Abstract: Polypyrrole modified Nafion membranes（PPy/Nafion）are prepared by FeCl3 oxidation methods. In addition，Co is chemically reduced on the cathode side of the modified membrane to prepare Co-PPy/Nafion membrane. The thermal stability，methanol penetrability and proton conductivity of Nafion membranes and the modified membranes are studied by TG，CV and AC impedance. Results show that PPy/Nafion and Co-PPy/Nafion have better thermal stability and low methanol permeation than Nafion membrance. Membrane-electrode-assemblies（MEAs）for a DMFC are fabricated by using Nafion membranes，PPy/Nafion and Co-PPy/Nafion respectively，with PtRu/C as an anode catalyst and Pt/C as a cathode catalyst. It is found that the modification of Nafion membrane with Co-polypyrrole can improve the performance of MEA to a great extent when the cell is operated at higher methanol concentrations and higher discharging current densities.

Key words: Nafion membrane, polypyrrole, methanol permeability, proton conductivity

摘要： 用FeCl₃化学氧化法制备了PPy/Nafion改性膜，采用浸渍-还原法在PPy/Nafion阴极侧上沉积Co金属，制得Co-PPy/Nafion电解质膜。采用TG、CV及交流阻抗谱测试了Nafion膜及改性膜的热稳定性，质子电导性和甲醇渗透性能，结果表明：PPy/Nafion及Co-PPy/Nafion改性膜具有更好的热稳定性和抗甲醇渗透性。分别以Co-PPy/Nafion改性膜、PPy/Nafion改性膜和纯Nafion膜为电解质膜，PtRu/C为阳极催化剂，Pt/C为阴极催化剂组装DMFC并考察其性能。实验结果表明：Co-PPy/Nafion改性膜组装单电池在高浓度甲醇及大电流密度的测试条件下，表现出更优异的电池性能。

关键词: Nafion膜, 聚吡咯, 甲醇渗透, 质子电导率