Electrochemical performance of Li1-xNaxNi0.8Al0.2O2 as symmetrical electrode for low temperature ceramic fuel cells

This paper investigates the electrochemical performance of LixNa1-xNi0.8Al0.2 (x = 0.1, 0.2, 0.3, 0.4, LNNA) with different ratios of Na doping as electrode materials for ceramic fuel cells. It is found that the maximum power density (MPD) of the ceramic fuel cells prepared by co-pressure method with LNNA as symmetrical electrodes and GDC as electrolyte gradually decreases with the increase of Na doping in LNNA in H-2 at 550 degrees C. The MPD for the cell with LNNA-91 electrode reaches 718 mW center dot cm(-2), while that of the cell with LNNA-64 electrode is 503 mW center dot cm(-2). However, this MPD values still have strong competitiveness in the fuel cells operating at temperature around 550 degrees C. It was found that the LNNA anode is reduced by H-2, generating LiOH/NaOH molten salts, which diffuse into the GDC electrolyte and form a "GDC-Li/Na compounds" composite electrolyte with exceptional ionic conductivity. This is the key factor contributing to the excellent electrochemical performance of these ceramic fuel cells. The increase of Na content in LNNA will destroy its phase structure and generate new phases such as NaCO3, resulting in the degradation of the electrode performance. Therefore, the doping amount of Na in LNNA needs to balance the cost and performance of the cell.