科研之友
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摘要
The electrochemical performance and durability of solid oxide fuel cells strongly depend on the oxygen electrode due to its dominant contributions to the cell resistance, but most of convectional cathode materials suffer from high polarization, chemical instability, temperature-dependent conductivity and vulnerability to Cr-based interconnects. A Fe-based perovskite oxide BaFe0.75Ni0.25O3-delta (BFNi25) has been prepared by a glycine-nitrate method and evaluated as novel cathode material for solid oxide fuel cells (SOFCs). When tested as potential cathode, BFNi25 showed an excellent thermal stability and chemical compatibility with Ce0.9Gd0.1O1.95 (CGO) electrolyte. The oxygen non-stoichiometry of BFNi25 at elevated temperatures was systematically investigated through thermo-gravimetric analysis and iodometric titration data. The BFNi25 cathode exhibited a polarization resistance of 0.095 Omega cm(2) at 700 degrees C in air. The maximum power density of a single cell based on the BFNi25 cathode reached 1.15, 0.74 and 0.42 W cm(-2) at 700, 650 and 600 degrees C, and 100 h aging test at 0.5 V confirmed its favorable stability. In addition, study of oxygen partial pressure dependence on the polarization resistance indicated that the rate-limiting step for ORR on the electrode is the charge transfer process. The exhibited electrochemical performance demonstrates that BFNi25 can be a promising cathode material candidate for intermediate-temperature SOFCs.
