Unique solvation structure induced by anionic Cl in aqueous zinc ion batteries.

Aqueous zinc ion batteries (AZIBs) have garnered significant attention in large-scale static energy storage battery systems due to their low cost, high safety and environmental friendliness. However, it has some inherent problems during operation, such as the occurrence of side reactions (hydrogen evolution reaction, HER) and anode corrosion, formation of by-products and growth of metal dendrites. To analyze the mechanism of generation from aspect of the electrolyte solvation structure and make cell efficiency further improvements based on it, so we use DFT calculations to find the most stable solvation structure in AZIBs with ZnCl2 as the electrolyte and analyze it. We define the relative concentration Cr, and calculate different groups metal cation cluster structures such as [Zn(H2O)n]2+, [ZnCl(H2O)n]+, [ZnCl2(H2O)n] and [ZnCl3(H2O)n]- that exist at different Cr. We discuss the effect of different clusters formed due to the Cr variations on the battery performance in terms of three aspects: the structural conformation, the cluster characteristics (including the hydrogen bonding network, bond lengths, bond angles, as well as the electrostatic potential ESP) and the cluster performance (including the adsorption energy Ea, binding energy Eb, and desolvation energy Edes). The results shows that the electrolyte metal cation Zn2+ can be coordinated with up to six H2O molecules in first shell, and this metal cation solvation structure contributes to the occurrence and formation of side reactions and by-products, which reduces the battery efficiency. Increasing the electrolyte anion Cl- concentration by appropriately increasing the Cr helps to desolvate the metal cation cluster structure, which greatly improves the battery efficiency and suppresses the side reactions and by-products. Yet the improvement effect was not obviously further improved by further increasing the Cl- concentration.

Theoretical study on the role of magnesium chloride complexes induced by different magnesium-to-chlorine ratios in magnesium-sulfur batteries.

In magnesium-sulfur batteries, electrolyte exploration is vital for developing high-energy-density, safe, and reliable batteries. This study focused on cyclic THF and chain DME, representative solvents in ether electrolytes. MgCl2, an ideal anionic salt, forms mono-nuclear (MgCl2(DME)2), bi-nuclear ([Mg2(µ-Cl)2(DME)4]2+), and tri-nuclear ([Mg3(µ-Cl)4(DME)5]2+) complexes in DME. With increasing salt concentration, these complexes sequentially form. Under lower salt concentrations, THF and MgCl2 form mono-nuclear complexes ([MgCl2(THF)4]) and continue to form bi-nuclear complexes ([Mg2(µ-Cl)3(THF)6]+). However, at higher salt concentrations, bi-nuclear complexes ([Mg2(µ-Cl)3(THF)6]+) directly form in THF. Comparing HOMO-LUMO values, [Mg(DME)3]2+ is easily oxidized. Energy gaps decrease with Cl- ion addition, enhancing solution conductivity. Ratios of Mg2+ and Cl- in S-reduction complexes differ, suggesting DME is better at a low Mg/Cl ratio, and THF at a high Mg/Cl ratio. This study contributes to understanding complexes and enhancing Mg-S battery performance.

First-principles investigation on multi-magnesium sulfide and magnesium sulfide clusters in magnesium-sulfide batteries.

Because of the abundance of magnesium and sulfur and their low cost, the development of magnesium sulfur batteries is very promising. In particular, the battery performance of nanoscale (MgS)n clusters is much better than that of bulk sized MgS. However, the structures, stability, and properties of MgxSy and (MgS)n clusters, which are very important to improve the performance of Mg-S batteries, are still unexplored. Herein, the most stable structures of MgxSy (x = 1-8, y = 1-8) and (MgS)n (n = 1-10) are reliably determined using the structure search method and density functional theory to calculate. According to calculation results, MgS3 and Mg6S8 may not exist in the actual charging and discharging products of magnesium sulfide batteries. The (MgS)n (n ≥ 5) clusters exhibit intriguing cage-like structures, which are favorable for eliminating dangling bonds and enhancing structural stability. Compared to the MgS monomer, each sulfur atom in the clusters is coordinated with more magnesium atoms, thus lengthening the Mg-S bond length and decreasing the Mg-S bond activation energy. Notably, with the increase of dielectric constant of electrolyte solvent, compared to the DME (ε = 7.2), THF (ε = 7.6) and C2H4Cl2 (ε = 10.0), MgxSy and (MgS)n clusters are most stable in the environment of C3H6O (ε = 20.7). It can delay the transformation of magnesium polysulfide to the final product MgS, which is conducive to improving the performance of Mg-S batteries. The predicted characteristic peaks of infrared and Raman spectra provide useful information for in situ experimental investigation. Our work represents a significant step towards understanding (MgS)n clusters and improving the performance of Mg-S batteries.

First-Principles-Based Optimized Design of Fluoride Electrolytes for Sodium-Ion Batteries.

Because of the abundance and low cost of sodium, sodium-ion batteries (SIBs) are next-generation energy storage mediums. Furthermore, SIBs have become an alternative option for large-scale energy storage systems. Because the electrolyte is a critical component of SIBs, fluorination is performed to improve the cycling performance of electrolytes. Based on the first-principles study, we investigated the effects of the type, quantity, and relative position relationships of three fluorinated units, namely -CF1, -CF2, and -CF3, on the cyclic ester molecule ethylene carbonate (EC) and the linear ether molecule 1,2-dimethoxylethane (DME). The optimal fluorination was proposed for EC and DME by studying the bond length, highest occupied molecular orbital, lowest unoccupied lowest orbital, and other relevant parameters. The results revealed that for EC, the optimal fluorination is 4 F fluorination based on four -CF1 units; for DME, CF3CF1CF1-, CF3CF2CF2-, CF3CF1CF2CF3, and CF3CF2CF2CF3, four combinations of three -CF1, -CF2, and -CF3 units are optimal. The designed fluorinated EC and DME exhibited a wide electrochemical stability window and high ionic solvation ability, which overcomes the drawback of conventional solvents and can improve SIB cycling performance.

Comparative Gut Microbiome in Trachypithecus leucocephalus and Other Primates in Guangxi, China, Based on Metagenome Sequencing.

The Trachypithecus leucocephalus (white-headed langur) is a highly endangered, karst-endemic primate species, inhabiting the karst limestone forest in Guangxi, Southwest China. How white-headed langurs adapted to karst limestone and special dietary remains unclear. It is the first time to study the correlation between the gut microbiome of primates and special dietary, and environment in Guangxi. In the study, 150 fecal samples are collected from nine primates in Guangxi, China. Metagenomic sequencing is used to analyze and compare the gut microbiome composition and diversity between white-headed langurs and other primates. Our results indicate that white-headed langurs has a higher diversity of microbiome than other primates, and the key microbiome are phylum Firmicutes, class Clostridia, family Lachnospiraceae, and genera Clostridiates and Ruminococcus, which are related to the digestion and degradation of cellulose. Ten genera are significantly more abundant in white-headed langurs and François' langur than in other primates, most of which are high-temperature microbiome. Functional analysis reveals that energy synthesis-related pathways and sugar metabolism-related pathways are less abundant in white-headed langurs and François' langur than in other primates. This phenomenon could be an adaptation mechanism of leaf-eating primates to low-energy diet. The gut microbiome of white-headed langurs is related to diet and karst limestone environment. This study could serve as a reference to design conservation breeding, manage conservation units, and determine conservation priorities.

An orbital principle to design P2-NaxMO2 cathode materials for sodium-ion batteries.

Layered oxide materials are regarded to be the most promising high-performance cathode materials for sodium-ion batteries owing to their high working voltage and facile synthesis. Here, we study the influences of 3d transition metals on the cohesive energies, structural changes and operating voltages of P2-NaxMO2 during discharge based on first-principles calculations. Our results confirm that the performances of P2-NaxMO2 are associated with the chemical properties of the transition metals. In addition to this, we disclose that the involved orbitals of the 3d transition metal also greatly impact the electrochemical performance of the P2-NaxMO2 material during discharge according to the analysis of electronic structures. The jumps in the working voltage and volume during discharge are closely related to the occupation of the eg and t2g orbitals. Therefore, it is necessary to ensure that the discharge or charge process is carried out in one degenerate orbital to avoid jumps in the voltage and volume of the material. Our results could shed a light on the subsequent design of layered oxide cathodes with high cycle stability and a smooth voltage curve.

The reference genome and transcriptome of the limestone langur, Trachypithecus leucocephalus, reveal expansion of genes related to alkali tolerance.

BACKGROUND: Trachypithecus leucocephalus, the white-headed langur, is a critically endangered primate that is endemic to the karst mountains in the southern Guangxi province of China. Studying the genomic and transcriptomic mechanisms underlying its local adaptation could help explain its persistence within a highly specialized ecological niche. RESULTS: In this study, we used PacBio sequencing and optical assembly and Hi-C analysis to create a high-quality de novo assembly of the T. leucocephalus genome. Annotation and functional enrichment revealed many genes involved in metabolism, transport, and homeostasis, and almost all of the positively selected genes were related to mineral ion binding. The transcriptomes of 12 tissues from three T. leucocephalus individuals showed that the great majority of genes involved in mineral absorption and calcium signaling were expressed, and their gene families were significantly expanded. For example, FTH1 primarily functions in iron storage and had 20 expanded copies. CONCLUSIONS: These results increase our understanding of the evolution of alkali tolerance and other traits necessary for the persistence of T. leucocephalus within an ecologically unique limestone karst environment.

Diphenyl polysulfides: cathodes with excellent lithiation performance and high specific energy for LSBs.

Reversible lithium-sulfur batteries (LSBs) are considered one of the most promising next-generation energy storage systems. However, the shuttling effect of lithium polysulfide significantly weakens the electrochemical properties and the cycle life, hindering its practical application. Organo-sulfides are unique materials with low cost, profuse content and high capacity. Here, via quantum chemical calculations, we introduce a class of diphenyl polysulfides, PhS n Ph (2 ≤ n ≤ 15), which are all structurally stable, confirmed by calculation of their Gibbs free energies. The theoretical specific energy of PhS15Ph is high, up to 2632 W h kg-1, exceeding that of S8. By calculating the bond dissociation energy of S-S in PhS n Ph molecules, we analyze the breaking processes of the S-S bonds in each step of lithiation. The microscopic mechanism of the fast reaction kinetics of PhS n Ph cathodes is explored. It is phenyl that prevents the formation of soluble long-chain polysulfide molecules (Li2S4, Li2S6, Li2S8) in the lithiation process, efficiently weakening the "shuttle effect".

Risk of dementia in seniors with newly diagnosed diabetes: a population-based study.

OBJECTIVE: To study whether diabetes onset in late life is a risk factor for dementia. RESEARCH DESIGN AND METHODS: We conducted a population-based matched cohort study using provincial health data from Ontario, Canada. Seniors with (n = 225,045) and without newly diagnosed diabetes (n = 668,070) between April 1995 and March 2007 were followed until March 2012 for a new diagnosis of dementia. Cox proportional hazards modeling was used to compare the risk of dementia between groups after adjusting for baseline cardiovascular disease, chronic kidney disease (CKD), hypertension, and other risk factors. RESULTS: Over this period, we observed 169,114 new cases of dementia. Individuals with diabetes had a modestly higher incidence of dementia (2.68 vs. 2.62 per 100 person-years) than those without diabetes. In the fully adjusted Cox model, the risk of dementia was 16% higher among our subgroup with diabetes (hazard ratio [HR] 1.16 [95% CI 1.15-1.18]). Adjusted HRs for dementia were 1.20 (95% CI 1.17-1.22) and 1.14 (95% CI 1.12-1.16) among men and women, respectively. Among seniors with diabetes, the risk of dementia was greatest in those with prior cerebrovascular disease (HR 2.03; 95% CI 1.88-2.19), peripheral vascular disease (HR 1.47; 95% CI 1.19-1.82), and CKD (HR 1.44; 95% CI 1.38-1.51), and those with one or more hospital visits for hypoglycemia (HR 1.73; 95% CI 1.62-1.84). CONCLUSIONS: In this population-based study, newly diagnosed diabetes was associated with a 16% increase in the risk of dementia among seniors. Preexisting vascular disease and severe hypoglycemia were the greatest risk factors for dementia in seniors with diabetes.

Enhancing the lateral photovoltaic effect by coating the absorbing film on metal-oxide-semiconductor structure.

By coating with a carbon film and graphene sheet (GS) on position-sensitive detectors based on the metal-oxide-semiconductor structure, sensitivity, linearity, and saturation power are significantly improved. We attribute this enhancement of absorptivity to lasers. The improvement effect of carbon film is more obvious than that of GS coating because of GS's high conductivity.