Influence of casting substrate on bulk morphology and vanadium ion transport in ionomer nanocomposites
Influence of casting substrate on bulk morphology and vanadium ion transport in ionomer nanocomposites
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DOI：
10.1063/1.5144204
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发表时间：
2020-05
影响因子：
3.2
通讯作者：
Allison Domhoff;E. Davis
中科院分区：
文献类型：
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作者：
Allison Domhoff;E. Davis
全氟磺酸（PFSA）离聚物纳米复合材料是一个有前途的解决方案，以解决目前的钒氧化还原液流电池中使用的膜的离子选择性差。在本文中，我们研究了浇铸基底对本体离聚物和离聚物纳米复合膜中的纳米结构和钒离子传输的影响（即，厚度为100 μm的薄膜）。具体地，通过在抛光的石英或聚四氟乙烯（PTFE）基底上浇铸来制造含有未官能化（羟基）、胺官能化或磺酸官能化的二氧化硅纳米颗粒（SiNP）的溶液浇铸离聚物纳米复合材料膜。令人惊讶的是，浇铸基材的选择被认为会影响PFSA离聚物的本体形态，导致基材特异性的钒离子传输，其中当与它们的PTFE浇铸对应物相比时，对于浇铸在抛光石英上的膜观察到抑制的离子传输。此外，与衬底相邻的表面的化学组成是衬底和SiNP的表面官能度两者的函数。此外，据观察，无论是膜表面的化学组成和基板诱导的变化，以散装离聚物形态支配钒氧离子运输通过PFSA离聚物。这项工作的结果对下一代离聚物纳米复合材料的设计有直接的影响，因为用于制造这些材料的铸造基材以及这些膜在工作液流电池内部的取向可以显着影响钒离子的传输。
Perfluorosulfonic acid (PFSA) ionomer nanocomposites are a promising solution to address the poor ion selectivity of current membranes utilized in vanadium redox flow batteries. Herein, we investigate the impact of a casting substrate on the nanostructure and vanadium ion transport in bulk ionomer and ionomer nanocomposite membranes (i.e., films with thicknesses of ∼100 μm). Specifically, solution-cast ionomer nanocomposite membranes, containing either unfunctionalized (hydroxyl groups), amine-functionalized, or sulfonic acid-functionalized silica nanoparticles (SiNPs), were fabricated by casting on either a polished quartz or polytetrafluoroethylene (PTFE) substrates. Surprisingly, the choice of the casting substrate was seen to affect the bulk morphology of the PFSA ionomers, resulting in substrate-specific vanadium ion transport, where suppressed ion transport was observed for membranes cast on the polished quartz, when compared to their PTFE-cast counterparts. Additionally, the chemical composition of the substrate-adjacent surface was a function of both the substrate and the surface functionality of the SiNPs. Moreover, it was observed that both the chemical composition of the membrane surface and the substrate-induced changes to the bulk ionomer morphology governed vanadyl ion transport through the PFSA ionomers. Results from this work have direct implications for the design of next-generation ionomer nanocomposites, as the casting substrate used to fabricate these materials, and the orientation of these membranes inside the operating flow battery, can significantly influence transport of vanadium ions.