Mechanism of Magnesium Transport in Spinel Chalcogenides. Issue 12 (4th August 2021)

• Record Type: Journal Article
• Authors: Sotoudeh, Mohsen; Dillenz, Manuel; Groß, Axel
• Is Part Of: Advanced energy & sustainability research. Volume 2:Issue 12(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-04
• Subjects: density functional theory -- ion conductivity -- magnesium batteries -- ternary spinel chalcogenides; Renewable energy sources -- Periodicals; Environmental sciences -- Periodicals; Sustainable development -- Periodicals; 621.042
• DOI: 10.1002/aesr.202100113
• Languages: English
• ISSNs: 2699-9412

Abstract

Abstract : Batteries based on multivalent ions such as magnesium have been attracting considerable attention due to their potential for high energy densities, but their low ion mobility remains an obstacle. Herein, ionic conductivity in spinel host materials, which represent a promising class of cathode and solid‐electrolyte materials in batteries, is addressed. Based on periodic density functional theory calculations, the important parameters that determine the mobility and insertion of ions are identified. In particular, the critical role that trigonal distortions of the spinel structure play for the ion mobility is highlighted. It is shown that it is the competition between coordination and bond length that governs the Mg site preference in spinel compounds upon trigonal distortions. This can only be understood by also taking covalent interactions into account. This reveals that purely ionic concepts are not sufficient to understand mobility in crystalline battery materials. Furthermore, the calculations suggest that anionic redox plays a much more important role in sulfide and selenide spinels than in oxide spinels. The findings shed light on the fundamentional mechanisms underlying ionic conductivity in solid hosts and thus may contribute to improvement of ion transport in battery electrodes. Abstract : Ion mobility in electrodes and electrolytes is a critical performance parameter for batteries. Herein, using first‐principles electronic structure calculations, the factors underlying the migration and site preference of ions in spinel chalcogenides are determined. It is demonstrated that a purely ionic picture of the interaction in crystalline battery materials falls short of providing a complete understanding of ionic conductivity.