In situ one-step synthesis of CoFe2O4/graphene nanocomposites as high-performance anode for lithium-ion batteries

• The CFO/GN nanocomposites were synthesized by a facile one-step method.
• The CFO/GN electrode exhibits a high reversible capacity up to 937.73 mAh g−1 at high current densities of 1000 mA g−1.
• Graphene can effectively buffers the volumetric expansion of CFO during the charge/discharge process.

A facile method is developed to in situ one-step synthesize CoFe2O4/graphene (CFO/GN) nanocomposites as a promising high-performance anode for lithium-ion batteries. This method involves two processes occurring simultaneously: Co2+ and Fe2+ ions co-precipitate homogeneously on the surface of graphene oxides by using urea as the precipitant, while in situ reduction process reduces graphene oxides at the same time. As a consequence, the nanocomposites of CFO/GN self-assembled into a three-dimensional (3D) network architecture, in which CoFe2O4 nanoparticles with the diameter of 50-80 nm uniformly dispersed on graphene sheets. The as-synthesized CFO/GN nanocomposites exhibit a high specific reversible capacity up to 937.73 mAh g−1 with high charge/discharge reversibility at high current densities of 1000 mA g−1. In addition, it shows superior rate capability and good capacity retention of 69.5% after 50 cycles. The improved cyclic stability can be attributed to the synergistic interaction between uniformly dispersed CoFe2O4 nanoparticles and graphene, which offers the fast diffusion of Li ions (diffusion coefficient: 1.29 × 10−13 cm2 s−1) and low internal resistance (equivalent series resistance: 138.49 Ω cm−2).

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