Measuring the Electrode Kinetics of Cathodic Oxygen Reduction with Different Fast and Slow Methods in Alkali Carbonate Melts

摘要

The fast kinetics of cathodic oxygen reduction were measured on flat gold, lithiated nickel oxide and LiCoO_2 electrodes in O_2/CO_2= 30/30 vol. atmosphere. Extrapolating the substrate thickness to zero obtains i_0 of 13 (Au), 13 (LiCoO_2) and 4 (NiO) mA cm~(-2) which for NiO is only half the value of most of the reported data. Slow methods reveal only formal reaction orders of slow transport: 0.78 for O_2 and approx. 0 for CO_2. Discrepancies of slow and fast and in-cell measurements are indicative of the importance of mass transfer for cell operation.