Short-side-chain proton conducting perfluorosulfonic acid ionomers: Why they perform better in PEM fuel cells
Short-side-chain proton conducting perfluorosulfonic acid ionomers: Why they perform better in PEM fuel cells
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DOI：
10.1016/j.jpowsour.2007.11.011
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发表时间：
2008-04-01
影响因子：
9.2
通讯作者：
Maier, J.
中科院分区：
文献类型：
--
作者：
Kreuer, K. D.;Schuster, M.;Maier, J.
具有不同离子交换能力的短侧链（SSC）全氟磺酸离聚体IEC （Dow 840和Dow 1150）的吸水性、输运性（质子电导率、电渗透水阻力和水扩散）、微观结构和粘弹性性能作为温度和水化程度的函数进行了表征。将这些数据与nationa117 （nationa1100）的数据进行了比较，并讨论了在直接甲醇燃料电池和氢燃料电池中使用这些离子单体作为分离材料的意义。为此，使用了一种方案，该方案允许在瞬态和稳态条件下模拟水分布和由此产生的溶剂（水、甲醇）通量和跨膜的潜在损失。在直接甲醇燃料电池中，低溶剂（水、甲醇）通过Dow 1150的传输本质上是减少膨胀的结果。与Nation 117相比，道琼斯840指数中氢燃料电池的潜在损失较小，主要是由于载流子浓度较高。目前的比较表明，将高IEC与高机械稳定性结合起来，例如通过增加结晶度，或通过增加分子量，交联或引入相互作用的粒子，可以增加质子电导率和降低水的电渗透阻力。在Nation 117开始表现出塑性变形的条件下，提高的稳定性也有望保持膜/电极界面的形态。因此，这可能是一种改善直接甲醇和PEM燃料电池膜性能的合适方法。(C) 2007 Elsevier B.V.版权所有
Short-side-chain (SSC) perfluorosulfonic acid ionomers of different ion exchange capacity, IEC, (Dow 840 and Dow 1150) are characterized with respect to water sorption, transport (proton conductivity, electroosmotic water drag and water diffusion), microstructure and visco-elastic properties as a function of temperature and degree of hydration. The data are compared to those of Nafion 117 (Nation 1100), and the implications for the use of such ionomers as separator materials in direct methanol and hydrogen fuel cells are discussed. For this purpose, a scheme is used which allows for the simulation of the water distribution and the resulting solvent (water, methanol) fluxes and potential losses across the membranes under transient and steady state conditions. The lower solvent (water, methanol) transport across Dow 1150 in direct methanol fuel cells is essentially the result of the reduced swelling. The smaller potential losses across Dow 840 compared to Nation 117 in hydrogen fuel cells is mainly the result of the higher charge carrier concentration. The present comparison demonstrates that combining high IEC with high mechanical stability, e.g. by increasing crystallinity as in the present case, or by increasing molecular weight, cross-linking or introducing interacting particles, results in an increase in proton conductivity and lower electroosmotic drag of water. The improved stability is also anticipated to preserve the morphology of the membrane/electrode interface under conditions at which Nation 117 starts to show plastic deformation. Hence, this may prove to be a suitable approach to improve membrane performance in both direct methanol and PEM fuel cells. (C) 2007 Elsevier B.V. All rights reserved.