Toward Understanding of Temperature Dependence of an Advanced Ceramic Fuel Cell with Ni_0.8Co_0.15Al_0.05LiO₂as an Electrode

Ceramic fuel cells with Gd0.1Ce0.9O1.95 (GDC) as an electrolyte and Ni0.8Co0.15Al0.05LiO2 (NCAL)-coated foam Ni as a symmetric electrode are prepared. The effect of initial reduction temperature of the NCAL anode on the performance of the cells is investigated. When the initial test temperatures of the three cells were 550, 500, and 450 °C, respectively, the maximum power densities of the three cells at 450 °C were 0.221, 0.125, and 0.02 W·cm-2, respectively. At 450 °C, the ionic conductivities of the electrolytes in the cells with three different initial reduction temperatures were 0.288 (550 °C), 0.165 (500 °C), and 0.011 S·cm-1 (450 °C), respectively. During the test, LiOH/Li2CO3 produced by H2 reduction of the NCAL anode diffuses into the GDC electrolyte, and the interface between LiOH/Li2CO3 and GDC becomes the main channel of ion conduction. The scanning electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction results indicated that the amount and the diffusion rate of the LiOH/Li2CO3 mixture diffused into the GDC electrolyte increased with the increase of initial reduction temperature. The LiOH/Li2CO3 mixture entering into the electrolyte will directly affect the effective area or the length of the ion conduction channel formed by the LiOH/Li2CO3 mixture and GDC in the electrolyte, thus significantly affecting the electrochemical performance of the cells.