Flow Batteries

A team of researchers from TU/e, in collaboration with the Paul Scherrer Institute in Switzerland, has employed neutron imaging to gain unprecedented insight into the internal processes of all-iron redox flow batteries (AIRFBs). This innovative technique allowed them to visualize the movement of metallic iron and track the formation of solid, gas, and liquid iron phases within the battery in real time during operation.

All-iron redox flow batteries are a promising renewable energy storage solution due to the abundance, low cost, and safety of iron. However, their performance is significantly impacted by how iron deposits on the negative electrode during charging and discharging cycles. Ideally, these deposits should be uniform, but this is not always achieved, leading to reduced battery lifespan.

The study, published in Nature Communications, revealed that uniform iron plating on the negative electrode occurs when the electrolyte flow is purely convective. In contrast, when the electrolyte flow is a mixture of convective and random movement, nonuniform deposits are formed. This finding directly links the electrolyte flow behavior to the efficiency and durability of the battery.

By using neutron radiography, which allows neutrons to penetrate the battery casing and interact with the iron ions, the researchers could observe phenomena that traditional battery analysis methods often miss. These detailed observations are expected to guide the design and optimization of future AIRFB systems, potentially overcoming limitations that have previously hindered their widespread adoption.