Highly Conductive 90V2O5·10P2O5 Nanocrystalline Cathode Materials for Lithium-ion Batteries

The aim of this research was to optimize process of nanocrystallization of vanadate-phosphate glasses in order to reach as high electronic conductivity as possible. 90 V2O5·10P2O5 glasses were prepared by a standard melt-quenching technique under different synthesis conditions. The glass transition temperature, the crystallization temperature and the electric conductivity at RT is evidently correlated with the synthesis temperature. The samples were annealed at different temperatures. As a result of this optimization, a sample with σ(25 °C) = 0.7·10-1 S/cm was synthesized. The microstructure of the sample consists of V2O5 nanocrystallites with size within 15÷30 nm. The significant increase in the conductivity is discussed in terms of the Mott's model of electron hopping and a core-shell concept. The electrochemical measurements have shown that up to 3 moles of Li+ ions can be inserted into 1 mole of V2O5.