直接甲醇燃料电池填充型复合质子交换膜的制备与性能研究

发布时间：2018-01-24 18:12

本文关键词： 燃料电池孔填充甲醇渗透环氧树脂质子交换膜纳米纤维静电纺丝复合膜直接甲醇燃料电池　出处：《吉林大学》2017年博士论文　论文类型：学位论文

【摘要】：作为一种能够将化学能转化为电能的电化学装置,直接甲醇燃料电池由于其体积小,高燃料利用率,低排放和高能量密度等特性,被认为是未来最有希望的清洁能源之一,一直以来得到研究工作者的广泛关注。质子传导膜是燃料电池的核心部件,它是一种在燃料电池中传递质子,分隔电池阳极与阴极的电解质材料。常用的质子传导膜材料包括全氟磺酸系列,磺化芳香聚合物(如磺化聚芳醚,磺化聚苯并吡唑,磺化聚酰亚胺)等。质子传导膜的质子传导率,机械稳定性,热稳定性,化学稳定性以及尺寸稳定性等性能是质子传导膜的关键数据。目前,全氟磺酸聚合物(Nafion~?)由于其高质子传导率和较为突出的综合性能成为了被最广泛使用的材料。然而全氟磺酸系列膜也存在着许多众所周知的缺陷,包括造价较高、阳极反应速率低、使用寿命有限、溶胀率高等,尤其是甲醇渗透十分严重,这些问题限制了DMFC的进一步应用。甲醇从阴极渗透到阳极会导致燃料使用效率下降,阴极催化剂中毒,以致整个电池的性能下降。为了减弱甲醇渗透带来的影响,实际应用中只能使用低于2M浓度的甲醇溶液作为燃料,大大降低了直接甲醇燃料电池的性能。考虑到水在质子传导中的作用以及燃料浓度对电池性能的影响,为了得到较高的能量密度,10M甲醇水溶液是直接甲醇燃料电池的理想燃料。因此,这种高浓度甲醇溶液的使用就要求质子传导膜具有极小的甲醇渗透率和较高的尺寸稳定性。本论文旨在制备适用于高浓度甲醇溶液中的复合质子交换膜,并分别对其机械性能,热学性能,化学稳定性,传导率和电池性能进行了研究,从而探究传导膜的不同制备方法和材料对DMFC在高浓度甲醇中的电池性能的影响。具体内容分为三部分:孔填充复合质子交换膜,静电纺丝纤维孔隙填充复合质子交换膜和多维纺丝纤维孔隙填充复合质子交换膜。这三部分内容基于同样的理念,即由机械强度高,阻醇性好的材料与高质子传导率的材料利用孔隙填充的方法制备复合质子交换膜。第一部分,我们成功制备了基于聚醚砜的孔填充质子交换膜,并对其性能进行了测试。首先合成了具有低磺化度和一定比例氨基的磺化聚醚砜(ASPES),并利用在铸膜液中引入离子液体的方法制备了ASPES多孔膜,同时研究了制备过程中离子液体的含量对多孔膜孔形貌的影响。接着我们首次合成了环氧基封端的磺化聚醚砜低聚物(DSPES)作为复合膜填充电解质,并用低聚物DSPES对ASPES多孔膜基体进行填充,固化交联,制备复合膜。由于ASPES磺酸根含量低,在水中具有良好的尺寸稳定性,因而抑制了复合膜的溶胀效应,溶胀率的降低使得聚合物分子链间作用增强,同时抑制了甲醇的渗透作用。在氨基作用下,环氧聚合物在多孔膜中交联形成三维结构,大大的提高了复合膜机械性能,从而进一步抑制了复合膜的溶胀和甲醇渗透效应。得到的复合膜同时具有优异的氧化稳定性,热稳定性和机械强度,虽然其质子传导率略低于Nafion~?,但与同类型的孔填充复合膜相比,其传导率仍然相对较高,同时,由于复合膜具有很低的甲醇渗透率,因此在传导率和甲醇渗透率之间的选择性较高,远高于Nafion~?膜。在10M甲醇溶液中,复合膜同样表现出了高于Nafion~?的单电池性能。第二部分,我们成功制备了两种PDMS和Nafion~?互为填充相的复合膜为,从纳米尺度抑制复合膜溶胀及甲醇渗透。一种为Nafion~?填充PDMS静电纺纤维复合膜,一种为PDMS填充Nafion~?静电纺丝纤维复合膜。我们对两者及Nafion~?的性能进行了测试和比较。实验中首先分别制备了PDMS和Nafion~?的纤维膜,并分别按照不同的比例使用Nafion~?溶液填充PDMS纤维膜,使用PDMS填充Nafion~?纤维膜。静电纺丝纤维和填充后的复合膜表面及截面的形貌同过扫描电镜度进行了表征。由复合膜和Nafion~?的吸水率溶胀率测试结果发现,由于疏水性PDMS的引入,复合膜的吸水溶胀率要远低于Nafion~?膜。同时复合膜的热稳定性氧化稳定性在热失重分析和芬顿试剂测试中均优于Nafion~?膜。复合膜和Nafion~?膜在10M甲醇水溶液中的电池性能同样与Nafion~?进行了比较,证明复合膜在高浓度甲醇溶液中的电池性能要高于Nafion~?膜,且Nafion~?为填充相时,复合膜电池性能性能提升幅度较大。第三部分,由上述实验可知Nafion~?为填充主体时复合膜电池性能更优,同时为了提高纤维膜的可填充充性,我们制备了以Nafion~?为填充主体的超薄的聚偏氟乙烯(PVDF)静电纺丝纤维复合膜和PVDF/PTFE混合静电纺丝纤维与Nafion的复合膜,并将其纤维层用作复合膜中甲醇的阻醇层。首先我们制备了一系列Nafion~?填充的多层静电纺丝PVDF纤维复合膜,并对其与Nafion~?膜的性能进行了测试和比较。纤维及复合膜的形貌和结构,热稳定性,机械稳定性,化学稳定性,质子传导率以及单电池性能均得到了表征。与Nafion~?膜相比,PVDF纤维膜的引入显著的增强了复合膜的热稳定性和化学稳定性,同时抑制了膜的吸水溶胀作用。复合膜在10M甲醇溶液中同时表现出了相比于Nafion~?更高的电池性能,然而复合膜的电池性能相近,并没有随着PVDF纤维膜层数的增加而升高。基于以上实验结果,我们又设计制备了单侧(阳极侧和阴极侧)具有单层PTFE/PVDF纤维阻醇层的Nafion~?115复合膜,并对其在5 M和10 M甲醇溶液中的电池性能进行了测试。测试结果表明相比于商业化的Nafion~?115膜,复合膜的电池性的得到了较大的提高,同时电池的能量密度随着PTFE在纤维中的质量分数的升高而升高,此外,PTFE/PVDF纤维膜在电池阳极侧时,电池性能要高于其在电极阴极侧时。在以上三部分实验中,分别制备了一系列的多种孔填充复合膜,包括多孔填充膜和静电纺丝纤维填充膜等。这些膜的性能在实验中得到了多方面的测试,尤其是膜在高浓度甲醇溶液中的单电池性能,测试结果表明了复合膜孔填充制备方法以及使用材料的有效性,复合膜的性能均优于Nafion~?膜,并通过不断的改进,制备的阳极单侧9%PTFE/PVDF与Nafion~?115的性能要远好于商用Nafion~?115且方法制备简单易行,不破坏商品膜的内部结构,具有重要的参考意义。
[Abstract]:As a way to convert chemical energy into electrical energy electrochemical devices, direct methanol fuel cell because of its small volume, high fuel utilization, low emission characteristics and high energy density, is considered one of the most promising future clean energy, has been widely concerned. The research work is a proton conducting membrane the core components of the fuel cell, it is a kind of proton transfer in the fuel cell, electrolyte battery anode and cathode materials separation. Proton conducting membrane materials used include perfluorinated sulfonic acid series, sulfonated aromatic polymer (such as sulfonated poly aryl ether, sulfonated polyphenylene and pyrazole, sulfonated polyimide). Proton conducting proton conducting membrane the rate of mechanical stability, thermal stability, chemical stability and dimensional stability performance is the key data of proton conducting membrane. At present, perfluorosulfonic acid polymer (Nafion~?) because of its high proton conductivity The comprehensive performance of the more prominent and become the most widely used materials. However Nafion film series also has many defects including high cost as everyone knows, the anode, the reaction rate is low, the service life is limited, the swelling rate higher, especially the methanol permeability is very serious, these problems limit the further application of DMFC from methanol. The cathode to anode penetration will lead to a decline in fuel efficiency, cathode catalyst poisoning, so the battery performance decline. In order to reduce methanol permeability caused by the practical application can be used in the lower concentration of 2M methanol as fuel, greatly reduces the performance of a direct methanol fuel cell. Considering the effect of water on proton conduction in and the fuel concentration on the performance of the battery, in order to obtain a higher energy density, 10M methanol water solution is an ideal fuel for direct methanol fuel cell. So Using this, the dimensional stability of high concentration methanol solution requires a proton conducting membrane with minimal methanol permeability and high proton. This thesis is suitable for preparation of high concentration methanol solution exchange membrane, and the mechanical properties, thermal properties, chemical stability, conductivity and cell performance were studied. Effects of different preparation methods and materials to explore the conductive film on the battery performance of DMFC in high concentration of methanol. The specific content is divided into three parts: the hole filling composite proton exchange membrane, electrospun fibers, complex pore filling alloy PEM and multidimensional spinning fiber pore filling composite proton exchange membrane. These three parts based on the same concept, namely, high mechanical strength, method of pore filling materials prepared by methanol well with high proton conductivity of composite proton exchange membrane. The first part, I We successfully prepared PES hole filling based on proton exchange membrane, and its performance was tested. The first synthesis of sulfonated polyethersulfone with low sulfonation degree and a certain proportion of amino group (ASPES), ASPES and preparation of porous membrane by means of introducing ionic liquids in casting solution were also studied. The influence of content of ionic liquid in the preparation process on the pore morphology. Then we synthesized sulfonated polyether sulfone epoxy terminated oligomer (DSPES) as the composite membrane filled with electrolyte, and the porous ASPES matrix are filled with DSPES polymer crosslinking, preparation of composite film. Because the ASPES sulfonic acid content low, has good dimensional stability in water, thus inhibiting the swelling effect of the composite membrane, reduce the swelling rate of the polymer molecular chain enhanced, while inhibiting the penetration of methanol in ammonia medium under the action of the ring Oxygen crosslinked polymer in porous film formed in the three-dimensional structure, greatly improve the mechanical properties of composite membrane, which further inhibit composite membrane swelling and methanol permeability effect. The resulting composite membrane also has excellent oxidation stability, thermal stability and mechanical strength, while the proton conductivity is slightly lower than Nafion~, but with the same type? The hole is filled with a composite film, its transmission rate is high, is still relatively at the same time, because the methanol permeability of composite membrane has very low, so in between the conductivity and methanol permeability of high selectivity, far higher than Nafion~? Membrane. In methanol solution of 10M, composite membrane also showed higher than that of Nafion~? The single cell performance. The second part, we successfully prepared two kinds of PDMS and Nafion~? Are filled composite film phase, from nano scale inhibition of composite membrane swelling and methanol permeability. A Nafion~ filled PDMS electrospun fiber? Dimensional composite film, a PDMS filled Nafion~? Electrospun fiber composite membrane. We both and Nafion~? Performance were tested and compared. In this experiment, PDMS and Nafion~ respectively were prepared? The fiber membrane, and respectively according to the ratio of Nafion~? PDMS solution filling fiber membrane, filling Nafion~ PDMS? Fiber membrane. Membrane surface and cross-section morphology of the composite fibers by electrospinning and after filling were characterized with scanning electron microscopy. The composite membrane and Nafion~? Water absorption swelling rate test results showed that due to the introduction of hydrophobic PDMS, the swelling rate of composite membrane is much lower than that of Nafion~ membrane. At the same time? The thermal stability of the oxidation stability of composite membrane in thermogravimetric analysis and Fenton reagent test was superior to Nafion~ membrane and Nafion~ membrane.?? The same with the performance of Nafion~ battery membrane in 10M methanol in aqueous solution were compared to prove that? The battery performance of membrane in high concentration methanol solution was higher than that of Nafion~ film, and Nafion~?? as the filling phase, the battery performance of composite membrane to improve greatly. The third part, the experiment shows that Nafion~ is the main performance? Filled composite membrane cell better, at the same time in order to improve can be filled with fiber membrane and we were prepared using Nafion~ as the main filling? Thin polyvinylidene fluoride (PVDF) composite membrane electrospun fiber composite membrane and PVDF/PTFE mixed electrospun fibers and Nafion, and the fiber layer is used as the methanol methanol layer in the composite film. First, we prepared a series of Nafion~ multilayer prepared? The electrospun PVDF fiber composite membrane filled, and the Nafion~? Membrane properties were tested and compared. The morphology and structure of fiber and composite membrane, thermal stability, mechanical stability, chemical stability, proton conductivity and single cell. Could have been characterized with Nafion~? Film compared to the introduction of PVDF fiber membrane significantly enhances the thermal stability of composite membranes and chemical stability, and restrain the swelling effect of membrane. The composite film in 10M methanol solution at the same time show compared to the Nafion~ battery? Higher performance, but the performance of the composite battery the film is similar, and not increased with the increasing of PVDF fiber layers. Based on the above experimental results, we designed the unilateral preparation (anode side and cathode side) with single PTFE/PVDF fiber methanol layer Nafion~? 115 composite film, and the 5 M and 10 M methanol solution in battery performance tested. Test results show that compared to the commercial Nafion~? 115 membrane, composite membrane of the cell was improved, and the energy density of the battery is increased with the increase of mass fraction of PTFE in the fiber and PTFE/PV DF fiber membrane in the anode side, the battery performance is higher than that of the cathode side. In the above three parts were prepared in the experiment, a series of multiple hole filling composite membrane comprises a porous membrane and filled electrospun fibers filled membrane. The performance of these membranes was tested in many aspects in the experiment, especially the single cell performance of membrane in high concentration methanol solution, the test results show that the composite membrane pore filling preparation method and the effectiveness of the use of materials, the performance of composite membranes were better than those of Nafion~? Film, and through continuous improvement, preparation of anode unilateral 9%PTFE/PVDF with Nafion~? 115 performance be far better than the commercial Nafion~? 115 and the preparation method is simple and easy, does not destroy the internal structure of commercial membranes, which has important reference significance.

【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TQ425.236;TM911.4

【相似文献】