Nuclear Techniques ›› 2019, Vol. 42 ›› Issue (11): 110102-110102.doi: 10.11889/j.0253-3219.2019.hjs.42.110102

• SYNCHROTRON RADIATION TECHNOLOGY AND APPLICATIONS • Previous Articles     Next Articles

Study on the mechanism of the influence of component proportion on the structure and electrochemical performance of Li(NixCoyMn1-x-y)O2 cathode materials

Yanru WU1,2,Nian ZHANG1,Hui ZHANG1,Na LIU3,Zhongling XU3,Qifeng LI3,Yujun CHEN3,Xiaosong LIU1,4()   

  1. 1. State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
    3. Contemporary Amperex Technology Limited, Ningde 352000, China
    4. School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China
  • Received:2017-10-15 Revised:2018-04-06 Online:2019-11-10 Published:2019-11-18
  • Contact: Xiaosong LIU E-mail:xliu3@mail.sim.ac.cn
  • About author:WU Yanru, female, born in 1992, graduated from University of Chinese Academy of Sciences with a master's degree in 2018, focusing on cathode materials for Li-ion batteries
  • Supported by:
    National Nature Science Foundation of China(21473235)

Abstract: Background

Li(NixCoyMn1-x-y)O2 (NCM), as a new cathode material of Li-ion battery, has been successfully used in the electric vehicles. It has the advantages of high energy density, good cycling stability and low cost. The crystal structure and electronic structure of Li(NixCoyMn1-x-y)O2 (NCM) cathode are mainly affected by the variable composition of 3d transition metals Ni, Co and Mn.

Purpose

This study aims to investigate the influence of component proportion on the structure and electrochemical performance of Li(NixCoyMn1-x-y)O2 cathode materials.

Methods

First of all, Li(Ni0.6Co0.2Mn0.2)O2 (NCM622), Li(Ni0.5Co0.2Mn0.3)O2 (NCM523) and Li(Ni0.33Co0.33Mn0.33)O2 (NCM333), were selected as three common cathode materials used in industry. Their structures and electrochemical performances were studied by electrochemical methods, scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XAS). Then the corresponding relationship between structure and electrochemistry was established to optimize electrochemical performance of Li-ion batterie, and apply NCM materials to cathode of Li-ion batteries.

Results

Electrochemical measurement results show that NCM materials with higher nickel content have higher capacity density but lower rate capability. In SEM and XRD characterizations, the NCM materials with the three different compositions show similar morphology and crystal structure. XAS at Ni L-edge results reveal that by increasing nickel content in the NCM materials, the oxidation of Ni increases to a higher +3 state. In the O K-edge XAS, the enhanced intensity of a lower energy peak suggests the increased hybridization of Ni3d-O2p.

Conclusions

Based on the investigations of capacity and rate capability, NCM523 is found to be a well-balanced component. The evolution of Ni and O electron structure is a crucial factor in determining their electrochemical performance.

Key words: Li(NixCoyMn1-x-y)O2, Cathode material, Electronic structure, X-ray absorption spectroscopy