Impedance analysis for oxygen reduction in lithium carbonate melt: Effect of partial pressure of oxygen

摘要

Effects of partial pressure of oxygen and temperature on oxygen reduction kinetics on a submerged gold electrode in lithium carbonate melt were investigated using cyclic voltammetry and impedance analysis. Cyclic voltammetry measurements indicated that the oxygen reduction reaction in Li(sub 2)CO(sub 3) melt is reversible up to 200 mV/s. The impedance analysis was carried out using a Complex Nonlinear Least Square (CNLS) paxameter estimation program based on the Randles-Ershler equivalent circlet. This analysis technique was used to estimate the electrode kinetics and the mass transfer related parameters such as the charge transfer resistance (R(sub ct)) and the Warburg coefficient (sigma). The mass transfer related parameters obtained from cyclic voltammetry and impedance analysis were in good agreement. The reaction orders for oxygen at 800(degrees)C were calculated to be 0.38 for the exchange current density and 0.5 for the product D(sub o)(sup (1 /2))C(sub o)*; these values are consistent with the mechanism proposed in the literature for oxygen reduction in Li(sub 2)CO(sub 3) melt on a submerged gold electrode.