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Jiang, Tonghu; Falk, Michael L.

doi:10.1103/physrevb.85.245111

Cited by 36 publications

(50 citation statements)

References 78 publications

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“…The LVO500 cell was discharged to 1.8 V vs. Li/Li + and charged to 3.8 V at a current rate of C/18 (20.2 mA/g) on a Maccor cycle life tester while the EDXRD patterns were continuously collected. During lithiation 9 scans were taken (scans 1-9), at average equivalences (x in Li x V 3 O 8 ): x = 1.1, 1.5, 1.8, 2.0, 2.3, 2.6, 2.9, 3.2, and 3.5; during delithiation 10 scans were taken (scans [11][12][13][14][15][16][17][18][19][20], at average equivalences x = 3.6, 3.3, 3.0, 2.7, 2.3, 2.1, 1.8, 1.5, 1.3, and 1.2. Figure 2 is a schematic of the set-up used for the operando EDXRD measurements.…”

Section: Methodsmentioning

confidence: 99%

“…1,4 Phase transitions during battery operation are significant because they have implications for electrochemical performance, rate capability, as well as cycle life. Previous studies have interrogated phase change using a variety of methods, both experimental and theoretical: electrochemical, [5][6][7] in-situ 8,9 and ex-situ 10 characterization (SEM, 7,11 XRD 4,5,7,10,11 ), DFT, 9,12 and continuum modeling. 6 Electrochemical measurements are commonly used to investigate battery performance.…”

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confidence: 99%

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Operando Study of LiV₃O₈Cathode: Coupling EDXRD Measurements to Simulations

Brady

Zhang

Bruck

et al. 2018

J. Electrochem. Soc.

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The electrochemical and phase-change behavior of lithium trivanadate during lithiation and delithiation is analyzed by comparing a coupled electrode/crystal-scale mathematical model to operando experiments. The model expands on a previously published crystalscale model by adding descriptions for electrode-scale resistances. Agreement between simulated and observed electrochemical measurements is compelling. Time and space-resolved operando EDXRD measurements on the cathode are compared with simulated concentration profiles. Both simulation and experiment reveal that during lithiation, phase transformations preferentially occur near the separator, while during delithiation the disappearance of the lithium-rich β-phase occurs uniformly across the electrode. Lithium trivanadate, LiV 3 O 8 , and transition metal oxides in general are attractive cathode materials for lithium-ion batteries due to their moderate redox potential, high theoretical capacity, and good rate capability.1,2 LiV 3 O 8 , as with many other transition metal oxides, undergoes phase change during lithiation. 1,3,4 Up to a composition of Li 2.5 V 3 O 8 , the material is in the parent layered α-phase; from Li 2.5 V 3 O 8 to Li 4 V 3 O 8 , the α-to β-phase transition process takes place where the layered phase transforms into the defected rock-salt β-phase; beyond Li 4 V 3 O 8 , lithiation occurs into the single β-phase. 1,4Phase transitions during battery operation are significant because they have implications for electrochemical performance, rate capability, as well as cycle life. Previous studies have interrogated phase change using a variety of methods, both experimental and theoretical: electrochemical, 5-7 in-situ 8,9 and ex-situ 10 characterization (SEM,7,11 XRD 4,5,7,10,11 ), DFT, 9,12 and continuum modeling. 6Electrochemical measurements are commonly used to investigate battery performance. While these measurements are useful, they are indirect measurements of the physical processes that govern performance. For this reason, direct measurements through characterization, such as SEM, XRD, and TEM are used in-situ and ex-situ to try to understand the internal processes. However, because battery systems are highly dynamic, if there are even short delays between operating the battery and interrogating it, the observed profiles may not be indicative of the profiles that exist during operation. This concept is illustrated in Figure 1. Using the parameters listed in Table II and discharging at C/18 until an equivalence of Li 2.4 V 3 O 8 , simulations show that even with a short gap between discharge and characterization (two hours) the spatial profiles change significantly. And if there is a 10-hour delay or more, the non-uniformities present during operation will be completely undetectable. operando studies are therefore very valuable because they allow for characterization in time and position and show how these profiles evolve during battery operation; insights about the physical process can be gained from this characterization information. Z...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Operando Study of LiV₃O₈Cathode: Coupling EDXRD Measurements to Simulations

Brady

Zhang

Bruck

et al. 2018

J. Electrochem. Soc.

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“…Additionally, DFT calculations indicate that the saturation composition in the α-phase is Li 2.5 V 3 O 8 . 27 In summary, experiments, theoretical calculations, and this continuum model all suggest the saturation composition in the α-phase is Li 2.5 V 3 O 8 .…”

Section: Parameter Estimationmentioning

confidence: 99%

Discharge, Relaxation, and Charge Model for the Lithium Trivanadate Electrode: Reactions, Phase Change, and Transport

Brady

Zhang

Knehr

et al. 2016

J. Electrochem. Soc.

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The electrochemical behavior of lithium trivanadate (LiV 3 O 8 ) during lithiation, delithiation, and voltage recovery experiments is simulated using a crystal-scale model that accounts for solid-state diffusion, charge-transfer kinetics, and phase transformations. The kinetic expression for phase change was modeled using an approach inspired by the Avrami formulation for nucleation and growth. Numerical results indicate that the solid-state diffusion coefficient of lithium in LiV 3 O 8 is ∼10 −13 cm 2 s −1 and the equilibrium compositions in the two phase region (∼2.5 V) are Li 2.5 V 3 O 8 :Li 4 V 3 O 8 . Agreement between the simulated and experimental results is excellent. Relative to the lithiation curves, the experimental delithiation curves show significantly less overpotential at low levels of lithiation (end of charge). Simulations are only able to capture this result by assuming that the solid-state mass-transfer resistance is less during delithiation. The proposed rationale for this difference is that the (100) face is inactive during lithiation, but active during delithiation. Finally, by assuming non-instantaneous phase-change kinetics, estimates are made for the overpotential due to imperfect phase change (supersaturation). Large scale transportation and stationary applications of lithium ion batteries require inexpensive, reliable, and safe systems.1 Transition metal (cobalt, iron, nickel, manganese, vanadium, titanium, tungsten, and molybdenum) oxides are attractive lithium intercalation cathode materials for these applications because of their natural abundance and high redox potentials.2 Conventional anode materials, such as graphite, typically have higher specific capacities than cathode materials, such as LiCoO 2 and LiFePO 4 . This difference in capacity is because typical cathode materials can only accept one lithium per formula unit; therefore, there is a potential breakthrough in developing cathode materials that are able to host lithium-ions in excess of one per formula unit. For example, LiV 3 O 8 is an attractive material because of its high potential suitable for battery applications (∼3 V) and high theoretical specific energy (∼374 mAh g −1 ). [3][4][5] The high capacity comes from the ability of the matrix to host three additional (excess) lithium ions (Li 4 V 3 O 8 ). 6Because LiV 3 O 8 is a promising mid-voltage material with high capacity and good cycling ability, it has received research attention. However, despite this attention, important physical parameters such as the diffusion coefficient of lithium in the material are not known with precision, varying by at least two orders of magnitude. 7,8 In addition, the material undergoes a phase change at ∼2.5 V from Li 1+x V 3 O 8 to Li 4 V 3 O 8 , 6,9,10 but the equilibrium composition, specifically in the lithium-deficient phase is not known with precision 11 and, to the authors' knowledge, there are no studies on the kinetics of phase change in this material.Through the development of a continuum model, this paper seeks to quantif...

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“…Such systems have been called Weyl semimetals, and their existence has been predicted in several systems [4], [5], [6], [7], [8]; this has generated an intense experimental research, see for instance [9], [10] (and the review [11]). It is of course important to understand the effect of the interactions, which are usually analyzed in effective relativistic models neglecting lattice effects [12], [13], [14], [15].…”

Section: Introductionmentioning

confidence: 99%

“…In this paper we consider a three dimensional interacting fermionic lattice model with a point-like Fermi surface [8] (see also [7]), in presence of an Hubbard interaction. We construct the zero temperature correlations for couplings not too large, proving the persistence of the Weyl semimetallic phase in presence of interactions.…”

Section: Introductionmentioning

confidence: 99%

Weyl Semimetallic Phase in an Interacting Lattice System

Mastropietro

2014

J Stat Phys

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By using Wilsonian Renormalization Group (RG) methods we rigorously establish the existence of a Weyl semimetallic phase in an interacting three dimensional fermionic lattice system, by showing that the zero temperature Schwinger functions are asymptotically close to the ones of massless Dirac fermions. This is done via an expansion which is convergent in a region of parameters, which includes the quantum critical point discriminating between the semimetallic and the insulating phase.

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Calculations of the thermodynamic and kinetic properties of Li1+xV3O8

Cited by 36 publications

References 78 publications

Operando Study of LiV₃O₈Cathode: Coupling EDXRD Measurements to Simulations

Operando Study of LiV₃O₈Cathode: Coupling EDXRD Measurements to Simulations

Discharge, Relaxation, and Charge Model for the Lithium Trivanadate Electrode: Reactions, Phase Change, and Transport

Weyl Semimetallic Phase in an Interacting Lattice System

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Calculations of the thermodynamic and kinetic properties of Li1+xV3O8

Cited by 36 publications

References 78 publications

Operando Study of LiV3O8Cathode: Coupling EDXRD Measurements to Simulations

Operando Study of LiV3O8Cathode: Coupling EDXRD Measurements to Simulations

Discharge, Relaxation, and Charge Model for the Lithium Trivanadate Electrode: Reactions, Phase Change, and Transport

Weyl Semimetallic Phase in an Interacting Lattice System

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Product

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Operando Study of LiV₃O₈Cathode: Coupling EDXRD Measurements to Simulations

Operando Study of LiV₃O₈Cathode: Coupling EDXRD Measurements to Simulations