中文摘要：

分析了＂自呼吸式＂直接甲醇燃料电池膜电极性能衰减的因素及其影响程度。通过对膜电极进行2 000 h恒电流（25 m A/cm2）放电,对比了放电前后的极化曲线、交流阻抗谱及电化学活性面积。恒电流放电后,膜电极的最大功率密度从初始的29.1 m W/cm2下降到21.8 m W/cm2,开路电压基本不变;交流阻抗谱定量分析表明,阴极的电阻明显大于阳极,并且对膜电极性能衰减的影响程度是：阴极〉〉阳极〉质子交换膜;循环伏安测试显示阴极催化剂电化学活性面积的衰减为21%,明显大于阳极催化剂的衰减2%。

英文摘要：

The factors influencing the performance degradation of the air breathing direct methanol fuel cell（DMFC） were analyzed.And the contribution of each component was discussed.By keeping the membrane electrode assembly at a constant current density of 25 mA/cm2 for 2 000 h,the polarization curve,electrochemical impedance spectroscopy（EIS） and electrochemical surface area（ESA） were compared before and after stability test.The maximum power density decreased from 29.1 mW/cm2 to 21.8 mW/cm2,while the open circuit voltage did not show significant changes after testing.EIS studies show that the increase in the cathode resistance is much larger than that in the anode resistance.The contribution of each component on the performance degradation was determined as follows： cathode anode membrane.The cyclic voltammetry studies present that the ESA change in the cathode（21%） is much larger than that in the anode（2%）.