Honeycomb layered oxide as cathodic material for Li- and post-Li batteries: A self-consistent PBE + U study of metal ions (A = Li, Ca, Al) intercalation in bulk SrRu2O6

Abstract

A self-consistent Hubbard-U search is applied for the bulk honeycomb layered oxide SrRu2O6 for a possible proposition of Li and post-Li battery cathode material applications using first-principles density functional theory (DFT) based calculations and analysis. A self-consistent effective value Usc = 4.63 eV yields a reasonable electronic and magnetic ground state of bulk SRO, in lines with the accurate HSE06 functional and other DFT + U studies on the ground state properties. Intercalation of the Li, Ca, and Al metals in the bulk host SRO does not alter the SRO magnetic ordering. All of these guest metals get ionized, and the electrons are transferred to the host and trapped as mono-polarons at the neighbouring Ru sublattices, resulting a quenched magnetic moment at the respective Ru-sublattices (2.2 μB before vs. 1.5 μB after intercalation). A relatively enhanced out-put voltage, 2.3 and 2.0 Volt per electron for Li1+ and Ca2+ respectively, is expected to be guided by the spontaneous self-inductive effect of the host SRO in such layered oxide and the relative electronegativity of these cations. Thus, it might shed light by understanding the fundamental electronic and magnetic properties of SRO for the future domain of the novel battery cathode materials research using layered honeycomb oxides and Earth abundant cations, and allow to go beyond spinel structure oxide cathodes.