过渡层对掺Al_2O_3的YSZ电解质支撑SOFC的影响

Influence of Buffer Layer on Performance of SOFC Supported by Al_2O_3-Doped YSZ Electrolyte

采用甘氨酸-硝酸盐燃烧法合成阳极材料NiO以及阴极材料La0.8Sr0.2MnO3(LSM),分别将电解质YSZ(8%(摩尔分数)氧化钇稳定氧化锆)和掺4%Al2O3的YSZ压片后在1450℃下烧结4h,在掺Al2O3电解质的阳极侧涂刷过渡层后于1200℃烧结1h.以加湿氢气(含3%H2O)为燃料、环境空气为氧化剂,测试3种电池的输出性能和交流阻抗谱.结果表明:850℃时,含Al2O3的电池输出性能最差,输出功率约为0.083 W/cm2;含Al2O3并具有过渡层的电池输出性能最好,输出功率约为0.120 W/cm2;交流阻抗谱分析表明,含Al2O3并具有过渡层的电池的欧姆电阻与界面电阻均比不含过渡层的明显减小,说明YSZ中添加的Al2O3在高温烧结过程中,与阳极材料NiO发生反应生成不导电的镍铝尖晶石.过渡层的存在,不仅保留了Al2O3对电解质的贡献,也抑制了不导电的镍铝尖晶石的生成.

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 Al2O3 -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 AI： 03 （ 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 Al2O3 and NiO during the sintering at a high temperature. Therefore, the application of buffer layer not only keeps the contribution of Al2O3 to the electrolyte but also reduces the generation of insulative nickel aluminum spinel.