Molten carbonate fuel cells: contribution to the study of cathode behaviour and oxygen reduction in molten Li2CO3---K2CO3 at 650°C

A contribution to the understanding of the complex behaviour of the cathode in molten carbonate fuel cells, focussing on the oxygen reduction mechanism and the lithiation process, is presented in this paper. As a first step, the thermodynamic stability ranges of oxygen and nickel species are established. The electrochemical behaviour of superoxide and oxide species, unstable in the carbonate melt but locally created in the diffusion layer, is investigated according to the acidity conditions. Nickel recovered in situ by nickel oxide is analysed by X-ray diffraction and voltammetric techniques. The lithiation and dissolution of nickel oxide are more particularly described.