Effects of Gallium Doping in Garnet-Type Li7La3Zr2O12 Solid Electrolytes

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 by the Ga3+ addition (>90% connectivity retained up to x = 0.30 in Li7–3xGaxLa3Zr2O12). Interestingly, two compositional regions are predicted for bulk Li+ ion conductivity in the cubic phase: (i) a decreasing trend for 0 ≤ x ≤ 0.10 and (ii) a relatively flat trend for 0.10 < x ≤ 0.30. This conductivity behavior is explained by combining analyses using percolation theory, van Hove space time correlation, the radial distribution function, and trajectory density

Ethnic differences and predictors of racial and religious discriminations among Malaysian Malays and Chinese

Studies on racial and religious discriminations in Malaysia tend to be avoided. This is due to their sensitive nature, possibly becoming political ammunition, and individuals being accused of seditious intent. Much that is necessary to discuss discrimination in Malaysia remains unclear. It is not known to what extent contact between groups is undesirable especially as neighbors in Malaysia. This study examined ethnic differences and predictors of racial and religious discriminations among 1200 Malaysians (319 Chinese and 881 Malays). Discrimination was conceptualized through having the attitude of not wanting people of a different race or a different religion as neighbors. Ethnic differences in discriminating against others were found to be significant. Malays showed higher means of not wanting neighbors of a different race or religion compared to Chinese. Demographic factors and beliefs reflecting conservatism were not good predictors, explaining only slight variances. However, a person who discriminates based on religion was consistently a predictor of exhibiting racial discrimination, and vice-versa, with approximately double the odds among Malays. The finding highlights a strong interplay between race and religion, suggesting that Chinese and Malays conflate the two together

Trans-influence of nitrogen-and sulfur-containing ligands in trans-platinum complexes: A density functional theory study

Transplatin complexes with N-or S-containing ligands were modeled in silico. We performed density functional theory calculations using the B3LYP exchange-correlation functional as incorporated in the Gaussian03 software package. The 6-311+G(d,p) basis set was used for first-row elements, and the LanL2DZ with effective core potential (ECP) basis set was used for platinum. The various neutral N-or S-containing ligands do not give rise to considerable variations in the trans-bond lengths and strengths. The reactions leading to complex formation also yield close net energy values. Nevertheless, Pt complexes with anionic thiolate (CH3S-) ligand are significantly more energetically stable by at least ∼5eV (∼115kcalmol-1 or ∼484kJmol-1) compared to transplatin complexes with other ligands. An examination of the net energetic stabilities and dipole moments of transplatin complexes with N-and S-ligands led us to hypothesize adenine to be the most suitable candidate among naturally occurring organic ligands (X) for the development of trans-Pt(NR)(NR′)Cl(X) anticancer agent. © 2009 IOP Publishing Ltd

Investigating the dendritic growth during full cell cycling of garnet electrolyte in direct contact with Li metal.

All-solid-state batteries including a garnet ceramic as electrolyte are potential candidates to replace the currently used Li-ion technology, as they offer safer operation and higher energy storage performances. However, the development of ceramic electrolyte batteries faces several challenges at the electrode/electrolyte interfaces, which need to withstand high current densities to enable competing C-rates. In this work, we investigate the limits of the anode/electrolyte interface in a full cell that includes a Li-metal anode, LiFePO4 cathode, and garnet ceramic electrolyte. The addition of a liquid interfacial layer between the cathode and the ceramic electrolyte is found to be a prerequisite to achieve low interfacial resistance and to enable full use of the active material contained in the porous electrode. Reproducible and constant discharge capacities are extracted from the cathode active material during the first 20 cycles, revealing high efficiency of the garnet as electrolyte and the interfaces, but prolonged cycling leads to abrupt cell failure. By using a combination of structural and chemical characterization techniques, such as SEM and solid-state NMR, as well as electrochemical and impedance spectroscopy, it is demonstrated that a sudden impedance drop occurs in the cell due to the formation of metallic Li and its propagation within the ceramic electrolyte. This degradation process is originated at the interface between the Li-metal anode and the ceramic electrolyte layer and leads to electromechanical failure and cell short-circuit. Improvement of the performances is observed when cycling the full cell at 55 °C, as the Li-metal softening favors the interfacial contact. Various degradation mechanisms are proposed to explain this behavior

Insights into the lithium-ion conduction mechanism of garnet-type cubic Li5La3Ta2O12 by ab-initio calculations

© 2015 American Chemical Society.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 mechanism was determined to be facilitated by a cooperative hopping process characterized by long, multiple-site successive hops with a very small time scale for fluctuations at intermediate positions. A comparative study is also carried out between LLTaO and garnet-type Li7La3Zr2O12 (LLZrO), another candidate solid electrolyte

Mechanical failure of garnet electrolytes during Li electrodeposition observed by in-operando microscopy

Metallic Li anodes are key to reaching high energy densities in next-generation solid-state batteries, however, major problems are the non-uniform deposition of Li at the interface and the penetrative power of Li metal during operation, which cause failure of the ceramic electrolyte, internal short-circuits and a premature end of battery life. In this work, we explore the anode-electrolyte interface instability of a Li metal-garnet electrolyte system during Li electrodeposition, and its implications for mechanical fracture, Li metal propagation, and electrolyte failure. The degradation mechanism was followed step-by-step during in-operando electrochemical cycling using optical and scanning electron microscopy. High amounts of Li electrodeposition in a localized zone of the interface lead to ceramic fracture followed by an electrode-to-electrode electrical connection via a conductor Li metal filament. This work enables deeper understanding of battery failure modes in all-solid-state batteries containing a ceramic electrolyte membrane

Insights into the Lithium-Ion Conduction Mechanism of Garnet-Type Cubic Li₅La₃Ta₂O₁₂ by ab-Initio Calculations

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 mechanism was determined to be facilitated by a cooperative hopping process characterized by long, multiple-site successive hops with a very small time scale for fluctuations at intermediate positions. A comparative study is also carried out between LLTaO and garnet-type Li₇La₃Zr₂O₁₂ (LLZrO), another candidate solid electrolyte