title: Ionic Pathways in Li13Si4 investigated by (6)Li and (7)Li solid state NMR experiments.
abstract: Local environments and dynamics of lithium ions in the binary lithium silicide Li13Si4 have been studied by (6)Li MAS-NMR, (7)Li spin-lattice relaxation time and site-resolved (7)Li 2D exchange NMR measurements as a function of mixing time. Variable temperature experiments result in distinct differences in activation energies characterizing the transfer rates between the different lithium sites. Based on this information, a comprehensive picture of the preferred ionic transfer pathways in this silicide has been developed. With respect to local mobility, the results of the present study suggests the ordering Li6/Li7>Li5>Li1>Li4 >Li2/Li3. Mobility within the z=0.5 plane is distinctly higher than within the z=0 plane, and the ionic transfer between the planes is most facile via Li1/Li5 exchange. The lithium ionic mobility can be rationalized on the basis of the type of the coordinating silicide anions and the lithium-lithium distances within the structure. Lithium ions strongly interacting with the isolated Si(4-) anions have distinctly lower mobility than those the coordination of which is dominated by Si2(6-) dumbbells.
authors.affiliation: Institut für Physikalische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Dupke
authors.affiliation: Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany.
authors.forename: Thorsten
authors.initials: T
authors.lastname: Langer
authors.affiliation: Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Winter
authors.affiliation: Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany.
authors.forename: Rainer
authors.initials: R
authors.lastname: Pöttgen
authors.affiliation: Institut für Physikalische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Winter
authors.affiliation: Institut für Physikalische Chemie, Universität Münster, Corrensstrasse 30, 48149 Münster, Germany; Institute of Physics in São Carlos, University of São Paulo, Av. Trabalhador Sãocarlense 400, 13590 São Carlos, SP, Brazil. Electronic address: eckerth@uni-muenster.de.
authors.forename: Hellmut
authors.initials: H
authors.lastname: Eckert
keywords: 2D-exchange NMR; Li ion batteries; Li silicides; Spin-lattice relaxation; lithium ion conductors