Free-standing silicon nanorods on copper foil as anode for lithium-ion batteries

Abstract

A Si thick film with a thickness of ca. 2 μm was deposited on a copper substrate by electron cyclotron resonance–chemical vapor deposition (ECR–CVD) under a mixture of silane (SiH 4) and argon (Ar) gases. The surface modification of the silicon anode was carried out by the metal-assisted chemical etching method. Observation by SEM showed that the silicon on the copper substrate had a nanorod structure as the result of the etching process. The electrochemical performance of the anode prepared using the free-standing Si nanorods showed a specific capacity of more than 2000 mAh/g with 84% of the discharge capacity remaining ever after 25 cycles of charge and discharge, as compared with 35% of the discharge capacity remaining for the pristine Si thick film.