Improving Electrochemical Performance of CuSi Thin Film by Depositing Cu Thin Film via Magnetron Sputtering

Abstract

In the present work, we deposited a bare and a (10 nm thick) Cu capped SiCu films (that contains 10 %at. Cu) by magnetron sputtering. The results showed that the top coating does not only exert remarkable favorable effects on the capacity, but also improves the capacity retention and coulombic efficiency. The galvanostatic test results showed that with C/12 rate, Cu capped SiCu film delivered 750 mAh/g after 40th cycles, and it retained stable up to 100 cycle with 98% coulombic efficiency, whilst the bare SiCu film performed a gradual decrease in capacity. We believe that during cycling, the top Cu film being ductile, form a network to prevent the electronic isolation of Si particles, or delamination. Cu atoms buffered the mechanical stress generated in the electrode following the volumetric changes. Furthermore, the surface reactivity of the SiCu electrode, hence its interaction with the electrolyte, was also changed leading to a longer cycle life electrode.