Conflicting Role of Inversion of the LiMn₂O₄ Spinel on Lithium-Ion Battery Capacity from First-Principles Calculations

The inversion (Li and Mn interchanging sites) of cathode material LiMn 2 O 4 (LMO) on the battery capacity is studied from the perspective of Jahn–Teller distortion (JTD) and manganese dissolution. The LMO spinel in the orthorhombic structure with anti-ferromagnetic ordering is studied using spin-polarized density functional theory calculations with anisotropic ( U – J ) corrections. The charge orderings and magnetic moments of the orthorhombic LMO spinel at normal, half-inverse, and full-inverse structures are connected with the battery’s properties. It is found that the magnetic moments prefer high spin states in all the cases, and the JTD is mainly due to Mn 3+ . The existence of Mn 3+ at octahedral and tetrahedral sites in normal and full-inverse LMO spinel, respectively, induces strong JTD that will reduce the battery capacity. In half-inverse LMO spinel, the cubic-like phase with degraded JTD could retard the capacity decay of lithium-ion batteries, while the existence of Mn A 2+ at the tetrahedral sites would aggravate the manganese dissolution and exacerbate the capacity decay. In all, inversion in LMO does not always have a negative effect on battery capacity as JTD and Mn 2+ manganese dissolution compete with each other.