Nicolas Hildenbrand

Ph.D. thesis

Summary

In the long road towards commercialization of Solid Oxide Fuel Cells, improving the cathode’s performance is a major milestone. Achieving low Area Specific Resistances at temperatures around 600 °C are required to meet the market demands in terms of costs and lifetime. In this thesis, different research projects focusing on the electrolyte / cathode assembly are described with as aims, an improvement of the performance and a better understanding of the cells. To decrease the Area Specific Resistance (ASR) of the cathodes, two solutions are explored and combined in this thesis. The first possibility is to replace the-state-of-the-art cathode materials by new and innovative materials. A study on Lanthanum Nickelate (La2NiO4+δ) as a porous electrode is shown This material shows excellent oxygen surface exchange and ionic diffusion. The second possibility is to use one of the state-of-the-art materials and improve its microstructure. By engineering the electrolyte / cathode interface, it is shown for La0.6Sr0.4Co0.2Fe0.8O3-δ and for La2NiO4+δ that the oxygen surface transport on the cathode grains can be enhanced. The trick consists of introducing a thin dense layer of the cathode material between the porous electrode and the electrolyte. Finally,a new method to produce a complete cell with Pulsed Laser Deposition is presented. PLD is a typical example of what nanotechnology can bring to improve Solid Oxide Fuel Cells.