Acta Phys. -Chim. Sin. ›› 2016, Vol. 32 ›› Issue (6): 1489-1494.doi: 10.3866/PKU.WHXB2016032802

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Electron Microscopy Study of Surface Reconstruction and Its Evolution in P2-Type Na0.66Mn0.675Ni0.1625Co0.1625O2 for Sodium-Ion Batteries

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

  • Received:2016-03-17 Published:2016-06-03
  • Contact: Chuan-Hong JIN
  • Supported by:
    The project was supported by the National Natural Science Foundation of China(51222202)


We performed an aberration-corrected scanning transmission electron microscopy(STEM)andenergy-dispersive X-ray spectroscopy(EDS)study of Na0.66Mn0.675Ni0.1625Co0.1625O2,which was prepared via a solidstatereaction for sodium-ion battery applications.Powder X-ray diffraction(XRD)showed that the material hada well-crystallized P2-type layered structure(P63/mmc).Results from further STEM and EDS analyses showedthe presence of reconstructed surface layers of thickness about 1-2 nm,which contained a large amount ofantisite defects and obvious lattice distortions.Detailed chemical analysis showed an inhomogeneous elementaldistribution inside these reconstructed surface layers;they were cobalt rich and nickel deficient.These surfacelayers further evolved into thicker regions of width 5-10 nm,accompanied by a spinel(Fd3m)phase to rocksaltphase(Fm3m)transition.

Key words: Sodium ion battery, P2-type layer-structured cathode material, Surface reconstruction, Scanning transmission electron microscopy


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