Modification Of Graphite Felt Electrode In Vanadium Redox Flow Battery

A vanadium redox flow battery possesses many advantages over conventional storage batteries. However, the development of vanadium redox flow battery is limited by three factors:electrode material, membrane and electrolytes.A satisfactory vanadium redox flow battery electrode material has the features as follows:1) favorable stability, mechanistic capability, acid resistance and strong oxidizing property of anti-quinque valence vanadium, which prolongs the life of batteries; 2) fine electrochemical activity to insure vanadium reaction and minimize insulation of hydrogen and oxygen; 3) good conductivity; 4) lower cost. Untill now, the graphite felt is used as electrode material for vanadium batteries at home and abroad. However, graphite felt is the hydrophobic, electrochemical activity is poor and electrode reaction reversible is not good. It is needed to choose a suitable method for surface modification of the electrode, so that the effective graphite felt surface area increased and -C-O,-C=O oxygen-containing functional groups in graphite felt surface also increased. Then the vanadium battery electrode reaction speed is improved, the transfer of vanadium ions is speeded up, the reaction potential in the graphite felt electrode is lower.This paper mainly used sulphuric acid, Prussian Blue, electrochemical oxidation anode to modify graphite felt electrode materials. Comparing characteristics of the resulting cyclic voltammogram(CV) before and after the modification. Through the charging and discharging experiment, energy efficiency, voltage efficiency and current efficiency was compared before and after modification. Graphite felt surface resistance and charging and discharging voltage was also measured through the charging and discharging experiment. Then the potential titration was taken, quantitative analysis the oxygen functional group in graphite felt after modification. So that graphite felt after modification can be activated vanadium battery electrode reaction, the transfer of vanadium ions is speeded up, the reaction potential in the graphite felt electrode is lower was confirmed. Finally, SEM experiment offered the graphite felt surface morphology before and after the modification.