LDH掺杂磺化聚醚醚酮复合质子交换膜的制备与表征

发布时间：2018-06-24 05:04

本文选题：直接甲醇燃料电池 + 质子交换膜　；参考：《哈尔滨工业大学》2014年硕士论文

【摘要】：质子交换膜燃料电池(PEMFC),因其具有能量转换效率高、功率密度高、低温操作和启动迅速等优点,被认为是最有前途的能量转换装置。其中,质子交换膜被公认为是直接甲醇燃料电池的核心部件。美国Du Pont公司生产的商业化Nafion质子交换膜已得到了应用,但因其具有较高的甲醇渗透率以及价格昂贵等缺点限制了其进一步的发展。因此需要探索研究成本低廉、性能较高的Nafion替代膜。聚醚醚酮(PEEK)的价格低廉,并且其性能优良。将PEEK磺化后得到SPEEK膜,该膜继承了PEEK良好的稳定性,同时具有较高的电导率,所以被认为是最有可能替代Nafion膜应用于DMFC的膜材料。但是相对于Nafion膜,SPEEK膜的质子电导率较低,并且提高SPEEK膜的电导率就必须要提高SPEEK膜的磺化度,磺化度的升高会带来膜的过度溶胀丧失机械性能。为平衡电导率和溶胀则需要对SPEEK膜进行改性。本课题制备合成了三种类型的层状双氢氧化物(LDH),它们因为层间阴离子类型不同导致层间距不同,掺杂到SPEEK中以期降低复合膜的甲醇渗透率并提高质子电导率。首先本实验合成了CO3-LDH、直接型SO4-LDH以及间接型SO4-LDH,并运用XRD、SEM、EDS、FTIR、TGA/DSC对其进行表征,分析异同点。同时合成了两种磺化度的SPEEK。本课题的最后阶段将性能良好的CO3-LDH、直接型SO4-LDH以及间接型SO4-LDH按2.5wt%、5wt%、7.5wt%和10wt%的比例分别掺杂到不同磺化度的SPEEK膜中,用重铸法制备了LDH/SPEEK复合膜。然后运用SEM、EDS、TGA/DSC、甲醇溶胀度、甲醇渗透以及质子传导等对复合膜进行表征。结果表明,三种类型的LDH,层间距越大,改性复合膜的吸水率、离子交换容量、质子电导率越好,当掺杂量为7.5%时达到最大值。高的SPEEK磺化度,复合膜的质子电导率越高,但其甲醇溶胀度和甲醇渗透率也较大。当掺杂7.5%的直接型SO4-LDH改性高磺化度SPEEK膜时,其电导率达到81.1 m S cm-1可以和Nafion115膜相媲美,选择性较纯SPEEK膜提高2倍,并且要优于Nafion115膜。
[Abstract]:Proton exchange membrane fuel cell (PEMFC) is considered as the most promising energy conversion device due to its high energy conversion efficiency, high power density, low temperature operation and rapid start-up. Among them, proton exchange membrane is recognized as the core component of direct methanol fuel cell. The commercial Nafion proton exchange membrane produced by du Pont has been applied, but its further development is limited by its high methanol permeability and high price. Therefore, it is necessary to explore the Nafion substitute membrane with low cost and high performance. The price of polyether ether ketone (peek) is low and its performance is good. After sulfonation of peek, Speek membrane was obtained, which inherits the good stability of peek and has high conductivity, so it is considered to be the most likely substitute for Nafion membrane to be used in DMFC. However, compared with Nafion membrane, the proton conductivity of Speek membrane is relatively low, and it is necessary to increase the sulfonation degree of Speek membrane to increase the conductivity of SPEEK membrane. The increase of sulfonation degree will lead to excessive swelling loss of mechanical properties of SPEEK membrane. In order to balance conductivity and swelling, it is necessary to modify Speek film. Three kinds of layered double hydroxides (LDH) were prepared and synthesized in this paper. They were doped into Speek in order to reduce methanol permeability and increase proton conductivity due to the different types of anions between layers. In this experiment, CO _ 3-LDH, direct so _ 4-LDH and indirect so _ 4-LDH were synthesized and characterized by means of XRDX SEMS-EDS-FTIR TGA / DSC, and their similarities and differences were analyzed. At the same time, two kinds of sulfonation degree Speek were synthesized. In the last stage of this project, the fine CO _ 3-LDH, direct so _ 4-LDH and indirect so _ 4-LDH were doped into the SPEEK films with different sulfonation degrees at the ratio of 2.5 wt% and 7.5 wt% and 10 wt%, respectively. The LDH / Speek composite films were prepared by recasting method. Then the composite membranes were characterized by SEMMA-EDS- TGA / DSC, methanol swelling degree, methanol permeation and proton conduction. The results show that the larger the interlayer spacing of the three types of LDH, the better the water absorption, ion exchange capacity and proton conductivity of the modified composite membrane, and the maximum value is obtained when the doping amount is 7.5. The higher the sulfonation degree of Speek, the higher the proton conductivity of the composite membrane, but the higher the methanol swelling degree and the methanol permeability. When modified with 7.5% direct SO4-LDH, the conductivity of SPEEK film with high sulfonation degree is 81.1 m S cm-1, which is comparable to Nafion 115 film, and the selectivity is 2 times higher than that of pure SPEEK film, and is better than Nafion 115 film.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM911.4

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