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Simulations of the surface structure of low-index surfaces of LiMn${}_{2}$O${}_{4}$ (LMO), a candidate Li-ion battery electrode material, have been performed within the $\text{GGA}+U$ approximation, using the VASP code. Surfaces of (001), (110), and (111) orientation were considered, with at least two terminations treated in each case. A slab geometry was employed, with termination-layer vacancies introduced to remove the bulk dipole moment while maintaining ideal stoichiometry. To complement static-structure relaxation calculations, molecular-dynamics simulations were performed to explore the phase space of possible surface reconstructions. A reconstruction is predicted for the Mn-terminated (111) surface, in which the top layers mix in stoichiometric proportions to form an LMO termination layer with square-planar-coordinated Mn. Average surface Mn oxidation states are reduced, relative to the bulk, for all surfaces considered, as a consequence of the lower-energy cost of Jahn-Teller distortion at the surface. Threefold-coordinated surface Mn, found for two terminations, is divalent, which may enhance its vulnerability to dissolution. The Li-terminated (001) surface is lowest in energy, consistent with previous classical-potential simulations for MgAl${}_{2}$O${}_{4}$ that showed the Mg-terminated (001) surface to be lowest in energy.

Simulation of the surface structure of lithium manganese oxide spinel