Development of solid oxide cells by co-sintering of GDC diffusion barriers with LSCF air electrode

The effects of a Cu-based additive and nano-Gd-doped ceria (GDC) sol on the sintering temperature for the construction of solid oxide cells (SOCs) were investigated. A GDC buffer layer with 0.25-2 mol% CuO as a sintering aid was prepared by reacting GDC powder and a CuN2O6 solution, followed by heating at 600 degrees C. The sintering of the CuO-added GDC powder was optimized by investigating linear shrinkage, microstructure, grain size, ionic conductivity, and activation energy at temperatures ranging from 1000 to 1400 degrees C. The sintering temperature of the CuO GDC buffer layer was decreased from 1400 degrees C to 1100 degrees C by adding the CuO sintering aid at levels exceeding 0.25 mol%. The ionic conductivity of the CuO GDC electrolyte was maximized at 0.5 mol % CuO. However, the addition of CuO did not significantly affect the activation energy of the GDC buffer layer. Buffer layers with CuO-added GDC or nano-GDC sol-infiltrated GDC were fabricated and tested in co-sintering (1050 degrees C, air) with La0.6Sr0.4C0.2Fe0.8O3-delta (LSCF). In addition, SOC tests were performed using button cells (active area: 1 cm(2)) and five-cell (active area: 30 cm(2)/cell) stacks. The button cell exhibited the maximum power density of 0.89 W cm(-2) in solid oxide fuel cell (SOFC) mode. The stack demonstrated more than 1000 h of operation stability in solid oxide electrolysis cell (SOEC) mode (decay rate: 0.004%/kh).