能源转换装置中膜电极集合体关键材料研究及性能的优化

发布时间：2018-03-12 12:22

  本文选题：甲醇　切入点：质子交换膜　出处：《吉林大学》2015年博士论文　论文类型：学位论文

【摘要】：当前,质子交换膜的甲醇透过率高和成本高及膜电极集合体的制备技术复杂是限制直接甲醇燃料电池性能提升的两个重要问题,也是阻碍直接甲醇燃料电池实现商业化的关键。为了克服现有质子交换膜的缺点,我们开发了新型质子交换膜,从磺化度、膜电极制备等方面提升了膜的实际工作性能。主要研究内容如下:1.探讨甲醇透过率和质子电导率对DMFC电池性能影响。通过调控聚合物单体比例合成了一系列具有不同磺化度的磺化聚芳醚酮砜(SPAEKS)膜,主要讨论了甲醇透过率和质子电导率对DMFC电池性能的直接影响。结果显示,磺化度提升与电导率的提升存在相关性,同时在高磺化度下亲水团簇的尺寸和数量的增加会提高单个磺酸集团的质子传导能力,该协同效应使得电导率迅速增加。同时,由于与质子共用传输通道,甲醇的透过性也会随磺化度提高迅速提升。因此,磺化度提升对电池性能具有正反两面的贡献:一方面能够提高材料离子电导率,从而降低电池的内阻;另一方面,甲醇的高透过率会导致燃料损失和严重的阴极混合电位问题,从而严重影响电池输出功率密度和能量效率。通过对不同膜在电池中的测试发现SPAEKS-0.6H为最适合的膜材料,以其为电解质的MEA放电性能可达50 m W cm-2,与Nafion膜材料相当。2.制备新型磺化聚醚醚酮膜及其MEA制备工艺的优化。从固体电解质水电解(SPE)技术的核心部件--膜电极集合体(MEA)入手,针对现有商用SPE水电解设备价格昂贵的缺点,将一种可能替代现有SPE膜的磺化聚醚醚酮聚合物制备成MEA。克服了制备中热压过程出现的问题,考察了催化剂与离聚物质量比、热压温度、热压时间三个影响因素对膜电极性能的影响。发现催化剂与离聚物质量比、热压温度、热压时间三个因素会对膜电极的性能造成明显的影响;根据极化曲线和计时电流的测试结果,催化剂与离聚物质量比、热压温度、热压时间三个因素过高和过低都不利于膜电极的性能表现;催化剂与离聚物质量比在5:1,热压温度在90℃到120℃之间,热压时间60 s左右是制备磺化聚醚醚酮膜电极较为合适的条件。3.采用原位沉积还原法制备超低铂载量的MEA。通过一系列物理化学表征表明采用原位沉积还原法制备的催化剂粒径大小均匀,采用Nafion聚合物所制备的催化剂粒径尺度全部分布在2nm-3nm间,而采用阴离子聚合物所制备的催化剂粒径尺度分布在0.6-1.6nm之间。利用原位沉积还原法所制备的MEA开路电压最高达0.83V,与常规热压法所制备的电池相比,在开路仅下降15%的情况下,催化剂载量降低了87.5%。为新型高热稳定性质子交换膜在电池中的进一步应用奠定基础。
[Abstract]:At present, the high methanol transmittance and high cost of proton exchange membrane and the complex preparation technology of membrane electrode collection are two important problems that limit the performance improvement of direct methanol fuel cell. In order to overcome the shortcomings of the existing proton exchange membrane, we have developed a new type of proton exchange membrane, from the degree of sulfonation, The main research contents are as follows: 1. The effects of methanol transmissivity and proton conductivity on the performance of DMFC batteries were investigated. A series of polymer monomers were synthesized by adjusting the ratio of polymer monomers. Sulfonated polyaryl ether ketone sulfone (SPAEKS) membrane with different degree of sulfonation, The direct effects of methanol transmittance and proton conductivity on the performance of DMFC cells are discussed. At the same time, increasing the size and number of hydrophilic clusters at high sulfonation degree can improve the proton conductivity of single sulfonic acid group, and this synergistic effect makes the conductivity increase rapidly. At the same time, because of sharing the transport channel with proton, The permeability of methanol also increases rapidly with the increase of sulfonation degree. Therefore, the enhancement of sulfonation degree has both positive and negative contributions to the performance of the battery: on the one hand, it can increase the ionic conductivity of the material, thereby reducing the internal resistance of the battery; on the other hand, The high transmission rate of methanol will lead to fuel loss and serious cathode mixing potential problems, which will seriously affect the output power density and energy efficiency of the battery. It is found that SPAEKS-0.6H is the most suitable membrane material through the measurement of different membranes in the cell. The discharge performance of MEA with MEA as electrolyte is up to 50 m W cm ~ (-2), which is equivalent to that of Nafion membrane material. The preparation of new sulfonated polyether ether ketone membrane and its preparation process of MEA are optimized. The core component of solid electrolyte water electrolysis is membrane electrode aggregation (MEA). A sulfonated polyether ether ketone polymer, which can replace the existing SPE membrane, was prepared by using a sulfonated polyether ether ketone polymer instead of the existing SPE membrane. The problem of hot pressing process was overcome and the mass ratio of catalyst to ionomer was investigated. It is found that the mass ratio of catalyst to ionomer, the temperature of hot pressing and the time of hot pressing have obvious influence on the performance of membrane electrode. According to the results of polarization curves and chronoamperometric measurements, the performance of the membrane electrode was affected by three factors: the mass ratio of catalyst to ionomer, the temperature of hot pressing and the time of hot pressing. The mass ratio of catalyst to ionomer is 5: 1, and the hot pressing temperature is between 90 鈩，

本文编号：1601542