Hierarchical flower-like carbon nanosheet assembly with embedded hollow NiCo₂O₄ nanoparticles for high- performance lithium ion batteries

Highlights: • Flower-like NiCo₂O₄@carbon nanosphere is firstly synthesized for Li-ion batteries. • The nanostructure exhibits the unique feature of hollow NiCo₂O₄ nanoparticles embedded inside and graphitized carbon layers coating outside. • The sample reveals stable structure, large specific surface area and good electrical conductivity. • The composite exhibits superior rate capability, cycling capacity and excellent Coulombic efficiency. - Abstract: The fabrication of closely bounded metal oxides/carbon hybrid nano-structures is significant for its use in energy-related areas especially lithium ion batteries (LIBs). In this research, a flower-like carbon sphere with hollow NiCo₂O₄ nanoparticles encapsulated inside the carbon thin nanopetal is fabricated by using a mixed basic carbonate nickel and cobalt sphere as the precursor and templates followed by the outer carbon membrane covering and two-step calcination process. When tested as anode material for LIBs, this flower-like carbon-based hybrid sphere demonstrates a significantly enhanced reversible capacity and cycling stability at various current densities.