Synthesis And Properties Of Cross-linked Basic Anion Exchange Membrane Fuel Cells

Anion Exchange Membrane（AEM）is one of the core components of Anion Exchange Membrane Fuel Cell（AEMFC）.Its structure and performance have a direct impact on the performance and life of fuel cells,and it is very important to reduce the cost and internal resistance of the battery.In recent years,signification progress has been made in the field of anion exchange membrane,but there are still some problems such as low conductivity and low alkaline resistance.Therefore,the development of anion membrane with high conductivity,high alkaline stability and high dimensional stability is the main point of research on anion exchange membrane.In this paper,three series of cross-linked anion exchange membranes were designed and prepared,and the effects of cationic groups,polymer structure,types of cross-linking and degree of cross-linking on the performance of AEMs were discussed.（1）UV-crosslinkable side-chain type imidazole functionalized poly（arylene ether sulfone）anion exchange membrane.The photosensitive side-chain type chloromethylated poly（arylene ether sulfone）（PSF-HCx-CM200-x）was synthesized by reacting 200%chloromethylated PSF with chalconone,p-hydroxybenzyl alcohol and dichlorosulfoxide.The result polymer was characterized by ¹H-NMR,FT-IR and UV-Vis.PSF-HCx-CM200-x has good photosensitivity and solubility,and the maximum absorption peak at 340 nm.Under UV irradiation,>C=C<of the chalcone structure occurs[2+2]photochemical reaction to form the crosslinking structure,and the maximum crosslinking degree can reach 73.1%.Three kinds of UV-crosslinked side-chain type imidazole functionalized poly（arylene ether sulfone）anion exchange membranes（QPSF-HCx-R200-x）were prepared by quaternization and alkalization of three imidazoles from PSF-HCx-CM200-x.UV crosslinked anion exchange membranes（c QPSF-HCx-R200-x-ymin）with different degree of crosslinking were prepared by UV irradiation for a certain time at room temperature in the swelling state.The IEC values of QPSF-HCx-R200-x films before and after cross-linking were in the range of 1.25 to 1.57 mmol g^-1.Compared with uncrosslinked films,the initial decomposition temperature and tensile strength of UV crosslinked films are increased by 7℃and 9.8 MPa.On the contrary,the water absorption and swelling ratio of crosslinked membrane decreased by 39.43%and 30.19%at 80℃.The ionic conductivity of AEM films increases with the increase of cation content and temperature,and the maximum value ofσis 139.87 m S/cm at 80℃.After cross-linking,σdecreases a little.After soaking in 1 mol/L Na OH solution at 60℃for 20 days,the initial values of IEC andσof the uncrosslinked membrane remain70.51-85.67%and 65.31-87.29%,respectively.While those of the crosslinked membrane remain 77.87-90.82%and 72.13-90.14%,respectively.The results show that UV photocrosslinking significantly improves the dimensional stability,thermal stability,mechanical properties and alkaline stability of anion exchange membrane.（2）Thermally crosslinkable side-chain type piperidine functionalized poly（arylene ether sulfone）anion exchange membrane.Firstly,side-chain chloromethylated poly（arylene ether sulfone）（PSF-CMx）with chloromethylated rates of 130%and 150%were synthesized by the above method.Then,piperidine functionalized poly（arylene ether sulfone）anion exchange membrane（QPSF-Pipx）was prepared by piperidine quaternization and alkalization.By changing the ratio of2,4,6-tris（dimethylaminomethyl）phenol to piperidine,thermal crosslinked membrane（c QPSF-Pipx-y-TAPy）with different degree of crosslinking was prepared through heating,and the highest degree of crosslinking was 55.13%.The IEC value of QPSF-Pipx membrane before and after cross-linking was between 1.38 to 1.67 mmol g^-1.Compared with the uncrosslinked membrane,the initial decomposition temperature and tensile strength of the thermally crosslinked membrane are increased by 9℃and 15.1MPa,respectively.At 80℃,the water absorption and swelling ratio of the thermally crosslinked membrane are decreased by 75.4%and 78.4%,respectively.The maximumσappeared at 80℃with the value of 138.7 m S/cm,and theσof the membrane is slightly reduced after cross-linking.After soaking in 1 mol/L Na OH solution at 60℃for 20 days,the initial values of IEC andσof QPSF-Pipx remain70.51～74.34%and 65.31～72.49%,respectively,and the initial values of IEC andσof crosslinked membrane remain 78.87～90.94%and 72.19～93.02%,respectively.Thermal crosslinking also significantly improves the dimensional stability and alkaline stability of the membrane.（3）UV crosslinkable ion cluster type fluorinated poly（arylene ether）anion exchange membrane.The photosensitive poly（arylene ether）（PSFPAE）was synthesized by polycondensation reaction using bisphenol A,dihydroxylchalcone and perfluorinated biphenyl,and then the tertiary amine group was introduced to produce the tertiary amine functionalized poly（arylene ether）（PSFPAE-TAP0.5）.The result polymer was characterized by ¹H-NMR,FT-IR and UV-Vis.PSFPAE-TAP0.5 has good photosensitivity,and has the maximum absorption peak at 324 nm.Under UV irradiation,the polymer forms a cross-linking structure,with the maximum cross-linking degree of 59.1%.The UV-crosslinked ion cluster type fluorinated poly（arylene ether）anion exchange membrane（QPSFPAE-QA0.5）was prepared by quaternization and alkalization of PSFPAE-TAP0.5,and the crosslinked AEM membrane（c QPSFPAE-QA0.5-6min）was prepared by UV irradiation in swelling state at room temperature.Before cross-linking,it is soluble in DMAc,NMP and other solvents,but insoluble in any solvent after crosslinking.Compared with the uncrosslinked membrane,the initial decomposition temperature and tensile strength of the crosslinked membrane were increased by 5℃and 8.1MPa,respectively.QPSFPAE-QA0.5 show a high IEC value of 2.01 mmol g^-1,and a low water absorption and swelling ratio of 45.7%and 7.0%at 80℃,respectively.After UV cross-linking,the water absorption and swelling rate of QPSFPAE-QA0.5 decreases by 13.4%and 28.5%,and the swelling rate is as low as 5.0%.At 80℃,theσvalue of QPSFPAE-QA0.5 was 158.8 m S/cm.After cross-linking,theσvalue of QPSFPAE-QA0.5 was maintained a high level of 139.7m S/cm.After soaking in 1mol/L Na OH solution at 60℃for 7days,the IEC andσvalue of the UV crosslinked membrane still remain 91.7%and 91.6%of the initial value.UV-crosslinked AEM containing fluorine and ion clusters can not only improve the ionic conductivity,but also improve the alkaline stability and dimensional stability,which provides potential materials for the application of anion exchange membrane fuel cells.