Anode-shielded, sputter-deposited nanocrystalline Sn thin-film anodes for lithium-ion batteries

Sn thin-film anodes have been prepared using radio frequency driven magnetron sputtering. With appropriate anode shielding on the sputter gun during deposition, film crystallinity and surface morphology can be well controlled. The anode shielding changed the plasma ion density, resulting in lower ion flux available on the substrate. Sn thin-film anodes deposited with anode shielding can develop fine and smooth morphology composed of ultrasmall particles (5-10 nm) uniformly dispersed on the surface. Grazing-angle X-ray diffraction and field-emission scanning electron microscopy were used to characterize the film crystallinity and surface morphology. The electrochemical properties of the thin-film anodes deposited under various conditions were measured and compared. High reversible capacity with low first-cycle capacity loss can be obtained. During the first 15-20 cycles significant capacity loss was observed, but at the next cycles capacity became more stable. The cycling properties of the Sn thin-film anodes were improved significantly. (c) 2006 The Electrochemical Society.