Analytical electron microscopy of Li1.2Co0.4Mn 0.4O2 for lithium-ion batteries

J. G. Wen; J. Bareño; C. H. Lei; S. H. Kang; M. Balasubramanian; I. Petrov; D. P. Abraham

doi:10.1016/j.ssi.2010.11.030

Analytical electron microscopy of Li_1.2Co_0.4Mn _0.4O₂ for lithium-ion batteries

J. G. Wen
, J. Bareño
, C. H. Lei
, S. H. Kang
, M. Balasubramanian
, I. Petrov
, D. P. Abraham

Research output: Contribution to journal › Article › peer-review

70 Scopus citations

Abstract

The structure of as-prepared Li_1.2Co_0.4Mn _0.4O₂ is studied using a combination of techniques that includes high-resolution electron microscopy (HREM), high-angle annular dark-field imaging in scanning transmission electron microscopy (HAADF-STEM), selected-area electron diffraction (SAED) and electron energy loss spectroscopy (EELS). Electron diffraction and imaging revealed Li ordering in the transition metal planes consistent with the presence of locally monoclinic (Li ₂MnO₃-like) regions with three different topotaxial orientations with respect to a parent rhombohedral (LiCoO₂-like) structure. EELS analyses revealed compositional variations too small to be compatible with perfect, or close to perfect, segregation into pure LiCoO ₂ and Li₂MnO₃ over length scales longer than the sample thickness. We propose a structural model in which Mn and Co segregate within TM planes to form LiMn₆ and Co clusters, which overlap within EELS sampling volumes causing the observed Co/Mn homogeneity.

Original language	English
Pages (from-to)	98-107
Number of pages	10
Journal	Solid State Ionics
Volume	182
Issue number	1
DOIs	https://doi.org/10.1016/j.ssi.2010.11.030
State	Published - Feb 3 2011
Externally published	Yes

Funding

We acknowledge the use of the Center for Microanalysis of Materials (CMM) at the Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign (Illinois), which is partially supported by the U.S. Department of Energy under grant DE-FG02-07ER46453 and DE-FG02-07ER46471. Argonne National Laboratory is a U.S. Department of Energy Office of Science laboratory operated by UChicago Argonne LLC under contract DE-AC02-06CH11357. We are grateful to E. Samman at CMM-Illinois for helpful discussions.

Keywords

EELS
Li ordering
LiCoO
LiMnO
STEM

Access to Document

10.1016/j.ssi.2010.11.030

Cite this

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title = "Analytical electron microscopy of Li1.2Co0.4Mn 0.4O2 for lithium-ion batteries",

abstract = "The structure of as-prepared Li1.2Co0.4Mn 0.4O2 is studied using a combination of techniques that includes high-resolution electron microscopy (HREM), high-angle annular dark-field imaging in scanning transmission electron microscopy (HAADF-STEM), selected-area electron diffraction (SAED) and electron energy loss spectroscopy (EELS). Electron diffraction and imaging revealed Li ordering in the transition metal planes consistent with the presence of locally monoclinic (Li 2MnO3-like) regions with three different topotaxial orientations with respect to a parent rhombohedral (LiCoO2-like) structure. EELS analyses revealed compositional variations too small to be compatible with perfect, or close to perfect, segregation into pure LiCoO 2 and Li2MnO3 over length scales longer than the sample thickness. We propose a structural model in which Mn and Co segregate within TM planes to form LiMn6 and Co clusters, which overlap within EELS sampling volumes causing the observed Co/Mn homogeneity.",

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AU - Wen, J. G.

AU - Bareño, J.

AU - Lei, C. H.

AU - Kang, S. H.

AU - Balasubramanian, M.

AU - Petrov, I.

AU - Abraham, D. P.

PY - 2011/2/3

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N2 - The structure of as-prepared Li1.2Co0.4Mn 0.4O2 is studied using a combination of techniques that includes high-resolution electron microscopy (HREM), high-angle annular dark-field imaging in scanning transmission electron microscopy (HAADF-STEM), selected-area electron diffraction (SAED) and electron energy loss spectroscopy (EELS). Electron diffraction and imaging revealed Li ordering in the transition metal planes consistent with the presence of locally monoclinic (Li 2MnO3-like) regions with three different topotaxial orientations with respect to a parent rhombohedral (LiCoO2-like) structure. EELS analyses revealed compositional variations too small to be compatible with perfect, or close to perfect, segregation into pure LiCoO 2 and Li2MnO3 over length scales longer than the sample thickness. We propose a structural model in which Mn and Co segregate within TM planes to form LiMn6 and Co clusters, which overlap within EELS sampling volumes causing the observed Co/Mn homogeneity.

AB - The structure of as-prepared Li1.2Co0.4Mn 0.4O2 is studied using a combination of techniques that includes high-resolution electron microscopy (HREM), high-angle annular dark-field imaging in scanning transmission electron microscopy (HAADF-STEM), selected-area electron diffraction (SAED) and electron energy loss spectroscopy (EELS). Electron diffraction and imaging revealed Li ordering in the transition metal planes consistent with the presence of locally monoclinic (Li 2MnO3-like) regions with three different topotaxial orientations with respect to a parent rhombohedral (LiCoO2-like) structure. EELS analyses revealed compositional variations too small to be compatible with perfect, or close to perfect, segregation into pure LiCoO 2 and Li2MnO3 over length scales longer than the sample thickness. We propose a structural model in which Mn and Co segregate within TM planes to form LiMn6 and Co clusters, which overlap within EELS sampling volumes causing the observed Co/Mn homogeneity.

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