Preparation and properties of loose porous CoFe₂O₄-reduced graphene electrode composites

Loose and porous nano CoFe₂O₄-reduced graphene oxide (CoFe₂O₄-rGO) composites were prepared via in situ solvothermal method, using graphene oxide (GO), Co²⁺ and Fe³⁺ as the raw materials. XRD, Raman, SEM and HRTEM were employed to characterize the structure and morphology of nano CoFe₂O₄-rGO composites. The results show that nano CoFe₂O₄-rGO composites exhibit 3D structure. The self-assembled porous nanospheres with a diameter of about 200 nm are uniformly dispersed on rGO, which solves the agglomeration of CoFe₂O₄. The electrochemical test results show that nano CoFe₂O₄-rGO composites deliver a comparatively high specific capacity and excellent cycle and rate performance. The specific capacity reaches 1 262 mAh·g^-1 at a current density of 100 mA·g^-1, which can still maintain at 642 mAh·g^-1 after 50 cycles. The specific capacity reaches 221 mAh·g^-1 at a high current density of 2 000 mA·g^-1. The enhanced electrochemical performance of nano CoFe₂O₄-rGO composites results from the homogenous distribution of CoFe₂O₄ nanospheres on rGO. The 3D structure provides more active sites of Li⁺ storage, and thus effectively relieve the volume shrinkage/expansion of the electrodes, which in return improve the conductivity of nano CoFe₂O₄-rGO composites.