Highly Stable Vanadium Oxide Cathodes Prepared by Plasma-Enhanced Chemical Vapor Deposition

Vanadium oxide films have been prepared by plasma-enhanced chemical vapor deposition for rechargeable lithium-battery applications. Vanadium oxytrichloride (VOCl₃) was employed as the vanadium precursor. Various parameters, such as the partial pressures of carrier gas and reactant gases, substrate temperature, and radio-frequency power, have been optimized to improve the electrochemical properties of the films. The film deposition rate was ∼11 Å/s. The best films obtained in this work displayed an oxygen-to-vanadium atomic ratio close to that of V₆O₁₃. These films exhibited a high discharge capacity and were very stable during electrochemical cycling. The discharge capacity of these films exceeded 408 mAh/g (or 1265 mAh/cm³) when tested between 4.0 and 1.5 V, and the energy density of these films (∼5000 Å thick) was 960.3 Wh/kg. The films exhibited negligible capacity fade from the second cycle to more than 5800 cycles when cycled between 4.0 and 1.8 V with a current density of 114 μA/cm². The combination of high capacity, extended cycling stability, and rapid deposition rate make both this material and its deposition technology very attractive choices for the manufacturers of rechargeable lithium batteries.