Enhancement of electrochemical behavior with additives for vanadium redox flow battery electrolyte

Abstract

The electrolyte is the key component in vanadium redox flow batteries (V-RFB), serving both as an ion-conducting medium to complete the electrical circuit and as a storage for energy in its chemical form. The electrolyte's concentration directly affects the battery's storage capacity. Typically, the electrolyte in a V-RFB consists of a vanadium-based mixture in various oxidation states, combined with supporting solvents like hydrochloric (HCl) and sulfuric (H₂SO₄) acids. To enhance these batteries' performance, improving the electrolyte's properties is essential, particularly to sustain charge/discharge cycles over time. This research assessed the impact of various organic additives on the electrolyte's performance in V-RFBs. Techniques like cyclic voltammetry (CV) and charge-discharge testing were employed to study their electrochemical effects. The findings indicate that these additives enhance the redox reaction's reversibility, diminish the potential drop during charging and discharging, and amplify the peaks of oxidation and reduction signals. In tests, the V-RFBs, when augmented with suitable additives, demonstrated stable operation with a charge-discharge efficiency exceeding 75%.