Processing and performance of solid oxide fuel cell with Gd-doped ceria electrolyte

Fuel Cell performance was measured at 792–1095 K for Ni-GDC (Gd-doped ceria) anode-supported GDC film (60 μm thickness) with a (La0.8Sr0.2)(Co0.8Fe0.2)O3 cathode using H2 fuel containing 3 vol% H2O. A maximum power density, 436 mW/cm2, was obtained at 1095 K. The electrical conductivity of GDC electrolyte in N2 atmosphere of 10−15–100 Pa oxygen partial pressures (Po2) at 773–1073 K was independent of Po2, which indicated the diffusion of oxide ions. The conductivity of GDC in H2O/H2 atmosphere increased because of the further formation of electrons due to the dissociation of hydrogen in GDC (H2 → 2H+ + 2e−). The hole conductivity was observed at 873 K in Po2 = 100–104 Pa. The key factors in increasing power density are the increase of open circuit voltage and the suppression of H2 fuel dissolution in GDC electrolyte. These are controlled by the cathode material and Gd-dopant composition.