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Atomistic Simulation and Characterization of Spinel Li\(_{1+x}\)Mn\(_2\)O\(_4\) (0 ≤ x ≤ 1) Nanoparticles

Ledwaba, Raesibe S., Sayle, Dean C., Ngoepe, Phuti E. (2020) Atomistic Simulation and Characterization of Spinel Li\(_{1+x}\)Mn\(_2\)O\(_4\) (0 ≤ x ≤ 1) Nanoparticles. ACS Applied Energy Materials, 3 . pp. 1429-1438. ISSN 2574-0962. (doi:10.1021/acsaem.9b01870) (KAR id:80393)

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Abstract

Lithium-ion batteries, comprising nanoparticulate Ni–Mn–Co (NMC) cathodes that have been used to power electric vehicles, can be improved by blending NMC with Li–Mn–O (LMO). However, LMO undergoes a cubic to tetragonal phase change during charge cycling, which cracks and pulverizes the material, resulting in capacity fading. Structural characterization during the phase transition is the first step in mitigating capacity fading and can be challenging experimentally and computationally. Here, we use simulated amorphization and crystallization to generate atom-level models of the LMO nanoparticles. This simulation strategy does not require any structural information to be predetermined. Instead, the structures evolve “naturally” from amorphous precursors. Analysis of the model Li–Mn–O nanoparticles reveals that they comprise domains of defect-rich spinel, Mn\(_3\)O\(_4\), layered Li\(_2\)MnO\(_3\), and lithium-rich spinel Li\(_{1+x}\)Mn\(_{2–x}\)O\(_4\) phases together with complex microstructural features. The discharge process was modeled by inserting surplus lithium atoms into the nanoparticles, resulting in structural changes, accompanied by a variety of constituent polymorphs. A transitional multigrained structure, between the cubic (Li\(_1\)Mn\(_2\)O\(_4\)) and tetragonal (Li\(_2\)Mn\(_2\)O\(_4\)) phases, is observed at Li\(_{1.75}\)Mn\(_2\)O\(_4\). We also find that microstructural features, such as microtwinning and intrinsic dopants, vacancies, etc., result in a network of Li transport pathways, enabling Li mobility in all three spatial directions.

Item Type: Article
DOI/Identification number: 10.1021/acsaem.9b01870
Uncontrolled keywords: lithium-ion batteries, nanoparticles, phase transition, discharge
Subjects: Q Science > QC Physics > QC173.45 Condensed Matter
Q Science > QD Chemistry > QD478 Solid State Chemistry
Divisions: Divisions > Division of Natural Sciences > Physics and Astronomy
Depositing User: Dean Sayle
Date Deposited: 07 Mar 2020 08:47 UTC
Last Modified: 16 Feb 2021 14:11 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/80393 (The current URI for this page, for reference purposes)
Sayle, Dean C.: https://orcid.org/0000-0001-7227-9010
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