Abstract:

To study the effect of operating voltage on the degradation of membrane electrodes of proton exchange membrane fuel cell (PEMFC) under long-term stable operation conditions, a coupled multi-physics field PEMFC model including carbon corrosion, Pt oxidation, dissolution and ionomer degradation is established for numerical simulation. The results show that with the increase of operating voltage, the rate of Pt dissolution and carbon corrosion in cathode catalyst layer (CCL) is accelerated, the oxidized area on the Pt surface increases dramatically after 500 hours, the radius of the agglomerates in CCL and the concentration of Sulfonic acid group in the proton exchange membrane decrease drastically, and the recession area is mainly concentrated in the cathode inlet and the degree of the recession is increased drastically at a high voltage. When the cell is operated at 0.8 V for 500 hours, the thickness of CCL and membrane at the cathode inlet decreased significantly by 13.62% and 35.30%, respectively. The electrochemcial active surface area of CCL and the ionic conductivity of the membrane decreased by 59.9% and 6.9%, respectively, and the equivalent weight of the membrane increased by 7.4%, and the above indexes declined drastically in the first 100 hours, and then gradually stabilized. The conclusion can provide a guideline for the optimization of membrane electrode material design and control strategy.

Key words: PEMFC, membrane electrode, operating voltage, CFD, degradation, simulation

摘要：

为研究长期稳定运行条件下，工作电压对质子交换膜燃料电池膜电极衰退状况的影响，建立了包含碳腐蚀、Pt氧化与溶解以及离聚物降解的PEMFC多物理场耦合模型进行数值模拟。研究结果表明：随着工作电压增加，阴极催化层中Pt溶解与碳腐蚀速率加快，500小时后Pt表面氧化的区域大幅增加，阴极催化层中团聚体半径与质子交换膜中磺酸基团浓度剧烈减小，衰退区域主要集中在阴极入口处且高电压下衰退程度急剧增加。电池在0.8 V下运行500小时后，阴极入口处阴极催化层与膜厚度显著减小，分别降低13.62%与35.30%；阴极催化层电化学活性面积和膜的离子电导率分别减小59.9%与6.9%，膜的当量质量增加7.4%，且上述指标前100小时内衰退剧烈，随后逐渐趋于平缓。结论可为膜电极材料设计与控制策略的优化提供参考。

关键词: 质子交换膜燃料电池, 膜电极, 工作电压, 计算流体力学, 衰退, 模拟