Ceria interlayer-free Ba0.5Sr0.5Co0.8Fe0.2O3−δ–Sc0.1Zr0.9O1.95 composite cathode on zirconia based electrolyte for intermediate temperature solid oxide fuel cells

Abstract

We synthesized Ba0.5Sr0.5Co0.8Fe0.2O3−δ (BSCF) powders with a primary particle size of 20 nm using a Pechini type method. By using nanocrystalline BSCF powders, we were able to fabricate a ceria interlayer-free nanoporous cathode on a scandia stabilized zirconia (ScSZ) electrolyte at low temperatures. Cathodes sintered below 750 °C lacked sufficient mechanical adhesion to the electrolyte, while electrode was well adhered to the electrolyte when fired at 800 °C. The symmetrical BSCF-ScSZ|yttria stabilized zirconia (YSZ)|BSCF-ScSZ half-cell that we generated had an exceptionally low polarization resistance of 0.06 Ω·cm2 at 700 °C. The maximum power density of the BSCF-ScSZ|ScSZ|Ni-ScSZ unit cell was over 1 W cm−2 at 700 °C. We investigated the durability of the BSCF-ScSZ composite cathode by 30 thermo-cycles performed by varying the temperature from 200 to 700 °C. The polarization resistance after the test remained low at less than 0.08 Ω·cm2.