Electrode Kinetics of Oxygen Reduction in Lithium Carbonate Melt: Use of Impedance Analysis and Cyclic Voltammetric Techniques to Determine the Effects of Partial Pressure of Oxygen

The effects of the partial pressure of oxygen and temperature on the oxygen reduction on a submerged gold electrode in a lithium carbonate melt were investigated using cyclic voltammetry and impedance analysis. The values for the mass-transfer parameters, D~eCo, obtained from cyclic voltammetry and impedance analysis were in good agreement. The reac-tion orders for oxygen at 800 ~ were calculated to be about 0.3 for the exchange current density and 0.5 for the product 1/2. Do Co, these values are consistent with the mechanism proposed in the literature for oxygen reduction in LiaCO3 melt. An elucidation of the oxygen reduction reaction in molten alkali carbonate is essential because overpotential losses in the molten carbonate fuel cell are considerably greater at the oxygen cathode than at the hydrogen anode. Appleby and Nicholson (1-4) examined the oxygen reduc-tion reaction in molten carbonates on a submerged gold electrode using steady-state and potential scan tech-niques. They observed that oxygen dissolves chemically i