Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (10): 2633-2637.doi: 10.3866/PKU.WHXB20101015

• ELECTROCHEMISTRY • Previous Articles     Next Articles

Effect of Hydrazine on the Performance of LiNi0.5Mn1.5O4Cathode Materials

CHANG Zhao-Rong, DAI Dong-Mei, LI Bao, TANG Hong-Wei   

  1. College of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007, Henan Province, P. R. China
  • Received:2010-02-12 Revised:2010-07-15 Published:2010-09-27
  • Contact: CHANG Zhao-Rong E-mail:czr_56@163.com
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21071046) and Henan Key Scientific and Technological Project, China (080102270013).

Abstract:

Reduction pretreatment of the precursor of LiNi0.5Mn1.5O4 was carried out by adding hydrazine to a solution of NaOH during precursor synthesis. Accordingly, the effect of hydrazine on the performance of LiNi0.5Mn1.5O4 was studied by comparing the electrochemical properties of this sample with those of pristine samples (LiNi0.5Mn1.5O4 without hydrazine pretreatment). We synthesized LiNi0.5Mn1.5O4 by co-precipitation using a two-step drying method with NiSO4 and MnSO4 as raw materials. The results of electrochemical experiments show that the LiNi0.5Mn1.5O4 from the hydrazine pretreated precursor has a much higher special capacity than the pristine sample at the same charge/ discharge current density. Moreover, the former shows much better electrochemical performance at a high discharge current density. Results of powder X-ray diffraction (XRD) reveal that the LiNi0.5Mn1.5O4 from the hydrazine pretreated precursor shows a pure spinel phase (no impurity phase detected) while the pristine sample containsa minor impurity phase. Results of scanning electron microscopy (SEM) show that the crystal impurities have a layered structure and are mixed with octahedral crystals of LiNi0.5Mn1.5O4. We show that the impurity in the precursor is insoluble Na0.55Mn2O4·1.5H2O, which derives from the oxidation of Mn(OH)2 by O2 and a final transformation into Na0.7MnO2.05.

 

Key words: Cathode material, LiNi0.5Mn1.5O4, Lithium ion battery, Coprecipitation method, Reductiontreatment

MSC2000: 

  • O646