THIN-FILM VANADIUM-OXIDE ELECTRODES FOR LITHIUM BATTERIES

Vanadium pentoxide films prepared by three techniques have been used as electrodes in solid-state batteries. The three types of films behave differently as host materials for lithium insertion. The electrochemical properties of sputtered films are very dependent on the oxygen partial pressure in the sputter gas, as is the sputter rate. The best electrochemical properties are obtained with a high oxygen partial pressure, whereas it is necessary to use lower oxygen pressures to reach acceptable sputter rates. Vanadium oxide films prepared by physical vapour deposition apparently forms compact layers that break under cycling. These films have a relatively low capacity for lithium insertion and the transport kinetics are slow. This material is not suited for electrode material. Vanadium oxide xerogels appear to be good alternatives to the sputtered films, although the capacity for lithium insertion is lower. The properties of these films can be varied by heat treatment, and good cycling performance has been demonstrated.