MCFC

New mechanisms of oxygen reduction on perovskite related oxides LaL_i0.1M_0.1Fe_0.8O_3-d (M = Fe, Co, Ni) and a rock salt type oxide Li_0.1Ni_0.9O have been proposed. Based on these mechanisms, a comparison of catalytic activity of the oxides in the temperature range 820–1000 K has been done. It has been shown that catalytic activity of LaLi0.Co0.1Fe0.8O3-d oxide exceeds the activity of Li0.1Ni0.9O below 970 K

This paper presents polarization characteristics of porous gas diffusion cathodes prepared from LaLi0.1M0.1Fe0.8O3-d (M = Fe, Co, Ni) oxides with a perovskite related structure and Li0.1Ni0.9O oxide with a rock salt structure. The characteristics were measured in the laboratory scale fuel cell in the temperature range 820–1000 K. It has been shown that electrochemical activity of the cathodes with Co and Ni additives exceeds the activity of the Li0.1Ni0.9O cathode below 970 K.

The oxygen reduction mechanisms on an oxide electrode are proposed. It was found, that in the temperature range 870–1020 K mechanism involving superoxide ions dominates, whereas in T < 870 К region the reaction mechanisms involving molecular oxygen apparently take place.

The results of the study of kinetics of oxygen reduction on the dense LaLi_0.1Co_0.1Fe_0.8O_3-d electrode in (Li_0.62K_0.38)₂CO₃ eutectic melt using coulostatic technique are reported. It was found, that the equivalent circuit that includes heterogeneous charge transfer step in series with heterogeneous chemical reaction most closely fits the kinetics of electrode processes.