Performance and stability of proton conducting solid oxide fuel cells based on yttrium-doped barium cerate-zirconate thin-film electrolyte

The high performance anode supported single cells, comprising of BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3−δ)-BCZY (Ba0.98Ce0.6Zr0.2Y0.2O3−δ)//BCZY//NiO–BCZY have been fabricated by wet powder spraying and co-firing for depositing 10–15 μm thin film electrolytes on pre-sintered NiO–BCZY anode discs. The open circuit voltages of single cells were around 1.12–1.13 V at 600 °C indicating negligible gas leakage or mixed conduction through the electrolyte. The maximum power density of 493 mW cm−2 was obtained at 600 °C and 0.7 V under humid air as the oxidant gas and humid 75% H2 in N2 (2.76% H2O) as the fuel gas at a gas flow rate of 100 ml min−1. The area specific resistance of an anode supported button cell of BSCF–BCZY//BCZY//NiO–BCZY in fuel cell mode was about 0.46 Ω cm2 and in the electrolysis mode was 0.26 Ω cm2 at 600 °C, indicating high efficiency, reversible SOFCs. The single cell performance was stable for over 600 h at 600 °C. The stability of BCZY electrolyte in water-containing atmospheres was investigated by exposing sintered BCZY pellets to humid air (2.76% H2O) at 200 °C for 24 h or soaking them in boiling water for 3 h.

► Fabricated thin-film BCZY-based high performance anode supported SOFCs by wet powder spraying.
► Clarified nickel diffusion and its effect on the co-sintering of BCZY supported on Ni cermet anode.
► Demonstrated the highest power density in high temperature proton conducting planar cells.
► Demonstrated high performance reversible SOFCs comprising of thin-film BCZY and BSCF cathode.
► Investigated the chemical stability of BCZY in water-containing atmosphere for practical applications.