To improve the performance of the Ce0.8Gd0.2O2−δ (GDC) electrolyte in a solid
oxide fuel
cell, it is necessary to block the electronic conduction due to Ce3+/Ce4+ transitions occurring at elevated temperatures.
In this work, a GDC/ScSZ double layer consisting of 50 nm GDC and
100 nm Zr0.8Sc0.2O2−δ (ScSZ) thin films were deposited on a dense GDC substrate by the
pulsed laser deposition (PLD) technology. The effectiveness of the
double barrier layer in blocking the electronic conduction of the
GDC electrolyte was investigated. The results showed that the ionic
conductivity of GDC/ScSZ–GDC was slightly lower than that of
GDC in the temperature range of 550–750 °C, but the difference
gradually decreased with the increase in temperature. At 750 °C,
the conductivity of GDC/ScSZ–GDC was 1.54 × 10–2 S·cm–1, which was almost the same as that
of GDC. The electronic conductivity of GDC/ScSZ–GDC was 1.28
× 10–4 S·cm–1, which
was lower than that of GDC. The conductivity results showed that the
ScSZ barrier layer can reduce electron transfer effectively. More
obviously, the open-circuit voltage and the peak power density of
the (NiO–GDC)|GDC/ScSZ–GDC|(LSCF–GDC) cell were
higher than those of the (NiO–GDC)|GDC|(LSCF–GDC) cell
in the temperature range of 550–750 °C. The superior performance
of the GDC/ScSZ–GDC electrolyte is attributed to the ScSZ thin
layer, which is effective in blocking the electronic conduction of
the GDC electrolyte.