Tungsten and phosphate polyanion co-doping of Ni-ultrahigh cathodes greatly enhancing crystal structure and interface stability

The Ni-ultrahigh cathode material is one of the best choices for further increasing energy-density of lithium-ion batteries(LIBs),but they generally suffer from the poor structure stability and rapid capacity fade.Herein,the tungsten and phosphate polyanion co-doped LiNi_(0.9)Co_(0.1)O_(2)cathode materials are successfully fabricated in terms of Li(Ni_(0.9)Co_(0.7))_(1-x)W_(x)O_(2-4y)(PO_(4))_(y) by the precursor modification and subsequent annealing.The higher bonding energy of W—O(672 kJ·mol^(-1))can extremely stabilize the lattice oxygen of Ni-rich oxides compared with Ni—O(391.6 kJ·mol^(-1))and Co—O(368 kJ·mol^(-1)).Meanwhile,the stronger bonding of Ni—(PO_(4)^(3-))vs.Ni—O could fix Ni cations in the transition metal layer,and hence suppressing the Li/Ni disorder during the charge/discharge process.Therefore,the optimized Li(Ni_(0.9)Co_(0.1))_(0.99)W_(0.01)O_(1.96)(PO_4)_(0.01)delivers a remarkably extended cycling life with 95.1%retention of its initial capacity of 207.4 mA·h·g^(-1)at 0.2 C after 200 cycles.Meantime,the heteroatoms doping does not sacrifice the specific capacity even at different rates.

Synthesis, Crystal Structure and Thermal Stability of a New Binuclear Cu(Ⅱ) Complex with 2-Benzoylbenzoic Acid as the Ligand

A new complex Cu2（o-C6H5COC6H5COO）4（C10H8N2）2（H2O）2 with 2-benzoylben- zoic acid and 2,2′-bipyridine as ligands has been synthesized in mixed methanol and water solvent. Crystal data are as follows： monoclinic, space group Co, a = 14.0133（14）, b = 16.0409（16）, c = 30.372（3） A, β = 100.8950（10）°, V = 6704.1（12） A3, Dc = 1.364 g/cm3, Z = 8,μ（MoKa） = 0.704 mml, F（000） = 2840, the final R= 0.0552 and wR = 0.1431. In the crystal structure, the whole molecule consists of two copper ions, four 2-benzoylbenzoic acid molecules, two 2,2′-bipyridine molecules and two water molecules. Each central copper ion is coordinated with two nitrogen atoms from one 2,2′-bipyridine molecule and three oxygen atoms from two 2-benzoylbenzoic acids and one water molecule, respectively, giving a distorted tetragonal pyramidal geometry. Thermal stability properties of the complex were investigated.

Stability of Crystal Growth Face and Dissolution Face in Crystallization from Solution under Microgravity

The stability of the shapes of crystal growth face and dissolution face in a two-dimensional mathematical model of crystal growth from solution under microgravity is studied. It is proved that the stable shapes of crystal growth face and dissolution face do exist, which are suitably shaped curves with their upper parts inclined backward properly.The stable shapes of crystal growth faces and dissolution faces are calculated for various values of parameters, Ra, Pr and Sc. It is shown that the stronger the convection relative to the diffusion in solution is, the more backward the upperparts of the stable crystal growth face and dissolution face are inclined. The orientation and the shape of dissolution face hardly affect the stable shape of crystal growth face and vice versa.

Stability of liquid crystal systems doped withγ-Fe_(2)O_(3)nanoparticles

In order to explore the stability of a liquid crystal(LC)system doped withγ-Fe_(2)O_(3)nanoparticles,the physical properties(clearing point,dielectric properties),electro-optical properties and residual direct-current voltage(RDCV)of the doped LC system were measured and evaluated at different times.First,the temperature was controlled by precision hot stage,and the clearing point temperature of doped LC was observed and measured by a polarized optical microscope.Using a precision LCR meter,we measured the capacitance-voltage curves of the doped LC system at the temperature of 27℃.The dielectric constant of doped LC was calculated by the dualcell capacitance method.Then,the electro-optical properties of the doped LC system were measured.Finally,the RDCV of the doped LC system was measured and calculated.After five months,the parameters of the doped LC system were re-measured and analyzed under the same conditions to evaluate its stability.The experimental results show that,within five months,the clearing point change rate of doped LC is in the range of 0.24%-1.37%,the change of dielectric anisotropy is in the range of 0.035-0.2,the curves of electro-optical properties are basically fitted,and the change rate of saturated RDCV is about 11.2%,which basically indicate that the LC system doped withγ-Fe_(2)O_(3)nanoparticles has good stability.

Investigation the improvement of high voltage spinel LiNi_(0.5)Mn_(1.5)O_(4) cathode material by anneal process for lithium ion batteries

The spinel LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)has been attracted great attention as lithium ion cathode material due to its high voltage and large energy density.However,the practical application of LNMO is still limited by poor cycling stability.Herein,to improve the cycling stability of spinel LNMO,it was treated with anneal process at 900℃for 2 h after prepared by traditional solid-state method(LNMO-A).LNMO-A sample presented better electrochemical property especially under high rate,with capacity of 91.2 mAhg^(-1) after 1000 cycles under 10 C.Its superior electrochemical property was ascribed to the anneal process,resulting a stable crystal structure,indicated by XRD and Raman results of electrodes after 1000 cycles under 10 C and the longer solid-solution reaction,revealed by in-situ XRD.In addition,the optimized particle size,micro morphology and the larger BET area surface induced by the recrystallization in anneal process also contributes to its superior electrochemical property.What's more,the thin layer,which interacted LNMO-A particles with each other,induced by particles remelting in anneal process is also beneficial for its excellent electrochemical property.This study not only improved the electrochemical properties by anneal process,but also revealed the origins and mechanisms for its improvement.

Influence of interlayer water molecules in Ni-based catalysts for oxygen evolution reaction

Nickel-iron layered double hydroxides(NiFe LDHs) have been identified as one of the best promising electrocatalysts-candidates for oxygen evolution reaction(OER). However, the catalytic activity effected by interlayer water molecules is ignored and rarely reported. Herein, Ni(OH)_2, NiFe LDHs vertically aligned Ni foam are designed for OER. As a contrast, the corresponding electrocatalysts with the removal of the interlayer water molecules(Ni(OH)_2-AT, NiFe LDHs-AT) are developed to probe into the influence of the interlayer water molecules towards OER. As expected, NiFe LDH nanoplates exhibit excellent catalytic performance and durability for water electrolysis in alkaline conditions with lower overpotential and smaller Tafel slope compared to those of NiFe LDHs-AT, which are influenced mainly by stability of crystal structure due to the existence of interlayer water molecules. The discovery opens up a similar pathway by controlling the amount of water molecules to boost catalytic performance for studying other electrocatalysts with heteroatom dopant.

A selective reflecting film with a temperature-dependent pitch length

A(polymer network/liquid crystal/chiral dopants) composite exhibiting a temperature-sensing switch of infrared spectrum has been developed.Because of the different change of the chiral dopant in the helical twisting power and the anchoring effect of the polymer network,the polymer stabilized liquid crystal(PSLC) films,of which the bandwidth of the selective reflection spectra increased with changing temperature,were obtained.

Continuous generation of lattice oxygen via redox engineering for boosting toluene degradation performances

Excellent performances promoted by lattice oxygen have attracted wide attention for catalytic degradation of volatile organic compounds(VOCs).However,how to control the continuous regeneration of lattice oxygen from the support is seldom reported.In this study,we selected sepiolite supported manganese-cobalt oxides(Co_(x)Mn_(100-x)O_(y))as model catalysts by tuning Co/(Co+Mn)mass ratio(x=3%,10%,15%,and 20%)to enhance toluene degradation efficiency,owing to lattice oxygen regeneration by redox cycle existing at the interface and Mn species with high valence state,initiated by cobalt catalytic performance under the role of crystal field stability phase.The results of activity test show that the sepiolite-Co_(15)Mn_(85)O_(y)catalyst exhibit outperformances at 193℃with 10,000 h^(-1)GHSV.In addition,the catalyst existed at the bottom of the"volcano"curve correlated T_(50)or T_(90)with Co/(Co+Mn)weight ratio is sepiolite-Co_(15)Mn_(85)O_(y),conforming its outperformance.Further characterized by investigating active sites structural and electronic properties,the essential of superior catalytic activity is attributed to the grands of lattice oxygen continuous formation resulted from redox engineering based on the high atomic ratio of surface lattice oxygen with continuous refilled from the support and that of Mn^(4+)/Mn^(3+)cycle initiated by cobalt catalytic behaviors.All in all,redox engineering,not only promotes grands of active species reversible regeneration,but supplies an alternative catalyst design strategy towards the terrific efficiency-to-cost ratio performance.

Cauchy-Born Rule and the Stability of Crystalline Solids:Dynamic Problems

We study continuum and atomistic models for the elastodynamics of crystalline solids at zero temperature. We establish sharp criterion for the regime of validity of the nonlinear elastic wave equations derived from the well-known Cauchy-Born rule.

Synthesis, crystal structure and thermal analysis of tetraiodo-4,4'-bi-1,2,4-triazole

Tetraiodo-4,4＇-bi-l,2,4-triazole （1） was synthesized from a reaction of iodine monochloride witb 4,4＇ bi- 1,2,4-triazole （2）, which was prepared by a transamination reaction between 4-amine-1,2,4-triazole and N,N-dimethylformamide azine dihydrochloride （3） obtained via a Vilsmeier reaction. The title compound was extensively characterized by melting point, elemental analysis, 1R, HRMS and single crystal X-ray diffraction. The single crystal X-ray structural analysis reveals that compound 1 exhibits a stable conformation with the two triazole rings being perpendicular to minimize three-dimensional steric hindrance and stacking through aromatic zr. analysis from TGA and DSC indicates that resnectivelv. Jr packing interactions between molecules. The therma compound I decomposes at 275.40 ℃ and 338.35 C

Crystallization induced micellization of poly(p-dioxanone)-block-polyethylene glycol diblock copolymer functionalized with pyrene moiety

Poly（p-dioxanone）-block-polyethylene glycol diblock copolymers functionalized with pyrene moieties（Py-PPDO-b-PEG） at the chain ends of PPDO blocks were synthesized for preparing anisotropic micelles with improved stability.The micellization and crystallization of the copolymers were investigated by nano differential scanning calorimetry（Nano DSC）,transmission electron microscopy（TEM）,UV-vis spectrophotometery,fluorophotometer,and dynamic light scattering（DLS）,respectively.The results indicated that the aggregation of pyrene induced by intermolecular interaction lead to micellization of Py-PPDO-b-PEG at much lower concentrations than those of PPDO-b-PEG copolymers without pyrene moieties.The aggregation of pyrene moieties may also serve as nucleation agent and therefore enhance the crystallization rate of PPDO blocks.Fluorescence measurements by using Nile Red as the fluorescent agent indicated that the micelles of Py-PPDO-b-PEG have high stability and load capacity for hydrophobic molecules.

Charge distribution into illuminated dye-doped surface stabilized ferroelectric liquid crystal cell

Surface stabilized （anti） ferroelectric liquid crystal cells can be used as an optically addressed media for optical data processing. The structure of the cell has to contain a photo sensible agent, i.e, an absorbing dye-doped orienting layer. The all-optical generation of the diffractive grating can be done due to the switching parameters of the smectic slab within cells with a sensitive layer. This Letter considers a study of the optically induced charge generation into the dye-doped layer, and the explanation of the phenomena of the selective molecular director reorientation, while cell driving what leads to the induction of phase grating.

Structure, magnetic properties, and thermal stability of Sm(1-x)Tm_xCo_5compounds

Structure, magnetic properties, and thermal stability of ternary Sm1-xTmxCo5 compounds were studied via X-ray diffraction（XRD）, thermal magnetic analysis（TMA）, and magnetic measurements. XRD results show that all the compounds have a main phase of hexagonal CaCu5-type crystal structure with small amount of impurity phases; increasing Tm content is associated with contraction of the hexagonal unit cell in the direction of the c axis and expansion of the a and b parameters. TMA results indicate that the Curie temperature（TC） of Sm1-xTmxCo5 compounds gets higher with the increase in Tm content.Magnetic measurements show that both the magnetic anisotropy field（HA） and the magnetization at an applied field of 7 T（M7 T） decrease with the increase of Tm content. However, the thermal stability of both the HAand M7 Tof all the Tm doped compounds is remarkably improved compared with that of the pure SmCo5 compound, leading to the result that both the M7 Tand HAof Sm0.8Tm0.2Co5 .2are higher than those of SmCo5 compound at 473 K, which indicates the good potential of Tm doped compound in the practical applications at elevated temperature.

Yb^(3+)-doped Fluorophosphate Glass with High Cross Section and Lifetime

Yb3＋ doped fluorophosphate （FP/Yb） glasses with emission cross section and fluorescence lifetime as high as 0.8388×10-20 cm 2 and 2.3 ms were developed,and AlF3 content is proved to decrease the lifetime obviously.Large scale glass casting procedure shows high Tx-Tg doesn t make better casting crystallization stability in certainty.Although Yb laser is difficult to be obtained in FP glass,a 230 mw laser was still achieved from 2 mm thick samples under 976 nm LD excitation because of the large gain parameter（σemiτf） of the FP/Yb glass.Lasing test also proved the relationship between laser output and gain parameter.Combined with its wide and flat effective gain property,this FP/Yb glass is a practical new potential material for low power ultra-short pulse application.