Mechanism of Magnesium Transport in Spinel Chalcogenides

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