An all-extruded tubular vanadium redox flow cell - Characterization and model-based evaluation

The vanadium redox flow battery (VRFB) as one of the most promising electrochemical storage systems for stationary applications still needs further cost reductions. Tubular cell designs might reduce production costs by extrusion production of cell components and small sealing lengths. Based on a first study of the authors [1], this work demonstrates the feasibility of extruded tubular VRFB cells with high power density in the flow-by electrode configuration. Extruded cell components are the perfluorosulfonic acid cation exchange membrane with a diameter of 5.0 mm and carbon composite current collectors. The cell performance is experimentally characterized by polarization curve, ohmic resistance and galvanostatic cycling measurements. A maximum volumetric power density of 407 kW/m³ and a maximum current density of 500 mA/cm² can be achieved. A non linear E_cell/i-model is used to evaluate exchange and limiting current densities while in-situ half cell SoC monitoring is applied to evaluate the extruded membrane.