Synthesis of dandelion-like TiO_2 microspheres as anode materials for lithium ion batteries with enhanced rate capacity and cyclic performances

Dandelion-like TiO2 microspheres consisting of numerous rutile single-crystalline nanorods were synthesized for the first time by a hydrothermal method. Their crystal structure, morphology and electrochemical properties were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and galvanostatic charge and discharge tests. The results show that the synthesized TiO2 microspheres exhibit good rate and cycle performances as anode materials of lithium ion batteries. It can be found that the dandelion-like structure provides a larger specific surface area and the single-crystalline nanorod provides a stable structure and fast pathways for electron and lithium ion transport, which contribute to the rate and cycle performances of the battery.

TiO_2-coated SnO_2 hollow spheres as anode materials for lithium ion batteries

TiO2-coated SnO2 （TCS） hollow spheres, which are new anode materials for lithium ion （Li-ion） batteries, were prepared and characterized with X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, cyclic voltammetry （CV）, and galvanostatic charge/discharge tests. The results obtained from XRD, SEM, and TEM show that TiO2 can be uniforrrdy coated on the surface of SnO2 hollow spheres with the assistance of anionic surfactant. The cyclic voltammograms indicate that both TiO2 and SnO2 exhibit the activity for Li-ion storage. The charge/discharge tests show that the prepared TCS hollow spheres have a higher reversible coulomb efficiency and a better cycling stability than the uncoated SnO2 hollow spheres.

Manganese Dioxide with High Specific Surface Area for Alkaline Battery

The authors reported a facile method for the synthesis of manganese dioxide without any template and catalyst at a low-temperature. The prepared sample was characterized with X-ray diffraction（XRD）, scanning electron microscopy（SEM）, Brunauer-Emmett-Teller（BET） surface analysis, Fourier transform infrared（FTIR） spectrometry, cyclic voltammetry, alternative current（AC） impedance test and battery discharge test. It is found that the prepared sample belongs to α-MnO2 and has a microsphere morphology and a large BET surface area. The electrochemical characterization indicates that the prepared sample displays a larger electrochemical capacitance than the commercial electrolytic manganese dioxides（EMD） in Na2SO4 solution, and exhibits larger discharge capacity than EMD, especially at a high rate discharge condition when it is used as cathode of alkaline Zn/MnO2 battery.

Influence of structure and atom sites on Sn-based anode materials for lithium ion batteries: a first-principle study

To understand the influence of structure and atom sites on the electrochemical properties of Sn-based anode materials,the lithium intercalation–deintercalation mechanisms into SnNi2Cu and SnNiCu2phases were studied using the first-principle plane wave pseudo-potential method.Calculation results showed that both SnNi2Cu and SnNiCu2were unsuitable anode materials for lithium ion batteries.The Sn-based anode structure related to the number of interstitial sites,theoretical specific capacity,and volume expansion ratio.Different atom sites led to different forces at interstitial sites,resulting in variations in formation energy,density of states,and hybrid orbital types.In order to validate the calculated model,the SnNi2Cu alloy anode material was synthesized through a chemical reduction-codeposition approach.Experimental results proved that the theoretical design was reasonable.Consequently,when selecting Snbased alloy anodes,attention should be paid to maximizing the number of interstitial sites and distributing atoms reasonably to minimize forces at these sites and facilitate the intercalation and deintercalation of lithium ion.

Theoretical Studies on the M-M Bonding in Complexes [M_2Cl_4L_2] and [M_2Cl_7L]- (M = Mo, Re; L = Ph_2Ppy, (Ph_2P)_2py)

The structures of complexes [MⅡ2Cl4L2] and [MⅢ2Cl7L]- （M = Mo, Re; L = Ph2Ppy, （Ph2P）2py） were calculated by using density functional theory （DFT） PBE0 method. Based on the optimized geometries, the natural bond orbital （NBO） analyses were carried out to study the nature of Re-Re and Mo-Mo bonds. The conclusions are as follows： the M-M distances in two-Ph2Ppy or （Ph2P）2py complexes [MⅡ2Cl4L2] are shorter than those in mono-Ph2Ppy or （Ph2P）2py complexes [MⅢ2Cl7L]- due to the double bridged N-C-P interactions. For singlet of all complexes, there is ReⅢ-ReⅢ or MoⅡ-MoⅡ quadruply bond in complex [Re2Cl7L]- or [Mo2Cl4L2], while only ReⅡ-ReⅡ or MoⅢ-MoⅢ triply bond in complex [Re2Cl4L2] or [Mo2Cl7L]-. The most stable spin state of 2 and 6, triplet, only contains triple ReⅢ-ReⅢ bond. Because the LPCl → BD＊Re-Re delocalizations weaken the Re-Re bond, the distance of ReⅢ-ReⅢ quadruple bonds in [Re2Cl7L]- is slightly longer than that of ReⅡ-ReⅡ triple bonds in [Re2Cl4L2]. Moreover, due to the delocalizations from the lone pair electrons of the remaining P’ atom to the M-M antibonding orbitals, the M-M distance in （Ph2P）2py complexes is slightly longer than that in Ph2Ppy complexes.

Facile hydrothermal and sol-gel synthesis of novel Sn-Co/C composite as superior anodes for Li-ion batteries

As an anode material in lithium ion battery,the Sn-Co/C composite electrode materials have been successfully synthesized by hydrothermal and sol-gel methods,respectively.The resultant composites were mainly composed of Sn-based oxides,nanometer Sn-Co alloy and carbon.Carbon and Co,acting as buffer materials,can accommodate to the large volume change of active Sn during the discharge-charge process,thus improving the cycling stability.Although charge/discharge curves revealed the excellent cycle performance for samples synthesized by both methods,composites obtained by the sol-gel showed a better dispersion effect of nanoparticles on the carbon matrix and possessed much more improved stable capacity with*624.9 mAh g-1over 100 cycles and that by hydrothermal method only exhibited*299.3 mAh g-1.Therefore,the Sn-Co/C composites obtained by sol-gel synthesis method could be a perfect candidate for anode material of Li-ion storage battery.

Hierarchically 3D structured milled lamellar MoS2/nano-silicon@carbon hybrid with medium capacity and long cycling sustainability as anodes for lithium-ion batteries

A hierarchically 3D structured milled lamellar MoS2/nano-siIicon@carbon hybrid with medium capacity and long-term lifespan is designed by a green and scalable approach using ball milling process and spraydrying/ pyrolysis routes. The microspheres consist of low-content nano-silicon (20 wt%), milled lamellar M0S2 sheets and porous carbon skeletons. A mixture of silicon nanoparticles and M0S2 flakes serves as an inner core, while porous carbon pyrolyzed from petroleum pitch acts as a protective shell. The particular architecture affords robust mechanical support, abundant buffering space and enhanced electrical conductivity, thus effectively accommodating drastic volume variation during repetitive Li+ intercalation/ extraction. The Si/MoS2@C hybrid delivers a high initial discharge specific capacity of 1257.8 mA hg^-1 and exhibits a reversible capacity of 767.52 m A hg^-1 at a current density 100 mA g'1 after 250 cycles. Most impressively, the electrode depicts a superior long-cycling durability with a discharge capacity of 537.6 mA hg^-1 even after 1200 cycles at a current density of 500 m A g^-1. Meanwhile, the hybrid also shows excellent rate performance such as 388.1 mA h g^-1 even at a large current density of 3000 mA g^-1.

PEG软模板法制备锂电池负极材料Fe_3O_4@C纳米复合物（英文）

采用水热法成功合成Fe3O4@C复合物，利用x射线衍射、扫描电子显微镜和透射电子显微镜等手段表征了其形貌和结构．负极材料Fe3O4@C纳米复合物展现了好的循环性能、高的可逆比容量（在电流密度为50 mA／g的条件下，50次循环以后可逆比容量仍达到960mAh／g）、优异的倍率性能（在电流密度1000mA／g充放电条件下，可逆比容量高达650mAh／g）以及稳定的循环性能（50次循环后的比容量损失率低于2．4％）．纳米复合物好优良电化学性能归功予以下2点：（1）30-50nm的球状结构提供了短的扩散通道，无定形碳层不仅在充放电过程中为体积的膨胀提供了缓冲空间而且加强了Fe3O4@C碳棒的导电性能；（2）Fe3O4@C碳的共同作用可以避免Fe3O4@C直接与电解液接触，并且增强纳米复合物整体结构的稳定性．作为锂离子电池负极材料，Fe3O4@C复合材料被认为是高能量锂离子动力电池的理想选择之一．