Ordered Oxygen Vacancies in the Lithium-Rich Oxide Li<sub>4</sub>CuSbO<sub>5.5</sub>, a Triclinic Structure Type Derived from the Cubic Rocksalt Structure

Perez, Arnaud J, Vasylenko, Andrij, Surta, T Wesley, Niu, Hongjun, Daniels, Luke M, Hardwick, Laurence J, Dyer, Matthew S, Claridge, John B and Rosseinsky, Matthew J
(2021) Ordered Oxygen Vacancies in the Lithium-Rich Oxide Li<sub>4</sub>CuSbO<sub>5.5</sub>, a Triclinic Structure Type Derived from the Cubic Rocksalt Structure. INORGANIC CHEMISTRY, 60 (24). pp. 19022-19034.

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Li-rich rocksalt oxides are promising candidates as high-energy density cathode materials for next-generation Li-ion batteries because they present extremely diverse structures and compositions. Most reported materials in this family contain as many cations as anions, a characteristic of the ideal cubic closed-packed rocksalt composition. In this work, a new rocksalt-derived structure type is stabilized by selecting divalent Cu and pentavalent Sb cations to favor the formation of oxygen vacancies during synthesis. The structure and composition of the oxygen-deficient Li<sub>4</sub>CuSbO<sub>5.5</sub>□<sub>0.5</sub> phase is characterized by combining X-ray and neutron diffraction, ICP-OES, XAS, and magnetometry measurements. The ordering of cations and oxygen vacancies is discussed in comparison with the related Li<sub>2</sub>CuO<sub>2</sub>□<sub>1</sub> and Li<sub>5</sub>SbO<sub>5</sub>□<sub>1</sub> phases. The electrochemical properties of this material are presented, with only 0.55 Li<sup>+</sup> extracted upon oxidation, corresponding to a limited utilization of cationic and/or anionic redox, whereas more than 2 Li<sup>+</sup> ions can be reversibly inserted upon reduction to 1 V vs Li<sup>+</sup>/Li, a large capacity attributed to a conversion reaction and the reduction of Cu<sup>2+</sup> to Cu<sup>0</sup>. Control of the formation of oxygen vacancies in Li-rich rocksalt oxides by selecting appropriate cations and synthesis conditions affords a new route for tuning the electrochemical properties of cathode materials for Li-ion batteries. Furthermore, the development of material models of the required level of detail to predict phase diagrams and electrochemical properties, including oxygen release in Li-rich rocksalt oxides, still relies on the accurate prediction of crystal structures. Experimental identification of new accessible structure types stabilized by oxygen vacancies represents a valuable step forward in the development of predictive models.

Item Type: Article
Uncontrolled Keywords: 3402 Inorganic Chemistry, 34 Chemical Sciences, 3406 Physical Chemistry, 7 Affordable and Clean Energy
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Symplectic Admin
Date Deposited: 20 Jan 2022 10:36
Last Modified: 20 Jun 2024 19:09
DOI: 10.1021/acs.inorgchem.1c02882
Open Access URL: https://doi.org/10.1021/acs.inorgchem.1c02882
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URI: https://livrepository.liverpool.ac.uk/id/eprint/3147255