Li6SiO4Cl2: A Hexagonal Argyrodite Based on Antiperovskite Layer Stacking

Morscher, Alexandra, Dyer, Matthew, Duff, Benjamin, Han, Guopeng, Gamon, Jacinthe, Daniels, Luke, Dang, Yun, Surta, Wesley, Robertson, Craig, Blanc, Frederic, Claridge, John and Rosseinsky, Matthew (2020) Li6SiO4Cl2: A Hexagonal Argyrodite Based on Antiperovskite Layer Stacking. [Data Collection]

Description

A hexagonal analogue, Li6SiO4Cl2, of the cubic lithium argyrodite family of solid electrolytes is isolated by a computation–experiment approach. We show that the argyrodite structure is equivalent to the cubic antiperovskite solid electrolyte structure through anion site and vacancy ordering within a cubic stacking of two close-packed layers. Construction of models that assemble these layers with the combination of hexagonal and cubic stacking motifs, both well known in the large family of perovskite structural variants, followed by energy minimization identifies Li6SiO4Cl2 as a stable candidate composition. Synthesis and structure determination demonstrate that the material adopts the predicted lithium site-ordered structure with a low lithium conductivity of ∼10–10 S cm–1 at room temperature and the predicted hexagonal argyrodite structure above an order–disorder transition at 469.3(1) K. This transition establishes dynamic Li site disorder analogous to that of cubic argyrodite solid electrolytes in hexagonal argyrodite Li6SiO4Cl2 and increases Li-ion mobility observed via NMR and AC impedance spectroscopy. The compositional flexibility of both argyrodite and perovskite alongside this newly established structural connection, which enables the use of hexagonal and cubic stacking motifs, identifies a wealth of unexplored chemistry significant to the field of solid electrolytes.

Keywords: Chemical Structure, Anions, Layers, Lithium ion conductor, Crystallography, Crystal Chemistry, Argyrodite, Perovskite
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Luke Daniels
Date Deposited: 04 May 2021 13:53
Last Modified: 04 May 2021 13:53
DOI: 10.17638/datacat.liverpool.ac.uk/1158
URI: https://datacat.liverpool.ac.uk/id/eprint/1158

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