Polyoxovanadate ionic crystals with open tunnels stabilized by macrocations for lithium-ion storage

Polyoxometalates(POMs)with multiple redox active sites have been reported as charge sponge for lithium-ion batteries(LIBs).Herein,we for the first time introduce a polyoxovanadate(POV)ionic crystals with macrocations,[Ni(Phen)_(3)][ClV_(14)O_(34)]Cl(NiV_(14),Phen=1,10-phenanthroline),as an anode material for LIBs.The existence of macrocation[Ni(Phen)_(3)]^(2+)stabilizes the open tunnels inside NiV_(14).The NiV_(14)electrode exhibits superior rate capabilities(1083 mAh·g^(-1)at 100 mA·g^(-1)and 384 mAh·g^(-1)at 2000 mA·g^(-1))due to the rapid capacitive dominated contribution and high Li^(+)ions diffusion coefficients(3.3×10^(-12) cm^(-2)·s^(-1)),and it delivers a remarkable cycling stability with a Coulombic efficiency of 99.7%after 1000 cycles at 2000 mA·g^(-1).Such performance can be attributed to the stable structure of NiV14 and the highly reversible valence changes of vanadium during the charge/discharge processes,which are revealed by a combination of in situ X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and X-ray absorption fine structure(XAFS)measurements.This work not only demonstrates that NiV_(14) with open tunnels stabilized by macrocation is a promising anode material for high performance LIBs,but also provides important references for the rational design of POMs electrode materials in advanced energy storage systems.

Ultrasonic generation via direct interaction between photons and phonons in anharmonic lattice of ionic crystals

A theory of ultrasonic generation via direct interaction of transverse optic (TO) phonons with photons in anharmonic lattice of ionic crystals is presented. There are two methods of supplying light energy for the excitation of TO lattice wave as a high frequency ultrasound: (A) incident light comes from the source outside the cavity? fulfilled with ionic crystal medium, (B) photon mode of the cavity possesses the gain of amplification by stimulated radiation of active atoms doping in the medium. More attention is drawn to the case (B). The working system of case (B), as a mixture of lasing action and ultrasonic generation, has the threshold phenomena like usual laser. And the linear stability analysis shows that the nonlineax phonon-photon coupling and the interaction among phonons themselves, both of which reflect the anharmonicity of lattice vibration, are necessary to the stable ultrasonic output. So this laser-ultrasonic generation mixture would be also a measure to investigate the lattice-dynamic nonlinearity and correlated electromagnetic properties of ionic crystals.

The Even-Odd and the Isoelectronicity Rules Applied to Single Covalent Bonds in Ionic, Double-Face-Centered Cubic and Diamond-Like Crystals

Although atom configuration in crystals is precisely known thanks to imaging techniques, there is no experimental way to know the exact location of bonds or charges. Many different representations have been proposed, yet no theory to unify conceptions. The present paper describes methods to derive bonds and charge location in double-face-centered cubic crystals with 4 and 6 atoms per unit cell using two novel rules introduced in earlier works: the even-odd and the isoelectronicity rules. Both of these rules were previously applied to ions, molecules and some solids, and the even-odd rule was also tested on two covalent crystal structures: centered-cubic and single-face-centered cubic crystals. In the present study, the diamond-like structure was subjected to the isoelectronicity rule in order to derive Zinc-blende structures. Rock-salt-like crystals were derived from each other using both rules. These structures represent together more than 230 different crystals. Findings for these structures are threefold: both rules describe a very sure method to obtain valid single covalent-bonded structures;single covalent structures can be used in every case instead of the classical ionic model;covalent bonds and charges positions do not have any relation with the valence number given in the periodic table.

Structure and ion transport properties of organic ionic compounds revealed by NMR

Organic ionic plastic crystals(OIPCs)are emerging as an important material family for solid-state electrolytes and many other applications.They have significant advantages over conventional electrolyte materials,such as high ionic conductivity,non-flammability,and plasticity.Various nuclear magnetic resonance(NMR)spectroscopy techniques including solid-state NMR,pulsed-field gradient(PFG)NMR,and magnetic resonance imaging(MRI)etc.,provide us a versatile toolkit to understand the fundamental level structures,molecular dynamics,and ionic interactions in these materials.This article reviews the commonly used NMR methods including solid-and solution-state NMR,PFG-NMR,dynamic nuclear polarization(DNP)and the application of these methods in revealing the microscopic level structures and ion-transport mechanisms in OIPC materials.

Poly(carbonate)-based ionic plastic crystal fast ion-conductor for solid-state rechargeable lithium batteries

Liquid plasticizers with a relatively higher dielectric coefficient like ethylene carbonate(EC),propylene carbonate(PC),and ethyl methyl carbonate(EMC) are the most commonly used electrolyte materials in commercial rechargeable lithium batteries(LIBs) due to their outstanding dissociation ability to lithium salts.However,volatility and fluidity result in their inevitable demerits like leakage and potential safety problem of the final LIBs.Here we for the first time device a subtle method to prepare a novel thermal-stable and non-fluid poly(carbonate) solid-state electrolyte to merge EC with lithium carriers.To this aim,a series of carbonate substituted imidazole ionic plastic crystals(G-NTOC) with different polymerization degrees have been synthesized.The resulting G-NTOC shows an excellent solid-state temperature window(R.T.-115℃).More importantly,the maximum ionic conductivity and lithium transference number of the prepared G-NTOC reach 0.36 × 10^(-3) S cm^(-1) and 0.523 at 30℃,respectively.Galvanostatic cycling test results reveal that the developed G-NTOC solid-state electrolytes are favorable to restraining the growth of lithium dendrite due to the excellent compatibility between the electrode and the produced plastic crystal electrolyte.The fabricated LiIG-NTOCILiFeP04 all-solid-state cell initially delivers a maximum discharge capacity of 152.1 mAh g^(-1) at the discharge rate of 0.1 C.After chargingdischarging the cell for 60 times,Coulombic efficiency of the solid-state cell still exceeds 97%.Notably,the LiIG-NTOCILiFeP04 cell can stably light a commercial LED with a rated power of 0.06 W for more than1 h at 30℃,and the output power nearly maintains unchanged with the charging-discharging cycling test,implying a sizeable potential application in the next generation of solid-state LIBs.

Synthesis and Structure of a POMs-based 3D Zeolike Ionic Crystal,{[Co(dpdo)_2(H_2O)_2(CH_3CN)]_2(SiMo_(12)O_(40))(H_2O)_2}_n

A POMs-based 3D zeolike ionic crystal 1, {[Co（dpdo）2（CH3CN）（H2O）2]2（SiMo12O40）- （HEO）2}n （dpdo = 4,4＇-bipyridine-N,N＇-dioxide）, was constructed via self-assembly by embedding Keggintype [SiMo12O40]^4- polyanions within the intercrystalline voids as pillars and structurally characterized. The crystal structure was determined by single-crystal X-ray diffraction. The crystal is of triclinic, space group P1 with a = 11.430（3）, b = 12.242（3）, c = 14.279（3）A, α = 106.196（4）,β = 94.316（4）, γ = 98.294（3）°, V = 1884.5（7）A^3 Z = 1, C44H50N10O54CoEMo12Si, Mr = 2880.17, Dc = 2.538 g/cm^3, p = 2.484 mm^-1,F（000） = 1388, the final R = 0.0383 and wR = 0.1096 for 7753 observed reflections with I 〉 2σ（I）. Flack factor is 0.22（3）. Compound 1 is a pillar-layered framework with the [SiMo12O40]^4- anions linearly located on the square voids between the 2D bilayers which are formed by the dpdo ligands and cobalt（II） ions.

Aminopropyl-containing ionic liquid based organosilica as a novel and efficient adsorbent for removal of crystal violet from wastewaters

Herein a novel aminopropyl-containing ionic liquid based organosilica(ILOS-NH_2) is prepared, characterized and applied as effective adsorbent for removal of crystal violet(CV) dye from wastewater. The ILOS-NH2 material was synthesized by hydrolysis and co-condensation of 1,3-bis-(3-trimethoxysilylpropyl)-imidazolium chloride(BTMSPIC) under acidic conditions followed by treatment with 3-aminopropyl-trimethoxysilane in toluene under reflux conditions. This material was characterized using scanning electron microscopy(SEM), diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS), thermal gravimetric analysis(TGA) and energy dispersive X-ray analysis(EDAX). The material was effectively used in the removal of crystal violet at ambient temperature and showed high capacity and stability under applied conditions. The efficacy of p H, contact time, adsorbent dose, initial dye concentration, temperature, and isotherm studies and the applicability of pseudo-first, second order and Elovich kinetic models have also been investigated.

Theoretical prediction of ion conductivity in solid state HfO_2

A theoretical prediction of ion conductivity for solid state HfO2 is carried out in analogy to ZrO2 based on the density functional calculation. Geometric and electronic structures of pure bulks exhibit similarity for the two materials. Negative formation enthalpy and negative vacancy formation energy are found for YSH （yttria-stabilized hafnia） and YSZ （yttria- stabilized zirconia）, suggesting the stability of both materials. Low activation energies （below 0.7 eV） of diffusion are found in both materials, and YSH＇s is a little higher than that of YSZ. In addition, for both HfO2 and ZrO2, the supercells with native oxygen vacancies are also studied. The so-called defect states are observed in the supercells with neutral and ＋1 charge native vacancy but not in the ＋2 charge one. It can give an explanation to the relatively lower activation energies of yttria-doped oxides and ＋2 charge vacancy supercells. A brief discussion is presented to explain the different YSH ion conductivities in the experiment and obtained by us, and we attribute this to the different ion vibrations at different temperatures.

Yuan Jianmin Zhao Yijun Zhang Zhijie (At.Mol.Phys.and Physical Mechanics Research Center,National Univ of Defense Tech.,Changsha,Hunan,P.R.China)

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Crystal structure and thermal decomposition kinetics of1-(pyridinium-1-yl)propane-(1-methylpiperidinium)bi[bis(trifluoromethanesulfonyl)imide], [PyC_3Pi][NTf_2]_2

The structure of a room temperature asymmetrical dicationic ionic liquid （ADIL）, 1-（pyridinium-l-yl） propane- （1-methylpiperidinium） bi[bis（tfifluoromethanesulfonyl）imide] （[PyC3Pi][NTf2]2）, was studied by the X-ray difo fraction method. Meanwhile, thermal analysis of [PyC3Pi][NTf2]2 was also studied using non-isothermal thermo- gravimetric analysis （TGA）. The title crystal belongs to the triclinic with space group Pi and unit-cell parameters a ： 0.95217 （8） nm, b = 1.05129 （11 ） nm, c = 1.70523 （14） nm, ct = 89,759 （8）°,β = 80.657 （7）°, γ=68.007 （9）°, and F（000） = 792. Thermal stability and thermal decomposition kinetics of the title compound were also investigated using TGA under the atmosphere of highly pure nitrogen. Heating curves at different rates were cor- related with kinetic equations Friedman and ASTM （also called iso-conversion method）. The values of average activation E （kJ·mol^-1 ） and pre-exponential constant lgA are 149.58 kJ. mol- 1 and 8.83, respectively, which were obtained by the two methods. The kinetic model function, activation energy and pre-exponential constant of this reaction using the multivariate non-linear-regression method were f（a） = （1 -a）（1 ＋ 4.1870a）, 151.04 kJ·mol^-1 and 8.81, respectively, which were basically consistent with iso-conversion methods.

Ionic liquid crystal-based electrolyte with enhanced charge transport for dye-sensitized solar cells

A room temperature ionic liquid crystal, 1-dodecyl-3-ethylimidazolium iodide （C12EImI）, and an ionic liquid, 1-decyl-3- ethylimidazolium iodide （Cl0EImI）, have been synthesized, characterized and employed as the electrolyte for dye-sensitized solar cells （DSSC）. The physicochemical properties show that a smectic A （SmA） phase with a lamellar structure is formed in CIzEImI. Both C^2EImI and Cl0EImI have good electrochemical and thermal stability facilitating their use in DSSC. The steady-state voltammograms reveal that the diffusion coefficient of I3- in C^2EImI is larger than that in CmEImI, which is at- tributed to the existence of the SmA phase in Ca2EImI. Because the iodide species are located between the layers of imidazo- lium cations in CjzEImI, exchange reaction-based diffusion is increased with a consequent increase in, the overall diffusion. The electrochemical impedance spectrum reveals that charge recombination at the dyed TiOJelectrolyte interface of a C12EImI-based DSSC is reduced due to the increase in I3- diffusion, resulting in higher open-circuit voltage. Moreover, both short-circuit current density and fill factor of the Cl2EImI based DSSC increase, as a result of the increasing transport of I3 in C^2EImI. Consequently, the photoelectric conversion efficiency of C^2EImI-based DSSC is higher than that of the Cl0EImI-based DSSC.

Mesomorphous structure change by tail chain number in ionic liquid crystalline complexes of linear polymer and amphiphiles

Three polymer-amphiphile complexes were prepared by combining poly（allylamine hydrochloride）（PAH） with the potassium salt of mono-,di-,and trisubstituted benzoic acid dendrons（4-octyloxybenzoic acid,3,5-dioctyloxybenzoic acid,and 3,4,5- trioctyloxybenzoic acid）.The solid structure and properties were monitored with FT-IR,XRD,TG,DSC,and polarized optical microscope（POM）.Difference in the tail chain number of the dendritic amphiphile induced two different mesomorphous structures： lamella for the mono-,disubstituted dendron containing complexes and hexagonal column for the trisubstituted dendron containing complexes.These corresponded to the ionic thermotropic liquid crystal SmA andΦ_h phases,respectively.This finding is significant for design of functional nanostructures based on the ionic complexation of polymers and amphiphiles.

Lattice Energy Estimation for Complex Inorganic Ionic Crystal

A novel connectivity index ^mG based on adjacency matrix of molecular graphs was proposed as follows： ^mG = ∑（gi·gj·g…）^0.5. The element gi of adjacency matrix was defined as gi=（1＋Zi^1.4）/（1＋ri^1.4）, where Zi and ri are the charge number and the thermochemical radius of ion i respectively, and the radii ri for metal ions are taken to be the Goldschmidt radius. The regression analysis by the connectivity index 1G can provide a high-quality QSPR model for the lattice energies of 245 complex inorganic ionic crystal samples. The results imply, that the lattice energies may be expressed as a linear model of the connectivity index 1G. For the linear model the correlation coefficient r and the standard error s are 0.9998 and 228.72 kJ/mol, respectively. The cross-validation by the leave-one-out method demonstrates that the model is highly reliable from the point of view of statistics.

Ionic Bent Shape Ternary Facial Amphiphiles

Novel bent shape tenary facial amphiphilic imidazolium ILC which consist of a ^-conjugated bent aromatic cores （2,5-dithiophenylethynyl phenyl bent core）, two terminal poliphilic alkyl chains and lateral n-alky chain terminated by an imidazolium bromide unit were synthesized by using Kumada and Sonogashira coupling reactions as key steps and both their thermotropic and lyotropic mesophase behaviors were studied by POM, DSC and XRD. Columnar phases were found in these compounds, a hexagonal cylinder model with core shell structure is supposed for the columnar phase formed by compound 1/8. Our study may provide a new strategy for designing new LC functional material.

Phase behaviors of ionic liquids attributed to the dual ionic and organic nature

Ionic liquids(ILs),also known as room-temperature molten salts,are solely composed of ions with melting points usually below 100℃.Because of their low volatility and vast amounts of species,ILs can serve as’green solvents’and’designer solvents’to meet the requirements of various applications by fine-tuning their molecular structures.A good understanding of the phase behaviors of ILs is certainly fundamentally important in terms of their wide applications.This review intends to summarize the major conclusions so far drawn on phase behaviors of ILs by computational,theoretical,and experimental studies,illustrating the intrinsic relationship between their dual ionic and organic nature and the crystalline phases,nanoscale segregation liquid phase,IL crystal phases,as well as phase behaviors of their mixture with small organic molecules.

Novel redox-active ionic thermotropic liquid crystalline complexes of polyelectrolyte and ferrocenyl surfactants

Redox-active polyelectrolyte-surfactant complexes（PSC） were prepared via the ionic self-assembly of sodium poly（styrenesulfonate） （PSS） and ferrocenyl surfactant,（11-ferrocenylundecyl）trimethylammonium bromide（FTMA） in aqueous solution. The PSS-FTMA complex exhibited an ordered interdigitated monolayer mesomorphous structure with the long period of d = 3.13 nm,and was in the ionic thermotropic liquid crystal SmA state at room temperature.Interestingly,in the solid complex, the ferrocenyl moieties formed H-aggregation showing an increase in theπ-π~＊ energy transfer of cyclopentadienes in the ferrocene moieties as known from the blue-shift in the UV spectrum.The complexes showed higher thermal stability compared with their components due to the ionic interaction.The PSS-FTMA film had a good redox reversibility,which promised to be used in electrochemical sensors.

Highly redispersible CNT dough for better processiblity

Carbon nanotubes(CNTs)have received considerable attention for their excellent thermal and electrical conductivity as well as scalable production.However,CNT dispersions are prone to settling and have a short shelf time,especially under high concentration,which significantly hinders their further processing and increases transportation costs.Here,we report a highly concentrated CNT dough enabled by ionic liquid crystal(ILC)as auxiliaries.Benefiting from the temperature-controlled physical transformation of the ILC,the CNTs of the powder state are successfully transferred to highly processable dough with excellent electrical conductivity,flame retardancy,and outstanding redispersibility even after 180 days of storage.In particular,the CNT dough exhibits excellent self-healing properties and good reshapable capability.Various bulk form CNT derived from the ILC armored CNT dough are realized by facile processing technique.Hybrid nanocomposite papers with ANF nanofiber exhibited excellent photothermal conversion and Joule heating properties.The redispersible CNT doughs presented here promise to revolutionize traditional CNT powder and dispersions as the primary raw material for building CNT-based architectures and facilitate the large-scale application of CNTs.