title: Lithium Ion Mobility in Lithium Phosphidosilicates: Crystal Structure,7Li,29Si, and31P MAS NMR Spectroscopy, and Impedance Spectroscopy of Li8SiP4and Li2SiP2.
abstract: The need to improve electrodes and Li-ion conducting materials for rechargeable all-solid-state batteries has drawn enhanced attention to the investigation of lithium-rich compounds. The study of the ternary system Li-Si-P revealed a series of new compounds, two of which, Li8SiP4and Li2SiP2, are presented. Both phases represent members of a new family of Li ion conductors that display Li ion conductivity in the range from 1.15(7)×10-6Scm-1at 0 °C to 1.2(2)×10-4Scm-1at 75 °C (Li8SiP4) and from 6.1(7)×10-8Scm-1at 0 °C to 6(1)×10-6Scm-1at 75 °C (Li2SiP2), as determined by impedance measurements. Temperature-dependent solid-state7Li NMR spectroscopy revealed low activation energies of about 36 kJ mol-1for Li8SiP4and about 47 kJ mol-1for Li2SiP2. Both compounds were structurally characterized by X-ray diffraction analysis (single crystal and powder methods) and by7Li,29Si, and31P MAS NMR spectroscopy. Both phases consist of tetrahedral SiP4anions and Li counterions. Li8SiP4contains isolated SiP4units surrounded by Li atoms, while Li2SiP2comprises a three-dimensional network based on corner-sharing SiP4tetrahedra, with the Li ions located in cavities and channels.
authors: Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching bei München, Germany.
authors: Lorenzo
authors: L
authors: Toffoletti
authors: Department of Physics, University of Augsburg, Universitätsstrasse 1, 86159, Augsburg, Germany.
authors: Holger
authors: H
authors: Kirchhain
authors: Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching bei München, Germany.
authors: Johannes
authors: J
authors: Landesfeind
authors: Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching bei München, Germany.
authors: Wilhelm
authors: W
authors: Klein
authors: Department of Physics, University of Augsburg, Universitätsstrasse 1, 86159, Augsburg, Germany.
authors: Leo
authors: L
authors: van Wüllen
authors: Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching bei München, Germany.
authors: Hubert A
authors: HA
authors: Gasteiger
authors: Department of Chemistry, Technische Universität München, Lichtenbergstrasse 4, 85747, Garching bei München, Germany.
authors: Thomas F
authors: http://orcid.org/0000-0001-9460-8882
authors: TF
authors: Fässler
keywords: ionic conductors; lithium; phosphorus; silicon; ternary phases