高温质子交换膜燃料电池催化层孔尺度模拟

为了研究磷酸在高温质子交换膜燃料电池催化层中再分布对电极性能的影响，使用聚焦离子束电子扫描显微镜对自制的扩散电极成像，重构得到了三维的催化层几何模型；采用多弛豫时间格子玻尔兹曼模型对磷酸在催化层的迁移行为进行仿真，模拟得到递减型和准均匀型2种不同的磷酸分布形式；采用孔尺度模型求解不同条件下的电极传输性质。结果表明在磷酸含量较低时，准均匀型的磷酸分布具有稍优的电化学活性表面积和稍差的氧气和水蒸气有效扩散系数；在磷酸含量较高时，2种分布的电化学活性表面积相似，但是准均匀型分布具有更好的氧气和水蒸气有效扩散系数。

Pore-scale modelling of reconstructed catalyst layer for high-temperature proton-exchange membrane fuel cell

To investigate the effect of redistribution of phosphoric acid in the catalytic layer of high-temperature proton-exchange membrane fuel cells on the electrode performance, focused ion beam-scanning electron microscopy was employed to image the in-house gas diffusion electrode, and a three-dimensional model of the catalytic layer was reconstructed. By using multiple relaxation-time-lattice Boltzmann model to simulate the migration and redistribution of phosphoric acid in the catalytic layer, two different phosphoric acid distribution forms (decreasing type and quasi-uniform type) were obtained. Pore-scale modelling was used to examine the electrode transmission properties under different conditions. The results show that when the phosphoric acid content is low, the quasi-uniform phosphoric acid distribution has slightly larger electrochemical active surface area and slightly lower effective diffusion coefficients of oxygen and water vapor. When the content of phosphoric acid is high, the electrochemical active surface areas of the two distribution types are similar, but the quasi-uniform distribution has higher effective diffusion coefficients of oxygen and water vapor.