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Simulation of Aqueous Dissolution of Lithium Manganate Spinel from First Principles

Autor(en)
Roy Benedek, Michael M Thackeray, John Low, Tomas Bucko
Abstrakt

Constrained density functional theory at the GGA+U level, within

the Blue Moon ensemble, as implemented in the VASP code, is applied to

simulate aqueous dissolution of lithium manganate spinel, a candidate

cathode material for lithium ion batteries. Ions are dissolved from

stoichiometric slabs of composition LiMn2O4, with

orientations (001) and (110), embedded in a cell with 20 Å water

channels between periodically repeated slabs. Analysis of the Blue Moon

ensemble forces for dissolution of Li, Mn, and O ions from lithium

manganate indicate that bond breaking occurs sequentially, ordered from

weak to strong bonds, where bond breaking occurs when a bond length is

stretched about 50% relative to its equilibrium value. Substrate ions

are displaced to maintain bond lengths close to equilibrium for bonds

other than that the one being broken. The predicted free energies

required to break the chemical bonds with the LiMn2O4 substrate are Mn3+, 1.4; O2–, 1.0; Mn2+, 0.8; and Li+, 0.35, in eV; an existing experimental measurement (Lu, C. H.; Lin, S. W. J. Mater. Res.2002, 17,

1476) had yielded an effective dissolution activation energy of 0.7 eV.

A mechanism for the role of acid in promoting lithium manganate

dissolution is discussed.

Organisation(en)
Computergestützte Materialphysik
Externe Organisation(en)
Argonne National Laboratory
Journal
The Journal of Physical Chemistry Part C (Nanomaterials and Interfaces)
Band
116
Seiten
4050-4059
Anzahl der Seiten
10
ISSN
1932-7447
DOI
https://doi.org/10.1021/jp208793k
Publikationsdatum
2012
Peer-reviewed
Ja
ÖFOS 2012
103018 Materialphysik
Sustainable Development Goals
SDG 7 – Bezahlbare und saubere Energie
Link zum Portal
https://ucrisportal.univie.ac.at/de/publications/bc3ab016-c4fc-47fe-8acd-10b9589c4b5f