In situ preparation of double-layered Si/SiOx nano-film as high performance anode material for lithium ion batteries

Abstract

In this work, plasma enhanced chemical vapor deposition is used as a method for preparation of double-layered Si/SiOx nano-film. The SiOx nano-layer with different thickness were successfully deposited on Si film with 170 nm. After several cycles of charge and discharge, the SiOx film is lithiated into lithium silicate that can provide excellent lithium ion channel. When the thickness of the oxide layer keeps at 20 nm, the Si-SiOx-20 maintains a dramatic capacity with 1773.8 mAh·g−1 at the rate of 10C (1C = 4200 mA g−1). In contrast, the capacity of pure Si-170nm is only 23.3 mAh·g−1 at same rate. Over than that, a reasonable oxide layer can quite effectively buffer the volume effect. The Si-SiOx-20 holds a capacity 941.2 mAh·g−1 higher than the Si-170nm with 549.2 mAh·g−1 after 200 cycles at the rate of 0.5C.