Improvement of Oxidation Resistance of Crofer 22APU With Modified Surface for Solid Oxide Fuel Cell Interconnects

Abstract

One challenge for advancing solid oxide fuel cell (SOFC) technology is to develop interconnect materials with adequate conductivity and stability in oxidizing atmosphere for efficient long-term use. The objective of the present work is development of a two-step process which leads to the formation of internal barrier layer for Cr diffusion to the surface of current collector. ”Current collector with modified surface layer-LSM cathode” junctions were tested at 850ºC in air and current density 0,5A/cm2. Exposure time was up to 21000 hour. It was found that an irregularly shaped layer of thickness 2–5 mm was formed at a depth of 6–8 mm from the surface of current collector with modified near surface layer. Investigation of the composition showed that this irregularly shaped layer consists of a Cr2O3 phase and the thickness of such Cr2O3 islands increases as a function of operational time. The observed formation of such an internally oxidized Cr layer suppresses the formation of the insulating Cr2O3 phase on the current collector surface and improve electrical conductivity.