锌-氧电池中氧催化电极透气的性能

采用不同添加量的造孔剂,制备锌-氧电池中氧催化电极.用自制透气试验装置及BET方法,分析了试验电极透气量数据和带疏水透气膜的催化电极的透气性能.发现疏水透气膜的透气量与造孔剂量符合指数函数关系,为制作微孔结构的疏水膜和微孔电极提供新的构思启示.锌-氧电池耗氧量的计算结果显示,试验中制备的催化电极可以满足大功率锌-氧电池放电时对电极透气性能的要求.     

Influence of PTFE on electrode structure for performance of PEMFC and 10-cells stack

Water plays a critical role on the performance, stability and lifetime of proton exchange membrane fuel cells(PEMFCs). The addition of poly tetrafluoroethylene(PTFE) to the gas diffusion layer, especially, the cathode side, would optimize the transportation of water, electron and gas and thus improve the performance of the fuel cell. But until now, the studies about directly applying the PTFE to the catalyst layer are rarely reported. In this paper, the membrane electrode is fabricated by using directly coating catalyst to the membrane method(CCM) and applying PTFE directly to the cathode electrode catalyst layer. The performance of the single cell is determined by polarization curves and durability tests. Electrochemical impedance spectroscopy(EIS) and scanning electron microscopy(SEM) techniques are used to characterize the electrochemical properties of PEMFC. Also the performance of a 10-cells stack is detected. Combining the performance and the physical-chemistry characterization of PEMFC shows that addition of appropriate content of PTFE to the electrode enhances the performance of the fuel cell, which may be due to the improved water management. Addition of appropriate content of PTFE enhances the interaction between the membrane and the catalyst layer, and bigger pores and highly textured structure form in the MEA, which favors the oxygen mass transfer and protons transfer in the fuel cell. While superfluous addition of PTFE covers the surface of catalysts and hindered the contact of catalyst with Nafion, which leads to the reduction of electrochemical active area and the decay of the fuel cell performance. The proposed research would optimize the water management of the fuel cell and thus improve the performance of the fuel cell.     

四氟乙烯基可熔融加工全氟聚合物研究进展

聚四氟乙烯(PTFE)因具有独特的物理化学性质,已成为不可缺少的一类特种材料。由于聚四氟乙烯的分子量和分子链规整度较高,使聚四氟乙烯难于熔融加工。为了获得可熔融加工的全氟材料,国内外关于聚四氟乙烯共聚改性的相关研究和报道较多。本文从可熔融加工四氟乙烯基全氟聚合物的结构和特性方面入手,综述了国内外一系列四氟乙烯与全氟第二单体共聚物的最新研究现状,并提出了全氟聚合物今后的研究发展方向。