3D Visualisation of PEMFC Electrode Structures Using FIB Nanotomography

It is well known that the electrode structure of a PEMFC has a huge influence on the water management and thereby on the cell performance. In this work, two MEAs - one prepared by an airbrushing technique and the other by a novel fast spray coating technique (multilayered MEA) - were analysed with respect to porosity, pore size distribution, tortuosity and their electrochemical performance. FIB nanotomography with following 3D reconstruction, SEM investigation on ultramicrotomic thin-sections, and single cell tests were performed on these MEAs. The results show a higher porosity and lower pore size for the multilayered MEA. The multilayered MEA reaches a Pt utilisation of 1,962 mW mg(-1) and a peak power density of 210 mW cm(-2), whereas the air-brushed MEA only provides a Pt utilisation of 879 mW mg(-1) and a peak power density of 218 mW cm(-2). The Pt utilisation calculations showed in combination with the structural characterisations that a homogeneous pore structure and Pt distribution provide an advantage with regard to performance and efficiency of the PEMFC. Furthermore, the multilayered MEA may offer an advantage over the airbrushed MEA in its long term stability, which was observed in preliminary tests.