Leube, Bernhard T, Inglis, Kenneth K, Carrington, Elliot J, Sharp, Paul M, Shin, J Felix, Neale, Alex R, Manning, Troy D, Pitcher, Michael J, Hardwick, Laurence J, Dyer, Matthew S et al (show 3 more authors)
(2018)
Lithium Transport in Li<sub>4.4</sub><i>M</i><sub>0.4</sub><i>M</i>′<sub>0.6</sub>S<sub>4</sub> (M = Al<SUP>3+</SUP>, Ga<SUP>3+</SUP>, and <i>M</i>′ = Ge<SUP>4+</SUP>, Sn<SUP>4+</SUP>): Combined Crystallographic, Conductivity, Solid State NMR, and Computational Studies.
CHEMISTRY OF MATERIALS, 30 (20).
pp. 7183-7200.
Text
LiAlGeS_resubmission_30-08-18_cleared.pdf - Author Accepted Manuscript Download (13MB) |
Abstract
To understand the structural and compositional factors controlling lithium transport in sulfides, we explored the Li5AlS4-Li4GeS4 phase field for new materials. Both parent compounds are defined structurally by a hexagonal close packed sulfide lattice, where distinct arrangements of tetrahedral metal sites give Li5AlS4 a layered structure and Li4GeS4 a three-dimensional structure related to γ-Li3PO4. The combination of the two distinct structural motifs is expected to lead to new structural chemistry. We identified the new crystalline phase Li4.4Al0.4Ge0.6S4, and investigated the structure and Li+ ion dynamics of the family of structurally related materials Li4.4M0.4M′0.6S4 (M = Al3+, Ga3+ and M′ = Ge4+, Sn4+). We used neutron diffraction to solve the full structures of the Al-homologues, which adopt a layered close-packed structure with a new arrangement of tetrahedral (M/M′) sites and a novel combination of ordered and disordered lithium vacancies. AC impedance spectroscopy revealed lithium conductivities in the range of 3(2) × 10-6 to 4.3(3) × 10-5 S cm-1 at room temperature with activation energies between 0.43(1) and 0.38(1) eV. Electrochemical performance was tested in a plating and stripping experiment against Li metal electrodes and showed good stability of the Li4.4Al0.4Ge0.6S4 phase over 200 h. A combination of variable temperature 7Li solid state nuclear magnetic resonance spectroscopy and ab initio molecular dynamics calculations on selected phases showed that two-dimensional diffusion with a low energy barrier of 0.17 eV is responsible for long-range lithium transport, with diffusion pathways mediated by the disordered vacancies while the ordered vacancies do not contribute to the conductivity. This new structural family of sulfide Li+ ion conductors offers insight into the role of disordered vacancies on Li+ ion conductivity mechanisms in hexagonally close packed sulfides that can inform future materials design.
Item Type: | Article |
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Uncontrolled Keywords: | 3402 Inorganic Chemistry, 3403 Macromolecular and Materials Chemistry, 34 Chemical Sciences, 3406 Physical Chemistry, 40 Engineering, 4016 Materials Engineering |
Depositing User: | Symplectic Admin |
Date Deposited: | 16 Nov 2018 10:58 |
Last Modified: | 20 Jun 2024 16:41 |
DOI: | 10.1021/acs.chemmater.8b03175 |
Open Access URL: | http://10.0.3.253/acs.chemmater.8b03175 |
Related URLs: | |
URI: | https://livrepository.liverpool.ac.uk/id/eprint/3027806 |