Local structure in the Li-ion battery cathode material Lix(MnyFe1−y)PO4 for 0&lt;x≤1 and y=0.0, 0.5 and 1.0

Burba, Christopher M.; Frech, Roger

doi:10.1016/j.jpowsour.2007.05.075

Cited by 76 publications

(53 citation statements)

References 58 publications

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“…But poor-rate and low-temperature performance have limited the large-scale application of the cathode material [1,2]. A lot of work has been done in the last 10 years to overcome these drawbacks of LiFePO 4 through material modifications, such as carbon coating, elements doping, and the control of particle size and texture [3][4][5][6][7][8][9]. It was reported that the nano modifications of the material play a major role in improving the cathode performance of cycle life and charge/discharge rate [3,10].…”

Section: Introductionmentioning

confidence: 99%

Enhanced electrochemical performance of LiFePO4 cathode with the addition of fluoroethylene carbonate in electrolyte

Ren

et al. 2012

J Solid State Electrochem

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The effect of the fluoroethylene carbonate (FEC) addition in electrolyte on LiFePO 4 cathode performance was investigated in low-temperature electrolyte LiPF 6 /EC/PC/EMC (0.14/0.18/0.68). Cyclic voltammetry, electrochemical impedance spectroscopy, and charge/discharge tests were conducted in this work. In the presence of FEC, the polarization of LiFePO 4 electrode decreased both at room and low temperatures. Meanwhile, the exchange current density increased. The rate capability of LiFePO 4 electrode was greatly enhanced as well. The morphology of the solid electrolyte interphase (SEI) on LiFePO 4 surface was modified with the addition of FEC as confirmed by scanning electron microscopy measurement. A compact film with small impedance was formed on LiFePO 4 surface compared to the case of FEC-free. The compositions of the film were analyzed by X-ray photoelectron spectroscopic measurement. The contents of Li x PO y F z , LiF, and the carbonate species generated from solvents decomposition were reduced.The modified SEI promoted the migration of lithium ion through the electrode/electrolyte interphase and enhanced the electrochemical performance of the cathode.

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Section: Introductionmentioning

confidence: 99%

Enhanced electrochemical performance of LiFePO4 cathode with the addition of fluoroethylene carbonate in electrolyte

Ren

et al. 2012

J Solid State Electrochem

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“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] Specifically, the prospect of improved energy density over LiFePO 4 due to the higher redox potential of Mn 3+ / Mn 2+ compared to Fe 3+ / Fe 2+ ͓ϳ4.1 V compared to ϳ3.4 V vs Li/ Li + ͑Ref. 16͔͒ has fuelled research into Li͑Fe 1−y Mn y ͒PO 4 .…”

Section: Introductionmentioning

confidence: 99%

“…16͔͒ has fuelled research into Li͑Fe 1−y Mn y ͒PO 4 . 1,3,[5][6][7]11 Several questions in particular arise for mixed cation systems: LiFePO 4 is delithiated in a two-phase reaction forming FePO 4 , and both phases tolerate only a small amount of off-stoichiometry. 17 Zhou et al showed that this two-phase reaction is unusual and driven by the strong electron-Li + interaction.…”

Section: Introductionmentioning

confidence: 99%

Phase diagram and electrochemical properties of mixed olivines from first-principles calculations

2009

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Using first-principles calculations, we study the effect of cation substitution on the transition-metal sublattice in phospho-olivines, with special attention given to the Li x ͑Fe 1−y Mn y ͒PO 4 system. We use a cluster expansion model derived from first-principles with Monte Carlo simulations to calculate finite-T phase diagrams, voltage curves, and solubility limits of the system. The phase diagram of Li x ͑Fe 1−y Mn y ͒PO 4 shows two lowtemperature miscibility gaps separated by a solid solution phase centered at Li composition x Ϸ y, which corresponds to a state where most Fe ions are oxidized and most Mn are not. This intermediate low-T solid solution is stabilized by the dilution of phase-separating interactions caused by the disorder of redox potentials on the transition-metal sites. The calculated voltage curves show two plateaus at ϳ4 -4.2 V and ϳ3.5-3.7 V, corresponding to the Mn 3+ / Mn 2+ and Fe 3+ / Fe 2+ redox couples, respectively, with an extended sloping region in between corresponding to the low-T solid solution phase. In agreement with experiment, we find that the Mn 3+ / Mn 2+ ͑Fe 3+ / Fe 2+ ͒ voltage is decreased ͑increased͒ by Fe ͑Mn͒ substitution. We explain this by considering the energy of the solid solution which is the discharged ͑charged͒ state for these redox couples and argue that such changes are generic to all mixed olivine systems. We also find reduced phase transformation polarization on both plateaus which we attribute to the decreased composition difference between the oxidized and reduced state for each redox couple

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“…This is mainly attributed to its intrinsic low electronic conductivity (∼10 −9 S cm −1 at room temperature [11]) and small Li-ion diffusivity which control the transfer of Li + ions across the LiFePO 4 /FePO 4 interface upon lithium insertion/desertion [12,13]. Such drawback is being overcome by three main approaches, including coatings (such as carbon coating [8][9][10][14][15][16][17][18], ZrO 2 coating [19], TiO 2 coating [20]), heterogeneous doping by metallic elements (such as the partial substitution of Mg, Ti, Cu, Zn, Zr and Nb for Li or Fe of LiFePO 4 [11,13,[21][22][23][24][25][26]) and particle size minimization [15,27,28]. The minimization of the particle size shows a very bright prospect on improving the rate performance of LiFePO 4 at room temperature.…”

Section: Introductionmentioning

confidence: 99%

Influence of AlF3 coating on the electrochemical properties of LiFePO4/graphite Li-ion batteries

Song

Liu

et al. 2009

Journal of Alloys and Compounds

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Local structure in the Li-ion battery cathode material Lix(MnyFe1−y)PO4 for 0<x≤1 and y=0.0, 0.5 and 1.0

Cited by 76 publications

References 58 publications

Enhanced electrochemical performance of LiFePO4 cathode with the addition of fluoroethylene carbonate in electrolyte

Enhanced electrochemical performance of LiFePO4 cathode with the addition of fluoroethylene carbonate in electrolyte

Phase diagram and electrochemical properties of mixed olivines from first-principles calculations

Influence of AlF3 coating on the electrochemical properties of LiFePO4/graphite Li-ion batteries

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