【作者】 黄绵延；

【导师】 王宇新；

【作者基本信息】 天津大学 ， 化学工程， 2007， 博士

【摘要】 直接甲醇燃料电池(DMFC)的发展面临两大难题:一是阳极催化剂对甲醇反应的催化活性较低;二是通常使用的全氟磺酸质子交换膜的阻醇性能较差。因此开发出高性能的质子交换膜是DMFC研究的重要课题。本论文着眼于DMFC的现实需要和未来发展,在开发价格低廉的阻醇质子交换膜和耐高温质子交换膜方面进行了新的探索和尝试。聚醚醚酮(PEEK)和杂萘联苯聚醚酮(PPEK)是两种价格较低、性能优良的聚芳醚酮类聚合物。二者磺化后可用来制备DMFC质子交换膜。然而,纯磺化聚醚醚酮(SPEEK)、磺化杂萘联苯聚醚酮(SPPEK)膜的电导率与阻醇性能、尺寸稳定性之间存在难以协调的矛盾。高电导率要求聚合物的磺化度要高,但高磺化度会使膜的阻醇性能、尺寸稳定性变差。为解决这个矛盾,我们首次将具有较高电导率的质子导体1,2,4-三羧基丁烷-2-膦酸锆(Zr(PBTC))掺杂到较高磺化度的SPEEK及SPPEK中制备复合膜。实验表明,Zr(PBTC)与聚合物之间发生氢键作用,因此在不减小电导率的同时,复合膜的溶胀被有效地限制,膜的阻醇能力、尺寸稳定性得到提高。Zr(PBTC)/SPEEK复合膜的可使用温度也得到显著提高。使用温度的提高使得聚合物高电导率的特性得以发挥,因此Zr(PBTC)/SPEEK复合膜在高温时具有很高的电导率。我们还首次考察了掺杂Zr(PBTC)复合膜在高温不同湿度下的电导率及其高温气态进料DMFC性能。结果表明,Zr(PBTC)的掺杂能显著提高复合膜在低湿度时的电导率,因而复合膜的气态进料DMFC性能也得到提高。聚醚砜(PES)是一种成膜性能优良的工程热塑料。将PES混入高磺化度的SPEEK中能有效降低膜的溶胀、增强膜的阻醇能力、提高膜的使用温度。我们首次通过SEM实验得出SPEEK磺化度对共混膜微观形貌的影响。通过控制好SPEEK的磺化度及PES的混入量,可以制得电导率高、阻醇性能优良的PES/SPEEK共混膜。而且与具有相同离子交换容量的纯SPEEK膜相比,共混膜的阻醇性能及尺寸稳定性能更好。首次考察了上述复合膜及共混膜的直接甲酸、异丙醇、乙二醇及二甲醚燃料电池的单电池性能。更多还原

【Abstract】 The development and application of DMFC are restricted by two major technological barriers: one is low methanol oxidation activity for anode catalyst, and the other is methanol crossover from anode to cathode through membrane. Therefore, developing new proton exchange membrane has been very important. In this study, new proton exchange membrane materials with low cost are explored.Sulfonated poly (ether ether ketone) (SPEEK) and sulfonated poly (phthazinone ethet ketone) (SPPEK) membranes are promising alternative to Nafion membrane in DMFC for their high conductivity and better methanol resistance. However, in SPEEK and SPPEK membrane, there exits conflicts among ionic conductivity, methanol resistance and dimensional stability. Generally, high sulfonation degree (DS) offers the membrane with high conductivity, as well as the reduced methanol resistance and dimensional stability, thereby lowered applicable temperature.In order to overcome the conflicts, insolvable 1,2,4-tricarboxybutyl-2- phosphonate zirconium (Zr(PBTC)) with high conductivity and thermal stability was synthesized and incorporated into the SPEEK and SPPEK to fabricate novel composite membranes. Results show that the hydrogen bond happened between Zr(PBTC) and the polymers, which helps to reduce the swelling and methanol permeability of the composite membranes, and improve their dimensional stability without sacrificing conductivity. For the Zr(PBTC)/SPEEK composite membranes, high conductivity can be achieved as the applicable temperature is improved.High temperature DMFC is the new developing direction. For the hygroscopic property of Zr(PBTC), the conductivity of composite membranes under low relative humidity at high temperature(>100℃) was improved efficiently, and so did their vapor-feed DMFC performance at 120℃.In order to improve the properties of SPEEK membrane with high DS, poly(ether sulfone) (PES) was chosen and blended into SPEEK to fabricate PES/SPEEK blend membrane. Results show that the DS of SPEEK affects the microcosmic conformation of blend membrane. By controlling the DS of SPEEK and PES content, the blend membrane with high conductivity and excellent methanol resistance can be fabricated. Furthermore, compared with pristine SPEEK membrane with the same ion-exchange capacity, the blend membrane has better methanol resistance and dimensional stability. Single cell performance experiment indicates that the 30wt.%PES/SPEEK (DS=68.3%) membrane has the better performance than that of Nafion? 115 in DMFC.The performance of direct fuel cells with our novel membranes were tested, using formic acid, isopropanol, ethylene glycol and dimethy ether as fuels respectively.更多还原