On effective transport coefficients in PEM fuel cell electrodes: Anisotropy of the porous transport layers

This paper reviews the approach taken in the literature to model the effective transport coefficients – mass diffusivity, electrical conductivity, thermal conductivity and hydraulic permeability – of carbon-fibre based porous electrode of polymer electrolyte membrane fuel cells (PEMFCs). It is concluded that current PEMFC model do not account for the inherent anisotropic microstructure of the fibrous electrodes. Simulations using a 2-D PEMFC cathode model show that neglecting the anisotropic nature and associated transport coefficients of the porous electrodes significantly influences both the nature and the magnitude of the model predictions. This emphasizes the need to appropriately characterize the relevant anisotropic properties of the fibrous electrode.