Effect of silver co-sputtering on amorphous V2O5 thin-films for microbatteries

The effect of silver co-sputtering on the microstructural and electrical properties of amorphous V2O5 films is investigated. The films are grown by dc reactive sputtering and are applicable to thin-film microbattery cathodes. Analysis with glancing-angle X-ray diffraction (GXRD), scanning electron microscopy (SEM), X-ray photon spectroscopy (XPS), and Fourier transformation infrared (FT-IR) spectroscopy confirm that the growing rate, silver content and microsturucture of the V2O5 films are dominantly affected by the r.f. power supplied on the silver metal targets. The discharge capacity and cycle ability of microbatteries increases with increasing silver content in the thin cathode films. In addition, it is found that silver co-sputtered V2O5 cathode films, if only obtained at not more than 30 W, exhibit better discharge capacity, cycle ability and lithium-ion diffusivity than an undoped V2O5 cathode film. This is due to increases both in the electronic conductivity with doping elements of high electronic conductivity and in the distance between two adjacent V2O5 layers by co-sputtered silver atoms.