Tailoring a fluorophosphate as a novel 4 V cathode for lithium-ion batteries

Park, Young‐Uk; Seo, Dong‐Hwa; Kim, Byoungkook; Hong, Kun-Pyo; Kim, Hyungsub; Lee, Seongsu; Shakoor, R. A.; Miyasaka, Keiichi; Tarascon, Jean‐Marie; Kang, Kisuk

doi:10.1038/srep00704

Cited by 100 publications

(121 citation statements)

References 52 publications

(104 reference statements)

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“…Experimentally, LiNiPO 4 F discharge voltage is demonstrated to be close to 5.3 V [88]. Khasanova et al [89] have investigated the electrochemical performance and structural properties of the high-voltage cathode material Li 2 CoPO 4 F. The cyclic voltammetry and coulometry under potential step mode in the voltage range 3.0-5.1 V vs. Li revealed a structural transformation at potentials above 4.8 V. This transformation occurring upon Li-extraction appears to be irreversible: the subsequent Li-insertion does not result in restoration of the initial structure, but takes place within a new "modified" framework. According to the structure refinement, this modification involves the mutual rotations of (CoO 4 F 2 ) octahedra and (PO 4 ) tetrahedra accompanied by the considerable unit cell expansion, which is expected to enhance the Li transport upon subsequent cycling.…”

Section: Fepo 4 F (M ¼ Fe Co Ni)mentioning

confidence: 93%

“…The Li 2 MPO 4 F (M ¼ Fe, Co, Mn, Ni) crystallize in three different structures types; triclinic (tavorite) and two-dimensional orthorhombic (Pbcn S.G.) and tunnel-like monoclinic (P2 1 /n S.G.) [85]. In their prior work, Ellis et al [41] [13,42,89]. Dumont Botto et al [85] have pointed out that, contrary to the Na phases which are quite simple to obtain, the synthesis of Li 2 MPO 4 F remains difficult and requires either the ion exchange of the Na-counterparts or a lengthy solid-state reaction (at least 10-h heat treatment) [83].…”

Section: Fepo 4 F (M ¼ Fe Co Ni)mentioning

confidence: 99%

“…Park et al [89] have prepared the Li 1.1 Na 0.4 VPO 4.8 F 0.8 phase from the pseudo-layered structure Na 1.5 VPO 5 F 0.5 using an ion-exchange process between Na + and Li + in 1-hexanol at its boiling point (160 C) under reflux with LiBr as the lithium source. The lattice is made up of VO 5 F octahedral and PO 4 tetrahedra units, where two VO 5 F are linked by a bridging fluorine ion to form V 2 O 10 F bi-octahedron.…”

Section: Other Fluorophosphatesmentioning

confidence: 99%

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Fluoro-polyanionic Compounds

et al. 2016

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During the last decade, numerous studies have been devoted to replace oxides by materials with a polyanion-based framework that are considered as safe alternatives for the traditional oxide electrodes [1] [8,9] have all been considered as thermally stable. All these materials usually exhibit excellent stability on longterm cycling by comparison to lithium metal oxides and essentially no release of oxygen from the lattice or reactivity with the electrolyte. However, the materials were found to be poor electronic conductors [3].The search of new cathode materials aiming to maintain a good mix of properties, with focus on electrochemical and safety parameters, has resulted in the improvement of the electrochemical performance using two strategies: (1) substitution of fluorine for oxygen or (2) fluorine coating of the active particles. As a result, fluorinated compounds display several advantages such as high voltage redox reactions, stabilization of the host lattice, protection the electrode particle surface from HF attack and electrolyte decomposition that impedes a side reaction, and easy transport of mobile Li + ions [10][11][12][13][14][15]. Accordingly, anion substitution is expected as an effective way to enhance the electrochemical performance of spinel and layered compounds, especially for NMC materials [16] due to the strong electronegativity of the F À anion, which will make the structure more stable. Among the metal fluorides as surface fluorination (coating) [20]. While these materials are treated in the first and third chapters, attention hereunder is focussed on technological developments of fluorophosphates and fluorosulfates [21][22][23]. The present chapter gives the state of the art in the understanding of the properties of these F-containing materials. Owing to the progress in

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Section: Fepo 4 F (M ¼ Fe Co Ni)mentioning

confidence: 93%

Section: Fepo 4 F (M ¼ Fe Co Ni)mentioning

confidence: 99%

Section: Other Fluorophosphatesmentioning

confidence: 99%

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Fluoro-polyanionic Compounds

et al. 2016

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“…When y exceeded 0.5, new weak reflections appeared, which could be assigned to other impurity phases such as Na 3 directions for the construction of new high-energy rechargeable batteries. However, the mechanism of alkali ion insertion/deinsertion in these systems is not yet well understood [4,20,21,[24][25][26]. We report here the energy-efficient mechanochemically-assisted solid-state synthesis of sodium vanadium fluorophosphates Na1+yVPO4F1+y (0 ≤ y ≤ 0.75) and the results of the comparative study of their crystal structure and electrochemistry in hybrid-ion cells.…”

Section: Introductionmentioning

confidence: 99%

“…Tetragonal NaVPO 4 F is structurally related to the known Na-ion for the construction of new high-energy rechargeable batteries. However, the mechanism of alkali ion insertion/deinsertion in these systems is not yet well understood [4,20,21,[24][25][26].…”

Section: Introductionmentioning

confidence: 99%

Na1+yVPO4F1+y (0 ≤ y≤ 0.5) as Cathode Materials for Hybrid Na/Li Batteries

Косова

Rezepova

2017

Inorganics

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Using Rietveld-refined X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and electrochemical cycling, it was established that among sodium vanadium fluorophosphate compositions Na 1+y VPO 4 F 1+y (0 ≤ y ≤ 0.75), the single-phase material Na 1.5 VPO 4 F 1.5 or Na 3 V 2 (PO 4 ) 2 F 3 with a tetragonal structure (the P4 2 /mnm S.G.) is formed only for y = 0.5. The samples with y < 0.5 and y > 0.5 possessed different impurity phases. Na 3 V 2 (PO 4 ) 2 F 3 could be considered as a multifunctional cathode material for the fabrication of lithium-ion and sodium-ion high-energy batteries. The reversible discharge capacity of 116 mAh·g −1 was achieved upon cycling Na 3 V 2 (PO 4 ) 2 F 3 in a hybrid Na/Li cell. Decrease in discharge capacity for the other samples was in accordance with the amount of the electrochemically active phase Na 3 V 2 (PO 4 ) 2 F 3 . Na 3 V 2 (PO 4 ) 2 F 3 showed good cycleability and a high rate of performance, presumably due to operation in the mixed Na/Li electrolyte. The study of the structure and composition of charged and discharged samples, and the analysis of differential capacity curves showed a negligible Na/Li electrochemical exchange, and a predominant sodium-based cathode reaction. To increase the degree of the Na/Li electrochemical exchange in Na 3 V 2 (PO 4 ) 2 F 3 , it needs to be desodiated first in a Na cell, and then cycled in a lithium cell. In this case, the electrolyte would be enriched with the Li ions.

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