Transport Property Modulation via Solvent-Specific Behavior in Crosslinked Nonaqueous Membranes
Transport Property Modulation via Solvent-Specific Behavior in Crosslinked Nonaqueous Membranes
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DOI：
10.1021/acsapm.2c02121
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发表时间：
2023-03
影响因子：
5
通讯作者：
Patrick M. McCormack;Gary M. Koenig;Geoffrey M. Geise
中科院分区：
文献类型：
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作者：
Patrick M. McCormack;Gary M. Koenig;Geoffrey M. Geise
非水氧化还原液流电池(RFB)是一种经济上很有前途的解决方案，可以在10h或更长的放电时间内满足电网规模的能量存储需求。然而，膜在非水体系中的传输特性并不像在水中那样被理解。溶剂特有的效应使理解非水体系中传输的努力复杂化。改变用来测量膜传输性能的溶剂会导致溶剂吸收的变化，这可能会掩盖其他特定于溶剂的差异和趋势。这项研究通过使用具有后交联溶剂交换步骤的交联膜来改变三种适用于RFBS的溶剂的膜溶剂吸收来解偶联这些影响。这一方法使溶剂吸收和特定测量溶剂对膜传输性质的影响的研究成为可能。结果表明，不同测量溶剂之间的聚合物溶剂化作用不同，这些差异导致了离子电导率和非带电活性物质渗透率对溶剂吸收的敏感性的变化。此外，这些敏感性的变化似乎是相互独立的，例如，对于某些材料，观察到离子电导率与溶剂吸收率的弱相关性，以及渗透率与溶剂吸收率的强相关性。因此，性能最好的膜，即以乙腈为消溶剂、以碳酸丙酯为表征材料的交联型苯氧基苯胺三磺酸功能化聚苯醚薄膜，保持了0.20ms cm-1的高电导率，同时将活性物质的渗透率限制在10-11cm2s-1以下。已报道的特定溶剂-聚合物相互作用表明，特定的溶剂-聚合物相互作用可能提供了一种同时提高离子电导率和降低活性物质渗透性的途径，这将导致更高选择性的膜，从而实现高效的非水RFB。
Nonaqueous redox flow batteries (RFBs) are one economically promising solution for meeting grid-scale energy storage needs at discharge durations of 10 h or more. However, membrane transport properties in nonaqueous systems are not as well understood as in water. Solvent-specific effects complicate efforts to understand transport in nonaqueous systems. Changing the solvent used to measure membrane transport properties causes changes in solvent uptake, which can mask other solvent-specific differences and trends. This study decoupled these effects by using crosslinked membranes with post-crosslinking solvent exchange steps to vary the membrane solvent uptake of three solvents that are suitable for RFBs. This approach enabled the independent study of solvent uptake and specific measurement solvent effects on membrane transport properties. The results revealed differences in polymer solvation between the measurement solvents, and these differences led to changes in the sensitivity of both ionic conductivity and uncharged active material permeability to solvent uptake. Additionally, these changes in sensitivity appeared to be independent of each other, e.g., a weak dependence of ionic conductivity on solvent uptake coupled with a strong dependence of permeability on solvent uptake was observed for some materials. As a result, the highest-performing membrane, a crosslinked phenoxyaniline trisulfonate-functionalized poly(phenylene oxide) membrane produced using acetonitrile as the de-swelling solvent and characterized using propylene carbonate, retained a high conductivity of 0.20 mS cm–1while restricting active material permeability to less than 10–11cm2s–1. The reported solvent-specific behavior suggests that specific solvent–polymer interactions may provide a route to simultaneously increase ionic conductivity and decrease active material permeability, which would lead to more selective membranes to enable high-efficiency nonaqueous RFBs.