Structural and electrochemical studies of a new Tavorite composition: LiVPO<sub>4</sub>OH

Boivin, Édouard; Chotard, Jean‐Noël; Ménétrier, Michel; Bourgeois, Lydie; Bamine, Tahya; Carlier, Dany; Fauth, François; Suard, Emmanuelle; Masquelier, Christian; Croguennec, Laurence

doi:10.1039/c6ta03339c

Cited by 19 publications

(23 citation statements)

References 49 publications

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“…The 19 and 28 ppm peaks are associated with paramagnetic Li environments and may be due to small amounts of defects within the LVPO phase as previously reported. 54…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Performance of Nanosized Disordered LiVOPO₄

Shi¹,

Zhou²,

Seymour

et al. 2018

ACS Omega

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ε-LiVOPO 4 is a promising multielectron cathode material for Li-ion batteries that can accommodate two electrons per vanadium, leading to higher energy densities. However, poor electronic conductivity and low lithium ion diffusivity currently result in low rate capability and poor cycle life. To enhance the electrochemical performance of ε-LiVOPO 4 , in this work, we optimized its solid-state synthesis route using in situ synchrotron X-ray diffraction and applied a combination of high-energy ball-milling with electronically and ionically conductive coatings aiming to improve bulk and surface Li diffusion. We show that high-energy ball-milling, while reducing the particle size also introduces structural disorder, as evidenced by 7 Li and 31 P NMR and X-ray absorption spectroscopy. We also show that a combination of electronically and ionically conductive coatings helps to utilize close to theoretical capacity for ε-LiVOPO 4 at C/50 (1 C = 153 mA h g –1 ) and to enhance rate performance and capacity retention. The optimized ε-LiVOPO 4 /Li 3 VO 4 /acetylene black composite yields the high cycling capacity of 250 mA h g –1 at C/5 for over 70 cycles.

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“…The 19 and 28 ppm peaks are associated with paramagnetic Li environments and may be due to small amounts of defects within the LVPO phase as previously reported. 54…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Performance of Nanosized Disordered LiVOPO₄

Shi¹,

Zhou²,

Seymour

et al. 2018

ACS Omega

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“…Conversely, the antagonist V 5+… O bond along the chains elongates from 2.2 Å in LiVPO 4 O to 2.5 Å in VPO 4 O leading to an unconventional increase in the cell volume during lithium extraction (ΔV/V = 4.1%) [ 63 ]. This VPO 4 O polymorph can also be obtained while deintercalating the homeotype LiVPO 4 OH (and also VPO 4 ·H 2 O), according to an original mechanism [ 64 , 65 ]. Indeed, VPO 4 OH appears instable vs. LiVPO 4 OH and VPO 4 O as this V 4+ -rich phase is not formed upon Li + deintercalation from LiVPO 4 OH.…”

Section: Low Voltage Multi-electron Reactions In Tavorites LImentioning

confidence: 99%

Towards Reversible High-Voltage Multi-Electron Reactions in Alkali-Ion Batteries Using Vanadium Phosphate Positive Electrode Materials

et al. 2021

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Vanadium phosphate positive electrode materials attract great interest in the field of Alkali-ion (Li, Na and K-ion) batteries due to their ability to store several electrons per transition metal. These multi-electron reactions (from V2+ to V5+) combined with the high voltage of corresponding redox couples (e.g., 4.0 V vs. for V3+/V4+ in Na3V2(PO4)2F3) could allow the achievement the 1 kWh/kg milestone at the positive electrode level in Alkali-ion batteries. However, a massive divergence in the voltage reported for the V3+/V4+ and V4+/V5+ redox couples as a function of crystal structure is noticed. Moreover, vanadium phosphates that operate at high V3+/V4+ voltages are usually unable to reversibly exchange several electrons in a narrow enough voltage range. Here, through the review of redox mechanisms and structural evolutions upon electrochemical operation of selected widely studied materials, we identify the crystallographic origin of this trend: the distribution of PO4 groups around vanadium octahedra, that allows or prevents the formation of the vanadyl distortion (O…V4+=O or O…V5+=O). While the vanadyl entity massively lowers the voltage of the V3+/V4+ and V4+/V5+ couples, it considerably improves the reversibility of these redox reactions. Therefore, anionic substitutions, mainly O2− by F−, have been identified as a strategy allowing for combining the beneficial effect of the vanadyl distortion on the reversibility with the high voltage of vanadium redox couples in fluorine rich environments.

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“…The PO 4 stretching region is located between 950 and 1200 cm -1 [24][25][26] . A single crystallographic site exists for phosphorus in LiVPO 4 F, whereas two sites are identified in LiVPO 4 O due to the lower symmetry (i.e.…”

Section: Ftirmentioning

confidence: 99%

Oxidation under Air of Tavorite LiVPO₄F: Influence of Vanadyl-Type Defects on Its Electrochemical Properties

et al. 2016

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Tavorite-type compositions offer a very rich crystal chemistry, among which LiV III PO 4 F has the highest theoretical energy density (i.e. 655 Wh/kg). In this article, an in-depth study of vanadyl-type defects generated by temperature-controlled oxidation of LiV III PO 4 F under air is proposed and their influence on the electrochemical properties are demonstrated. A combination of high resolution synchrotron diffraction, infrared spectroscopy and magic angle spinning nuclear magnetic resonance was used to fully characterize the materials thus generated, from their average long range structure to their local structure with the presence of defects. The increase of the annealing temperature tends to substitute oxygen for fluorine with the formation of a series of LiVPO 4 F 1-x O x compositions. The miscibility domains appear to be narrow at the two ends of the solid solution (i.e. in the composition ranges LiVPO 4 F [1-0.9] O [0-0.1] and LiVPO 4 F [0-0.1] O [1-0.9]). The presence of vanadyl-type defects obtained as localized or more extended ones, depending on the annealing conditions, affects drastically the electrochemical properties of these Tavorite LiVPO 4 F-type materials.

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Structural and electrochemical studies of a new Tavorite composition: LiVPO₄OH

Cited by 19 publications

References 49 publications

Electrochemical Performance of Nanosized Disordered LiVOPO₄

Electrochemical Performance of Nanosized Disordered LiVOPO₄

Towards Reversible High-Voltage Multi-Electron Reactions in Alkali-Ion Batteries Using Vanadium Phosphate Positive Electrode Materials

Oxidation under Air of Tavorite LiVPO₄F: Influence of Vanadyl-Type Defects on Its Electrochemical Properties

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Structural and electrochemical studies of a new Tavorite composition: LiVPO4OH

Cited by 19 publications

References 49 publications

Electrochemical Performance of Nanosized Disordered LiVOPO4

Electrochemical Performance of Nanosized Disordered LiVOPO4

Towards Reversible High-Voltage Multi-Electron Reactions in Alkali-Ion Batteries Using Vanadium Phosphate Positive Electrode Materials

Oxidation under Air of Tavorite LiVPO4F: Influence of Vanadyl-Type Defects on Its Electrochemical Properties

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Structural and electrochemical studies of a new Tavorite composition: LiVPO₄OH

Electrochemical Performance of Nanosized Disordered LiVOPO₄

Electrochemical Performance of Nanosized Disordered LiVOPO₄

Oxidation under Air of Tavorite LiVPO₄F: Influence of Vanadyl-Type Defects on Its Electrochemical Properties