Investigation Of Electrodes For High-power Vanadium Redox Battery

Energy shortage and environmental pollution caused by fossil fuel force people to promote the development and utilization of renewable energy.Renewable energy,such as solar,wind and hydro energy,has many advantages with clean and inexhaustible,however,the intermittent of renewable energy can limit its large-scale utilization.The development of large-scale energy storage system makes up this defect.All-vanadium redox flow battery is considered as one of the most promising flow battery for energy storage system due to their low cost,environmental friendly and so on.The key materials of vanadium redox flow battery such as electrode and ion exchange membrane are introduced in this paper.Moreover,the mechanism operation of vanadium battery is studied.The electrochemical activity of electrode and their cell properties were investigated by cyclic voltammetry and charging-discharging test,including:1?The catalyst of vanadium ions redox reaction was fabricated by electrochemical polymerization with p-aminobenzenesulfonic acid on the surface of graphite fiber.There are abundant oxygen-containing groups and nitrogen-containing groups on the surface of catalyst.The catalyst showed excellent electrochemical catalysis toward to VO²⁺/VO₂⁺and notably restrained hydrogen evolution.The charging voltage of electrode was decreased by 80 m V,and the discharging voltage is increased by 70 mV at the current density of 100 m A/cm².The treated electrode exhibited higher energy efficiency and voltage efficiency at the large current density compared with the untreated electrode.2?The monopotassium phosphate is used as raw material toprepare P,O co-doped graphite felt electrode,which was distributed on the electrode by recrystallizing.The P-containing groups and O-containing groups were generated by annealing on the surface of electrode,which mainly included C-P bond and O-P bond.The treated electrode presented four prominent reduction peak and hindered the hydrogen evolution in the negative direction,compared with original electrode.The untreated electrode stoped charging and discharging at the current density of 120mA/cm²,the energy efficiency of the P,O co-doped electrode is 78%.The treated electrode presents high stability and electrochemical catalysis property for 1000charging-discharging operation at the current density of 150 m A/cm².