Carbon Felts Electrode Treated in Different Weak Acid Solutions through Electrochemical Oxidation Method for All Vanadium Redox Flow Battery

Abstract

Electrochemical oxidation method in different weak acid (citric acid, oxalic acid and ethylene diamine tetraacetic acid) solutions was used to modify the carbon felts (CFs) electrode for all vanadium redox flow battery (VRFB). The CFs electrode was investigated through scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetric (CV) and linear sweep voltammetry (LSV). The electrochemical activity of the CFs was improved with little morphologies changing after it was treated in the weak solutions. Single cell was assembled to test the battery performances and the energy efficiency (EE) increases from 81.4% to 85.4% after the CFs was oxidized in ethylene diamine tetraacetic acid for 2 h. The enhanced electrochemical activity was ascribed to the increase of oxygen content on the surface of the treated CFs. The treated CFs are supposed to be used in the VRFB and improve the storage efficiency.