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Lithium Ion Mobility in Lithium Phosphidosilicates: Crystal Structure, 7 Li, 29 Si, and 31 P MAS NMR Spectroscopy, and Impedance Spectroscopy of Li 8 SiP 4 and Li 2 SiP 2
Author(s) -
Toffoletti Lorenzo,
Kirchhain Holger,
Landesfeind Johannes,
Klein Wilhelm,
van Wüllen Leo,
Gasteiger Hubert A.,
Fässler Thomas F.
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201602903
Subject(s) - lithium (medication) , nuclear magnetic resonance spectroscopy , crystallography , spectroscopy , solid state nuclear magnetic resonance , ion , chemistry , crystal structure , isotopes of lithium , dielectric spectroscopy , analytical chemistry (journal) , materials science , ion exchange , electrode , nuclear magnetic resonance , stereochemistry , electrochemistry , medicine , physics , organic chemistry , quantum mechanics , chromatography , endocrinology
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, Li 8 SiP 4 and Li 2 SiP 2 , 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 −6 Scm −1 at 0 °C to 1.2(2)×10 −4 Scm −1 at 75 °C (Li 8 SiP 4 ) and from 6.1(7)×10 −8 Scm −1 at 0 °C to 6(1)×10 −6 Scm −1 at 75 °C (Li 2 SiP 2 ), as determined by impedance measurements. Temperature‐dependent solid‐state 7 Li NMR spectroscopy revealed low activation energies of about 36 kJ mol −1 for Li 8 SiP 4 and about 47 kJ mol −1 for Li 2 SiP 2 . Both compounds were structurally characterized by X‐ray diffraction analysis (single crystal and powder methods) and by 7 Li, 29 Si, and 31 P MAS NMR spectroscopy. Both phases consist of tetrahedral SiP 4 anions and Li counterions. Li 8 SiP 4 contains isolated SiP 4 units surrounded by Li atoms, while Li 2 SiP 2 comprises a three‐dimensional network based on corner‐sharing SiP 4 tetrahedra, with the Li ions located in cavities and channels.