Tuning the Perfluorosulfonic Acid Membrane Morphology for Vanadium Redox-Flow Batteries

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• 作者：M. Vijayakumar ; Qingtao Luo ; Ralph Lloyd ; Zimin Nie ; Xiaoliang Wei ; Bin Li ; Vincent Sprenkle ; J-David Londono ; Murat Unlu ; Wei Wang
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2016
• 出版时间：December 21, 2016
• 年：2016
• 卷：8
• 期：50
• 页码：34327-34334
• 全文大小：459K
• ISSN：1944-8252

文摘

The microstructure of perfluorinated sulfonic acid proton-exchange membranes such as Nafion significantly affects their transport properties and performance in a vanadium redox-flow battery (VRB). In this work, Nafion membranes with various equivalent weights ranging from 1000 to 1500 are prepared and the morphology–property–performance relationship is investigated. NMR and small-angle X-ray scattering studies revealed their composition and morphology variances, which lead to major differences in key transport properties related to proton conduction and vanadium-ion permeation. Their performances are further characterized as VRB membranes. On the basis of this understanding, a new perfluorosulfonic acid membrane is designed with optimal pore geometry and thickness, leading to higher ion selectivity and lower cost compared with the widely used Nafion 115. Excellent VRB single-cell performance (89.3% energy efficiency at 50 mA·cm^–2) was achieved along with a stable cyclical capacity over prolonged cycling.