Phase distribution visualization in Solid Oxide Fuel Cells by monochromatic neutron Bragg-edge tomography

Solid Oxide Cells (SOCs) efficiently convert chemical energy (e.g. hydrogen) into electrical energy in fuel cells (SOFC) or convert electrical energy into chemical energy in electrolysis cell (SOEC). Usually a SOC is constructed from three layers: a porous fuel electrode, a solid electrolyte and a porous air electrode. A major obstacle in the commercialization of SOC is their durability, which is mainly affected by the fuel electrode degradation [1, 2]. A prevalent material used for the electrodes is nickel-yttria stabilized zirconia (Ni-YSZ) cermet. During the initial operation the NiO particles are reduced into Ni. Throughout this process the microstructure of the fuel electrode and its support is established. The microstructure is responsible for the mechanical and electrochemical properties, which further determine the performance and durability of SOC. It has been demonstrated that there is a strong correlation between reduction / oxidation rates and the mechanical properties of the Ni-YSZ cermet [3]. This material, despite of the fact that it is a brittle ceramic, can experience large plastic deformations, when exposed to stress and reducing or oxidizing conditions at the same time.