La0.8Sr0.2Ga0.8Mg0.2O2.8的电化学性质及其在SOFC中的应用

采用凝胶浇注法制备具有较高氧离子电导率的固体电解质La0.8Sr0.2Ga0.8Mg0.2O2.8粉料.X射线衍射结果表明,于1400℃焙烧后即形成了钙钛矿结构,无杂相存在.探讨了粉料压制坯体的致密化和导电性能在1450℃下与烧结时间的关系,发现烧结时间为18h时其相对密度达98.3%,而在24h的情况下,样品具有最佳的氧离子导电性.采用Ni-Ce0.8Gd0.2O1.9作为阳极,La0.8Sr0.2Ga0.6Ni0.4O2.7作为阴极,组装了平板型固体氧化物燃料电池(SOFC).阳极和阴极分别通入含3%H2O的氢气和空气,750℃时的开路电压为1.04V,最大输出功率密度(P)达252mW/cm2(U=0.48V,J=525mA/cm2).

Electrochemical Properties of La0.8Sr0.2Ga0.8Mg0.2O2.8 Electrolyte and Its Application to SOFCs

Sr- and Mg-doped LaGaO3(La0.8Sr0.2Ga0.8Mg0.2O2.8) powders have been successfully synthesized from carbonate and oxides based on the principle of gelcasting. XRD patterns indicate the perovskite structure is formed without any second phases after sintering the powders at 1 400 ℃ for 6 h. The pellet sample was sintered to 98.3% of theoretical density at 1 450 ℃ for 18 h. The total electrical conductivity was greatly depended on the sintering time, and reached the maximum when the pellet was sintered at 1 450 ℃ for 24 h. Planar SOFC was constructed using Ni-Ce0.8Gd0.2O1.9 and La0.8Sr0.2Ga0.6Ni0.4O2.7 as the anode and cathode, respectively. When humidified hydrogen and air were introduced to the two electrodes, maximum power density of 252 mW/cm2(U=0.48 V, J=525 mA/cm2) was achieved with the open circuit voltage of 1.04 V at 750 ℃.