NaMoO<sub>2</sub>: a Layered Oxide with Molybdenum Clusters

Vitoux, Laura; Guignard, Marie; Penin, Nicolas; Carlier, Dany; Darriet, Jacques; Delmas, Claude

doi:10.1021/acs.inorgchem.9b03688

Cited by 9 publications

(9 citation statements)

References 61 publications

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“…Nb is known to form metal−metal bonds in other compounds, including NaNb 10 O 18 64 and NaNb 3 O 5 F, 65 while metal−metal bonds involving Mo have been characterized in NaMoO 2 . 66 The formation of metal−metal dimers to accommodate the charge donated by Li falls into a class of molecular-orbital like redox mechanisms that is increasingly being explored as an alternative to cation-centric redox mechanisms of conventional battery intercalation compounds. 32,67−69 Other compounds exhibiting molecular-orbital redox mechanisms include Na 2 Mn 3 O 7 32 and Li x ScMo 3 O 8 .…”

Section: Discussionmentioning

confidence: 99%

“…Due to the presence of Ti and Nb disorder in Li x TiNb 2 O 7 , in contrast, the metal–metal dimer formation is more localized on individual edge-sharing pairs and therefore, more apparent as a mechanism of redox. Nb is known to form metal–metal bonds in other compounds, including NaNb 10 O 18 and NaNb 3 O 5 F, while metal–metal bonds involving Mo have been characterized in NaMoO 2 …”

Section: Discussionmentioning

confidence: 99%

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Redox Mechanisms, Structural Changes, and Electrochemistry of the Wadsley–Roth Li_xTiNb₂O₇ Electrode Material

Saber,

Behara,

Van der Ven

2023

Chem. Mater.

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The TiNb2O7 Wadsley–Roth phase is a promising anode material for Li-ion batteries, enabling fast cycling and high capacities. While already used in commercial batteries, many fundamental electronic and thermodynamic properties of Li x TiNb2O7 remain poorly understood. We report on an in-depth first-principles study of the redox mechanisms, structural changes, and electrochemical properties of Li x TiNb2O7 as a function of Li concentration. First-principles electronic structure calculations reveal an unconventional redox mechanism upon Li insertion that results in the formation of metal–metal bonds. This metal dimer redox mechanism has important structural consequences as it results in a shortening of cation-pair distances, which in turn affects lattice parameters of the host and thereby alters Li site preferences as the Li concentration is varied. The new insights about redox mechanisms in TiNb2O7 and their effect on the structure and Li site preferences provide guidance on how the electrochemical properties of a promising class of anode materials can be tailored by exploiting the tremendous structural and chemical diversity of Wadsley–Roth phases.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Redox Mechanisms, Structural Changes, and Electrochemistry of the Wadsley–Roth Li_xTiNb₂O₇ Electrode Material

Saber,

Behara,

Van der Ven

2023

Chem. Mater.

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“…60 Recent work on NaMoO 2 showed reversible Na + intercalation. 61 LiScMo 3 O 8 serves as an effective model system for understanding and probing the effects of delocalized redox in Mo cluster compounds. Redox reactions are conventionally postulated to proceed on individual atoms and ions, with some impact from the surrounding environment.…”

Section: ■ Introductionmentioning

confidence: 99%

“…The Chevrel phases M II Mo 6 S 8 , have in contrast, been extensively studied for Mg 2+ , Na + , and Li + batteries . Recent work on NaMoO 2 showed reversible Na + intercalation …”

Section: Introductionmentioning

confidence: 99%

Metal–Metal Bonding as an Electrode Design Principle in the Low-Strain Cluster Compound LiScMo₃O₈

et al. 2022

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Electrode materials for Li + -ion batteries require optimization along several disparate axes related to cost, performance, and sustainability. One of the important performance axes is the ability to retain structural integrity though cycles of charge/discharge. Metal-metal bonding is a distinct feature of some refractory metal oxides that has been largely underutilized in electrochemical energy storage, but that could potentially impact structural integrity. Here LiScMo 3 O 8 , a compound containing triangular clusters of metal-metal bonded Mo atoms, is studied as a potential anode material in Li + -ion batteries. Electrons inserted though lithiation are localized across rigid Mo 3 triangles (rather than on individual metal ions), resulting in minimal structural change as suggested by operando diffraction. The unusual chemical bonding allows this compound to be cycled with Mo atoms below a formally +4 valence state, resulting in an acceptable voltage regime that is appropriate for an anode material.Several characterization methods including potentiometric entropy measurements indicate two-phase regions, which are attributed through extensive first-principles modeling to Li + ordering. This study of LiScMo 3 O 8 provides valuable insights for design principles for structural motifs that stably and reversibly permit Li + (de)insertion.

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“…As a prominent example, electrode materials for rechargeable batteries must allow sufficiently fast diffusion of the charge carrier ions so as not to limit the overall rate capability in an electrochemical cell . Layered transition metal chalcogenides, such as LiTiS 2 , LiCoO 2 , NaCoO 2 , and their analogues, have been explored extensively for battery applications due to their high cation diffusion coefficients and capacities. − Many transition metal chalcogenides also display interesting electronic phases that may be accessed or tuned electrochemically. − Understanding the nature of ion diffusion through the two-dimensional intercalation layers of such materials is critical to engineering their performance but is complicated by subtleties arising from the interplay of chemistry and crystal structure.…”

Section: Introductionmentioning

confidence: 99%

Cation Diffusion Facilitated by Antiphase Boundaries in Layered Intercalation Compounds

Kaufman

Ven

2022

Chem. Mater.

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Facile ion diffusion is critical to the performance of layered intercalation compounds commonly used in battery electrode applications. The diffusion behavior of layered Na and K intercalation compounds is less well understood than that of their Li counterparts and is complicated by the tendency of those ions to order more strongly. Several such materials are predicted to adopt ion-vacancy orderings based on antiphase boundaries (APBs) between ordered domains, with the density of APBs determining the local intercalant concentration. A mechanism for APB migration has been identified in the canonical layered Na intercalation compound P3-Na x CoO 2 , allowing for the collective motion of Na or vacancies through the twodimensional intercalation layers. We report on a kinetic Monte Carlo study examining the macroscopic implications of this APB migration mechanism. We find that the mechanism enables fast long-range diffusion and that the simulated behavior is consistent with Fick's laws. The resulting diffusion coefficients exhibit a significant dependence on Na concentration due to changes in APB density and migration barriers. This study highlights APB migration as a unique transport mechanism, in that it relies on extended defects inherent to the stable phases rather than vacancy cluster defects, which often lead to highly correlated diffusion in related materials.

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NaMoO₂: a Layered Oxide with Molybdenum Clusters

Cited by 9 publications

References 61 publications

Redox Mechanisms, Structural Changes, and Electrochemistry of the Wadsley–Roth Li_xTiNb₂O₇ Electrode Material

Redox Mechanisms, Structural Changes, and Electrochemistry of the Wadsley–Roth Li_xTiNb₂O₇ Electrode Material

Metal–Metal Bonding as an Electrode Design Principle in the Low-Strain Cluster Compound LiScMo₃O₈

Cation Diffusion Facilitated by Antiphase Boundaries in Layered Intercalation Compounds

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NaMoO2: a Layered Oxide with Molybdenum Clusters

Cited by 9 publications

References 61 publications

Redox Mechanisms, Structural Changes, and Electrochemistry of the Wadsley–Roth LixTiNb2O7 Electrode Material

Redox Mechanisms, Structural Changes, and Electrochemistry of the Wadsley–Roth LixTiNb2O7 Electrode Material

Metal–Metal Bonding as an Electrode Design Principle in the Low-Strain Cluster Compound LiScMo3O8

Cation Diffusion Facilitated by Antiphase Boundaries in Layered Intercalation Compounds

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NaMoO₂: a Layered Oxide with Molybdenum Clusters

Redox Mechanisms, Structural Changes, and Electrochemistry of the Wadsley–Roth Li_xTiNb₂O₇ Electrode Material

Redox Mechanisms, Structural Changes, and Electrochemistry of the Wadsley–Roth Li_xTiNb₂O₇ Electrode Material

Metal–Metal Bonding as an Electrode Design Principle in the Low-Strain Cluster Compound LiScMo₃O₈