Membrane crystallinity and fuel crossover in direct ethanol fuel cells with Nafion composite membranes containing phosphotungstic acid

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• 作者：Hongjun Kim ; Sunghwan Lee ; Suran Kim ; Chungik Oh…
• 刊名：Journal of Materials Science
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：52
• 期：5
• 页码：2400-2412
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Materials Science, general; Characterization and Evaluation of Materials; Polymer Sciences; Continuum Mechanics and Mechanics of Materials; Crystallography and Scattering Methods; Classical Mechanics;
• 出版者：Springer US
• ISSN：1573-4803
• 卷排序：52

文摘

We report on the effect of the addition of phosphotungstic acid (PWA) in Nafion membrane on ethanol-crossover and the proton conductivity for DEFC application. A set of PWA–Nafion composite membranes (PWA 0, 5, 10, 15, 20 wt%) was prepared by solution casting and their microstructures, diffraction patterns, permeability, and proton conductivity were systematically characterized. The significant reduction in ethanol-crossover is observed with increasing PWA concentration in PWA–Nafion membranes, which is mainly attributed to an improvement in crystallinity of the membrane. PWA provides additional nucleation sites during solidification leading to higher crystallinity, which is supported by the membrane permeability tests. The proton conductivity of the composites is enhanced with PWA concentration until 15 wt% due to an increase in hopping pathways, while higher PWA of 20 wt% leads to a conductivity decrease possibly due to the excessive particle aggregations that limit ion transports. These PWA–Nafion composites were implemented in prototype DEFC devices as a membrane and the maximum power density achieved was 22% higher than that of commercial Nafion-117 device.