Identification of the sodium diffusion mechanisms within the layered Na(Li) xMo 2O 4 system. Effect of water and exchange of sodium by lithium

Abstract

The layered molybdates of general formula M x Mo 2O 4 (M=Li or Na) were shown to be promising cathode materials for rechargeable batteries. One of the limitations for the performance of rechargeable batteries is the kinetics of the intercalation reactions taking place at the electrode/electrolyte interfaces. This paper reviews our results concerning the understanding of the diffusion mechanisms involved during the intercalation of Na, Li, and H 2O between the MoO 2 layers, which form these molybdenum oxides. Electrochemical techniques, as well as ac and dc measurements, were used to evaluate the electrical properties of these materials, which were found to be related to the changes observed in the local structure, and occuring during the intercalation reaction. Study of the local structure was carried out using NMR and ESR spectroscopies, while ac and dc techniques were used to evaluate the electrical parameters.