Variation in surface energy and reduction drive of a metal oxide lithium-ion anode with stoichiometry: a DFT study of lithium titanate spinel surfaces

Morgan, Benjamin J.; Carrasco, Javier; Teobaldi, Gilberto

doi:10.1039/c6ta05980e

Cited by 29 publications

(24 citation statements)

References 47 publications

(59 reference statements)

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“…To our knowledge the surface energies of the orthorhombic Li~0.5TiO2 phase have not been characterized, but studies of anatase TiO2 suggest surface energies ranging from 0.35 -0.52 J/m 2 for the {101} facet and 0.51 -0.96 J/m 2 for the {001} facet, 94,[116][117][118] and a similar range for average surface energies. [119][120][121] Computations of the (111) surface of a comparable material, Li4Ti5O12, indicate that surface energies increase from 0.35 J/m 2 to 0.61 J/m 2 upon lithiation to Li7Ti5O12, 122 so it is conceivable that the lithiated orthorhombic Li~0.5TiO2 phase has an average surface energy that is about 0.11 J/m 2 greater than the tetragonal anatase TiO2 phase. Phase-field simulations of Li and phase boundary flux in single particles provide a more physical probe of the relationship between particle morphology and charging energetics.…”

Section: Energetic Effects Of Nanocrystal Morphology On LI Insertionmentioning

confidence: 99%

Dynamics of Lithium Insertion in Electrochromic Titanium Dioxide Nanocrystal Ensembles

et al. 2021

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is a robust model anode for Li-insertion in batteries. The influence of nanocrystal size on the equilibrium potential and kinetics of Li-insertion is investigated with in operando spectroelectrochemistry of thin film electrodes. Distinct visible and infrared responses correlate with Li-insertion and electron accumulation, respectively, and these optical signals are used to deconvolute Li-insertion from other electrochemical responses, such as double-layer capacitance and electrolyte leakage.Electrochemical titration and phase-field simulations reveal that a difference in surface energies between anatase and lithiated phases of TiO 2 systematically tunes Li-insertion potentials with particle size. However, particle size does not affect the kinetics of Li-insertion in ensemble electrodes. Rather, Li-insertion rates depend on applied overpotential, electrolyte concentration, and initial state-of-charge. We conclude that Li diffusivity and phase propagation are not rate-limiting during Li-insertion in TiO 2 nanocrystals. Both of these processes occur rapidly once the transformation between the low-Li anatase and high-Li orthorhombic phases begins in a particle. Instead, discontinuous kinetics of Li accumulation in TiO 2 particles prior to the phase transformations limits (dis)charging rates. We demonstrate a practical means to deconvolute non-equilibrium charging behavior in nanocrystalline electrodes through a combination of colloidal synthesis, phase field simulations and spectroelectrochemistry. File list (2)download file view on ChemRxiv Manuscript_DynamicsofLithiumInsertion.pdf (2.46 MiB) download file view on ChemRxiv SupportingInfo_DynamicsofLithiumInsertion.pdf (3.34 MiB)

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Section: Energetic Effects Of Nanocrystal Morphology On LI Insertionmentioning

confidence: 99%

Dynamics of Lithium Insertion in Electrochromic Titanium Dioxide Nanocrystal Ensembles

et al. 2021

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“…In all cases, we consider strains corresponding to model {100} A |{100} B coherent interfaces between the doped (Mg,Al) spinel and the target electrode (lithium manganate or lithium titanate spinel). Li 4+3z Ti 5 O 12 is a "zero-strain" material, whose lattice parameters change by <0.1% upon lithium intercalation and extraction [19,48,49] In addition to potential energy profiles from our CI-NEB calculations, we also present electrostatic potential profiles along each path. These are defined as the average electrostatic potential at the site of the mobile ion, evaluated at the optimized geometry of each NEB image.…”

Section: Methodsmentioning

confidence: 99%

Interfacial strain effects on lithium diffusion pathways in the spinel solid electrolyte Li-doped MgAl2O4

O’Rourke

Morgan

2018

Phys. Rev. Materials

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The (Li,Al)-codoped magnesium spinel (Li x Mg 1−2x Al 2+x O 4) is a solid lithium-ion electrolyte with potential use in all-solid-state lithium-ion batteries. The spinel structure means that interfaces with spinel electrodes, such as Li y Mn 2 O 4 and Li 4+3z Ti 5 O 12 , may be lattice matched, with potentially low interfacial resistances. Small lattice parameter differences across a lattice-matched interface are unavoidable, causing residual epitaxial strain. This strain potentially modifies lithium diffusion near the electrolyte-electrode interface, contributing to interfacial resistance. Here, we report a density functional theory study of strain effects on lithium diffusion pathways for (Li,Al)-codoped magnesium spinel, for x Li = 0.25 and x Li = 0.5. We have calculated diffusion profiles for the unstrained materials, and for isotropic and biaxial tensile strains of up to 6%, corresponding to {100} epitaxial interfaces with Li y Mn 2 O 4 and Li 4+3z Ti 5 O 12. We find that isotropic tensile strain reduces lithium diffusion barriers by as much as 0.32 eV, with typical barriers reduced by ∼0.1 eV. This effect is associated with increased volumes of transitional octahedral sites, and broadly follows qualitative changes in local electrostatic potentials. For biaxial (epitaxial) strain, which more closely approximates strain at a lattice-matched electrolyte-electrode interface, changes in octahedral site volumes and in lithium diffusion barriers are much smaller than under isotropic strain. Typical barriers are reduced by only ∼0.05 eV. Individual effects, however, depend on the pathway considered and the relative strain orientation. These results predict that isotropic strain strongly affects ionic conductivities in (Li,Al)-codoped magnesium spinel electrolytes, and that tensile strain is a potential route to enhanced lithium transport. For a lattice-matched interface with candidate spinel-structured electrodes, however, epitaxial strain has a small, but complex, effect on lithium diffusion barriers.

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“…A thorough analysis and reconstruction of the LTO surface is another Taken from Ref. [109] challenging area to explore due to different possible terminations and stoichiometry in both the Li 4 Ti 5 O 12 and Li 7 Ti 5 O 12 surfaces [112]. However, a better understanding of the LTO surface will lead to critical insights about interfacial kinetics and SEI formation which can address an inherent problem such the gassing problem in LTO [113,114] during the charge and discharge process.…”

Section: Challenges and Outlookmentioning

confidence: 99%

Recent Developments in Using Computational Materials Design for High-Performance Li4Ti5O12 Anode Material for Lithium-Ion Batteries

Nasara

Lin

2019

Multiscale Sci. Eng.

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By using knowledge of the fundamental laws of physics, we can determine multiple structural, and electronic property relationships that can be used as complementary guides in obtaining improved experimental information. Computational materials design allows us to fabricate optimized materials based on the understanding of key atomistic processes. In this review, we present an up to date summary of the computational approaches using first principles (ab initio) aimed at designing better lithium titanate oxide Li 4 Ti 5 O 12 as anode material for lithium-ion batteries, and some key challenges and opportunities that lie ahead.

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Variation in surface energy and reduction drive of a metal oxide lithium-ion anode with stoichiometry: a DFT study of lithium titanate spinel surfaces

Abstract: Computational screening of lithium-titanate–spinel surfaces reveals how stoichiometry can strongly affect the thermodynamic drive for reduction at metal-oxide-electrode surfaces.

Cited by 29 publications

References 47 publications

Dynamics of Lithium Insertion in Electrochromic Titanium Dioxide Nanocrystal Ensembles

Dynamics of Lithium Insertion in Electrochromic Titanium Dioxide Nanocrystal Ensembles

Interfacial strain effects on lithium diffusion pathways in the spinel solid electrolyte Li-doped MgAl2O4

Recent Developments in Using Computational Materials Design for High-Performance Li4Ti5O12 Anode Material for Lithium-Ion Batteries

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