Structural Transformation of LiFePO<sub>4</sub>during Ultrafast Delithiation

Kuß, Christian; Trinh, Ngoc Duc; Andjelic, Stefan; Saulnier, Mathieu; Đufresne, Eric M.; Liang, Guoxian; Schougaard, Steen B.

doi:10.1021/acs.jpclett.7b02569

Cited by 14 publications

(9 citation statements)

References 13 publications

(25 reference statements)

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“…To release the high specific free energy, the twophase boundary of α/β would move forward quickly to become a single phase as α [α/β] with a slightly high Li-ion concentration compared with a normal α phase. Lately, Kuss et al 49 studied the structural transformation of LiFePO 4 nanoparticles during ultrafast delithiation and found an abrupt change of average lattice parameters from the lithium-rich phase to lithium-poor phase, which was consistent with our phase-transition diagram. In contrast, the two-phase boundary of micro-LiFePO 4 would move slowly with a high boundary strain and a low specific free energy, as shown in Figure 8b.…”

Section: Resultsmentioning

confidence: 99%

Size-Dependent Memory Effect of the LiFePO₄ Electrode in Li-Ion Batteries

Guo

Song

et al. 2018

ACS Appl. Mater. Interfaces

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In Li-ion batteries, the phase transition usually determines the electrochemical kinetics of some two-phase electrode materials, and it can be adopted to excellently interpret the memory effect of Li-ion batteries, therefore the size dependence of phase transition was expected to affect the memory effect significantly. In this work, we investigated the memory effect and phase transition of olivine LiFePO4 in Li-ion batteries. Through electrochemical measurements, we found that the memory effect of LiFePO4 was dependent on the particle size, especially after a long-time relaxation. By using the in situ X-ray diffraction, we found that the phase transition of nano-LiFePO4 was ahead of the charging and discharging processes, while it took place concurrently or later for micro-LiFePO4, which might be attributed to the high-specific two-phase boundary of nano-LiFePO4. Furthermore, the phase-transition diagram was adopted to interpret the size-dependent memory effect schematically. Notably, it is the first time to report the phase transition ahead of (dis)charging for nano-LiFePO4, which is significant to understand the phase transition of two-phase electrode materials, as well as the relevant phenomena, such as the memory effect.

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Section: Resultsmentioning

confidence: 99%

Size-Dependent Memory Effect of the LiFePO₄ Electrode in Li-Ion Batteries

Guo

Song

et al. 2018

ACS Appl. Mater. Interfaces

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“…It is also important to consider that for the SMCM measurements, since we are not limited by ionic and electronic transport in the porous electrode, we can reliably enter into high‐speed kinetics. This can be used to test theoretical dynamic models of lithium transport, in a dynamic range not attainable within a normal electrode . Cyclic voltammetry or other potentiodynamic techniques may be initialized from any concentration of Li within the particle, as such, dynamic parameters like apparent diffusion coefficients may be obtained.…”

Section: Resultsmentioning

confidence: 99%

Micropipette Contact Method to Investigate High‐Energy Cathode Materials by using an Ionic Liquid

et al. 2018

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The ionic liquid 1‐ethyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide was used in the scanning micropipette contact method to extend the electrochemical window of the electrolyte solution and enable the study of lithium‐ion battery materials with higher oxidation potential. Localized electrochemical measurements were performed on lithium iron phosphate particles that were drop‐cast onto a glassy carbon substrate. Investigation of the active materials occurred on a small scale (ca. 10 μm diameter), defined by the area of meniscus contact between the electrolyte solution in the micropipette and the substrate. Our studies showed that the SMCM probe is stable and can be used to analyze high energy lithium‐ion battery materials in the range of 2.5 to 5.1 V vs. Li/Li+.

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“…The answer has been given recently owing to the high-rate delithiation reaction of LiFePO 4 with the gaseous oxidant NO 2 , whose reaction free energy corresponds to a charge at about 4.1 V versus Li/Li + [101]. Kuss et al observed the structural changes through in situ synchrotron X-ray diffraction and electronic changes through in situ UV/vis reflectance spectroscopy during the delithiation of LiFePO 4 by this process at high rates, reaching a 100% state of charge in 10 s [102]. The results showed unambiguously that the olivine and heterosite phases still existed, and the phase separation between them macroscopically persists, with a widened solid solution only located along the interface.…”

Section: Structural Changes During Cyclingmentioning

confidence: 99%

Olivine Positive Electrodes for Li-Ion Batteries: Status and Perspectives

Mauger

Julien

2018

Batteries

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Among the compounds of the olivine family, LiMPO 4 with M = Fe, Mn, Ni, or Co, only LiFePO 4 is currently used as the active element of positive electrodes in lithium-ion batteries. However, intensive research devoted to other elements of the family has recently been successful in significantly improving their electrochemical performance, so that some of them are now promising for application in the battery industry and outperform LiFePO 4 in terms of energy density, a key parameter for use in electric vehicles in particular. The purpose of this review is to acknowledge the current state of the art and the progress that has been made recently on all the elements of the family and their solid solutions. We also discuss the results from the perspective of their potential application in the industry of Li-ion batteries.The main disadvantage of olivines with respect to other cathode chemistries for lithium batteries is the lower energy density. This is evidenced in Table 1 where we have reported the gravimetric and volumetric energy densities of LFP and two other cathode materials which have also found a market place in commercial batteries for electric vehicles: the manganese spinel LiMn 2 O 4 , and "LiNiCoAl" (NCA). In terms of energy density, the winner is clearly NCA, the cathode material used by Panasonic to manufacture the batteries of Tesla cars. However, the low energy density of LFP was not an obstacle for its success for EV applications. The top-selling EV manufacturer in the world today is BYD, which makes its own batteries. Its success comes from its choice of the LFP cathode chemistry. As an example, BYD's LFP battery used by e6 taxis in Shenzen has a driving range of 200 km and can be charged to 80% in just 20 min, or 100% in only 40 min using a BYD DC fast charger. The town has 12,000 taxis which will be electric by the end of this year, and all of the 7,000,000 buses are already electric buses, 80% being BYD buses.

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Structural Transformation of LiFePO₄during Ultrafast Delithiation

Cited by 14 publications

References 13 publications

Size-Dependent Memory Effect of the LiFePO₄ Electrode in Li-Ion Batteries

Size-Dependent Memory Effect of the LiFePO₄ Electrode in Li-Ion Batteries

Micropipette Contact Method to Investigate High‐Energy Cathode Materials by using an Ionic Liquid

Olivine Positive Electrodes for Li-Ion Batteries: Status and Perspectives

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Structural Transformation of LiFePO4during Ultrafast Delithiation

Cited by 14 publications

References 13 publications

Size-Dependent Memory Effect of the LiFePO4 Electrode in Li-Ion Batteries

Size-Dependent Memory Effect of the LiFePO4 Electrode in Li-Ion Batteries

Micropipette Contact Method to Investigate High‐Energy Cathode Materials by using an Ionic Liquid

Olivine Positive Electrodes for Li-Ion Batteries: Status and Perspectives

Contact Info

Product

Resources

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Structural Transformation of LiFePO₄during Ultrafast Delithiation

Size-Dependent Memory Effect of the LiFePO₄ Electrode in Li-Ion Batteries

Size-Dependent Memory Effect of the LiFePO₄ Electrode in Li-Ion Batteries