Electrochemical characteristics of lithium vanadate, Li1+xVO2, new anode materials for lithium ion batteries

Lithium vanadium oxide has been synthesized as an anode material for lithium ion batteries by spray pyrolysis technique. The precursor prepared by spray pyrolysis is sintered at 1000 degrees C under 10% H-2/Ar atmosphere. Highly crystallized hexagonal lithium vanadate, Li1 + x VO2, is obtained without any impurities. The product has mean particle size of 7-8 mu m. Lattice parameters of as-prepared powders vary largely according to Li/V ratio. The powder having the lowest c/a ratio shows the largest discharge capacity. Optimum x value is 0.2 in the view point of the discharge capacity (294 mAh g(-1)) and the cycle retention (>90%, after 25 cycles). Structural change of as-prepared lithium vanadate is investigated by ex situ X-ray diffraction analysis on charged electrodes at various state of charge (SOC). Lithium vanadate undergoes two step phase transition during charging process and its main peak gets broader as the charge state gets higher. This peak broadening is explained by the breaking down of particles at high SOC. (C) 2010 Elsevier B.V. All rights reserved.