金属有机膦酸化合物和高分子材料质子导电性质的研究

发布时间：2018-12-08 21:04

【摘要】：质子交换膜燃料电池是燃料电池的一种,它的电解质材料由质子交换膜组成。这类电池的电解质材料直接决定了电池性能,拥有高导电率和高稳定性的质子交换膜能够制备性能优异的燃料电池。目前采用的材料体系主要分为聚合物和金属有机骨架化合物两类,它们各有优缺点。聚合物往往拥有很好的柔软度,化学稳定性以及可加工性,但是却有制作成本高昂,易水解等缺点。金属有机骨架化合物具有良好的结晶度、规则排列的空隙、可修饰的孔道等特点,但在成膜方面却是一个难题。基于以上描述的情况,人们考虑将二者杂化,从而产生能够融合二者优点的新材料,这就是混合基质膜。本文中我们首先按照已报道的CoCa·nH2O化合物的合成方法制备了系列化合物CoMg · nH2O、CoSr · 2H20和CoBa。其中CoMg·nH20导电率最高,被选中作为掺杂的化合物。同时,CoCa·nH20和CoMg · nH20是同构的,所以CoCa · nH20也被选取做对比。CoCa·nH20和CoMg·nH20被掺杂进Nafion、PVP、PVA和PEG几个高分子中,制备混合基质膜并进行质子导电性质的测量和分析。为了更好的融合样品,本文采用的化合物为层状物,杂化的方法采用浇铸法。具体内容如下:采用和CoCa ·nH20类似的实验方法,制备CoMg·nH2O、CoSr·2H2O和CoBa化合物。然后使用压片模具,将多晶粉末压制成样品片,使用金胶和金线将样品连接到样品夹具上,采用四电极法测量阻抗谱。测试结果表明,由于Mg2+具有更高的Lewis酸性,与Mg2+离子配位的水分子被很好的活化了,有效提高了材料中质子载流子的浓度。并且CoCa · nH20和CoMg · nH2O都拥有很高的活化能,使得ClO4-能够转动,促进质子传导。将CoCa · nH20和CoMg · nH2O按照一定质量比分别加入一定量Nafion中,超声分散混合,然后用吸管吸取分散溶液滴在基底片上,等待溶液铺开并且溶剂挥发干,再滴加,如此反复即成膜。制备的膜按照先前的描述制成测试样品进行导电测试。然后,选取PVP和PVA与等量的CoCa·nH2O融合并制备成膜(融合与制备方法同上)测试质子导电性。由于PEG成膜后非常脆,故超声完毕后选取压片方式成膜,而不采用浇铸法,其余步骤一样。结果表明,对于Nafion,配合物组分的比例越低,复合材料的导电性质越接近纯Nafion的导电性质。当配合物组分与Nafion的质量比为0.5:1时,CoMg复合材料的导电性能仅略高于CoMg·nH2O纯样。而CoCa复合材料的导电性能却比CoMg·nH2O纯样提升一个数量级。在CoCa·nH2O与不同高分子基质复合的体系中,CoCa@PEG具有最优的质子导电性能。
[Abstract]:Proton exchange membrane fuel cell is a kind of fuel cell, its electrolyte material is made up of proton exchange membrane. The electrolyte material of this kind of battery directly determines the performance of the battery. Proton exchange membrane with high conductivity and high stability can be used to prepare fuel cell with excellent performance. At present, the material systems are mainly divided into polymer and organometallic skeleton compounds, which have their own advantages and disadvantages. Polymers often have good softness, chemical stability and processability, but they have the disadvantages of high cost and easy hydrolysis. Organometallic skeleton compounds have good crystallinity, regular arrangement of voids and modifiable pores, but they are a difficult problem in film formation. Based on the situation described above, hybrid materials are considered to produce new materials which can integrate the advantages of the two materials, which is called mixed matrix membrane. In this paper, we first prepared a series of CoMg nH2O,CoSr 2H20 and CoBa. compounds according to the reported synthesis method of CoCa nH2O compounds. Among them, CoMg nH20 has the highest conductivity and is chosen as the doped compound. At the same time, CoCa nH20 and CoMg nH20 are isomorphic, so CoCa nH20 is also selected for comparison. CoCa nH20 and CoMg nH20 are doped into Nafion,PVP,PVA and PEG to prepare the mixed matrix membrane and the proton conductivity is measured and analyzed. In order to better fuse the sample, the compound used in this paper is laminar, and the hybrid method is cast. The main contents are as follows: CoMg nH2O,CoSr 2H2O and CoBa compounds were prepared by using the same experimental method as CoCa nH20. Then the polycrystalline powder was pressed into a sample sheet by pressing the die, and the sample was connected to the sample fixture by gold glue and gold wire, and the impedance spectrum was measured by four-electrode method. The results show that because of the higher Lewis acidity of Mg2, the water molecules coordinated with Mg2 ions are well activated, which effectively increases the concentration of proton carriers in the materials. And both CoCa nH20 and CoMg nH2O have high activation energies, enabling ClO4- to rotate and promote proton conduction. The CoCa nH20 and CoMg nH2O were added to a certain amount of Nafion according to certain mass ratio, then the ultrasonic dispersion was mixed, then the dispersed solution was dripped on the substrate with a suction tube, waiting for the solution to spread out and the solvent volatilized dry, then the film was formed again and again. The prepared films were prepared to test the electrical conductivity of the samples as described earlier. Then, the PVP and PVA were selected to fuse with the same amount of CoCa nH2O and the film was prepared (fusion and preparation method was used above) to test the proton conductivity. Because PEG is very brittle after film forming, the pressing method is chosen after ultrasonic forming, and the other steps are the same. The results show that the lower the proportion of Nafion, complex is, the closer the conductive properties of the composites are to those of pure Nafion. When the mass ratio of the complexes to Nafion is 0.5: 1, the electrical conductivity of the CoMg composites is only slightly higher than that of the pure CoMg nH2O samples. The conductivity of CoCa composites is one order of magnitude higher than that of CoMg nH2O. In the system of CoCa nH2O and different polymer matrix, CoCa@PEG has the best proton conductivity.
【学位授予单位】：南京大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O627.51;O631.23

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