欢迎访问《电化学(中英文)》期刊官方网站,今天是

电化学(中英文) ›› 2013, Vol. 19 ›› Issue (2): 155-163.  doi: 10.61558/2993-074X.2108

• 研究论文 • 上一篇    下一篇

CuF2/MoO3/C复合正极的电化学阻抗谱研究

史月丽,吴楠,沈明芳,董佳群,庄全超*,江利   

  1. 中国矿业大学材料科学与工程学院锂离子电池实验室,江苏 徐州 221116
  • 收稿日期:2012-07-16 修回日期:2012-08-30 出版日期:2013-04-28 发布日期:2012-09-10
  • 通讯作者: 庄全超 E-mail:zqc209@126.com
  • 基金资助:

    2012年中国矿业大学高水平论文专项基金(No. 2012LWB13)资助

An Electrochemical Impedance Spectroscopic Study of CuF2/MoO3/C Cathode Composites

SHI Yue-li, WU Nan, SHEN Ming-fang, DONG Jia-qun, ZHUANG Quang-chao*, JIANG Li   

  1. School of Materials Science and Engineering, China University of Mining & Technology, Xuzhou 221166, Jiangsu, China
  • Received:2012-07-16 Revised:2012-08-30 Published:2013-04-28 Online:2012-09-10
  • Contact: ZHUANG Quang-chao E-mail:zqc209@126.com

摘要: 采用球磨方法制备了CuF2/MoO3/C复合材料电极,利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、恒流充放电、循环伏安(CV)和电化学阻抗谱(EIS)等方法表征与观察复合材料的结构与形貌,测试了电极的电化学性能. 结果表明,球磨CuF2和MoO3晶粒的尺寸为200 ~ 300 nm. CuF2/MoO3/C复合电极10 mA?g-1电流密度首次放电容量为647 mAh.g-1,但随之复合材料循环寿命迅速衰减.循环伏安曲线首次放电,2.2 V左右出现了一个还原峰,第2、3周期该还原峰电位升至3.2 V左右. CuF2/MoO3/C复合电极的Nyquist图由高、中频区两个半圆串接和一条斜线组成. 放电过程,高频区半圆相应于锂离子扩散多层SEI膜,还与电极材料与集流体的接触有关. 中频区半圆与CuF2和MoO3及C的肖特基接触有关. 低频区斜线反映扩散传递过程. CuF2/MoO3/C电极电荷传递阻力较大,这可能也是CuF2/MoO3/C电极容量较快衰减的原因.

关键词: CuF2/MoO3/C复合材料, 转化反应, 电化学阻抗谱, 肖特基接触阻抗

Abstract: Composite electrode of CuF2/MoO3/C was fabricated through high energy mechanical milling. The properties of CuF2/MoO3/C were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (TEM), galvanostatic charge-discharge measurements, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the grain sizes of CuF2 and MoO3 after milling were 200 ~ 300 nm, and the initial discharge capacity of CuF2/MoO3/C was 647 mAh?g-1 at room temperature and at a current density of 10 mA.g-1. However, the capacity decayed rapidly in the next cycles. CV curves showed one reduction peak at 2.2 V in the first cycle and another one at 3.2 V in the following cycles. The Nyquist diagram of CuF2/MoO3/C electrode consisted of two semicircles and one line. During the discharge process, the high frequency semicircle (HFS) may be associated with not only the Li+ migration through the SEI film, but also contact resistance between the CuF2/MoO3/C composites and the current collector. The middle frequency semicircle (MFS) should be related to the Schottky contact between CuF2 and conductive agents, which may be the important feature of such composites materials with big band gap. Besides the low frequency line may be related to the diffusion step. A very large value of charge transfer resistance for the CuF2/MoO3/C electrode may induce the rapid decay in capacity.

Key words: CuF2/MoO3/C composite electrode, conversion reactions, electrochemical impedance spectra, Schottky contact impedance

中图分类号: