Yazar "Thornton, Katsuyo" seçeneğine göre listele

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    Öğe
    Dynamics of phase transformation in LiFePO4 in battery electrode
    (International Conference on Solid-Solid Phase Transformations in Inorganic Materials 2015, 2015) Yu, Huichia; Orvañanos, Bernardo; Akyıldız, Öncü; Thornton, Katsuyo
    [No abstract available]
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    Öğe
    Particle-size and morphology dependence of the preferred interface orientation in LiFePO4 nano-particles
    (Royal Society of Chemistry, 2014) Abdellahi, Aziz; Akyıldız, Öncü; Malik, Rahul; Thornton, Katsuyo; Ceder, Gerbrand
    We gain new insights into the equilibrium properties and potential two-phase lithiation mechanisms in LiFePO4 nano-particles by conducting a first-principles investigation of the anisotropic chemical interfacial energy landscape in LiFePO4. The chemical interfacial energy per unit area along the ac plane is found to be remarkably low (7 mJ m-2) with respect to the bc (115 mJ m-2) and ab (95 mJ m-2) chemical interfacial energies. Because chemical interfacial energy and coherency strain energy have different anisotropies, the thermodynamically stable interface orientation is shown to depend both on the particle size and on the particle morphology. In particular, ac interfaces are favored for isotropic particles below 40 nm. This indicates that, if experimentally-relevant nano-particles were to (de)lithiate under a thermodynamic two-phase mechanism, the resulting front would be orientated along the ac plane, and not along the bc plane as is assumed in most lithiation models in the literature. © the Partner Organisations 2014.
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    Öğe
    The thermodynamic stability of intermediate solid solutions in LiFePO4 nanoparticles
    (Royal Society of Chemistry, 2016) Abdellahi, Aziz; Akyıldız, Öncü; Malik, Rahul; Thornton, Katsuyo; Ceder, Gerbrand
    Theoretical predictions from first principles and recent advances in in situ electrochemical characterization techniques have confirmed the presence of solid-solution states during electrochemical (de)lithiation of LiFePO4 nanoparticles. Surprisingly, however, such thermodynamically unfavorable solid solution states have been observed at rates as low as 0.1C. Given the high diffusivity of Li in LiFePO4 and the thermodynamic instability of homogeneous solid solution states, spinodal decomposition to a thermodynamically favorable two-phase state is expected to occur on time scales as rapid as 1-100 ms. In this paper, we resolve this apparent paradox by demonstrating that, given the symmetry of the low-energy solid-solution Li/Va orderings and the 1D character of Li diffusion, spinodal decomposition from a solid solution preferentially leads to the formation of a diffuse ac interface with a large intermediate solid-solution region, as opposed to the commonly assumed bc interface. Our first principles predictions not only rationalize the persistence of solid-solution states at low-to-moderate C-rates in high-rate LiFePO4 electrodes, but also explain the observations of large intermediate solid-solution regions at an ac interface in single LixFePO4 particles quenched from a high-temperature solid solution. © The Royal Society of Chemistry 2016.