Molecular Analysis of Structural Effect of Ionomer on Oxygen Permeation Properties in PEFC
Molecular Analysis of Structural Effect of Ionomer on Oxygen Permeation Properties in PEFC
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DOI：
10.1149/2.1301706jes
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发表时间：
2017-01-01
影响因子：
3.9
通讯作者：
Tokumasu, Takashi
中科院分区：
文献类型：
--
作者：
Kurihara, Yuya;Mabuchi, Takuya;Tokumasu, Takashi
采用分子动力学模拟方法分析了离聚物的结构性质和离聚物在Pt表面的透氧性能与水含量的关系。根据离聚物的密度分布定义了离聚物/气体界面、本体区域和离聚物/Pt界面。在离聚物/Pt界面中清楚地观察到氧通路相当长的一段时间。结果发现，氧气渗透性随着水含量的增加而降低，这与Nafion膜中发生的情况相反。然后分析了各个区域的氧扩散率、溶解度和渗透率。结果发现，在离聚物/Pt界面中的氧渗透性在离聚物中的氧渗透性中占主导地位。此外，氧溶解度的降低对氧渗透性的水含量依赖性具有较大的影响。考虑到离聚物的结构特性，在离聚物/Pt界面中的氧溶解度降低，因为在较高的水含量下空隙被堵塞。(C)2017年电化学学会。All rights reserved.
Molecular dynamics simulations were performed to analyze the water content dependence of the structural properties of ionomer and the oxygen permeation properties in ionomer on a Pt surface. The ionomer/gas interface, bulk region, and ionomer/Pt interface were defined based on the density distribution of ionomer. Oxygen pathways are clearly observed in the ionomer/Pt interface for quite a long period. It was found that the oxygen permeability decreases with increasing water content, which is the opposite of what takes place in the Nafion membranes. Then the oxygen diffusivity, solubility, and permeability in each region were analyzed. It was found that the oxygen permeability in the ionomer/Pt interface was dominant in the oxygen permeability in the ionomer. Furthermore, a decrease in the oxygen solubility has a larger effect on the water content dependence of oxygen permeability. Considering the structural properties of the ionomer, the oxygen solubility in the ionomer/Pt interface decreased because the voids were blocked at higher water content. (C) 2017 The Electrochemical Society. All rights reserved.