物理化学学报 >> 2011, Vol. 27 >> Issue (06): 1439-1445.doi: 10.3866/PKU.WHXB20110607

电化学和新能源 上一篇    下一篇

表面活性剂碳化法合成Fe3O4/C复合物及其电化学性能

程凤, 黄可龙, 刘素琴, 房雪松, 张新   

  1. 中南大学化学化工学院, 长沙 410083
  • 收稿日期:2011-03-14 修回日期:2011-03-30 发布日期:2011-05-31
  • 通讯作者: 黄可龙 E-mail:klhuang@mail.csu.edu.cn
  • 基金资助:

    国家自然科学基金(50972165)资助项目

Surfactant Carbonization to Synthesize a Fe3O4/C Composite and Its Electrochemical Performance

CHENG Feng, HUANG Ke-Long, LIU Su-Qin, FANG Xue-Song, ZHANG Xin   

  1. College of Chemistry & Chemical Engineering, Central South University, Changsha 410083, P. R. China
  • Received:2011-03-14 Revised:2011-03-30 Published:2011-05-31
  • Contact: HUANG Ke-Long E-mail:klhuang@mail.csu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (50972165).

摘要:

以水热法合成的包覆油酸的α-Fe2O3粒子为前驱体, 在氩气下500 °C煅烧1 h, 得到Fe3O4/C纳米复合物. 用傅里叶变换红外(FTIR)光谱, X射线衍射(XRD), 扫描电镜(SEM), X射线能量散射(EDX)谱, 高分辨透射电镜(HRTEM), 元素分析, 循环伏安(CV)和恒流充放电测试等方法对材料的结构、形貌、成分及电化学性能进行了表征. 结果表明: 所制备的Fe3O4/C复合物呈长约200 nm, 粗约100 nm的纺锤形, 表面碳层厚约1-2 nm, 碳含量为1.956%(质量分数); 这种复合物作为锂离子电池负极材料具有很好的循环稳定性(在0.2C (1C=928 mA·g-1)循环80次后具有691.7 mAh·g-1比容量)和倍率性能(在2C循环20次后依然有520 mAh·g-1比容量). 相对于未包覆的商业Fe3O4粒子, 复合物显著提高的电化学性能是由于碳包覆能防止粒子聚集, 提高导电性以及稳定固体电解质界面(SEI)膜.

关键词: 锂离子电池, 四氧化三铁, 表面活性剂碳化, 原位碳包覆, 复合物

Abstract:

Oleic acid-capped α-Fe2O3 nanoparticles were initially prepared as precursors by a simple hydrothermal method. Fe3O4/C nanocomposites were synthesized by annealing the precursor at 500 °C for 1 h under an Ar atmosphere. The surface organic groups and core phase structure of the samples were characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD), respectively. Scanning electron microscopy (SEM) was used to observe their morphology. The existence of carbon was confirmed by elemental analysis, energy-dispersive X-ray (EDX) spectroscopy and high-resolution transmission electron microscopy (HRTEM). Cyclic voltammetry (CV) and galvanostatic discharge/charge measurements were used to evaluate the electrochemical performance of the as-prepared Fe3O4/C nanocomposites. The results showed that Fe3O4/C nanocomposites were spindles alike with a length of about 200 nm and a diameter of about 100 nm. A carbon layer of 1-2 nm in thickness was coated on the surface of the Fe3O4 nanocrystals and the carbon content was 1.956% (mass fraction). As anode materials for lithium-ion batteries, the composite exhibited excellent cycling performance (691.7 mAh·g-1 after 80 cycles at 0.2C (1C=928 mA·g-1)) and rate capability (520 mAh·g-1 after 20 cycles at 2C). Compared with commercial Fe3O4 particles, the remarkably improved electrochemical performance of the Fe3O4/C composites was attributed to in situ carbon coating, which prevented nanoparticle aggregation, increased electronic conductivity and stabilized the solid electrolyte interface (SEI) films.

Key words: Lithium-ion battery, Magnetite, Surfactant carbonization, In situ carbon coating, Composite

MSC2000: 

  • O646