Vanadium oxide films synthesized by CVD and used as positive electrodes in secondary lithium batteries

Vanadium oxide films were synthesized by chemical vapor deposition from pure or diluted VO(OC3H7)(3) precursor. An annealing process at 500 degreesC was required to obtain crystallized V2O5. X-ray diffraction patterns have pointed out the influence of the operating conditions for the vanadium oxide deposition on the crystallites sizes. No significant difference in the roughness factor was observed by atomic force microscopy measurements before and after annealing at 500degreesC. As-deposited V6O13 films were also directly obtained by changing the operating conditions. The insertion/deinsertion of Li+ into the host structure was investigated in 1 M LiClO4-propylene carbonate. V2O5 films exhibit low irreversible capacity and high cyclability even for a deep lithium insertion ratio; in addition, only small amounts of gamma-phases were formed during cycle life at low potential without significant effects on its electrochemical performance. After subsequent cycles between 3.8 and 2.2 V vs. Li/ Li+, the reversible capacity is found to be approximate to250 mAh g(-1) (y approximate to 1.65) close to the theoretical one. V6O13 films exhibit reversible capacity of about 410 mAh g(-1) ( y approximate to 7.9). (C) 2004 The Electrochemical Society.