Study On Modification Of Graphite Rod Electrode With Energy Storage Vanadium Liquid

All vanadium redox flow battery(AVRFB) developed quickly in recent years is a green andlarge electrochemical energy-storage battery.It possesses many advantages compared with otherconventional storage batteries such as long life,low price,fast charging,fully discharged,environmental friendly,high storage efficiency and low operating and maintenance costs.Forthese reasons,it draws mang researchers’attention and gets rapid development in China andforeign countries.Vanadium flow batteries has been widely used in solar power,wind power,peaking power plants,electric vehicles power supply,emergency power systems and soon.However,the development of vanadium redox flow battery is affected by three mainfactors:the electrode materials,electrolytes and membrane.Nowadays,carbon fiber electrodes,metal electrodes and conductive plastic composite electrodes are used in VRB.Graphite felt(GF)is a typical electrode of VRB which has good stability, high surface area and lowcost.However,graphite felt surface is hydrophobic,the electrochemical activity is poor andelectrode reaction reversible is not good.It is necessary to modify to enhance electrochemicalactivity and reversibility.The main purpose of this research is to study modification and electrochemical performanceof the electrode materials.CV,AC impedance spectrum and charge-discharge techniques wereused to test the electrode and evaluate electrochemical properties of V(Ⅳ)/V(Ⅴ) on electrodesbefore and after modification.The main conclusions can be summarized as following:By CV Prussian blue was electrodeposited in the graphite rod electrode surface for surfacemodification.Te modified electrode electrochemical activity was significantly enhanced,theoptimal deposition conditions is deposition solution pH:2.0;deposition rate:50mV/s;depositionquantity:50deposition cycles.In0.5-1.2V,there are two characteristic peaks,the peak potentialvalue corresponding in V(Ⅳ)/V(Ⅴ) for the oxidation and reduction of the electric peaks.Withthe increase of the scanning-rate,the peak current and distance between the peak potentialadd.Multiple cycle test,100times of scanning later,the current conservation rate of the graphiterod was still as high as85%.The V(Ⅳ)/V(Ⅴ) couple was aquasi-reversible process controlledby the diffusion of the mass transfer process.After potassium permanganate electrochemical oxidation treatment,electrochemical activityof GF electrode is significantly increased.The optimal treatment condition:current density of75mA/cm2,the oxidation time of600s.Results of FT-IR showed that after the modificationelectrode surface oxygen functional groups increased,the surface roughness increased,the peakpotential difference decreased,the peak current increased.The AC results showed that the electrode process of V(Ⅳ)/V(Ⅴ) on graphite wascontrolled by electrochemical reaction anddiffusion.