Microscale Measurements of the Electrical Conductivity of Doped LiFePO[sub 4]

Chung, Sung‐Yoon; Chiang, Yet‐Ming

doi:10.1149/1.1621289

Cited by 211 publications

(123 citation statements)

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“…The most important member of the family is the iron-based member LiFePO 4 which has been studied extensively. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Despite its numerous advantages, the main drawback of the material is its intrinsically sluggish mass and charge transport. Therefore, various attempts have been made to improve the electrochemical performance of the material.…”

Section: Introductionmentioning

confidence: 99%

Silicon‐Doped LiFePO₄ Single Crystals: Growth, Conductivity Behavior, and Diffusivity

Amin

Lin

Peng

et al. 2009

Adv Funct Materials

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Single crystals of silicon doped LiFePO4 with a silicon content of 1% are grown successfully by the floating zone technique and characterized by single‐crystal and powder X‐ray diffraction, secondary ion mass spectroscopy, and chemical analysis. Electron paramagnetic resonance demonstrates the presence of only Fe2+; no traces of Fe3+ are found. Impedance spectroscopy as well as step‐function polarization/depolarization (DC) measurements are carried out using the cells Ti/LiFe(Si)PO4/Ti and LiAl/LiI/LiFe(Si)PO4/LiI/LiAl. The electronic and ionic conductivities as well as the Li‐diffusivity of the sample in the major crystallographic directions ([h00], [0k0], and [00l]) are determined. Within experimental error the transport properties along the b‐ and c‐axes are found to be the same but differ significantly from the a‐axis, which exhibits lower values. Compared to undoped LiFePO4, Si‐doping leads to an increase of the ionic conductivity while the electronic conductivity decreases, which is in agreement with a donor effect. The activation energies of conductivities and diffusivities are interpreted in terms of defect chemistry and relevant Brouwer diagrams are given.

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Section: Introductionmentioning

confidence: 99%

Silicon‐Doped LiFePO₄ Single Crystals: Growth, Conductivity Behavior, and Diffusivity

Amin

Lin

Peng

et al. 2009

Adv Funct Materials

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“…Charge-discharge profiles and the correspondent dQ/dV vs. voltage plots 3 . Very close position of the oxidation and reduction peaks for pure LVP upon cycling in the 2.5-4.3 V points to low degree of polarization and that the electron and ion transport is facile [17].…”

Section: Methodsmentioning

confidence: 99%

“…Many efforts have been made to turn insulating compounds into attractive electrode materials, including nanosizing, carbon nanopainting and metal doping [1][2][3]. This allows the olivine-type lithium iron phosphate LiFePO 4 with inherent low electronic conductivity and slow lithium diffusion [3,4] to become a promising cathode material exhibiting favorable electrochemical properties and to be commercialized.…”

Section: Introductionmentioning

confidence: 99%

“…This allows the olivine-type lithium iron phosphate LiFePO 4 with inherent low electronic conductivity and slow lithium diffusion [3,4] to become a promising cathode material exhibiting favorable electrochemical properties and to be commercialized. Li ions migration in LiFePO 4 is found to occur preferably down the [010] channels, following a curved trajectory.…”

Section: Introductionmentioning

confidence: 99%

“…According to ab initio simulations of the LiFePO 4 doping, low favorable energies are found only for divalent dopants on the Fe sites, whereas substitution energy for supervalent cations is energetically unfavorable [5]. Meanwhile, it has been № 4 | 2015 Chimica Techno Acta shown experimentally that supervalent doping of LiFePO 4 on Li sites increases its electronic conductivity by a factor of ~108 and results in superior electrochemical performance [3]. Later on, these results were explained by the formation of the conductive impurity phases.…”

Section: Introductionmentioning

confidence: 99%

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Supervalent doping of LiFePO₄ for enhanced electrochemical performance

Косова

Podgornova

2015

Chim.Tech.Acta

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Vanadium and titanium doped orthophosphates LiFe 0.9 M 0.1 PO 4 with an olivinetype structure (space group Pnma) were prepared by mechanochemically assisted solid state synthesis using a high-energy AGO-2 planetary mill and post-annealing at 750 °C. It has been established that the V and Ti ions do not fully substitute for Fe 2+ in the LiFePO 4 structure. The other part of these ions participate in the formation of the secondary phases with the open Nasicon-type structures: monoclinic Li 3 V 2 (PO 4 ) 3 (space group P2 1 /n) and rhombohedral LiTi 2 (PO 4 ) 3 (space group R-3c). According to TEM, the average particle size of the nanocomposites is about 100-300 nm. EDX microanalysis reveals that the small particles of the secondary phases are segregated on the surface of the larger LiFePO 4 particles. On the charge-discharge profiles of LiFe0.9M0.1PO4, the plateaus corresponding to LiFePO 4 and the secondary phases are observed. V doping improves cycleability and rate capability of LiFePO 4 to a greater extent than Ti.

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Direct Physical Imaging and Chemical Probing of LiFePO₄ for Lithium‐Ion Batteries

Chung

Kim

Choi

2010

Adv Funct Materials

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Besides initiating the technological leap that led to the commercial realization of new high-power Li-ion batteries for cordless power tools within only four years after its publication, [ 15 ] the study by Chung et al . [ 12 ] demonstrated and proposed the following scientifi cally important points regarding LiFePO 4 for the fi rst time: 1) Supervalent cations can be doped in the lattice, showing the result of chemical mapping for Nb ions. 2) p -Type bulk electronic conductivity can be remarkably enhanced by doping. 3) A Li-defi cient solid solution phase, Li 1− x FePO 4 , should exist at room temperature, to explain the experimentally observed p -type conduction. 4) Nanoscale particles are easily obtained through simple solid-state synthesis. A number of subsequent results on the aforementioned subjects have been published to data. However, more detailed direct investigations and even new fi ndings, in particular based on experimental evidence rather than incomplete hypothetical calculations, are still needed for a more complete understanding and clarifi cation of LiFePO 4 and other ordered phospho-olivines.Many review papers and book chapters dealing with various syntheses and electrochemical performance are available for both positive and negative electrode systems, including the phosphates in Li batteries. [ 16,17 ] Therefore, in this Feature Article, we focus mainly on the several issues that have been discussed and debated in LiFePO 4 on the basis of materials physics and chemistry. To this end, we provide new results from direct imaging and probing at an atomic scale as well as a brief overview of experimentally signifi cant demonstrations.

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Microscale Measurements of the Electrical Conductivity of Doped LiFePO[sub 4]

Cited by 211 publications

References 4 publications

Silicon‐Doped LiFePO₄ Single Crystals: Growth, Conductivity Behavior, and Diffusivity

Silicon‐Doped LiFePO₄ Single Crystals: Growth, Conductivity Behavior, and Diffusivity

Supervalent doping of LiFePO₄ for enhanced electrochemical performance

Direct Physical Imaging and Chemical Probing of LiFePO₄ for Lithium‐Ion Batteries

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Microscale Measurements of the Electrical Conductivity of Doped LiFePO[sub 4]

Cited by 211 publications

References 4 publications

Silicon‐Doped LiFePO4 Single Crystals: Growth, Conductivity Behavior, and Diffusivity

Silicon‐Doped LiFePO4 Single Crystals: Growth, Conductivity Behavior, and Diffusivity

Supervalent doping of LiFePO4 for enhanced electrochemical performance

Direct Physical Imaging and Chemical Probing of LiFePO4 for Lithium‐Ion Batteries

Contact Info

Product

Resources

About

Silicon‐Doped LiFePO₄ Single Crystals: Growth, Conductivity Behavior, and Diffusivity

Silicon‐Doped LiFePO₄ Single Crystals: Growth, Conductivity Behavior, and Diffusivity

Supervalent doping of LiFePO₄ for enhanced electrochemical performance

Direct Physical Imaging and Chemical Probing of LiFePO₄ for Lithium‐Ion Batteries