In-situ TEM Studies of Reduction and Reoxidation of Ni(O)-ceramic Composites

Quentin Jeangros (EPFL)
Project coordinators: Aïcha Hessler-Wyser (EPFL), Jan Van Herle (EPFL), Rafal Dunin-Borkowski (Jülich FZ)
Staff at DTU Cen: Thomas W. Hansen, Jakob B. Wagner
Funding: Swiss National Science Foundation
Solid oxide fuel cell (SOFC) technology is a promising energy conversion option at a time when durable solutions are sought due its high efficiency, flexibility of fuel use, delocalization of energy production, and reduction of pollutants such as NOx and SOx. The core of the project is to study and model by different techniques the performance degrading reduction and reoxidation reactions occurring in the nickel-ceramic anode during operation of the SOFC at around 800°C. TEM bright field micrographs acquired during a “redox” cycle of a NiO-YSZ composite in the environmental TEM: a) as-sintered NiO-YSZ anode prepared by focused ion beam, b) Ni-YSZ after reduction until 500°C under 1.4 mbar of H2, c) NiO-YSZ after reoxidation until 500°C under 3.2 mbar of O2.

Work at DTU CEN is centered on the use of the environmental transmission electron microscope (ETEM) and aims to understand in-situ the structural and chemical changes occurring during reduction and reoxidation (“redox“) cycles of the nickel-based composite at the nanoscale. The objective of the project is to suggest “redox” resistant structures, which will improve the lifetime of the cell without compromising the performances.

          

TEM bright field micrographs acquired during a “redox” cycle of a NiO-YSZ composite in the environmental TEM: a) as-sintered NiO-YSZ anode prepared by focused ion beam, b) Ni-YSZ after reduction until 500°C under 1.4 mbar of H2, c) NiO-YSZ after reoxidation until 500°C under 3.2 mbar of O2.