Electrochemical studies on the oxygen reduction and NiO(Li) dissolution in molten carbonate fuel cells
Abstract
A study of the oxygen reduction in molten carbonate on a plane gold electrode submerged in a molten carbonate melt and on three different porous electrodes, made of NiO(Li), LiFeO2 (doped with either Mg or Co) and LiCoO2, is presented. From the impedance measurements made on plane gold electrode, two parallel reaction mechanisms are concluded to be involved in the oxygen reduction: in the first peroxycarbonate is reduced at a partly with oxide covered electrode surface; and in the second the steps could not be unraveled. Partial pressure dependencies of the diffusion arc observed in the impedance of the porous electrodes indicate that both oxygen and carbon dioxide are the diffusing species. From comparison of the ratios of the diffusion and kinetic arc, the catalytic activities of the three materials are concluded not to differ significantly, although this seems to be contradictory to the observation that the impedance for Co doped LiFeO2 is much Larger than for the other materials. This difference, however, is due to the large specific resistivity of Co doped LiFeO2 compared to the resistivity of the other materials.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- 1991
- Bibcode:
- 1991PhDT........27M
- Keywords:
-
- Deoxidizing;
- Electrolysis;
- Fuel Cells;
- Lithium Compounds;
- Melts (Crystal Growth);
- Nickel Compounds;
- Carbonates;
- Cobalt Compounds;
- Electrical Impedance;
- Electrode Materials;
- Gold;
- Molten Salts;
- Oxygen;
- Reduction (Chemistry);
- Solid-State Physics