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Activation treatment of graphite felt used for vanadium redox flow battery

      This way has an advantage of stable oxidation reaction and easy control,the graphite felt after electrochemistry treatment shows that the voltage efficiency can be reach 85%,and the current efficiency can reach 95%,and the circle property is very stable.after the analysis of XPS and FT-IR,the results show that the effect of electrochemistry treatment mainly increase the quality of the O/C rate on the surface of graphite felt,especially to the number of COOH.the results of SEM and (BET)/N2 show that the electrochemistry treatment can increase the surface area of the graphite felt,and increase the reaction area of the electrode.the electrochemistry treatment reduce the electric resistance of the graphite felt,the reason is mainly from the increasing of the COOH number on the surface of the graphite felt.

  The nitrogen treatment is make the graphite felt under the 180℃ situation of heating in water bath.after the experiment,the result shows that the best treatment time is about 15h,and.use the graphite felt after treatment as electrode in the vanadium redox flow battery,it can charge and discharge in the range of 20~60 mA/cm2.when the current density reach the 20 mA/cm2,the voltage efficiency can reach 83.7%,and the electric energy efficiency can reach 85.3%.

  Through the electrochemistry research and test,the result shows the reason why it can improve the activity of the graphite felt:the nitrogen containing functional groups on the surface of the carbon fiber increased,the functional groups improve the acid base property of the functional groups and the charge density of the carbon atom,reduce the electric resistance,so the activity of the graphite felt is been improved,and increase the efficiency of the vanadium redox flow battery.