Impact of pore scale-modified GDL anisotropic properties on PEMFC performance

The performance of fuel cells is strongly influenced by the anisotropic transport properties of the gas diffusion layer (GDL), yet these characteristics are often simplified in macroscopic models. In this work, a three-dimensional proton exchange membrane fuel cell (PEMFC) model is developed. Anisotropic transport parameters are incorporated, which are derived from pore-scale simulations of reconstructed GDL microstructures. A parametric investigation is conducted on porosity, gas diffusivity, electrical conductivity, and thermal conductivity, considering conditions both before and after the application of graphite-filled PTFE coatings. Internal distributions of current density, temperature, and reactant and product species are analysed to clarify key transport mechanisms. Results show that cell performance is highly sensitive to through-plane gas diffusivity, while electrical conductivity exerts a secondary but notable influence. Reduced diffusivity leads to pronounced performance losses at high current densities, whereas increased electrical conductivity enhances cell output. Thermal conductivity has minimal impact on polarisation behaviour, though higher values enhance heat removal. Furthermore, decreased porosity following coating treatment causes additional performance losses, particularly in the concentration-polarisation region. These insights demonstrate how realistic, interrelated GDL properties influence overall cell behaviour and provide guidance for GDL optimisation. • A 3-D PEM fuel cell model with modified GDL properties has been developed. • Anisotropic transport properties calculated at pore-scale are integrated. • Sensitivity analyses on fuel cell performance with respect to various transport properties are performed. • The impact of porosity changes resulting from PTFE coating on fuel cell performance are considered.