Study on Electrochemical Performance of CuBi2O4-Gd0.1Ce0.9O1.95 Composite Cathode for Intermediate Temperature SOFCs
Improving the electrochemical performance of SOFC cathode material CuBi2O4(CBO)at medium temperature,Gd0.1Ce0.9O1.95(GDC)phases sintered at different temperatures were added to CBO to prepare corresponding CBOGDC(CG)composite cathodes.The electrochemical properties of the cathodes were characterized and analyzed by AC impedance spectroscopy.The effects of microstructure and addition of GDC phase on the electrochemical performance of the composite cathode and its mechanism were investigated,and the optimum sintering temperature of the added GDC phase and the best ratio of CBO and GDC phase in the composite cathode were determined.The results show that the sintering temperature selected in the synthesis process of GDC powder affects its microstructure,which in turn affects the electrochemical performance of the composite cathode.The addition of GDC phase sintered at 800 ℃ can effectively improve the electrochemical performance of CBO cathode compared with GDC sintered at other temperatures.In addition,when the addition of GDC phase is 40 wt.％,the electrochemical performance of the composite cathode is the best,and the polarization resistance is the lowest.The polarization resistance Rp are 0.70,0.39,0.21 Ω·cm2 at 650 ℃,700 ℃ and 750 ℃,respectively.According to the analysis of characteristic capacitance,activation energy and reaction order,it is concluded that the charge transfer process is the main rate control step of oxygen reduction reaction of composite cathode.
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