| Solid oxide fuel cells (SOFCs) are solid-state electrochemical device that convert the chemical energy of reaction directly into electrical energy. It possesses several distinct advantages, such as environmental friendship, higher conversion efficiency and broad adaptive fuels, which is a new green energy developed in the world for 21 century. It was reported that the solid electrolyte, strontium- and magnesium-doped lanthanum gallate (LSGM) exhibited superior oxygen ionic conductivity at intermediate temperatures over a broad range of oxygen partial pressures. Moreover, it was found that the oxide ion conductivity was also improved by doping Co for Ga in LaGaO3-based perovskites, although the hole conduction was introduced at high oxygen partial pressures. However, the basis of anode NiO would react with electrolyte LSGM at the high temperature. The formed higher resistive LaNiO3-based compound can block the transport of oxide ion from the electrolyte to the anode and increase interfacial resistance. And the LaNiO3-base compound would manifold with the increase of the firing temperature. Therefore, it is a critical technology to avoid the reaction between Ni in the anode and La in the electrolyte for improving the performance of LaGaO3-based SOFCs. Two methods were employed to achieve the global target. The one was to introduce a SDC buffer between the anode substrate and LSGMC electrolyte film to prohibit the reaction between LSGMC and NiO. The other was to reduce the sintering temperature of anode to avoid Ni of anode reaction with La of LSGM electrolyte,The LSGMC film was prepared on NiO/SDC anode support with a SDC buffer by a dry press process. The results show that the perovskite phase in the LSGMC powders synthesized by GNP was formed by sintering at 1200℃for 6h. However, the impurity phase SrLaGa3O7 andSrLaGaO4 is also observed. The introduction of an interlayer of SDC between the anode and the LSGMC electrolyte effectively prevented the chemical reaction between them. The conductivities of the LSGMC electrolyte film sintered at 1400℃for 6h attains 0.189 and 0.235 S/cm at 800 and 850℃, respectively. For the LSGMC electrolyte film obtained from the powders calcined at 1300℃, the grain boundaries tend to merge. Meanwhile, for the LSGMC electrolyte film obtained from the powders calcined at 1200℃, the LSGMC grains are not well sintered. The contact between grains is close, but no amalgamation between grains is observed, and the obvious holes are observed on the film. This indicates that the LSGMC electrolyte film can be well sintered using the powders calcined at 1300℃. So, the performance of the LSGMC film cell made from the powders calcined at 1300℃was higher than that of 1200℃. And the single cell presented a maximum power density of 232.6 and 243.8 mW/cm2at 850℃and 900℃, respectively.To reduce the sintering temperature of anode to avoid the reaction between Ni in the anode and lanthanum in the LaGaO3-based electrolyte, the nano-particle NiO and GDC powders were synthesized using a glycine-nitrate process (GNP). The results show that the average crystallite sizes of NiO and GDC powders synthesized by GNP calcined at 600 oC are 103.1 and 13.4 nm, respectively. The TEM image shows that the grain size of NiO powders calcined at 600℃is about 20-60 nm with slight agglomerates. The average grain size of the GDC powders calcined at 600 oC is about 4-8 nm with some agglomeration. The particle size determined by TEM is smaller than that by the XRD results. It was also found that Ni phase was detected in the NiO precursor powders synthesized by GNP. The small amount of Ni was transformed into NiO after calcining at 600℃. The LSGM electrolyte layer is very dense and impermeable, and the anode is well adhered to the electrolyte layer without any crack or delamination between them. However, it is observed that the porosity of the NiO/GDC composite anode sintered at 1100 oC is very low. No any Ni component can be detected in the LSGM electrolyte from the EDX spectroscopy. This indicates that the diffusion of Ni from anode to electrolyte and the reaction between anode NiO and electrolyte LSGM could be avoided by decreasing the sintering temperature of anode. The impedance spectroscopy results show that the ohmic resistances and polarization resistances are 0.63 and 0.13?·cm2 at 850℃, respectively. The ohmic resistances account for a larger part of the total resistances, the cell performance is essentially dominated by the ohmic resistance. The maximum power density of cell achieves 300 and 487 mW / cm2 at 800 and 900℃, respectively. The cell performance is significantly superior to that of NiO/LSGM, NiO/CeO2,La0.9Sr0.1Ga0.8Mn0.2O3 and LSCM anodes. The long term stability of LSGM cell using nano-sized NiO/GDC as anode will remain to further investigate in the feature.
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