Preparation And Properties Of Poly(Arylene Ether Ketone)s Ion Exchange Membranes Materials For Fuel Cells

As a new type of energy conversion device,fuel cells have the advantages of low environmental pollution,high reliability,and high specific energy.Polymer electrolyte membrane fuel cell with polymer membrane as electrolyte material is one of the most promising fuel cells.As one of the most important components of polymer electrolyte membrane,the comprehensive performance of polymer electrolyte membrane would affect the performance and life of fuel cells.The polymer electrolyte membrane acts as a barrier between fuel and electrons and needs to conduct ions.According to the conduction ion type,it can be divided into proton exchange membranes and anion exchange membranes.At present,the preparation process of commercial ion exchange membrane materials is complicated and expensive,and the ion conductivity drops sharply under the condition of large amount of water loss.Therefore,the development of new polymer electrolyte membranes with low cost and high performance has become an important link to promote the sustainable development of fuel cell technology.At present,the problems facing the development of polymer electrolyte membranes mainly focus on the following two aspects:for proton exchange membranes,the development of proton exchange membranes that can replace expensive Nafion membranes with low cost,simple preparation technology,good physical and chemical properties,and high proton conductivity;anion exchange membranes materials with good alkali resistance and high ionic conductivity have been developed.In this paper,in order to solve the problem that the proton conductivity and mechanical properties of sulfonated aromatic proton exchange membranes decrease sharply under the condition of medium and high temperature,the methods of side chain sulfonation and organic-inorganic modification are adopted.Sulfonated poly（arylene ether ketone sulfone）s with amino groups（Am-SPAEKS-DBS）was synthesized by polycondensation reaction and grafted onto 2-acrylamide-2-methylpropyl sulfonic acid（AMPS）to obtain polymer matrix with sulfonic acid groups in both main chain and side chain.ZIF-67 with open metal site Co²⁺were prepared by solvothermal method.Then ZIF-67 was introduced into the polymer as inorganic filler to prepare a series of Am SDA-Z7-x hybrid membranes.The prepared composite membranes showed good thermal stability and mechanical properties.Meanwhile,Am SDA-Z7-10%hybrid membranes showed the highest proton conductivity at 80 ^oC,up to 0.116 S cm^-1,which was 1.53 times higher than that of pure membranes and higher than Nafion 117(0.100 S cm^-1).Although organic-inorganic blends can improve the proton conductivity and dimensional stability of the polymer electrolyte membrane,the loss of MOFs in the polymer would lead to a decrease in the proton conductivity of the membranes.In order to make the MOFs filler exist stably in the polymer,we bonded the MOFs filler with the polymer main chain through chemical bonds.Sulfonated poly（arylene ether ketone sulfone）s with amino was obtained by acylation of sulfonated poly（arylene ether ketone sulfone）s with amino as main chain（Am-SPAEKS-Cl）.Then,Ui O-66-NH₂with proton conduction ability was prepared by hydrothermal synthesis,and Ui O-66-NH₂was bonded with polymeric main chain by Hinsberg reaction,and a series of organic-inorganic hybrid membranes were prepared.Am-S-U-6%membrane exhibited the highest proton conductivity of 0.168 S cm^-1at 80 ^oC,which was two times higher than that of pure membrane and much higher than Nafion 117(0.100 S cm^-1).This was mainly because the sulfonimide has the same proton dissociation ability as sulfonic acid groups at high temperature,which ensured the continuity of proton conduction of the hybrid membranes.After soaking in deionized water for 10 days,the weight loss of Am-S-U-6%membrane was only 1.2%.The results showed that the chemical stability of Am-S-U-6%composite membrane was effectively improved by the way of chemical bonding,which fixed Ui O-66-NH₂on the polymer backbone chain.For anion exchange membranes,the introduction of inorganic fillers can also improve its ion conductivity and mechanical stability.We selected poly（ether ether ketone）with good mechanical properties as polymer matrix and functionalized its imidazole.Then ZIF-8 and GO/ZIF-8 with good alkali resistance and ion conductivity were prepared by solvent-thermal method and introduced into polymer as fillers to prepare a series of organic-inorganic anion exchange membranes.The series of hybrid membranes showed good alkali resistance stability and high ionic conductivity.After soaking in Na OH（2 M）solution at 60 ^oC for 400 h,the ionic conductivity of Im PGZ8-1%was still 92.01%of the initial conductivity,and the ionic conductivity of Im PGZ8-1%at 80 ^oC and 100%RH reached 0.087 S cm^-1.This was mainly because ZIF-8 contained a lot of imidazole,which could provide sites for ion transport.At the same time,ZIF-8 grew in situ on GO,and the amino groups on the main chain formed hydrogen bonds with the hydroxyl group in GO,which was more conducive to ion conduction.Most metal-organic frameworks are easy to collapse under alkaline conditions.The performance of composite films would be affected.From the perspective of molecular design,poly（arylene ether ketone）with amino groups（Am-PAEK）was prepared by polycondensation reaction,and different length of alkyl side chains were grafting,and then imidazole cationic groups were grafting to the end of side chains by bromination reaction to construct obvious hydrophilic/hydrophobic phase separation structure.And a series of anion exchange membranes containing different length of alkyl side chains were prepared.The Im-AP anion exchange membranes showed good alkali resistance stability and high ionic conductivity.When Im-AP-x membranes were immersed in Na OH（1 M）solution at60 ^oC for 168 h,the alkali-resistant stability of the membranes was still up to 84%.After30 days of long-term stability testing,the residual weight and ionic conductivity of the Im-AP membranes remained at 95%and 90%of the initial amount.The highest ionic conductivity of Im-AP-6 was 0.127 S cm^-1（80 ^oC,100%RH）.The open circuit voltage（OCV）and peak power density of the Im-AP-6 membrane were 1.13 V and 389.71 m W cm^-2（80 ^oC,100%RH）.The results showed that the series of membranes showed excellent battery performance and had good application potential and prospect in alkaline fuel cells.