水热/溶剂热法制备锂电池负极材料碳气凝胶/Fe2O3及其电化学性能

采用水热/溶剂热法,通过在碳气凝胶(CA)表面负载纳米Fe2O3颗粒,制备了具有不同外观形貌的CA/Fe2O3复合负极材料.通过X射线粉末衍射(XRD)、扫描电镜(SEM)和热重(TG)等测试手段表征了碳气凝胶、Fe2O3及CA/Fe2O3的结构、形貌和Fe2O3负载率,并对复合负极的电化学储锂性能进行了研究.结果表明,采用水热或溶剂热法时,在碳气凝胶表面合成的Fe2O3颗粒分别呈橄榄球状和微球状.电化学结果表明,采用溶剂热法合成的CA/Fe2O3复合材料作为锂电池负极材料具有较高的储锂容量和倍率性能,在100 mA·g-1电流密度下循环50次,可逆容量为634.9 mAh·g-1,充电容量保持率高达97.9;.     

花状SnS2微球锂离子电池负极材料制备及性能

以SnCl4·5H2O和L-半胱氨酸为原料,通过水热法制备了直径约为1μm的均匀花状SnS2微球.利用X-射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X-射线光电子能谱(XPS)和氮气吸附-脱附测试(BET)对产物进行表征.电化学性能测试表明,花状SnS2微球作为锂离子电池负极材料,在1C电流密度下首次放电容量达到1379.5 mAh·g-1,30周后放电容量保持在400 mAh·g-1.     

石墨烯/Fe2O3纳米复合材料的制备及其储锂性能研究

采用软化学方法控制氧化石墨表面含氧官能团的数量,一步完成了石墨烯/Fe2O3纳米复合材料的控制合成.采用XRD和Raman光谱分析及TEM表征复合材料的组成、结构和微观形貌特征,并对石墨烯/Fe2O3复合负极的电化学储锂性能进行了研究.结果表明,石墨烯/Fe2O3复合材料作为锂离子电池负极材料具有较高的储锂容量和倍率性能,充放电循环性能稳定.在100 mA/g的电流密度下循环100次,可逆容量为606 mAh/g,放电效率保持在91;;在2 A/g下放电容量是其在250 mA/g下放电容量的58.2;.     

CoO/NiO/CoNi复合材料的制备及其储锂性能的研究

将Al72 Ni13.4 Co14.6十次准晶作为前驱体合金,通过去合金化法制备了CoO/NiO/CoNi微纳复合材料作为锂离子电池负极材料。采用X射线衍射( XRD)、扫描电镜( SEM)等材料结构分析方法对产物进行表征。通过恒电流充放电技术研究该电极材料的电化学性能,结果表明,在200 mA·g-1电流密度下,首次充放电容量为417 mAh·g-1和617 mAh·g-1,库伦效率为67.6;,经过500圈循环后放电容量仍保持为585 mAh·g-1,表现出良好的循环性能。     

新型锂离子电池复合负极材料3Li4Ti5O12·NiO的制备及性能研究

采用喷雾干燥法合成了3Li4Ti5O12·NiO复合负极材料.XRD结果表明,复合NiO没有改变Li4Ti5On的晶体结构.SEM结果表明,样品为直径0.5～3 μm的球形颗粒.电化学测试结果表明,3Li4Ti5O12·NiO较Li4Ti5O12倍率性能和循环性能得到极大地提高.该复合材料在0.1C、1C和20 C倍率下的放电比容量分别为372.8 mAh·g-1、252.6 mAh·g-1和204.8 mAh·g-1,在20C倍率下循环300次后的容量保持率为98.7;.     

钠离子电池负极材料二氧化钛的氮离子掺杂改性研究

二氧化钛(TiO2)作为钠离子电池负极材料有着极大的应用前景,但是,低的电导率限制其大规模应用.通过静电纺丝的方法,制备出碳复合的锐钛矿二氧化钛(TiO2)样品,并对样品进行氮掺杂,作为自支撑钠离子电池负极材料.通过XRD、SEM、XPS、充放电测试对其进行结构、形貌分析和电化学性能研究.结果发现,氮离子成功的掺入晶体内部,且对TiO2的晶型没有影响.氮离子掺杂后,样品N-TiO2的倍率性能有了明显的提高.在10 A· g-1电流密度下,样品TiO2和N-TiO2的可逆比容量分别为134.3 mAh· g-1和212.1 mAh· g-1.在1 A· g-1的电流密度下,样品N-TiO2和TiO2的可逆比容量分别为192.4 mAh· g-1、124.5 mAh· g-1,循环1000圈后,放电比容量依然高达195.5 mAh· g-1、120.9 mAh· g-1,样品N-TiO2和TiO2均具有优异的循环稳定性,但氮离子掺杂后,比容量有了显著的提高.实验表明,氮离子掺杂后,材料中产生的Ti3+和氧空位可以提高电子电导率和Na+在材料中的扩散效率,使得其电化学性能有了明显的改善.     

尿素共沉淀法制备LiNi0.8Co0.2O2正极材料及其电化学性能

采用尿素共沉淀法合成了LiNi0.8Co0.2O2锂离子电池正极材料,研究了烧结温度、锂源摩尔配比对LiNi08Co02O2晶形结构、形貌以及电化学性能的影响.结果表明,尿素共沉淀法合成LiNi0.8Co02O2样品最佳工艺条件是800℃温度条件下烧结10 h、锂过量5;合成的样品具有较好的电化学性能,以0.2C倍率充放电时首次充放电容量分别为206.4 mAh·g-1和191.6 mAh·g-1,循环30次后容量为178.2 mAh·g-1.     

锂离子电池柔性负极材料CoO纳米线@C/碳布复合材料

本文提出了一种简便、可规模化制备CoO纳米线@C/碳布(CC)复合材料的方法，该复合材料可用作无粘结剂锂离子电池负极。首先通过简单的水热和煅烧法制备了CoO纳米线@碳布复合材料，再通过葡萄糖溶液浸渍和煅烧获得具有三维立体结构的CoO纳米线@C/CC复合电极材料。碳包覆的CoO纳米线均匀地分散在碳布上，形成导电的碳网络。在碳布上原位生长的CoO纳米线可以有效缩短锂离子的转移路径，降低接触电阻。碳涂层厚度约为1 nm,显著抑制了锂离子嵌入/嵌出过程中活性材料的粉碎，以及CoO在电解液中的直接暴露。结果表明CoO纳米线@C/CC复合材料用作锂离子电池的无粘结剂负极时，具有良好的充放电性能和循环稳定性。电流密度为1 A·cm^-2时，200次循环后的比容量为863 mAh·cm^-2(容量保持率75.83%)。本研究为柔性锂离子电池负极材料的制备提供了一种可行的新选择。     

负极集流体为CNT导电纸的锂离子电池及其性能

采用碳纳米管(Carbon nanotubes,CNT)导电纸替代传统的金属铜箔作锂离子电池的负极集流体,石墨作为活性材料.在0.2C倍率条件下电池首次放电比容量高达815.7 mAh·g-1,可逆放电比容量为474.0 mAh·g-1,是铜箔作为负极集流体锂电池(236 mAh·g-1)的2倍,10次循环后电池容量保持率97.2;.CNT导电纸有良好的强度、韧性、吸液性能.相比铜箔集流体,其结构可有效保证负极材料与碳纳米管导电纸集流体间的紧密接触,减少界面电阻,增加电子传导通道.碳纳米管导电纸有望替代传统铜箔成为新一代锂离子电池用集流体.     

新型复合正极材料5LiMn0.9Fe0.1PO4·Li3V2(PO4)3/C的制备及电化学性能研究

用固相法制备了5LiMn0.9Fe0.1PO4·Li3V2(PO4)3/C复合正极材料.采用XRD、SEM、TEM和电化学测试等对材料进行了表征.结果表明,复合材料由LiMn0.9Fe0.1PO4和Li3V2(PO4)3两相组成,不含其它杂质.Li3V2(PO4)3的加入使得LiMn0.9Fe0.1PO4的电化学性能得到极大地提高.该复合材料在0.05 C和1C倍率下的放电比容量分别为162.8 mAh·g-1和129.6mAh·g-1,在1C倍率下循环50次后的容量保持率为90.1;.     

Triethyl ammonium salt of O,O′-bis(p-tolyl)dithiophosphate, [Et3NH]+[(4-MeC6H4O)2PS2]−

Triethyl ammonium Salt of O,O′-bis(p-tolyl)dithiophosphate and O,O′-bis(m-tolyl)dithiophosphate have been obtained by reaction of p- and m-cresol, respectively with P₂S₅ in toluene and have been characterized by elemental analysis, IR, ¹H and ³¹P NMR spectroscopy. The molecular structure of O,O′-bis(p-tolyl)dithiophosphate has been determined. Crystal data: [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻: Monoclinic, P2₁/c, a=15.2441(9) ?, b=10.415(2) ?, c=3.9726(9) ?, β=91.709(7)°, V=2217.5(1) ?⁻³, Z=4.Supplementary materials Additional material available from the Cambridge Crystallographic Data Centre (CCDC no. 600927 for [Et₃NH]⁺[(4-MeC₆H₄O)₂PS₂]⁻ comprises the final atomic coordinates for all atoms, thermal parameters, and a complete listing of bond distances and angles. Copies of this information may be obtained free of charge on application to The Director, 12 Union Road, Cambridge CB2 2EZ, UK (fax: +44-1223-336033; email: deposit@ccdc.cam.ac.uk or www:http://www.ccdc.cam.ac.uk).     

First-principles coexistence simulations of supercooled liquid silicon

We perform first-principles coexistence simulations of the low-density and the high-density phases of supercooled liquid silicon and find a negative slope for the coexisting line in the temperature-pressure plane. Electron density maps and electron-localization function plots of the two phases of silicon show marked differences. The calculated differences suggest more localized electrons in the low-density liquid compared to the high-density liquid, coming from an increased population of covalent bonds, which further explain the calculated negative slope in the two phase coexistence regime. This is consistent with the presence of a pseudo-gap in low-density liquid silicon, absent in the high-density liquid which shows a metallic behavior.     

Crystal structures of thecis andtrans isomers of dithiahexahydro[3.3]metacyclophane

Structures of both thecis andtrans isomers of dithiahexahydro[3.3]metacyclophane, ?C₆H₄?CH₂SCH₂?C₆H₁₀?CH₂SCH₂?, have been determined, wherecis andtrans refer to the attachments to the cyclohexane ring. Thecis form crystallizes in the monoclinic space groupP2₁/c witha=8.4299(11)Å,b=21.772(2)Å,c=8.9724(13)Å, β=116.574(11)^o, andZ=4. Thetrans isomer packs into the monoclinic space groupP2₁ witha=8.159(16)Å,b=10.185(5)Å,c=9.558(2)Å, β=112.435(18)^o, andZ=2. The cyclohexane ring of thecis isomer is in the chair conformation, while the cyclohexane of thetrans isomer is found in a twisted boat conformation.     

CTAB与SDBS对碳酸锶粒子生长形态调控及机理研究

以表面活性剂CTAB和SDBS为化学添加剂,采用化学共沉淀法对碳酸锶晶体的生长形态进行调控,成功地制备出了实心的树枝状和花瓣为空心的花状碳酸锶粉体,并用X射线衍射(XRD)、扫描电子显微镜(SEM)和傅里叶变换红外光谱(FT-IR)等分析手段对样品进行了表征;最后重点对化学添加剂可能产生的影响机理进行了初步的探讨.结果表明,CTAB和SDBS在晶体生长的过程中能起到显著的影响作用,两者对粒子分散性能的作用效果相反,而且后者对晶体(013)和(213)晶面表面能降低的贡献明显大于前者.     

Crystal structures of the cis and trans isomers of a tetrathia[3.3.3.3]cyclophane

Both the cis and trans isomers of 3,11,18,26-tetrathiatricyclo[26.2.2.1^5,9.2^13,16.1^20,24] hexatriaconta-5,7,9,20,22,24-hexene have been prepared and structurally characterized. Each of these centrosymmetric tetrathia dimers includes two cyclohexane rings in chair conformations with either 1,4-cis or 1,4-trans bonding and two meta-substituted benzene rings. The cis isomer packs into the monoclinic space group P2₁/a with a = 10.485(3)Å, b = 10.3956(18)Å, c = 14.1343(10)Å, = 105.200(13)°, Z = 2 and refined to an R factor of 0.046. The trans isomer crystallizes in the monoclinic space group P2₁/c with a = 10.7217(12)Å, b = 5.6797(7)Å, c = 25.415(5)Å, = 96.001(12)°, Z = 2 and refined to an R factor of 0.043. In the cis structure each benzene ring faces a cyclohexane ring while in the trans structure the cyclohexane rings face one another.     

Crystal structure of Zn4Na(OH)6SO4Cl·6H2O

The structure of Zn₄Na(OH)₆SO₄Cl·6H₂O, a secondary mineral from Hettstedt, Germany, was determined by single-crystal X-ray diffraction. The crystals are hexagonal,a=8.413(8),c=13.095(24) Å, space group $P\bar 3$ , Z=2. The structure was refined to R=0.0554 and R_w=0.0903 for 970 reflections with I≥3σ(I). The structure can be described as zinc hydroxide layers perpendicular toc, from which sulfates and chlorides extend. The layers are held together by a system of hydrogen bonds involving hexaaquo Na⁺ ions which occupy the interlayer space.     

Synthesis and Crystal Structure of 5-[2-(6-bromonaphthalenyloxymethyl)]-3-(4-morpholinomethyl)-1,3,4-oxadiazole-2(3<Emphasis Type="Italic">H</Emphasis>)-thione

Abstract  The title compound, C₁₈H₁₈BrN₃O₃S, a derivative of 1,3,4-oxadiazole, crystallizes in the triclinic space group P-1 with unit cell parameters a = 6.8731(3), b = 8.9994(4), c = 15.7099(6) ?, α = 92.779(3)°, β = 130.575(3)°, γ = 107.868(4)°, Z = 2. The dihedral angle between the mean planes of the planar naphthyl and morpholine (chair) rings with the planar oxadiazol ring is 50.1(8) and 76.8(6)°, respectively. The planar naphthyl ring is twisted 52.2(5)° with the mean plane of the morpholine ring. A group of four intermolecular close contacts are observed between a bromine atom and hydrogen atoms from the closely packed naphthyl, morpholine and oxy–methyl groups in the unit cell. These molecular interactions in concert with an additional series of π–π stacking interactions that occur between the center of gravity of the two 6-membered rings of the naphthalene group influence the twist angles of each of these three groups. A MOPAC AM1 calculation of the conformation energy of the crystal structure [226.0128(9) kcal] compared to that of the minimum energy structure after geometry optimization [29.9744(1) kcal] reveals a significantly reduced value. The twist angles of the three groups above also change after the AM1 calculation giving support to the influence of both intermolecular C–H···Br short-range interactions and Cg π–π stacking interactions on these angles which therefore play a role in stabilizing crystal packing. Graphical Abstract  Crystal structure of 5-{[(6-bromonaphthalen-2-yl)oxy]methyl}-3-(morpholin-4-ylmethyl)-1,3,4-oxadiazole-2(3H)-thione, C₁₈H₁₈BrN₃O₃S, is reported and its geometric and packing parameters described and compared to a MOPAC computational calculation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

电沉积法制备ZnO纳米棒阵列及其发光特性

本文以掺F的SnO2导电玻璃为基板,以硝酸锌水溶液为电解液,采用三电极恒电位体系电沉积制备ZnO纳米棒阵列,系统考察了硝酸锌浓度和沉积电位等工艺参数对ZnO纳米棒阵列的微观形貌及其发光性能的影响规律.结果表明,硝酸锌浓度和沉积电位对纳米棒阵列的形貌有显著影响,控制适宜的工艺条件可以制备出直径分布均匀、结晶性好且纯度高的六方纤锌矿ZnO纳米棒阵列.荧光光谱分析表明,电沉积制备出的ZnO纳米棒阵列在385 nm附近有一个强荧光发射峰,且发光性能稳定、对纳米棒阵列微观形貌的细微变化不敏感,使其在发光二极管和激光器等领域具有广阔的应用前景.     

Crystal structure of irisolidone from the flowers of Pueraia lobata

Irisolidone (5,7-dihydroxy-6,4′-dimethoxyisoflavone) was isolated from the flowers of Pueraia lobata and its crystal structure was examined by X-ray single crystal diffraction. The crystal structure of irisolidone is monoclinic, space group P2₁/c with a = 15.491(9) ?, b = 7.895(4) ?, c = 13.321(7) ?, β = 110.546(9)° and Z = 4. Hydrogen bonding and aromatic π–π stacking assemble the title compound into a three-dimensional networking structure.