Electrical Performance Of Ag-Based Ceramic Composite Electrodes And Their Application Research In Solid Oxide Fuel Cells

Solid oxide fuel cell(SOFC) has emerged as one of the most important power generation technologies because of its high energy conversion efficiency, low noise and low pollution. The electrode materials of SOFC influence the performances of cells dominantly. Currently, Ni-yttria stabilized zirconia(Ni-YSZ) cermet is the most commonly used anode material for SOFCs from the view of a reasonable balance among the requirements. However, the problem that Ni catalyzes carbon deposition reactions, resulting in catastrophic fracture of the anode, has been always hindering the development of SOFC in practical use. The oxygen reduction ability of LSM cathode is powerless, its cathode polarization impedance is very large especially at low temperature, both of them result in the bad performances of SOFC.This paper research on the performance of Ag-based ceramic composited material as the anode and cathode of SOFC, aiming to solve the problem of traditional electrode. Respectively, Ag-GDC and Ag-YSZ with different ratio are used as electrode materials to make symmetric electrodes on the YSZ electrolyte pellets. Impedance spectras are measured in an ambient atmosphere to research their performances as cathode materials. It was found that Ag-YSZ has the lowest polarization resistance when the content of Ag is 65%(w, mass fraction), while that for Ag-GDC, the value is 70%(w, mass fraction). The OCV and maximum power density(Pmax) of the SOFC with 65Ag-YSZ used as anode and cathode materials operated on humidified hydrogen(3%) are 1.08 V, 200 mW·cm-2 at 800 ?C and it achieves 1.09 V, 214 m W·cm-2 when the SOFC with 70Ag-GDC. As shown in the impedance spectras, although the polarization resistance of Ag-YSZ is lower than that of Ag-GDC in the air, the polarization resistance of Ag-GDC is larger than that of Ag-YSZ when the humidified hydrogen(3%) is used as fuel.According to the former research, the performance of Ag-based ceramic composited material for the DC-SOFC have already been studied. The maximum power density(Pmax) is ~339 mW·cm-2 at 830 ?C when 65Ag-GDC and 65Ag-YSZ were used as anode and cathode in DC-SOFC, respectively. It is apparent that 65Ag-GDC is the suitable anode materials for the DC-SOFC.