焙烧温度对Li[Mn1/3Ni1/3CO1/3]O2结构及电化学性能影响

采用碳酸盐共沉淀法制备了Li[Mn1/3Ni1/3Co1/3]O2,研究了前驱体的焙烧温度对材料结构和电化学性能的影响.XRD测试结果表明,800℃下焙烧得到的样品具有较好的层状结构和较低的阳离子混排程度.SEM测试表明合成材料具有球状形貌,平均粒径可达5μm,组成它的一次颗粒粒径平均为200nm.在2.8～4.3V(vs.Li/Li+)0.2C条件下进行充放电测试,800℃下合成的样品的首次放电比容量最高(159.06mAh·g-1),容量损失最小,循环50次后能保持初始放电比容量的95.7;.EIS分析结果表明,800℃焙烧的样品的电化学活性最好.     

以酚醛树脂为碳源合成锂离子电池正极材料Li3V2 (PO4)3/C

以酚醛树脂为碳源,分别采用了固相法和溶胶凝胶法合成了锂离子电池正极材料Li3V2(PO4)3/C.结果表明,高分子材料酚醛树脂是一种优良的碳源材料,其热解后得到的导电网络能够有效的提高Li3V2(PO4)3的电化学性能;两种试样的充放电曲线和交流阻抗图谱体现出了试样良好的可逆性,其极化程度很低,电荷转移电阻小;而相对于固相法来讲,溶胶凝胶法和表面活性剂CTAB(十六烷基三甲基溴化铵)的共同作用能够有效的将颗粒粒径控制在纳米级别.用这种方法合成的试样在15 C下充放电比容量也能高于90 mAh/g,5C倍率下循环50次比容量无衰减,证明了以酚醛树脂为碳源并采用溶胶凝胶法合成的试样具有很好的倍率性能与循环性能.     

锂离子电池正极材料Li(Ni1/3Co1/3Mn1/3)O2电极过程动力学研究

采用共沉淀法制备锂离子电池正极材料Li(Ni1/3Co1/3Mn1/3)O2,通过循环伏安法和电化学交流阻抗分析,探讨了锂离子在LiNi1/3Co1/3Mn1/3O2中嵌入和脱出的机制。循环伏安测试结果表明,LiNi1/3Co1/3Mn1/3O2材料结构中不存在John-teller效应,从而抑制了电极材料和电解液之间的副反应。电化学交流阻抗测试结果表明,随着电压的升高Rct(电荷转移电阻)值逐渐减小,而随着循环次数的增加Rct值逐渐增大。     

3LiMnPO4·Li3V2（PO4）3正极材料的制备及其电化学性能研究

以五氧化二钒干凝胶、碳酸锰、磷酸二氢铵、碳酸锂、乙炔黑为原料,采用固相法在相对较低的温度条件下合成了x Li Mn PO4·y Li3V2(PO4)3锂离子电池复合正极材料。采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和表面形貌进行表征。结果表明,750℃下烧结15 h合成的3Li Mn PO4·Li3V2(PO4)3为结晶良好的两相结构,颗粒粒径较小且分布比较均匀,其在室温、0.2 C倍率下首次充放电容量分别为144.8 m Ah/g和139.8 m Ah/g,循环50次后容量为130.5 m Ah/g。     

负极材料Li4Ti5O12的制备与性能研究

利用纳米二氧化钛(P25)粉为钛源,Li2CO3为锂源,采用固相法及高能球磨法制备亚微米级尖晶石Li4Ti5O12.将Li4Ti5O12与碳纳米管(CNTs)制备成复合电极作为工作电极与锂片组成电池进行电化学性能测试.通过SEM,XRD等表征材料形貌、结构及粒径分布,通过充放电测试表征其电化学性能.结果表明,在800℃合成温度及8h合成时间制备条件下可以得到小尺寸且颗粒均匀的亚微米晶体Li4Ti5O12,且合成的产物电化学性能最佳.在800℃及8h合成条件下,产物首次充放电容量分别为188.0 mAh/g和189.1 mAh/g,首次充放效率为99.4％,且具有良好的可逆性.     

溶胶-凝胶法合成3LiMnPO4·Li3V2(PO4)3及其电化学性能研究

以柠檬酸为络合剂,聚乙二醇(PEG)为表面活性剂,偏钒酸铵、乙酸锰、磷酸二氢铵、氢氧化锂为原料,采用溶胶-凝胶法合成了xLiMnPO4·yLi3V2(PO4)3锂离子电池复合正极材料.采用X射线衍射(XRD)、扫描电镜(SEM)对其晶体结构和微观形貌进行表征,结果表明在700℃下烧结15 h合成的3LiMnPO4·Li3V2(PO4)3为结晶良好的两相结构,颗粒粒径相对较小且分布均匀.电化学性能研究表明,3LiMnPO4·Li3V2(PO4)3在室温0.2C倍率下首次充放电容量分别为148.2 mAh/g和141.5 mAh/g,循环50次后放电容量为136.7 mAh/g.     

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;.     

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;.     

Sr2+置换改性Ca0.25(Li1/2Sm1/2)0.75TiO3陶瓷的微波介电性能研究

采用固相法制备了(Ca1-xSrx)0.25(Li1/2Sm1/2)0.75TiO3(CSLST-x)( x= 0～1/10)系列微波介质陶瓷材料,研究不同含量的Sr2+含量对该体系的相组成、烧结性能和微波介电性能影响.在x=1/22～1/10范围内,Sr2+的掺杂不会改变晶体的结构;在1175～1200 ℃烧结时,相同烧结温度下随着Sr2+含量的增加,介电常数εr增大,无载品质因数与谐振频率乘积Qf值降低;置换离子Sr2+的添加使该体系的烧结温度降低了近200 ℃,并保持良好的微波介电性能.其中,x=1/16的CSLST陶瓷在1200 ℃烧结,保温5 h时具有较好的微波介电性能:εr=97.2,Qf=2490 GHz,τf =14.74 ppm/℃.     

[001]c极化0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3单晶中声表面波传播特性

利用室温下弛豫铁电单晶0.93Pb(Zn1/3Nb2/3)O3-0.07PbTiO3的材料参数,计算了[001]c极化PZN-7; PT晶体中的声表面波传播特性.结果表明,[001]c极化0.93Pb(Zn1/3Nb2/3) O3-0.07PbTiO3单晶具有明显优于传统压电材料的声表面波特性.0.93Pb(Zn1/3Nb2/3) O3-0.07PbTiO3单晶的声表面波特性随着传播方向发生明显的变化.综合考虑晶体的三种声表面波特性,发现Y切型晶体的综合声表面波性能最好,声表面波机电耦合系数k2值较大,能流角和声表面波自由表面相速度值较小,有望应用于下一代低频声表面波设备中.     

Hydrothermal Synthesis,Crystal Structure,and Photoluminescent Properties of Li[UO2(CH3COO)3]3[Co(H2O)6]

Crystallography Reports - Single crystal of Li[UO2(CH3COO)3]3[Co(H2O)6] was prepared and found to crystallize in the monoclinic crystal system in the sp. gr. C2/c, with Z = 2, and unit cell...     

Structure and conformation of a nickel complex: {2‐Hydroxo‐3‐piperidine‐1‐yl‐methyl‐N,N′(bis‐5‐bromobenzylpropylenediimine)nickel(II)perchlorate}

The title compound, a nickel complex [C₂₃H₂₆N₃O₂Br₂Ni.(ClO₄)] (CCDC 199520) crystallizes in triclinic space group P with the cell parameters a = 10.2560(4), b = 10.8231(4), c = 12.0888(5)Å, α = 99.404(1), β = 99.780(1), γ = 92.252(1)° and V = 1301.49(9)ų. The structure was solved by Patterson method and refined by full‐matrix least‐squares procedures to a final R = 0.0497 using 6287 observed reflections. In the complex, the piperidine ring takes chair conformation and the geometry around the Ni ion is slightly distorted square planar. The dihedral angle between the planes [N‐Ni‐N and O‐Ni‐O] is 9.4(1)°. The chelate ring containing both the nitrogen atoms adopts twisted boat conformation. The molecules in the crystal are stabilized by N‐H…O and C‐H…O types of hydrogen bonds in addition to a C‐H…π interaction. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Synthesis,characterization and crystal structure of a novel Ni(II) coordination polymer with dipyrido[3,2‐a:2′,3′‐c]phenazine and 4,4′‐oxy(bisbenzoate)

A novel coordination polymer, [Ni(dppz)(oba)(H₂O)]·0.5H₂O (dppz = dipyrido[3,2‐a:2′,3′‐c]phenazine and oba = 4,4′‐oxy(bisbenzoate)) has been synthesized through hydrothermal method and characterized by IR, and single‐crystal X‐ray diffraction. It crystallizes in monoclinic, space group C2/c with a = 23.163(5), b = 18.211(4), c = 14.460(3) Å, α = γ = 90°, β = 100.45(3)°, V = 5998(2) ų, Z = 2. The structure was solved by direct methods and refined to R = 0.0866 (wR₂ = 0.1836). The compound exhibits interesting one‐dimensional chain structures, which are further stacked through π‐π interactions to form supramolecular double chains. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal structure and infrared and electronic spectra of some divalent first series transition metal pentacyanonitrosylmanganates (I)

Structural and infrared and electronic spectroscopic studies of the coordination polymers corresponding to the compounds of simplest formulas M ₃ ^II [Mn(CN)₅NO]₂·nH₂O (M=Mn, Co, Ni, Cu, Zn, andn=8–16) are reported and discussed in comparison with the corresponding nitroprussides. These polymers have a typical face centered cubic unit cell containing 1 1/3 formula units, except for M=Mn where the crystal system is orthorhombic.     

The Characteristics of EDTA's Transition Metal Complexes (III) The d-d Transition Spectrum and Structure Characteristic of [Pb.Ni(HEDTA)H2O] Cl Crystal

The electronic absorption spectrum of crystals of the title compound [Pb.Ni(HEDTA) H₂O] Cl was recorded and discussed quantitatively. Using ligand field theory and the radial wave function of bound Ni(II) ion, the d-d transition energy levels of crystals of [Pb.Ni(HEDTA) H₂O] Cl, Ca [Ni(EDTA)] · 4H₂O, [Li.Ni(HEDTA) H₂O], [NiH₂EDTA)H₂O] were calculated. The different structure characteristics of EDTA's metal complexes are evidently shown in their d-d transition spectra.     

Crystal structure of 3‐(3‐nitrophenylhydrazonocarbonyl)‐(1H)‐1,2,4‐triazole

The title compound, C₁₀H₈N₆O₃, was synthesized by the reaction of 3‐(1H)‐1,2,4‐triazole hydrazine with 3‐nitrobenzaldehyde in ethanol. The single crystal structure has been determined by X‐ray analysis. The crystal belongs to monoclinic system, space group p2₁/c with cell constant, a = 8.0214(17) Å, b = 17.334(4) Å, c = 8.9070(18) Å, V= 1179.4(4) ų. An intramolecular N—H...O and N—H…N hydrogen bond are observed between the ‐NH group with O atom of the carbonyl group and the ‐NH group with N atom. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Structural investigation of gallium oxide (β-Ga2O3) nanowires grown by arc-discharge

Gallium oxide nanowires were synthesized by electric arc discharge of GaN powders mixed with a small amount of Ni and Co. The crystal structure of nanowires was determined by multi-channel X-ray diffractometry (MC-XRD), FT-Raman spectroscopy and transmission electron microscopy (TEM). The analyzed results clearly show that the synthesized nanowires are monoclinic gallium oxide (β-Ga₂O₃). Final morphology and microstructure of β-Ga₂O₃ nanowires were changed depending on the presence of the transition metals into the nanowires. The β-Ga₂O₃ nanowires grown by the assistance of transition metals demonstrate a smooth edge surface while containing twin defects at the center. The transition metals have enhanced the step growth of nanowires. However, in the case of the β-Ga₂O₃ nanowires, where the transition metals are not shown on the surface, the nanowires demonstrate rather thin and long shapes with amorphous gallium oxide layers on the nanowire surface.     

Synthesis and crystal structures of nitratocobaltates Na2[Co(NO3)4], K2[Co(NO3)4], and Ag[Co(NO3)3] and potassium nitratonickelate K2[Ni(NO3)4]

The cobalt(II) and nickel(II) nitrate complexes with an island structure (Na₂[Co(NO₃)₄] (I) and K₂[Co(NO₃)₄] (II)] and a chain structure [Ag[Co(NO₃)₃] (III) and K₂[Ni(NO₃)₄] (IV)] are synthesized and investigated using X-ray diffraction. In the anionic complex [Co(NO₃)₄]^2? of the crystal structure of compound I, the Co coordination polyhedron is a twisted tetragonal prism formed by the O atoms of four asymmetric bidentate nitrate groups. In the anion [Co(NO₃)₄]^2? of the crystal structure of compound II, one of the four NO₃ groups is monodentate and the other NO₃ groups are bidentate (the coordination number of the cobalt atom is equal to seven, and the cobalt coordination polyhedron is a monocapped trigonal prism). The crystal structures of compounds III and IV contain infinite chains of the compositions [Co(NO₃)₂(NO₃)_2/2]^? and [Ni(NO₃)₃(NO₃)_2/2]^2?, respectively. In the crystal structure of compound III, seven oxygen atoms of one monodentate and three bidentate nitrate groups form a dodecahedron with an unoccupied vertex of the A type around the Co atom. In the crystal structure of compound IV, the octahedral polyhedron of the Ni atom is formed by five nitrate groups, one of which is terminal bidentate. The data on the structure of Co(II) coordination polyhedra in the known nitratocobaltates are generalized.     

Two Co/Ni(II)-Based Coordination Polymers for Degradation of Dyes

Crystallography Reports - Two isostructural Co/Ni(II)-based coordination polymers, namely, {[Co1/2(bpba)(H2O)]?2H2O}n (1) and {[Ni1/2(bpba)(H2O)]?2H2O}n (2), where Hbpba = 3,5-bis...