Nitrogen-doped graphene enwrapped silicon nanoparticles with nitrogen-doped carbon shell: a novel nanocomposite for lithium-ion batteries

A novel nanocomposite (NG/Si@NC) consisting of nitrogen-doped graphene (NG) enwrapped Si nanoparticles (SiNPs) with a nitrogen-doped carbon shell (NC) was prepared as a new anode material for lithium-ion batteries (LIBs). The NG/Si@NC was synthesized by a facile and environmentally friendly solution-mixing and carbonization approach. SEM and TEM confirmed that NC-encircled SiNPs (Si@NC) were evenly anchored on and completely enwrapped by NG. It was found that nitrogen was simultaneously doped into graphene nanosheets and carbon shell on SiNPs. Electrochemical measurements demonstrated the significant role of nitrogen doping in enhancing the electrochemical performance of NG/Si@NC. The NG/Si@NC electrode exhibited a reversible capacity of 938 mAh g−1 at a current density of 500 mA g−1 over 100 cycles, which is significantly higher as compared to the nondoped graphene enwrapped SiNPs with a nondoped carbon shell (G/Si@C) (603 mAh g−1) and graphene enwrapped bare SiNPs (G/Si) (240 mAh g−1).