Properties of Nafion® NR-211 membranes for PEMFCs
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- 作者：Jennifer Peron ; Ana Mani ; Xinsheng Zhao ; Dave Edwards ; Makoto Adachi ; Tatyana Soboleva ; Zhiqing Shi ; Zhong Xie ; Titichai Navessin ; Steven Holdcroft
- 关键词：Nafion® ; membrane ; Proton conductivity ; Water sorption and transport ; Oxygen permeability ; Fuel cell
- 刊名：Journal of Membrane Science
- 出版年：2010
- 出版时间：1 July 2010
- 年：2010
- 卷：356
- 期：1-2
- 页码：44-51
- 全文大小：612 K
文摘
Nafion® 211 is the membrane of reference for many fuel cell users, but the literature on its properties is sparse. Unlike previous embodiments of Nafion® membranes, which are obtained by melt extrusion, Nafion® 211 is prepared by dispersion casting. This paper reports a range of properties obtained by ex situ and in situ characterization methods. Water uptake and proton conductivity are studied as a function of temperature and relative humidity. The extent of dimensional changes of as-received membranes upon hydration is found to be independent of thermal treatment. At 25 °C and 97 % RH the maximum hydration number is 12. Absorption from liquid water and vapour are observed to be similar. Proton conductivity for Nafion® 211 is reported up 80 °C and as a function of relative humidity. At 80 °C, the conductivity increases from 0.0012 to 0.13 S/cm as RH is increased from 10 to 95 % . The hydraulic permeability of Nafion® 211 is 2.4 × 10−16 m2 Pa−1 s−1 at 70 °C and the permeance is 8.8 × 10−12 m Pa−1 s−1. Oxygen solubility and the diffusion coefficient, studied using a solid state electrochemical cell, are 1.6 × 10−5 mol cm−3 and 1.04 × 10−6 cm2 s−1 at 30 °C, 100 % RH, and 30 psi oxygen. Oxygen permeability is 1.71 × 10−11 mol cm−1 s−1 under similar conditions. In situ measurement of hydrogen crossover current is 1.2 mA/cm2 at 80 °C and 100 % RH.