质子交换膜微观结构调控研究

发布时间：2018-06-14 12:31

本文选题：质子交换膜 + 质子导电通道　；参考：《天津大学》2015年博士论文

【摘要】：质子交换膜燃料电池(PEMFC)凭借其高能量转化率、高功率密度、环境友好、室温下启动快等优点,在便携电器、分布式电站和电动汽车等方面具有广阔的应用前景。质子交换膜(PEMs)是PEMFC重要的核心部件,膜的电导率对电池性能有重要的影响。PEMs由疏水的骨架和亲水的离子簇构成,离子簇形成质子导电的通道。本研究试图通过调节膜内的微观结构在膜内构建宽畅、直通的质子通道,从而提高膜的电导率。为提高磺化聚醚醚酮(SPEEK)膜性能,我们首次将小分子凝胶模板剂3,4-二甲基苯甲醛(DMBA)引入SPEEK铸膜液内铸膜。借助DMBA在铸膜液中发生聚集形成疏水模板,促使SPEEK的主链骨架规整有序排列,并且DMBA的极性醛基诱导SPEEK磺酸基团在膜内聚集。实验结果显示,铸膜液中引入DMBA使膜内离子簇增大、抗溶胀性和抗拉强度显著提高。这为SPEEK膜高磺化度下过度溶胀、低磺化度下电导率不足的难题提供了解决途径。为提高磺化聚醚醚酮(SPEEK)膜电导率性能,我们首次采用N,N-二甲基甲酰胺(DMF)和碳酸二乙酯(DEC)的双溶剂铸膜液浇铸SPEEK膜。低极性的非溶剂DEC诱导SPEEK发生自组装,形成较大的聚合物团聚体。双溶剂浇铸的SPEEK膜电导率和吸水率明显提高。在垂直膜面方向对双溶剂铸膜液施加不同类型的电场,制备了具有定向结构的SPEEK膜。在频率f=1Hz,交流场强3500 V·cm-1时,制备的SPEEK定向膜具有最高的电导率。相比直流电场定向制膜,交流电场定向制膜可以更为显著地改善膜的性能,这归因于交流电场下消除了电泳的影响。为提高全氟磺酸Nafion膜电导率,我们首次将低极性的非溶剂对二甲苯(PX)引入到Nafion/DMF铸膜液体系中铸膜。低极性的非溶剂PX诱导Nafion发生自组装,形成不透明的铸膜液。实验结果显示,采用双溶剂铸膜液制备的Nafion膜具有较大的离子团簇,并且电导率和吸水率均有提高。通过对双溶剂铸膜液施加垂直膜面方向的交流电场,制备了具有定向结构的Nafion膜。在频率f=1Hz、交流场强4000 V·cm-1时,制备的Nafion定向膜具有最高的电导率。电场定向膜的电导率和机械性能随着电场强度增加而提高。
[Abstract]:Proton exchange membrane fuel cell (PEMFC) has wide application prospects in portable appliances, distributed power plants and electric vehicles due to its advantages of high energy conversion, high power density, environmental friendliness and fast start at room temperature. Proton exchange membrane (PEMs) is an important core component of PEMFC. The conductivity of PEMFC has an important effect on the performance of the cell. PEMs are composed of hydrophobic framework and hydrophilic ion clusters, which form the channel of proton conduction. In this study, we try to improve the conductivity of the membrane by adjusting the microstructure of the membrane to construct a wide and straight proton channel in the membrane. In order to improve the performance of sulfonated polyether ether ketone (SPEEK) membrane, we first introduced the small molecular gel template 3O4-dimethylbenzaldehyde (DMBA) into the casting solution of SPEEK film. The hydrophobic template was formed by the aggregation of DMBA in the casting solution, which promoted the ordered arrangement of main chain skeleton of Speek, and the polar aldehyde group of DMBA induced the aggregation of SPEEK sulfonic group in the membrane. The experimental results show that the introduction of DMBA into the casting solution increases the ion cluster and the swelling resistance and tensile strength. This provides a solution to the problem of excessive swelling at high sulfonation degree and insufficient conductivity at low sulfonation degree. In order to improve the electrical conductivity of sulfonated polyether ether ketone (SPEEK) membrane, we first used N- (N-dimethylformamide) (DMF) and diethyl carbonate (DEC) as casting solution to cast Speek film. Low polarity non-solvent DEC induces self-assembly of Speek to form larger polymer aggregates. The conductivity and water absorption of Speek film cast by double solvent casting were improved obviously. Speek films with directional structure were prepared by applying different types of electric field to the double solvent casting solution perpendicular to the surface of the film. The SPEEK film has the highest conductivity when the frequency is 1 Hz and the AC field is 3500 V cm-1. Compared with direct-current field-oriented films, AC field-oriented films can significantly improve the performance of the films, which is due to the elimination of electrophoretic effects under AC field. In order to improve the conductivity of perfluorosulfonic acid Nafion membrane, we introduced the low-polarity non-solvent p-xylene PX into Nafion / DMF casting solution for the first time. Low polarity non-solvent PX induces self-assembly of Nafion to form opaque casting solution. The experimental results show that the Nafion membrane prepared by double solvent casting solution has a large ionic cluster, and the conductivity and water absorption of Nafion membrane are improved. Nafion membrane with directional structure was prepared by applying an alternating electric field perpendicular to the surface of the film. The Nafion directional film has the highest conductivity when the frequency is 1 Hz and the AC field is 4000 V cm-1. The electrical conductivity and mechanical properties of the electric field oriented film increase with the increase of electric field strength.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TM911.4

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