Defect Chemistry and Li-ion Diffusion in Li2RuO3

Kuganathan, Navaratnarajah; Kordatos, Apostolos; Chroneos, Alexander

doi:10.1038/s41598-018-36865-4

Cited by 34 publications

(39 citation statements)

References 54 publications

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“…The lowest intrinsic defect energy process was calculated to be the cation mixing (anti-site) in which Li and Al exchange their atomic positions. This defect was noted in various oxide materials experimentally and theoretically [37][38][39][40][41][42][43][44][45][46][47]. The primary reasons for this defect include experimental conditions for the preparation of as-prepared compounds and cycling of as-prepared materials particularly in battery applications.…”

Section: Crystal Structure Intrinsic Defect Processes and LI Diffusionmentioning

confidence: 98%

Atomistic Simulations of the Defect Chemistry and Self-Diffusion of Li-ion in LiAlO2

et al. 2019

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Lithium aluminate, LiAlO 2 , is a material that is presently being considered as a tritium breeder material in fusion reactors and coating material in Li-conducting electrodes. Here, we employ atomistic simulation techniques to show that the lowest energy intrinsic defect process is the cation anti-site defect (1.10 eV per defect). This was followed closely by the lithium Frenkel defect (1.44 eV per defect), which ensures a high lithium content in the material and inclination for lithium diffusion from formation of vacancies. Li self-diffusion is three dimensional and exhibits a curved pathway with a migration barrier of 0.53 eV. We considered a variety of dopants with charges +1 (Na, K and Rb), +2 (Mg, Ca, Sr and Ba), +3 (Ga, Fe, Co, Ni, Mn, Sc, Y and La) and +4 (Si, Ge, Ti, Zr and Ce) on the Al site. Dopants Mg 2+ and Ge 4+ can facilitate the formation of Li interstitials and Li vacancies, respectively. Trivalent dopants Fe 3+ , Ni 3+ and Mn 3+ prefer to occupy the Al site with exoergic solution energies meaning that they are candidate dopants for the synthesis of Li (Al, M) O 2 (M = Fe, Ni and Mn) compounds.Energies 2019, 12, 2895 2 of 10 Computational MethodsThe present computational study was based on classical pair-wise potential calculations to describe LiAlO 2 via the General Utility Lattice Program (GULP) code [23,24]. In the present approach, the total energy (lattice energy) is determined by long range (i.e., Coulombic) and short range [i.e., electron-electron repulsive and attractive intermolecular forces (van der Waals forces)]. The latter were modelled using Buckingham potentials (refer to the supplementary information). The van der Waals forces arising from the spontaneous formation of instantaneous dipoles are very important as the formation energy results are sensitive to those forces. The present modelling approach takes into the account of Van der Waals forces as a function of the interatomic distance (r) [23,24]. Two-body Buckingham potential mentioned in the supplementary information consists of two parts. The first part of the equation represents the Pauli repulsion (electron-electron) and the second part denotes the van der Waals interaction. Ionic positions and lattice parameters were relaxed using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm [24]. Convergence criteria dictated that in relaxed configurations, forces on each atom was <0.001 eV/Å. To introduce point defects in the lattice we used the Mott-Littleton methodology [25] similarly to recent work [26][27][28]. It is established that although the present methodology may overestimate the defect formation enthalpies at the dilute limit, the trends will be unchanged [29]. In a thermodynamic perspective defect parameters can be described by comparing the real (i.e., defective) crystal to an isobaric or isochoric ideal (i.e., non-defective) crystal. Defect formation parameters can be interconnected through thermodynamic relations [30,31], with the present atomistic simulations corresponding to the isobaric parameters for the mig...

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Section: Crystal Structure Intrinsic Defect Processes and LI Diffusionmentioning

confidence: 98%

Atomistic Simulations of the Defect Chemistry and Self-Diffusion of Li-ion in LiAlO2

et al. 2019

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“…This suggests that there is a possibility of a small amount of Na on Ni sites (Na Ni ) and Ni on Na sites (Ni •• Na ). This defect has been identified theoretically as a most promising defect in a variety of oxide materials [31][32][33][34][35][36][37][38][39][40][41][42]. During the preparation of as-prepared battery materials and the charge-discharge process, the presence of this defect was noted [35,[56][57][58][59].…”

Section: Intrinsic Defect Processesmentioning

confidence: 95%

“…Divalent doping on the Ni site is a promising stratergy to introduce Na interstitials as explained in the equation 8. A similar stratergy was applied to Li, Na, and Mg-ion battery materials in our previous theoretical studies [36][37][38][39][40][41][42][43][44][45][46][47]. The solution of MO (M = Mg, Co, Fe, Ca, Sr and Ba) was considered using the following reaction:…”

Section: Solution Of Divalent Dopantsmentioning

confidence: 99%

“…Good structural stability was also noted for more than 20 cycles.As there is a limited number of experimental reports available in the literature, further understanding of this material is necessary to optimize its performance in Na-ion batteries. Computational studies at the atomistic level can provide information on intrinsic defect energetics, ion migration and dopant substitution [29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48]. To the best of our knowledge, there is no work reported related to defect and diffusion properties of NaNiO 2 .…”

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Defect, Diffusion and Dopant Properties of NaNiO2: Atomistic Simulation Study

et al. 2019

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Sodium nickelate, NaNiO2, is a candidate cathode material for sodium ion batteries due to its high volumetric and gravimetric energy density. The use of atomistic simulation techniques allows the examination of the defect energetics, Na-ion diffusion and dopant properties within the crystal. Here, we show that the lowest energy intrinsic defect process is the Na-Ni anti-site. The Na Frenkel, which introduces Na vacancies in the lattice, is found to be the second most favourable defect process and this process is higher in energy only by 0.16 eV than the anti-site defect. Favourable Na-ion diffusion barrier of 0.67 eV in the ab plane indicates that the Na-ion diffusion in this material is relatively fast. Favourable divalent dopant on the Ni site is Co2+ that increases additional Na, leading to high capacity. The formation of Na vacancies can be facilitated by doping Ti4+ on the Ni site. The promising isovalent dopant on the Ni site is Ga3+.

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“…Unfortunately, such materials demonstrated low initial Coulomb efficiency; in addition, they exhibited disadvantages of voltage decay and capacity loss upon prolonged cycling . Ru‐based LRLO oxides have received increasing attention as cathodes of LIBs because they can achieve a relatively high Coulomb efficiency, large specific capacity, and good rate capability during the charge‐discharge process. In fact, the Ru‐based LRLO of Li 2 RuO 3 (LRO) was proposed by Goodenough as early as 1988 and was recently comprehensively studied by the Tarascon group .…”

Section: Introductionmentioning

confidence: 99%

A new lithium‐rich layer‐structured cathode material with improved electrochemical performance and voltage maintenance

et al. 2019

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Summary Lithium‐rich layered oxides (LRLOs) are highly attractive cathode materials for next‐generation lithium‐ion batteries because of their high reversible capacity, but poor cycle performance and voltage decay are two main problems that strongly limit their practical applications. These challenges also apply to the Ru‐based LRLOs of Li2RuO3. The Li2RuO3 cathode material is highly attractive because of their high conductivity and favourable electrochemical reaction kinetics. To overcome the problems associated with Li2RuO3, in contrast to normal single atom doping, here, we propose a Na, Cr co‐doping strategy with the design of Li2−xNaxRu0.95Cr0.05O3 (x = 0, 0.02, 0.06, and 0.1) series materials. Cr doping increases capacity, and Na doping suppresses voltage decay. As a result, the discharge capacity of the optimal Li1.98Na0.02Ru0.95Cr0.05O3 sample over 240 mAh/g after 50 charge‐discharge cycles at 0.2 C is maintained, and the capacity retention reaches a value of 80.5% compared with 69.1% for the undoped Li2RuO3. The value of the voltage decay in the Li1.98Na0.02Ru0.95Cr0.05O3 sample is 125 mV after 100 cycles at a rate of 1 C, and the voltage decay is 188.4 mV for the undoped Li2RuO3. This finding will expand the scope for designing novel layered electrodes with excellent performance.

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Defect Chemistry and Li-ion Diffusion in Li2RuO3

Cited by 34 publications

References 54 publications

Atomistic Simulations of the Defect Chemistry and Self-Diffusion of Li-ion in LiAlO2

Atomistic Simulations of the Defect Chemistry and Self-Diffusion of Li-ion in LiAlO2

Defect, Diffusion and Dopant Properties of NaNiO2: Atomistic Simulation Study

A new lithium‐rich layer‐structured cathode material with improved electrochemical performance and voltage maintenance

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