Application of ionic liquids-based Li-ion battery electrolyte andimprovement of electrochemical properties

近年来锂离子电池在动力电池方面被寄予厚望,但安全性是制约其应用的关键之一,而其安全性与电解液性质密切相关。离子液体具有不可燃、不挥发、热稳定性好等优点,可作为电解液以替代传统有机溶剂应用于锂离子电池中。基于现有研究,本文阐述了各类离子液体作为锂离子电池电解液的优异性和不足点,进而综述了各种针对离子液体自身不足采取的性能改进方法,并对该方向的进一步研究进行了展望。     

Electrodeposition of bismuth, tellurium, and bismuth telluride thin films from choline chloride–oxalic acid ionic liquid

This article presents a series of preliminary results regarding the electrodeposition of bismuth, tellurium, and bismuth telluride films at 60 °C from ionic liquids, containing a mixture of choline chloride and oxalic acid (ChCl–OxA). Ten millimolar concentration solutions of BiCl₃ and TeO₂ were used as precursors in this supporting electrolyte. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to demonstrate the deposition processes on Pt and Cu electrodes. Long-time electrolyses (30–120 min) performed at 60 °C with potential control (between ?0.22 and ?0.37 V vs. Ag reference electrode) have resulted in films deposited on copper substrate. Film surfaces were studied by scanning electron microscopy and analyzed by energy dispersive X-ray spectroscopy. The results of this study show that ChCl–OxA ionic liquid may be considered as a promising substitute of aqueous baths for Bi, Te or Bi₂Te₃ film plating.     

Physicochemical properties of amide–AlCl_3 based ionic liquid analogues and their mixtures with copper salt

The physicochemical properties of three different amide–AlCl_3 based ionic liquid(IL) analogues and their mixtures with copper salt, such as conductivity, viscosity, density and isobutane solubility were determined over a wide range of temperatures.The effects of amide structure, amide/AlCl_3 molar ratio and CuCl modification on these physicochemical properties were investigated.Results showed that the conductivity of amide–AlCl_3 based IL analogues was much lower than that of traditional Et_3NHCl–AlCl_3 IL with same ligand/AlCl_3 molar ratio due to incomplete splitting of AlCl_3, whereas the density and viscosity of amide–AlCl_3 based IL analogues were slightly higher.The viscosity of amide–AlCl_3 based IL analogues was closely related to the amide structure,and followed the order of DMA–AlCl_3AA–AlCl_3NMA–AlCl_3 with same amide/AlCl_3 molar ratio.Meanwhile,the density of amide–AlCl_3 based IL analogues ranked in the following order: AA–AlCl_3NMA–AlCl_3DMA–AlCl_3.Increasing the amide/AlCl_3 molar ratio decreased the conductivity and density, while increased the viscosity.The solubility experiment indicated that the isobutane solubility in NMA–AlCl_3 was highest than that in two other IL analogues.Under the modification of CuCl, the conductivity, viscosity and density of these IL analogues increased, whereas the isobutane solubility decreased.These results provide the foundation for the development of a suitable IL analogue catalyst for isobutane alkylation.     

Enhanced ion transport in polymer–ionic liquid electrolytes containing ionic liquid-functionalized nanostructured carbon materials

An effective chemical strategy for the synthesis of polymer–ionic liquid (IL) electrolytes with ion-conducting channels, physically modulated by variously dimensioned IL-functionalized carbon materials (IL-FCMs) including carbon black (CB), multi-walled carbon nanotubes (MWCNT) and reduced graphene oxide sheets (RGO) is reported, enabling a fundamental understanding of the relationship between carbon structures and ion transport behavior. The risk of electrical shorts is eliminated by the presence of IL groups on the surfaces of CMs and only minimal amounts of the IL-FCMs (⩽1.0 wt.%) in the polymer/IL composite electrolytes (e.g., polymer matrix filled with 1.0 wt.% IL-FCMs has a conductivity of ∼10⁻⁷ S cm⁻¹ at 100 °C). Increase in ion transport within the reorganized ion channels of the composite polymer electrolytes (CPEs) is confirmed by the enhanced ionic conductivity and low activation energy for through-plane and in-plane ionic conduction at different temperature (40–160 °C). Maximum improvement in the ionic conductivity (150–300% at 100 °C) can be achieved by optimizing the carbon structure and the loading ratio, which leads to highly ionic conductive polymer/IL composite electrolytes for practical applications.     

MCM-36 zeolites tailored with acidic ionic liquid to regulate adsorption properties of isobutane and 1-butene☆

Adsorption properties of an adsorbent or a catalyst towards adsorbates are crucial in the process of adsorption separation or catalytic reaction. Surface morphology and structure of adsorbents have a significant impact on the adsorption properties. In this study, a novel acidic ionic liquid, 1-butyl-3-(triethoxysilylpropyl)imidazolium hydrogen sulfate(i.e., [BTPIm][HSO_4]), was synthesized and subsequently grafted onto the MCM-36 zeolite for the regulation of its adsorption properties towards isobutane and 1-butene. The resultant [BTPIm][HSO_4]-immobilized MCM-36(i.e., MCM-36-IL) was characterized by FT-IR, XPS, XRD, SEM, TG/DTG and N_2 adsorption–desorption measurement. It was found that the specific surface area, micropore volume and mesopore volume of the MCM-36 support underwent a reduction upon the immobilization of ionic liquid,while the surface density of acid increased from 0.0014 to 0.0035 mmol·m~(-2). The adsorption capacity of isobutane and 1-butene on the MCM-36-IL was determined by a static volumetric method. Results demonstrated that the interaction between isobutane and MCM-36-IL was enhanced and the interaction between 1-butene and MCM-36-IL was reduced. As a result, a tunable adsorption ratio of isobutane/1-butene on MCM-36 was achieved.With the increase in surface density of acid and the tunable adsorption ratio of isobutane and 1-butene on the functionalized MCM-36, the acidic ionic liquid-immobilized zeolites are beneficial to obtain an improved reaction yield and a prolonged catalyst life in the reactions catalyzed by solid acid.     

Structure and surface properties of Al2O3–TiO2 ceramic coated AZ31 magnesium alloy

Magnesium and its alloys are the engineering materials which have the potential ability to be able to used widely particularly in the automotive, aerospace and in the biomedical sectors, especially thanks to their features such as lightness, specific strength that they have and biocompatibility. However, due to their poor wear resistance and corrosion resistance, the areas of usage are being restricted. This situation prevents Mg alloys to be used without any surface protection despite their good mechanical properties such as high strength/weight ratio. In this study, plasma spraying method is used to improve the poor corrosion resistance of AZ31 Mg alloy. Al₂O₃–13 wt% TiO₂ (AT13) and Al₂O₃–40 wt% TiO₂ (AT40) composite ceramic coatings were coated successfully on the surfaces of AZ31 Mg samples. The wear properties of the AT13 and AT40 coated samples were investigated for tribological applications. Surface morphology and microstructure of the duplex treated samples were analyzed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The microhardness value of the uncoated AZ31 Mg alloy is 40±3 HV_0.1, while the microhardness values of the AT40 and AT13 coatings are enhanced to 800±39 HV_0.1 and 1500±35 HV_0.1, respectively.     

An imidazolium iodide–containing hyperbranched polymer ionic liquid that improves the performance of dye-sensitized solar cells

In this study, we synthesized an imidazolium iodide–containing hyperbranched polymer ionic liquid (HPIL) for use as the gel electrolyte of dye-sensitized solar cells (DSSCs). We incorporated HPIL at various contents (4, 8, and 15 wt%) in a solvent-free ionic liquid (1-propyl-2,3-dimethylimidazolium iodide and 1-ethyl-3-methylimidazolium tetrafluoroborate)–based quasi-solid gel electrolyte (IL-A) and a solvent (3-methoxypropionitrile)-based fluid gel electrolyte (IL-B). After fabricating N719 dye–based DSSCs incorporating the HPIL/IL-A and HPIL/IL-B gel electrolytes, we recorded the electrochemical impedance spectra and measured the photovoltaic (PV) performance of these devices. In the dark, the DSSCs incorporating HPIL exhibited higher charge recombination resistances at the interface between TiO₂/dye and the electrolyte. This high recombination resistance suppressed the dark current and improved the PV performance of the devices incorporating HPIL. The DSSCs fabricated from the HPIL/IL-B gel electrolyte displayed higher photo-conversion efficiency, while those fabricated from the HPIL/IL-A gel electrolyte provided superior operational stability. Under AM 1.5 illumination (100 mW cm^?2), we measured a photo-conversion efficiency of 7.18 %, a short-circuit current density of 16.09 mA cm^?2, an open-circuit voltage of 0.69 V, and a fill factor of 0.65 for the DSSC incorporating the gel electrolyte HPIL/IL-B (4:96, w/w). The DSSC incorporating the gel electrolyte HPIL/IL-A (15:85, w/w) exhibited good operational stability, retaining approximately 93 % of its original efficiency after 500 h.

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Graphical abstract An imidazolium iodide-containing hyperbranched polymer ionic liquid HPIL was synthesized for use as the gel electrolyte of dye-sensitized solar cells.

     

Research progress of diamondoids（Ⅰ）Structure and properties

金刚烃是由多个环己烷构成的饱和笼状烃,此类有机化合物的分子式为C_4n+6H_4n+12。金刚烷则是最小的金刚烃化合物（即n=1时）,其C原子骨架类似于金刚石的一个晶格单元。由于其独特的笼状结构和特殊的化学、物理和药理学性质,因此其逐渐成为研究的热点。本文介绍了金刚烃的结构、命名、性质,重点介绍了金刚烃的化学性质及其衍生物的合成。     

Synthesis of ［EMIM］Br-AlCl3 ionic liquid

采用N-甲基咪唑、溴乙烷、AlCl₃常规回流法以及微波法合成离子液体,研究［EMIM］Br中间体的产率;采用量子化学方法计算离子液体结构,明确合成反应的机理;通过紫外光谱和红外光谱表征［EMIM］Br-AlCl₃离子液体的结构;测试离子液体的密度、电导率等性质。结果表明：常规回流法以N-甲基咪唑和溴乙烷为原料,在70℃温度下反应5 h,反应产率为87.9%;微波法反应时间1000 s,产率为94.2%;40℃下密度为1.46 g·cm^-3,电导率为21 S·m^-1;用DFT B3LYP 量子化学计算方法研究离子液体的构型,离子液体的合成反应遵循SN2反应机理;紫外光谱和红外光谱表征了［EMIM］Br和AlCl₃/［EMIM］Br离子液体的结构。     

Effect of titanium–magnesium catalyst morphology on the properties of polypropylene upon propylene polymerization in a liquid monomer

The effect of the particle size of an IK-8-21 domestic titanium-magnesium catalyst on the properties of polypropylene (PP) produced during the polymerization of propylene in a liquid monomer is studied. Catalysts with particle sizes of 20 to 64 μm are shown to have high activity and identical sensitivity to hydrogen and allow PP to be obtained with a narrow distribution of particles over size, high isotacticity, and close values of crystallinity, melting temperature, and physicomechanical properties. A slight decrease in the activity and bulk density of PP powder is observed when the average size of catalyst particles is increased from 20 to 43 μm. A more notable reduction in the activity and bulk density of PP powder is observed for catalyst with particle sizes of 62 to 64 μm. IK-8-21 catalyst is not inferior to its foreign analogues with respect to the properties of the resulting PP.     

Liquid–liquid extraction of hydroxytyrosol,tyrosol, and oleuropein using ionic liquids

ABSTRACT

Hydroxytyrosol (HT), tyrosol (TY), and oleuropein (OL) are valuable compounds that can be obtained from olive oil production waste. This study implemented liquid–liquid extraction to obtain HT, TY, and OL from model solutions using two organic solvents, namely, ethyl acetate and n-butyl acetate, and three ionic liquids (ILs), namely, [P_6,6,6,14][Tf₂N], [P_6,6,6,14][DCA], and [omim][Tf₂N]. [P_6,6,6,14][DCA] showed the best performance, with extraction efficiencies of 92%, 96%, and 83% for HT, TY, and OL, respectively. [omim][Tf₂N] showed the highest selectivity in the extraction of TY. Comparisons of the results of a proposed mathematical model with experimental data yielded errors lower than 0.5%.     

Effects of washing and calcination–milling on ionic release and surface properties of yttria stabilized zirconia

Crystallographic features, physical properties and ionic release from yttria stabilized zirconia (YSZ) in suspension were studied by means of XRD, TEM, light-scattering particle size, BET, ICP and zeta potential analysis. It was found that Zr, Y, Na, and to a lesser extent Ca, Hf and Pd leach from 8 mol% YSZ powder. The impurities present increase the zeta potential of suspensions made from as-received YSZ. A trace amount of tetragonal phase observed in 8 mol% YSZ persists following washing and calcination–milling. Dislocations and crystallographic defects together with fractured crystals which form during milling of the calcined powder should lead to the formation of more broken bonds; as a result the surface of the particles can support higher surface charge density. Washing and calcination–milling lead to a shift of the isoelectric point of 8 mol% YSZ from pH 8.4 to pH 6.3 and 6.8, respectively. Due to higher chemical stability and previously shown positive impacts on microstructure and performance of fuel cells, use of calcined YSZ can be more advantageous than as received powder.     

Effect of powder–liquid ratio and admixture on properties of metakaolin-based geopolymer coating

Protective coating is one of the effective ways to help concrete structures resist environmental erosion. However, most of the existing coating materials are organic compounds, which have the disadvantages of poor durability and high energy consumption. In this study, metakaolin with excellent durability was used as the main raw material, and a flexible and waterproof ethylene-vinyl acetate emulsion was added to improve the high brittleness characteristics of metakaolin, resulting in a metakaolin-based geopolymer coating material. Through tests such as water absorption, hardness, gloss, and tensile properties, we investigated the effects of the powder–liquid ratio and the type and amount of admixture on the properties of the coating. The results show that the coating exhibits better performance when the powder-to-liquid ratio is 0.6. Based on this, it was found that the optimal dosage of water-reducing agent, coupling agent, and defoamer was 0.7%, 0.3%, and 0.3%, respectively.     

Modeling vapor–liquid equilibrium and liquid–liquid extraction of deep eutectic solvents and ionic liquids using perturbed-chain statistical associating fluid theory equation of state. Part II

This study aims to use perturbed-chain statistical associating fluid theory (PC-SAFT) to describe the phase behavior of systems containing deep eutectic solvents (DESs) and ionic liquids (ILs). The DESs are based on tetrabutylammonium chloride and tetrabutylammonium bromide as hydrogen bond acceptors, and levulinic acid and diethylene glycol as hydrogen bond donors in the mole ratio of 1:2 and 1:4, respectively. Predictions of phase equilibria by PC-SAFT were compared with the results of COnductor like Screening MOdel for Real Solvents (COSMO-RS) and non-random two-liquid (NRTL). In this work, low viscosity ether- and pyridinium-based ILs [E_nPy][NTf₂] and [C_mPy][NTf₂] were used for vapor–liquid equilibrium systems, while 1-(2-methoxyethyl)-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)-amide and 1-propyl-3-methylimidazolium bis{trifluoromethylsulfonyl}imide with n-heptane + thiophene and n-hexane + ethylbenzene were used in the liquid–liquid extraction, respectively. In the last part, the phase behavior of the mixtures of perfluoroalkylalkanes with their linear alkane counterparts was studied and compared with the SAFT-Mie pair potential.     

Synthesis and polymerization of liquid crystalline α-oxiranes containing 4-cyanobiphenyl and p-methoxyphenyl benzoate mesogenic groups

Summary Synthesis of a new series of -oxiranes having 4-cyanobiphenyl and p-methoxyphenyl benzoate mesogenic groups and phase behaviour of synthesized compounds are described. Polymerization of -oxiranes with BF₃-O(C₂H₅)₂ and Et₃Al/H₂O/Acetyl acetone as initiators was carried out. The first initiator produced the olygomers displaying liquid crystalline properties while the second one gave the crystalline polymers with high degree of polymerization.     

Modeling the thermal and physical properties of liquid and gas mixtures of Fischer–Tropsch synthesis products

The method of pseudocritical thermodynamic parameters and the Lee-Kesler equation of state are used for calculating the thermal and physical properties of a solution and a mixture of gaseous paraffins that are major constituents of Fischer-Tropsch synthesis products. The dynamic viscosities of a solution and a vapor are modeled using an original procedure proposed by the authors. A surface tension is calculated by the parachor method. The composition of liquid and gaseous products is found using a stable iteration scheme proposed by the authors. The model is tested by a comparison with experimental data from the literature for model mixtures of hydrocarbons. The results of calculating the composition and thermophysical properties of a mixture of paraffins that model the composition of synthesis products at different values of the chain propagation parameter, temperatures, and pressures are presented.     

Structure and conducting properties of La1-xSrxCoO3-δ films

La_1-xSr_xCoO_3-δ (LSCO) films have been deposited on LaAlO₃ (LAO), La_1-xSr_xGa_1-yMg_yO_3-δ/LaAlO₃ (LSGM/LAO) and yittria-stabilized zirconia (YSZ) substrates by pulsed laser deposition (PLD) for application to thin film solid oxide fuel cell cathodes. The optimum conditions for deposition were determined for the different substrates in an ambient of 80–310 mTorr oxygen pressure and at a substrate temperature range of 450 to 750°C. The films structures were analyzed by XRD, RBS and SEM. Epitaxial LSCO films were grown with (110) preferred orientation on YSZ, and with (100) orientation on LAO and LSGM/LAO. The electrical resistivity of the epitaxial LSCO films ranged from 10⁻² to 10⁻⁴ Ω cm, depending on the deposition temperature and substrate. The ionic conducting behavior of the LSCO film on YSZ was investigated by impedance measurement.     

Structure,microstructure and corrosion properties of brush-plated Cu–Ni alloy

Cu–Ni alloy coatings on copper substrate by the brush-plating process have been investigated using XRD and AFM. The X-Ray diffraction analysis revealed that the brush-plated Cu–Ni alloy was heterogeneous and composed of cubic Cu_3.8Ni phases. Uniform surface coverage of the substrate by granular morphology was observed from AFM. The corrosion protection performance of the brush-plated Cu–Ni alloy on copper substrate has been assessed using electrochemical corrosion tests. These results indicated a high charge transfer and low I _corr for the alloy system compared with copper deposits and the copper substrate.     

Structure and properties of electrodeposited Ni–Co–YZA composite coatings

The aim is to develop an economical composite coating with high thermal stability. Ni–Co alloys are found to possess better thermal, physical and mechanical properties compared to Ni. Also, oxide particles as distributed phase can impart better thermal stability. Hence, particulates of composite Yttria stabilised zirconia, a commonly used high temperature material and alumina (YZA) were reinforced in various Ni–Co alloy matrices through electrodeposition. The influence of YZA on the microhardness, tribology and corrosion behaviour of Ni–Co alloys with Co contents of 0 wt.%, 17 wt.%, 38 wt.% and 85 wt.% was evaluated. Optical and Scanning Electron Microscopy (SEM) confirmed the presence of YZA particles and Energy Dispersive X-ray Analysis (EDX) revealed the composition. Tribology testing showed that composite containing 38 wt.% Co displayed better wear resistance. It was found from the immersion corrosion studies that Ni–17Co–YZA coating displayed improved corrosion resistance. Thermal stability studies showed that Ni–85Co–YZA coating retained its microhardness at temperatures of 600 °C. Thus, these coatings can be tailored for various applications by varying the cobalt content.