The durability of PEMFCs is greatly influenced by the non-uniform degradation of catalyst particles across the thickness of cathode catalyst layer (CCL). Gradient CCL is one of the effective structures to improve both cell performance and durability. Here we employ mathematical modeling to evaluate several gradient CCL structures with Pt/C catalysts in terms of the evolution of electrochemical surface area (ECSA) and Pt mass during cycling. Results based on the two-layer models considering particle size gradient only show that larger Pt particles near the CCL/membrane interface can remarkably mitigate the loss of ECSA and Pt mass, but accelerate the Pt dissolution near the gas diffusion layer (GDL). An increase in the number of layers, corresponding to a more smooth decrease of particle size from the CCL/membrane interface to GDL, can effectively retain high ECSA after cycling. The CCL with an optimum performance is achieved by manipulating the particle size gradient and Pt loading gradient simultaneously, which gains more uniform distribution of Pt active surface for improving the end-of-test performance and durability. This work provides a strategy to achieve highly durable PEMFCs by combining the gradient of particle size and Pt loading in the CCL structure.

PEMFC的耐久性在很大程度上取决于阴极催化剂层（CCL）厚度上催化剂颗粒的不均匀降解。梯度CCL是改善电池性能和耐用性的有效结构之一。在这里，我们利用数学模型来评估在循环过程中电化学表面积（ECSA）和Pt质量的演变，用Pt / C催化剂评估了几种梯度CCL结构。基于考虑颗粒尺寸梯度的两层模型的结果仅显示，靠近CCL /膜界面的较大Pt颗粒可以显着减轻ECSA和Pt质量的损失，但会加速Pt在气体扩散层（GDL）附近的溶解。层数的增加，对应于从CCL /膜界面到GDL的粒径更平稳的减小，骑车后可以有效保持较高的ECSA。通过同时控制粒径梯度和Pt加载梯度来获得具有最佳性能的CCL，从而获得更均匀的Pt活性表面分布，从而改善测试的性能和耐久性。这项工作提供了一种通过结合CCL结构中的粒径梯度和Pt负载来实现高度耐用的PEMFC的策略。