Aromatic Nitrile and Ketone Polymer Electrolyte Membranes (PEM) for Fuel Cells
(0) Aromatic polyelectrolyte membrane (PEM) materials are being widely investigated as replacements for perfluorinated sulfonic acid ionomers to reduce cost and improve performance such as operating temperature in polyelectrolyte membrane fuel cells (PEMFC) and methanol crossover in the direct methanol fuel cell (DMFC)application. Some of the property requirements are thermal and chemical stability, low dimensional swelling,low methanol permeability in the case of DMFC and high proton conductivity. In comparison with Nation-type PEMs, which contains strongly acidic fluoro-sulfonic acid groups, hydrocarbon PEMs are weaker acids and generally require higher ion exchange capacities (IEC) to achieve similarly high proton conductivity. High proton conductivity, achieved by high IEC values in hydrocarbon PEMs typically lead to mechanically fragile membranes, which is the result of excessive water uptake and dimensional swelling upon hydration. This tradeoff can be alleviated by designing either high IEC PEMs where interchain interactions are enhanced (e.g. dipolar interactions) or by designing materials that may lead to phase-separated domains.Nitrile-containing PEM materials allow strong interchain interactions, which strongly inhibits water and methanol uptake, even at high IEC values. This property in the PEM material leads to improved fuel cell performance.Another design approach is to provide separation between the sulfonic acid group and the aromatic polymer backbone, which can be achieved by a rapid, site specific and mild post-sulfonation of pendant phenyl side chains, which does not result in chain degradation. This approach has been used in both polyarylene ketones and nitriles.The synthesis and properties of several types of pendant-phenyl PEMs polymers will be discussed, as well as selected fuel cell data.
MICHAEL D.GUIVER DAE SIK KIM BAIJUN LIU GILLES P.ROBERTSON YU SEUNG KIM
Institute for Chemical Process and Environmental Technology,National Research Council Canada,1200 Mo Institute for Chemical Process and Environmental Technology,National Research Council Canada,1200 Mo Materials Physics & Applications,Sensors and Electrochemical Devices Group Los Alamos National Labor
国际会议
5th International Symposium on High-Tech Polymer Materials(HTPM-V)(第五届国际高技术高分子材料学术会议)
北京
英文
63
2008-10-27（万方平台首次上网日期，不代表论文的发表时间）