Ba1.03Ce0.9-xZrxTm0.1O3-α固体电解质的化学稳定性和电性能

摘要

用高温固相反应法制备了非化学计量组成的Ba1.03Ce0.9-xZrxTm0.1O3-α(x=0.2,0.4)固体电解质.分别用粉末X-射线衍射(XRD)和扫描电镜(SEM)方法表征了这两种材料的相组成和断面形貌,测定了它们在900℃下,CO2以及水蒸气气氛中的化学稳定性.在500～900℃温度范围内,分别用气体浓差电池方法和交流阻抗谱技术研究了材料在不同气体气氛中的离子导电性,研究了以这两种材料为固体电解质的氢-空气燃料电池性能.结果表明,Ba1.03Ce0.7Zr0.2Tm0.1O3-α材料为单一钙钛矿型斜方晶结构,Ba1.03Ce0.5Zr0.4Tm0.1O3-α材料为单一钙钛矿型立方晶结构.2种材料均具有较高的致密性和化学稳定性.在500～900℃温度范围内、湿润氢气中,Ba1.03Ce0.7Zr0.2Tm0.1O3-α材料表现为纯的离子导电性,而Ba1.03Ce0.5Zr0.4Tm0.1O3-α材料表现为离子和电子的混合导电性;在湿润空气中,两种材料均表现为质子、氧离子和电子空穴的混合导电性;在氢-空气燃料电池条件下,均表现为质子、氧离子和电子的混合导电性.以这两种材料为固体电解质的氢-空气燃料电池均能稳定地工作.在相同实验条件下,Ba1.03Ce0.7Zr0.2Tm0.1O3-α材料的离子导电性及其氢-空气燃料电池性能均高于Ba1.03Ce0.5Zr0.4Tm0.1O3-α材料.%Ba1.03Ce0.9-xZrxTm0.1O3-α(x=0.2,0.4) solid electrolytes with nonstoichiometric composition were prepared by high temperature solid-state reaction.Phase composition and fracture morphologies of the two materials Were characterized by using XRD and SEM,respectively.Chemical stability against carbon dioxide and water steam at 900 ℃ was tested.Ionic conduction was studied by using gas concentration cell and ac impedance spectroscopy methods,and the performances of the hydrogen-air fuel cells using the two materials as solid electrolytes were evaluated in the temperature range of 500～900 ℃.The results indicate that the material with x of 0.2 is a singlephase perovskite-type orthorhombic system,and the material with x of 0.4 is a single-phase perovskite-type cubic system.They both have high density and good chemical stability.In wet hydrogen,Ba1.03Ce0.7Zr0.2Tm0.1O3-α shows a pure ionic conduction,but Ba1.03Ce0.5Zr0.4Tm0.1O3-α shows a mixed conduction of ion and electron from 500 to 900 ℃.The two materials both show a mixed conduction of proton,oxide ion and electronic hole in wet air,and a mixed conduction of proton,oxide ion and electron in hydrogen-air fuel cell.The fuel cells using the two materials as solid electrolytes can both work stably.The ionic conduction and performance of the hydrogen-air fuel cell of Ba1.03Ce0.7Zr0.2Tm0.1O3-α are superior to those of Ba1.03Ce0.5Zr0.4Tm0.1O3-α under the same experimental conditions.