A Study Of Fuel Cell With Redox Couples As The Reaction Medium Of The Cathode

After decades of development,the proton exchange membrane fuel cell has become more sophisticated,however,how to reduce costs,improve performance and reliability is still the main problem currently facing.This paper researches a new type of redox fuel cell,which uses redox couple as a reaction medium to replace the traditional fuel cell oxygen reduction reaction,effectively combines the advantages of fuel cells and flow batteries.The new redox fuel cell reduces the cost and shows good performance at the same time.First,four kinds of redox couple on PAN graphite felt and graphite board as the working electrode cyclic voltammetry electrochemical tests are carried out,the experimental results show that,Fe3+/Fe2+ redox couple has a good electrochemical performance is the best choice as the cathode reaction medium;at the same time,when 2 mm thick PAN graphite felt used as the working electrode effectively improves the response speed and so better to show redox reversibility.Therefore,PAN-based graphite felt is choosen as the cathode electrode material;a small amount of Pt catalyst used in this test has effectively increased the electrode reaction rate.Custom quartz reactor is used to simulation cell cathode environment,regeneration conditions of Fe3+/Fe2+ redox couple are studied to explore the different conditions using the control variable method to explore the influence of different conditions on electricity for regeneration,then the three factors three levels orthogonal test has been carried on,the electrolyte temperature at 70 C,Fe2+ initial concentration of 0.6 mol/L,Pt catalyst loading 1.0 mg/cm3,when Fe2+ conversion rate has reached 51.3%,the result lays a theoretical basis of assembling a single redox fuel cell.Through assembling a single redox fuel cell,and with Japan Kikusui electronic load composed of a single cell test systems,to practice study on a theoretical basis,the use of the control variable method combined with three factors and five levels of 25 times orthogonal experiments results show that when Fe2+ initial concentration of 1.0 mol/L,system temperature at 65 ?,Pt catalyst loading 2.0 mg/cm3,show the best performance of the single cell,the output voltage of 0.66 V,and the output power density up to 180.2 mW/cm2.PAN-based graphite felt is used as a Pt catalyst support herein.Chloroplatinic acid is selected as a precursor,then Pt is got by pyrolysis and it has been verified in the XRD patterns as the single component.Using a field emission scanning electron microscope to characterize PAN-based graphite felt,showing its surface and pores uniformly distributed Pt catalyst particles,effectively improve the mass transfer rate between the catalyst and the redox couple:Fourier transform infrared spectroscopy is used to characterize the graphite felt FT-IR characterization.In the the process of using chloroplatinic acid as a precursor thermal decomposition to support Pt catalyst,it has significantly increased the-OH functional group contents of graphite felt fiber surface,and hydrophilic of the graphite felt has also been improved to provid more active sites,so that the redox catalytic reaction between the Pt catalyst and Fe3+/Fe2+ redox couple is seemed to be more likely to happen at the same time.