Preliminary Study Of Carbon Fiber Paper For Proton-exchange Membrane Fuel Cells

Fuel cell power was considered as the first choice power generation technology in 21st century because of its high energy conversion efficiency and lower pollution. Carbon fiber paper, one of the key raw meterials used in gas diffusion layer, had not achieved industrialization in china. Because of immature prepare techniques, domestic research samples were not as good as import commercial samples. This situation quite restricted the development of fuel cell in China.In this paper, in order to resolve the defect of lacking tenacity,low electrical conductivity and uniform pore size distribution of carbon paper,the characterization of tenacity and the effects of carbon fiber,resin and carbonization temperature etc were discussed and analyzed in detail; Besides, the effects of carbon fiber(length,diameter,surface characteristics,species),resin and the transformation of carbonization temperature to the carbon paper physical properties were analyzed, and the structure of pore and surface shape of paper were also discussed.The result showed that using the method of fixing load power to test bend degree could reflect diversity of different paper tenacity and in laboratory condition the method is feasibility. The carbon fiber diameter,carbon fiber surface characteristics,varieties of resin and carbonization temperature affected the tenacity,structure and properties of carbon fiber paper directly. The treatment of coupling agent not only could enhance the dispersion of carbon fiber and improve the formation of carbon paper, but also improve the interface felt state between fiber and resin.For the composite of fiber and resin like the carbon fiber paper, the bond strength of interface between fiber and resin influenced its tenacity considerable.when the bond strength is weak or moderate ,the paper will rupture resilient,otherwise it will rupture brittlely in the case of good bond strength.In this paper, the properties of the paper were relatively the best and the pore size distribution were uniformity when the length was 5mm,the diameter was 5.6μm, and carbon fiber possess of more surface oxygen-containing groups. The optimum properties were obtained when the dosage of coupling agent was 2%, on this condition, compared with the untreated carbon fiber paper, the porosity and strength increased; the optimum carbon paper properties were obtained when the material was resinC , the porosity,electrical conductivity and the degree of graphitization of the carbon paper increased, interlayer distance ( d002)decreased as increased the final heat treatment temperature.The optimal properties of carbon fiber paper were as follows: thickness0.22mm, density0.44g·cm-3, porosity72%, electrical resistivity(in plane)5.5m?·cm, electrical resistivity(through plane)80m?·cm, tensile index42.4Nm·g-1, permeability11.4ft3.min-1,which were as good as commercial carbon fiber paper and satisfied the application requirement.