【作者】 张妮；

【导师】 刘惠玲；

【作者基本信息】 哈尔滨工业大学 ， 环境科学与工程， 2010， 博士

【摘要】 能源短缺和环境污染已成为制约人类经济发展和社会进步的两大全球性的难题。及早进行能源消费结构转型,实现能源的可持续发展,已得到国际社会的共识。燃料电池是一种新兴的绿色环保能源装置,在理论上只要不断的输入燃料和氧化剂,就能够源源不断的输出电流。质子交换膜燃料电池(PEMFC)具有高效节能、噪音低、寿命长等突出优点,因此成为全世界范围内研究的热点。质子交换膜(PEM)是PEMFC的核心部件,不但要分隔燃料与氧化剂以避免直接接触,而且还承担传导质子的功能。其性能将直接影响PEMFC的能量转化效率和使用寿命等。以Nafion膜为代表的商用PEM在使用过程中易造成环境污染,且废弃的Nafion膜难以处理,对环境具有潜在的危害;另外,Nafion膜还存在甲醇渗透系数高,高温质子传导率低等问题。为了使PEMFC真正成为绿色能源装置,同时提高和改善质子交换膜的综合性能,本文制备了一系列具有不同磺化度的环境友好磺化聚芳醚砜(SPAES)膜、双酚A型磺化聚砜(bi A-SPAES)膜、TiO2/SPAES和TiO2/bi A-SPAES复合膜以及PWA/bi A-SPAES复合膜,并对其结构进行了表征,对其性能进行了系统深入的研究,以期为Nafion膜寻找可替代的产品。通过亲核取代缩聚反应合成了一系列SPAES聚合物,通过粘度测试证明其具有较高的分子量,FTIR和1H NMR的测试结果表明得到了预期结构的聚合物,且该聚合物能铺成韧性较好的膜。通过检测发现SPAES膜具有较好的热稳定性和机械性能,且其磺化度对SPAES膜的性能有很大影响。随着磺化度的增加,SPAES膜的质子传导率增加,甲醇渗透系数同时也增加。本研究所制备的SPAES膜在磺化度为0.8时的质子传导率在80°C和100°C分别为0.116S/cm和0.126S/cm,优于Nafion 117膜(0.114S/cm和0.117S/cm),且其甲醇渗透系数仅为8.4×10-7 cm2/s,低于Nafion 117膜(2.1×10-6cm2/s)。通过亲核取代缩聚反应合成了一系列bi A-SPAES聚合物,通过粘度测试证明其具有较高的分子量,FTIR和1H NMR的测试结果表明得到了预期结构的聚合物,且该聚合物能铺成韧性较好的膜。通过检测发现bi A-SPAES膜具有较好的热稳定性和机械性能,且其磺化度对bi A-SPAES膜的性能有很大影响。随着磺化度的增加,bi A-SPAES膜的质子传导率增加,甲醇渗透系数同时也增加。本研究所制备的bi A-SPAES膜在磺化度为1.2时的质子传导率(0.10-0.15S/cm)在所有实验温度条件下均优于Nafion 117膜( 0.095-0.117S/cm),且其甲醇渗透系数为8.5×10-7cm2/s,低于Nafion 117膜。无机颗粒具有很好的亲水性,可以增加聚合物膜对水分子的约束力,增强水合作用,确保质子交换膜在高温条件下仍能保持一定的湿度,从而能够在高温时提高其质子传导的速率。为了克服磺化聚砜类膜低磺化度时质子传导率低、高磺化度时甲醇渗透系数高的缺点,进一步提高质子交换膜的综合性能,开发高性能的质子交换膜材料,本文采用共混的方法制备了性能优异的复合型质子交换膜。采用溶胶共混法制备了含有不同TiO2含量的TiO2/SPAES(Ds0.8, Ds1.0和Ds1.2)和TiO2/bi A-SPAES(Ds0.8, Ds1.0和Ds1.2)复合膜,通过FTIR和SEM测试结果表明TiO2已成功地掺入到SPAES和bi A-SPAES中。通过检测发现该系列复合膜具有较好的热稳定性和机械性能,且TiO2的含量对该系列复合膜的性能有很大影响。TiO2的掺入增加了该系列膜的质子传导率,同时改善了其阻醇性能。采用共混的方法制备了一系列具有不同磷钨酸(PWA)含量的PWA/bi A-SPAES(Ds0.4和Ds0.2)复合膜,通过FTIR和SEM测试结果表明PWA已成功地掺入到bi A-SPAES中。通过检测发现该系列复合膜具有较好的热稳定性和机械性能,且PWA的含量对该系列复合膜的性能有很大影响。PWA的掺入增加了该系列膜的质子传导率,同时增加了其甲醇渗透系数,但其甲醇渗透系数仍远远低于Nafion 117膜。综上所述,本研究所制备的SPAES和bi A-SPAES系列膜中,磺化度为0.8的SPAES膜与磺化度为1.2的bi A-SPAES膜综合性能较好,既改善了Nafion 117膜高温质子传导率低的问题,又改善了Nafion 117膜甲醇渗透系数高的问题;TiO2的掺入改善了高磺化度的SPAES和bi A-SPAES系列膜的阻醇性能和质子传导性;PWA的掺入改善了低磺化度的bi A-SPAES系列膜的质子传导性。因此,本研究所制备的膜有望成为直接甲醇燃料电池(DMFC)中质子交换膜材料的替代品,使燃料电池成为真正的绿色、高效的环保能源装置。更多还原

【Abstract】 Energy shortages and environmental pollution have been two global problems that restrict human society and economic development. All the world have made an agreement on energy sustainable development and changing the energy consumption structure as soon as possible. Fuel cell is an emerging green energy device. In theory, it can produce current as long as fuel and oxidant are added to it constantly. Proton exchange membrane fuel cell (PEMFC) which has many outstanding advantages, such as highly efficient energy-saving, low noise, long life, has been a world’s hot spot.Proton exchange membrane (PEM), the key part of PEMFC, not only separates the fuel from oxidant to avoid direct contact, but also transfers protons from anode to cathode. The properties of PEM would considerably impact on the PEMFC performances such as energy efficiency and service life.Nafion membrane, represented as a commercial PEM, is easy to cause environmental pollution in the course of using, and abandoned Nafion membrane is difficult to deal with and has a potential hazard to the environment; Besides, Nafion membrane has several problems, such as high methanol permeability, low proton conductivity at high temperature, etc. A series of environmental-friendly SPAES and bi A-SPAES membranes with different sulfonated degree (Ds), TiO2/SPAES and TiO2/bi A-SPAES composite membranes, and PWA/bi A-SPAES composite membranes were prepared in order to make PEMFC become a green energy device, and at the same time improve the overall performance of PEM. The structures of these membranes were characterized, and the properties of them were systematically studied, hoping to look for alternative material for Nafion membrane.A series of SPAES polymers were prepared by nucleophilic substitution reaction. The results of intrinsic viscosity showed that of their high molecular weight. The chemical structure of SPAES polymer was confirmed by FT-IR and 1H NMR spectra. All the polymers could be successfully cast into tough membranes. It was found that SPAES membranes had good thermal stability and mechanical properties by detecting, and Ds of SPAES had a great impact on the performance of membranes. The proton conductivities and methanol diffusion coefficient of SPAES membranes increased with the increase of Ds. The proton conductivity of SPAES membrane with Ds0.8 at 80°C and 100°C were 0.116S/cm and 0.126S/cm, respectively, which were higher than those of Nafion 117 membrane (0.114S/cm and 0.117S/cm); What’s more, the methanol diffusion coefficient of SPAES membrane with Ds0.8 was 8.4×10-7 cm2/s, which was lower than that of Nafion 117 membrane (2.1×10-6cm2/s).A series of bi A-SPAES polymers were prepared by nucleophilic substitution reaction. The results of intrinsic viscosity showed that of their high molecular weight. The chemical structure of bi A-SPAES polymer was confirmed by FT-IR and 1H NMR spectra. All the polymers could be successfully cast into tough membranes. It was displayed from detection that bi A-SPAES membranes had good thermal stability and mechanical properties, and Ds of bi A-SPAES had a great impact on the performance of membranes. The proton conductivities and methanol diffusion coefficient of bi A-SPAES membranes increased with the increase of Ds. The proton conductivity (0.10-0.15S/cm) of bi A-SPAES membrane with Ds1.2 was higher than that of Nafion 117 membrane (0.095-0.117S/cm) in all the experiments temperature conditions; and the methanol diffusion coefficient of bi A-SPAES membrane with Ds1.2 was 8.5×10-7cm2/s, which was lower than that of Nafion 117 membrane.Inorganic particles can increase sanction between water molecule and improve hydration because of their good hydrophilicity. They can ensure to keep adequate humidity in PEM at high tempereature, and therefore improve proton conductivity of the membranes at high temperature. We prepared composite PEM material with high performance by mixing inorganic particles in order to aviod the problems of low proton conductivity of the membranes with low Ds and high methanol diffusion coefficient of the membranes with high Ds, and improve the performance of PEM and exploit high-performance PEM.A series of TiO2/SPAES (Ds0.8, Ds1.0 and Ds1.2) and TiO2/bi A-SPAES (Ds0.8, Ds1.0 and Ds1.2) composite membranes with various contents of TiO2 particles were prepared through sol-gel reactions. FT-IR spectra and SEM images indicated the TiO2 particles were well dispersed within SPAES and bi A-SPAES polymer matrix. The results showed that TiO2/SPAES and TiO2/bi A-SPAES composite membranes had good thermal stability and mechanical properties by detecting, and the contents of TiO2 particles had a great impact on the performance of these composite membranes. The incorporation of TiO2 particles induced higher proton conductivity than the pure membranes and at the same time improved the property of methanol resistance. A series of PWA/bi A-SPAES (Ds0.4 and Ds0.2) composite membranes with various contents of PWA were prepared by blending method. FT-IR spectra and SEM images indicated the PWA particles were well dispersed within polymer matrix. PWA/bi A-SPAES composite membranes had good thermal stability and mechanical properties by detecting, and the contents of PWA particles had a great impact on the performance of these composite membranes. The introduction of PWA particles induced higher proton conductivity and methanol diffusion coefficient than the pure membranes, but the methanol diffusion coefficient was still much lower than that of Nafion 117 membrane.Summary, the comprehensive performance of SPAES membrane with Ds0.8 and bi A-SPAES membrane with Ds1.2 were better than others in this study. They not only improved the defect of low proton conductivity at high temperature, but also improved the defect of high methanol diffusion coefficient; The introduction of TiO2 particles improved the properties of methanol resistance and proton conductivity of SPAES and bi A-SPAES membranes with high Ds; The introduction of PWA particles improved the property of proton conductivity of bi A-SPAES membranes with low Ds. Therefore, the membranes prepared in this study were expected to be candidates for PEM of material in DMFC which make it a real green and effective energy device.更多还原