Electronic-Structure Origin of Cation Disorder in Transition-Metal Oxides

Urban, Alexander; Abdellahi, Aziz; Dacek, Stephen; Artrith, Nongnuch; Ceder, Gerbrand

doi:10.1103/physrevlett.119.176402

Cited by 150 publications

(137 citation statements)

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“…[25] By systemically varying the fluorine content, we show that capacity and cyclability can be improved by fluorination, but that a trade-off exists with higher fluorination, generally leading to more stable materials with less capacity loss even as total energy density decreases once an optimal F content is reached. A compound with x = 0.2, "LMF20," was also synthesized as an example where the F solubility limit is exceeded).…”

mentioning

confidence: 87%

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

Lun

Ouyang

Kitchaev

et al. 2018

Advanced Energy Materials

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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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mentioning

confidence: 87%

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

Lun

Ouyang

Kitchaev

et al. 2018

Advanced Energy Materials

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153

241

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“…All the disordered rock salt cathodes reported so far indeed contain elements such as Mo 6+ , Cr 6+ , V 5+ , Nb 5+ , Ti 4+ , or Zr 4+ not only as charge compensators, but also because a cation with a d 0 electronic configuration is needed to stabilize the structure . Transition metals with a d 0 configuration are least sensitive with respect to local site distortions and can tolerate them at very low energy cost.…”

Section: Future Prospectsmentioning

confidence: 99%

There and Back Again—The Journey of LiNiO₂ as a Cathode Active Material

et al. 2019

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This Review provides a comprehensive overview of LiNiO2 (LNO), almost 30 years after its introduction as a cathode active material. We aim to highlight the physicochemical peculiarities that make LNO a complex material in every aspect. We specifically stress the effect of the Li off‐stoichiometry (Li1−zNi1+zO2) on every property of LNO, especially the electrochemical ones. The key instability issues that plague the compound and the strategies that have been implemented so far to overcome them are discussed in detail. Finally, the open questions that remain to be addressed by the scientific community are summarized, and the research directions that seem the most promising to enable LNO to be fully exploited are elucidated.

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“…Alle bisher beschriebenen ungeordneten Steinsalzkathoden enthalten tatsächlich Elemente wie Mo 6+ , Cr 6+ , V 5+ , Nb 5+ , Ti 4+ oder Zr 4+ nicht nur als Ladungskompensatoren, sondern auch, weil zur Stabilisierung der Struktur ein Kation mit d 0 ‐Elektronenkonfiguration benötigt wird . Übergangsmetalle mit d 0 ‐Konfiguration sind gegenüber lokalen Verzerrungen am wenigsten empfindlich und können diese unter sehr niedrigem Energieaufwand tolerieren.…”

Section: Zukunftsaussichtenunclassified

Hin und zurück – die Entwicklung von LiNiO₂ als Kathodenaktivmaterial

et al. 2019

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Wir geben in diesem Aufsatz einen umfassenden Überblick über LiNiO2 (LNO), fast 30 Jahre nach seiner ursprünglichen Einführung als Kathodenaktivmaterial. Ziel ist es, diejenigen physikalisch‐chemischen Eigenschaften hervorzuheben, die LNO in jeder Hinsicht zu einem komplexen Material machen. Der Effekt der Lithium‐Nichtstöchiometrie (Li1−zNi1+zO2) spielt hierbei eine wichtige Rolle. Sie beeinflusst jede Eigenschaft von LNO, besonders das elektrochemische Verhalten. Die wichtigsten Instabilitätsprobleme, die das Material beeinträchtigen, und die Strategien, die bislang implementiert wurden, um diese Probleme zu lösen, werden im Detail diskutiert. Schließlich werden die wichtigsten offenen Fragen, die vor einer nachhaltigen Nutzung von LNO noch zu klären sind, zusammengefasst, und es wird erläutert, welche Forschungsrichtungen vielversprechend sind, um das volle Potential von LNO zu nutzen.

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Electronic-Structure Origin of Cation Disorder in Transition-Metal Oxides

Cited by 150 publications

References 52 publications

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

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

There and Back Again—The Journey of LiNiO₂ as a Cathode Active Material

Hin und zurück – die Entwicklung von LiNiO₂ als Kathodenaktivmaterial

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Electronic-Structure Origin of Cation Disorder in Transition-Metal Oxides

Cited by 150 publications

References 52 publications

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

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

There and Back Again—The Journey of LiNiO2 as a Cathode Active Material

Hin und zurück – die Entwicklung von LiNiO2 als Kathodenaktivmaterial

Contact Info

Product

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There and Back Again—The Journey of LiNiO₂ as a Cathode Active Material

Hin und zurück – die Entwicklung von LiNiO₂ als Kathodenaktivmaterial