Effect of alumina on the curvature, Young's modulus, thermal expansion coefficient and residual stress of planar solid oxide fuel cells

Planar solid oxide fuel cells (SOFCs) are composites consisting of porous and dense functional layers as electrodes and electrolytes, respectively. Because of the thermo-elastic mismatch between the individual layers, residual stresses develop during manufacturing and cause unconstrained cells to warp. The addition of alumina decreases the thermal expansion coefficient (TEC) of the NiO and yttria-stabilized zirconia (YSZ) anode-support material. Correspondingly, the lower TECs have flattened the half cells during fabrication. In addition, the residual stress at room temperature (RT) for samples with more than 4 wt% alumina is only 20% of the residual stress of the samples without alumina, at approximately 100 MPa. The effects of Al2O3 on the curvature, Young's modulus, TEC and residual stress of the SOFC with (NiO–YSZ)1−x(Al2O3)x (x = 1–5 wt%) anode support are discussed in this work.

► The addition of alumina flattened the half cell before and after H2 reduction when it was fabricated under the same conditions as the half cell without alumina. ► When the alumina content was more than 2 wt% before reduction, the TECs of the samples were close to those of 8YSZ samples at 10.8 × 10−6 k−1. ► The residual stress for the sample with more than 4 wt% alumina was only 20% of the residual stress for the sample without alumina before reduction.