| Solid oxide fuel cell is an efficient and green energy conversion device, the electrolyte has attracted much attention as the center component. In recent years, the development trend of SOFC is to reduce the operating temperature to intermediate temperature, thus resulting in the more wants for the electrolyte material. An important factor of limiting the application for ceria-based electrolyte is the poorer sintering property. Some studies has found that the electrical conductivity of Nd and Sm co-doped ceria is higher than that obtained in either Nd or Sm single-doped ceria, while the transition metal oxide can be used as a sintering aid. In this paper, we may investigate the influence of the doping of transition metal Fe, Co, Ni, Zn on the Nd and Sm co-doped ceria -Nd0.1Sm0.1Ce0.8O1.9, respectively.Sm0.1Nd0.1Ce0.8O1.9 (SNDC) and Sm0.1Nd0.1Ce0.79Mo.01O1.9-δ (M=Fe, Co, Ni, Zn) powders were synthesized via a citric-nitrate combustion process. The phase, microstructure, sinteing property, electrical conductivity, and output properties of the electrolyte materials were characterized by XRD, SEM, Archimedes method, EIS, thermal expansion measurement and the cell testing system.The XRD patterns of the calcined SNDC and SNDCM (M=Fe, Co, Ni, Zn) powders prepared by citric-nitrate combustion process and treated at 700℃ for 3 h, exhibit a single phase with a cubic fluorite structure,without the second phase, which is meant that the doping of the transition metal Fe, Co, Ni, Zn cannot change the struture of Sm0.1Nd0.1Ce0.8O1.9.The research of the preparation and properties of rare earth Nd and Sm co-doped CeO2 electrolyte material:The higher sintering temperature leads to the growth of the average grain size and the reduction of the pinholes. When the sintering temperature reaches 1350℃, the ceramic is very dense and the electrical conductivity reaches the highest. The average thermal expansion coefficient of SNDC is 13.7×10-6 K-1 temperature range from 100℃ to 1000℃, which is close to SDC. Ni-SNDC|SNDC|SBCO-SNDC, the anode-supported cell, while the bi-layer co-pressed with dense SNDCFe film and porous anode brace was obtained by co-sintering at 1250℃ in air for 5 h, was fabricated and tested by using humidified (3% H2O) hydrogen as fuel and static air as oxidant. The open circuit voltage (OCV) of 0.71 V, maximum power density of 372 mW/cm2 and the ohmic resistance of 0.3 Ω·cm2 were obtained at 650℃.The research of the preparation and properties of transition metal Fe-doped Ce0.8Sm0.1Nd0.1O1.9 electrolyte material:When the sintering temperature reaches 1250℃, the ceramic has the highest relative density, the highest grain boundary conductivity and lower activation energy. The grain and grain boundary conductivity of SNDCFe sintered at 1250℃ are higher than the SNDC ceramic sintered at 1300℃. The average thermal expansion coefficient of SNDCFe is 13.9×10-6 K-1 at temperature range from 100℃ to 1000℃, which is close to SNDC. Ni-SNDC|SNDCFe|SBCO-SNDC, the anode-supported cell, while the bi-layer co-pressed with dense SNDCFe film and porous anode brace was obtained by co-sintering at 1250℃ in air for 5 h, was fabricated and tested by using humidified (3% H2O) hydrogen as fuel and static air as oxidant. The open circuit voltage (OCV) of 0.78 V, maximum power density of 458 mW/cm2 and the ohmic resistance of 0.384 Ω·cm2 were obtained at 650℃. It indicated that the SNDCFe electrolyte could be a potential candidate for IT-SOFCs.The research of the preparation and properties of transition metal Co-doped Ce0.8Sm0.1Nd0.1O1.9 electrolyte material:When the sintering temperature reaches 1100℃, the ceramic has the highest relative density, the highest grain boundary conductivity and lower activation energy. The conductivity of SNDCCo is close to the SNDC ceramic sintered at 1300℃. The average thermal expansion coefficient of SNDCCo is 13.8×10-6 K-1 at temperature range from 100℃ to 1000℃, which is close to SNDC.Ni-SNDC|SNDCCo|SBCO-SNDC, the anode-supported cell, while the bi-layer co-pressed with dense SNDCCo film and porous anode brace was obtained by co-sintering at 1250℃ in air for 5 h, was fabricated and tested by using humidified (3% H2O) hydrogen as fuel and static air as oxidant. The open circuit voltage (OCV) of 0.78 V, maximum power density of 452 mW/cm2 and the ohmic resistance of 0.276 Ω·m2 were obtained at 650℃. It indicated that the SNDCCo electrolyte could be a potential candidate for IT-SOFCs.The research of the preparation and properties of transition metal Ni-doped Ce0.8Smo.iNd0.1O1.9 electrolyte material:When the sintering temperature reaches 1200℃, the ceramic has the highest relative density and the highest grain boundary conductivity. The grain boundary conductivity of SNDCNi sintered at 1200℃ is much higher than the SNDC ceramic sintered at 1300℃. The average thermal expansion coefficient of SNDCNi is 14.6×10-6 K-1 at temperature range from 100℃ to 1000℃, which is close to SNDC. Ni-SNDC|SNDCNi|SBCO-SNDC,the anode-supported cell, while the bi-layer co-pressed with dense SNDCNi film and porous anode brace was obtained by co-sintering at 1250℃ in air for 5 h, was fabricated and tested by using humidified (3% H2O) hydrogen as fuel and static air as oxidant. The open circuit voltage (OCV) of 0.78 V, maximum power density of 331 mW/cm2 and the ohmic resistance of 0.402 Ω·m2 were obtained at 650℃.The research of the preparation and properties of transition metal Zn-doped Ce0.8Sm0.1Nd0.1O1.9 electrolyte material:When the sintering temperature reaches 1100℃, the ceramic has the highest relative density and the highest grain boundary conductivity. The grain boundary conductivity of SNDCZn sintered at 1100℃ is higher than the SNDC ceramic sintered at 1300℃. The average thermal expansion coefficient of SNDCZn is 13.9×10-6 K-1 at temperature range from 100℃ to 1000℃, which is close to SNDC. Ni-SNDC|SNDCZn|SBCO-SNDC, the anode-supported cell, while the bi-layer co-pressed with dense SNDCZn film and porous anode brace was obtained by co-sintering at 1250℃ in air for 5 h, was fabricated and tested by using humidified (3% H2O) hydrogen as fuel and static air as oxidant. The open circuit voltage (OCV) of 0.75 V, maximum power density of 413 mW/cm2 and the ohmic resistance of 0.328 Ω·cm2 were obtained at 650℃. It indicated that the SNDCZn electrolyte could be a potential candidate for IT-SOFCs. |
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