高振实密度圆饼状LiFePO_4/C的制备及电化学性能

Synthesis and Electrochemical Properties of Cake-like LiFePO_4/C with High Tap Density

以乙二醇为溶剂,采用溶剂热法一步合成圆饼状LiFePO_4,然后以葡萄糖为碳源与合成的LiFePO_4前躯体高温烧结得到碳包覆的LiFePO_4/C复合材料,其振实密度高达1.3 g·cm^(-3)。采用X射线衍射(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)对LiFePO_4/C复合材料进行了物相和形貌表征,研究结果表明制备得到的LiFePO_4呈圆饼状,且生成的圆饼是由单晶LiFePO_4纳米片堆积而成。此外,LiFePO_4颗粒表面碳层包覆均匀。将制备的LiFePO_4/C用作锂离子电池正极材料,电化学性能测试表明其具有高的充放电比容量(在0.1C时放电,其初始放电比容量为157.7 mAh·g^(-1))与良好的循环性能(500次循环后容量保持率为82.4%)。

The cake-like LiFePO4 is synthesized through a solvothermal method with ethylene glycol as the solvent. After that, the LiFePO4 precursor and glucose are mixed and calcined in an reduced atmosphere to obtain the LiFePO4/C composite with a high tap density of 1.3 gcm-3. The LiFePO4/C samples were characterized by X-ray diffraction, scanning and transmission electron microscopies, whose results demonstrate that the cake-like LiFePO4/C consists of single-crystalline LiFePO4 nanoplates. Additionally, an amorphous carbon layer is evenly coated on LiFePO4. The electrochemical properties of the cathode material LiFePO4/C indicate that it possess a high charge/discharge specific capacity （the initial discharge capacity reach to 157.7 mAhg-1 at 0.1C） and good cycle stability （82.4% of capacity retention at 1C after 500 cycles）.