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; O^2–, 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