Multicomponent Effects on the Crystal Structures and Electrochemical Properties of Spinel-Structured M3O4 (M = Fe, Mn, Co) Anodes in Lithium Rechargeable Batteries

The structural and electrochemical properties of the multicomponent oxide MnFeCoO4, which has a cubic spinel AB(2)O(4) structure, are studied experimentally and by using first principles calculations. A solid solution of the spinels Mn3O4, Fe3O4, and Co3O4 forms the spine! MnFeCoO4, with Co preferentially occupying tetrahedral sites (A site). First principles calculations predict that the valence states of each transition metal would shift from +8/3 for the single component oxide to +3, +3, and +2 for the Mn, Fe, and Co ions, respectively, in the mixed spinel. The charge ordering of the transition metals (Co2+ vs Mn3+, Fe3+) in the multicomponent oxide is speculated to be the reason for the strong preference of Co for the A site. As a result, the characteristic redox potential of each transition metal shifted, as demonstrated in an anode test of the multicomponent oxide in a lithium cell. This represents an example how the electrochemical performance could be tuned by multicomponent substitution.