Computationally-guided discovery of a new compound in the Li-Al-S phase field, Li3AlS3: structure and lithium conductivity

Gamon, Jacinthe, Duff, Benjamin, Dyer, Matthew, Collins, Chris, Daniels, Luke, Surta, Wesley, Sharp, Paul, Gaultois, Michael, Blanc, Frederic, Claridge, John and Rosseinsky, Matthew (2019) Computationally-guided discovery of a new compound in the Li-Al-S phase field, Li3AlS3: structure and lithium conductivity. [Data Collection]

Data Catalogue DOI: 10.17638/datacat.liverpool.ac.uk/988

Original publication URL: https://doi.org/10.1021/acs.chemmater.9b03230

Description

With the goal of finding new lithium solid electrolytes by a combined computational-experimental method, the exploration of the Li-Al-O-S phase field resulted in the discovery of a new sulphide Li3AlS3. The structure of the new phase was determined through an approach combining synchrotron X-ray and neutron diffraction with 6Li and 27Al magic angle spinning nuclear magnetic resonance spectroscopy, and revealed a highly ordered cationic polyhedral network within a sulphide anion hcp-type sublattice. The originality of the structure relies on the presence of Al2S6 repeating dimer units consisting of two edge-shared Al tetrahedra. We find that, in this structure type consisting of alternating tetrahedral layers with Li-only polyhedra layers, the formation of these dimers is constrained by the Al/S ratio of 1/3. Moreover, by comparing this structure to similar phases such as Li5AlS4 and Li4.4Al0.2Ge0.3S4 ((Al+Ge)/S = 1/4), we discovered that the AlS4 dimers not only influence atomic displacements and Li polyhedral distortions, but also determine the overall Li polyhedral arrangement within the hcp lattice, leading to the presence of highly ordered vacancies in both the tetrahedral and Li-only layer. AC-impedance measurements revealed a low lithium mobility, which is strongly impacted by the presence of ordered vacancies. Finally, a composition-structure-property relationship understanding was developed to explain the extent of lithium mobility in this structure type.

Keywords:

solid electrolyte, sulfide, lithium ionic conductivity

Divisions:

Faculty of Science and Engineering > School of Physical Sciences

Depositing User:

Jacinthe Gamon

Date Deposited:

21 Nov 2019 10:36

Last Modified:

28 Nov 2019 11:06

DOI:

10.17638/datacat.liverpool.ac.uk/988