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Title: Simulation of the surface structure of lithium manganese oxide spinel.

Abstract

Simulations of the surface structure of low-index surfaces of LiMn{sub 2}O{sub 4} (LMO), a candidate Li-ion battery electrode material, have been performed within the 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{sub 2}O{sub 4} that showed the Mg-terminated (001) surface to be lowest in energy.

Authors:
;  [1]
  1. Chemical Sciences and Engineering Division
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
EE
OSTI Identifier:
1018504
Report Number(s):
ANL/CSE/JA-69811
Journal ID: 1098-0121; TRN: US201114%%35
DOE Contract Number:  
DE-AC02-06CH11357
Resource Type:
Journal Article
Journal Name:
Phys. Rev. B
Additional Journal Information:
Journal Volume: 83; Journal Issue: 19 ; May 31, 2011
Country of Publication:
United States
Language:
ENGLISH
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; DIPOLE MOMENTS; DISSOLUTION; ELECTRODES; GEOMETRY; LITHIUM; MANGANESE OXIDES; ORIENTATION; PHASE SPACE; RELAXATION; SIMULATION; STOICHIOMETRY; VACANCIES; VALENCE; VULNERABILITY

Citation Formats

Benedek, R, and Thackeray, M M. Simulation of the surface structure of lithium manganese oxide spinel.. United States: N. p., 2011. Web. doi:10.1103/PhysRevB.83.195439.
Benedek, R, & Thackeray, M M. Simulation of the surface structure of lithium manganese oxide spinel.. United States. https://doi.org/10.1103/PhysRevB.83.195439
Benedek, R, and Thackeray, M M. 2011. "Simulation of the surface structure of lithium manganese oxide spinel.". United States. https://doi.org/10.1103/PhysRevB.83.195439.
@article{osti_1018504,
title = {Simulation of the surface structure of lithium manganese oxide spinel.},
author = {Benedek, R and Thackeray, M M},
abstractNote = {Simulations of the surface structure of low-index surfaces of LiMn{sub 2}O{sub 4} (LMO), a candidate Li-ion battery electrode material, have been performed within the 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{sub 2}O{sub 4} that showed the Mg-terminated (001) surface to be lowest in energy.},
doi = {10.1103/PhysRevB.83.195439},
url = {https://www.osti.gov/biblio/1018504}, journal = {Phys. Rev. B},
number = 19 ; May 31, 2011,
volume = 83,
place = {United States},
year = {Tue May 31 00:00:00 EDT 2011},
month = {Tue May 31 00:00:00 EDT 2011}
}