Acta Phys. -Chim. Sin. ›› 2011, Vol. 27 ›› Issue (02): 437-442.doi: 10.3866/PKU.WHXB20110239

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Effect of Calcination Atmosphere on Li/Ni Disorder and Electrochemical Performance of Layered LiNi0.5Mn0.5O2

WANG Xiao-Ya, CHENG Qian, HUANG Tao, YU Ai-Shui   

  1. Department of Chemistry, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Institute of New Energy, Fudan University, Shanghai 200438, P. R. China
  • Received:2010-10-23 Revised:2010-12-14 Published:2011-01-25
  • Contact: Yu Ai-Shui E-mail:asyu@fudan.edu.cn
  • Supported by:

    The project was supported by the National Key Basic Research Program of China (973) (2009CB220100), National High Technology Research and Development Program of China (863) (2009AA033701), and Science & Technology Commission of Shanghai Municipality, China (08DZ2270500).

Abstract:

Layered LiNi0.5Mn0.5O2 was synthesized by a solid state reaction method under air or oxygen atmosphere. The obtained materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), electrochemical impedance spectroscopy (EIS), and charge-discharge tests. The results show that the LiNi0.5Mn0.5O2 synthesized by the solid state reaction method under both air and oxygen atmospheres give a pure phase and good crystallinity, however, their electrochemical performance differs. The material synthesized under oxygen gives better electrochemical performance including a higher first discharge capacity and better cycle stability. At a rate of 0.1C the first discharge capacity of the material synthesized under oxygen was found to be 178 mAh·g-1. After 50 charge and discharge cycles the discharge capacity was still 165 mAh·g-1 giving a capacity retention rate of 92.7%. For the material synthesized under air, the first discharge capacity at a rate of 0.1C was found to be 164 mAh·g-1. After 50 charge and discharge cycles, the discharge capacity was 137 mAh·g-1 giving a capacity retention rate of 83.5%. The reason for the material synthesized under oxygen having better electrochemical performance than the material synthesized under air is due to the oxygen atmosphere suppressing the Li/Ni exchange ratio in LiNi0.5Mn0.5O2.

Key words: Lithium ion battery, Cathode material, LiNi0.5Mn0.5O2, Li/Ni exchange, Calcination atmosphere

MSC2000: 

  • O646