Synthesis, structural and electrochemical properties of VO cathode for lithium batteries.

Single-phase three-dimensional vanadium oxide (VO) was synthesized by reduction of VO using a gas stream of ammonia/argon (NH/Ar). The as-synthesized oxide, prepared by this simple gas reduction method was subsequently electrochemically transformed into a disordered rock salt type-"Li3.7V4O9" phase while cycling over the voltage window 3.5 to 1.8 V versus Li. The Li-deficient phase delivers an initial reversible capacity of ∼260 mAhg at an average voltage of 2.5 V vs. Li/Li. Further cycling to 50 cycles yields a steady 225 mAhg. X-ray diffraction studies confirmed that (de) intercalation phenomena follows a solid-solution electrochemical reaction mechanism. As demonstrated, the reversibility and capacity utilization of this VO is found to be superior to battery grade, micron-sized VO cathodes in lithium cells.