Anhydrous proton-conducting polymeric electrolytes for fuel cells.
Anhydrous proton-conducting polymeric electrolytes for fuel cells.
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DOI：
10.1021/jp054167w
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发表时间：
2006-02
期刊：
影响因子：
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通讯作者：
S. Narayanan;S. Yen;L. Liu;S. Greenbaum
中科院分区：
文献类型：
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作者：
S. Narayanan;S. Yen;L. Liu;S. Greenbaum
为120摄氏度及以上的温度运行的燃料电池设计质子导电电解质的需要促使了对各种不含水的聚合物材料的研究。本文研究了由高相对分子质量的聚合物有机胺盐制备的“无水”质子导电膜的性能。具体地说，研究了聚-2-乙烯基吡啶(P2VP)、聚-4-乙烯基吡啶(P4VP)和聚乙烯基咪唑啉(PVI)的硫酸盐和二氢磷酸盐在25-180℃的温度范围内的性质，并研究了这些聚合物有机胺盐和羟化二氧化硅的纳米复合材料。这些聚合物被发现在高达200摄氏度的温度下是稳定的和质子导电的。在这里研究的所有聚合物实例中，磷酸盐比硫酸氢盐的导电性更强。离子传导的活化能随着温度的升高而减小，这与聚合物迁移率的增加和质子的电离有关。在质子核磁共振实验中观察到的高度运动变窄证实了这一点。聚合物有机胺和无机酸的电导率测量值与pKa值的差值具有明显的相关性。这一观察结果为设计其他具有增强质子导电性的无水酸碱聚合物体系提供了依据。结果表明，基于酸碱聚合物盐的无水聚合物体系可以与纳米二氧化硅等短程质子导体相结合，在整个温度范围内获得可接受的导电性。
The need to design proton-conducting electrolytes for fuel cells operating at temperatures of 120 degrees C and above has prompted the investigation of various "water-free" polymeric materials. The present study investigates the properties of "water-free" proton-conducting membranes prepared from high-molecular-weight polymeric organic amine salts. Specifically, the properties of bisulfates and dihydrogenphosphates of poly-2-vinylpyridine (P2VP), poly-4-vinylpyridine (P4VP), and polyvinylimidazoline (PVI) have been investigated over the temperature range of 25-180 degrees C. Nanocomposites of these polymeric organic amine salts and hydroxylated silica have also been investigated in this study. These polymers are found to be stable and proton-conducting at temperatures up to 200 degrees C. In all the polymer examples studied herein, the phosphates are more conducting than the bisulfates. The activation energy for ionic conduction was found to decrease with increasing temperature, and this is associated with the increased polymer mobility and ionization of the proton. This is confirmed by the high degree of motional narrowing that is observed in proton NMR experiments. The measured values of conductivity and the differences in pKa values of the polymeric organic amine and the mineral acid are clearly correlated. This observation provides the basis for the design of other water-free acid-base polymer systems with enhanced proton conductivity. The results presented here suggest that anhydrous polymer systems based on acid-base polymer salts could be combined with short-range proton conductors such as nanoparticulate silica to achieve acceptable conductivity over the entire temperature range.