LiMSO4F (M = Fe, Co and Ni): promising new positive electrode materials through the DFT microscope

A theoretical study of the lithium intercalated LiMSO 4 F and deintercalated MSO 4 F systems, where M = Fe, Co and Ni has been performed within the framework of density functional theory. Beyond predictions of structural evolution and average voltages versus a lithium electrode, we have applied part...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2010-01, Vol.12 (47), p.15512-15522
Main Authors: Frayret, Christine, Villesuzanne, Antoine, Spaldin, Nicola, Bousquet, Eric, Chotard, Jean-Noël, Recham, Nadir, Tarascon, Jean-Marie
Format: Article
Language:English
Subjects:
Charge
Electric potential
Electrostatics
Evolution
Iron
Lithium
Nickel
Voltage
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Summary:A theoretical study of the lithium intercalated LiMSO 4 F and deintercalated MSO 4 F systems, where M = Fe, Co and Ni has been performed within the framework of density functional theory. Beyond predictions of structural evolution and average voltages versus a lithium electrode, we have applied partial density of states and Bader's topological analysis of the electron density to the study of lithium deintercalation. Upon lithium extraction, charge rearrangement occurs for nickel between different d-orbitals, but with little net positive charge gain, while cobalt and iron atoms end up with a clear oxidized state. The participation of oxygen ions in accepting the electron of the lithium is thus enhanced for LiNiSO 4 F. However, this effect does not affect the long-range electrostatic interactions a lot in the lithiated phase, since the valence of all transition metals is very close due to initial lower oxidized state for the Ni atom in the host. It is found that this is not essentially a long-range electrostatic interaction within the lithiated phase but within the host which explains, at least partly, the increase in voltage by passing from Fe to Ni. Our results also shed light upon the possibility of getting an approximate evaluation of the local strain associated with delithiation from the atomic volume evolutions, which are also likely to affect the electrochemical potential. DFT calculations are used to study intercalation features and voltage trends in the LiMSO 4 F (M = Fe, Co, Ni) series.
ISSN:1463-9076
1463-9084
DOI:10.1039/c0cp00517g