Exploring the origins of local transport resistance and characterizing the oxygen transport resistances in the catalyst layer (R_CL) are critical for cost reduction. In this paper, a comprehensive mesoscopic model for simulating coupled transport processes of oxygen and water vapor for different structural parameters under different operating conditions in reconstructed microstructures is proposed. The local transport resistance is calculated after achieving the limiting current density and the effective diffusivity of oxygen. The results demonstrate that R_CL increases greatly with decreasing platinum loading (L_Pt) and the transport resistances in other components of the cell dominate for high-loadings. Both the reduced oxygen permeation coefficient in the ionomer thin-film and the adsorption resistance account for the origins of local transport resistance. The local transport resistance increases with the bare carbon ratio for a constant L_Pt and Pt/C ratio due to the decreased effective ionomer surface, and increases with the I/C ratio due to the increased ionomer thickness and decreased Knudsen diffusivity. Due to the presence of liquid water, a slight decrease followed by an increase of the local transport resistance versus relative humidity is obtained. The contribution of ionomer thin-films to R_CL is more sensitive to liquid saturation compared with that of pores.

中文翻译：

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介观分析形态和操作条件对质子交换膜燃料电池催化剂层中输运阻力的影响

探索局部输送阻力的起源并表征催化剂层（R _CL）中的氧气输送阻力对于降低成本至关重要。本文提出了一种用于模拟氧气和水蒸气在不同工作条件下在不同工作条件下在重建的微结构中耦合传输过程的综合介观模型。在达到极限电流密度和氧气的有效扩散率之后，计算局部传输电阻。结果表明，R _CL随着铂含量的降低而大大增加（L _Pt）和电池其他组件的传输阻力在高负载情况下占主导地位。离聚物薄膜中降低的氧渗透系数和吸附阻力都是造成局部输送阻力的原因。由于有效离聚物表面的减少，对于恒定的L _Pt和Pt / C比，局部传输电阻随裸碳比的增加而增加，而由于离聚物厚度的增加和克努森扩散率的降低，其局部电阻随I / C比的增加而增加。由于液态水的存在，局部运输阻力相对于相对湿度略有下降，然后增加。离聚物薄膜对R _CL的贡献 与孔隙相比，它对液体饱和度更敏感。