Synthesis and electrochemical properties of Al-doped LiVPO_4F cathode materials for lithium-ion batteries

Al-doped LiVPO4F cathode materials LiAlxV1-xPO4F were prepared by two-step reactions based on a car-bothermal reduction （CTR） process. The properties of the Al-doped LiVPO4F were investigated by X-ray diffraction （XRD）,scanning electron microscopy （SEM）,and electrochemical measurements. XRD studies show that the Al-doped LiVPO4F has the same triclinic structure （space group p-↑1 ） as the undoped LiVPO4F. The SEM images exhibit that the particle size of Al-doped LiVPO4F is smaller than that of the undoped LiVPO4F and that the smallest particle size is only about 1 μm. The Al-doped LiVPO4F was evaluated as a cathode material for secondary lithium batteries,and exhibited an improved reversibility and cycleability,which may be attributed to the addition of Al^3＋ ion by stabilizing the triclinic structure.

Synthesis and characterization of triclinic structural LiVPO_4F as possible 4.2 V cathode materials for lithium ion batteries

A potential 4.2 V cathode material LiVPO4F for lithium batteries was prepared by two-step reaction method based on a carbon-thermal reduction （CTR） process. Firstly, V2O5, NH4H2PO4 and acetylene black are reacted under an Ar atmosphere to yield VPO4. The transition-metal reduction is facilitated by the CTR based on C→CO transition. These CTR conditions favor stabilization of the vanadium as V^3＋ as well as leaving residual carbon, which is useful in the subsequent electrode processing. Secondly, VPO4 reacts with ElF to yield LiVPO4F product. The property of the LiVPO4F was investigated by X-ray diffractometry （XRD）, scanning electron microscopy （SEM） and electrochemical measurement. XRD studies show that LiVPO4F synthesized has triclinic structure（space group p I ）, isostructural with the naturally occurring mineral tavorite, EiFePO4-OH. SEM image exhibits that the particle size is about 2μm together with homogenous distribution. Electrochemical test shows that the initial discharge capacity of LiVPO4F powder is 119 mA·h/g at the rate of 0.2C with an average discharge voltage of 4.2V （vs Ei/Li^＋）, and the capacity retains 89 mA·h/g after 30 cycles.

Single-atom catalysts for the electrochemical reduction of carbon dioxide into hydrocarbons and oxygenates

The electrochemical reduction of carbon dioxide offers a sound and economically viable technology for the electrification and decarbonization of the chemical and fuel industries.In this technology,an electrocatalytic material and renewable energy-generated electricity drive the conversion of carbon dioxide into high-value chemicals and carbon-neutral fuels.Over the past few years,single-atom catalysts have been intensively studied as they could provide near-unity atom utilization and unique catalytic performance.Single-atom catalysts have become one of the state-of-the-art catalyst materials for the electrochemical reduction of carbon dioxide into carbon monoxide.However,it remains a challenge for single-atom catalysts to facilitate the efficient conversion of carbon dioxide into products beyond carbon monoxide.In this review,we summarize and present important findings and critical insights from studies on the electrochemical carbon dioxide reduction reaction into hydrocarbons and oxygenates using single-atom catalysts.It is hoped that this review gives a thorough recapitulation and analysis of the science behind the catalysis of carbon dioxide into more reduced products through singleatom catalysts so that it can be a guide for future research and development on catalysts with industry-ready performance for the electrochemical reduction of carbon dioxide into high-value chemicals and carbon-neutral fuels.

Luminescence of Eu ^(3+) in LnAlO_3 (Ln=Gd,Y) under UV and VUV Excitation

Single phases of LnAlO 3:Eu 3+ (Ln=Gd,Y) were obtained by the process of evaporation of their nitric acid solution, and then pyrolysis of their nitrate salts. On monitoring by 613 nm emission, broad bands at around 270 and 170 nm were observed in the excitation spectrum of Gd 0.95Eu 0.05AlO 3. These peaks could be assigned to charge transfer (CT) transitions of Eu 3+-O 2- and Gd 3+-O 2- respectively. All the transitions observed in Gd 0.95Eu 0.05AlO 3 are faithfully reproduced in the Y 0.95Eu 0.05AlO 3, but with an exception of the 8S 7/2→ 6I 11/2 transition of Gd 3+. The 153 nm broad band could be the CT transition of Y 3+-O 2-. Accordingly, the efficiency luminescence of (Gd,Y)BO 3:Eu 3+ was explained as a result of CT transitions of Gd 3+-O 2- and Y 3+-O 2- under 147 nm excitation. Under VUV excitation, Gd 0.95Eu 0.05AlO 3 exhibits a bright red luminescence with CIE chromaticity coordinates of (0.623, 0.335) with a PL intensity of 30 of the commercial phosphor (Gd,Y)BO 3:Eu 3+ (KX-504A). The PL spectrum of Y 0.95Eu 0.05AlO 3 is similar to that of Gd 0.95Eu 0.05AlO 3. Calculation of the color coordinates gives x=0.636, y=0.340 with a PL intensity of 50 of the (Gd,Y)BO 3:Eu 3+ (KX-504A) for Y 0.95Eu 0.05AlO 3, and confirms that it has the appearance of pure spectral red, corresponding approximately to 608 nm. It can be concluded that LnAlO 3:Eu 3+ is a promising red VUV phosphor.

Effects of synthesis conditions on the structural and electrochemical properties of layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_2 cathode material via oxalate co-precipitation method

The uniform layered LiNi1/3Co1/3Mn1/3O2 cathode material for lithium ion batteries was prepared by using （Ni1/3Co1/3Mn1/3）C2O4 as precursor synthesized via oxalate co-precipitation method in air. The effects of calcination temperature and time on the structure and electrochemical properties of the LiNi1/3Co1/3Mn1/3O2 were systemically studied. XRD results revealed that the optimal calcination conditions to prepare the layered LiNi1/3Co1/3Mn1/302 were 950℃ for 15 h. Electrochemical measurement showed that the sample prepared under the such conditions has the highest initial discharge capacity of 160.8 mAh/g and the smallest irreversible capacity loss of 13.5% as well as stable cycling performance at a constant current density of 30 mA/g between 2.5 and 4.3 V versus Li at room temperature.

Verification of Beam Models for Ionic Polymer-Metal Composite Actuator

Ionic Polymer-Metal Composite (IPMC) can work as an actuator by applying a few voltages.A thick IPMC actuator,where Nafion-117 membrane was synthesized with polypyrrole/alumina composite filler,was analyzed to verify the equivalent beam and equivalent bimorph beam models.The blocking force and tip displacement of the IPMC actuator were measured with a DC power supply and Young's modulus of the IPMC strip was measured by bending and tensile tests respectively.The calculated maximum tip displacement and the Young's modulus by the equivalent beam model were almost identical to the corresponding measured data.Finite element analysis with thermal analogy technique was utilized in the equivalent bimorph beam model to numerically reproduce the force-displacement relationship of the IPMC actuator.The results by the equivalent bimorph beam model agreed well with the force-displacement relationship acquired by the measured data.It is confirmed that the equivalent beam and equivalent bimorph beam models are practically and effectively suitable for predicting the tip displacement,blocking force and Young's modulus of IPMC actuators with different thickness and different composite of ionic polymer membrane.

Preparation and characterization of carbonyl iron soft magnetic composites with magnesioferrite insulating coating layer

Spherical carbonyl iron(Fe)powders were coated with magnesioferrite(MgFe2O4)insulating coating layer and then mixed with epoxy-modified silicone resin(ESR).Soft magnetic composites(SMCs)were fabricated by compaction of the coated powders and annealing treatment.Transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffractometry(XRD)and X-ray photoelectron spectroscopy(XPS)revealed that the MgFe2O4 layer was coated on the surface of the iron powders.The magnetic properties of SMCs were determined using a vibrating sample magnetometer and an auto testing system for magnetic materials.The results showed that the SMCs prepared at 800 MPa and 550℃ exhibited a significant core loss of 167.5 W/kg at 100 kHz and 50 mT.

Synthesis, Characterization and Fluorescence of Terbium(Ⅲ) Complexes with Phenylglyoxylic Acid and 2,2-Dipyridine, 1,10-Phenanthroline, Triphenyl Phosphine Oxide

Three new complexes TbL3dipy （H2O）2, TbL3phen （H2O） 2 and TbL2 （TPPO） 2NO3 were synthesized （L = phenylglyoxylate ion, dipy = 2, 2-dipyridine, phen = 1,10-phenanthmline, TPPO = Triphenyl phosphine oxide）. Elemental analysis, conductivity, IR spectra, and ^1HNMR spectra studies were performed. IR spectra indicate that the carboxylate ion of phenylglyoxylate is coordinated to the Tb（Ⅲ） ion as an unidentate ligand. In ^1HNMR, the signals of different hydrogens in phenylglyoxylate ion shift upfield. The excitation and emission spectra of the three solid complexes were recorded at morn temperature, in which the optimum excitation wavelengths are, 361.0, 359.0 and 367.0 nm for these three complexes, respectively. Four emission bands due to the ^5D4-^7Fj（j = 6, 5, 4, 3） transitions were observed for TbL3dipy（H2O）2（489.0, 545.0, 584.0, 620.0 nm） and TbL3phen（H2O）2（490.0, 544.0, 583.0, 620.0 nm）. Under the same conditions, only one emission band due to the ^5D4-^7F5 transition was observed for the complex TbL2（TPPO）2NO3. The emission intensity of TbL3dipy（H2O）2 is the strongest among the three complexes.

Structure and Luminescence Property of a Hexanuclear Silver(I) Cluster Containing Pyridine-3-carboxaldehyde Thiosemicarbazone

A new hexanuclear silver（I） compound containing thiosemicarbazone with group of 3-pyridine was synthesized and structurally characterized by single-crystal X-ray diffraction,elemental analysis and fluorescence spectrum.The title compound 3 crystallizes in monoclinic,space group C2/m with a = 18.6523（9）,b = 24.7519（11）,c = 22.4542（15） ,β = 93.4960（10）°,V = 10347.4（10）3,C68H104Ag6N30O8S6,Mr = 2309.39,Dc = 1.482g/cm3,μ（MoKα） = 1.293 mm-1,F（000） = 4656,Z = 4,the final R = 0.0544 and wR = 0.1580 for 6733 observed reflections（I 〉 2σ（I））.In the structure,two Ag6L36（L3 = pyridine-3-carboxaldehyde thiosemicarbazone） clusters are contained.In each cluster,the S atom of ligand L3 served as a triply bridged chelator to connect the six silver atoms into a Ag6L36 cluster.Luminescence investigation revealed that the band at 630 nm was attributed to cluster-centered（CC） electron transfer,and those at 493 and 530 nm to the LMCT and CC transitions,respectively.

Structure and Luminescence Property of a Hexanuclear Silver(Ⅰ) Cluster Containing Benzaldehyde Thiosemicarbazone

A new hexanuclear silver （I） compound 2 containing thiosemicarbazone with the group of benzene was synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analysis and fluorescence spectrum. The title compound crystallizes in triclinic, space group P with a = 11.611（3）, b = 15.610（5）, c = 15.624（7） , α = 113.942（6）, β = 104.520（6）, γ = 104.230（4）°, V = 2304.1（14） 3, C60H77Ag6N22O4.5S6, Mr = 2018.02, Dc = 1.454 g/cm3, μ（MoKα） = 1.435 mm-1, F（000） = 1005, Z = 1, the final R = 0.0468 and wR = 0.1474 for 6608 observed reflections （I 2σ（I））. In the structure, the S atom of the ligand L2 （L2 = benzaldehyde thiosemicarbazone） served as a triply bridged chelator to connect the six silver atoms into a Ag6L26 cluster. The luminescence property of compound 2 was investigated at room temperature.

Microwave synthesis and characterization of new red long afterglow phosphor Sr_3Al_2O_6:Eu

Nanoparticles of red long afterglow phosphor Sr3Al2O6: Eu2+ were prepared by microwave irradiation method at a power of 680 W and a processing time of 15 min. The phosphors nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fluorescence spectrophotometer techniques. The results reveal that the samples are composed of single Sr3Al2O6 phase. The resultant nanoparticles show small size (80?100 nm) and spherical shape. The excitation and emission spectra indicate that excitation broad band chiefly lies in visible range and the nanoparticles emit much strong light at 612 nm under around 473 nm excitation. And the long afterglow phosphorescence of Sr3Al2O6 doped with Eu2+ was observed in the dark with naked eye after the removal of the excitation light. The effect of Eu2+ doping concentrations of the samples on the emission intensity is studied systematically. Furthermore, the microwave method requires a very short heating-time and the energy consumption.

Design of pyrite/carbon nanospheres as high-capacity cathode for lithium-ion batteries

Transition metal sulfides are emerging as promising electrode materials for energy storage and conversion.In this work,hierarchical FeS2/C nanospheres are synthesized through a controllable solvothermal method followed by the annealing process.Spherical FeS2 core is homogeneously coated by thin carbon shell.The hierarchical nanostructure and carbon coating can enhance electron transfer and accommodate the stress originated from the volume change as well as suppress the shuttle effect of polysulfide.Consequently,as the cathode material of lithium ion batteries(LIBs),the FeS2/C nanospheres exhibit high reversible capacity of 676 m Ahg^-1 and excellent cycling life with the capacity retention of 97.1%after100 cycles.In addition,even at the high current density of 1.8 C,a reversible capacity of 437 m Ahg^-1 is obtained for the FeS2/C nanospheres,demonstrating its great prospect for practical applications in highperformance LIBs.

Structure and Luminescence Property of a Hexanuclear Thiosemicarbazone Silver(I) Cluster

A new hexanuclear silver（I） compound containing thiosemicarbazones with groups of 1-naphthalene was synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analysis and fluorescence spectrum. The title compound crystallizes in monoclinic, space group P21/c with a = 16.101（4）, b = 24.855（7）, c = 14.492（4） A, β = 109.730（5）, V = 5459（3） A3, C90H102Ag6N2406S6, Mr= 2455.54, Dc= 1.494 g/cm3,μ（MoKa） = 1.228 mm^-1, F（000） = 2472, Z = 2, the final R = 0.0761 and wR = 0.1507 for 5258 observed reflections （I〉 2α（I））. In the structure, the S atom of ligand L serves as a triply bridged chelator to connect the six silver atoms into a Ag6L6 cluster. Luminescence investigation reveals that the compound exhibits two ligand-independent cluster-centered electron transfer bands and one ligand-dependent charge transfer band.

Atomic Layer Deposition-Assisted Construction of Binder-Free Ni@N-Doped Carbon Nanospheres Films as Advanced Host for Sulfur Cathode

Rational design of hybrid carbon host with high electrical conductivity and strong adsorption toward soluble lithium polysulfides is the main challenge for achieving high-performance lithium-sulfur batteries(LSBs).Herein,novel binder-free Ni@N-doped carbon nanospheres(N-CNSs)films as sulfur host are firstly synthesized via a facile combined hydrothermal-atomic layer deposition method.The cross-linked multilayer N-CNSs films can effectively enhance the electrical conductivity of electrode and provide physical blocking“dams”toward the soluble long-chain polysulfides.Moreover,the doped N heteroatoms and superficial NiO layer on Ni layer can work synergistically to suppress the shuttle of lithium polysulfides by effective chemical interaction/adsorption.In virtue of the unique composite architecture and reinforced dual physical and chemical adsorption to the soluble polysulfides,the obtained Ni@N-CNSs/S electrode is demonstrated with enhanced rate performance(816 mAh g?1 at 2 C)and excellent long cycling life(87%after 200 cycles at 0.1 C),much better than N-CNSs/S electrode and other carbon/S counterparts.Our proposed design strategy offers a promising prospect for construction of advanced sulfur cathodes for applications in LSBs and other energy storage systems.

Luminescent Properties of A Novel Terbium Complex Tb(o-BBA)_3(phen)

A novel rare earth complex of terbium ion with 2-benzoylbenzoic acid and 1, 10-phenathroline （Tb（o-BBA）3 （phen）, o-BBA-2-benzoylbenzoic acid, phen = 1, 10-phenathroline） was used as an electroluminescent material for the first time. The Tb complex was blended with poly（N-vinylcarbazole） （PVK） in different weight ratios and spinn to coated into films （noted as PVK ：Tb films）. The photoluminescence （PL） properties of films were investigated and the optimum weight ratio between PVK and Tb（o-BBA）3（phen） was found to be 3：1. Monolayer devices with the structure ITO/PVK： Tb/AI were fabricated and emitted green light, which was characteristic of Tb^3＋ emission. The results show that mecha- nisms for PL and EL are different. The PL is considered to be caused because of energy transfer and direct excitation to the Tb（o-BBA）3（phen） molecule, while EL is mainly on charging trapping.

Microstructure and Properties of Mg-8Li-3Al-1Y Alloy

Microstructure of as-cast and extruded Mg-8Li-1Al-1Y alloy specimens was analyzed with OM,SEM and XRD.Results show that as-cast specimens are composed of α phase(Mg),β phase(Li) and rod-like Al2Y compound.In the extruded specimens,the microstructure is refined and the β phase has the effect of coordination during deformation.After extruding process,the Al2Y compound distributes evenly in the extruding direction.The results of mechanical properties tests show that the strength and elongation are both improved after extruding deformation.

Synthesis, Crystal Structure and Theoretical Calculation of [2-(2,6-Dioxacyclohexyl)-5-methoxylphenols]_2

The title compound [2-（2,6-dioxacyclohexyl）-5-methoxylphenols]2 was synthesized by the reaction of 2-hydroxyl-3-methoxylbenzaldehyde and 1,3-propanediol in the presence of DMF-DMS adduct and characterized by IR spectrum, UV-Vis spectrum and X-ray crystallography. The title compound belongs to monoclinic, space group P21 with a = 9.8967（10）, b = 8.2240（9）, c = 13.3654（14） A^°, β= 90.016（2）°, C11H14O4, Mr = 210.22, V = 1087.8（2）A^°3, Z = 4, Dc = 1.284 Mg/m^3, F（000） = 448,μ = 0.098 mm^-1, the final R = 0.0300 and wR = 0.0761 for 2070 observed reflections with I 〉 2σ（I）. The molecules are connected via intermolecular O-H…O hydrogen bonds into a 2D network structure. Moreover, theoretical investigations of the title compound with HF/6-31G（d） method were performed, and its stability, frontier molecular orbital composition and Mulliken charge distribution were also discussed. The compound is a bis-molecule. The two molecules stay together and could not be separated. Two crystallographically independent molecules exist in an asymmetric unit. The bond lengths and bond angles of the two molecules are slightly different with each other.

Investigation of Heterogeneous Ice Nucleation on the Micro-Cubic Structure Superhydrophobic Surface for Enhancing Icing-Delay Performance

The aim of this study is to explore the heterogeneous ice nucleation behavior based on controllable micro-cubic array structure surfaces from the statistic perspective.To this end,we firstly constructed a group of micro-cubic array structures on silicon substrates by a selective plasma etching technique.After grafting low-free-energy substance,the as-constructed micro-cubic array structure surfaces exhibited higher non-wettability with the water contact angle being up to 150°.On this basis,500 cycles of freezing and melting processes were accurately recorded to analyze the instantaneous ice nucleation behavior according to the statistical results of freezing temperature.As a consequence,the statistical freezing temperature of the sample with micro-spacing distance of 40μm is as low as−17.13°C.This microstructure configuration(conforming to Cassie-Baxter wetting regime)not only could entrap more air pockets,but also achieved lower solid-liquid contact area,resulting in lower ice nucleation rate(~2–3 orders of magnitude less than that on the flat substrate).Furthermore,the gradually increasing micro-spacing distance to 60μm would induce the transition from CassieBaxter to Wenzel wetting state,leading to higher freezing probability and ice nucleation rate.The complete understanding on microstructure configuration improving the ice nucleation will lay the foundation stone for the microstructure design of ice-repellent materials.

Hot deformation behavior and processing map of squeeze cast ZK60 magnesium alloy

The deformation behavior of squeeze cast ZK60 magnesium alloy was investigated by compressive tests conducted at temperatures of 250-450℃and strain rates of 0.001-10 s-1 with Gleeble—1500D thermal simulator system. The hot deformation behavior of squeeze cast ZK60 magnesium alloy was characterized using processing map developed on the basis of the dynamic materials model. The processing map gives safe 'processing windows' in which the processes of dynamic recovery and dynamic recrystallization occur. It reveals that the dynamic recrystallization domain occurs at 375℃and strain rate of 0.001 s-1,and its power dissipation efficiency approximately corresponds to 36%, which should be considered the optimum parameters for hot working of squeeze cast ZK60 magnesium alloy. The variation of the instability parameterξ(ε) with temperature and strain rate constitutes an instability map, which is used for delineating the region of flow instability. The material exhibits flow instability which should be avoided in mechanical processing.

Crystal Structure of a Hexanuclear Silver（Ⅰ） Compound [Ag_6L^66]·4DMF and Luminescence Discussion of a Series of Silver（Ⅰ） Clusters

A new silver（Ⅰ） compound 6 （[Ag6L66]·4DMF） containing thiosemicarbazone with the group of 2-chloro-1-benzene was synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analysis and fluorescence spectrum. The title compound 6 crystallizes in monoclinic, space group C2/c with a = 26.9236（18）, b = 15.2553（8）, c = 24.6237（13） , β = 103.0680（10）°, V = 9851.7（10）3, C58H66Ag6Cl6N20O3S6, Mr = 2143.59, Dc = 1.445 g/cm3, μ（MoKα） = 1.503 mm-1, F（000） = 4232, Z = 4, the final R = 0.0565 and wR = 0.1654 for 5831 observed reflections （Ⅰ 〉 2σ（Ⅰ））. Similar to the structure of the compounds we have reported, compound 6 also exhibits a hexanuclear silver（Ⅰ） cluster. In the cluster, the S atom of ligand L6 （L6 = 2-chloro-1-benzaldehyde thiosemicarbazone） served as a triply bridged chelator to connect the six silver atoms into a Ag6L66 cluster. The luminescence property of compound 6 was investigated at room temperature and compared with other similar compounds in order to find the factors influencing their luminescent property.