Preparation And Characterization Of Sppesk Electrospun Oriented Fibrous Composite Proton Exchange Membrane

At present, Nafion is a kind of PEM which is used widely in PEMFC, but its high cost, high methanol permeability, hydrogen penetration and other disadvantages limit the PEMFC developping. The non-fluorinated PEMs with aromatic ring become one of the hot spots in scientific researchs, because of the low cost and low methanol permeability, but non-fluorinated materials have a low conductivity. Usually, the proton conductivity of non-fluorine PEMs are improved by increasing the number of ionic conduction group, but excessive amounts of ionic conduction group will make PEM excessive swelling. Electrostrospinning method can make nano-fibers by applying a electric field, PEM prepared by nano-fibers has the proton continuous channels, which improve the proton conductivity of the PEM. Another, the fibers support can improve the swelling resistence of membrane, balancing the proton conductivity and swelling properties. In this paper, fiber composite thick-aligned PEMs were prepared based on the electrostrospinning method, sulfonated poly (aryl ether sulfone ketone) (SPPESK) as base material. To improve the membrane proton conductivity in the thickness direction and excellent material compatibility is not reported at home and abroad.Firstly, the SPPESK nanofibers were prepared by electrospinning for exploring the conditions affecting on preparation of nano-fibers. For example, electrospinning solution, injection velocity, voltage, roller speed. The optimal spinning conditions were determined,20 kv as the electrospinning voltage,1000 rpm as the roller speed,6?L/s as the jet velocity, 20.2wt% as the concentration of electrospinning solution. The range of fibers diameter is 100-300nm.Secondly, to examine the performances of the suface-aligned fiber composite membrane with the different IEC, and using the same IEC(1.82mmol/g) SPPESK blocked the fiber membranes. Study by optimizing experiments showed that under 80? the surface conductivity can be up to 163 mS/cm in parallel to the fiber direction for IEC1.82mmol/g suface-ordered fiber composite membrane, as 1.16 times that of cast, as comparable to Nafion115 membrane(153mS/cm). Swelling degree of the suface-ordered fiber composite membrane was only 22%, as comparable to Nafionl 15(21%), lower than the cast membrane (29.1%)In order to improve the conductivity cross PEM, when IEC1.82mmol/gSPPESK fiber membranes with superposition were infiltrated and dried, then after cutting, flatting, drying, protoning, the SPPESK fiber thickness-aligned composite proton exchange membrane was prepared. Studies have shown that the thickness-ordered membrane with smooth could improve the surface compatibility of membranes and reduce the anisotropy of membranes; thick-aligned membrane had more excellent electric and chemical properties and mechanical properties. Under 80?, proton conductivity cross the membrane was 30.0 mS/cm and swelling degree was only 23.0%; which are comparable to Nafionl 15(36.0mS/cm,21.0%), The tensile strength reached 19.3 MPa far higher than Nafion115.In the single battery operation, hydrogen penetration current density reached 2.37 mA/cm2, open circuit voltage reached 0.95V, which expained the thick-aligned membrane have a good fuel resistence. Power density was 295 mA/cm2, as 1.28 times than that of Nafion115 membrane,.