High performance metal-supported solid oxide fuel cells fabricated by thermal spray

Abstract

Metal-supported solid oxide fuel cells (SOFCs) have been fabricated and characterized in this work. The cells consist of porous NiO–SDC as anode, thin SDC as electrolyte, and SSCo as cathode on porous stainless steel substrate. The anode and electrolyte layers were consecutively deposited onto porous metal substrate by thermal spray, using standard industrial thermal spray equipment, operated in an open-air atmosphere. The cathode materials were applied to the as-sprayed half-cells by screen-printing and heat-treated at 800 °C for 2 h. The cell components and performance were examined by scanning electron microscopy (SEM), X-ray diffraction, leakage test, ac impedance and electrochemical polarization at temperatures between 500 and 700 °C. The half-inch button cells exhibit a maximum power density in excess of 0.50 W cm −2 at 600 °C and 0.92 W cm −2 at 700 °C operated with humidified hydrogen fuel, respectively. The half-inch button cell was run at 0.5 A cm −2 at 603 °C for 100 h. The cell voltage decreased from 0.701 to 0.698 V, giving a cell degradation rate of 4.3% kh −1. Impedance analysis indicated that the cell degradation included 4.5% contribution from ohmic loss and 1.4% contribution from electrode polarization. The 5 cm × 5 cm cells were also fabricated under the same conditions and showed a maximum power density of 0.26 W cm −2 at 600 °C and 0.56 W cm −2 at 700 °C with dry hydrogen as fuel, respectively. The impedance analysis showed that the ohmic resistance of the cells was the major polarization loss for all the cells, while both ohmic and electrode polarizations were significantly increased when the operating temperature decreased from 700 to 500 °C. This work demonstrated the feasibility for the fabrication of metal-supported SOFCs with relatively high performance using industrially available deposition techniques. Further optimization of the metal support, electrode materials and microstructure, and deposition process is ongoing.