面向碱性燃料电池应用的阴离子交换膜的设计与制备

发布时间：2018-06-26 11:17

本文选题：碱性聚合物燃料电池 + 阴离子交换膜　；参考：《中国科学技术大学》2015年博士论文

【摘要】：聚合物电解质膜燃料电池作为清洁的新能源,由于其具有工作温度低、启动时间短、功率密度高等特点,近年来倍受关注。通常,聚合物电解质膜燃料电池会分为两类：质子交换膜燃料电池(PEMFCs)和碱性阴离子交换膜燃料电池(AAEMFCs)。相比于广泛研究的PEMFCs, AAEMFCs具有电极反应效率高、燃料泄漏率低,特别是允许非贵金属催化剂的使用等优势,逐渐成为研究热点。阴离子交换膜作为AAEMFCs重要组成部分,它在燃料电池起到催化剂支撑体、为电极反应提供环境、隔离气体或燃料、为氢氧根提供传输通道等作用,它的性能直接决定燃料电池的性能、寿命和效率。但对于阴离子交换膜,目前尚未出现如质子交换膜中的全氟磺酸膜(Nafion)综合性能优异的膜。氢氧根电导率低、尺寸稳定性和碱性稳定性差是现有阴膜中普遍存在的问题,极大地限制了AAEMFCs的发展。因此,开发高氢氧根电导率、高碱性稳定性的阴离子交换膜材料,对AAEMFC的发展和实际应用具有重大意义。 Nafion膜的微观结构-性能之间的研究表明,在膜体系内构建贯穿的离子通道是提高离子膜电导率的重要途径。因此,设计具有传导氢氧根能力的接枝型聚合物,可以通过自组装来构建贯穿离子通道,从而可以获得高氢氧根电导率的阴离子交换膜。另一方面,为了解决阴离子交换膜的耐碱性挑战,有必要设计新型的碱性功能基团。在这一背景下,本文主要研究内容如下： (1)以聚偏氟乙烯(PVDF)为主体,使用原子转移自由基聚合(ATRP)制备的接枝型阴离子交换膜,由于具有一定的相分离,所获得膜氢氧根电导率性能较为优异。此外,由于主链PVDF具有一定的结晶性能,膜的机械性能和热性能也尤为优异。 (2)以溴化聚苯醚(BPPO)为主体,使用电子转移再生催化剂原子转移自由基聚合(ARGET ATRP)制备梳型的阴离子交换膜。梳型结构具有高的接枝密度和低的接枝长度,可以形成理想的相分离形貌,因而膜的氢氧根电导率性能优异,80℃下高达100mS/cm。然而,其它燃料电池相关性能仍需要进一步优化。 (3)在研究(2)基础上,对接枝聚合物结构参数进一步优化。选用低溴化度的聚苯醚(PPO),并对催化剂用量进行优化,制备低接枝密度、高接枝长度的Rod-Coil型阴离子交换膜。Rod-Coil型阴离子交换膜不仅能够完成理想的微观相分离,获得优异的氢氧根传导性能,90℃下电导率高达198mS/cm。Rod-Coil型阴离子交换膜由于接枝密度较低的特点,侧链对主链的影响小,还可以实现对膜的耐碱性能的提高。这个研究实现了从大分子结构设计的角度,同时实现了氢氧根电导率和耐碱性能的提高。这个研究也提供了一个制备优异阴离子交换膜的新思路。 (4)在阴离子交换膜中引入交联结构可以有效抑制膜的溶胀、提高膜的耐碱性能和热稳定性。然而,交联会阻隔膜内的离子通道,降低膜的氢氧根电导率。通过选用与接枝型阴离子交换膜主链具有相同组成的大分子交联剂(BPPO),不仅可以实现有效的交联,而且可以不破坏离子膜内相分离形貌。所制备的膜实现提高膜稳定性的同时,不降低膜的氢氧根电导率。这个研究提供了一个在膜体系内设计合理交联结构的新思路。 (5)选用1-甲基咪唑(MIm)对溴化聚苯醚(BPPO)进行碱性功能化,制备咪唑型阴离子交换膜。由于咪唑环的五元杂环结构和π共轭结构的存在,可以有效阻挡氢氧根对其进攻。并且,咪唑的独有的结构可以在高温下表现出较强的热稳定性。所以,咪唑型阴离子交换膜的耐碱性能和热稳定性能相比于传统的季铵型阴离子交换膜都有所提高。咪唑型膜的单电池输出功率为30mW/cm2.
[Abstract]:As a new clean energy, polymer electrolyte membrane fuel cell has attracted much attention in recent years because of its low working temperature, short start time and high power density. Usually, polymer electrolyte membrane fuel cells will be divided into two types: proton exchange membrane fuel cell (PEMFCs) and alkaline anion exchange membrane fuel cell (AAEMFCs). Compared to the widely studied PEMFCs, AAEMFCs has the advantages of high efficiency of electrode reaction, low fuel leakage rate, especially the use of non noble metal catalysts, and has gradually become a hot spot. As an important component of AAEMFCs, anionic exchange membrane plays a catalyst support in fuel cell, provides an environment for electrode reaction, isolating gas or Fuel, which provides a transmission channel for hydroxyl, its performance directly determines the performance, life and efficiency of the fuel cell. But for the anion exchange membrane, there has not been a membrane with excellent comprehensive performance, such as the perfluoro sulfonic membrane (Nafion) in the proton exchange membrane. The low conductivity of hydroxyl, the poor dimensional stability and poor basic stability are the existing negative factors. The widespread problems in the membrane greatly restrict the development of AAEMFCs. Therefore, the development of the anion exchange membrane materials with high hydrogen oxygen root conductivity and high alkaline stability is of great significance to the development and practical application of AAEMFC.
The study of the microstructure and properties of the Nafion film shows that the construction of the ion channel in the membrane system is an important way to improve the conductivity of the ionic membrane. Therefore, the design of the graft polymer with the ability to conduct the hydroxyl radicals can be constructed through self-assembly, and the conductivity of the high hydroxyl radicals can be obtained. On the other hand, in order to solve the alkali resistance challenge of the anion exchange membrane, it is necessary to design new basic functional groups. In this context, the main contents of this paper are as follows:
(1) the grafting type anion exchange membrane prepared with polyvinylidene fluoride (PVDF) and atomic transfer radical polymerization (ATRP) has excellent electrical conductivity performance because of a certain phase separation. In addition, the mechanical and thermal properties of the membrane are particularly excellent because the main chain PVDF has a certain nodal properties.
(2) with brominated polyphenyl ether (BPPO) as the main body, the comb type anion exchange membrane is prepared by electron transfer regeneration catalyst atom transfer free radical polymerization (ARGET ATRP). The comb structure has high grafting density and low grafting length, which can form ideal phase separation morphology. Therefore, the conductivity of hydroxyl radicals of the membrane is excellent and is up to 100m at 80. S/cm. however, other fuel cell performance needs to be further optimized.
(3) on the basis of the study (2), the structural parameters of the graft polymer were further optimized. The low brominated polyphenylene ether (PPO) was selected and the amount of the catalyst was optimized to prepare the Rod-Coil anion exchange membrane.Rod-Coil anion exchange membrane with low grafting density and high grafting length, which not only can complete the ideal microscopic phase separation, but also obtain excellent results. With the conductivity of hydroxyl, the conductivity of the 198mS/cm.Rod-Coil type anion exchange membrane at 90 degrees centigrade is low because of the low density of the graft. The side chain has little influence on the main chain, and it can also improve the alkali resistance of the membrane. This study realized the electrical conductivity and alkali resistance of the hydroxyl group at the angle of the design of the macromolecular structure. This study also provides a new idea for preparing excellent anion exchange membrane.
(4) the introduction of crosslinking structure in the anion exchange membrane can effectively inhibit the swelling of the membrane and improve the alkali resistance and thermal stability of the membrane. However, the crosslinking will obstruct the ionic channel in the membrane and reduce the conductivity of the hydroxyl radical of the membrane. By selecting the large molecular crosslinker (BPPO), which has the same composition as the main chain of the graft anion exchange membrane, it can not only be used. The effective crosslinking can be achieved without destroying the phase separation morphology of the ionic membrane. The prepared membranes can improve the stability of the membrane and do not reduce the conductivity of the hydroxyl radicals. This study provides a new idea for the design of a reasonable crosslinking structure in the membrane system.
(5) 1- methyl imidazole (MIm) was used for the alkaline functionalization of brominated polyphenylene ether (BPPO), and imidazole anion exchange membrane was prepared. Because of the five membered heterocyclic structure and the existence of the conjugated structure of the imidazole ring, it could effectively prevent the hydrogen peroxide from attacking it. The alkali resistance and thermal stability of the imidazole anion exchange membrane are improved compared with the traditional quaternary ammonium anion exchange membrane. The output power of the imidazole film is 30mW/cm2.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TM911.4;TQ425.236

【共引文献】