物理化学学报 >> 2011, Vol. 27 >> Issue (10): 2340-2346.doi: 10.3866/PKU.WHXB20111002

电化学和新能源 上一篇    下一篇

镧掺杂的二氧化锰/碳纳米管电化学超级电容器复合电极

薛荣, 阎景旺, 田颖, 衣宝廉   

  1. 中国科学院大连化学物理研究所, 辽宁大连 116023
  • 收稿日期:2011-02-24 修回日期:2011-07-13 发布日期:2011-09-27
  • 通讯作者: 阎景旺 E-mail:yanjw@dicp.ac.cn
  • 基金资助:

    中国科学院大连化学物理研究所重要方向性项目"电动汽车用超级电容器储能系统的研究与开发"资助

Lanthanum Doped Manganese Dioxide/Carbon Nanotube Composite Electrodes for Electrochemical Supercapacitors

XUE Rong, YAN Jing-Wang, TIAN Ying, YI Bao-Lian   

  1. Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning Province, P. R. China
  • Received:2011-02-24 Revised:2011-07-13 Published:2011-09-27
  • Contact: YAN Jing-Wang E-mail:yanjw@dicp.ac.cn
  • Supported by:

    The project was supported by the Important Directional Project of‘the Research and Exploration of Supercapacitor Storage System for Electric Vehicle’from Dalian Institute of Chemical Physics, Chinese Academy of Sciences, China.

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摘要： 尽管在二氧化锰/多壁碳纳米管(MnO2/MWCNTs)上获得了较高的比电容, 低电导率仍是制约MnO2担载量或膜厚度提高的主要障碍. 另一个问题是MnO2/MWCNTs 的循环稳定性远低于活性炭. 所以截止到目前这一新型材料的应用仍然受到很大的限制. 本文采用原位还原的方法制备镧掺杂二氧化锰/多壁碳纳米管电化学超级电容器复合电极材料. 分别通过透射电镜(TEM)、扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱等技术对这些复合材料的形貌与结构进行了分析. 采用循环伏安法、恒电流充放电法和交流阻抗法对其进行了电化学性能的研究. 研究结果表明, 通过还原MnO4- 可以在MWCNTs 上形成La 掺杂MnO2复合材料. La 掺杂降低了复合电极的电阻, 这是因为La 的引入可以增大MnO2的晶格缺陷, 从而提高材料的电导率以及电极的电化学性能. 因此La 掺杂是克服MnO2本征导电性差的有效途径之一. 掺杂La 可以在不增大电极电阻的情况下提高MnO2的担载量或膜厚度. La 掺杂的更重要的作用是使以MnO2/MWCNTs 作电极的对称电化学超级电容器的循环性能得到显著改善. 此外, La掺杂也使复合电极的比电容得到一定程度的提高.

关键词: 超级电容器, 多壁碳纳米管, 镧, 二氧化锰, 赝电容

Abstract: Although higher specific capacitances have been achieved for manganese dioxide/multi-walled carbon nanotubes (MnO2/MWCNTs), the low conductivity of MnO2 is still the main obstacle in increasing its loading or film thickness. Another problem is that the cycling stability of MnO2/MWCNTs is much lower than that of activated carbon electrodes. Therefore, this new type of electrode material is still limited in application until now. In this paper, lanthanum doped MnO2/MWCNTs composites were prepared by an in situ redox method. The surface morphology and phase structure of the as-prepared samples were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectrometry. The electrochemical properties were investigated by cyclic voltammetry (CV), galvanostatic charge/discharge, and electrochemical impedance spectroscopy (EIS). The La-doped MnO2 could be formed on the MWCNTs by the reduction of MnO4-. The resistance of the composite electrodes decreased because La doping increases the number of imperfections in the MnO2 lattice, which improves the electrical conductivity and the electrochemical activity of the electrode. La doping is, therefore, an effective way to overcome the intrinsic low electric conductivity of MnO2, which facilitates an increase in the loading or the film thickness of MnO2 without increasing electrode resistance. The major effect of La doping is a significant improvement in the charge/discharge cycling performance of a symmetric electrochemical supercapacitor with electrodes composed of MnO2/ MWCNTs. The specific capacitance of the composite electrodes was improved by La doping.

Key words: Supercapacitor, Multi-walled carbon nanotube, Lanthanum, Manganese dioxide, Pseudocapacitance