Theoretical Study of the Interplay between Lithium Bond and Hydrogen Bond in Complexes Involved with HLi and HCN

The lithium‐ and hydrogen‐bonded complex of HLi? NCH? NCH is studied with ab initio calculations. The optimized structure, vibrational frequencies, and binding energy are calculated at the MP2 level with 6‐311++G(2d,2p) basis set. The interplay between lithium bonding and hydrogen bonding in the complex is investigated with these properties. The effect of lithium bonding on the properties of hydrogen bonding is larger than that of hydrogen bonding on the properties of lithium bonding. In the trimer, the binding energies are increased by about 19 % and 61 % for the lithium and hydrogen bonds, respectively. A big cooperative energy (?5.50 kcal mol^?1) is observed in the complex. Both the charge transfer and induction effect due to the electrostatic interaction are responsible for the cooperativity in the trimer. The effect of HCN chain length on the lithium bonding has been considered. The natural bond orbital and atoms in molecules analyses indicate that the electrostatic force plays a main role in the lithium bonding. A many‐body interaction analysis has also been performed for HLi? (NCH)_N (N=2–5) systems.     

Electrochemistry of Electrode Materials Containing S−Se Bonds for Rechargeable Batteries

Sulfur (S) and selenium (Se) have been considered as promising high capacity cathode materials for rechargeable batteries. They have differences in their physical properties (e.g., electronic conductivity) but the same number of electrons in their outermost shells, which leads to similarity in their electrochemical behavior in batteries. In recent years, some efforts have been taken to combine them in electrodes in the hope of improved battery performance. The S−Se bonds of these electrode materials lead to unusual properties and intriguing electrochemical behavior, which have attracted increasing interest. In this Minireview, electrode materials containing S−Se bonds are summarized, including inorganic S_xSe_y solid solutions, organic compounds, and organic–inorganic hybrid materials. Our understanding in these materials is still premature, but they have shown unique properties to be electrode materials. We hope this Minireview could provide a new insight into the design, synthesis, and understanding of these materials, which could enable high energy density rechargeable batteries.     

Hydrogen‐Bonding‐Mediated Synthesis of Atomically Thin TiO2 Films with Exposed (001) Facets and Applications in Fast Lithium Insertion/Extraction

Ultrathin two‐dimensional (2D) crystalline materials show high specific surface area (SA) of high energy (HE) facets, imparting a significant improvement in their performances. Herein we report a novel route to synthesize TiO₂ nanofilms (NFs) with atomic thickness (<2.0 nm) through a solvothermal reaction mediated by the hydrogen‐bonding networks constructed by hydroquinone (HQ). The resultant TiO₂ NFs have nearly 100 % exposed (001) facets and give an extremely high SA up to 487 m² g^?1. The synergistic effect of HQ and choline chloride plays a vital role in the formation of TiO₂ NFs and in the exposure of HE (001) facets. Because of its ultrathin feature and exposed (001) facet, the N₂‐annealled TiO₂ NFs showed fast kinetics of lithium insertion/extraction, demonstrating foreseeable applications in the energy storage.     

Cooperative and Diminutive Interplay Between Lithium and Dihydrogen Bonding in F3YLi…︁NCH…︁HMH and F3YLi…︁HMH…︁HCN Triads (Y=C,Si; M=Be,Mg)

The F₃YLi…NCH…HMH and F₃YLi…HMH…HCN triads (Y=C, Si; M=Be, and Mg) are connected by lithium and dihydrogen bonds. To understand the properties of the systems better, the corresponding dyads are also studied. Molecular geometries, binding energies, infrared spectra and NMR properties of monomers, dyads, and triads are investigated at the MP2/6‐311++G** computational level. Particular attention is paid to parameters, such as cooperative energies, and many‐body interaction energies. Triads with the HMH molecule located at the end of the chain, show energetic cooperativity ranging between ?3.66 to ?7.59 kJ mol^‐1. When the HMH molecule is located in the middle, the obtained cluster is diminutive with an energetic effect between 3.49 to 5.17 kJ mol^‐1. The electronic properties of the complexes are analyzed using parameters derived from the atoms in molecules (AIM) methodology.     

双甲基化大豆苷元磺酸锂的合成及晶体结构

以大豆苷元为先导化合物,合成了水溶性异黄酮化合物4’,7-二甲氧基异黄酮磺酸锂．X射线单晶衍射分析表明：标题化合物属于三斜晶系,空间群Pi,晶胞参数为：a=0．7732（2）nm,b=1．874（5）nm,c=1．920（5）nm,α=111．224（4）°,β=90．21（5）°,γ=100．68（4）°Z=2．标题化合物的分子组成为[Li（H2O）4]2（C17H13O4SO3）2·4H2O,其中两种类型的锂离子均被4分子水所配位．[Li（H2O）4]^＋、C17H13O4SO3^-和H2O之间存在多种氢键作用;氢键作用以及阴阳离子之间的静电引力作用共同将标题化合物组装成具有三维网络结构的超分子．     

Influence of the Li⋅⋅⋅π Interaction on the H/X⋅⋅⋅π Interactions in HOLi⋅⋅⋅C6H6⋅⋅⋅HOX/XOH (X=F,Cl, Br,I) Complexes

The influences of the Li???π interaction of C₆H₆???LiOH on the H???π interaction of C₆H₆???HOX (X=F, Cl, Br, I) and the X???π interaction of C₆H₆???XOH (X=Cl, Br, I) are investigated by means of full electronic second‐order Møller–Plesset perturbation theory calculations and “quantum theory of atoms in molecules” (QTAIM) studies. The binding energies, binding distances, infrared vibrational frequencies, and electron densities at the bond critical points (BCPs) of the hydrogen bonds and halogen bonds prove that the addition of the Li???π interaction to benzene weakens the H???π and X???π interactions. The influences of the Li???π interaction on H???π interactions are greater than those on X???π interactions; the influences of the H???π interactions on the Li???π interaction are greater than X???π interactions on Li???π interaction. The greater the influence of Li???π interaction on H/X???π interactions, the greater the influences of H/X???π interactions on Li???π interaction. QTAIM studies show that the intermolecular interactions of C₆H₆???HOX and C₆H₆???XOH are mainly of the π type. The electron densities at the BCPs of hydrogen bonds and halogen bonds decrease on going from bimolecular complexes to termolecular complexes, and the π‐electron densities at the BCPs show the same pattern. Natural bond orbital analyses show that the Li???π interaction reduces electron transfer from C₆H₆ to HOX and XOH.     

Cation Additive Enabled Rechargeable LiOH-Based Lithium–Oxygen Batteries

Lithium–oxygen (Li–O₂) batteries have attracted extensive research interest due to their high energy density. Other than Li₂O₂ (a typical discharge product in Li–O₂ batteries), LiOH has proved to be electrochemically active as an alternative product. Here we report a simple strategy to achieve a reversible LiOH-based Li–O₂ battery by using a cation additive, sodium ions, to the lithium electrolyte. Without redox mediators in the cell, LiOH is detected as the sole discharge product and it charges at a low charge potential of 3.4 V. A solution-based reaction route is proposed, showing that the competing solvation environment of the catalyst and Li⁺ leads to LiOH precipitation at the cathode. It is critical to tune the cell chemistry of Li–O₂ batteries by designing a simple system to promote LiOH formation/decomposition.     

A Two-Dimensional Metal–Organic Polymer Enabled by Robust Nickel–Nitrogen and Hydrogen Bonds for Exceptional Sodium-Ion Storage

Organic electrode materials suffer from low electronic conductivity and poor structure stability. Herein, a metal–organic polymer, Ni-coordinated tetramino-benzoquinone (Ni-TABQ), is synthesized via d–π hybridization. The polymer chains are stitched by hydrogen bonds to feature as a robust two-dimensional (2D) layered structure. It offers both electron conduction and Na⁺ diffusion pathways along the directions of the polymer chains and the hydrogen bonds. With both the conjugated benzoid carbonyls and imines as the redox centers for the insertion and extraction of Na⁺, the Ni-TABQ delivers high capacities of about 469.5 mAh g⁻¹ at 100 mA g⁻¹ and 345.4 mAh g⁻¹ at 8 A g⁻¹. The large capacities are sustained for 100 cycles with almost 100 % coulombic efficiencies. The exceptional electrochemical performance is attributed to the unique 2D electron conduction and Na⁺ diffusion pathways enabled by the robust Ni–N and hydrogen bonds.     

纳米级锂离子电池正极材料LiFePO4*

LiFePO₄以其价格便宜,稳定性好,无毒等优点而倍受关注。但是非纳米LiFePO₄的电子导电率低及扩散系数小限制了其在锂离子电池领域的大规模应用。而纳米电极材料以其特有的优点很好的解决了这些问题。本文主要综述了国内外合成纳米级LiFePO₄ 的不同方法及所得材料的对电化学性能和相关机理,以及纳米LiFePO₄作为锂离子正极材料存在的问题。     

The basicity of unsaturated hydrocarbons as probed by hydrogen-bond-acceptor ability: bifurcated N-H+ ...pi hydrogen bonding

The competitive substitution of the anion (A(-)) in contact ion pairs of the type [Oct3NH+]B(C6F5)4 (-) by unsaturated hydrocarbons (L) in accordance with the equilibrium Oct3NH+...A(-) + nL right arrow over left arrow [Oct3NH+...Ln]A(-) has been studied in CCl4. On the basis of equilibrium constants, K, and shifts of nuNH to low frequency, it has been established that complexed Oct3NH...+Ln cations with n=1 and 2 are formed and have unidentate and bifurcated N--H+...pi hydrogen bonds, respectively. Bifurcated hydrogen bonds to unsaturated hydrocarbons have not been observed previously. The unsaturated hydrocarbons studied include benzene and methylbenzenes, fused-ring aromatics, alkenes, conjugated dienes, and alkynes. From the magnitude of the redshifts in the N--H stretching frequencies, Delta nuNH, a new scale for ranking the pi basicity of unsaturated hydrocarbons is proposed: fused-ring aromatics相似文献   

Two Cd(Ⅱ) and Cu(Ⅱ) Complexes Based on 1-Butylbenzimidazole: Crystal Structures and Weak Interactions

1-Butylbenzimidazole L reacted with Cd(NO3)2·4H2O to afford complex [CdL(NO3)3H2O]·[HL] 1. The heptacoordinated Cd(Ⅱ) center adopts a distorted pentagongal bipyramidal geometry, and complex [CdL(NO3)3H2O]-entity and the protonated benzimidazium salt [HL]+ are connected via N-H···O hydrogen bond to form a dimeric unit [CdL(NO3)3H2O]·[HL]. A 3-D supramolecular network of 1 is formed through N-H···O and O-H···O hydrogen bonds together with π-π stacking interactions. Reaction of L with CuCl2 afforded a mononuclear complex, [CuL2Cl2] 2, in which the tetracoordinated Cu(II) center adopts a distorted tetrahedral geometry. In contrast, 2-D supramolecular layers of 2 are formed by C-H···Cl hydrogen bonds. The fluorescent emission spectra of L, 1 and 2 are described.     

锂无机固体电解质

全固态锂离子二次电池具有更大能量密度和更高的安全使用性能,在未来的电动汽车和蓄能电站上有很好的应用前景。本文对一些典型的锂无机固体电解质进行分类讨论,对它们的性能、结构和导电机理进行评述。这些固体电解质具有较高的离子导电率,是目前的研究热点。文章总结了影响其导电率的几个重要因素以及作为理想锂无机固体电解质的几个基本要求。     

金属锂二次电池研究进展

本文综述了近年来金属锂二次电池的研究进展,主要包括金属锂负极的表面改性、SEI膜的形成和调制、电解质体系的改进及研发,以及电池制备工艺等,并在综述各方面进展的基础上对金属锂二次电池未来的研究方向进行了展望。