Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (9): 2287-2292.doi: 10.3866/PKU.WHXB201605164

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Surface Analysis of the Lithium-Rich Cathode Material Li1.2Mn0.54Co0.13Ni0.13NaxO2 by Advanced Electron Microscopy

Wei HUANG,Chun-Yang WU,Yue-Wu ZENG,Chuan-Hong JIN*(),Ze ZHANG   

  • Received:2016-04-05 Published:2016-09-08
  • Contact: Chuan-Hong JIN
  • Supported by:
    the National Natural Science Foundation of China(51222202)


In this work, Li1.2Mn0.54Co0.13Ni0.13NaxO2 was prepared via an ion-exchange process combined with a solid-state reaction. Aberration-corrected scanning transmission electron microscopy (STEM), energydispersive X-ray spectroscopy (EDS), and electron energy loss spectroscopy (EELS) were all used to study the surface structure and chemical distribution of the resulting material. Nickel (Ni) was found to be enriched at the surface in regions perpendicular to the lithium diffusion channels (that is, the (200) surfaces) and also exhibited a tendency to diffuse into the lithium (Li) layers, generating a Fm3m rocksalt phase. In contrast, cobalt (Co) segregated along the transition metal (TM) layers of the (001) and (200) surfaces. The results of aging trials demonstrated that Co-enriched layers lead to surface structure instability, as evidenced by the formation of a large number of antisite defects (Li-TM) and rocksalt phase structures at the (001) surface during aging.

Key words: Lithium ion battery, Cathode material, Lithium rich cathode material, Surface segregation, Scanning transmission electron microscopy