The Preparation And Study On SOFC's Cathode

Solid Oxide Fuel Cell (SOFC), as a new way of power generation, exhibits a great potential in solution of energy crisis and environmental pollution, and gets a wide attention in recent years. As an candidate of SOFC's cathode, perovskite oxides have been focused on widely,but there is no the agreement in technical factors and further research about new materials is necessary.La0.7Sr0.3MnO3 and Sr1-xCexCoO3－( materials were synthesized by solid reaction and sol-gel combustion method respectively in this paper. Many factors affecting the properties of powder, sintering density and electrical performance were investigated. For La0.7Sr0.3MnO3, the single perovskite phase of powder synthesized by solid reaction method was detected to exist after calcining at 1000℃, however, the perovskite phase appeared after combustion for the powder synthesized by sol-gel combustion method. By contrast, a 700℃ decreased in formation temperature of the perovskite phase between the both methods occurred. For combustion technology, the pH of sol should be adjusted below 3.0 to ensure the good complexing. The particle size decreased and sintering density increased with increasing the content of citric acid, and the formation of pervoskite was not visibly affected by it. On the conductivity and polarization, the samples prepared by combustion way was worse than by solid reaction.For Sr1-xCexCoO3－(, the temperature of forming perovskite was 1100℃ by solid reaction way, and 1000℃ by sol-gel combustion method. The dopant of CeO2 was below 15%. For combustion method, the pH of sol was under 3.5, and the perovskite did not occur after combustion, but was formed after post heat treatment at 1000℃, a slight decrease compared to the former. It could be seen through TEM analysis that the particle size by combustion was smaller than that by solid reaction. The degree of crystallization increased with increasing content of citric acid. The density raised with sintering temperature. the conductivity was affected by microstructure strongly, and exhibits the highest for samples sintered at 1300℃. The density and conductivity through combustion also was higher than through solid reaction. By contrast, the highest conductivity of Sr0.85Ce0.15CoO3－( was more than 500S/cm, higher than that of La0.7Sr0.3MnO3, which suggested a vantage in conductivity. However, the change of conductivity with temperature was different from that of La0.7Sr0.3MnO3. The former increased with temperature, but the latter decreased after a increasing. On polarization, the sample of Sr0.85Ce0.15CoO3－( was worse than La0.7Sr0.3MnO3, which may be influenced by microstructure and interfacial products.