(Sub)surface Promoted Disproportionation and Absolute Band Alignment in High-Power LiMn2O4 Cathodes

Scivetti, Ivan and Teobaldi, Gilberto (2015) (Sub)surface Promoted Disproportionation and Absolute Band Alignment in High-Power LiMn2O4 Cathodes. [Data Collection]

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We present an isotropic (Ueff) and anisotropic (U-J) Hubbard and van der Waals (vdW) corrected Density Functional Theory study of bulk and low-index surfaces of lithium manganese oxide LiMn2O4 (LMO), a promising cathode material for high-power Li-ion batteries. Use of anisotropic (U-J) corrections in the simulation of bulk LMO leads to improved agreement with available experimental data, whereas vdW corrections do not affect the results. Carefully converged relaxation of slab geometries indicates that, when vdW-corrections are included, the spinel reconstructed Literminated (111) surface is always energetically favored for both Ueff and (U-J) methods, regardless of the LMO phase. In contrast, neglect of vdW corrections leads to the (001) surface in orthorhombic phase being favored when applying (U-J) corrections. Independently of the simulation protocol and crystalline phase, (111) truncation, reconstructed or not, promotes LMO disproportionation and appearance of Mn+2 cations, without the need of any chemical or electrochemical surface treatment. Absolute band-alignment of the considered surfaces reveals increased reductive propensity for the (111) terminations. Finally, our computational findings are discussed with respect to available data on the observed surface dependence of Mn disproportionation and electrochemical passivation of LMO substrates.

Keywords: Lithium-ion batteries, Lithium Manganese Oxide, Disproportionation, Hubbard corrected Density Functional Theory, Electronic Structure
Divisions: Faculty of Science and Engineering > School of Physical Sciences
Depositing User: Gilberto Teobaldi
Date Deposited: 27 Aug 2015 13:34
Last Modified: 27 Aug 2015 13:34
URI: http://datacat.liverpool.ac.uk/id/eprint/54

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