Evaluation of Si/Ge multi-layered negative film electrodes using magnetron sputtering for rechargeable lithium ion batteries

The capacity of a silicon anode diminishes during repeated lithium ion intercalation and extraction as the volume changes cause the active material to internally crack. In this study, electrodes are prepared by a deposition method, and silicon and germanium are deposited on the copper current collector in sequence. The number of layers is varied and we find evidence that a multi-layered structure is capable of improving cyclic ability. It is expected that germanium would act as a buffer against the volume change of the silicon and contribute to the elevating lithium ion diffusion. The morphologic changes and cyclic performances of the multi-layered electrodes prepared by the deposition method are observed. Deposited electrodes are verified by X-ray diffractometry, Raman spectroscopy, field-emission scanning electron microscopy and transmission electron microscopy. Si-Ge bonding at the interface is analyzed using extended X-ray absorption fine structure. (C) 2010 Elsevier B.V. All rights reserved.