质子交换膜燃料电池的阳极分析与优化

Anode analysis and optimization of proton exchange membrane fuel cells

以聚集体模型描述催化层结构,自由堆积球模型计算催化层的有效质子和电子传导率,建立了质子交换膜燃料电池(PEMFC)的二维稳态数学模型,目的是研究阳极结构和工作条件的优化。模型方程涉及气体传输、质子和电子传导以及电化学反应等过程。一致的实验数据和模拟结果验证了模型的有效性。计算结果表明,阳极气体中的水含量在一定范围内会通过膜电导率影响燃料电池性能;阳极扩散层厚度和孔率等对燃料电池无明显作用;阳极催化层中过低或过高的电解质含量会恶化PEMFC的极化行为;阳极催化层的催化剂载量还有进一步降低的潜力。

A two-dimensional, steady-state model was presented for the analysis and optimization of the anode in proton exchange membrane fuel cells by taking into account the electrochemical kinetics of oxygen reduction and hydrogen oxidation, electron and proton transfer, and gas transport. The catalyst layers were assumed to be composed of spherical agglomerates and the effective electronic and protonic conductivity were educed from the ideal random-packed-sphere model. The model was validated by the good agreement between the simulation and experiment. The results revealed that the PEMFC performance was substantially dependent on the anode water content. Thickness and porosity of the anode gas diffusion layer play no obvious roles in PEMFC performance. Performance decline was demonstrated when the volume fraction of the electrolyte at anode catalyst layer was too low or too high. It was also implied that the catalyst Ioadings in anode could be further reduced.