Preparation And Properties Of Poly (Aryl Ether Piperidine) Based Anion Exchange Membrane

With the rapid development of society,people are faced with two imminent crises of energy crisis and environmental pollution.Anion exchange membrane fuel cells have attracted widespread attention due to the advantages of high energy conversion rate and environmental friendliness.Compared with mature proton membrane fuel cells,hey have the characteristics of fast oxygen reduction kinetics and low cost.However,the lack of cheap,high conductivity,and good alkali resistance anion exchange membranes limit the development and application of fuel cells.In this paper,different anion exchange membranes containing ether bonds are designed,which the use of diphenyl ether monomer greatly reduced the use of expensive catalysts and the good alkali stability of AEM is demonstrated.The performance of AEMs can be optimized by introducing different third monomers to precisely control the degree of functionalization of the polymers.The polymer backbone was synthesized under by superacid catalysis in using diphenyl ether and N-methyl-4-piperidone as monomers.The effects of temperature and catalyst dosage on the reaction activity were studied.QPEPpi-x membranes were prepared by functionalization with methyl iodide,and the effect of functionalization degree on membrane performance was explored.Among them,the QPEPpi-62 membrane shown the best performance,with an electrical conductivity of 66 m S cm^-1 at 80℃.After soaking it in 1 M KOH solution for 600 h,the electrical conductivity retention was 88%,showing good alkali stability.Since the degree of functionalization of the di-monomer polymer could not be precisely controlled,a third monomer-methyl pyruvate was introduced here to regulate the degree of functionalization of the polymer.Methyl pyruvate was a suitable choice due to its low price and high activity.A series of anion exchange membranes were prepared and tested for performance.The conductivity retention of QPEPMpi-60 membrane in 1 mol L^-1 KOH solution at 80℃for1000 hours was more than 88%,which proved its good alkali stability.The single-cell performance of the QPEPMpi-60 membrane was tested with a fuel cell open-circuit voltage of1.04 V.The maximum output is reached at a current density of 780 m A cm^-2,and the power density was 344 m W cm^-2.Methyl pyruvate could not effectively inhibit the water swelling of the polymers,which limits the performance of AEM.Therefore,2,2,2-trifluoroacetophenone was selected as the third monomer to prepare polymer membranes with different degrees of functionalization.2,2,2-Trifluoroacetophenone could inhibit the water-swelling of the membranes,optimized the microphase separation structure,and improved the performance of the membranes.The conductivity of QPEPFpi-70 membrane was 88 m S cm^-1 at 80℃,and the conductivity retention of the membrane was over 92%after 1000 hours in 1 M KOH solution at 80℃,which proved the excellent alkali stability of the membrane.The fuel cell performance was tested and the QPEPFpi-70 membrane fuel cell reached a maximum power density of 506 m W cm^-2 at a current density of 1160 m A cm^-2.The cell stability was tested,and the battery operated at 200m A cm^-2 for 11 h.