Characterization of electrolyte layers of plasma-sprayed metal supported solid oxide fuel cells

•The reduction of nickel oxide limits the performance of SOFC.•The transformation to nickel induces tensile stresses of 300 MPa.•Plasma-spraying of nanostructured powders does not originate nanostructured layer.•A nano-amorphous silica and molybdenum layer was found between cathode/electrolyte.•The electrolyte presents no global texture but local crystalline fiber texture.

To increase the performance and durability of metal-supported solid oxide fuel cells it is important to understand the stresses occurring during manufacturing and operation of cells. In this work, the electrolyte layers of plasma-sprayed metal supported solid oxide fuel cells were analyzed by means of scanning electron microscopy, electron backscatter diffraction, X-ray diffraction and transmission electron microscopy in different stages of their fabrication (as powder, as sprayed material and as a reduced layer in the fuel cell system). It has been found that the determinant process for the gas permeability and performance of the cell is the reduction of the anode. During this process a tensile stress of 300 MPa is induced in the electrolyte material, generating crack networks with undesired gas permeation in the cell. Furthermore, the reduction reaction, from nickel oxide to pure nickel, produces 40% volume shrinkage. Texture and chemical homogeneity analyses of nano-powder material for functional layers are also presented. Finally, anode optimization strategies for metal supported solid oxide cells are discussed.