KINETICS OF THE OXYGEN-ELECTRODE REACTION IN MOLTEN LI+NA CARBONATE EUTECTIC .5. LINEAR VOLTAMMETRIC AND CHRONOAMPEROMETRIC DATA FOR THE REDUCTION PROCESSES AT NIO MONOCRYSTALLINE ELECTRODES

Oxygen reduction at monocrystalline NiO electrodes in molten Li + Na c arbonate eutectic has been investigated by linear potential scan volta mmetry and potential-step chronoamperometry. The results are compared with analogous data for gold electrodes. For the first reduction step, similar voltammetric and chronoamperometric responses were observed, as in the case of gold electrodes, suggesting that the process is O-2( 2-) + 2e- half arrow right over half arrow left 2O2-. Some differences between the voltammetric characteristics of these processes on Au and NiO have been attributed to ohmic resistances of NiO electrodes. An a dditional electrode process, occurring only on NiO, involves trivalent /bivalent nickel ions, with trivalent nickel ions produced during in-s itu lithiation of NiO in the carbonate melt.