Development of vanadium ion redox capacitor

Abstract

The purpose of this study was to add the redox capacitance obtained by adding vanadium ions used in the vanadium redox flow battery to the electric double layer capacitance. CV measurement confirmed a square response characteristic of the electric double layer and a redox peak of vanadium. In EIS measurement, the characteristics as a capacitor when vanadium was added were investigated. The performance as a power storage device was measured during constant current charging and discharging, and it was found that a maximum improvement of 39% in discharge energy density was found compared to blank. However, it was confirmed that the redox capacitance addition in discharging was smaller in CV and CDC than that in charging. This irreversibility was attributed to the activated carbon fiber electrode. For comparison, ACF and CF with different internal and surface structures were compared to clarify the mechanism.