The oxidation behavior of Ni-50%Co alloy electrode in molten Li+K carbonate eutectic

The oxidation behavior of Ni-50%Co alloy has been investigated in Li + K ca rbonate melt by electrochemical impedance spectroscopy and cyclic voltammet ry. Equivalent circuits have been worked out by simulating the impedance da ta, and the results are used to explain the oxidation kinetics. In the over all process of oxidation, the slowest step is the diffusion of metal ions t hrough the metal oxide layer. Lithiation reaction is observed at the second potential plateau region as judged from the values of the resistance eleme nt of the oxide layer determined from impedance measurement. From the cycli c voltammetry the peak corresponding to this reaction is also observed. In a Ni-50%/Co, the diffusion of Li+ ion from the carbonate melt into the oxid e layer causes further oxidation of Coo into LiCoO2. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.