A comparison of mathematical models for phase-change in high-rate LiFePO4 cathodes

Dargaville, Steven; Farrell, Troy

doi:10.1016/j.electacta.2013.08.014

Cited by 26 publications

(31 citation statements)

References 61 publications

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“…It is important to stress that our successful fitting of MPET is for low-rate experiments, probing the slow dynamics of electrode phase transformations. At high rates, the original MPET formulation with Butler-Volmer kinetics and no statistical hetereogeneities [30] can have difficulty fitting experimental data [50]. The framework of MPET is very general, however, and it is likely that some more effects must be added to describe the full range of operating conditions.…”

Section: Iron Phosphate: Two Phasesmentioning

confidence: 99%

Phase Transformation Dynamics in Porous Battery Electrodes

Ferguson

Bazant

2014

Electrochimica Acta

113

171

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Porous electrodes composed of multiphase active materials are widely used in Li-ion batteries, but their dynamics are poorly understood. Two-phase models are largely empirical, and no models exist for three or more phases. Using a modified porous electrode theory based on non-equilibrium thermodynamics, we show that experimental phase behavior can be accurately predicted from free energy models, without artificially placing phase boundaries or fitting the open circuit voltage. First, we simulate lithium intercalation in porous iron phosphate, a popular two-phase cathode, and show that the zero-current voltage gap, sloping voltage plateau and under-estimated exchange currents all result from size-dependent nucleation and mosaic instability. Next, we simulate porous graphite, the standard anode with three stable phases, and reproduce experimentally observed fronts of colorchanging phase transformations. These results provide a framework for physics-based design and control for electrochemical systems with complex thermodynamics.

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Section: Iron Phosphate: Two Phasesmentioning

confidence: 99%

Phase Transformation Dynamics in Porous Battery Electrodes

Ferguson

Bazant

2014

Electrochimica Acta

113

171

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“…Modeling and simulation provide a crucial complement to experimental measurements, and in the case of Li X FePO 4 , a number of theoretical predictions about nanoscale phase behavior have preceded and motivated experiments [7]. The earliest models of the intercalation process assumed reduced dimensionality of the primary nanoparticles in order to capture the essential physics with fewer parameters and faster computations [5,54,35], as required for models of porous electrodes with large numbers of interacting particles [22,30,31,51]. In particular, many experimentally observed features in nonequilibrium phase separation have been successfully predicted by depth-averaged Allen-Cahn Reaction phasefield models [7] where concentration variations are confined to the ac plane.…”

Section: Introductionmentioning

confidence: 99%

Interplay of phase boundary anisotropy and electro-auto-catalytic surface reactions on the lithium intercalation dynamics in LiXFePO4 plateletlike nanoparticles

Nadkarni

Rejovitsky

Fraggedakis

et al. 2018

Phys. Rev. Materials

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Experiments on single crystal Li X FePO 4 (LFP) nanoparticles indicate rich nonequilibrium phase behavior, such as suppression of phase separation at high lithiation rates, striped patterns of coherent phase boundaries, nucleation by binarysolid surface wetting and intercalation waves. These observations have been successfully predicted (prior to the experiments) by 1D depthaveraged phase-field models, which neglect any subsurface phase separation. In this paper, using an electrochemo-mechanical phase-field model, we investigate the coherent non-equilibrium subsurface phase morphologies that develop in the abplane of platelet-like single-crystal platelet-like Li X FePO 4 nanoparticles. Finite element simulations are performed for 2D plane-stress conditions in the abplane, and validated by 3D simulations, showing similar results. We show that the anisotropy of the interfacial tension tensor, coupled with electroautocatalytic surface intercalation reactions, plays a crucial role in determining the subsurface phase morphology. With isotropic interfacial tension, subsurface phase separation is observed, independent of the reaction kinetics, but for strong anisotropy, phase separation is controlled by surface reactions, as assumed in 1D models. Moreover, the driven intercalation reaction suppresses phase separation during lithiation, while enhancing it during delithiation, by electro-autocatalysis, in quantitative agreement with in operando imaging experiments in * equal contributions † bazant@mit.edu single-crystalline nanoparticles, given measured reaction rate constants.arXiv:1802.05847v1 [cond-mat.mtrl-sci]

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“…However, cathode materials with inferior electrochemical performances restrict the development of LIBs as a bottleneck. The widely used cathode materials, such as LiCoO 2 [7][8], LiFePO 4 [9][10][11], LiNi 1/3 Mn 1/3 Co 1/3 O 2 and LiMn 2 O 4 [12][13], with low discharge capacities (lower than 200 mAh g −1 )…”

Section: Introductionmentioning

confidence: 99%