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

A facile method is developed to in situ one-step synthesize CoFe ₂O₄/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 CoFe₂O ₄ 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 CoFe ₂O₄ 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).