【作者】 赵亮；

【导师】 黄玉东；

【作者基本信息】 哈尔滨工业大学 ， 化学工程与技术， 2008， 博士

【摘要】 直接甲醇燃料电池（DMFC）具有高效率、高能量密度和环境友好等特点,在便携式电源领域中具有广阔的应用前景。质子交换膜（PEM）是DMFC的关键材料之一。DMFC中广泛使用的Nafion?膜具有良好的热稳定性、优异的化学稳定性和较高的电导率,但是其昂贵的成本和较差的阻醇性能阻碍了DMFC的进一步发展与应用。因此,低成本且高阻醇性的质子交换膜材料成为人们研究的热点。通过磺化反应制备了不同磺化程度（DS）的磺化杂萘联苯聚醚酮（SPPEK）,采用傅立叶红外光谱（FTIR）、核磁共振（NMR）和热重分析（TGA）对SPPEK进行了表征。考察了SPPEK膜的主要性能,结果表明SPPEK膜的吸水率、溶胀度、质子电导率和甲醇渗透性均随着DS的增大而逐渐增大,但甲醇渗透系数明显低于Nafion^?117膜。采用DS为0.85的SPPEK与磷钨酸（PWA）共混制备了SPPEK/PWA复合膜,PWA的引入在提高电导率的同时也增大了甲醇渗透性,但与Nafion^?117膜相比复合膜的仍具有较好的阻醇性能。DMFC测试表明,SPPEK/PWA复合膜的电池性能不如Nafion^?117膜,而且PWA的引入并没有改善复合膜的电池性能。通过缩合反应合成了2-（对氨基苯基）苯并（1,3）噁唑-5-胺（APBA）单体,利用L16（43）正交实验优化了合成工艺参数。通过FTIR、NMR和元素分析确定了单体的结构,高效液相色谱（HPLC）测试表明单体纯度达到98.20%。采用1,4,5,8-萘四酸二酐（NTDA）、2,2′-联苯二胺双磺酸（BDSA）和APBA为单体,通过高温一步聚合法合成了含有噁唑环的新型磺化聚酰亚胺（SPI-X）,通过调节二胺单体的比例控制磺化程度。研究了SPI-X膜的吸水率、溶胀度、热稳定性、质子电导率和甲醇渗透性能。结果表明,随着APBA含量的增加,SPI-X膜的电导率有所降低,但是阻醇性能得到改善,甲醇渗透性系数明显低于Nafion^?117膜。合成了4,4’-二（间胺基苯氧基）-3,3’-联苯双磺酸（mBAPBDS）单体,证实了单体具有预计的分子结构,单体纯度为92.15%。通过mBAPBDS、NTDA和四种不同结构的非磺化二胺单体共聚,合成了一系列新型磺化聚酰亚胺（SPIs）。TGA分析表明磺酸基团的分解温度在300℃以上,说明得到的SPIs具有出色的热稳定性。采用流延法制备了SPIs膜,离子交换容量（IEC）控制在1.87-2.49mmol/g之间,且与理论值基本一致,说明酰亚胺化比较完全。随IEC值的增加,SPIs膜的室温电导率逐渐增大,最高可达到8.65×10-3S/cm,接近于相同条件下Nafion^?117膜的电导率（9.80×10-3S/cm）。当IEC值在2.00mmol/g左右时,SPIs膜具有适当的吸水率和较好的尺寸稳定性,另外mBAPBDS的高碱性和柔顺的分子结构使得SPIs膜的水解稳定性和氧化稳定性也得到了明显的改善。甲醇渗透性测试表明,SPIs膜的甲醇渗透系数均明显低于Nafion^?117膜,且具有较高的选择性（Φ）,其中mBAPB系列和ODA系列膜的选择性约为Nafion^?117膜的3倍。采用选择性较高的Ic （4/1）和Id （4/1）膜制备膜电极,并组装成DMFC进行性能测试。结果表明,由Ic （4/1）和Id （4/1）膜组装的DMFC开路电压均高于Nafion^?117膜,电池性能虽然高于SPPEK/PWA复合膜,但与Nafion^?117膜相比还具有一定的差距,这是由于芳香族聚合物质子交换膜的膜电极制备工艺和测试条件没有进行优化的缘故。更多还原

【Abstract】 Direct methanol fuel cells （DMFCs） have attracted considerable attention as a portable energy system because of their high efficiency, high energy density, low emissions and environmental friendship. Proton exchange membrane （PEM） is one of the key components of DMFC system. Nafion? membranes are the state-of-the-art PEMs because of their good thermal stability and excellent chemical stability, as well as high proton conductivity. However, high cost and high methanol permeability of Nafion^?117 membrane have limited the development and application of DMFC. Therefore, many efforts have been done in the development of PEM materials with low cost and low methanol permeability.Sulfonated poly（phthalazinone ether ketone） （SPPEK） with various degrees of sulfonation （DS） were prepared and characterized by FTIR, NMR and TG analysis. It was found that the water uptake, swelling ratio, proton conductivity and methanol permeability of SPPEK membrane increased with DS level. In comparison with Nafion^?117 membrane, SPPEK membrane displayed good methanol-impeding property. SPPEK membrane with a DS level of 0.85 was chosen to prepare composite membrane with phosphotungstic （PWA）. The incorporation of PWA resulted in higher proton conductivity, while sacrificing methanol-impeding property, however, the methanol permeability coefficient （Pm） of SPPEK/PWA composite membrane was still lower than that of Nafion^?117 membrane. The DMFC performance of SPPEK/PWA composite membranes was not as good as Nafion^?117 membrane and was not improved due to the incorporation of PWA.The diamine monomer, 2-（4-aminophenyl）benzo（1,3）oxazol-5-amine （APBA）, was synthesized by condensation reaction. Various factors controlling the reaction were analyzed by L16 （43） orthogonal experiments. The structure of APBA was determined by FTIR, NMR and element analysis. The HPLC test indicated that the purity of the monomer reached 98.20%. A series of newl naphthalenic sulfonated polyimides （SPI-X） were synthesized using 1,4,5,8-naphthalenetetracarboxylic dianhydride （NTDA）, 2,2’-benzidinedisulfonic acid （BDSA） by one-step high temperature polymerization method. The sulfonated degree of SPI-X membranes was controlled through adjusting the molar ratio of BDSA to the non-sulfonated diamines. The water uptake, swelling ratio, proton conductivity and methanol permeability of SPI-X membranes were also investigated. The proton conductivity of SPI-X membranes decreased with APBA content, but methanol permeability of SPI-X membranes improved compared with Nafion^?117.The sulfonated diamines, 4,4’-bis（3-aminophenoxy）biphenyl-3,3’-disulfonic acid （mBAPBDS） was successfully synthesized and characterized. The mBAPBDS was used together with NTDA and common nonsulfonated diamines to prepare a series of sulfonated polyimides （SPIs）. TG analysis indicated that the SPI copolymers displayed good thermally stability with the decomposition temperature of above 300℃.The IEC value of SPI membranes prepared by solution casting method was 1.87-2.49mmol/g. The experimental results confirmed the assumption of complete imidization. Proton conductivity of SPIs membranes increased with DS level. The optimal proton conductivity of 8.65×10-3S/cm at room temperature was comparable to that （9.80×10-3S/cm） of Nafion^?117 membrane. It was also found that SPI membranes with IEC of 2.00mmol/g displayed adequate water uptake and good dimensional stability. The improved hydrolysis stability and oxidative stability of SPI membranes could be attributed to the high basicity of mBAPBDS and flexible main chain of polymer. Methanol permeability test showed that the SPIs membrane had much lower methanol permeability coefficient and thus much higher selectivity （Φ） value compared with Nafion^?117 membranes. TheΦvalues of SPIs membranes based on mBAPB and ODA increased to three times as compared with Nafion^?117 membranes.The Ic（4/1） and Id（4/1） membranes with high selectivity were used to prepare membrane electrode assembly （MEA）. The performance of MEA was then tested in a DMFC. The results showed the open circuit voltage （OCV） of DMFC equipped with Ic（4/1） and Id（4/1） membranes was higher than that of Nafion^?117 membrane, however, their maximal power density was not as good as Nafion^?117 membrane because of non-optimized preparation conditions of MEA based on aromatic polymer electrolyte membranes.更多还原