物理化学学报 >> 2016, Vol. 32 >> Issue (9): 2287-2292.doi: 10.3866/PKU.WHXB201605164

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富锂正极材料Li1.2Mn0.54Co0.13Ni0.13NaxO2表面结构的电子显微分析

黄威,邬春阳,曾跃武,金传洪*(),张泽   

  • 收稿日期:2016-04-05 发布日期:2016-09-08
  • 通讯作者: 金传洪 E-mail:chhjin@zju.edu.cn
  • 基金资助:
    国家自然科学基金资助项目(51222202)

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 E-mail:chhjin@zju.edu.cn
  • Supported by:
    the National Natural Science Foundation of China(51222202)

摘要:

采用离子交换加固相烧结法制备出富锂锰基正极材料Li1.2Mn0.54Co0.13Ni0.13NaxO2,利用球差校正扫描透射电子显微镜(STEM)、X射线能谱(EDS)、电子能量损失谱(EELS)等分析手段对材料表面结构与成分展开表征。结果表明:镍(Ni)在样品表面存在选择性富集(垂直于锂扩散通道的表面,如(200)面),倾向扩散进入锂离子层,并导致表面出现层状结构到岩盐相(rocksalt, Fm3m)结构转变;而钴(Co)在所观察的(001)、(200)表面均存在不同程度的富集,且集中在过渡金属层。进一步研究发现,表面钴(Co)富集不利于层状结构的稳定,时效后样品的(001)面观察到明显的表面重构,存在数量较多的过渡金属(TM)-锂(Li)反位缺陷与岩盐相结构区域。

关键词: 锂离子电池, 正极材料, 富锂正极材料, 表面富集, 扫描透射电子显微镜

Abstract:

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

MSC2000: 

  • O646