Lithium manganese oxyfluoride as a new cathode material exhibiting oxygen redox

House, Robert A.; Jin, Liyu; Maitra, Urmimala; Tsuruta, Kazuki; Somerville, James; Förstermann, Dominic P.; Massel, Felix; Duda, Laurent; Roberts, Matthew; Bruce, Peter G.

doi:10.1039/c7ee03195e

Cited by 189 publications

(292 citation statements)

References 42 publications

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“…Very recently, a manganese system, Li 2 MnO 2 F, has been already reported. The sample delivers a reversible capacity of nearly 300 mA h g −1 , which partly originates from the anionic redox reaction . In addition, it has been reported that Li 2 Mn 2/3 Nb 1/3 O 2 F also delivers a reversible capacity of approximately 300 mA h g −1 in lithium cells on the basis of Mn 2+ /Mn 4+ redox coupled with partial anionic redox …”

Section: Lithium‐excess Metal Oxyfluorides; Lif‐limo2 Systemmentioning

confidence: 96%

Material Design Concept of Lithium‐Excess Electrode Materials with Rocksalt‐Related Structures for Rechargeable Non‐Aqueous Batteries

Yabuuchi

2018

The Chemical Record

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Dependence on lithium‐ion batteries for automobile applications is rapidly increasing, and further improvement, especially for positive electrode materials, is indispensable to increase energy density of lithium‐ion batteries. In the past several years, many new lithium‐excess high‐capacity electrode materials with rocksalt‐related structures have been reported. These materials deliver high reversible capacity with cationic/anionic redox and percolative lithium migration in the oxide/oxyfluoride framework structures, and recent research progresses on these electrode materials are reviewed. Material design strategies for these lithium‐excess electrode materials are also described. Future possibility of high‐energy non‐aqueous batteries with advanced positive electrode materials is discussed for more details.

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Section: Lithium‐excess Metal Oxyfluorides; Lif‐limo2 Systemmentioning

confidence: 96%

Material Design Concept of Lithium‐Excess Electrode Materials with Rocksalt‐Related Structures for Rechargeable Non‐Aqueous Batteries

Yabuuchi

2018

The Chemical Record

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“…[195,196] Another way to mitigate Ol oss is the substitution of F À for O 2À . [197,198] Unlike the well-ordered rock-salt structure,bulk fluorination is possible in the disordered rock-salt structure due to local Li-rich environment. [199] F À doping lowers the average anionic valence thereby the composition can accommodate larger amounts of cationic redox so that the excessive anionic redox could be reduced.…”

Section: Stabilizing the Anionic Redoxmentioning

confidence: 99%

Advances in the Cathode Materials for Lithium Rechargeable Batteries

et al. 2019

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“…Fe-Nb-and Fe-Ti-based DRXs have been reported, but in general show lower discharge energy densities compared with Mn redox systems. [24] The recently reported Li 2 Mn 2/3 Nb 1/3 O 2 F/ Li 2 Mn 1/2 Ti 1/2 O 2 F [5] and Li 1.2 Mn 0.2 V 0.6 O 2 [10] compounds prepared by mechanochemical synthesis rely mainly on Mn 2+ / Mn 4+ redox (for Li 1.2 Mn 0.2 V 0.6 O 2 , V 4+ /V 5+ redox as well) to achieve high capacities over 300 mAh g −1 (room temperature, 20 mA g −1 ). Li 1.3 Mn 0.4 Nb 0.3 O 2 prepared using a traditional solid-state synthesis method exhibits a large initial capacity of >290 mAh g −1 (60 °C, 10 mA g −1 ) based partially on Mn 3+ /Mn 4+ redox in addition to a large amount of oxygen redox, but suffers from substantial capacity fading upon extended cycling.…”

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confidence: 99%

Improved Cycling Performance of Li‐Excess Cation‐Disordered Cathode Materials upon Fluorine Substitution

Lun

Ouyang

Kitchaev

et al. 2018

Advanced Energy Materials

156

241

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research on lithium-ion battery cathodes has been largely dominated by layered rock salt materials in the Li x (Ni-Mn-Co-Al) 2−x O 2 (NMCA) compositional space, [3,4] in which redox activity is limited to Co and Ni. Cobalt in particular is expensive and relatively scarce compared to other 3d transition metals, such as Fe or Mn. [1,3,5] The fact that the cathode structure has to be layered and remain layered upon cycling greatly restricts the changes which can be made to NMCA-type rock salt chemistries.Recent progress in the development of Li percolation theory for rock salt compounds, in which Li transport still takes place even when the cations are disordered, has greatly enlarged the design space for cathode materials. [6,7] Lifting the requirement that cations form an ordered (layered) structure enables the use of various transition metal (TM) redox centers, including Mn 3+ /Mn 4+ , [8,9] Mn 2+ /Mn 4+ , [5,10] Cr 3+ /Cr 5+ , [6,11] Mo 3+ /Mo 6+ , [12] and V 3+ /V 5+ . [11,13] Because these compounds need Li excess to achieve Li percolation, [6,7] they typically also contain high valent charge compensators, such as Nb 5+ , [8,9] Sb 5+ , [14] Mo 6+ , [15,16] and Ti 4+ . [16][17][18] In addition, fluorine substitution is facile inThe recent discovery of Li-excess cation-disordered rock salt cathodes has greatly enlarged the design space of Li-ion cathode materials. Evidence of facile lattice fluorine substitution for oxygen has further provided an important strategy to enhance the cycling performance of this class of materials. Here, a group of Mn 3+ -Nb 5+ -based cation-disordered oxyfluorides, Li 1.2 Mn 3+ 0.6+0.5x Nb 5+ 0.2−0.5x O 2−x F x (x = 0, 0.05, 0.1, 0.15, 0.2) is investigated and it is found that fluorination improves capacity retention in a very significant way. Combining spectroscopic methods and ab initio calculations, it is demonstrated that the increased transition-metal redox (Mn 3+ /Mn 4+ ) capacity that can be accommodated upon fluorination reduces reliance on oxygen redox and leads to less oxygen loss, as evidenced by differential electrochemical mass spectroscopy measurements. Furthermore, it is found that fluorine substitution also decreases the Mn 3+ -induced Jahn-Teller distortion, leading to an orbital rearrangement that further increases the contribution of Mn-redox capacity to the overall capacity.

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Lithium manganese oxyfluoride as a new cathode material exhibiting oxygen redox

Abstract: A new high performance cathode material for Li-ion batteries with a disordered rocksalt structure powered by manganese and oxygen redox.

Cited by 189 publications

References 42 publications

Material Design Concept of Lithium‐Excess Electrode Materials with Rocksalt‐Related Structures for Rechargeable Non‐Aqueous Batteries

Material Design Concept of Lithium‐Excess Electrode Materials with Rocksalt‐Related Structures for Rechargeable Non‐Aqueous Batteries

Advances in the Cathode Materials for Lithium Rechargeable Batteries

Improved Cycling Performance of Li‐Excess Cation‐Disordered Cathode Materials upon Fluorine Substitution

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