直接甲醇燃料电池膜电极稳定性的研究

Study on Performance Stability of Direct Methanol Fuel Cell

直接甲醇燃料电池(DMFC)运行过程中膜电极的稳定性是其商业化的关键问题之一。采用加热喷雾法制备膜电极并对其稳定性进行研究。结果表明,膜电极的电池性能经过连续极化后略有下降,但下降幅度不大,电压衰减速率仅1.0mV/h左右;经过25h恒电流放电,欧姆阻抗和传质阻抗都呈上升趋势,说明电池的欧姆极化损失加大、传质阻力上升。SEM测试结果表明,经过长时间恒电流放电后,膜电极催化层与电解质膜、扩散层及催化层等之间发生剥离,造成传质阻力上升和膜电极结构破坏,使电池性能衰退。循环伏安测试结果表明,经长时间放电运行后,阳极和阴极的氢脱附峰的积分面积减小,说明膜电极阴阳极催化层的电化学活性表面积降低。

The stability of membrane electrode assembly(MEA) is the one of key problems for commercial application of direct methanol fuel cell(DMFC).Stability of MEA prepared by heat-spraying method was studied.The results revealed that performance of the MEA declined at a rate of 1.0 mV/h after polarization for several times.This meant that the voltage of the cell was relatively stable.The ohm and mass transfer polarization increased after stability test.The scanning electron microscope(SEM) indicated that the combinations between the catalyst layer and membrane,diffusion layer and catalyst layer were destructed so that the polarization increased and the performance reduced.It could be concluded from the cyclic voltammetry results that the integral area of H-adsorption and desorption peaks of the anode and cathode decreased.That indicated that the electrochemical activity of surface area decreased.