用非均匀团聚体模型模拟燃料电池老化过程

Simulation of fuel cell aging process with heterogeneous agglomerate model

在燃料电池老化过程中,催化层中催化剂的迁移和粒径增加会造成燃料电池的性能下降。本文提出了一种新型的团聚体分层分布模型,且分层界面可沿膜厚方向发生线性变化。通过宏观电极模型和团聚体亚尺度模型的耦合,用有限元法分析了团聚体不均匀分布对质子交换膜燃料电池性能的影响。研究表明,靠近团聚体外侧的催化剂的流失对电池性能影响很大,当没有催化剂的外侧区域达到0.1倍半径时,输出电压为0.2V时的电流密度下降89.8%;当没有催化剂的内侧区域达到0.1倍半径时,输出电压为0.2V时的电流密度下降25%左右。相比于向质子交换膜方向的催化剂迁移,向气体扩散层方向的催化剂迁移对电池性能影响更大,其中分层递增分布的团聚体模型的电池电流密度是均匀分布团聚体模型的60%左右,分层递减分布模型的电流密度是均匀分布团聚体模型的10%左右。此外,铂负载量增加一倍对递增分布模型的电池性能有所提高。

During the aging process of fuel cell, the migration of catalyst in the catalytic layer and the increase of the particle size will deteriorate the performance of fuel cell. This paper proposed a new agglomerate layered distribution model, in which the layered interface can change linearly along the thickness of the film. Through the coupling of the macro-electrode model and the aggregate sub-scale model, the influence of the uneven distribution of aggregates on the performance of the proton exchange membrane fuel cell was analyzed by the finite element method. The results showed that the loss of catalyst near the outside of the aggregate had great influence on the battery performance. When the outer region without catalyst reached 10% of the radius, the current density decreased by 89.8% when the output voltage was 0.2V. When the inner region without catalyst reached 10% of the radius, the current density at the output voltage of 0.2V decreased by about 25%. Compared with the catalyst migration toward the proton exchange membrane, the catalyst migration toward the gas diffusion layer had greater impact on fuel cell performance. The fuel cell current densities from the layered and incrementally distributed agglomerate model and the layered decreasing distributions model were about 60% and 10% of those given by the uniformly distributed agglomerate model respectively. In addition, the performance of the cell could be improved by doubling the platinum loading.