磺化聚醚醚酮及其纳米复合质子交换膜的制备与性能研究

发布时间：2018-11-10 16:57

【摘要】：直接甲醇燃料电池(DMFC)是一种直接以甲醇作燃料的新型质子交换膜燃料电池(PEMFC),具有能量效率高、清洁无污染等优点,是现今最有前景的清洁能源之一。质子交换膜(PEM)是DMFC的核心组成部件之一,担负着传导质子并分隔阴阳极的双重作用,对燃料电池的运行状况起着决定性的作用。但是现在广泛使用的全氟磺酸膜不仅价格昂贵,还存在着严重的甲醇渗透问题,大大降低了燃料电池的性能。因此,需要开发价格低廉、燃料透过率低的无氟磺化高分子材料。磺酸化聚醚醚酮(SPEEK)具有相对高的导质子性、良好的热稳定性和力学性能,且廉价易得,是一种很好的质子交换膜材料。本文成功制备了一系列以乙醇/水混合溶液为溶剂的SPEEK质子交换膜。与以DMAc为溶剂的质子交换膜相比,质子电导率得到提高。成膜温度对膜的性能有很大的影响。较低的成膜温度有利于亲水相聚集,促进相分离。同时,促进膜表面磺酸基团的聚集排布,从而膜具有更高的质子。首先利用聚多巴胺和十二烷基苯磺酸钠(SDBS)在石墨相碳化氮(Graphitic Carbon Nitride,g-C_3N_4)的吸附作用,制备了两种改性g-C_3N_4。将其与SPEEK掺杂制备了SPEEK/改性g-C_3N_4复合质子交换膜。聚多巴胺和SDBS上的亲水基团使g-C_3N_4纳米片与SPEEK基体的界面相容性提高,复合膜中离子簇相密度增加,亲水区连接性更好,膜中质子流动性增强。掺杂改性g-C_3N_4的复合膜的质子电导率得到提高。g-C_3N_4纳米片与SPEEK相互作用,使聚合物链的流动性被抑制,甲醇渗透率降低。通过将SDBS和g-C_3N_4均匀分散的混合液直接与SPEEK铸膜液共混制备了SPEEK/g-C_3N_4/SDBS复合质子交换膜。g-C_3N_4分散均匀,与SPEEK聚合物基质的界面相容性大大改善。SPEEK基体中形成连续的亲水通道,离子簇密度增加,膜中质子流动性增强。此外,SDBS表面的磺酸根与SPEEK聚合物相互作用,形成连续的离子簇,增加了导电通路。制备的SPEEK/g-C_3N_4/SDBS复合质子交换膜的质子电导率有很大提高,添加2 wt%填料时,导电性比纯SPEEK膜提高了60%。
[Abstract]:Direct methanol fuel cell (DMFC) is a new type of proton exchange membrane fuel cell (PEMFC),) with direct methanol as fuel. It has the advantages of high energy efficiency, clean and pollution-free, and is one of the most promising clean energy sources. Proton exchange membrane (PEM) is one of the core components of DMFC, which plays a dual role in conducting protons and separating anode and cathode, and plays a decisive role in the operation of fuel cells. However, the perfluorinated sulfonic acid membrane, which is widely used now, is not only expensive, but also has serious methanol permeation problem, which greatly reduces the performance of fuel cells. Therefore, it is necessary to develop fluorine-free sulfonated polymer materials with low price and low fuel transmittance. Sulfonated polyether ether ketone (SPEEK) is a kind of proton exchange membrane material with relatively high proton conductivity, good thermal stability and mechanical properties. In this paper, a series of SPEEK proton exchange membranes using ethanol / water mixed solution as solvent have been successfully prepared. Compared with the proton exchange membrane using DMAc as solvent, the proton conductivity was improved. The temperature of film formation has a great influence on the performance of the film. Lower film forming temperature is favorable to hydrophilic gathering and promoting phase separation. At the same time, it promotes the aggregation and arrangement of sulfonic groups on the membrane surface, so that the membrane has higher protons. Firstly, two kinds of modified g-C _ 3N _ 4 were prepared by the adsorption of poly (dopamine) and sodium dodecylbenzene sulfonate (SDBS) on graphite-phase carbonized nitrogen (Graphitic Carbon Nitride,g-C_3N_4). SPEEK/ modified g-C_3N_4 composite proton exchange membrane was prepared by doping it with SPEEK. The interfacial compatibility between g-C_3N_4 nanoparticles and SPEEK matrix was improved by the hydrophilic groups on polydopamine and SDBS. The ionic cluster phase density and hydrophilic zone connectivity of the composite membranes were increased, and the proton fluidity in the membranes was enhanced. The proton conductivity of the composite membrane doped with modified g-C_3N_4 was improved. The interaction between g-C_3N_4 nanoparticles and SPEEK inhibited the flowability of polymer chain and decreased the methanol permeability. The SPEEK/g-C_3N_4/SDBS composite proton exchange membrane was prepared by blending the uniformly dispersed mixture of SDBS and g-C_3N_4 with the casting solution of SPEEK directly. The g-C_3N_4 was uniformly dispersed. The interfacial compatibility with SPEEK polymer matrix was greatly improved. A continuous hydrophilic channel was formed in the SPEEK matrix, the ion cluster density increased and the proton fluidity in the membrane increased. In addition, the sulfonic radical on the surface of SDBS interacts with the SPEEK polymer to form a continuous ion cluster, which increases the conduction pathway. The proton conductivity of the SPEEK/g-C_3N_4/SDBS composite proton exchange membrane was greatly improved. The conductivity of the SPEEK/g-C_3N_4/SDBS composite proton exchange membrane was increased by 60% than that of the pure SPEEK membrane when 2 wt% filler was added.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM911.4;TQ425.23

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