CoO纳米颗粒/石墨烯纳米纤维复合材料的制备及电化学性能

用石墨烯和Co(CH₃COO)₂·4H₂O作为原料,利用超声辅助法合成了锂离子电池的负极材料CoO纳米颗粒/中空石墨烯纳米纤维复合物.采用X射线衍射(XRD)确定材料的物相组成,采用扫描电子显微镜(SEM)和透射电子显微镜(TEM)观察材料的表面形貌和微观结构,采用X射线光电子能谱(XPS)确定材料的价态结构.采用循环伏安、恒电流充放电和交流阻抗谱表征材料的电化学性能.结果显示,在100 mA/g的电流密度下,循环了160次后,可逆容量仍超过800 mA/g,库仑效率保持在99%以上.该材料优异的电化学性能主要归因于石墨烯的中空纤维结构,中空内部可以容纳电解液,能直接将离子输送到颗粒表面,实现了离子的快速传输;二维中空纤维搭建成三维网络结构,实现了三维电子传导网络.

Preparation of CoO Nanoparticles/Hollow Graphene Nanofiber Composites and Its Electrochemical Performances

Using the graphenes and Co（CH₃COO）₂·4H₂O as raw materials， the CoO nanoparticles/hollow graphene nanofiber composites were synthesized by the ultrasound-assisted method as the anode materials for lithium-ion batteries. X-ray diffraction（XRD） was used to determine the phase compositions of the materials， scanning electron microscope（SEM） and transmitting electron microscope（TEM） were used to observe the surface morphologies and microstructures of the materials， and X-ray photoelectron spectroscopy（XPS） was used to determine the valence structures of the materials. Cyclic voltammetry， galvanostatic charge and discharge， and AC impedance spectroscopy tests were performed on the materials to characterize its electrochemical performances. The electrochemical performances of the composite materials showed that the reversible capacity still exceeded 800 mA/g and the coulombic efficiency was above 99% at a current density of 100 mA/g after 160 cycles. The excellent electrochemical performances were attributed to the hollow fiber structures of graphenes. The prepared materials exhibited two very excellent characteristics： one was that the hollow interior could contain electrolytes， which would directly transport ions to the particle surfaces， realizing rapid ion transmission； second， the two-dimensional hollow fibers were built into a three-dimensional network structures to realize a three-dimensional electronic conduction network.