Dataset Information

Defect Chemistry and Li-ion Diffusion in Li2RuO3.

ABSTRACT: Layered Li2RuO3 is an important candidate cathode material in rechargeable lithium ion batteries because of its novel anionic redox process and high reversible capacity. Atomistic scale simulations are used to calculate the intrinsic defect process, favourable dopants and migration energies of lithium ion diffusions together with migration paths in Li2RuO3. The Li Frenkel is calculated to be the most favourable intrinsic defect type. The cation anti-site defect, in which Li and Ru ions exchange their positions is 1.89?eV/defect suggesting that this defect would be observed at high temperatures. Long range vacancy assisted lithium diffusion paths were calculated and it is confirmed that the lowest overall activation energy (0.73?eV) migration path is along the ab plane. Trivalent dopants (Al3+, Co3+, Sc3+, In3+, Y3+, Gd3+ and La3+) were considered to create additional Li in Li2RuO3. Here we show that Al3+ or Co3+ are the ideal dopants and this is in agreement with the experimental studies reported on Co3+ doping in Li2RuO3.

SUBMITTER: Kuganathan N

PROVIDER: S-EPMC6345755 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Defect Chemistry and Li-ion Diffusion in Li2RuO3.

Kuganathan Navaratnarajah N Kordatos Apostolos A Chroneos Alexander A

Scientific reports 20190124 1

Layered Li2RuO3 is an important candidate cathode material in rechargeable lithium ion batteries because of its novel anionic redox process and high reversible capacity. Atomistic scale simulations are used to calculate the intrinsic defect process, favourable dopants and migration energies of lithium ion diffusions together with migration paths in Li2RuO3. The Li Frenkel is calculated to be the most favourable intrinsic defect type. The cation anti-si ...[more]

PMID: 30679560

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Project description:Solid electrolytes based on LiBH4 receive much attention because of their high ionic conductivity, electrochemical robustness, and low interfacial resistance against Li metal. The highly conductive hexagonal modification of LiBH4 can be stabilized via the incorporation of LiI. If the resulting LiBH4-LiI is confined to the nanopores of an oxide, such as Al2O3, interface-engineered LiBH4-LiI/Al2O3 is obtained that revealed promising properties as a solid electrolyte. The underlying principles of Li+ conduction in such a nanocomposite are, however, far from being understood completely. Here, we used broadband conductivity spectroscopy and 1H, 6Li, 7Li, 11B, and 27Al nuclear magnetic resonance (NMR) to study structural and dynamic features of nanoconfined LiBH4-LiI/Al2O3. In particular, diffusion-induced 1H, 7Li, and 11B NMR spin-lattice relaxation measurements and 7Li-pulsed field gradient (PFG) NMR experiments were used to extract activation energies and diffusion coefficients. 27Al magic angle spinning NMR revealed surface interactions of LiBH4-LiI with pentacoordinated Al sites, and two-component 1H NMR line shapes clearly revealed heterogeneous dynamic processes. These results show that interfacial regions have a determining influence on overall ionic transport (0.1 mS cm-1 at 293 K). Importantly, electrical relaxation in the LiBH4-LiI regions turned out to be fully homogenous. This view is supported by 7Li NMR results, which can be interpreted with an overall (averaged) spin ensemble subjected to uniform dipolar magnetic and quadrupolar electric interactions. Finally, broadband conductivity spectroscopy gives strong evidence for 2D ionic transport in the LiBH4-LiI bulk regions which we observed over a dynamic range of 8 orders of magnitude. Macroscopic diffusion coefficients from PFG NMR agree with those estimated from measurements of ionic conductivity and nuclear spin relaxation. The resulting 3D ionic transport in nanoconfined LiBH4-LiI/Al2O3 is characterized by an activation energy of 0.43 eV.

Dataset Information

Defect Chemistry and Li-ion Diffusion in Li2RuO3.

Publications

Defect Chemistry and Li-ion Diffusion in Li<sub>2</sub>RuO<sub>3</sub>.

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