Effects of Doped Elements on Electrochemical Performance of Ni（OH）2 Materials

High energy ball milling(HEBM)method was applied to synthesize Ni(OH)2 with different doped elements substitution for Ni2 .The morphology,structure and electrochemical behavior of prepared powders were studied.The results reveal that all the synthesized Ni(OH)2 particles were in sub-micron sizes and greatly agglomerated.Co-,Mg-,Fe-or Mn-doped Ni(OH)2 was of β-phase with 0.400-0.500 nm crystal interlayer distance,while Al-and Zn-doped products displayed α-phase with larger crystal interlayer spaces.The electrochemical mechanisms of synthesized Ni(OH)2 electrodes were discussed by EIS spectra.The specific capacity of Co-doped Ni(OH)2 is 245 mA·h·g-1,i.e.,60 mA·h·g-1 higher than that of Al-doped electrode,which has the highest discharging platform of a mid-voltage of 1.30 V.     

Hydrothermal Synthesis, Crystal Structure and Electrochemical Properties of Complex Cu（α-Furacrylic acid）2（phen）

The title complex (C26H18CuN2O6,Mr=517.96) has been synthesized by the reac-tion of α-furanacrylic acid with 1,10-phenanthroline (phen) in the solvent mixture of water and methanol. Crystal data: monoclinic,space group C2/c with a =2.2927(4),b=1.01248(18),c=1.05061(18) nm,β=111.188(3)o,V=2.274(7) nm3,Dc=1.513 g/cm3,Z=4,F(000)=1060,μ= 1.007mm?1,R=0.0320 and wR=0.0781. The crystal structural analysis shows that the copper atom is coordinated with four oxygen atoms from two α-furacrylic acids and two nitrogen atoms from 1,10-phenanthroline,giving a distorted octahedral coordination geometry. The result of electroche-mical analysis shows that the electron transfer in the electrode reaction is quasi-reversible.     

Structure of BaGd2（MoO4）4 Crystal

The title compound belongs to monoclinic,space group C2/c with a=5.2694(1),b=12.6659(4),c=19.4108(2) ,β=91.504(2)°,V=1295.06(5) 3,Z=4 and Dc=5.599 g/cm3. The structure of BaGd2(MoO4)4 contains a MoO4 tetrahedron,a distorted GdO8 polyhedron,and Ba2+ ions in a tenfold coordination. The GdO8 polyhedra are linked together through edge-sharing to give a two-dimensional Gd layer. The MoO4 tetrahedra connected to the Gd atoms are capped up and down the Gd layer through common oxygen apices,thus forming a new Gd-Mo layer. Finally,the Gd-Mo layers are held together through bridging BaO10 polyhedra to form a three-dimensional framework. Since the Ba-μ3-O bond has a large average distance of 2.888 ,this structural characteristic will result in a cleavage along the (001) plane.     

Structure and Crystal Growth of Li2Zn2（MoO4）3

Single crystal of Li2Zn2(MoO4)3 has been grown from a flux of Li2MoO4 by the top-seeded solution-growth method,and its structure was refined by the Rietveld method. It belongs to the orthorhombic system,space group Pnma with a=5.1114,b=10.4906 and c=17.6172. Good agreement between the experimental and calculated profile(Rp=6.69%,Rwp=9.73% and Rexp= 6.58%) was reached.     

Growth and Crystal Structure of YbAl3（BO3）4

1 INTRODUCTION With the development of high power InGaAs laser diode (LD) as pump sources, the Yb3+-doped laser crystals have received much attention. Due to the simple energy level structure of the Yb3+ ions, the Yb3+-doped laser crystals have no concentration quenching, and have high quantum efficiency and low quantum defects even at high doping concentration of the Yb3+ ions[1, 2]. Therefore, the Yb3+-doped crystals are good candidates of media in the LD-pumped solid-state laser,…     

Synthesis, Crystal Structure and Electrochemical Properties of the Complex Cd（α-FRA）2（Phen）（H2O）

1 INTRODUCTION The syntheses and structures of carboxyl complex- es have captured the interest of chemists for years due to their potential applications in many fields, such as materials, medicine, molecular electro-che- mistry and biochemistry[1～3]. So far, to the best of our knowledge, cadmium complexes with aromatic carboxylic acid as ligands have been intensively studied[4～7], but those with heterocyclic carboxylic acid as ligands are much less. α-Furoic acid is widely used in orga…     

Synthesis and Crystal Structure of a New Lanthanum（Ⅲ） 4-Cyanobenzoate Complex

A new dinuclear La（Ⅲ） complex [La2（4-cba）4[H（4-cba）2]2（phen）2（H2O）4] （4-Hcba = 4-cyanobenzoic acid and phen = 1,10-phenanthroline） 1 has been synthesized by solvothermal reaction in an ethanol/water mixed solution at 100 ℃ and structurally characterized by singlecrystal X-ray diffraction. Crystallographic data： C88H58La2N12O20, Mr = 1881.28, triclinic P1, a = 7.518（3）, b = 17.033（6）, c = 17.551（6）A, α = 115.333（4）, β = 92.9910（10）, γ = 99.366（5）°, V = 1985.3（12）A^3, Z = 1, Dc = 1.574 g/cm^3, F（000） = 944 μ = 1.145 mm^–1, the final R = 0.0281 and wR = 0.0686 for 6708 reflections with Ⅰ 〉 2σ（I）. In 1, two nine-coordinated La（Ⅲ） ions are connected by two 4-cba ligands in a syn-syn bidentate coordination mode, and the other six 4-cba ligands terminate the La（Ⅲ） ions, resulting in an isolated dinuclear structure. Two different types of intramolecular hydrogen bonds, asymmetrical O-H…O and symmetrical O…H…O, exist in the crystal. The title complex molecules are connected through hydrogen bonds and weak π-π stacking interactions to generate a 2-D layered network. The thermogravimetric analysis of 1 has also been discussed.     

Crystal Structure and Catalytic Properties of Tetrakis（4-hydroxyphenyl）Porphyrinato Manganese （Ⅲ） Chloride （MnTHPPCI）

The crystal structure of meso-tetrakis （4-hydroxyphenyl） porphyrinato manganese chloride （MnTHPPC1） and its supramolecular architecture based on the hydrogen bonds of one counter C1 anion with four hydrogen atoms of four-OH groups from different MnTHPPC1 molecules cooperated by self-assembly of the porphyrin units were first repor-ted. This compound crystallized in the tetragonal space group 14/m with a = 1.39928（7） nm, b = 1.39928（7） nm, c =0.94498（10） nm, V= 1.8503（2） nm^3, and Z =2. As a catalyst, MnTHPPC1 also showed a high catalytic acti-vity in the conversion from 1-naphthylamine （1-NA） to his （4-oxo-benzo-2-cyclohexen-l-yl） amine （BOBCHA） v/a oxidative coupling under mild conditions.     

Cu~(2+)掺杂LiFePO_4的制备及其电化学性能

应用固相反应法合成LiFePO4及掺杂Cu2+的LiFePO4,以XRD、XPS表征样品的结构及Fe存在的价态.发现掺杂少量的Cu2+未能改变LiFePO4材料的结构特征以及Fe2+的化学状态,但是Cu2+的掺杂使得LiFePO4材料的晶胞体积变小.充放电测试结果表明少量Cu2+的掺杂能显著地提高LiFePO4材料的大倍率输出能力,LiCu0.02Fe0.98PO4,其1C放电容量可达130 mAh/g以上,较掺杂前提高了20%左右.     

钽离子掺杂对LiFePO4 / C物理和电化学性能的影响

采用PAM(聚丙烯酰胺)模板-溶胶凝胶法在惰性气氛下合成钽掺杂的LiFePO₄/C复合正极材料，考察了钽对目标化合物的物理和电化学性能的影响。研究结果表明，0.33C的电流下充放电时，掺杂前后第2个循环的放电容量分别为138.6 mAh·g^-1和155.5 mAh·g^-1，循环20次后容量为141 mAh·g^-1和156 mAh·g^-1。电化学交流阻抗表明，掺杂后的材料阻抗R_ct从180 Ω减小到120 Ω。振实密度比掺杂前提高0.312 g·cm^-3。     

锰离子掺杂对LiCoPO4性能的影响

应用溶胶-凝胶法合成了锰掺杂的LiCoPO4正极材料.X射线衍射、扫描电镜和循环伏安等电化学测试表明,少量锰离子掺杂不影响LiCoPO4的晶格结构,且明显改善了LiCoPO4正极材料电化学性能.锰掺杂量为1%时得到的LiMn0.01Co0.99PO4正极材料具有最好的电化学性能,以0.1C倍率放电时,首次放电比容量可达130.6 mAh/g.     

Theoretical study on the Co~(2+)OH_2/Co~(3+)OH_2 electron transfer reactivity

This paper presents a contact distance dependence analysis scheme and an ab initio calculation application for the electron transfer (ET) reactivity of Co2+OH2/Co3+OH2 reacting pair. The applicability of these schemes and the corresponding models has been discussed. The contact distance (Rcoco) dependence of the relevant quantities has been analyzed. The results indicate that the activation energy from the accurate PES method agrees well with that from the anharmonic potential method, and they are obviously better than that from the harmonic potential method. The pair distribution function varies from 10~(-2) to 10~(-5) along with Rcoco changing from 1.20 to 0.35 nm. The coupling matrix element exponentially decays along with the increase of Rcoco, and the effective electronic coupling requires Rcoco smaller than 0.75 nm. In the range from 0.50 to 0.75 nm for Rcoco, the corresponding electronic transmission coefficient falls within 1.0-10~(-6). The local ET rate also exponentially decays along with the incre     

Zr4+离子掺杂对LiFePO4结构及电化学性能的影响

应用固相反应法于惰性气氛下合成掺Zr的L iFePO4正极材料.考察Zr4+掺杂浓度对于目标化合物结构及其电化学性能的影响.XRD,交流阻抗和恒流充放电测试等实验表明,少量的Zr4+掺杂并未影响目标材料产物的结构,反而有利于降低L iFePO4电荷转移反应的阻抗,从而有利于克服该电极过程中的动力学限制.该正极材料表现出优良的倍率放电性能,在0.1C倍率下,L i0.99Zr0.01FePO4的首次放电比容量达135.6mAh.g-1.30次循环后,容量衰减仅3.8%.     

水热还原法合成LiFePO4及电化学性能研究

以可溶性三价铁盐FeCl3为铁源,Fe粉作还原剂,应用水热还原法合成LiFePO4.XRD、红外光谱及SEM形貌表征表明,在水热条件下,铁粉能完全将三价铁还原为二价铁,得到单一相LiFePO4,且其颗粒团聚形成花簇状;而LiFePO4经过葡萄糖的热解包覆碳生成LiFePO4/C后,颗粒转变似球状.电化学性能测试结果表明,虽然单相LiFePO4的放电容量很低,但LiFePO4/C却表现出良好的倍率性能和循环稳定性.     

纳米级LiFePO_4材料的水热模板法合成及其性能研究

采用水热模板法合成纳米级LiFePO4材料,改变水热反应中表面活性剂(十六烷基三甲基溴化铵)的比例控制样品颗粒生成的大小.SEM测试表明,合成的LiFePO4晶粒尺寸与表面活性剂的配比密切相关,范围在几十到几百nm之间.充放电试验表明,合成的纳米级LiFePO4材料电极具有优良的电化学性能,其0.1C放电最高比容量可达150 mAh/g,而1C和2C放电比容量也分别有140 mAh/g和126 mAh/g.     

Nd3+掺杂对LiFePO4结构及电化学性能的改善

采用两步加热高温固相法合成了掺杂Nd3+的LiFe1-xNdxPO4/C复合材料(x=0,0.01,0.02,0.04,0.06,0.08).用TG-DSC对前驱体进行分析和SQUID(超导量子干涉仪)对样品中Fe3+的磁性测定,优化了合成工艺条件;采用XRD、FE-SEM、EDS等方法分析了样品的结构并对其电化学性能进行了测试.结果表明:LiFe1-xNdxPO4/C复合材料具有橄榄石型结构;当Nd3+的掺杂量6%(物质的量分数)、煅烧温度700℃、煅烧时间16h时,样品在0.2C(1C=170.0mA·g-1)电流密度下的最大放电比容量可达165.2mAh·g-1,循环100次后的容量保持率仍为92.8%,在1C、2C、5C下的最大放电比容量分别为146.8、125.7和114.8 mAh·g-1.通过测定样品在不同较低倍率下的放电比容量,采用外推法得出制备样品的实测理论比容量为168.7 mAh·g-1.     

焙烧温度对合成LiFePO4的产物组成和电化学性能的影响

以FePO4为前驱体, 采用碳热还原法合成了LiFePO4/C复合正极材料; 通过TG-DTA、FTIR、XRD 等技术研究了反应历程, 分析了不同焙烧温度下产物的组成及杂相存在的原因, 并测试了其电化学性能. 研究表明, 300 ℃下LiFePO4已作为主要的相存在, 显示了较低的成相温度; 300、400、500 ℃下样品中存在一定量的杂相Li3PO4和Fe2O3, 600 ℃得到纯相的LiFePO4, 而在700 ℃下出现了焦磷酸盐Li4P2O7, 这些杂相的存在影响了其电化学性能, 600 ℃样品具有最佳的电化学性能, 其在0.1C下首次放电容量达146 mAh·g-1, 循环15 次后容量还保持为141 mAh·g-1.     

快离子导体Li3V2(PO4)3包覆LiFePO4的结构和性能

通过机械活化将快离子导体Li3 V2(PO4)3包覆在LiFePO4 表面, 制备了性能优异的复合正极材料9LiFePO4@Li3 V2(PO4)3. 用XRD, SEM, HRTEM, EDS和电化学测试等手段研究了材料的物理化学性能. 结果表明, 包覆后的材料含有橄榄石结构的LiFePO4、单斜晶系的Li3 V2(PO4)3 和正交晶系的Li3 PO4; LiFePO4颗粒表面包覆了一层Li3 V2(PO4)3, 且部分V3+进入LiFePO4晶格内部, 使其晶格参数减小, 包覆后的LiFePO4的交换电流密度和锂离子扩散系数均提高了1个数量级. 电化学测试结果表明, 包覆后的LiFePO4的倍率性能及循环性能都得到显著改善, 在1C和2C倍率下, 包覆后的LiFePO4的首次放电比容量较包覆前分别提高了34.09%和78.97%, 经150次循环后容量保持率分别提高了27.77%和65.54%; 并且5C时容量为121.379 mA·h/g(包覆前LiFePO4在5C下几乎没有容量), 循环350次后的容量保持率高达94.03%.