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Please use this identifier to cite or link to this item: http://hdl.handle.net/1942/23272

Title: Effect of annealing atmosphere on LiMn2O4 for thin film Li-ion batteries from aqueous chemical solution deposition
Authors: Maino, Giulia
D`Haen, Jan
Mattelaer, F.
Detavernier, C.
Hardy, An
Van Bael, Marlies K.
Issue Date: 2016
Citation: JOURNAL OF MATERIALS CHEMISTRY A, 4(47), p. 18457-18469
Abstract: In this study we demonstrate and explain the direct relationship between precursor chemistry and phase formation of LiMn2O4 powders and thin films from aqueous chemical solution deposition (CSD). The processing conditions applied to transform the precursor into the LiMn2O4 phase are investigated with a focus on the heating atmosphere and temperature. We found that the Mn2+ ions, used as a starting product, already partially oxidize into Mn3+/Mn4+ in the precursor solution. The Mn3+ ions present in the gel or the dried film are extremely sensitive to O-2, leading to fast oxidation towards Mn4+. Here, we suggest that the oxygen, introduced in the precursor solution by the citrate complexing agent, suffices to oxidize the Mn2+ into Mn3+/Mn4+ which is crucial in the formation of phase pure spinet and stoichiometric LiMn2O4. Any additional oxygen, available as O-2 during the final processing, should be avoided as it leads to further oxidation of the remaining Mn3+ into Mn4+ and to the formation of the gamma-Mn2O3 and lambda-MnO2 secondary phases. Based on these insights, the preparation of phase pure, spinet and stoichiometric LiMn2O4 in a N-2 ambient was achieved both in powders and films. Moreover, the study of the precursor chemistry and final annealing leads to the possibility of reducing the final temperature to 450 degrees C, enabling the use of temperature and oxidation sensitive current collectors such as TiN. This inert ambient and low temperature processing of LiMn2O4 provides the opportunity to have large flexibility and compatibility with process conditions for other materials in the thin film battery stack, without undesired oxidations.
Notes: [Maino, G.; Hardy, A.; Van Bael, M. K.] UHasselt Hasselt Univ, Inst Mat Res IMO IMOMEC, Inorgan & Phys Chem, Agoralaan, B-3590 Diepenbeek, Belgium. [D'Haen, J.] Hasselt Univ, Inst Mat Res, Wetenschapspk 1, B-3590 Diepenbeek, Belgium. [Mattelaer, F.; Detavernier, C.] Univ Ghent, Dept Solid State Sci, Krijgslaan 281 S1, B-9000 Ghent, Belgium. [Hardy, A.; Van Bael, M. K.] IMEC, Div IMOMEC, B-3590 Diepenbeek, Belgium.
URI: http://hdl.handle.net/1942/23272
DOI: 10.1039/c6ta08513j
ISI #: 000390083200030
ISSN: 2050-7488
Category: A1
Type: Journal Contribution
Appears in Collections: Research publications

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