Enabling multi-electron reaction of ε-VOPO<sub>4</sub> to reach theoretical capacity for lithium-ion batteries

Siu, Carrie; Seymour, Ieuan D.; Britto, Sylvia; Zhang, Hanlei; Rana, Jatinkumar; Feng, Jun; Omenya, Fredrick; Zhou, Hui; Chernova, Natasha A.; Zhou, Guangwen; Grey, Clare P.; Piper, Louis F. J.; Whittingham, M. Stanley

doi:10.1039/c8cc02386g

Cited by 52 publications

(65 citation statements)

References 19 publications

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“…[ 12 ] We will show later, that even in the optimized nanocrystalline ε‐VOPO 4 /graphene material, the rate performance is limited by the slower high‐voltage process, which remains one of the major limitations of this material. [ 13 ]…”

Section: Lixvopo4 (X = 0 1) Polymorphism and Stabilitymentioning

confidence: 99%

“…[ 21 ] Further insights into the Li 2 VOPO 4 structure were obtained using nanocrystalline ε‐VOPO 4 as a starting material. [ 13,22 ] In the paper by Siu et al. [ 13 ] we have shown that two Li can be intercalated into ε‐VOPO 4 by comparison of 7 Li NMR spectra obtained by chemical and electrochemical lithiation.…”

Section: Metastable Structures Of Lixvopo4 (X = 15 175 2) Phases:mentioning

confidence: 99%

“…[ 13,22 ] In the paper by Siu et al. [ 13 ] we have shown that two Li can be intercalated into ε‐VOPO 4 by comparison of 7 Li NMR spectra obtained by chemical and electrochemical lithiation. A chemically lithiated ε‐Li 2 VOPO 4 sample was previously investigated by Davis et al.…”

Section: Metastable Structures Of Lixvopo4 (X = 15 175 2) Phases:mentioning

confidence: 99%

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Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

Chernova

Hidalgo

Kaplan

et al. 2020

Advanced Energy Materials

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Vanadyl phosphates comprise a class of multielectron cathode materials capable of cycling two Li+, about 1.66 Na+, and some K+ ions per redox center. In this review, structures, thermodynamic stabilities, and ion diffusion kinetics of various AxVOPO4 (A = Li, Na, K, NH4) polymorphs are discussed. Both the experimental data and first‐principle calculations indicate kinetic limitations for alkali metal ions cycling, especially between for 0 ≤ x ≤ 1, and metastability of phases with x > 1. This creates challenges for multiple‐ion cycling, as the slow kinetics call for nanosized particles, which being metastable and reactive with organic electrolytes are prone to side reactions. Thus, various synthesis approaches, surface coating, and transition metal ion substitution strategies are discussed here as possible ways to stabilize AxVOPO4 structures and improve alkali metal ion diffusion. The role of advanced characterization techniques, such as X‐ray absorption spectroscopy, diffraction, pair distribution function analysis and 7Li and 31P NMR, in understanding the reaction mechanism from both structural and electronic points of view is emphasized.

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Section: Lixvopo4 (X = 0 1) Polymorphism and Stabilitymentioning

confidence: 99%

Section: Metastable Structures Of Lixvopo4 (X = 15 175 2) Phases:mentioning

confidence: 99%

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Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

Chernova

Hidalgo

Kaplan

et al. 2020

Advanced Energy Materials

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“…ε-VOPO4 investigated in the present study was prepared by hydrothermal synthesis. 43 Thin laminates for XAS investigation were prepared by mixing ε-VOPO4 powder with graphene and polyvinylidene fluorine (PVDF) as binder in a weight ratio 75:15:10 using 1-methyl-2pyrrolidinine (NMP) as the solvent. The resultant slurry was tape cast onto an aluminum foil and dried in air at 60 °C.…”

Section: Iib Sample Preparation Detailsmentioning

confidence: 99%

An improved laboratory-based x-ray absorption fine structure and x-ray emission spectrometer for analytical applications in materials chemistry research

Jahrman

Holden

Ditter

et al. 2019

Review of Scientific Instruments

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X-ray absorption fine structure (XAFS) and x-ray emission spectroscopy (XES) are advanced xray spectroscopies that impact a wide range of disciplines. However, unlike the majority of other spectroscopic methods, XAFS and XES are accompanied by an unusual access model, wherein; the dominant use of the technique is for premier research studies at world-class facilities, i.e., synchrotron x-ray light sources. In this paper we report the design and performance of an improved spectrometer XAFS and XES based on the general conceptual design of Seidler, et al., Rev. Sci. Instrum. 2014. New developments include reduced mechanical degrees of freedom, much-increased flux, and a wider Bragg angle range to enable extended x-ray absorption fine structure (EXAFS) for the first time with this type of modern laboratory XAFS configuration. This instrument enables a new class of routine applications that are incompatible with the mission and access model of the synchrotron light sources. To illustrate this, we provide numerous examples of x-ray absorption near edge structure (XANES), EXAFS, and XES results for a variety of problems and energy ranges. Highlights include XAFS and XES measurements of battery electrode materials, EXAFS of Ni and V with full modeling of results to validate monochromator performance, valence-to-core XES for 3d transition metal compounds, and uranium XANES and XES for different oxidation states. Taken en masse, these results further support the growing perspective that modern laboratory-based XAFS and XES have the potential to develop a new branch of analytical chemistry.

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“…The ε‐VOPO 4 system is considered to be one of the most promising electrodes to provide 2‐e reactions. The theoretical 2‐e capacity has been achieved by controlling the morphology and particle size of ε‐VOPO 4 until the most recent . In addition, three forms of VOPO 4 can add one Na + ion to form three NaVOPO 4 polymorphisms .…”

Section: Vanadium‐based Polyanionic Compoundsmentioning

confidence: 99%

Research Progress in Multielectron Reactions in Polyanionic Materials for Sodium‐Ion Batteries

Liang

Gong

et al. 2018

Small Methods

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www.advancedsciencenews.com www.small-methods.com and Co). The opportunities and critical issues in this interesting field have also been proposed and discussed for further investigations. Vanadium-Based Polyanionic CompoundsThe versatile coordinations and oxidation states of V ions enable V-containing polyanionic compositions extreme structural diversity. [22] In addition, multiple oxidation states of V (+2 -+5) in these structures might be accessed in a common voltage range (0-4.5 V). [23] These make V-based polyanionic compounds highly suitable for the realization of multielectron reactions. NASICON-Na 3 V 2 (PO 4 ) 3Na 3 V 2 (PO 4 ) 3 adopts a well-known NASICON structure that has rhombohedral phase with high-temperature R-3c symmetry and monoclinic phase with low-temperature C2/c symmetry resulting from Na-vacancy order/disorder. [24,25] Typically, the NASICON framework is built from V 2 (PO 4 ) 3 "lantern units" constructed by corner-sharing VO 6 octahedra and PO 4 tetrahedra. There are two Na sites: 6b Na(1) sites that locate between two adjacent V 2 (PO 4 ) 3 lantern units and 18e Na(2) sites that situate between two PO 4 tetrahedra, allowing multiple Na extraction and insertion and a 3D Na diffusion channel (Figure 2d). [25,26] NASICON-type materials show extremely versatile compounds like so on. Chen et al. and Jian et al. have published excellent reviews on NASICON-structured materials for energy storage. [34,35] Here, we mainly focus on the multielectron reactions of these materials. Na 3 V 2 (PO 4 ) 3 shows promising electrochemical performances: moderate voltage (3.4 V), decent capacity (117 mAh g −1 ), ultralong cycling life, and excellent rate performance due to robust structure and fast Na + ion transport in NASICON framework. [34] This compound attracts extensive attentions as one of the most promising cathode materials for SIBs. [24,26,30,31,[36][37][38][39][40][41][42][43][44][45][46][47][48] Accessibility of the Third NaThe electrochemical extraction of Na + would result in NaV 2 (PO 4 ) 3 via a two-phase reaction, which is a 1-e reaction per V ion. [38] X-ray absorption near edge structure (XANES) further proved that the valence of vanadium ion is +4 after charging to 4.0 V. [36] However, the third Na + ion in Na 3 V 2 (PO 4 ) 3 is inaccessible even charging the electrode up to 4.6 V (Figure 1a). [48] Recently, Jian et al. have determined that all Na + ions at Na(2) sites can be extracted while those at Na(1) maintain in their positions during chemical oxidation using the NO 2 BF 4 as the oxidant. [37] The seemingly impossible extraction of Na + toward V 2 (PO 4 ) 3 recalls a result reported nearly 30 years ago. [49] All the Na + ions have been chemically extracted from Na 3 V 2 (PO 4 ) 3 using Cl 2 as the oxidant to yield a V 2 (PO 4 ) 3 . It is surprising that NO 2 BF 4 cannot oxidize Na 3 V 2 (PO 4 ) 3 to V 2 (PO 4 ) 3 , since the redox potential of the NO 2 + /NO 2 redox (4.8 V) is much higher than that of the Cl 2 /Cl − redox (4.1 V) although the later one is estimated in the aqueous s...

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Enabling multi-electron reaction of ε-VOPO₄ to reach theoretical capacity for lithium-ion batteries

Abstract: By controlling the morphology and particle size of the epsilon polymorph of vanadyl phosphate, ε-VOPO4, it can fully reversibly intercalate two Li-ions and reach the theoretical capacity of 305 mA h g-1 over two voltage plateaus at about 4.0 and 2.5 V.

Cited by 52 publications

References 19 publications

Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

An improved laboratory-based x-ray absorption fine structure and x-ray emission spectrometer for analytical applications in materials chemistry research

Research Progress in Multielectron Reactions in Polyanionic Materials for Sodium‐Ion Batteries

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Enabling multi-electron reaction of ε-VOPO4 to reach theoretical capacity for lithium-ion batteries

Abstract: By controlling the morphology and particle size of the epsilon polymorph of vanadyl phosphate, ε-VOPO4, it can fully reversibly intercalate two Li-ions and reach the theoretical capacity of 305 mA h g-1 over two voltage plateaus at about 4.0 and 2.5 V.

Cited by 52 publications

References 19 publications

Vanadyl Phosphates AxVOPO4 (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

Vanadyl Phosphates AxVOPO4 (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

An improved laboratory-based x-ray absorption fine structure and x-ray emission spectrometer for analytical applications in materials chemistry research

Research Progress in Multielectron Reactions in Polyanionic Materials for Sodium‐Ion Batteries

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Resources

About

Enabling multi-electron reaction of ε-VOPO₄ to reach theoretical capacity for lithium-ion batteries

Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries

Vanadyl Phosphates A_xVOPO₄ (A = Li, Na, K) as Multielectron Cathodes for Alkali‐Ion Batteries