Lithium chromium pyrophosphate as an insertion material for Li-ion batteries

Reichardt, Martin; Sallard, Sébastien; Novák, Petr

doi:10.1107/s2052520615017539

Cited by 6 publications

(4 citation statements)

References 22 publications

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“…When the sample is charged to 4.5 V, the absorption edge overlaps with the Cr 2 O 3 reference, which shows that Cr 2+ is oxidized back to Cr 3+ . This indicates that Cr is electrochemically active and that the redox processes for Cr 3+ /Cr 2+ occur in the low-voltage region, consistent with those reported on chromium pyro-, fluoro-, and orthophosphates. − The redox behavior of Cr further substantiates successful Cr substitution into the ε-LiVOPO 4 structure.…”

Section: Results and Discussionsupporting

confidence: 76%

Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO₄

Lee

Siu

Hidalgo

et al. 2021

ACS Appl. Energy Mater.

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Lithium vanadyl phosphate (LiVOPO 4 ) is an attractive cathode material for next-generation lithium-ion batteries, having the ability to reversibly intercalate two Li ions per transition-metal redox center to reach a theoretical capacity of 305 mA h g −1 . This material has a high energy density with two voltage plateaus of 2 and 4 V. However, reduced capacity retention at faster rates and sluggish kinetics in the high-voltage region leave much room for improvement. Cr substitution was implemented to mitigate these limitations and enhance the electrochemical performance of ε-LiVOPO 4 . By various characterization techniques, we have established the composition of the hydrothermally synthesized Cr-substituted samples to be Li x H y Cr z V 1−z OPO 4 solid solution (0.80 ≤ x ≤ 0.85, 0.25 ≤ y ≤ 0.60, and z ≤ 0.05). All Crsubstituted samples demonstrated higher Coulombic efficiency and superior cycling stability for over 40 cycles at C/15. Electrochemical tests show that Cr substitution enhances Li-ion diffusion in the high-voltage regime and the reaction reversibility of ε-LiVOPO 4 .

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Section: Results and Discussionsupporting

confidence: 76%

Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO₄

Lee

Siu

Hidalgo

et al. 2021

ACS Appl. Energy Mater.

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“…The use of chromium seems promising due to its low cost and high stability of Cr 3+ -based phases, which significantly simplifies the synthesis of materials. Though the stability of Cr 3+ , caused by the large octahedral crystal field stabilization energy for 3 d 3 configuration, appears to limit the electrochemical activity of Cr 3+ -containing compounds, − several papers have been published on high-voltage cathodes that operate on the Cr 4+ /Cr 3+ redox transition. − The range of polyanion anode materials based on the Cr 3+ /Cr 2+ couple is even narrower and limited to Li 3 Cr 2 (PO 4 ) 3 , LiCrP 2 O 7 , and NaCr(SO 4 ) 2 . − Surprisingly, despite the wide variety of NASICON-type electrode materials, the Cr 3+ /Cr 2+ redox transition has not been observed within this framework. Based on the above considerations, we have focused on the NaCrNb(PO 4 ) 3 phase previously prepared by Rangan and Gopalakrishnan through the high-temperature ceramic route .…”

Section: Introductionmentioning

confidence: 99%

Realizing Three-Electron Redox Reactions in NASICON-Type NaCrNb(PO₄)₃ for Sodium Ion Battery Applications

Panin,

Cherkashchenko,

Zaitseva

et al. 2024

Chem. Mater.

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Sodium ion battery (SIB) technology offers an attractive alternative to rechargeable batteries in large-scale applications. To meet the practical demands, it is essential to develop stable electrode materials with a high capacity and high energy density. Herein, we demonstrate a successful activation of the Nb 5+ /Nb 4+ , Nb 4+ /Nb 3+ , and Cr 3+ /Cr 2+ redox couples in NASICON-structured NaCrNb(PO 4 ) 3 , thus introducing a novel three-electron reaction anode for sodium ion batteries with a high specific capacity. Carbon-coated NaCrNb(PO 4 ) 3 synthesized using the Pechini sol−gel method demonstrates the reversible capacity of 162 mA h•g −1 at the 1C rate and good cycling stability. This is the first example of NASICON-type anode material with the Cr 3+ /Cr 2+ reversible transition confirmed by Cr K-edge XANES measurements. Operando powder X-ray diffraction showed that sodium insertion−extraction in NaCrNb(PO 4 ) 3 proceeds through a combination of single-phase and biphasic processes. A differential scanning calorimetry study revealed the excellent thermal stability of NaCrNb(PO 4 ) 3 , exceeding that of hard carbon anodes. Attractive electrochemical properties of NaCrNb(PO 4 ) 3 , its high thermal and cyclic stability, and the scalable synthesis of this material demonstrate its potential as an anode for use in sodium ion batteries.

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“…Transition metal diphosphates are of technological interest as possible cathode materials for phosphate-based batteries, as they have strong capabilities for oxidative dehydrogenation. [1][2][3] Iron diphosphates also have been deployed as food additives and pigments. 4 Here, we examine chromium diphosphate (Cr 2 P 2 O 7 ) and iron diphosphate (Fe 2 P 2 O 7 ) under pressure.…”

Section: Introductionmentioning

confidence: 99%

A vibrational study of phase transitions in Fe₂P₂O₇ and Cr₂P₂O₇ under high‐pressures

et al. 2018

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The vibrational properties of synthetic iron diphosphate (Fe2P2O7) and chromium diphosphate (Cr2P2O7) are studied under high‐pressure conditions between ~22 and ~30 GPa, respectively. Each compound's structural response to pressure and pressure‐induced phase transitions are characterized. The chromium‐bearing sample shows coalescence of infrared bands occurring near 6 and 17 GPa: these may be associated with increases in the local symmetry of the P2O7 group. The iron sample undergoes a first‐order phase transition near ~9 GPa, and a possible phase transition near 5.5 GPa. At 9 GPa, the initially single, strong symmetric PO4 stretching mode splits into four modes, and the sole asymmetric PO4 stretching mode splits into two bands. These changes indicate the presence of multiple tetrahedral environments within a larger volume unit cell, and the relative frequencies of the split vibrations indicate a P2O7 environment with a markedly narrowed P–O–P angle. The difference between the behavior of the iron and chromium compounds is probably generated by the smaller iron ion producing a discontinuous decrease in the P–O–P angle at lower pressures than in the analogous chromium compound. Our results demonstrate that the dimerized P2O7 group remains stable under compression to over 20‐30 GPa at 300 K.

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Lithium chromium pyrophosphate as an insertion material for Li-ion batteries

Cited by 6 publications

References 22 publications

Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO₄

Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO₄

Realizing Three-Electron Redox Reactions in NASICON-Type NaCrNb(PO₄)₃ for Sodium Ion Battery Applications

A vibrational study of phase transitions in Fe₂P₂O₇ and Cr₂P₂O₇ under high‐pressures

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Lithium chromium pyrophosphate as an insertion material for Li-ion batteries

Cited by 6 publications

References 22 publications

Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO4

Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO4

Realizing Three-Electron Redox Reactions in NASICON-Type NaCrNb(PO4)3 for Sodium Ion Battery Applications

A vibrational study of phase transitions in Fe2P2O7 and Cr2P2O7 under high‐pressures

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Product

Resources

About

Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO₄

Structure, Composition, and Electrochemistry of Chromium-Substituted ε-LiVOPO₄

Realizing Three-Electron Redox Reactions in NASICON-Type NaCrNb(PO₄)₃ for Sodium Ion Battery Applications

A vibrational study of phase transitions in Fe₂P₂O₇ and Cr₂P₂O₇ under high‐pressures