2025 AIChE Annual Meeting

Electrodeposition of Bismuth on a Copper Anode in a Vfrb

In the current technology for Vanadium Redox Flow batteries (VFRB), maximizing coulombic efficiency, volumetric flow power, and current densities are of the highest concerns. Many configurations for the design of the battery have been proposed, each with their own advantages and disadvantages, and with the tubular geometry of our battery, however, comes undesirable high ohmic resistance. The use of copper as the anode material, instead of the conventional graphite, was proposed as the solution as it promotes the necessary V2/V3 reaction and is very conductive; however, copper is kinetically very active towards the Hydrogen Evolution Reaction (HER). To prevent this side reaction while also maintaining the high conductivity of copper, the use of Bismuth, due to its inherent suppression of the HER, was explored. Different concentrations of Bismuth Chloride (.001 M, .005M, .01, .05 M, and .1M) were dissolved in a solution of 4.25M sulfuric acid. Each of those solutions were then used as basis solutions for Bismuth electrodeposition onto 1.6mm diameter copper wires. The coated copper wires were then subject to Linear Sweep Voltammetry (LSV) to assess the new anode’s propensity to the HER. Cyclic voltammetry tests were conducted on the wires to assess the overall stability and improvements towards the HER side reactions. Finally, the Bismuth coated copper anodes were cycled to assess the coulombic efficiency. The end results showed a drastic decrease in HER with the .1M solution having the greatest reduction from the LSV testing. The morphology of the .001M and .1M differed in the uniformity of the plating; the higher concentration solution yielded a very even plating with some shards of Bismuth forming while conversely, the .001M solution yielded localized Bismuth plating in very fine, small particles. Bismuth electroplated copper wires show promise as a graphite alternative for the anode material in VFRBs demonstrating excellent stability in the harsh acidic environment, conductivity, and reduction in the HER.