Premium
Surface and bulk composition of lithium manganese oxides
Author(s) -
Regan E.,
Groutso T.,
Metson J. B.,
Steiner R.,
Ammundsen B.,
Hassell D.,
Pickering P.
Publication year - 1999
Publication title -
surface and interface analysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.52
H-Index - 90
eISSN - 1096-9918
pISSN - 0142-2421
DOI - 10.1002/(sici)1096-9918(199912)27:12<1064::aid-sia676>3.0.co;2-s
Subject(s) - monoclinic crystal system , orthorhombic crystal system , x ray photoelectron spectroscopy , manganese , spinel , lithium (medication) , materials science , chemistry , crystallography , inorganic chemistry , crystal structure , chemical engineering , metallurgy , medicine , engineering , endocrinology
Lithium manganese oxides, and in particular the spinel‐structured LiMn 2 O 4 , have been investigated as potential active cathode materials for lithium ion batteries. Recently both orthorhombic and monoclinic LiMnO 2 have attracted considerable attention. It has been reported that Al doping allows the preparation of monoclinic LiAl x Mn 1− x O 2 under suitable reaction conditions, and furthermore improves the capacity retention of both o‐LiAl x Mn 1− x O 2 and m‐LiAl x Mn 1− x O 2 . The aim of this study was to elucidate the structural effects of Al doping with particular attention to the surface properties of the material. X‐ray diffraction data reveal that Al induces monoclinic stacking faults in orthorhombic LiAl x Mn 1− x O 2 and at Al contents of ∼5% the preferred cation ordering becomes that of monoclinic LiAl x Mn 1− x O 2 . X‐ray photoelectron spectroscopy measurements show that the Al is homogeneously incorporated throughout the grains up to its solubility limit, and no surface enrichment of Al is observed. The XPS data indicate that Mn in the near‐surface region of the material is predominantly present in its +3 oxidation state, even when annealed to temperatures of up to 250 °C. Copyright © 1999 John Wiley & Sons, Ltd.