Defects in Li-rich manganese-based layered oxide: A first-principles study

Abstract

Lithium-rich manganese-based layered oxides are of great interest as cathode materials for lithium ion batteries due to their high energy density. The voltage decay and capacity fading during prolonged charge/discharge cycling are the key obstacles for their practical usage. In this work, using density functional theory, we investigated the origin of the Ni surface segregation by calculating the defect formation energies of antisite defects, including Ni cation substituting a Li cation [Formula: see text] and pairs of Ni cation swapping with Li cation ([Formula: see text]–[Formula: see text]) in [Formula: see text], [Formula: see text] and [Formula: see text] to represent the Mn-rich, Mn–Ni equivalence and Ni-rich conditions, respectively. Results show that [Formula: see text]–[Formula: see text] defect is of energy favorable in Li-rich and Mn-rich layered oxide cathode. Al-doping is beneficial for improving the structure stability and preventing the surface segregation, thus Al-doping can improve cycle ability and rate capability of Li-rich and Mn-rich layered cathodes. This work provides deep insights for the design of layered cathode materials with both high capacity and voltage stability during cycling.