Acta Phys. -Chim. Sin. ›› 2014, Vol. 30 ›› Issue (12): 2283-2290.doi: 10.3866/PKU.WHXB201410132

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Preparation and Characterization of M(Ⅱ) and M(Ⅳ) Iso-Molar Co-Doped LiMn1.9Mg0.05Ti0.05O4 Cathode Materials for Lithium-Ion Batteries

WU Yue, LIU Xing-Quan, ZHANG Zheng, ZHAO Hong-Yuan   

  1. State Key Laboratory of Electronic Thin Film and Integrated Devices, School of Microelectronics and Solid State Electronics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
  • Received:2014-07-09 Revised:2014-10-13 Published:2014-11-27
  • Contact: LIU Xing-Quan E-mail:lxquan@uestc.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21071026) and Outstanding Talents Introduction Project of University of Electronic Science and Technology of China (08JC00303).

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Abstract:

An Mg(Ⅱ) and Ti(Ⅳ), iso-molar, co-doped cathode material LiMn1.9Mg0.05Ti0.05O4 for lithium-ion batteries was successfully synthesized via a sol-gel method, using lithium hydroxide, manganese acetate, magnesium nitrate, and butyl titanate as raw materials, and citric acid as a chelating agent. The as-prepared materials were characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical tests (including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) measurements). The results demonstrated that the cathode material LiMn1.9Mg0.05Ti0.05O4, which was obtained after calcination at 780℃ for 12 h, exhibited a fine microstructure and good electrochemical performance. When cycled at 4.35-3.30 V at room temperature, LiMn1.9Mg0.05Ti0.05O4 delivered a discharge specific capacity of 126.8 mAh·g-1 at 0.5C rate, and maintained a capacity of 118.5 mAh·g-1 after 50 cycles; the capacity retention of this material reached 93.5%. This material showed a discharge-specific capacity of 111.9 mAh·g-1 at 0.5C rate after 30 cycles, when it was cycled at 55℃; under these conditions the capacity retention reached 91.9%, far superior to the capacity retention of undoped LiMn2O4. The iso-molar co-doping of LiMn2O4 with Mg(Ⅱ) and Ti(Ⅳ) ions led to significant modification of the electronic and ionic conductivity, and increased the rate properties and electrochemical performance of the spinel lithium manganate at elevated temperatures.

Key words: Lithium ion battery, Cathode material, Spinel lithium manganate, Sol-gel method, Mg, Ti co-doping