Characterization of sputtered vanadium oxide films for lithium batteries

Orthorhombic V 2O 5 crystal thin films have been prepared by radio frequency sputter deposition in an argon atmosphere containing 20% oxygen and a V 2O 5 target. The film can undergo reversible charge–discharge cycling. The mass change that takes place during charge–discharge cycling is in good agreement with the lithium value from measurement of the resonance frequency changes of a quartz crystal microbalance. However, during the first few cycles, the amount of mass change differs a little from the lithium value, which may be caused by creation of a surface film on V 2O 5. During subsequent cycling, the electrode mass continues to increase which that means some part of the inserted lithium can not be extracted. This mass accumulation is clearly related to the origins of the reduced charging capacity of the V 2O 5 films for cathode material of lithium batteries.