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化学学报
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化学学报 ›› 2009, Vol. 67 ›› Issue (21): 2413-2420. 上一篇    下一篇

研究论文

S-M(M=Cu, Co, Ti)复合掺杂层状LiMnO2 的合成及其电化学性能

粟 智*,a   叶世海b   王永龙b   

  1. (a新疆师范大学生命科学与化学学院 乌鲁木齐 830054) (b南开大学化学学院 新能源材料化学研究所 天津 300071)
  • 投稿日期:2009-01-20 修回日期:2009-04-16 发布日期:2009-06-25
  • 通讯作者: 粟智 E-mail:suzhixj@sina.com
  • 基金资助:

    国家自然科学基金资助项目(No. 20773070)和新疆师范大学博士博士后基金资助项目（XJNUBS0807）

Synthesis and Electrochemical Properties of S-M (M＝Cu, Co, Ti) Co-doped Layered LiMnO2 Cathode Materials

Su, Zhi*,a   Ye, Shihaib    Wang, Yonglongb   

  1. (a College of Life and Chemistry Science, Xinjiang Normal University, Urumqi 830054) (b Institute of New Energy Material of Chemistry, Nankai University, Tianjin 300071)
  • Received:2009-01-20 Revised:2009-04-16 Published:2009-06-25

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用水热法合成了锂离子电池正极材料正交结构LiMnO2材料, 并对其进行S2－、大尺寸阳离子(Cu2＋, Co3＋, Ti4＋)以及硫-金属离子复合掺杂改性. 用X射线衍射(XRD)、X光电子能谱分析(XPS)、透射电子显微镜(TEM)、恒电流充放电、交流阻抗谱(EIS)等测试技术进行表征. 实验结果表明: 当掺入离子的含量较低时, 得到的产物能保持完整的正交结构, 并表现出较好的电化学性能. S2－和非Jahn-Teller效应大尺寸阳离子的掺入使材料的循环稳定性能大幅度提高, 而这种提高是源于这些离子对LiMnO2结构的稳定作用. 电极材料Li1.02Mn0.988Ti0.012O1.989S0.011显示了最优的电化学性能, 在50 mA•g－1放电速率下, 其初始放电容量为142.6 mAh•g－1, 60次循环后放电容量为213.4 mAh•g－1. 硫-金属阳离子复合掺杂, 综合了大尺寸阳离子可以提高材料中Li＋的扩散能力和S2－掺杂抑制Jahn-Teller畸变两方面优势, 使层状结构LiMnO2正极材料既保持了较高的容量又获得良好的循环性能.

关键词: 水热合成, 正交结构, 正极材料, 复合掺杂

Orthorhombic structure LiMnO2 compounds used as cathode materials for lithium-ion batteries were synthesized by a hydrothermal method, and modified by doping with sulphur ion (S2－), large-sized cation (Cu2＋, Co3＋, Ti4＋) and co-doping with S-M (M＝Cu, Co, Ti). The structure and electrochemical performances of the as-prepared materials were studied by X-ray powder diffraction (XRD), X-ray photoelectron microscopy (XPS), transmission electron microscopy (TEM), chronoamperometry and electrochemical impedance spectroscopy (EIS). The synthesized materials exhibit a standard orthorhombic structure and good electrochemical performance after the doping with a spot of above-mentioned ions. The beneficial effect of these cations on improving cyclability was demonstrated, due to that the stability of LiMnO2 orthorhombic structure is enhanced by the doping with these non-Jahn-Teller ions. The electrode of Li1.02Mn0.988Ti0.012O1.989S0.011 shows excellent electrochemical properties with the first discharge capacity of 142.6 mAh•g－1 and retaining 213.4 mAh•g－1 after 60 cycles at a current rate 50 mA•g－1. The electrochemical results reveal that the co-doping of S-M (M＝Cu, Co, Ti) combines the advantages of the improvement of Li＋diffusion by cation doping, with the suppression of Jahn-Teller distortion by S2－ doping. In the meantime, the co-doped materials also achieve higher capacity and better cyclic performance than the pristine LiMnO2.

Key words: hydrothermal synthesis, orthorhombic structure, cathode material, co-doping

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