Ultrathin Silicon Nanowires Produced by a Bi-Metal-Assisted Chemical Etching Method for Highly Stable Lithium-Ion Battery Anodes

Abstract

Silicon is widely studied as a high-capacity lithium-ion battery anode. However, the pulverization of silicon caused by a large volume expansion during lithiation impedes it from being used as a next generation anode for lithium-ion batteries. To overcome this drawback, we synthesized ultrathin silicon nanowires. These nanowires are 1D silicon nanostructures fabricated by a new bi-metal-assisted chemical etching process. We compared the lithium-ion battery properties of silicon nanowires with different average diameters of 100[Formula: see text]nm, 30[Formula: see text]nm and 10[Formula: see text]nm and found that the 30[Formula: see text]nm ultrathin silicon nanowire anode has the most stable properties for use in lithium-ion batteries. The above anode demonstrates a discharge capacity of 1066.0[Formula: see text]mAh/g at a current density of 300[Formula: see text]mA/g when based on the mass of active materials; furthermore, the ultrathin silicon nanowire with average diameter of 30[Formula: see text]nm anode retains 87.5% of its capacity after the 50th cycle, which is the best among the three silicon nanowire anodes. The 30[Formula: see text]nm ultrathin silicon nanowire anode has a more proper average diameter and more efficient content of SiOx. The above prevents the 30[Formula: see text]nm ultrathin silicon nanowires from pulverization and broken during cycling, and helps the 30[Formula: see text]nm ultrathin silicon nanowires anode to have a stable SEI layer, which contributes to its high stability.