Graphene And Prussian Blue Modified Carbon Felt Electrode And Its Application In All Vanadium Redox Flow Battery

Vanadium redox flow battery?VRFB?is a large-scale energy storage technology with long life,which can be matched with solar energy,wind energy and other renewable energy power generation processes.It can be used as peak regulation of power grid to improve grid stability and safety.The electrode materials commonly used in VRFB are porous carbon felts?CF,Carbon Felt?,and the main problems are as follows:poor conductivity,small specific surface area,and poor catalytic performance.Therefore,the development of low-cost,high-performance electrode materials plays a major role in promoting the commercialization of VRFB.On the basis of commercial carbon felt,this study used surface modification method to prepare graphene modified carbon felt?G/CF?and Prussian blue composite carbon felt?PB/CF,Prussian blue modified carbon felt?,explored the performance of single cell based on composite carbon felt electrode,through the comparison of the advantages and disadvantages of the two modification methods,laid a theoretical and experimental basis for the development of low-cost,high-performance electrode materials for flow batteries.The results show that the surface area and electrical conductivity of the pristine carbon felt can be improved by surface modification of graphene,and the catalytic performance is improved.At a current density of 80 mA cm^-2,the energy efficiency of the G/CF-based battery after 500 cycles remains above 80%,while the energy efficiency of the battery based on the pristine CF electrode drops to 80%after 100 cycles.In the range of 50-360 mA cm^-2,the G/CF electrode exhibited better cell rate performance than the CF electrode and increased the power density by 13.19%.However,this method has major problems such as uncontrollable surface morphology and high cost.The Prussian blue modified carbon felt electrode was further prepared by the method of electrochemical deposition.The results show that the composite electrode also increases the specific surface area of the pristine carbon felt and greatly improves its catalytic performance.When the deposition potential and the deposition time are 0.1 V?vs.Hg/Hg₂SO₄?and 300 s respectively,PB/CF exhibits the best catalytic performance for the positive electrode reaction,and its surface morphology is controllable,which is more even than the G/CF.At a current density of 120 mA cm^-2,after 1000 cycles,the battery with the PB/CF electrode has higher battery stability than the CF electrode,the energy efficiency is increased by 4.83%,and the battery power density is increased by19.13%.At the current density of 360 mA cm^-2,the energy efficiency and voltage efficiency were increased by 4.57%and 6.09%,respectively,which was consistent with the constant current intermittent titration technique?GITT?.The reaction of Prussian blue and Berlin green to catalyze the positive reactions of vanadium battery by"redox targeting reaction"was proved by means of FTIR?Fourier transform infrared spectrometer,FTIR?.In-situ prepared PB/CF electrode exhibits obvious advantages over the physically prepared G/CF electrode in terms of adhesion,cell performance and raw material cost.In-situ preparation of PB/CF provides a reference for the modification of VRFB electrode with low cost and high performance.Its excellent performance is expected to promote the commercialization of VRBs.