Electrochemical performance of La_2NiO_(4+δ)-La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) composite cathodes for intermediate temperature solid oxide fuel cells

摘要

The composite cathodes La_2NiO_(4+δ)-La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) were prepared for intermediate temperature solid oxide fuel cells. La_2NiO_(4+δ) and La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) powders were synthesized successfully by glycine-nitrate process. The effect of composition on the electrochemical performance of the composite electrodes was studied by AC impedance spectroscopy and the optimal calcination temperature was determined when the electrode showed the minimum area specific resistance. The addition of La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) to La_2NiO_(4+δ) electrode decreased the area specific resistance remarkably. The composite electrode with 30wt% La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) calcined at 1150 ℃ exhibited the lowest area specific resistance of 0.125 Ωcm~2, about 60% of the area specific resistance of La_2NiO_(4+δ) electrode at 700 ℃ in air. The composite electrode with 30 wt% La_(0.6)Sr_(0.4)Co_(0.2)Fe_(0.8)O_(3-δ) can be a promising cathode material through the evaluation of electrical conductivity and thermal expansion behavior.