Al_2O_3电解质新型结构SOFC制备及性能研究

Preparation and Electrochemical Performance of a New Structured Low Temperature SOFC with Al_2O_3 Electrolyte

本文主要研究了以Al_2O_3为电解质的新型结构低温固体氧化物燃料电池。分别以三种不同结构的氧化铝(α-Al_2O_3、β-Al_2O_3和含有一定γ相的α-Al_2O_3)为电解质制备了结构为:泡沫镍-Ni_(0.8)Co_(0.15)Al_(0.05)LiO_2(NCAL)/Al_2O_3/NCAL-泡沫镍的SOFC,并在H_2燃料中测试了电化学性能。研究发现三种电池开路电压和最大输出功率密度都有明显差异。α-Al_2O_3、β-Al_2O_3和含有一定γ相的α-Al_2O_3电解质电池在550℃下H_2/air气氛中的开路电压分别为:1.057V、0.415V和0.945V;三种电池的最大功率密度分别为173.44mW·m^(-2)、3.76mW·m^(-2)和99.11mW·m^(-2)。交流阻抗谱结果显示α-Al_2O_3的离子电导率最高,为0.17S·cm^(-1)。通过Ce_(0.9)Gd_(0.1)O_2(GDC)/Al_2O_3双层电解质电池的离子过滤实验发现Al_2O_3电解质中的载流子包含氧离子。对不同结构Al_2O_3粉体材料及其在电池中电化学性能测试前后表面氧元素的结合能的XPS表征结果研究发现:不同结构的Al_2O_3的离子电导率大小跟其表面氧空位浓度有关,氧空位浓度越大,离子电导率越高。Al_2O_3的表面氧空位浓度在氢气通入后也会显著增加。界面氧离子传导应该是这种以氧化铝为电解质的新型结构SOFC的氧离子传导机理。

In this study,a new type of low temperature solid oxide fuel cell(LT-SOFC)using Al2O3 as electrolyte is studied.SOFCs with a structure of foam Ni-Ni0.8Co0.15Al0.05LiO2(NCAL)/Al2O3/NCAL-foam Ni was prepared.Three different structures of alumina(α-Al2O3,β-Al2O3 andα-Al2O3 containing a certain amount ofγphase)were used as electrolyte,respectively.The electrochemical performance of the cell was tested in the H 2 fuel.It is found that the open circuit voltage and the maximum power density of the three cells with different Al2O3 electrolyte are obviously different.The OCV of the cell withα-Al2O3,β-Al2O3 andα-Al2O3 containing a certain amount ofγphase electrolyte was 1.057,0.415 and 0.945 V,respectively.The corresponding maximum power density of the cell withα-Al2O3,β-Al2O3 andα-Al2O3 containing a certain amount ofγphase electrolyte was 173.44,3.76 and 99.11 mW/cm 2,respectively.EIS result indicates that the ionic conductivity ofα-Al2O3 electrolyte prepared in present case is as high as 0.17 S/cm.Through the ion filtration experiment of the cell with Ce0.9Gd0.1O2(GDC)/Al2O3 double layer electrolyte,it is found that the carrier of Al2O3 electrolyte contain oxygen ions.X-ray photoelectron spectroscopy(XPS)results indicate that the ionic conductivity of different structures of Al2O3 was related to the oxygen vacancy concentration on the surface.The surface oxygen vacancy concentration of Al2O3 electrolyte was significantly increased in the fuel cell test atmosphere.The higher the oxygen vacancy concentration on the surface of the Al2O3 electrolyte,the better the cell performance.We speculate that the oxygen conduction in the interface should be the oxygen ion conduction mechanism of this new structure SOFC with alumina as electrolyte.