Nanostructure Silicon Anodes Prepared by Chemical Reduction Method for Lithium Ion Batteries

Silicon is a promising anode material in high energy density application of lithium ion batteries because it is known to have the largest specific capacity (~4200mAh/g), ten time that of the commercially graphite carbon. However, they have shown great capacity fading and short battery life due to big volume changes upon insertion and extraction of lithium, which results in pulverization and loss of the electrical contact between the active material and the current collector. In this thesis, we successfully fabricated two kinds of nanostructured silicon anodes by chemical reduction method and test them versus Li as half-cell. Porous Si showed a reversible capacity of 1482mAh/g after 30 cycles, which is 50% of its initial capacity. Carbon coating greatly improves the cycling stability and increase the capacity retention to 85%. Compared Si nanosheets structure, graphene-silica sandwich structure showed great improvements in capacity and cycling stability. This chemical reduction method is facile, mass productive and thus is promising in the nanostructure silicon anode fabrication