Abstract:

Gas diffusion layer is a key component of a proton exchange membrane fuel cell. It can support and protect the proton exchange membrane and catalyst layer, and provide the channels for electrons conduction and gas transfer. As the main parameter of the diffusion layer, the porosity affects the characteristics of the diffusion layer and ultimately affects the battery performance. In this paper, a 3D agglomerate model is established to study the influence of constant value and stepwise non-uniform distribution on cell performance, and also explore the optimal porosity at different voltages. The results show that increasing porosity can improve cell performance in concentration polarization region, but reduce the performance in ohmic region. Porosity increasing along flow direction is beneficial for cell performance, but the change magnitude should be smaller. Porosity increasing from under rib to under gas channel can enhance cell performance. The optimal porosity is various at different voltages and reduces with voltage increasing, and the current density can be increases by 5.28% at 0.2 V.

Key words: hydrogen energy, proton exchange membrane fuel cell, gas diffusion layer, porosity, numerical simulation

摘要：

气体扩散层是质子交换膜燃料电池的关键部件，在电池内用于支撑和保护质子交换膜和催化剂层，并且为电子传导和气体输运提供通道。孔隙率作为扩散层主要参数，其大小影响扩散层特性，最终影响电池性能。所以，为获得较有利的孔隙率，本文建立三维全电池结块模型，计算定值及沿不同方向阶梯型变化孔隙率对电池性能的影响，并且计算不同电压下对应的最佳孔隙率值。结果表明，增大孔隙率可明显提升浓差极化区电池性能，但是会降低欧姆极化区性能。沿流动方向孔隙率增加可改善电池性能，但是孔隙率变化幅度不宜过大，从脊下到流道下孔隙增加可提升电池性能。不同电压下使得电流密度最大时对应的孔隙率不同，且随电压增加而降低，0.2 V时电流密度可提升5.28%。

关键词: 氢能, 质子交换膜燃料电池, 气体扩散层, 孔隙率, 数值模拟