Synthesis Of Fe And Phenol Based Electrode Materials And Their Application In Redox Flow Battery

After the industrial revolution,energy,as the driving force of human production and life,become the guarantee of human social development.With the increasing demand of energy,the environmental problems caused by energy are becoming increasingly prominent.The huge pollution caused by fossil energy has affected the quality of people's life.People have to look for new energy materials to replace traditional fossil fuels.New energy sources such as wind energy,solar energy,and tidal energy have been developed by humans,but they cannot output stable electricity due to environmental factors.Electrochemical energy storage based on liquid flow battery has attracted great attention due to its flexible and adjustable active substances,large output power and battery capacity,and more solvent selection.Nowadays,the reported electrode materials for redox flow batteries have many problems,such as high cost,degradation difficulty of active materials,low solubility,rapid decay of charge/discharge capacity and so on.To solve these problems,iron-based and phenol electrode materials were synthesized in this paper.They can solve these problems by ion exchange or modifying hydrophilic functional groups.In this project,the synthesis of cathode materials for flow battery was studied,and their properties and performance were investigated.Two derivatives are mainly introduced on the iron-based electrode materials,ferrocene derivatives and ammonium ferricyanide.Ferrocene itself has high redox activity but its water solubility is not good.In order to meet the requirements of aqueous flow battery,ammonium sulfonate was modified to increase the solubility in water,so it becomes suitable for aqueous flow battery.Potassium ferricyanide is often used to prepare cathode electrolyte because of its excellent redox activity.Ammonium ferricyanide was obtained by ion exchange of potassium ferricyanide.In addition to inheriting the advantages of potassium ferricyanide,its ammonium ion has better conductivity than potassium ion and is more suitable for electrode materials.Hydroquinone as the active center has good redox activity.On this basis,three hydroquinone salts were synthesized and their redox properties were studied in this project.Levodopa has always been used as a medical drug,and its electrochemical properties have not been studied yet.Its redox activity was tested,and assembled it with zinc anode to test its charge/discharge performance.This project has completed the following research work:(1)Based on the excellent redox activity of ferrocene as the active center,a ferrocene derivative,Fc-SO₃NH₄,based on ferrocene was synthesized.In terms of molecular design,the introduction of ammonium sulfonate group improved the water solubility.In addition,in the synthetic route from the sulfonation of ferrocene to the acid-base neutralization reaction,except for the solid ferrocene itself,the reactants in each step are in the form of liquid,which simplifies the post-treatment process of the reaction and is conducive to commercial production.In the Fc-SO₃NH₄ solubility test,a UV-vis spectrophotometer was used to carry out the solubility test,and the solubility in different solutions was compared.In the Fc-SO₃NH₄ cyclic voltammetry test,in addition to selecting the conventional sodium chloride solution as the supporting electrolyte,ammonium chloride solution was used as the supporting electrolyte,and the redox reversibility and diffusion coefficient in the two electrolytes were compared.In the charge/discharge test of the battery assembled with Fc-SO₃NH₄ as the catholyte and zinc anode,different supporting electrolytes were selected.The coulombic efficiency,energy efficiency and voltage efficiency of different electrolyte batteries were compared.The reasons for the decay of the charge/discharge capacity in different supporting electrolytes were analyzed,and the charge/discharge capacity decay was improved.(2)The cation exchange resin was used to convert potassium ferricyanide into ammonium ferricyanide,the redox reversibility and diffusion coefficient of ammonium ferricyanide were investigated,and the zinc anode was paired to assemble a new flow battery.The concentration of ammonium ferricyanide and the current density of the battery were changed to investigate the impact on the coulombic efficiency,energy efficiency,voltage efficiency,and charge/discharge capacity.Furthermore,the polarization test and current ratio test were carried out to analyze the power density and stability of the battery.(3)Based on the good redox activity of the hydroquinone active center,three salts of hydroquinone derivatives were synthesized,and the redox reversibility and diffusion coefficient of these three salts were study.The redox reversibility and diffusion coefficient of levodopa that is commonly used in medicine were investigated,and they were paired with the zinc anode to assemble a novel flow battery.After the test conditions of the battery and the concentration of levodopa were changed,these were analyzed,including the coulomb efficiency,energy efficiency and voltage efficiency of the battery,and the reasons for the decay of charge/discharge capacity.