Sputtering Deposition of Aluminium Molybdenum Alloy Thin Film Anodes for Thin Film Microbatteries

Al5Mo thin film anodes for Li-ion batteries were prepared using DC sputtering under different conditions, the latter being specified as deposition at room temperature (SO), deposition at 300 degrees C (Si), and deposition at room temperature followed by thermal annealing at 300 degrees C (S2). The thin films were deposited using an aluminum target tiled with molybdenum discs at a ratio calculated based on the theoretical sputtering yields. The structural and compositional analyses performed with x-ray diffraction (XRD) and energy-dispersive x-ray spectroscopy (EDX) confirmed the Al5Mo compound formation and the Al/Mo elemental ratio, respectively. The compound formation was observed to be evident only for the thin films subjected to heat treatment during or after deposition. Scanning electron micrographs reveal a higher porosity of approximately 23% for sample SO and a lower porosity of around 18% for sample Si. The chronopotentiometry results show a higher volumetric specific capacity of approximately 197 mAh/cm(3) for sample Si. Capacity increments have been observed for all samples upon charge-discharge cycles, whose values after 25 cycles for samples SO, Si, and S2 were 41.2%, 20.4%, and 21.1%, respectively.