Modeling an All-Copper Redox Flow Battery for Microgrid Applications: Impact of Current and Flow Rate on Capacity Fading and Deposition

The copper redox flow battery (CuRFB) stands out as a promising hybrid redox flow battery technology, offering significant advantages in electrolyte stability. Within the CuBER H-2020 project framework, this study addresses critical phenomena such as electrodeposition at the negative electrode during charging and copper crossover through the membrane, which influence capacity fading. A comprehensive two-dimensional physicochemical model of the CuRFB cell was developed using COMSOL Multiphysics, providing insights into the distribution of electroactive materials over time. The model was validated against experimental cycling data, demonstrating a Root Mean Square Error (RMSE) of 0.0212 in voltage estimation. Least-squares parameter estimation, utilizing Bound Optimization by Quadratic Approximation, was conducted to determine active material diffusivities and electron transfer coefficients. The results indicate that higher current densities and lower flow rates lead to increased copper deposition near the inlet, significantly impacting the battery’s State of Health (SoH). These findings highlight the importance of considering fluid dynamics and ion concentration distribution to improve battery performance and longevity. The study’s insights are crucial for optimizing and scaling up CuRFB operations, guiding potential cell-scale-up strategies into stack-level configurations.