Preparations And Properties Of Polyacrylonitrile Based Exchange Membranes For Fuel Cells

Faced with the severe situation of energy crisis and environmental deterioration,it has become an inevitable trend to develop a"green"and"safe"new energy source.Fuel cell,as one of the most potential energy utilization methods,because of its advantages of high efficiency,cleanliness,safety,reliability,has been widely studied by scholars at home and abroad.Polymer electrolyte membranes,which are the key components of fuel cells,have become a hot research topic.Recently,the main research focus is proton exchange membrane and anion exchange membrane.For the long-term market-occupied Nafion membrane,there are some disadvantages such as high price and complex preparation process.Based on the above research status,the research contents of this paper are as follows:（1）Acrylonitrile-styrene-acrylamide2-methylpropanesulfonicacid（AN-St-AMPS）proton exchange membrane was prepared by free radical solution polymerization.On the one hand,AMPS was involved in the polymerization,and a large number of sulfonic acid groups were introduced to improve the proton conductivity and hydrophilicity of the membrane.On the other hand,the addition of oil-soluble monomer styrene improved the problem of decreasing the dimensional stability,which caused by too many sulfonic groups.The results show,the water absorption of AN-St-AMPS 50 membrane is 42%,and the proton conductivity can reach 1.4×10^-3S/cm at 80^oC.The swelling degree of AN-St-AMPS 50 membranes is only 8.6%at room temperature.When the content of AMPS increased from 20%to50%,the tensile strength of proton exchange membranes decreased from 31.79 MPa to 16.65 MPa..In addition,the proton exchange membrane has excellent thermal stability and oxidation stability.（2）Imidazole-type anion exchange membrane was prepared by in situ polymerization of polyacrylic and iodized 1-vinyl-3-methylimidazole（[VMIm][I]）ionic liquid.FTIR analysis confirmed that the ionic liquid was successfully polymerized into polyacrylic matrix.SEM electron microscope showed that the ionic liquid had good compatibility with polyacrylic matrix.In addition,the alkali resistance and thermal stability of the membrane were improved by the introduction of imidazolium cations.The results showed,when the anion exchange membrane was immersed in 2M NaOH solution for 240 h,the structure of the membrane did not change,and the ion conductivity remained about 92%of the original.When the mass ratio of the polyacrylonitrile to the ionic liquid is 1:1 under the condition of 80^oC,the hydroxyl conductivity of the membrane reaches 1.35×10^-33 S/cm,and meanwhile,the introduction of the ionic liquid reduces the tensile strength and the elastic modulus of the membrane,the flexibility of the membrane is increased.