Systematic density functional theory investigations on cubic lithium-rich iron-based Li2FeO3: A multiple electrons cationic and anionic redox cathode material

Abstract

Lithium-rich materials with multi-electron redox processes are promising for high energy density lithium-ion batteries. However, the layered manganese-based lithium-rich materials that have been widely studied still have many drawbacks. Studies of new non-layered lithium-rich materials can deepen the understanding of multi-electron redox processes mechanism of the combination of anion and cation. Herein, detailed density functional theory investigations based on the first-principles calculations of cubic lithium-rich iron-based Li 2 FeO 3 are reported. The ground-state Li/vacancy configurations of Li 2− x FeO 3 (0 ≤ x ≤ 2) at nine Li concentrations are determined, from which the delithiation potential is calculated as ∼4.3 V vs . Li + /Li. According to the Li/vacancy configuration in each ground state, the sequence of lithium removal is suggested from an energetic view. Bader charge and spin calculations suggest the charge compensation during Li removal is divided into two stages. Specifically, Fe 4+ is oxidized to Fe 5+ during the first Li ion extraction per formula unit, while the second Li ion extraction triggered the oxygen redox exclusively. This work emphasizes the guiding and predictive role of theoretical calculations for the discovery of new cathode materials for lithium batteries, and can certainly be expanded to other material systems. • A non-layered lithium-rich cathode material is proposed. • Cationic and anionic redox reactions are combined. • The mechanism relies on two types of Li local structures.