Synthesis and properties of cathode materials xLi2MnO3 x (1-x)LiMn1/3Ni1/3Co1/3O2 for Li-ion batteries.

Lithium- and manganese-rich layered electrode materials, represented by the general formula xLi2MnO3 x (1-x)LiMO2 in which M is Mn, Ni, and Co, are of interest for both high-power and high-capacity lithium ion batteries. In this paper, a series of nano-sized materials based on the xLi2MnO3 x (1-x)LiMn1/3Ni1/3Co1/3O2 (x = 0, 0.2, 0.4, 0.6) as a cathode material for lithium batteries were synthesized by the sol-gel method, citric acid as a chelating agent. Its structural and electrochemical properties were investigated using X-ray diffractometry, scanning electron microscopy, galvanostatic charge-discharge test. Differences between electrochemical and chemical activation of the Li2MnO3 component are discussed. The results indicated that well-ordering layered xLi2MnO3 x (1-x)LiMn1/3Ni1/3Co1/3O2 (x = 0, 0.2, 0.4, 0.6) cathode materials were successfully prepared with alpha-NaFeO2 typical crystal. It is found that the changes in compositional, crystal structure and electrochemical performance depend highly on the different values of x. The charge-discharge capacity and cycle number plots confirm unequivocally that the Li2MnO3 component serves to stabilize LiMn1/3Ni1/3Co1/3O2 electrodes to electrochemical cycling. The study emphasizes that, for high values of x, a relatively small LiMn1/3Ni1/3Co1/3O2 concentration stabilizes a layered Li2MnO3 electrode to reversible lithium insertion and extraction. The composition x = 0.2 leads to the best electrochemical performance cathode material with high capacity of 253 mA h/g and high-rate property.

Growth of "waist" ZnO twin rods through hydrothermal synthesis.

The factors that govern the deposition and structure of "waist" ZnO twin rods from aqueous solution through hydrothermal synthesis were discussed in details. Pencil-like ZnO hexagonal twin rods were obtained in Zn(2+) + HMTA system on ITO glass substrates with ZnO buffer layer deposited in advance. As a contrast, a series of experiments were preceded with TBAB or on bare Cu sheet, Zn sheet, and Al sheet to research lattice-match influences on ZnO nucleation. A series of "waist" ZnO hexagonal twin rods were synthesized and the morphology of each "waist" was shown. The forming of different waists results from the different lattice-match effects between substrates and ZnO crystal. We demonstrated ZnO hexagonal twin rods synthesis on Cu, Al, Zn sheet by normal hydrothermal synthesis and revealed different forming schemes of these varying "waists" of the twin structures. On the basis of our research, not only some new ways of synthesizing ZnO twin rods were proposed but a new idea of applying metal to nano-devices used in piezoelectric area.

Shape-controlled synthesis of ZnO microstructures: the effects of inorganic shape directing and pH altering agents.

In this work, shape-controlled synthesis of zinc oxide (ZnO) microstructures were demonstrated using liquid-phase route utilizing zinc acetate hydrate as zinc ion precursor and ammonia as pH buffering agent and source for zinc-ammonia complexes. Glass substrate coated with indium tin oxide layer was used as the growth substrate. Zinc-ammonia complex was thought of as the component of growth for ZnO crystals. Inorganic shape-directing agents, instead of organic ones were used in this study e.g., trisodium citrate or aluminum nitrate hexahydrate. The effect of pH altering agent e.g., sodium hydroxide towards the crystal structure was also probed. Without shape-directing agents, the resultant ZnO crystals exhibited multilayer petals flower shape with uniform size (e.g., diameter of -2.5 microm). Adding trisodium citrate, led to the formation of burger crystals with uniform size (e.g., height of -200 nm and diameter of -800 nm). Adding aluminum nitrate hexahydrate resulted in the formation of hexagonal disk with wide variation in size (diameter varied between -0.8 to 4 microm). The addition of sodium hydroxide, strong base, altered the pH into high value very rapidly in the beginning of the synthesis and caused faster nucleation rate in a NaOH containing solution with respect to that in a NH3 solution. In this case, crystals with different morphology are obtained, e.g., dot like, monopetal-flower like and octahedron like. The detailed processes pertaining for each case were explained in this work.

Aluminium electrodeposition in chloroaluminate ionic liquid.

An efficient microwave enhanced synthesis of ambient temperature chloroaluminate ionic liquid ([EMIM]Br) that preceeds reaction of 1-methylimidazolium with bromoethane in a closed vessel, was described in our work. The reaction time was drastically reduced as compared to the conventional methods. The electrochemical techniques of impedance spectroscopy, cyclic voltammetry and chronoamperometry were used to investigate the mechanism of Al electrodeposition from 2:1 (molar ratio) AlCl3/[EMIM]Br ionic liquid at room temperature. Results indicated that Al electrode- position from this ionic liqud was a quasi-reversible process, and the kinetic complications during the reaction was probably attributed to the electron transfer or mass transport cooperative controlled processes, instantaneous nucleation with diffusion-controlled growth was also investigated. Electrodepositon experiment was conducted using constant current density of 40 mA·cm(-2) for 20 minutes at room temperature and the qualitative analysis of the deposits were performed using X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and energy dispersive spectroscope (EDS). The deposits obtained on copper cathode were dense and compact and most Al crystal shows granular structure spherical with high purity.

Recovery of iron from cyanide tailings with reduction roasting-water leaching followed by magnetic separation.

Cyanide tailing is a kind of solid waste produced in the process of gold extraction from gold ore. In this paper, recovery of iron from cyanide tailings was studied with reduction roasting-water leaching process followed by magnetic separation. After analysis of chemical composition and crystalline phase, the effects of different parameters on recovery of iron were chiefly introduced. Systematic studies indicate that the high recovery rate and grade of magnetic concentrate of iron can be achieved under the following conditions: weight ratios of cyanide tailings/activated carbon/sodium carbonate/sodium sulfate, 100:10:3:10; temperature, 50 °C; time, 60 min at the reduction roasting stage; the liquid to solid ratio is 15:1 (ml/g), leaching at 60 °C for 5 min and stirring speed at 20 r/min at water-leaching; exciting current is 2A at magnetic separation. The iron grade of magnetic concentrate was 59.11% and the recovery ratio was 75.12%. The mineralography of cyanide tailings, roasted product, water-leached sample, magnetic concentrate and magnetic tailings were studied by X-ray powder diffraction (XRD) technique. The microstructures of above products except magnetic tailings were also analyzed by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS) to help understand the mechanism.

Investigation of solution chemistry effects on sorption behavior of Cu(II) on ZSM-5 zeolite.

The sorption of Cu(II) from an aqueous solution using ZSM-5 zeolite was investigated by batch technique under ambient conditions. Sorption was investigated as a function of pH, ionic strength, foreign ions, humic substances, and temperature. The results indicate that the sorption of Cu(II) on ZSM-5 zeolite is strongly dependent on pH. Sorption is dependent on ionic strength at low pH, but independent of ionic strength at high pH values. The presence of humic/fluvic acid (HA/FA) enhances the sorption of Cu(II) on ZSM-5 zeolite at low pH values, and reduces Cu(II) sorption at high pH values. Sorption isotherms were well simulated by the Langmuir model. Thermodynamic parameters (i.e., deltaH0, deltaS0 and deltaG0) for the sorption of Cu(II) were determined from temperature-dependent sorption isotherms at 293.15, 313.15, and 333.15 K, respectively. Results indicate that the sorption process of Cu(II) on ZSM-5 zeolite is spontaneous and endothermic.

Study of 6³Ni adsorption on NKF-6 zeolite.

The adsorption of 6³Ni from aqueous solutions using NKF-6 zeolite was investigated by a batch technique under ambient conditions. The adsorption was investigated as a function of contact time, pH, ionic strength, foreign ions, humic substances (FA/HA) and temperature. The kinetic adsorption was well described by the pseudo-second-order rate equation. The adsorption of 6³Ni on NKF-6 zeolite was strongly dependent on pH and ionic strength, and the adsorption of 6³Ni increased with increasing NKF-6 zeolite content. At low pH values, the presence of FA enhanced the adsorption of 6³Ni on NKF-6 zeolite, but the presence of HA had no drastic effect. At high pH values, the presence of FA or HA decreased the adsorption of 6³Ni on NKF-6 zeolite. The adsorption isotherms were well represented by the Langmuir model. The thermodynamic parameters (i.e., ΔH(0), ΔS(0)and ΔG(0)) for the adsorption of 6³Ni were determined from the temperature dependent isotherms at 293.15, 313.15 and 333.15 °K, respectively, and the results indicate that the adsorption reaction was favored at high temperature. The results suggest that the adsorption process of 6³Ni on NKF-6 zeolite is spontaneous and endothermic.

Impact of environmental conditions on the sorption behavior of Pb(II) in Na-bentonite suspensions.

In this study, a local bentonite from Lin'an county (Zhejiang province, China) was converted to Na-purified form and the Na-bentonite sample was characterized by using FTIR and XRD to determine its chemical constituents and micro-structure. The removal of lead from wastewaters by Na-bentonite was studied as a function of various environmental parameters such as contact time, pH, ionic strength, foreign ions, humic substances and temperature under ambient conditions. The results indicated that the sorption of Pb(II) on Na-bentonite was strongly dependent on pH and ionic strength. The Langmuir, Freundlich and D-R models were used to simulate the sorption isotherms of Pb(II) at three different temperatures of 298, 318 and 338 K. The thermodynamic parameters (ΔH°, ΔS° and ΔG°) calculated from the temperature dependent sorption isotherms indicated that the sorption process of Pb(II) on Na-bentonite was endothermic and spontaneous. At low pH, the sorption of Pb(II) was dominated by outer-sphere surface complexation and ion exchange with Na(+)/H(+) on Na-bentonite surfaces, whereas inner-sphere surface complexation was the main sorption mechanism at high pH. From the experimental results, it is possible to conclude that Na-bentonite has good potentialities for cost-effective disposal of lead bearing wastewaters.

catena-Poly[[bis-(p-toluene-sulfonato-κO)palladium(II)]bis-(µ-1,3-di-4-pyridylpropane-κN:N')].

In the title compound, [Pd(C(7)H(7)O(3)S)(2)(C(13)H(14)N(2))(2)](n), the metal ion, located on a twofold rotation axis, exhibits a slightly distorted octa-hedral coordination environment, with bond angles that deviate by at most 2.2° from an ideal geometry, completed by two O atoms from two deprotonated p-toluene-sulfonic acid ligands and four N atoms from four 1,3-di-4-pyridylpropane ligands. One of the sulfonate O atoms is disordered over two positions [ratio 0.70 (5):0.30 (5)].

Terephthalic acid-4,4'-bipyridine (2/1).

In the title compound, 2C(8)H(6)O(4)·C(10)H(8)N(2), the 4,4'-bipyridine mol-ecule is located on an inversion centre. In the crystal structure, strong inter-molecular O-H⋯N hydrogen bonds between the terephthalic acid and 4,4'-bipyridine mol-ecules lead to the formation of chains with graph-set motif C(2) (2)(8) along the diagonal of the bc plane.

Bis(ethano-lato-κO)(5,10,15,20-tetra-phenyl-calix[4]pyrrole)manganese(III) hexa-fluoro-phosphate.

The title compound, [Mn(C(2)H(5)O)(2)(C(44)H(28)N(4))]PF(6), was synthesized from manganese(III) 2,4-penta-nedionate and 5,10,15,20-tetra-phenyl-calix[4]pyrrole by a hydro-thermal reaction. The Mn(III) atom is located on an inversion centre and the asymmetric unit comprises one half-formula unit. The Mn(III) ion is hexa-coordinated by four N atoms from one 5,10,15,20-tetra-phenyl-calix[4]pyrrole ligand and two O atoms from two deprotonated ethanol mol-ecules. The equatorially located atoms (the Mn and four N atoms) are planar. The dihedral angles between the planes of the phenyl rings and the equatorial plane are 53.3 (2) and 81.8 (2)°. One hexa-fluoro-phosphate anion balances the charge.

catena-Poly[[(2-{1-[2-(2-amino-ethyl-amino)ethyl-imino]-eth-yl}-5-methoxy-phenolato-κN,N',N'',O)copper(II)]-µ-nitrato-κO:O'].

In the title compound, [Cu(C(13)H(20)N(3)O(2))(NO(3))](n), the Cu(II) atom is chelated by the Schiff base ligand via three N atoms and one O atom lying in an approximate square plane (r.m.s. deviation = 0.04 Å). The complex mol-ecules are linked into a polymeric chain by bridging nitrate anions, forming axial Cu-O bonds of 2.535 (6) and 2.676 (7) Å, completing a distorted octa-hedral coordination geometry. The NH groups of the ligand form hydrogen bonds to the nitrate anions.