Development of a Transferable Variable Charge Potential for the Study of Energy Conversion Materials FeF2 and FeF3

Ma, Ying; Lockwood, Glenn K.; Garofalini, Stephen H.

doi:10.1021/jp207181s

Cited by 14 publications

(28 citation statements)

References 43 publications

(58 reference statements)

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“…In the reconstructed structure (inset in Figure 7 ), the Fe–F bond distance is 1.98 and 1.88 Å, and the angle F–Fe–F and Fe–F–Fe is 82.1°. Compared with the FeF 2 crystal, the calculated Fe–F bond distance and F–Fe–F angle values prove to be in good agreement with the experimental value 30 of 2.05 ± 0.06 Å and 90°. Differently, the calculated F–Fe–F angle and Fe–F bond distance is lower than that of the FeF 2 compound, because no octahedra is presented in the reconstructed Fe surface.…”

Section: Resultssupporting

confidence: 76%

Probing the intrinsic failure mechanism of fluorinated amorphous carbon film based on the first-principles calculations

Zhang

Wang

2015

Sci Rep

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Fluorinated amorphous carbon films exhibit superlow friction under vacuum, but are prone to catastrophic failure. Thus far, the intrinsic failure mechanism remains unclear. A prevailing view is that the failure of amorphous carbon film results from the plastic deformation of substrates or strong adhesion between two contacted surfaces. In this paper, using first-principles and molecular dynamics methodology, combining with compressive stress-strain relation, we firstly demonstrate that the plastic deformation induces graphitization resulting in strong adhesion between two contacted surfaces under vacuum, which directly corresponds to the cause of the failure of the films. In addition, sliding contact experiments are conducted to study tribological properties of iron and fluorinated amorphous carbon surfaces under vacuum. The results show that the failure of the film is directly attributed to strong adhesion resulting from high degree of graphitization of the film, which are consistent with the calculated results.

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Section: Resultssupporting

confidence: 76%

Probing the intrinsic failure mechanism of fluorinated amorphous carbon film based on the first-principles calculations

Zhang

Wang

2015

Sci Rep

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“…While in theses examples we do not explicitly investigate the transferability of the potentials to different systems, we expect that the 4G-HDNNP in general provides an improved transferability compared to 2G and 3G ML potentials due to the underlying physical description of the global charge distribution and the resulting electrostatic energy. This expectation is supported by the fact that even traditional charge equilibration schemes with constant electronegativities are known to work well across different systems 44 . Furthermore, for the related CENT approach a broad transferability has already been demonstrated for different atomic environments 33 .…”

Section: Resultsmentioning

confidence: 97%

A fourth-generation high-dimensional neural network potential with accurate electrostatics including non-local charge transfer

et al. 2021

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Machine learning potentials have become an important tool for atomistic simulations in many fields, from chemistry via molecular biology to materials science. Most of the established methods, however, rely on local properties and are thus unable to take global changes in the electronic structure into account, which result from long-range charge transfer or different charge states. In this work we overcome this limitation by introducing a fourth-generation high-dimensional neural network potential that combines a charge equilibration scheme employing environment-dependent atomic electronegativities with accurate atomic energies. The method, which is able to correctly describe global charge distributions in arbitrary systems, yields much improved energies and substantially extends the applicability of modern machine learning potentials. This is demonstrated for a series of systems representing typical scenarios in chemistry and materials science that are incorrectly described by current methods, while the fourth-generation neural network potential is in excellent agreement with electronic structure calculations.

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“…Therefore, to better understand the voltage overpotential of the FeF 3 cathode, the charge-discharge reaction mechanism of FeF 3 has been investigated with X-ray diffraction (XRD), X-ray adsorption spectroscopy (XAS), ex-situ solid nuclear magnetic resonance (NMR), TEM, and MD simulation. [3][4][5][6][7][8][9][10] The results of these investigations suggested the existence of an intermediate phase containing an Fe 2+ (such as FeF 2 ) during the charge process after the complete conversion reaction (FeF 3 + 3Li + ¼ 3LiF + Fe).…”

Section: Introductionmentioning

confidence: 96%

Discharge and Charge Reaction of Perovskite-type MF3 (M = Fe and Ti) Cathodes for Lithium-ion Batteries

Kitajou

Tanaka

et al. 2017

Electrochemistry

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Conversion-type cathode materials such as perovskite-type MF 3 (M = Fe and Ti) show promise for use in large-scale lithium-ion batteries by virtue of their low cost and large specific capacities. However, the FeF 3 cathode shows a large overpotential during discharge-charge cycles, such that the rechargeable capacity is almost gone after a few cycles. To overcome this drawback, we elucidated the detailed mechanism of the deterioration of the rechargeable capacity for the FeF 3 cathode. In the initial cycle, the cathode returned to the initial FeF 3 structure from LiF and Fe. However, the diffraction peak of LiF and Fe after the 20th cycle was sharper than that after the initial discharge state; that is, the growth of the LiF and Fe crystal contributed to the lower cyclability of FeF 3 . On the other hand, the TiF 3 cathode showed an initial discharge/charge capacity of 730/620 mAh g −1 between 0.5 and 4.0 V, and the discharge-charge overpotential of TiF 3 was still smaller than that of FeF 3 . In addition, the cyclability of the TiF 3 cathode were better than that of the FeF 3 cathode, not only in insertion reaction region, but also in conversion reaction region.

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Development of a Transferable Variable Charge Potential for the Study of Energy Conversion Materials FeF₂ and FeF₃

Cited by 14 publications

References 43 publications

Probing the intrinsic failure mechanism of fluorinated amorphous carbon film based on the first-principles calculations

Probing the intrinsic failure mechanism of fluorinated amorphous carbon film based on the first-principles calculations

A fourth-generation high-dimensional neural network potential with accurate electrostatics including non-local charge transfer

Discharge and Charge Reaction of Perovskite-type <i>M</i>F<sub>3</sub> (<i>M</i> = Fe and Ti) Cathodes for Lithium-ion Batteries

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