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Application of Self-Humidifying Polymer Electrolyte Membranes for Fuel Cells

自增湿聚合物电解质膜在燃料电池中的应用

基本信息

批准号：
12555243
负责人：
WATANABE Masahiro
金额：
$ 4.16万
依托单位：
Yamanashi University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2001
项目状态：
已结题

项目摘要

Recently, we have proposed new self-humidifying polymer electrolyte membranes with highly dispersed nanometer-sized Pt and/or metal oxides for polymer electrolyte fuel cells (PEFCs) operated with dry H_2 and O_2. The Pt particles were expected to suppress the crossover by the catalytic recombination of H_2 and O_2, while the oxide particles (TiO_2) that have hygroscopic property were expected to adsorb the water produced at Pt particles together with that produced at the cathode reaction and to release the water once the PEM needs water. The PEFCs with these new PEMs demonstrated the superior performances and suppression of the crossover even under externally non-humidified condition, which are comparable to that of the conventional PEM fully humidified. In order to construct a practical PEFC stack, however, a mechanical strength of the PEM is an important property. Japan Gore-Tex developed a reinforced PEM with both a sufficient mechanical strength and high proton conductivity. It is desirable to prepare the self-humidifying PEM from a commercial reinforced PEM.In this research, we examined to develop a practical preparation protocol of such new PEMs and obtained the following results..1. The preparation protocol of TiO_2 nanoparticles in a commercial PEM via in-situ sol-gel reactions was developed, resulting in a transparent membrane with uniform distribution of TiO_2 among the membrane. A water adsorbability increased more than two times by dispersing only 2 wt % TiO_2 in the PEM.2. In order to get a uniform dispersion of Pt nanoparticles in the PEM, platinum-complex -cations were impregnated in the TiO2-PEM by an ion-exchanging reaction, followed by a reduction to Pt nanocrystals (0.1 mg/cm^2) with an aqueous solution containing excess neutral hydrazine. The Pt-dispersion process was optimized.3. The newly prepared Pt-TiO_2-PEM was confirmed to perform a self-humidifying operation in a PEFC with dry H_2 and O_2.

最近，我们提出了一种新型的自组装聚合物电解质膜，它具有高度分散的纳米Pt和/或金属氧化物，用于以干H_2和O_2为燃料的聚合物电解质燃料电池（PEFC）。Pt颗粒可以抑制H_2和O_2的催化复合，而具有吸湿性的氧化物颗粒（TiO_2）可以吸附Pt颗粒和阴极反应产生的水，并在PEM需要水时释放水。具有这些新型PEM的PEFC即使在外部非加湿条件下也表现出上级性能和对交叉的抑制，这与常规PEM完全加湿的性能相当。然而，为了构造实用的PEFC堆，PEM的机械强度是一个重要的性能。日本Gore-Tex开发了一种既具有足够的机械强度又具有高质子传导性的增强PEM。因此，我们希望从商业化的增强型PEM中制备自组装的PEM。在本研究中，我们研究了开发这种新型PEM的实用制备方案，并获得了以下结果。1.采用溶胶-凝胶法在工业质子交换膜中制备了纳米TiO_2粒子，得到了TiO_2粒子均匀分布的透明膜。仅在PEM中分散2wt%TiO_2，其吸水率就提高了2倍以上.为了使Pt纳米颗粒在PEM中均匀分散，通过离子交换反应将铂络合物阳离子浸渍在TiO 2-PEM中，然后用含有过量中性肼的水溶液还原为Pt纳米晶体（0.1 mg/cm^2）。优化了铂分散工艺.新制备的Pt-TiO_2-PEM在PEFC中以干H_2和O_2进行了自组装实验。