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Li6SiO4Cl2: A hexagonal argyrodite based on antiperovskite layer stacking

DOI: 10.1021/acs.chemmater.1c00157 DOI Help

Authors: Alexandra Morscher (University of Liverpool) , Matthew S. Dyer (University of Liverpool) , Benjamin B. Duff (University of Liverpool) , Guopeng Han (University of Liverpool) , Jacinthe Gamon (University of Liverpool) , Luke Daniels (University of Liverpool) , Yun Dang (University of Liverpool) , T. Wesley Surta (University of Liverpool) , Craig M. Robertson (University of Liverpool) , Frédéric Blanc (University of Liverpool) , John B. Claridge (University of Liverpool) , Matthew J. Rosseinsky (University of Liverpool)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Chemistry Of Materials

State: Published (Approved)
Published: March 2021
Diamond Proposal Number(s): 23666

Open Access Open Access

Abstract: 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.

Journal Keywords: Chemical structure; Anions; Layers; Lithium; Ions

Subject Areas: Materials, Chemistry

Instruments: I11-High Resolution Powder Diffraction


Discipline Tags:

Physical Chemistry Material Sciences Chemistry

Technical Tags:

Diffraction X-ray Powder Diffraction