The prediction of a new lithium compound, Li2Sn6O13, is made from a combined first‐principles and classical force‐field approach. The electronic, structural, and mechanical properties of monoclinic Li2SnO3, Li2Ti6O13, and Li2Sn6O13 are explored. The calculated results for the equilibrium lattice parameters are in agreement with the available experimental data. The thermodynamic stabilities of Li2Ti6O13 and Li2Sn6O13 are evaluated. Both compounds are demonstrated to be thermodynamically stable with standard molar formation enthalpies of −5553 and −6740 kJ mol−1, respectively. Reaction energies for delithiation of 6.41 and 6.90 eV atom−1 are also determined for Li2Sn6O13 and Li2Ti6O13, respectively. The predicted voltage of Li insertion/extraction process per Li+/Li is 1.6 V for Li2Sn6O13, comparable to its isostructural counterpart Li2Ti6O13. Electronic band structure calculations indicate the insulating character of Li2SnO3 with an indirect band gap of 4.4 eV, whereas both Li2Ti6O13 and Li2Sn6O13 appear to be semiconductor compounds with band gaps of 3.1 and 3.0 eV, respectivley. The energy barriers for Li+ migration amount to ≈0.5 eV for both materials. Elastic stiffness coefficients and bulk, shear and Young's moduli were also calculated. The Li2Sn6O13 derivative is mechanically stable and can be predicted to be a brittle compound that is more resistant to volume change than Li2Ti6O13. If the Li2Sn6O13 compound could experimentally be prepared by using ion exchange, it could potentially be an efficient material for anodes in lithium‐ion batteries.

The improvement of Li-ion transport properties and doping engineering in Li-ion batteries are currently active research topics in the search for next-generation energy storage devices. In this theoretical work, the...

Rare-earth (RE) doping of BaTiO3 and SrTiO3 has received tremendous research attention in recent decades. Although RE doping has been a particularly popular topic, little or no attention has been given to the contribution from different defect arrangements. In this study, we use a proven interatomic potential model to calculate the binding energies of different RE donor defect (Ba/Sr site doping) configurations in BaTiO3 and SrTiO3. We consider two standard donor defect mechanisms, namely, charge compensation from Ba/Sr vacancies or Ti vacancies. Consistently stronger negative binding energies are calculated for SrTiO3 compared to BaTiO3. We also show that SrTiO3 can accept a larger range of RE ion sizes at the divalent cation site than BaTiO3. This is highlighted by the simple trend of increasing binding energy with decreasing RE ion size found for the defect configurations with a Ti vacancy in SrTiO3. Conversely, defect clustering in BaTiO3 can cause significant strain on the lattice, resulting in positive binding energies. Our results show that one standard defect arrangement per incorporation mechanism cannot be applied to all dopants. We clearly show that the lowest energy defect configuration is dependent on both the dopant and host material. The consequences of these findings for the overall defect incorporation energetics in BaTiO3 and SrTiO3 are also presented.

Lithium stannate (Li2SnO3) is currently being considered as a material for electrode and electrode coating applications in Li-ion batteries. The intrinsic defect formation and Li-ion transport properties of Li2SnO3 doped with divalent and trivalent transition metal dopants (Mn, Fe, Co and Ni) are explored in this work using atomistic simulations. Defect formation simulations reveal that all divalent dopants occupy the Li site with charge compensation through Li vacancies. For trivalent doping, occupation of the Sn site is energetically preferred with charge compensation from Li interstitials. Molecular dynamics simulations reveal that divalent and trivalent dopants increase Li-ion diffusion and reduce its activation energy compared with the undoped system. We show that Li2SnO3 with Li excess or deficiency as a result of doping has improved lithium transport properties. This study highlights the substantial improvement in Li-ion diffusion of Li2SnO3 for both current commercial and next-generation Li-ion battery technologies that can be achieved through transition-metal doping. File list (2) download file view on ChemRxiv Li2SnO3_submitted.pdf (519.88 KiB) download file view on ChemRxiv Li2SnO3 SI.pdf (1.42 MiB)