Silicon nanoparticles coated with nanoporous carbon as a promising anode material for lithium ion batteries

As a promising anode candidate, silicon (Si) nanoparticles have been widely studied for lithium ion batteries. However, Si nanoparticles suffer from volume expansion during lithiation/delithiation, which leads to irreversible capacity decrease. In this work, perlite is utilized to prepare Si nanoparticles by magnesiothermic reduction. To alleviate the volume expansion of Si nanoparticles, a nanoporous carbon is prepared to coat Si nanoparticles using chitosan (C) as a carbon source and zinc chloride (Z) as a pore former. TEM micrographs show that the porous carbon with mesoporous size has formed and coated on the surface of Si nanoparticles. The prepared carbon coating Si sample (Z-C@Si-5 present 5 times the mass ratio of Z to C) exhibits suitable pore volume (0.576 cm3g-1) and pore size (4-6 nm), as well as excellent specific surface area (418.315 m2g-1) The obtained Z-C@Si-5 also shows promising electrochemical performance with a reversible capacity of 2064.11 mAh g-1 at 0.2 C and 847.32 mAh g-1 at 4 C, as well as a high capacity retention. The promising electrochemical performance originated from the nanoporous carbon coating, which not only effectively alleviated the volume expansion of Si, but also provided the rapid transport channel of lithium ions in its nanoporous structure.