Electrical and mechanical characterization of the gas diffusion layer during compression in PEM fuel cells

Abstract

In this paper, the electrical and mechanical behavior of the gas diffusion layer (GDL) is characterized under compressive deformation in the proton exchange membrane (PEM) fuel cell by developing an efficient analytical model. For the first time, in the electrical part of this model, the equivalent resistance circuit of the GDL is constructed by considering the resistance of the contacts between fibers. The variation of the contact resistance with normal stress is determined and applied to the resistance circuit model to calculate the variation of the GDL bulk electrical resistance during its compressive deformation. In the mechanical part, the deformation of carbon fibers in the GDL microstructure is captured by Timoshenko beam theory to determine the compressive stress-strain curve of the GDL. In both mechanical and electrical parts, the number of contacts between fibers is updated under compression by introducing an innovative procedure. The mechanical part of the model has been also implemented in the Abaqus/Explicit software by adopting Timoshenko beam elements for meshing the fibers. The obtained stress-strain and electrical resistance-stress curves of different GDLs have been compared with experimental data to verify the model. This model can be effectively used to improve the design and performance of PEM fuel cells.