MOLTEN-CARBONATE FUEL-CELLS - CONTRIBUTION TO THE STUDY OF CATHODE BEHAVIOR AND OXYGEN REDUCTION IN MOLTEN LI2CO3-K2CO3 AT 650-DEGREES-C

A contribution to the understanding of the complex behaviour of the ca thode in molten carbonate fuel cells, focussing on the oxygen reductio n 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 condi tions. Nickel recovered in situ by nickel oxide is analysed by X-ray d iffraction and voltammetric techniques. The lithiation and dissolution of nickel oxide are more particularly described.