Highly conducting fibrous carbon-coated silicon alloy anode for lithium ion batteries

Carbon-coated silicon/iron silicide nanocomposite anodes developed for lithium ion rechargeable batteries present a large initial irreversible capacity owing to many pores in the carbon coating layer generated from the carbonization of polyfurfuryl alcohol (PFA) resin during the heat treatment. To overcome this issue of large initial irreversible capacity loss, we attempted to fill the pores via chemical vapor deposition (CVD) of carbon using acetylene as the source. The Brunauer-Emmett-Teller surface area is reduced from 51 to 7 m2 g−1 and the initial irreversible capacity also decreased from 197 mA h g−1 corresponding to a simple resin-coated sample to 164 mA h g−1 after CVD of carbon on the resin-derived carbon coating. The rate capability tests show an excellent ability to maintain a capacity of 500 mA h g−1 at the rate of 7 C (10.5 A g−1), suggesting that the carbon nanofibers (CNFs) formed by the catalytic decomposition of acetylene on iron silicide grains aid in improving the electrical connection between the active anode particles during cycling.