Vibrational Spectroscopic Study on Ion Solvation and Association of Lithium Perchlorate in 4-Methoxymethyl-ethylene Carbonate

Solvation interaction and ion association in solutions of lithium perchlorate/4-methoxymethyl-ethylene carbonate （MEC） have been studied by using Infrared and Raman spectra as a function of concentration of lithium perchlorate. The splitting of ring deformation band and ring ether asymmetric stretching band, and the change of carbonyl stretching band suggest that there should be a strong interaction between Li^＋ and the solvent molecules, and the site of solvation should be the oxygen atom of carbonyl group. The apparent solvation number of Li^＋ was calculated by using band fitting technique. The solvation number was decreased from 3.3 to 1.1 with increasing the concentration of LiClO4/MEC solutions. On the other hand, the band fitting for the ClO4^- band revealed the presence of contact ion pair, and free ClO4^- anion in the concentrated solutions.     

锂离子电池用多孔硅/石墨/碳复合负极材料的研究

在两步高能球磨和酸蚀条件下制得了多孔硅/石墨复合材料，并对其进行碳包覆制成多孔硅/石墨/碳复合材料。通过TEM，SEM等测试手段研究了多孔硅材料的结构。作为锂离子电池负极材料，电化学测试结果表明多孔硅/石墨/碳复合材料相比纳米硅/石墨/碳复合材料有更好的循环稳定性。同时，改变复合体配比、热解碳前驱物、粘结剂种类和用量也会对材料的电化学性能产生较大的影响。其中使用质量分数为10％的LA132粘结剂的电极200次循环以后充电容量保持在649.9 mAh·g^-1，几乎没有衰减。良好的电化学性能主要归因于主活性体-多孔硅颗粒中的纳米孔隙很好地抑制了嵌锂过程中自身的体积膨胀，而且亚微米石墨颗粒和碳的复合也减轻了电极材料的体积效应并改善了其导电性。     

Lithium bromide in acetonitrile: Thermodynamics,theory, and simulation

A variety of methods has been used for the study of lithium bromide solutions in acetonitrile yielding by their combination reliable information on different levels of approximation. Osmotic coefficients based on precise vapor pressure measurements are reproduced by CM (chemical model) and HNC (hypernetted chain) calculations and by BD (brownian dynamics) simulations. The results of neutron scattering experiments are treated with the help of HNC and BD methods. Hartree-Fock calculations on isolated LiBr pairs and solvated lithium ions yield reliable particle distances and reveal the geometry of the lithium solvation sphere.     

Intercalation and exchange reactions of clay minerals and non-clay layer compounds

Presently, a large variety of layered materials are synthesized that are able to intercalate neutral guest molecules or to exchange inorganic and organic ions for interlayer ions. Several of these materials are also found as minerals.The intracrystalline reactivity of a few selected compounds will be described and compared to clay minerals:

Ternäre intermetallische Phasen des Lithiums mit Elementen der 4. Neben- und 5. Hauptgruppe mit statistischer Metallverteilung im „Kationen”︁-Teilgitter

Ternary Intermetallic Phases of Lithium, Transition Metals of the 4^th Group and Elements of the 5^th Maingroup with Statistical Metal Distribution in the ?Cation”?-Substructure The results of X-ray investigations and neutron diffraction on new and in some cases already known [1, 2] ternary intermetallic phases of Lithium with transition metals of the 4^th group (b) and those of the 5^th main group (X = P, As, Sb, Bi) will be reported. They crystallize in a partly ?filled”? antifluorite type structure with a statistical Li/B-distribution in the tetrahedral sites. The structures are obviously stabilized by small amounts of enclosed d-elements.     

C60: A host lattice for the intercalation of oxygen?

The investigation of structural and electronic properties of the novel family of fullerenes depends on the existence of pure reference materials. Sublimation of the van-der Waals solids is a suitable purification method. Little attention has been paid to the question about the air stability of such sublimed samples in form of crystals or thin films. A combination of thermal desorption spectroscopy, thermal analysis and diffuse reflectance FT-IR spectroscopy is used to show the extent to which oxygen from dry air is intercalated into fullerenes and which detrimental reactivity occurs from attempts to thermally remove (nneal) air-exposed samples. The conclusion is that any fullerene sample exposed to air will be transformed in part into a polymeric non-fullerene carbon upon thermal treatment to above 400 K irrespective of its initial purity.Dedicated to Professor Dr. rer. nat. Dr. h.c. Hubertus Nickel on the occasion of his 65th birthday     

银负载量对网状TiO_2柔性薄膜电极储锂性能的影响

采用水热法结合银镜反应制备出一系列不同Ag负载量(2.2%、4.0%、6.4%,w/w)改性的3D纳米网状结构Ag@Ti O2薄膜电极。利用电感耦合等离子体技术(ICP)、X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和X射线能谱(EDX)等表征手段测试所合成材料的形貌及成分,实验结果表明Ag纳米颗粒可以成功沉积在Ti O2纳米线表面。电化学测试数据则表明,4.0%(w/w)负载量的Ag@Ti O2相比于未改性和其他负载量的Ti O2纳米线具有更好的倍率性能和更稳定的可逆容量。在50,100,200,400,800和1 200 m A·g~(-1)的电流密度条件下,该改性电极的放电容量可分别达到261.4,253.7,239.5,216.5,193.1和185.1 m Ah·g~(-1),在200 m A·g~(-1)下循环80次后容量保持率仍能达到99.8%。