| Aqueous organic flow battery is a new type of flow battery.The battery system has the characteristics of low cost,rich sources of active materials,and battery performance that can be designed and tailored.The electrode material is the reaction site of the redox couple,so it occupies an important position in aqueous organic flow battery system.However,the commercial electrode-carbon felt electrode has shortcomings such as small specific area and poor electrochemical catalytic activity,so it is necessary to modify it to achieve the purpose of improving battery performance.In this paper,firstly,the adsorption behavior of the five isomers of dihydroxyanthraquinone on different carbon materials was calculated,and the adsorption behavior and electronic transition ability were studied from the perspective of molecular dynamics.Secondly,graphene self-assembly,alkaline etching and nickel chloride etching are used to modify the carbon felt electrode.SEM,XRD,XPS,Raman and other physical testing methods are used to characterize the surface morphology,crystal structure,element content,and surface state of the modified electrode.Electrochemical methods such as cyclic voltammetry,AC impedance,and single cell are used to study the influence of factors such as pretreatment method,metal salt etching time,and type on the electrochemical performance of the modified electrode.The results of the study show that through simulation calculation,the optimization shows that the adsorption energy of benzene ring and carbon material in1,8-DHAQ is in the middle and its electronic transition ability is optimal compared with the other four isomers.The carbon felt after alkali etching can increase the loading capacity of three-dimensional graphene,the electrochemical performance has been improved,and the coulombic efficiency has increased by about 10%.The carbon felt material is heat treated for different time,and it is concluded that the effect of treatment at 500℃ for 4 h is the best.Different metal salt types and heat treatment time have different etching performances of carbon felt materials.Among them,the etching effect of 1 mol/L nickel chloride at 400℃ for 6 h is the best.The surface of Rayon-based carbon felt etched by nickel chloride has dense pores,while the surface of PAN-based carbon felt has larger pores.Compared with PAN-based carbon felt,Rayon-based carbon felt has a larger specific surface area.This shows that the etching reaction of nickel chloride on different materials has different catalytic effects and the catalytic activity of the carbon felt after etching is increased by nearly 4 times.The charging and discharging test results of the single cell show that,compared with the pure carbon felt electrode,the charge and discharge capacity and coulomb efficiency of the etched porous electrode have been improved to varying degrees. |
