High performance three-dimensional Ge/cyclized-polyacrylonitrile thin film anodes prepared by RF magnetron sputtering for lithium ion batteries.

Here, germanium (Ge) nanofilm as the high-capacity electrode was deposited on the three-dimensional porous nickel foam substrate by radio frequency sputtering. Then, cyclized-polyacrylonitrile (PAN) was coated on the surface of Ge nanofilm to get the excellent rate capability and cycle stability owing to the poor cycle life of the as-prepared Ge nanofilm. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy were employed to analyze the microstructure and morphology of the Ge/cyclized-PAN electrodes. The Ge/cyclized-PAN manifests excellent electrochemical performance with high specific capacity and good cycling stability due to the unique structural features. At the charge-discharge rate of 0.1, 0.2, 0.5, 1, 2, and 5 C over a voltage window of 0.01-1.0 V, the discharge capacities of the composite are 731, 722, 701, 676, 621, and 566 mAh g, respectively. The specific capacity retention is up to 98 % with less capacity fading after 100 cycles at 1 C. [ABSTRACT FROM AUTHOR]