Park Jun Woo, Wycisk Ryszard, Pintauro Peter N, Yarlagadda Venkata, Van Nguyen Trung
Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN 37235, USA.
Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, KS 66045, USA.
Materials (Basel). 2016 Feb 29;9(3):143. doi: 10.3390/ma9030143.
The regenerative H₂/Br₂-HBr fuel cell, utilizing an oxidant solution of Br₂ in aqueous HBr, shows a number of benefits for grid-scale electricity storage. The membrane-electrode assembly, a key component of a fuel cell, contains a proton-conducting membrane, typically based on the perfluorosulfonic acid (PFSA) ionomer. Unfortunately, the high cost of PFSA membranes and their relatively high bromine crossover are serious drawbacks. Nanofiber composite membranes can overcome these limitations. In this work, composite membranes were prepared from electrospun dual-fiber mats containing Nafion PFSA ionomer for facile proton transport and an uncharged polymer, polyphenylsulfone (PPSU), for mechanical reinforcement, and swelling control. After electrospinning, Nafion/PPSU mats were converted into composite membranes by softening the PPSU fibers, through exposure to chloroform vapor, thus filling the voids between ionomer nanofibers. It was demonstrated that the relative membrane selectivity, referenced to Nafion 115, increased with increasing PPSU content, e.g., a selectivity of 11 at 25 vol% of Nafion fibers. H₂-Br₂ fuel cell power output with a 65 μm thick membrane containing 55 vol% Nafion fibers was somewhat better than that of a 150 μm Nafion 115 reference, but its cost advantage due to a four-fold decrease in PFSA content and a lower bromine species crossover make it an attractive candidate for use in H₂/Br₂-HBr systems.
再生式H₂/Br₂-HBr燃料电池利用溴在氢溴酸水溶液中的氧化剂溶液，在电网规模的电力存储方面展现出诸多优势。膜电极组件作为燃料电池的关键部件，包含一种质子传导膜，通常基于全氟磺酸（PFSA）离聚物。不幸的是，PFSA膜的高成本及其相对较高的溴渗透是严重的缺点。纳米纤维复合膜可以克服这些限制。在这项工作中，复合膜由静电纺丝双纤维垫制备而成，其中含有用于质子便捷传输的Nafion PFSA离聚物和用于机械增强及溶胀控制的不带电聚合物聚亚苯基砜（PPSU）。静电纺丝后，通过将PPSU纤维暴露于氯仿蒸汽中使其软化，从而填充离聚物纳米纤维之间的空隙，将Nafion/PPSU垫转化为复合膜。结果表明，相对于Nafion 115，膜的相对选择性随PPSU含量的增加而提高，例如，在Nafion纤维含量为25体积%时选择性为11。含有55体积% Nafion纤维的65μm厚膜的H₂-Br₂燃料电池功率输出略优于150μm厚的Nafion 115参比膜，但其由于PFSA含量降低四倍以及溴物种渗透更低而具有的成本优势，使其成为用于H₂/Br₂-HBr系统的有吸引力的候选材料。
