Nanocolumnar-Architectured, Layered Cu/Si Film as Anodes for Rechargeable LIB

Abstract

In this work, we produce layered Cu/Si film by deposition a thin Cu film on Si nanocolums by an oblique angle deposition method. Galvanostatic half-cell measurements show that, the Cu coated Si nanocolumn arrays performs 1700 mAh g-1 in the first cycle, then after 10 cycles its performance is stabilized to 500 mAh g-1 with 99% coulombic efficiency for 90 cycles. This high performance is related to its particular morphology and physical properties. First, having homogenously distributed nano-sized porosities in the Cu coated film increases the mechanical tolerance of the electrode against the volumetric changes occurred during galvanostatic test. Second, the ductile behavior of the Cu film holds the electrode together to prevent the electronic isolation, pulverization or delamination of the coating. Third, Cu15Si4 intermetallics increase the mechanical resistances of the coating against the stress generated in the electrode. Last, the surface reactivity of the electrode, hence its interaction with the electrolyte, is also changedbecause of the Cu layer presence as interlayer, leading to higher coulombic efficiency once a stable SEI forms on the anode.