Design,Synthesis And Application Of Ferrocene Derivatives In Organic Redox Flow Batteries

With the devebpment of society and the nassive exploitation of fossil fuel,people are eager to find enviromTCntally friendly renewable energy.The redox flow battery(RFB)is an important technology for large-scale electrical energy storage owing to the unique structural characteristics.Faced with serious challenges,the traditional RFB is toxic and expensive.However,the organic redox flow battery(ORFBS)have obtained a wide range of application due to its abundant resources and easy tunability.Nonetheless,the disadvantages of low solubility,poor stability and low energy density limit its wide applications.In this paper,to overcome the problems of low energy density and electrolyte contanination in the battery,and owing to the characteristics of cheap,stable,high rate constant and diffision coefficient of ferrocene,the modified ferrocene derivatives were selected as the research object.After learning the research progress of ORFBS,a variety of benzi]idazDoium salts were synthesized.The solubility of FCEZ+-TFSI in EC/DMC reached 1M,which was better than the solubility of the ferrocene derivative that had been published.The redox potential also increased to 0.54 V and 0.84 V(vs.Ag/AgCl).Under the charge and discharge current density of 0.48 lA cnT2,the Coulomb efficiency was maintained above 99.9%and the energy efficiency was above 80%in 135 cycles.The research of FCEZ+-TFSI shows high energy density,which benefits the developnent of ORFBS.In the following work,in order to solve the problem of electrolyte contanination and inprove the solubility,a highly water-soluble artificial bipolar molecule containing cathode-active ferrocene moiety and anode-active bipyridinium moiety were realized and used as the sole active material in the symmetric ORFBS.The solubility of the synthesized Fc-bipy3+ trichloride salt reached 1.2 M in water,and the potentials of the two redox couples were-0.54 V and 0.15 V(vs.Ag/AgCl).At a current density of 10 mA cm-2,the battery boosted the cyclability to 4000 cycles with capacity retention of ca.75%at 100%depth of discharge.In the reverse polarity test,the cell showed high symmetry and stability,which provided a viable solution for electrolyte contalination in RFBS.In the above work,a series of ferrocene derivatives molecules were synthesized by cheap and renewable materials,which contributed to solving the challenges and problems in the practical applications of RFBS.