Journal of Inorganic Materials ›› 2018, Vol. 33 ›› Issue (9): 993-1000.doi: 10.15541/jim20170579

• Orginal Article • Previous Articles     Next Articles

Tuning Electrochemical Performance through Non-stoichiometric Compositions in High-voltage Spinel Cathode Materials

Sai-Xi LEE1,2(), Xue-Yin WANG2, Qing-Wen GU2, Yong-Gao XIA2, Zhao-Ping LIU2(), Jie HE1()   

  1. 1. School of Chemical Engineering, Anhui University of Science and Technology, Huainan 232001, China
    2. Ningbo Institute of Materials Technology & Engineering, Chinese Academy of Sciences, Ningbo 315201, China;
  • Received:2017-12-04 Revised:2018-03-31 Online:2018-09-20 Published:2018-08-14
  • About author:LEE Sai-Xi. E-mail: saixi@nimte.ac.cn

Abstract:

In this study, a simple method to prepare high-voltage spinel cathode materials though controlling stoichiometric ratio in their compositions was reported. Non-stoichiometric and stoichiometric high-voltage spinel LiNi0.5Mn1.5O4 cathode materials were prepared by solid-state reaction between Li2CO3 and Ni0.25Mn0.75(OH)2 prcursor. Their morphologies, structures and electrochemical performance were characterized by scanning electron microscopy, X-ray diffraction, neutron diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, as well as electrochemical curves. The second particles occupied the similar sizes ~8 μm, which were composed of nanoparticles. Compared to stoichiometric LiNi0.5Mn1.5O4, Ni/Mn cations in non-stoichiometric LiNi0.5Mn1.5O4 sample distributed randomly, resulting in structure disorder demonstrated by the analysis of X-ray diffraction, neutron diffration and Raman spectroscopy. Less Mn3+ content in stoichiometric LiNi0.5Mn1.5O4 sample was detected though X-ray photoelectron spectroscopy. It is believed that more Mn3+ content and Ni/Mn cation disorder would benefit rate cpability and cycling performance. As a result, non-stoichiometric LiNi0.5Mn1.5O4 sample delivers superior dicharge capacity at higher rates, even though it shows relatively minor discharge capacity at low rates. What’s more, higher capacity retention for the non-stoichiometric LiNi0.5Mn1.5O4 sample was found, which was promoted to 91.2% at 1.0C rate after 400 cycles. At the same time, in situ X-ray diffraction measurements revealed that single-step phase transformation for non-stoichiometric LiNi0.5Mn1.5O4 sample significantly enhanced structural stability during the electrochemical process. Spinel LiNi0.5Mn1.5O4 with non-stoichiometric composition provides a promising solution for their potential application in high-energy-density lithium-ion batteries.

Key words: high voltage, spinel-structured, cathode materials, non-stoichiometric, cycling stability

CLC Number: 

  • TQ174