Concerted Migration Mechanism in the Li Ion Dynamics of Garnet-Type Li7La3Zr2O12

Jalem, Randy; Yamamoto, Yoshihiro; Shiiba, Hiromasa; Nakayama, Masanobu; Munakata, Hirokazu; Kasuga, Toshihiro; Kanamura, Kiyoshi

doi:10.1021/cm303542x

Cited by 219 publications

(259 citation statements)

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“…Vertical lines (dashed and solid) show the discrete peak locations for the tetragonal phase (note that due to cell edge mismatch, the first two peak lines from the left are shifted to the right with respect to the cubic phase). It should also be mentioned at this point that owing to the scale of the phase space involved (1944 Li sites for a 3 × 3 × 3 supercell), standard MD sampling and annealing would require a prohibitively long computation time to reach the exact Li ordering of the tetragonal phase (i.e., into the 8a, 16f, and 32g sites 25 ) when starting at the high-T Li disordered cubic phase. In other words, in the present computation, we would only observe the tendency for Li ordering in the cooling direction, that is, tetragonal signatures in the Li−Li g(r) profiles become more pronounced as we go down to low temperature range (starting from a high temperature phase) but the exact g(r) fingerprint of the fully ordered Li arrangement would not be reached.…”

Section: Chemistry Of Materialsmentioning

confidence: 99%

“…Also, 1/3 of the Td sites should be occupied in a regular arrangement such that Td Li + do not have a first nearest Td site neighbors, that is, 8a Li−16e Li pair contribution (for first NN Td site pairs) should become weaker at r ≈ 4 Å. 25 In both models (x = 0 and x = 0.30), the first peak can be readily assigned to the characteristic Td-Oh Li intersite contribution. At 800 K, Li disordering is depicted in Figure 3a by the smoother peaks due to the ease of Li diffusivity (Figure 3c, e).…”

Section: Chemistry Of Materialsmentioning

confidence: 99%

“…For example, in our previous density functional theory (DFT) molecular dynamics (MD) calculations, we found that the complex mechanism for self-diffusion of Li + ions in LLZrO proceeds in a cooperative manner and is governed by two crucial features: (i) the restriction imposed for occupied site-to-site interatomic separation and (ii) the apparent unstable residence of the Li + ion at the Td site due to local Li−Li repulsion effect. 25 Meier et al further provided information to establish the difference between the Li + ion diffusion mechanism of the tetragonal and cubic phase through DFT-based MD and metadynamics simulations; the former has a fully collective nature or synchronous motion while the latter has an asynchronous motion governed by single-ion jumps and induced collective motion. 26 In another simulation using classical MD, with a BV-based Morse-type force field, Adams et al predicted that for the garnet Li 7−x La 3 (Zr 2−x M x )O 12 system (x = 0, 0.25; M = Ta 5+ , Nb 5+ ): (i) the lithium distribution just above the cubic phase transition closely resembles that in the tetragonal phase and that (ii) pentavalent doping can enhance ionic conductivity by increasing the vacancy concentration and by reducing local Li ordering.…”

Section: ■ Introductionmentioning

confidence: 99%

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Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

et al. 2015

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Garnet-type Li 7 La 3 Zr 2 O 12 (LLZrO) is a candidate solid electrolyte material that is now being intensively optimized for application in commercially competitive solid state Li + ion batteries. In this study we investigate, by forcefield-based simulations, the effects of Ga 3+ doping in LLZrO. We confirm the stabilizing effect of Ga 3+ on the cubic phase. We also determine that Ga 3+ addition does not lead to any appreciable structural distortion. Li site connectivity is not significantly deteriorated by the Ga 3+ addition (>90% connectivity retained up to x = 0.30 in Li 7−3x Ga x La 3 Zr 2 O 12 ). Interestingly, two compositional regions are predicted for bulk Li + ion conductivity in the cubic phase: (i) a decreasing trend for 0 ≤ x ≤ 0.10 and (ii) a relatively flat trend for 0.10 < x ≤ 0.30. This conductivity behavior is explained by combining analyses using percolation theory, van Hove space time correlation, the radial distribution function, and trajectory density. ■ INTRODUCTIONSolid electrolytes with high lithium ionic conductivity are now being actively investigated for application in commercially competitive all-solid-state rechargeable lithium-ion batteries. Among them, Li-based garnet oxides have shown promise for meeting the much needed safety and reliability requirements of today's commercial lithium ion batteries.1−7 One of the garnet compositions being considered is the cubic Li 7 La 3 Zr 2 O 12 (LLZrO), this is due to its stability with elemental lithium and a total conductivity on the order of 10 −4 S/cm. 2 Its structure is usually defined in the Ia3̅ d space group with Li cations partiallly occupying 24d tetrahedral (Td) and 48g/96h octahedral (Oh) sites, La cations fully occupying 24c dodecahedral sites, Zr cations fully occupying 16a octahedral sites, and O anions fully occupying the 96h sites (see Figure 1). However, a more stable tetragonal symmetry (I4 1 /acd) has also been reported to exist at room temperature, with Li ordering in three crystallographic sites: one at the 8a site, which forms a subset of the cubic garnet 24d site, and the other two highly distorted 16f and 32g sites which, when combined, are equivalent to the cubic garnet 48g/96h sites. 8,9 This ordering is responsible for the low bulk Li + ion conductivity measured for tetragonal LLZrO, a value on the order of 1 × 10 −6 S/cm at room tempertaure.

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Section: Chemistry Of Materialsmentioning

confidence: 99%

Section: Chemistry Of Materialsmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

et al. 2015

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“…Jalem et al 24 identified a concerted Li + migration mechanism in cubic LLZO via AIMD simulations. Meier et al 108 compared the differences in Li + diffusion in tetragonal and cubic phases using a similar technique.…”

Section: Llzo Garnetmentioning

confidence: 99%

“…Many proposed design 'rules of thumb' for fast alkali conductivity, for example, 3D interstitial networks with bottlenecks of sufficient size, 23 the presence of alkali ion disorder, 24 having a polarizable anion framework, 25 body-centered cubic system close-packed anion frameworks, 26 and so on, are limited to specific chemistries or structure types and are not readily generalizable. There has also been limited success in identifying new frameworks that share these features.…”

Section: Introductionmentioning

confidence: 99%

Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

Deng

Ong

2016

NPG Asia Mater

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The facile conduction of alkali ions in a crystal host is of crucial importance in rechargeable alkali-ion batteries, the dominant form of energy storage today. In this review, we provide a comprehensive survey of computational approaches to study solid-state alkali diffusion. We demonstrate how these methods have provided useful insights into the design of materials that form the main components of a rechargeable alkali-ion battery, namely the electrodes, superionic conductor solid electrolytes and interfaces. We will also provide a perspective on future challenges and directions. The scope of this review includes the monovalent lithium-and sodium-ion chemistries that are currently of the most commercial interest. NPG Asia Materials (2016) 8, e254; doi:10.1038/am.2016.7; published online 25 March 2016 INTRODUCTIONThe facile conduction of alkali ions in a crystal is of critical importance in energy storage. Today, the dominant form of energy storage in consumer electronics is the rechargeable lithium-ion (Li-ion) battery, 1-5 a device that functions entirely on the basis of the reversible transport of Li + ions. With one of the highest energy densities of known energy storage technologies, Li-ion batteries are finding increasingly large-scale applications in electrified transportation and grid storage. In recent years, there has also been a resurgence of interest in rechargeable sodium-ion (Na-ion) batteries, 6-12 which function on the same basic principle but with Na + instead of Li + because of concerns regarding the abundance and cost of lithium. Figure 1 shows a representation of a rechargeable alkali-ion battery. The typical electrode in an alkali-ion battery is an intercalation compound, which, as the name implies, stores alkali ions by inserting them into its crystal structure in a topotactic manner. During discharge, A + ions are transported from the anode, through the electrolyte and into the cathode. The reverse happens during charge. Throughout this review, we will adopt the customary terminology of defining the 'cathode' as the positive electrode during discharge, even though the formal definition of the cathode changes depending on whether the charging or discharging process is being referred to. Current cathodes are typically transition metal oxides, and the insertion/removal of each A + in the cathode is accompanied by the concomitant reduction/oxidation of a transition metal ion to accommodate the compensating insertion/removal of an electron. Graphitic carbon is the most common anode.The performance of a rechargeable alkali-ion battery depends crucially on the ease with which alkali ions move in the host crystal of the cathode and anode, in the electrolyte, and in the electrodeelectrolyte interface. Poor alkali transport in any part of the battery

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Introduction to Rational Molecular Modeling Approaches

Jalem

Nakayama

2015

Perovskites and Related Mixed Oxides

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Concerted Migration Mechanism in the Li Ion Dynamics of Garnet-Type Li₇La₃Zr₂O₁₂

Cited by 219 publications

References 47 publications

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

Introduction to Rational Molecular Modeling Approaches

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Concerted Migration Mechanism in the Li Ion Dynamics of Garnet-Type Li7La3Zr2O12

Cited by 219 publications

References 47 publications

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li5La3Ta2O12 by ab-Initio Calculations

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li5La3Ta2O12 by ab-Initio Calculations

Computational studies of solid-state alkali conduction in rechargeable alkali-ion batteries

Introduction to Rational Molecular Modeling Approaches

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Concerted Migration Mechanism in the Li Ion Dynamics of Garnet-Type Li₇La₃Zr₂O₁₂

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations