The layered intercalation compounds Li(Mn1-yCoy)Oz: positive electrode materials for lithium-ion batteries

A. Robert Armstrong, Alastair D. Robertson, Robert Gitzendanner, Peter G. Bruce*

*Corresponding author for this work

Research output: Contribution to journalArticle

84 Citations (Scopus)

Abstract

The layered intercalation compounds Li(Mn1-yCoy)O2; 0 ≤ y ≤ 0.5 cannot be prepared by conventional solid state reaction but have been synthesized using a solution-based route coupled with ion exchange. A continuous range of solid solutions with rhombohedral symmetry exists for 0.1 ≤ y ≤ 0.5. Consideration of transition metal to oxygen bond lengths indicates that Mn3+ is replaced by cobalt in the trivalent state. Localized high spin Mn3+ (3d4) induces a cooperative Jahn-Teller distortion in layered LiMnO2, lowering the symmetry from rhombohedral R3̄m to monoclinic (C2/m). Substitution of as little as 10% Mn by Co is sufficient to suppress the distortion in Li0.9(Mn0.9Co0.1)O2, whereas half the Li must be extracted from LiMnO2 to achieve a single undistorted rhombohedral phase. On removing and reinserting Li in LiMnO2 only half the quantity of Li (equivalent to a specific charge of 130 mAhg-1) may be reinserted on the first cycle; this substantial drop in capacity is eliminated with only 10% Co substitution. The latter material can sustain a large capacity on cycling (200 mAhg-1). Higher Co contents have somewhat lower capacities but fade less at higher cycle numbers. The marked improvement in capacity retention of the Co-doped materials compared with pure LiMnO2 may be related in part to the absence of the Jahn-Teller distortion. Electrochemical data indicate conversion to a spinel-like structure on cycling. Such conversion is progressively slower with increasing Co content. Cycling of this spinel-like material is significantly better than Co-doped spinel of the same composition. These materials are of interest as electrodes in rechargeable lithium batteries.

Original languageEnglish
Pages (from-to)549-556
Number of pages8
JournalJournal of Solid State Chemistry
Volume145
Issue number2
DOIs
Publication statusPublished - Jul 1999
Externally publishedYes

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Intercalation compounds
electrode materials
intercalation
electric batteries
lithium
Jahn-Teller effect
cycles
Electrodes
spinel
ions
Substitution reactions
Lithium batteries
substitutes
Bond length
Cobalt
Solid state reactions
lithium batteries
Transition metals
symmetry
Solid solutions

Cite this

@article{6541304692ce4ce0a43d689e9b614856,
title = "The layered intercalation compounds Li(Mn1-yCoy)Oz: positive electrode materials for lithium-ion batteries",
abstract = "The layered intercalation compounds Li(Mn1-yCoy)O2; 0 ≤ y ≤ 0.5 cannot be prepared by conventional solid state reaction but have been synthesized using a solution-based route coupled with ion exchange. A continuous range of solid solutions with rhombohedral symmetry exists for 0.1 ≤ y ≤ 0.5. Consideration of transition metal to oxygen bond lengths indicates that Mn3+ is replaced by cobalt in the trivalent state. Localized high spin Mn3+ (3d4) induces a cooperative Jahn-Teller distortion in layered LiMnO2, lowering the symmetry from rhombohedral R3̄m to monoclinic (C2/m). Substitution of as little as 10{\%} Mn by Co is sufficient to suppress the distortion in Li0.9(Mn0.9Co0.1)O2, whereas half the Li must be extracted from LiMnO2 to achieve a single undistorted rhombohedral phase. On removing and reinserting Li in LiMnO2 only half the quantity of Li (equivalent to a specific charge of 130 mAhg-1) may be reinserted on the first cycle; this substantial drop in capacity is eliminated with only 10{\%} Co substitution. The latter material can sustain a large capacity on cycling (200 mAhg-1). Higher Co contents have somewhat lower capacities but fade less at higher cycle numbers. The marked improvement in capacity retention of the Co-doped materials compared with pure LiMnO2 may be related in part to the absence of the Jahn-Teller distortion. Electrochemical data indicate conversion to a spinel-like structure on cycling. Such conversion is progressively slower with increasing Co content. Cycling of this spinel-like material is significantly better than Co-doped spinel of the same composition. These materials are of interest as electrodes in rechargeable lithium batteries.",
author = "Armstrong, {A. Robert} and Robertson, {Alastair D.} and Robert Gitzendanner and Bruce, {Peter G.}",
year = "1999",
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journal = "Journal of Solid State Chemistry",
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The layered intercalation compounds Li(Mn1-yCoy)Oz : positive electrode materials for lithium-ion batteries. / Armstrong, A. Robert; Robertson, Alastair D.; Gitzendanner, Robert; Bruce, Peter G.

In: Journal of Solid State Chemistry, Vol. 145, No. 2, 07.1999, p. 549-556.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The layered intercalation compounds Li(Mn1-yCoy)Oz

T2 - positive electrode materials for lithium-ion batteries

AU - Armstrong, A. Robert

AU - Robertson, Alastair D.

AU - Gitzendanner, Robert

AU - Bruce, Peter G.

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N2 - The layered intercalation compounds Li(Mn1-yCoy)O2; 0 ≤ y ≤ 0.5 cannot be prepared by conventional solid state reaction but have been synthesized using a solution-based route coupled with ion exchange. A continuous range of solid solutions with rhombohedral symmetry exists for 0.1 ≤ y ≤ 0.5. Consideration of transition metal to oxygen bond lengths indicates that Mn3+ is replaced by cobalt in the trivalent state. Localized high spin Mn3+ (3d4) induces a cooperative Jahn-Teller distortion in layered LiMnO2, lowering the symmetry from rhombohedral R3̄m to monoclinic (C2/m). Substitution of as little as 10% Mn by Co is sufficient to suppress the distortion in Li0.9(Mn0.9Co0.1)O2, whereas half the Li must be extracted from LiMnO2 to achieve a single undistorted rhombohedral phase. On removing and reinserting Li in LiMnO2 only half the quantity of Li (equivalent to a specific charge of 130 mAhg-1) may be reinserted on the first cycle; this substantial drop in capacity is eliminated with only 10% Co substitution. The latter material can sustain a large capacity on cycling (200 mAhg-1). Higher Co contents have somewhat lower capacities but fade less at higher cycle numbers. The marked improvement in capacity retention of the Co-doped materials compared with pure LiMnO2 may be related in part to the absence of the Jahn-Teller distortion. Electrochemical data indicate conversion to a spinel-like structure on cycling. Such conversion is progressively slower with increasing Co content. Cycling of this spinel-like material is significantly better than Co-doped spinel of the same composition. These materials are of interest as electrodes in rechargeable lithium batteries.

AB - The layered intercalation compounds Li(Mn1-yCoy)O2; 0 ≤ y ≤ 0.5 cannot be prepared by conventional solid state reaction but have been synthesized using a solution-based route coupled with ion exchange. A continuous range of solid solutions with rhombohedral symmetry exists for 0.1 ≤ y ≤ 0.5. Consideration of transition metal to oxygen bond lengths indicates that Mn3+ is replaced by cobalt in the trivalent state. Localized high spin Mn3+ (3d4) induces a cooperative Jahn-Teller distortion in layered LiMnO2, lowering the symmetry from rhombohedral R3̄m to monoclinic (C2/m). Substitution of as little as 10% Mn by Co is sufficient to suppress the distortion in Li0.9(Mn0.9Co0.1)O2, whereas half the Li must be extracted from LiMnO2 to achieve a single undistorted rhombohedral phase. On removing and reinserting Li in LiMnO2 only half the quantity of Li (equivalent to a specific charge of 130 mAhg-1) may be reinserted on the first cycle; this substantial drop in capacity is eliminated with only 10% Co substitution. The latter material can sustain a large capacity on cycling (200 mAhg-1). Higher Co contents have somewhat lower capacities but fade less at higher cycle numbers. The marked improvement in capacity retention of the Co-doped materials compared with pure LiMnO2 may be related in part to the absence of the Jahn-Teller distortion. Electrochemical data indicate conversion to a spinel-like structure on cycling. Such conversion is progressively slower with increasing Co content. Cycling of this spinel-like material is significantly better than Co-doped spinel of the same composition. These materials are of interest as electrodes in rechargeable lithium batteries.

U2 - 10.1006/jssc.1999.8216

DO - 10.1006/jssc.1999.8216

M3 - Article

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SP - 549

EP - 556

JO - Journal of Solid State Chemistry

JF - Journal of Solid State Chemistry

SN - 0022-4596

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