Elucidation of the surface characteristics and electrochemistry of high-performance LiNiO<sub>2</sub>

Xu, Jun; Lin, Feng; Nordlund, Dennis; Crumlin, Ethan J.; Wang, Feng; Bai, Jianming; Doeff, Marca M.; Tong, Wei

doi:10.1039/c5cc09434h

Cited by 67 publications

(73 citation statements)

References 21 publications

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“…The presence of the latter on the surface of the LNO appears to be unavoidable, as even small amounts of CO 2 react quickly with the layered oxide surface. XPS analysis of samples synthesized under different conditions always revealed some fraction of Li 2 CO 3 on the surface, which is also known to be a cause of capacity decay in NCM and NCA cathodes . Although this is rarely discussed in the literature, washing these cathode materials (and LNO) to remove such residues is often crucial for the electrochemical performance …”

Section: Synthesis Methodsmentioning

confidence: 96%

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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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Section: Synthesis Methodsmentioning

confidence: 96%

“…Recently, Xu et al. also studied the effect of excess Li, and found that a 2 or 10 % Li excess does not make a difference to the bulk LNO structure and its stoichiometry, but that it affects the surface properties of the compound …”

Section: Synthesis Methodsmentioning

confidence: 99%

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

et al. 2019

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“…Even for the pristine sample, however, the average oxidation state of Ni on the surface is somewhat lower than that in the bulk (Δpristine =0.27), as is seen commonly in Ni-rich layered oxides, depending upon their history. 38 In pristine NMC-622, the nominal average oxidation state of Ni is +2.67 (i.e. ; about 2/3 of the Ni is trivalent and 1/3 is divalent), but trivalent Ni is readily reduced, 26 only has a Δ value of 0.14.…”

Section: Soft Xas Resultsmentioning

confidence: 99%

Charge Heterogeneity and Surface Chemistry in Polycrystalline Cathode Materials

Tian

Nordlund

et al. 2018

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Abstract:Nanoscale full-field (FF) transmission X-ray microscopy (TXM) and ensembleaveraged soft X-ray absorption spectroscopy (soft XAS) were used to investigate stateof-charge (SOC) heterogeneities in electrochemically charged or discharged and chemically oxidized samples of LiNi0.6Mn0.2Co0.2O2 cathode materials. We observed considerable and similar non-uniformities in terms of Ni oxidation states (and, by proxy, lithium distributions) for all the samples in the bulk. Therefore, the chemically delithiated samples are similar to the electrochemically charged samples in terms of mesoscale charge heterogeneity in large polycrystalline particle ensembles. However, the gradient oxidation states of transition metals on the surface, which is partly responsible for the electrode degradation mechanism known as surface reconstruction, is much less apparent in chemically delithiated samples. T Response to ReviewersThe previous version of this paper was not sent out for peer review. Response to Reviewers Graphical AbstractClick here to download Graphical Abstract graphicalabstract.tif Charge Heterogeneity and Surface Chemistry in Polycrystalline Cathode Materials SummaryNanoscale full-field (FF) transmission X-ray microscopy (TXM) and ensemble-averaged soft Xray absorption spectroscopy (soft XAS) were used to investigate state-of-charge (SOC) heterogeneities in electrochemically charged or discharged and chemically oxidized samples of LiNi0.6Mn0.2Co0.2O2 cathode materials. We observed considerable and similar non-uniformities in terms of Ni oxidation states (and, by proxy, lithium distributions) for all the samples in the bulk. Therefore, the chemically delithiated samples are similar to the electrochemically charged samples in terms of mesoscale charge heterogeneity in large polycrystalline particle ensembles.However, the gradient oxidation states of transition metals on the surface, which is partly responsible for the electrode degradation mechanism known as surface reconstruction, is much less apparent in chemically delithiated samples.

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“…Ternary or multielement metal oxide nanosheets have also been extensively studied for energy-storage devices, such as NiCo 2 O 4 , [315][316][317][318][319] ZnCo 2 O 4 , [320] Li 4 Ti 5 O 12 , [321][322][323][324][325][326][327][328][329] Co 2 GeO 4 , [330] Zn 2 (OH) 3 VO 3 , [331] LiCoO 2 , [332,333] LiNiO 2 , [334,335] LiMn 2 O 4 , [336] NaTiO 2 , [337] NaCoO 2 , [338,339] NaMnO 2 , [340] Na 0.66 [Li 0.22 Ti 0.78 ] O 2 , [341] and 2D/2D hybrid or heterogeneous metal oxide nanosheets. [342][343][344] For example, NiCo 2 O 4 , with a spinelrelated structure, where Ni occupies the octahedral sites and Co is allocated octa-and tetrahedral sites, delivers high electrical conductivity and a theoretical lithium storage capacity of about 890 mA h g −1 .…”

Section: Othersmentioning

confidence: 99%

Two‐Dimensional Metal Oxide Nanomaterials for Next‐Generation Rechargeable Batteries

et al. 2017

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The exponential increase in research focused on two-dimensional (2D) metal oxides has offered an unprecedented opportunity for their use in energy conversion and storage devices, especially for promising next-generation rechargeable batteries, such as lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs), as well as some post-lithium batteries, including lithium-sulfur batteries, lithium-air batteries, etc. The introduction of well-designed 2D metal oxide nanomaterials into next-generation rechargeable batteries has significantly enhanced the performance of these energy-storage devices by providing higher chemically active interfaces, shortened ion-diffusion lengths, and improved in-plane carrier-/charge-transport kinetics, which have greatly promoted the development of nanotechnology and the practical application of rechargeable batteries. Here, the recent progress in the application of 2D metal oxide nanomaterials in a series of rechargeable LIBs, NIBs, and other post lithium-ion batteries is reviewed relatively comprehensively. Current opportunities and future challenges for the application of 2D nanomaterials in energy-storage devices to achieve high energy density, high power density, stable cyclability, etc. are summarized and outlined. It is believed that the integration of 2D metal oxide nanomaterials in these clean energy devices offers great opportunities to address challenges driven by increasing global energy demands.

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Elucidation of the surface characteristics and electrochemistry of high-performance LiNiO₂

Abstract: Phase pure LiNiO2was prepared using a solid-state method and the optimal synthesis conditions led to a remarkably high capacity of 200 mA h g−1with excellent retention.

Cited by 67 publications

References 21 publications

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

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

Charge Heterogeneity and Surface Chemistry in Polycrystalline Cathode Materials

Two‐Dimensional Metal Oxide Nanomaterials for Next‐Generation Rechargeable Batteries

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Elucidation of the surface characteristics and electrochemistry of high-performance LiNiO2

Abstract: Phase pure LiNiO2was prepared using a solid-state method and the optimal synthesis conditions led to a remarkably high capacity of 200 mA h g−1with excellent retention.

Cited by 67 publications

References 21 publications

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

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

Charge Heterogeneity and Surface Chemistry in Polycrystalline Cathode Materials

Two‐Dimensional Metal Oxide Nanomaterials for Next‐Generation Rechargeable Batteries

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Product

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Elucidation of the surface characteristics and electrochemistry of high-performance LiNiO₂

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

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