Hierarchical architectured NiS@SiO2 nanoparticles enveloped in graphene sheets as anode material for lithium ion batteries

• NiS@SiO2/graphene is prepared by a simple electrostatic attraction route.
• NiS@SiO2/graphene presents nano-porous and hierarchical core-shell structure.
• Superior cyclic stability and excellent rate capability are achieved.

A well-designed hierarchical architecture NiS@SiO2/graphene is prepared through electrostatic self-assembly between (3-aminopropyl) triethoxysilane (APTES)-modified NiS and graphene in aqueous solutions at room temperature. The obtained composite possesses a unique structure with SiO2 ultrasmall nanoparticles (3–5 nm) derived from the pyrolysis of APTES homogeneously anchored on the surface of NiS nanoparticles (100 nm), forming NiS@SiO2 core-shell hybrid particles, which are well enveloped in graphene sheets. The SiO2 nanoparticles act as pillars to form open space between graphene sheets and NiS particles, which can buffer the volume change and afford easy electrolyte-wetting and fast lithium ion transport channels. The graphene sheets can not only significantly enhance the overall electrical conductivity of the NiS@SiO2/graphene electrode, but also serve as a blanket to wrap NiS particle and so as to avert its exfoliation from electrode due to large volume change during cycling. The prepared NiS@SiO2/graphene nanocomposite exhibits high reversible capacity (∼750 mAh g−1 for 100 cycles), remarkable cycling stability and impressive rate capability.