Silicon-coated carbon nanofiber hierarchical nanostructures for improved lithium-ion battery anodes

Silicon-coated carbon nanofibers (CNFs) are a viable method of exploiting silicon's capacity in a battery anode while ameliorating the complications of silicon expansion as it alloys with lithium. Silicon-coated CNFs were fabricated through chemical vapor deposition and deposited onto a carbon fiber mesh. This novel anode material demonstrated a capacity of 954 mAh g−1 in the first cycle, but faded to 766 mAh g−1 after 20 cycles. Structural characterization of the samples before and after cycling was carried out using field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The results suggest that a portion of the fade may be due to separation of the silicon coating from the CNFs. Enough silicon remains in contact with the conductive network of CNFs to allow a usable reversible capacity that well exceeds that of graphite. An anode of this material can double the capacity of a lithium-ion battery or allow a 14% weight reduction.

► Developed silicon coated carbon nanofiber material for lithium ion batteries.
► Silicon is deposited upon a carbon fiber/carbon nanofiber network.
► CNF structure maintains contact with silicon despite silicon distortion during cycling.
► Material demonstrated 766 mA g−1 reversible capacity after 20 cycles.