摘要
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CoFe_2O_4-还原氧化石墨烯(CoFe_2O_4-rGO)复合材料。采用XRD、Raman、SEM和HRTEM测试表征了纳米CoFe_2O_4-rGO复合材料的结构与形貌。测试结果表明,纳米CoFe_2O_4-rGO复合材料具有三维结构。自组装的多孔CoFe_2O_4纳米球粒径约为200nm,在rGO上均匀分散,解决了CoFe_2O_4易团聚的问题。电化学测试结果表明,纳米CoFe_2O_4-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100mA·g-1的电流密度下其比容量为1 262mAh·g-1,50次循环后比容量仍能保持在642mAh·g-1;并在2 000mA·g-1的大电流密度下仍具有221mAh·g-1的比容量。纳米CoFe_2O_4-rGO复合材料拥有更优异的电化学性能的原因在于CoFe_2O_4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CoFe_2O_4-rGO复合材料的导电性。
Loose and porous nano CoFe_2O_4-reduced graphene oxide(CoFe_2O_4-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 CoFe_2O_4-rGO composites.The results show that nano CoFe_2O_4-rGO composites exhibit 3 Dstructure.The self-assembled porous nanospheres with a diameter of about 200 nm are uniformly dispersed on rGO,which solves the agglomeration of CoFe_2O_4.The electrochemical test results show that nano CoFe_2O_4-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 of100 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 CoFe_2O_4-rGO composites results from the homogenous distribution of CoFe_2O_4 nanospheres on rGO.The 3 Dstructure 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 CoFe_2O_4-rGO composites.
引文
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