Calculation of adiabatic barriers for cation diffusion in Li₂O and LiCl crystals

Abstract

We have studied the interstitialcy mechanism for interstitial cation diffusion in L i z 0 and JiCI. First, we have checked and validated the applicability of the ionic approximation and the reliability of the pair-potenrial technique for the investigation of interstitial cation diffusion in ionic crystals. For these purposs we calculated the electronic structure and optical absorption energies for these ions, and compared the atomic structure calculated quantum-chemically with that calculated employing the pairpotential technique. Secondly we have shown that the interstitialcy mechanism is very effective because of the relatively small additional displacements of Ions on moving from the initial configuration to the barrier point in compact sublattices, such as the cation sublatlice in Liz0 or in LiCI. n i s results from the favourable lattice distortion around the interslitial ion. In addition we repon a comparison of results obtained using the MOLSC4T Molt-Littleton code on CaF2 with earlier calculations that employed the HADES program, and obtain a satisfactory measure of agreement between the two sets of calculations.

Direct Calculation of Li-Ion Transport in the Solid Electrolyte Interphase

“…This latter case is the fundamental reason that diffusion in Li 2 CO 3 is energetically predisposed to the knock-off mechanism. Actually, the knock-off diffusion mechanism is quite general for other ionic structures and has been observed in compounds with isolated polyhedral anions or layered tetrahedral networks such as LiBO 2 , Li 2 SO 4 , Li 3 PO 4 , Li 4 SiO 4 , LiF, and Li 2 O, as proposed on the basis of DFT results while lacking experimental confirmation.…”

“…We propose that transport through the other species in the dense layer, which are mainly Li 2 O and LiF, is likely to follow an analogous knock-off mechanism based on some theoretical predictions. 52 The red arrows denote Li + (open circles) diffusion via knock-off in Li 2 CO 3 . Note also that some Li + can diffuse from the dense layer back to the porous layer.…”

Computational Study on the Solubility of Lithium Salts Formed on Lithium Ion Battery Negative Electrode in Organic Solvents

“…A pairwise potential function has been used as the force field in the current simulations, whereas a polarizable function is often used to model ionic solids. 39,42,71 The force field used here is based on a pairwise potential function without many-body-effect terms. Yet, at least, the heat of sublimation for LiF was reasonably reproduced by our calculations.…”

“…Computer modeling of ionic solids has been found to be challenging due to the strong polarization effects, among other factors . Still, computational modeling approaches have been successfully applied to several lithium ions, such as Li 2 O − and Li 2 CO 3 . The primary reason for such a predominantly large number of reports for Li 2 O is due to its interest as an ionic conductor .…”

Generating structural distributions of atomistic models of Li2O nanoparticles using simulated crystallisation

“…7 Equipped with a pristine model, microstructural features such as point defects are now routinely introduced, 8,9 and while extended defects are more problematic, strategies are available to incorporate dislocations, 10,11 grainboundaries (GB) 12 and heterointerfaces [13][14][15] within the atomistic model. However, a real material is likely to comprise several microstructural features-including their synergy of interaction.…”