Co3O4/CNTs复合电极材料的水热法合成及电化学性能

为了考察CNTs使Co₃O₄/CNTs导电性和Co₃O₄分散性的提高对增大复合电极材料比电容的影响，以Co(NO₃)₂·6H₂O和CNTs为原料，通过水热法成功制备了Co₃O₄和Co₃O₄/CNTs复合电极材料，并采用TEM和XRD表征了复合材料的粒径大小、微观形貌和物相结构等物性，测试了Co₃O₄和Co₃O₄/CNTs的循环伏安(CV)、恒电流充放电(GCD)和电化学阻抗(EIS)等电化学性能。结果表明：由于CNTs的分散作用，复合材料中Co₃O₄的粒径从87 nm减小到13 nm，且具有尖晶石结构的Co₃O₄纳米粒子主要负载在CNTs的外表面；Co₃O₄/CNTs 复合材料的比电容和电容保持率均远高于Co₃O₄，且其导电性能提高对比电容增加的贡献远高于Co₃O₄粒径减小的贡献；经过2000次充放电循环后，Co₃O₄/CNTs复合材料的比电容保持在180 F/g左右，表现出良好的倍率性能和循环稳定性。

Hydrothermal Synthesisof the Co3O4/CNTs Composite Electrode and ItsElectrochemical Performance

To investigate the effects of enhancing the conductivity of Co₃O₄/CNTs and the dispersion of Co₃O₄ by CNTs on increasing the specific capacitance of composite electrode material, Co₃O₄ (87 nm), Co₃O₄ (14 nm) and Co₃O₄ (13 nm)/CNTs composite were prepared by the hydrothermal method using Co(NO₃)₂·6H₂O and CNTs as the raw materials. The microstructure, particle size, morphology and phase structure were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The results show that the size of Co₃O₄ nanoparticles in Co₃O₄ (13 nm)/CNTs composite is decreased from 87 nm to 13 nm due to the dispersion of CNTs. Co₃O₄ nanoparticles with spinel structure are mainly supported on the outer surface of CNTs. Electrochemical performances of pure Co₃O₄ and Co₃O₄/CNTs composite were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. It is found that the specific capacitance of Co₃O₄ (13 nm)/CNTs is 174.1 F/g at a current density of 0.5 A/g, and the capacitance retention rate of the composite maintains 89.3% when the current density is increased to 10 A/g. Both the specific capacitance and the capacitance retention rate of Co₃O₄ (13 nm)/CNTs are much higher than those of pure Co₃O₄. Moreover, the conductivity of the composite shows much more importance on the specific capacitance than the particle size. After 2000 cycles of charge and discharge, the specific capacitance of Co₃O₄ (13 nm)/CNTs composite remains at about 180 F/g, exhibiting excellent rate capacity and cycling stability.