疏松多孔CoFe2O4-还原石墨烯电极复合材料的制备与性能

采用原位溶剂热法，以氧化石墨烯（GO）与Co2+、Fe3+为原料制备疏松多孔的纳米CoFe₂O₄-还原氧化石墨烯（CoFe₂O₄-rGO）复合材料。采用XRD、Raman、SEM和HRTEM测试表征了纳米CoFe₂O₄-rGO复合材料的结构与形貌。测试结果表明，纳米CoFe₂O₄-rGO复合材料具有三维结构。自组装的多孔CoFe₂O₄纳米球粒径约为200 nm，在rGO上均匀分散，解决了CoFe₂O₄易团聚的问题。电化学测试结果表明，纳米CoFe₂O₄-rGO复合材料具有较高的比容量及优异的循环和倍率性能，在100 mA·g-1的电流密度下其比容量为1 262 mAh·g-1，50次循环后比容量仍能保持在642 mAh·g-1；并在2 000 mA·g-1的大电流密度下仍具有221 mAh·g-1的比容量。纳米CoFe₂O₄-rGO复合材料拥有更优异的电化学性能的原因在于CoFe₂O₄纳米球在rGO上均匀分布。三维结构增加了Li+储存的活性位点，有效缓解了电极的体积收缩/膨胀效应，提高了纳米CoFe₂O₄-rGO复合材料的导电性。 

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.