Porous nickel MCFC cathode coated by potentiostatically deposited cobalt oxide III.: Electrochemical behaviour in molten carbonate

A cobalt oxide coating was deposited on porous nickel by a potentiostatic electrochemical technique and studied in molten (Li0.52Na0.48)(2)CO3 eutectics at 650 degrees C under an atmosphere of CO2:Air (30:70). The structural and morphological characteristics of this coating before and after immersion in the molten electrolyte were described in a previous paper, showing that the initial CO3O4 layer is rapidly transformed into LiCoO2 and afterwards probably into LiCo1-yNiyO2. In the present part, the electrical and electrochemical behaviour of this promising novel MCFC cathode material was thoroughly analysed during 50 h by impedance spectroscopy. A porous nickel cathode was tested in the same conditions and taken as a reference. The oxidation and lithiation reactions are accelerated by the presence of cobalt. The charge transfer resistance is higher with the coated cathode but the diffusion resistance through this new material is lower in comparison with the state-of-the-art cathode. (C) 2007 Elsevier B.V. All rights reserved.