Carbon deposition in porous nickel/yttria-stabilized zirconia anode under methane atmosphere

A commercial solid oxide fuel cell with a Ni/YSZ anode was characterized under a pure methane atmosphere. The amount of deposited carbon increased with an increase in temperature but decreased when the temperature exceeded 700°C. The reactivity of carbon decreased with increasing deposition temperature. Filamentous carbon was deposited from 400 to 600°C, whereas flake carbon was deposited at 700 and 800°C. With increasing temperature, the intensity ratio of the D band over the sum of the G and D bands was constant at the beginning and then decreased with the transformation of the carbon morphology. The crystallite size increased from 2.9 to 13 nm with increasing temperature. The results also indicated that the structure of the deposited carbon was better ordered with increasing deposition temperature. In comparison with pure Ni powders, the interaction between the YSZ substrate and Ni particles could not only modify the carbon deposition kinetics but also reduce the temperature effect on the structure and reactivity variation of carbon.

Electrochemical property of multi-layer anode supported solid oxide fuel cell fabricated through sequential tape-casting and co-firing

In this work, a multi-layer anode supported solid oxide fuel cell(SOFC) is designed and successfully prepared through sequential tape casting and co-firing. The single cell is consisted of NiO-3 YSZ(3 YSZ: 3 mol.% yttria doped zirconia) anode support, NiO-8 YSZ(8 YSZ: 8 mol.% yttria stabilized zirconia) anode functional layer, dense 8 YSZ electrolyte layer, and porous 3 YSZ cathode scaffold layer with infiltrated La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) cathode. The clear interfaces and good contacts between each layer, without element inter-diffusion being observed, suggest that this sequential tape casting and co-firing is a feasible and successful route for anode supported single cell fabrication. This cell exhibits remarkable high open circuit voltage of 1.097 V at 800?C under room temperature humidified hydrogen, with highly dense and gastight electrolyte layer. It provides a power density of 360 mW/cm^2 under operation voltage of0.75 V at 800?C and a stable operation of ～110 h at 750?C under current density of-300 mA/cm^2. Furthermore, this cell also presents encouraging electrochemical responses under various anode hydrogen partial pressures and maintains high power output at low fuel concentrations.

Performance and stability analysis of SOFC containing thin and dense gadolinium-doped ceria interlayer sintered at low temperature

Gadolinium-doped ceria(GDC)interlayers are required to prevent the interfacial reaction between La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3)(LSCF)cathode and Y_(2)O_(3)-stabilized ZrO 2(YSZ)electrolyte in solid oxide fuel cells(SOFCs).However,it's difficult to prepare a thin and dense GDC interlayer on the sintered half-cell at a low temperature.In this study,the physical vapor deposition(PVD)method was employed to success-fully manufacture dense GDC interlayers with the thickness of 1 m m.The influences of GDC sintering temperature(900℃,1000℃ and 1100℃)on cell performance characteristics and degradation behavior were investigated.The cell with GDC interlayer sintered at 1100?C showed the lowest degradation rate during the 216-h operation.The best stability was attributed to the most effective inhibition of Sr diffusion by the GDC interlayer,which was demonstrated by the almost unchanged Ohmic and polari-zation resistances during the aging stage and the negligible Sr enrichment at YSZ/GDC interface.Compared to the conventional screen-printed GDC interlayers(sintered above 1250℃),the GDC inter-layer prepared by the PVD method and sintered at 1100℃ was significantly denser and thinner,showing a promising application prospect due to its benefits for cell stability.