Randy Jalem 교수

The garnet-type Li7La3Zr2O12 (LLZO) belonging to cubic symmetry (space group Ia3̅d) is considered as one of the most promising solid electrolyte materials for all-solid state lithium ion batteries. In this study, the diffusion coefficient and site occupancy of Li ions within the 3D network structure of the cubic LLZO framework have been investigated using ab initio molecular dynamics calculations. The bulk conductivity at 300 K is estimated to be about 1.06 × 10–4 S cm–1 with an energy barrier o

Garnet-type Li7La3Zr2O12 (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 force-field-based simulations, the effects of Ga3+ doping in LLZrO. We confirm the stabilizing effect of Ga3+ on the cubic phase. We also determine that Ga3+ addition does not lead to any appreciable structural distortion. Li site connectivity is not significantly deteriorated

Safe and robust batteries are urgently requested today for power sources of electric vehicles. Thus, a growing interest has been noted for fabricating those with solid electrolytes. Materials search by density functional theory (DFT) methods offers great promise for finding new solid electrolytes but the evaluation is known to be computationally expensive, particularly on ion migration property. In this work, we proposed a Bayesian-optimization-driven DFT-based approach to efficiently screen for

The density functional theory (DFT) method is a widely used tool that can guide targeted searches exploring numerous possible chemistries according to any property of interest. However, acquiring accurate DFT results from a large chemical search space is still a major challenge for computationalists because it requires considerable time and resources. Therefore, advances in this field are urgently needed. In particular, the development of new materials for Li ion batteries would benefit greatly

Lithium-ion conductive solid oxide electrolytes are receiving increasing attention for the development of high-performance all-solid state rechargeable Li-ion batteries. In this study, we report an effective search method that uses a combination of ab initio calculations and multivariate analysis to find potential solid oxide electrolyte materials with low Li-ion hopping energies (EAs) among 66 olivine-type oxides with an ordered structure LiMXO4 (main group M2+–X5+, M3+–X4+). The ionic size of

The guiding principle for the design of inorganic compounds with high ionic conductivity has been extensively sought to realize next-generation all-solid-state batteries (ASSBs). Recently, a sulfide-type Na+ ion conductor, cubic Na3SbS4 with W doping (Na2.88Sb0.88W0.12S4), was reported with unprecedentedly high ionic conductivity of 3.2 × 10–2 S cm–1, making it now a champion solid electrolyte for Na-ASSB (A. Hayashi et al., Nat. Commun. 2019, 10, 5266). Herein, density functional theory molecul

The ongoing search for fast Li-ion conducting solid electrolytes has driven the deployment surge on density functional theory (DFT) computation and materials informatics for exploring novel chemistries before actual experimental testing. Existing structure prototypes can now be readily evaluated beforehand not only to map out trends on target properties or for candidate composition selection but also for gaining insights on structure-property relationships. Recently, the tavorite structure has b

We report a comprehensive first-principles DFT study on (electro)chemical stability, intrinsic defects, and ionic conductivity improvement by halide doping of Na 3 SbS 4 electrolyte for all-solid-state Na batteries.

The decomposition of garnet Li₇La₃Zr₂O₁₂ during the charge process can proceed <italic>via</italic> a reaction with a carbon additive in a solid-state cell.

Garnet-type solid electrolytes are a class of materials that could potentially revolutionize Li-ion battery technology. In this work, ab-initio-based MD simulations have been performed to investigate the ion dynamics in pure garnet-type cubic Li5La3Ta2O12 (LLTaO) over the temperature range from 873 to 1773 K. A strong tendency for disorder in the Li sublattice was verified for LLTaO that explains the relative ease of stabilizing the reported cubic phase for this material. The Li+ conduction mech

Li-rich inverse perovskites have recently attracted great interest as solid electrolytes for all-solid-state batteries. Although so far, there are only relatively few candidate solid electrolytes that were reported with an inverse perovskite structure, this is despite the large variety of crystal systems and structure derivatives that can exist in such materials. In this work, we studied by density functional theory calculations the material space of more than 500 inverse-perovksite-type in sili

Increasing attention has been paid to materials informatics approaches that promise efficient and fast discovery and optimization of functional inorganic materials. Technical breakthrough is urgently requested to advance this field and efforts have been made in the development of materials descriptors to encode or represent characteristics of crystalline solids, such as chemical composition, crystal structure, electronic structure, etc. We propose a general representation scheme for crystalline

The lithium diffusivity behavior at the grain boundaries of β-Li 3 PS 4 solid electrolytes is strongly dependent on the grain boundary type and the degree of disorder.

The global minimum structures for Li(x)CoO(2) compositions where 0 ≤ x ≤ 1 were probed by using a hybrid evolutionary algorithm with an underlying ab initio structural relaxation scheme. The method successfully predicted experimentally observed variants of layered configurations at various degrees of lithiation and the spinel (Fd3[combining macron]m) phase at x = 1/2. New low-energy non-layered host structures at x < 1/2 were also revealed. These structures can be formed from the usual layered c