直接甲醇燃料电池活化过程中膜电极变化

Alteration of the Membrane Electrode Assemblies during Direct Methanol Fuel Cell Activation Process

采用水煮电极和恒压放电两种方法活化膜电极(MEA),考察了活化前后膜电极及电极上阳极(PtRu/C)与阴极(Pt/C)催化剂的变化情况。电极极化曲线、电化学阻抗谱(EIS)测试发现,活化后的电极性能有较大提高,膜电极的电阻降低。X射线衍射(XRD)的分析表明膜电极上阳极和阴极催化剂都发生聚集长大。分别采用CO吸附溶出法和氢吸脱附法测量MEA的阳极和阴极催化剂的电化学活性面积(ESA),结果表明,尽管催化剂的颗粒长大,但经过恒压放电活化的阳极和阴极的电化学活性面积分别提高了20.9%和5.0%。同时发现恒压放电活化的方法相对于水煮电极活化的方法更有利于提高膜电极性能。

This research is aimed to investigate the alteration of the membrane electrode assemblies （MEAs） and the anode catalysts （PtRu/C） as well as cathode catalysts （Pt/C） during the activation process in DMFCs by using water-boiling activation method and the constant voltage discharge activation method. The polarization curves show that the performances of the activated MEAs are greatly increased. The electrochemical impedance spectra （EIS） reveal that the resistances of the activated MEAs are decreased. Scanning electron microscopy （SEM） images and X-ray diffraction （XRD） patterns show that the particle sizes of catalysts increase in both the anode and cathode. Electrochemical surface areas （ESAs） of anode and cathode catalysts were evaluated by CO-stripping and hydrogen-desorption test, respectively. It was found that the ESAs of the anode and cathode catalysts increase by 20.9% and 5.0%, respectively, although the particle sizes of the catalysts increase. It is proved that the constant voltage discharge activation method is more beneficial to activating the performance of MEAs compared to the water-boiling activation method.