In the ”Next Generation AutomotIve membrane electrode Assemblies (GAIA)“ project funded by the European Union, ZSW’s role is to investigate interactions between the individual components in a fuel cell and to carry out performance and lifetime tests on various fuel cell stacks provided by industry partners.
The first tests with fuel cells with different gas diffusion layers (GDL) revealed an unexpectedly strong dependence of cell performance characteristics at high current densities depending on the combination of the gas distribution field and the degree of graphitisation of the gas diffusion layer. The figure below shows a comparison of the performance characteristics of membrane electrode assemblies with a non-graphitised gas diffusion layer (GDL 1) and a graphitised gas diffusion layer (GDL 2) recorded in cells with different gas distribution arrays under humid operating conditions. In Hardware 1 and 2, there is a clear drop in the currentvoltage curve at high current densities, which indicates mass transport inhibitions due to interactions of the gas diffusion layers with the gas distribution fields. In Hardware 3, on the other hand, the current-voltage curve is at higher voltages. The described sensitivity can be attributed to difficulties in discharging liquid water, especially in Hardware 1. This finding is confirmed by comparing operation at a higher temperature and lower gas humidification.