The Correlation Between Charge and Discharge Current for the Electrochemical Stability and Durability of Electrolyte in a Vanadium Redox Flow Battery

摘要

The object of this paper is to simulate electrochemical performances of V‐electrolyte employed in the VRFB cell when different charge/discharge current densities are given. Experimental results show that increasing charge(or discharge) current for a given discharge (or charge) current leads to the reduction of both voltaic efficiency and charge(or discharge) capacity as compared to the use of same charge/discharge currents, while resulting in coulombic efficiency improvement. In contrast, the decreasing cases provide the improvement of both the voltaic efficiency and the capacity, but there takes place a serious problem of the capacity fading effect as well as the coulombic efficiency reduction. This is because low charge/discharge current densities causes polarization effects and self‐discharges during cyclic operation, resulting in electrochemical instability of electrolyte performance. Consequently, both the charge and discharge current densities have to be employed over 80 mA/cm2 to keep an electrochemical stability of electrolyte.