High Performance Lithium-ion Battery Electrode: Silicon Coated on Vertically Aligned Carbon Nanofibers

This study reports a high-performance hybrid lithium-ion anode material using coaxially coated silicon shells on vertically aligned carbon nanofiber (VACNF) cores. The robust bush-like highly conductive VACNFs effectively connect high-capacity silicon shells for lithium-ion storage. Such architecture allows the Si shells to freely expand/contract in the radial direction during lithium-ion insertion/extraction. A high specific capacity of 3000-3650 mAh(gSi)-1 was obtained at C/1 rate, comparable to the maximum value of amorphous Si, and ∼89% of the capacity was retained after 100 charge-discharge cycles. The lithium-ion storage capacity remains nearly the same from C/10 to C/0.5 rates. The ability to obtain high capacity at significantly improved power rates while maintaining the extraordinary cycle stability demonstrates the utilization of the unique properties of such hybrid architecture for lithium-ion batteries.