Abstract:

NiO and La0.8Sr0.2 MnO₃ were first synthesized by means of glycine-nitrate combustion method and were respectively used as the anode and the cathode materials of solid oxide fuel cell （SOFC）. Next, YSZ （8% yttriumstabilized zirconia） and the YSZ doped with 4% A1₂0₃ were pressed into wafer and sintered at 1 450 ℃ for 4 h. Then, the anode side of the A1₂0₃  -doped electrolyte was coated with the buffer layer and was further sintered at 1200 ~C for 1 h. Moreover, the output performances and AC impedance spectroscopy of the three kinds of fuel cells were tested, with humid hydrogen containing 3 % H₂0 as the fuel and with the ambient air as the oxidant. The re- sults indicate that the cell only doped with A1₂0₃  （ Cell 1 ） is of the worst output performance at 850 ~C , the output power density being 0. 083 W/cm², and that the cell doped with A1₂0₃  and coated with buffer layer （Cell 2） is of the best output performance at the same temperature, the output power density being 0. 120W/cm². AC impedance spectroscopy analyses indicate that the interface resistance and Ohmic resistance of Cell 2 are obviously less than those of Cell 1, meaning that insulative nickel aluminum spinel is generated by the reaction of A1₂0₃ and NiO during the sintering at a high temperature. Therefore, the application of buffer layer not only keeps the contribution of A1₂0₃  to the electrolyte but also reduces the generation of insulative nickel aluminum spinel.

Key words: solid oxide fuel cell, buffer layer, alumina, doping, electrolyte