Decoration of graphene with silicon nanoparticles by covalent immobilization for use as anodes in high stability lithium ion batteries

Si nanoparticle-graphene hybrids are fabricated by covalent immobilization and subsequent heating in a H₂ + Ar atmosphere. The absence of a graphite (002) peak in X-ray diffraction shows that the hybrid synthesized by this approach prevents graphene nanosheets re-agglomerating. Transmission electron microscopy shows a homogeneous distribution of Si nanoparticles on the graphene. Galvanostatic charge/discharge tests demonstrate that the Si nanoparticle-graphene hybrid has much better charge capacity retention than pristine Si nanoparticles and a Si nanoparticle/graphene mixture. The relationship of the capacity to the weight ratio of Si nanoparticles and graphene in the hybrid has been investigated. The results reveal that the hybrid of with a weight ratio 15:1 (Si:G) exhibits the most stable cycle performance, which retains 92.7% capacity of the 1st cycle after 50 charge/discharge cycles. The 1st Li⁺ insertion capacity is 1297 mAh g^-1, and the 50th Li⁺ insertion capacity is 1203 mAh g^-1.