Abstract
The wetting behavior and affinity to side reactions of carbon‐based electrodes in vanadium redox flow batteries (VRFBs) are highly dependent on the physical and chemical surface structures of the material, as well as on the cell design itself. To investigate these properties, a new cell design was proposed to facilitate synchrotron X‐ray imaging. Three different flow geometries were studied to understand the impact on the flow dynamics, and the formation of hydrogen bubbles. By electrolyte injection experiments, it was shown that the maximum saturation of carbon felt was achieved by a flat flow field after the first injection and by a serpentine flow field after continuous flow. Furthermore, the average saturation of the carbon felt was correlated to the cyclic voltammetry current response, and the hydrogen gas evolution was visualized in 3D by X‐ray tomography. The capabilities of this cell design and experiments were outlined, which are essential for the evaluation and optimization of cell components of VRFBs.
Highlights
Solar, wind, and hydropower plants as so-called green energy sources are naturally subject to fluctuating power output, resulting in the demand for energy conversion and storage systems
We performed X-ray radiography and tomography experiments based on a novel beamline half-cell measurement setup, designed for visualizing the electrolyte flow in vanadium redox flow batteries (VRFBs) electrodes
We introduced a vanadium redox flow battery (VRFB) cell design for synchrotron X-ray radiography and tomography to visualize the injection behavior of the vanadium electrolyte through carbon felt materials
Summary
Wind, and hydropower plants as so-called green energy sources are naturally subject to fluctuating power output, resulting in the demand for energy conversion and storage systems. We present a novel vanadium redox flow cell design and the experimental procedures to further investigate the impact of carbon felt wetting behavior and flow field design on the performance and hydrogen evolution behavior of the VRFB under potential control. This cell was developed to utilize the visualization techniques at X-ray synchrotron facilities, such as radiography and tomography. The field of view is large enough to obtain technical relevant values and small enough to capture specific details such as gas bubbles growth
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