Li<sub>4.3</sub>AlS<sub>3.3</sub>Cl<sub>0.7</sub>: A Sulfide-Chloride Lithium Ion Conductor with Highly Disordered Structure and Increased Conductivity



Gamon, Jacinthe, Dyer, Matthew S, Duff, Benjamin B, Vasylenko, Andrij, Daniels, Luke M, Zanella, Marco, Gaultois, Michael W, Blanc, Frederic, Claridge, John B and Rosseinsky, Matthew J
(2021) Li<sub>4.3</sub>AlS<sub>3.3</sub>Cl<sub>0.7</sub>: A Sulfide-Chloride Lithium Ion Conductor with Highly Disordered Structure and Increased Conductivity. CHEMISTRY OF MATERIALS, 33 (22). pp. 8733-8744.

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Abstract

Mixed anion materials and anion doping are very promising strategies to improve solid-state electrolyte properties by enabling an optimized balance between good electrochemical stability and high ionic conductivity. In this work, we present the discovery of a novel lithium aluminum sulfide-chloride phase, obtained by substitution of chloride for sulfur in Li<sub>3</sub>AlS<sub>3</sub> and Li<sub>5</sub>AlS<sub>4</sub> materials. The structure is strongly affected by the presence of chloride anions on the sulfur site, as the substitution was shown to be directly responsible for the stabilization of a higher symmetry phase presenting a large degree of cationic site disorder, as well as disordered octahedral lithium vacancies. The effect of disorder on the lithium conductivity properties was assessed by a combined experimental-theoretical approach. In particular, the conductivity is increased by a factor 10<sup>3</sup> compared to the pure sulfide phase. Although it remains moderate (10<sup>-6</sup> S·cm<sup>-1</sup>), ab initio molecular dynamics and maximum entropy (applied to neutron diffraction data) methods show that disorder leads to a 3D diffusion pathway, where Li atoms move thanks to a concerted mechanism. An understanding of the structure-property relationships is developed to determine the limiting factor governing lithium ion conductivity. This analysis, added to the strong step forward obtained in the determination of the dimensionality of diffusion, paves the way for accessing even higher conductivity in materials comprising an <i>hcp</i> anion arrangement.

Item Type: Article
Uncontrolled Keywords: 40 Engineering, 4016 Materials Engineering, 34 Chemical Sciences, 3406 Physical Chemistry
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 08 Dec 2021 15:30
Last Modified: 20 Jun 2024 19:09
DOI: 10.1021/acs.chemmater.1c02751
Open Access URL: https://pubs.acs.org/doi/10.1021/acs.chemmater.1c0...
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3144975