Preparation and electrochemical performance of Si@cyclized-polyacrylonitrile/ multi-walled carbon nanotubes anode composites

Si/C electrode composites were prepared by simple high-energy ball milling and high-temperature pyrolysis. The polyacrylonitrile (PAN) coated nano Si particles (Si@PAN) were mixed with multi-walled carbon nanotubes (MWCNTs) to prepare Si@cyclized-PAN/MWCNTs(Si@c-PAN/MWCNTs) composites as the anode material for lithium ion battery. A thin layer of c-PAN was coated on Si nanoparticles to efficiently accommodate a large volume change of Si particles in cycles. The MWCNTs network functions as matrix for Si@c-PAN nano particles, which not only prevent the agglomeration of Si@c-PAN particles, but also improve the electrical conductivity of electrodes significantly. The electrochemical tests show that the first discharge specific capacity of the Si@c-PAN/MWCNTs composite electrode is 2 098 mA•h/g at the current density of 0.2 A/g and the initial coulomb efficiency is 86%. After 50 cycles, the reversible specific capacity of Si@c-PAN/MWCNTs composite electrode maintains at 1 278 mA•h/g. When the current rate reaches 2 A/g, the specific capacity of Si@c-PAN/MWCNTs composite electrode keeps at 600 mA•h/g, exhibiting good cycle stability.