The gas diffusion layer (GDL) is considered one of the most significant components in the proton exchange membrane fuel cell (PEMFC). Its electrical impedance is crucial to the performance of power generation for PEMFC. The study of the conduction mechanism of the GDL substrate-carbon fiber paper(CFP) treated with PTFE is still a considerable challenge. This work reveals that the type and number of contact points are direct factors that affect CFP through-plane resistance. The CFP resistance along the through-plane direction is a function of the contact point density inside CFP, rather than traditional loading pressure. Based on the structural characteristics of CFP, a graph theory model that can express the complex three-dimensional structure and anisotropy of CFP is constructed instead of the finite element model or formula model—using the characterization of the distribution of PTFE in the CFP section. The accuracy of model prediction for the CFP resistance of 0 wt% and 20 wt% PTFE can reach 95% and 90%, respectively. This study provides a fundamental basis for the design and processing of CFP with lower electrical loss and is of great significance for further improving the power generation efficiency of PEMFC.

气体扩散层（GDL）被认为是质子交换膜燃料电池（PEMFC）中最重要的成分之一。它的电阻抗对于PEMFC的发电性能至关重要。研究用PTFE处理的GDL基材-碳纤维纸（CFP）的导电机理仍然是一个巨大的挑战。这项工作表明，接触点的类型和数量是影响CFP贯穿平面电阻的直接因素。沿平面方向的CFP电阻是CFP内部接触点密度的函数，而不是传统的加载压力。根据CFP的结构特点，利用CFP截面中PTFE的分布特征，构建了可以表达CFP复杂的三维结构和各向异性的图论模型，而不是有限元模型或公式模型。对于0 wt％PTFE和20 wt％PTFE的CFP阻力，模型预测的准确性分别可以达到95％和90％。该研究为电损耗较低的CFP的设计和加工提供了基础，对进一步提高PEMFC的发电效率具有重要意义。