Phase Change in Li[sub x]FePO[sub 4]

Yamada, Atsuo; Koizumi, Hiroshi; Sonoyama, Noriyuki; Kanno, Ryoji

doi:10.1149/1.1945373

Cited by 236 publications

(208 citation statements)

References 23 publications

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“…The fitting is satisfactory (R wp = 1.28%, R p = 0.98%, R Bragg = 0.559, and GOF = 1.45), and all the Bragg reflections are indexed in orthorhombic lattice parameters of a = 9.8246 (4) ¡, b = 5.7981 (2) ¡, c = 4.7846 (2) ¡, and V = 272.55 (2) ¡ with Pnma symmetry. These values are consistent with the previous result (a = 9.819 ¡, b = 5.792 ¡, c = 4.782 ¡, and V = 272.0 ¡), 21 suggesting successful fabrication of a single FePO 4 phase without impurity.…”

Section: ¹1supporting

confidence: 93%

Electrochemical Properties of Heterosite FePO4 in Aqueous Mg2+ Electrolytes

et al. 2014

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There is currently much interest in advanced energy storage systems because of their potential relevance to power grid storage media. Both earth abundance and high energy density of divalent Mg 2+ ion make Mg batteries attractive as alternatives to Li-ion batteries, but the number of host materials for reversible intercalation is very limited due to the strong coulombic interaction induced in solid matrix. In this work, we report the electrochemical properties of FePO 4 in aqueous Mg 2+ electrolyte. The charge/discharge experiments showed that FePO 4 delivers the first discharge capacity of 90 mAh g −1 with subsequent partial reversibility. The ex-situ Mössbauer spectroscopy confirmed reversible redox of Fe 3+ /Fe 2+ during the discharge and charge processes, while little change was observed in the ex-situ X-ray diffraction patterns. Activation energy for Mg 2+ diffusion in FePO 4 lattice was calculated to over three times larger than that of Li + . It is postulated that the electrochemical reaction of FePO 4 in aqueous Mg 2+ electrolyte proceeds in part by non-topochemical Mg 2+ (de)intercalation accompanied by the irreversible transformation from the crystalline state to the amorphous state in the vicinity of particle surface.

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Section: ¹1supporting

confidence: 93%

Electrochemical Properties of Heterosite FePO4 in Aqueous Mg2+ Electrolytes

et al. 2014

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“…The XRD patterns recorded at the end of the first charge and first discharge are characteristic of single phases, in good agreement with lithium compositions close to x = 0 and x = 1 for Li x FePO 4 and belonging thus to the solid-solution domains observed at the very ends of the charge and discharge processes [19]. Fe 800 -RT-100cycles recovered after a long range cycling at room temperature shows a XRD pattern characteristic of a single-phase, that being a lithium-rich phase (Li 1-ε FePO 4 -type), whereas both Fe 800 -40°C-100cycles and Fe 800 -60°C-40cycles are two-phase mixtures, the main phase being the lithium-rich phase Li 1-ε FePO 4 and the other the lithium-deficient phase Li ε' FePO 4 .…”

Section: X-ray Diffraction Study Of the Materials Recovered After Lonsupporting

confidence: 73%

“…170 mAh/g) [16,17]. The lithium intercalation/deintercalation reaction occurs as a two-phase reaction between a lithium-rich phase (Li 1-ε FePO 4 , ε → 0) and a lithium-deficient phase (Li ε' FePO 4 , ε → 0) at a ~ 3.45 V voltage vs. Li + /Li [2,18], two narrow solidsolution domains being observed at the two ends of the electrochemical process [19].…”

Section: Introductionmentioning

confidence: 99%

Electrochemical performances in temperature for a C-containing LiFePO4 composite synthesized at high temperature

Maccario

Croguennec

Cras

et al. 2008

Journal of Power Sources

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C-LiFePO4 composite was synthesized by mechanochemical activation using iron and lithium phosphates and also cellulose as carbon precursor; this mixture was heated at 800°C under argon during a short time. Long range cyclings at different temperatures (RT, 40°C and 60°C) and at C/20 rate between 2 and 4.5 V vs. Li + /Li were carried out with this C-LiFePO4 composite as positive electrode material in lithium cells. Whatever the cycling conditions used, rather good electrochemical performances were obtained, with a capacity close to the theoretical one and a good cycle life, especially at RT -up to 100 cycles -and at 40°C with ~ 80 % of the initial capacity maintained after 100 cycles. The electrodes recovered after long range cycling were characterized by X-ray diffraction; whatever the cycling temperature no significant structural changes (cell parameters, bond lengths, …) were shown to occur. Nevertheless, iron was found to be present at the negative electrode -as already observed by Amine and co-workers -after long range cycling at 60°C: other analyses have to be done to identify the origin of this iron (from an impurity or from LiFePO4 itself) and to quantify this amount vs. that of active C-LiFePO4 material using larger cells.

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“…A striking feature of LFP is its strong tendency to separate into stable high density and low density phases, indicated by a wide voltage plateau at room temperature [20,26] and other direct experimental evidence [11,27,12,1,19,7]. Similar phase-separation behavior arises in many other intercalation hosts, such as graphite, the typical lithium insertion anode material, which exhibits multiple stable phases.…”

Section: Introductionmentioning

confidence: 83%

Cahn-Hilliard Reaction Model for Isotropic Li-ion Battery Particles

Zeng

Bazant

2013

MRS Proc.

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Using the recently developed Cahn-Hilliard reaction (CHR) theory, we present a simple mathematical model of the transition from solid-solution radial diffusion to two-phase shrinking-core dynamics during ion intercalation in a spherical solid particle. This general approach extends previous Li-ion battery models, which either neglect phase separation or postulate a spherical shrinking-core phase boundary under all conditions, by predicting phase separation only under appropriate circumstances. The effect of the applied current is captured by generalized ButlerVolmer kinetics, formulated in terms of the diffusional chemical potential in the CHR theory. We also consider the effect of surface wetting or de-wetting by intercalated ions, which can lead to shrinking core phenomena with three distinct phase regions. The basic physics are illustrated by different cases, including a simple model of lithium iron phosphate (neglecting crystal anisotropy and coherency strain).

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Phase Change in Li[sub x]FePO[sub 4]

Cited by 236 publications

References 23 publications

Electrochemical Properties of Heterosite FePO4 in Aqueous Mg2+ Electrolytes

Electrochemical Properties of Heterosite FePO4 in Aqueous Mg2+ Electrolytes

Electrochemical performances in temperature for a C-containing LiFePO4 composite synthesized at high temperature

Cahn-Hilliard Reaction Model for Isotropic Li-ion Battery Particles

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