title: Characterization of thin films of the solid electrolyte Li(x)Mg(1-2x)Al(2+x)O4 (x = 0, 0.05, 0.15, 0.25).
abstract: RF-sputtered thin films of spinel Li(x)Mg(1-2x)Al(2+x)O4 were investigated for use as solid electrolyte. The usage of this material can enable the fabrication of a lattice matched battery stack, which is predicted to lead to superior battery performance. Spinel Li(x)Mg(1-2x)Al(2+x)O4 thin films, with stoichiometry (x) ranging between 0 and 0.25, were formed after a crystallization anneal as shown by X-ray diffraction and transmission electron microscopy. The stoichiometry of the films was evaluated by elastic recoil detection and Rutherford backscattering and found to be slightly aluminum rich. The excellent electronic insulation properties were confirmed by both current-voltage measurements as well as by copper plating tests. The electrochemical stability window of the material was probed using cyclic voltammetry. Lithium plating and stripping was observed together with the formation of a Li-Pt alloy, indicating that Li-ions passed through the film. This observation contradicted with impedance measurements at open circuit potential, which showed no apparent Li-ion conductivity of the film. Impedance spectroscopy as a function of potential showed the occurrence of Li-ion intercalation into the Li(x)Mg(1-2x)Al(2+x)O4 layers. When incorporating Li-ions in the material the ionic conductivity can be increased by 3 orders of magnitude. Therefore it is anticipated that the response of Li(x)Mg(1-2x)Al(2+x)O4 is more adequate for a buffer layer than as the solid electrolyte.
authors.affiliation: Imec, Kapeldreef 75, 3001 Leuven, Belgium. brecht.put@imec.be and KU Leuven Department of Physics and Astronomy, Celestijnenlaan 200D, 3001 Leuven, Belgium.
authors.forename: Brecht
authors.initials: B
authors.lastname: Put
authors.affiliation: Imec, Kapeldreef 75, 3001 Leuven, Belgium. brecht.put@imec.be and KU Leuven Centre for surface Chemistry and Catalysis, Kasteelpark Arenberg 23, 3001 Leuven, Belgium.
authors.forename: Philippe M
authors.initials: PM
authors.lastname: Vereecken
authors.affiliation: Imec, Kapeldreef 75, 3001 Leuven, Belgium. brecht.put@imec.be.
authors.forename: Maarten J
authors.initials: MJ
authors.lastname: Mees
authors.affiliation: Imec, Kapeldreef 75, 3001 Leuven, Belgium. brecht.put@imec.be and Toyota Europe - Hoge Wei 33 - Technical Centre B - 1930 Zaventem, Belgium.
authors.forename: Fabio
authors.initials: F
authors.lastname: Rosciano
authors.affiliation: Imec, Kapeldreef 75, 3001 Leuven, Belgium. brecht.put@imec.be.
authors.forename: Iuliana P
authors.initials: IP
authors.lastname: Radu
authors.affiliation: KU Leuven Department of Physics and Astronomy, Celestijnenlaan 200D, 3001 Leuven, Belgium.
authors.forename: Andre
authors.initials: A
authors.lastname: Stesmans