金属有机框架衍生的高性能锂离子电池负极Co3O4/C复合材料

为克服Co_3O_4负极材料导电率低、循环稳定性差的缺点,选择Co_2(NDC)_2DMF_2(NDC=1,4-萘二甲酸根)为前驱体采用两步煅烧工艺,制备了具有高碳含量的Co_3O_4/C复合材料。采用X射线衍射(XRD)、扫描电子显微镜(SEM)、X射线光电子能谱(XPS)和拉曼光谱对样品进行了表征。采用热重分析法(TGA)测定了Co_3O_4/C中非晶态碳的含量。作为锂离子电池的负极材料,Co_3O_4/C具有高的可逆比容量、优异的循环性能(在200 m A·g~(-1)的电流密度下,循环200圈后放电比容量稳定保持在1 000 mAh·g~(-1))和良好的倍率性能(在100、200、500、1 000和2 000 mA·g~(-1)的电流密度下,放电比容量为分别1 076.3、976.2、872.9、783.6和670.1 mAh·g~(-1))。材料优异的电化学性能归结为有机配体衍生的高含量非晶态碳的导电和缓冲作用有利于电子的快速传递并有效减缓了金属氧化物充放电过程中的体积膨胀。

Metal-Organic Framework Derived Co3O4/C Composite as High-Performance Anode Material for Lithium-Ion Batteries

In order to overcome the disadvantages of the low electrical conductivity and poor cycling stability of Co₃O₄ anode material, a Co₃O₄/C composite was obtained by the judicious selection of Co₂(NDC)₂DMF₂ (NDC=1,4-naphthalene dicarboxylate) as precursor through a two-step calcination process. The sample was characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The content of amorphous carbon in Co₃O₄/C was tested by thermogravimetric analysis (TGA). As anode material for lithium-ion batteries (LIBs), Co₃O₄/C material showed a high reversible specific capacity, remarkable cycling performance (the specific discharge capacity was stable at 1 000 mAh·g^-1 under the current density of 200 mA·g^-1 even after 200 cycles) and an excellent rate performance with high average discharge specific capacities of 1 076.3, 976.2, 872.9, 783.6 and 670.1 mAh·g^-1 at 100, 200, 500, 1 000 and 2 000 mA·g^-1, respectively. The excellent electrochemical performance was attributed to the amorphous carbon derived from the organic ligand, which served as conductive path for easy electric charge transfer and buffer layer to slow down the volumetric stresses.