Accession Number:

ADA621752

Title:

A High-Performance Lithium-Ion Battery Anode Based on the Core-Shell Heterostructure of Silicon-Coated Vertically Aligned Carbon Nanofibers

Descriptive Note:

Journal article

Corporate Author:

KANSAS UNIV CENTER FOR RESEARCH INC LAWRENCE

Report Date:

2013-01-01

Pagination or Media Count:

14.0

Abstract:

This study reports a high-performance hybrid lithium-ion anode material based on coaxially coated Si shell on vertically aligned carbon nanofiber VACNF core. The unique cup-stacking-like graphitic microstructure of the VACNFs provides abundant broken graphitic edges at the sidewall, making VACNFs an interesting Li intercalation medium and, more importantly, a robust and highly conductive core which can form good interface with the active Si shell for Li storage. Reversible Li intercalation and extraction with the capacity of 350-400 mAhg-1 has been obtained with bare VACNFs at C2 and C1 rates. Upon sputtering deposition of Si, it forms an interesting core-shell vertical nanowire structure with a tapered coaxial Si shell. The uniform vertical alignment enables Si to spread along the whole VACNF length, resulting in a much smaller shell thickness. With the 10 m long VACNF arrays, the core-shell nanowires remain well separated from each other even after depositing a thick layer of Si equivalent to 1.5 m nominal thickness on flat substrates. This open three-dimensional hybrid architecture allows the Si shell to freely expandcontract in the radial direction during Li2 insertionextraction. High-performance lithium storage with the specific capacity of 3000-3650 mAhg-1 normalized to the Si mass has been achieved, which changes little as the power rate is increased by 20 times from C10 to C0.5 or 2C. The obtained capacity matches the maximum reported value for amorphous Si, indicating that the Si shell is fully active due to effective charge collection by the VACNF core and short diffusion path for Li insertionextraction.

Subject Categories:

  • Energy Storage
  • Coatings, Colorants and Finishes

Distribution Statement:

APPROVED FOR PUBLIC RELEASE