碳包覆碳酸钴锂离子电池负极材料的制备及电化学性能

Preparation and Electrochemical Properties of Carbon-Coated CoCO_3 as an Anode Material for Lithium Ion Batteries

以葡萄糖作为碳源,通过简单的水热反应获得菱形碳包覆碳酸钴(Co CO3/C)复合材料,并研究了其作为锂离子电池负极材料的电化学性能.晶型和表面形貌通过X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)进行表征,用热重-差热分析法(TG-DTA)来测试Co CO3/C材料中碳的含量,用拉曼光谱分析无定型碳的存在.Barrett-Joyner-Halenda(BJH)则用来分析材料的孔径分布情况.实验表明,碳包覆不仅在Co CO3颗粒表面包覆了一层无定性碳,使得Co CO3材料在充放电过程中保持结构的稳定性,也形成了一些大约30 nm左右的介孔,这种孔的存在有助于电解液中离子的传输,从而提高材料的电化学性能.电极材料在0.90C(1.00C=450 m A g–1)倍率下进行循环测试,500次后的容量仍保持在539 m Ah g–1,显示出了较好的循环性能.当增加到3.00C倍率时Co CO3/C容量为130 m Ah g–1,再恢复到0.15C倍率时容量依然能够达到770m Ah g–1,表现出了Co CO3/C具有良好的稳定性.

Diamond-shaped carbon-coated CoCO3（CoCO3/C） particles were prepared by a simple hydrothermal method, and carbon coating was realized using glucose as the carbon source. This study focuses on the electrochemical performance of CoCO3/C as an anode material. Its surface morphology and crystal lattice structure were characterized by X-ray diffraction（XRD）, scanning electron microscopy（SEM）,and transmission electron microscopy（TEM）. The content and structure of the carbon coating layer were further investigated by the thermogravimetry-differential thermal analysis（TG-DTA） technique and Raman spectroscopy. The pore size distribution was characterized using the Barrett-Joyner-Halenda（BJH） method.The results show that the carbon coating process creates not only a layer of amorphous carbon on the surface of CoCO3, but also a porous structure with pore size of ～30 nm. The amorphous carbon layer enhances the structural stability during the charging and discharging process, and the porous structure facilitates the movement of ions in the electrolyte, and thus improves its electrochemical performance. When the cycling performance was tested for 500 cycles, this CoCO3/C material maintained a capacity of 539 mAh·g^-1 at 0.90C（1.00 C = 450 mA· g^-1）, showing its excellent cycling capacity. When the current rate was increased to 3.00 C,the capacity was 130 mAh·g^-1. When the current rate was returned to 0.15 C, its capacity was 770 mAh·g^-1,demonstrating the great rate performance and stability of CoCO3/C.