Structural modification of vanadium redox flow battery with high electrochemical corrosion resistance

Abstract

In the conventional vanadium redox flow battery, the bipolar plates are usually designed with flow fields to improve the battery performance by facilitating the homogeneous distribution of electrolytes. The introduction of flow field results in severer oxidation corrosion, owing to the sharp edges and corners formed on the flow fields. In this study, a modified battery structure for the vanadium redox flow battery is proposed to alleviate the oxidation corrosion of the bipolar plates and flow fields. The flow fields are segmented from the bipolar plates, and inserted between the porous electrodes and membrane as independent components. To improve the service life and processability, the flow fields are prepared with photosensitive resin by means of the three-dimensional printing technique. A battery with the modified structure is assembled to examine the battery performance and oxidation resistance. Morphology characterization and elemental composition analysis are employed to investigate the oxidization on the bipolar plate surface. The modified battery structure contributes to decreasing the contact resistance. The pressure drop and charging/discharging tests indicate that the battery with the modified structure exhibits maintained flow behavior and energy efficiency, and provides a higher Coulombic efficiency compared to the conventional vanadium redox flow battery. Moreover, the bipolar plates in the modified battery structure demonstrate a higher capacity to restrain oxidation corrosion during the charging process. The modified battery structure can enhance the service life of bipolar plates and flow fields, and is significant in the application of vanadium redox flow battery.