Investigation Of Vanadium Redox Flow Battery And The Mechanism Of Its Electrode Reaction

All vanadium redox flow battery is a new-style and environmentally friendly energy storage battery that has many characteristics such as instant recharge by replacing the spent electrolytes,discharged at large current density,really fully discharged(100%), increasing storage capacity easily,a theoretically unlimited life, sim-ple operation and maintenance.Therefore,it is undergoing a exciting development and commercialization.However,there are still some questions to be solved during its commercialization,such as how to prepare highpurity vanadium electrolyte ,to enhance its energy density and efficiency,to improve its charge/discharge performance.So it is very important for improving the perfoemance of vanadium redox flow battery and its commercialization to select adaptive electrode materials,to investigate the mechanism of the electrode reaction and to select some additives.In this paper,high concentration vanadium electrolyte has been prepared by electrolysis,graphite and graphite felt electrode also have been made,moreover,the electeodes have been activated,and based it ,a lab-level vanadium battery has been manufactured. Cyclic voltammetry ,current step and invariable current charge/discharge method have been used to study the reactive mechanism of electrolysis, of vanadium electrode reaction and of electrode activation,also to investigate maiden charge process and electricity performance of vanadium battery.The influence of electrode activation and trace stibium ion, indium ion added into vanadium electrolyte has been discussed. Electrolysis by which high vanaiudm electrolyte, such as 5mol/L VOSO4 + 5 mol/LH2SO4,can be prepared may benifit commercialization of vanadium battery.Conditions of electrode can affect greatly the vanadium electrode reaction,even reversibility of it.The graphite electrodes treated by acid and heating can enhance the reversibility and kinetic of the electrode reaction. The redox of V(â…£)/V(â…¤) , V(â…¡)/V(â…¢) couple on the graphite displayed one electron quasi-reversibility.It is proved that trace In3+,Sb3+ can inhibit cathodic hydrogen evolution during the charge process by increasing the hydro-gen overvoltage in addition that Sb3+ is a stabilizing/kinetic enhancing ion.During the charge/discharge process,cross-mix and self-discharge rarely happened.The maximal energy density of the lab-level vanadium battery is 21 Wh/kg.The capacity efficiency of the lab-level vanadium battery is as high as 94.7%...