Chem. J. Chinese Universities ›› 2010, Vol. 31 ›› Issue (2): 247.

• Articles • Previous Articles     Next Articles

Synthesis and Electrochemical Properties of Monoclinic Layered Structure LiMn0.97Al0.03O2-x(PO4)x Materials

SU Zhi1*, XU Mao-Wen1, YE Shi-Hai2, WANG Yong-Long2   

  1. 1. College of Life and Chemistry Science, Xinjiang Normal University, Urumqi 830054, China;
    2. Institute of New Energy Material of Chemistry, Chemistry College, Nankai University, Tianjin 300071, China
  • Received:2009-03-02 Online:2010-02-10 Published:2010-02-10
  • Contact: SU Zhi. E-mail: suzhixj@sina.com
  • Supported by:

    国家自然科学基金(批准号: 20773070)和新疆高校科研计划重点项目(批准号: XJEDu2009I28)资助.

Abstract:

Layered lithium manganese bronze LiMn0.97Al0.03O2, LiMnO1.99(PO4)0.01 and LiMn0.97Al0.03O2-x·(PO4)x(x=0.01, 0.03, 0.05) with a monoclinic structure were synthesized by the two-step high temperature solid state reaction and a hydrothermal ion exchange method, using Na2CO3, (CH3COO)2Mn·2H2O, Na3PO4·12H2O and Al2O3 as the starting materials. XRD and SEM were used to characterize the structures and morphology of the precursors and products by the ion exchange reaction. The effect of the doping ions on the structure and the electrochemical performances of the samples was investigated by X-ray photoelectron spectroscopy(XPS), Fourier transform infrared spectroscopy(FTIR), electrochemical impedance spectroscopy(EIS) and chronoamperometry techniques. The results showed the co-doping of Al-PO4 combined the advantages of the improvement of the electrochemical reactivity and the decrease of the electrode reaction resistance by the Al3+ doping, as well as enlarging the unit-cell volume by the PO43- doping. It benefits for the Li+ diffusion in the cathode and the suppression of Jahn-Teller distortion. Comparing the pristine one, the Al-PO4-co-doped LiMnO2 cathode exhibits higher discharge capacity and better cyclic stability.

Key words: Monoclinic LiMnO2; Cathode material; Co-doping; Hydrothermal ion-exchange; Electrochemical property

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