采用溶胶-凝胶法在人造石墨表面包覆不同有机物碳源后进行热处理,制备了具有＂核-壳＂结构的热解无定形碳包覆人造石墨改性负极材料。通过X射线衍射（XRD）、扫描电子显微镜（SEM）、恒电流充放电以及循环伏安（CV）测试等方法研究了碳源种类和包覆量对材料晶格结构、颗粒形貌及电化学性能的影响。结果表明,以聚偏氟乙烯（PVDF）作为碳源、5%（质量分数）的包覆量制备的材料具有较高的可逆比容量（约360mAh/g）和首次库仑效率（88.5%）,表现出优异的倍率性能和循环稳定性。这主要是由于5%（质量分数）的PVDF包覆量在石墨表面形成的无定形碳包覆层比较完整且厚度适宜,无定形碳的各向同性结构特征增加了锂离子扩散的通道,促进了电极反应过程的进行。
Organic pyrolytic carbon-coated artificial graphite anode material with a core-shell structure was prepared via a sol-gel and pyrolysis route. The effects of coating amounts and species of carbon resource on the lattice structure, the particle morphology and the electrochemical performance of the modified artificial graphite were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), constant current charge- discharge and cyclic voltammogram (CV) tests. The electrochemical measurements reveal that the sample coated with 5wt% PVDF exhibits a stable specific capacity of 360mAh/g, a higher initial coulombic efficiency of 88.5 %, excellent ratecapability and good cycling stability. This may be mainly attributed to the complete formation and the proper thickness of amorphous carbon film on the surface of graphite particles. The isotropic structure characteristics of amorphous carbon increase the diffusion channels of lithium ions and thus facilitate the electrode reaction process.
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