| Anion exchange membrane fuel cells?AEMFC?are a new type of power generation device,which has the advantages of environmental friendliness and low cost.As the core components of the AEMFC,the anion exchange membrane needs to have both high ionic conductivity and excellent dimensional stability.Traditional casting method is not easy to improve the conductivity while reducing the swelling ratio of the membrane.The addition of inorganic substances such as SiO2,graphene oxide,and carbon nanotubes can improve the ionic conductivity and the swelling resistance of the membrane,but there is a problem that the inorganic/organic compatibility is poor.In this paper,an imidizolium polysulfone doped functional carbon nanotubes fiber-reinforced anion exchange membrane was successfully prepared by electrospinning.The fibrillation of imidazolium polysulfone in a strong electric field and the orientation of the carbon nanotubes along the fiber axis formed a long-range ordered ion-conducting channels.The fiber-reinforced networks has effectively improved the ion conductivity,swelling resistance and mechanical and thermal stability of the composite membrane.Firstly,imidazolium polysulfone?PSF-ImOH?was prepared by chloromethylation and imidazoleization of polysulfone.The characteristic peak in the 1H-NMR?5.38 ppm,9.05 ppm?indicates the successful preparation of imidazolium polysulfone?PSF-ImOH?.In a nitrogen protected environment,amidation and quaternization of carboxylated multi-walled carbon nanotubes were performed to prepare imidazole-functionalized carbon nanotubes?FCNT?.The appearance of the infrared vibration absorption peak(1490 cm-1)of the n-butyl methylene bromide and the thermal decomposition of imidazolium groups in air at 200°C indicate the successful preparation of FCNT.The PSF-ImOH/FCNT casting membrane was prepared by the casting method.The membrane was dense and non-porous,and thickness of the membrane was about 25?m.The properties of the casting membrane under different FCNT doping levels were studied and the optimal FCNT doping amount was 0.4wt%.Next,the effect of solution concentration,applied voltage and roller rotation speed on the morphology and diameter distribution of electrospun fibers was investigated experimentally.The optimum electrospinning conditions were determined as follows:solution concentration is 20wt%,loading voltage is 18 k V and the rotating speed of the roller is 1500 rpm.The electrospinning is performed under the optimal conditions.The FCNT is oriented in the axial direction of the fiber.The obtained fiber is subjected to hot pressing progress to obtain PSF-ImOH/FCNT electrospun membrane.The electrospun membrane is dense and defect-free and retains a certain fiber morphology,and the membrane thickness is 25?m.The performance of the electrospun membrane was better than that of the casting membrane under the same conditions,and the optimal FCNT doping amount was 0.4 wt%.Finally,the influence of injection pump speed and applied voltage on the morphology and diameter distribution of coaxial electrospun fibers was investigated experimentally.the optimum coaxial electrospinning conditions were determined as follows:injection pump speed is 0.06 ml/h and the applied voltage is 28 kV.Coaxial electrospinning is performed under the optimal conditions,FCNTs are confined within the core of the fiber and oriented along the axial direction of the fiber,improving the inorganic/organic compatibility.The obtained fibers were subjected to hot pressing treatment to obtain PSF-Im OH/FCNT coaxial electrospun membrane.The surface of the membrane was dense and defect-free,retaining a certain fiber morphology,and the membrane thickness was 25?m.The swelling ratio,hydroxide conductivity and mechanical tensile strength of the coaxial electrospun membrane with 0.6wt%FCNT were 10.5%?60°C?,49.7 mS cm-1?60°C?and 17.5 MPa repectively,which were as 0.91,1.19,and 1.1 times as FCNT uniformly distributed electrospun membranes. |
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