High-voltage electroconduction in molten chlorides of alkaline-earth metals

Effects of high-voltage pulses on electroconduction of molten chlorides of alkaline-earth metals and their mixtures with potassium chloride are studied experimentally. It is established that the electroconductivity of the melts subjected to the pulses increases proportionally to the voltage amplitude and the number of activating pulses in a pulse series. Oscillatory relaxation of nonequilibrium melts is discovered.     

Effect of MgO nanoparticles on ionic conductivity and electrochemical properties of nanocomposite polymer electrolyte

This paper analyzes the comparison between the performances and morphologies of the PMMA gel and composite electrolyte membrane with nanosized MgO particles. These polymer electrolytes were studied in detailed using XRD, DSC, SEM and AC impedance analysis. The conductivity enhancement has been attributed to the addition of ceramic filler that yields a significant increase of surface to volume ratio related to the decrease in glass transition temperature values in the composite polymer electrolyte. Good interfacial stability at the electrode/electrolyte interface resulted on account of the improved ion dissociation by ceramic filler and a rise in the room temperature conductivity (8.14 × 10⁻³ S cm⁻¹) due to the iono-covalent or Lewis acid–base bonds to the ions and ether oxygen base groups was also observed. Further enhancement of conductivity has been observed on MgO surface, as Lewis-acidic sites interact with both PMMA and ClO₄⁻ ions. The percentage of swelling was found to increase with increasing soaking periods upto 12 h. Beyond that soaking period, it was found that there was a negligible increase in the % of swelling.     

Effects of High-voltage Pulse Electric Field Treatment on the Structure Stability of Konjac Glucomannan

Structures of KGM treated in two high-voltage pulse electric fields were characterized by infrared spectroscopy,Raman spectroscopy,X-ray diffraction and so on.The results showed that intermolecular hydrogen bonding interactions of KGM were reduced after being treated with high-voltage pulse electric field,but there was no significant effect on its fiber chain form and thermal characteristics.Results of the study can provide a useful reference for further study on the structure and property of KGM,and especially can provide theoretical basis for the effect of physical field on the foodstuff deep processing related to KGM.     

High-voltage activation and dynamics of conductivity relaxation in a binary NaHSO<Subscript>4</Subscript>-KHSO<Subscript>4</Subscript> system

The effect of high-voltage pulses on the conductivity of the binary system of protonic solid NaHSO₄-KHSO₄ electrolyte and its melt with the NaHSO₄ content of 25, 50, 75 mol % is studied. The conductivity of both the solid electrolyte and its melt grows at the increase in the electric field intensity and tends to saturation in the melt. The highest relative conductivity increase of molten electrolyte (T = 469 K, 25 mol % NaHSO₄) reaches 296% and that of the solid electrolyte (T = 408 K, equimolar composition) before breakdown phenomena is 78%. The breakdown conductivity increases by several orders of magnitude. The conductivity relaxation processes after high-voltage pulsed discharges are studied. Relaxation times τ for nonequilibrium carriers are calculated that are of the order of 10³ to 10⁴ s. This time is lower for solid electrolytes, as compared to that in the corresponding melts.     

Influence of nanodisperse Li3N on the electrochemical properties of a polymeric electrolyte

Influence of additives fine-dispersed powder Li₃N on electrochemical properties polymer gel- electrolyte and its interface with metal Lithium is investigated. Lithium nitride was received by reaction of dry nitrogen with metal Lithium within 5 hours at 100°C, and then it was crushed on a spherical grinding mill in an inert atmosphere. The size of particles has made 100 nanometers. Dependence of an electrochemical impedance of polymer electrolyte on the added amount of fine-dispersed powder of Li₃N—0.5 w/w% and 1.0 w/w% was measured. It is found, that introduction 0.5 w/w% Li₃N improves volume conductivity of polymer electrolyte in 2.4 times, but further increase amount of Li₃N (1.0 w/w%) does not change this characteristic. On interface with metal Lithium, on the contrary, Li₃N—additive increases charge transfer resistance in 1.5 times that speaks about difficulty of electrochemical reaction Li⁺ + e ? Li at presence Li₃N.     

Effect of pressure and temperature on chromophore reorientation in a side-chain nonlinear optical polymer

Second harmonic generation (SHG) was used to measure the temperature dependence of the reorientation activation volume of the side-chain copolymer poly(disperse red 1 methacrylate-co-methyl methacrylate) (DR1-MMA). The decay of the SHG signal from poled films of DR1-MMA was recorded at hydrostatic pressures up to 3060 atm and at different temperatures between 25°C below the glass transition temperature (T_g) to 35°C above it. The activation volume, ΔV^*, decreased with increasing temperature. The data suggests that the coupling between chromophore reorientation and the long-range motion of the polymer is stronger for the DR1-MMA side-chain system than in previously measured guest–host systems. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2793–2803, 1998     

Effect of carbon black type and concentration on the performance of semiconductive shielding material of high-voltage cable

Semiconductive shielding layer as an important part of high-voltage cable, its performance directly affects the safe operation and the service life of the cable. Carbon black (CB) is the main conductive filler of shielding materials, and its type and concentration directly affect the performance of the shielding layer. In this paper, CB-A with higher structure and CB-B with lower structure were used as conductive fillers and EBA was chosen as the matrix resin to prepare the shielding materials. The CB concentrations of the shielding materials were 35, 45, and 55 phr. The influences of CB type and concentration on the physicochemical, electrical, thermal and mechanical properties of the shielding materials were investigated. The research shows that when the CB types are the same, the higher the concentration of CB, the more intensive the CB network in the shielding material, and the more serious the CB agglomeration phenomenon. With increasing CB concentration, shielding materials show a decreasing trend of volume resistivity, an increasing trend of thermal conductivity, and a decreasing trend of mechanical properties. When the CB concentration is the equal, the CB-A has better dispersion in the matrix resin, CB-A/EBA shielding material has lower volume resistivity and weaker PTC effect, CB-A/EBA shielding material has higher thermal conductivity at low temperature and CB-B/EBA shielding material has higher thermal conductivity at high temperature, CB-A/EBA shielding material has better mechanical properties. A comprehensive comparison shows that CB-A/EBA shielding material with a concentration of 45 phr has excellent overall performance, with volume resistivity of 15.3 and 68 Ω·cm at 25°C and 90°C, respectively. The thermal conductivity is 0.434 W/(m K) at room temperature and 0.536 W/(m K) at 90°C. The stress is 31.08 MPa and the strain is 570.2%. This work has important reference for the selection of conductive fillers and performance improvement of semiconductive shielding materials.     

Monitoring the mechanical properties of the solid electrolyte interphase(SEI) using electrochemical quartz crystal microbalance with dissipation

Stable solid electrolyte interphase(SEI) has been well established to be critical for the reversible operation of Li(ion) batteries,yet our understanding of its mechanical properties currently remains incomplete.Here,we used an electrochemical quartz crystal microbalance combined with dissipation monitoring(EQCM-D) to investigate SEI formation.By quantitatively estimating in-situ,the change in mass,shear modulus,and viscosity of the SEI,we show that the SEI formation in propylene carbonate(PC)-and ethylene carbonate/diethyl carbonate(EC/DEC)-based electrolytes involves the growth of a rigid laye r followed by a viscoelastic layer,whereas a distinct "one-layer" rigid model is applicable to the SEI formulated in tetraethylene glycol dimethyl ether(TEGDME)-based electrolyte.With the continuous formation of the SEI,its shear modulus decreases accompanied by an increase in viscosity.In TEGDME,the lightest/thinnest SEI(mass lower than in PC by a factor of nine) yet having the greatest stiffness(more than five times that in PC) is obtained.We attribute this behavior to differences in the chemical composition of the SEIs,which have been revealed by tracking the mass-change-per-mole-of-electrontransferred using EQCM-D and further confirmed by X-ray photoelectron spectroscopy.     

Effect of electrochemical processing of a γ-butyrolactone-based electrolyte on the cyclability of lithium electrodes

Effect of a preliminary electrolysis of electrolyte on the lithium electrode cyclability in a 1 M LiC1O₄ solution in γ-butyrolactone is studied. On its repeated cycling in the same electrolyte, the lithium electrode’s efficiency decreases and the overvoltage of cathodic and anodic processes considerably increases. Soluble products of electrochemical destruction of the electrolytic system accumulate in solution during the lithium electrode cycling, the products being prone to polymerization. In the presence of these products, the lithium passivation rate increases and the cycling efficiency decreases significantly. It is concluded that the soluble products of the destruction are oligomers formed during electrochemical polymerization of γ-butyrolactone     

Effect of ampere force on electrolyte flow and current passing due to EMF generation in electrochemical cell rotating in magnetic field

An Ampere force acts in the rotating electrochemical cell, which is located in the magnetic field. This force causes an electrolyte flow directed oppositely to the direction of cell rotation. The effect of Ampere force on the distribution of hydrodynamic velocity in the gap between two cylindrical electrodes of rotating cell is theoretically analyzed. Under certain simplifying assumptions, an equation is obtained for calculating the current passing in the cell by action of potential difference, which arises in the cell due to the Lorentz force taking into account the Ampere force.     

Synthesis,structure and electrochemical properties of a family of organoruthenium complexes

Reaction of N-(2′-hydroxyphenyl)benzaldimines (abbreviated in general as H₂L-R, where R stands for the para-substituent in the benzaldehyde fragment and H stands for the dissociable hydrogen atoms) with [Ru(PPh₃)₂(CO)₂Cl₂] affords a family of organoruthenium complexes of the type [Ru(PPh₃)₂(CO)(L-R)] where the N-(2′-hydroxyphenyl)benzaldimine ligand is coordinated to the metal center as tridentate C,N,O-donor. Structure of a representative complex has been determined by X-ray crystallography. All the [Ru(PPh₃)₂(CO)(L-R)] complexes are diamagnetic, and show characteristic ¹H NMR signals and moderately intense MLCT transitions in the visible region. Cyclic voltammetry of the [Ru(PPh₃)₂(CO)(L-R)] complexes shows a reversible Ru(II)–Ru(III) oxidation within 0.38–0.68 V versus SCE, followed by an irreversible oxidation of the coordinated benzaldimine ligand within 1.09–1.27 V versus SCE. An irreversible reduction of the coordinated benzaldimine ligand is also observed near −1.1 V versus SCE. Potential of the Ru(II)–Ru(III) oxidation is observed to be sensitive to the nature of para-substituent R.     

Dielectric properties of a strongly polar nematic liquid crystal compound doped with gold nanoparticles

This study focuses on the electrical characteristics of a strongly polar nematic liquid crystal, Hexyloxy-cyanobiphenyl (6OCB), doped with a low concentration (2% by weight) of citrate buffer stabilised gold nanoparticles (GNPs) at low frequencies between 20 Hz and 35 MHz. The doped samples have lower values of nematic–isotropic transition temperature, permittivity (both parallel and perpendicular to the field direction) and dielectric anisotropy; however, relaxation time and activation energy were increased. The observed results could be explained on the basis of weakly anisotropic nature of GNPs and a local rearrangement of liquid crystal molecules surrounding the nanoparticles. Moreover, a complimentary suggestion on a possible change in the dipole–dipole correlation is made to explain the difference in changes (qualitative and quantitative) observed for permittivity of the host nematic liquid crystal doped with GNP. Temperature dependent dielectric relaxation studies indicate an increase in viscosity and potential barrier; and hence a change in strength of inter-molecular and intra-molecular interactions is suggested.     

甘氨酸电解液添加剂对水系锌离子电池电化学性能的影响

水系锌离子电池因其高安全性、高容量、低价格等优点,有望成为下一代规模储能设备。然而,副反应、锌枝晶和有限的使用寿命阻碍了其实际应用。我们将电解质添加剂甘氨酸(Gly)引入到常规水系ZnSO₄电解质中。Gly中的极性基团(—COOH和—NH₂)可以调节Zn²⁺的溶剂化结构,从而重新分配Zn²⁺的沉积以避免枝晶和副反应发生。结果表明,在ZnSO₄电解质中添加50 mmol·L^-1的Gly后(ZnSO₄-Gly),Zn||Zn对称电池在1 mA·cm^-2和1 mAh·cm^-2下,表现出良好的循环寿命(3 000 h),明显高于使用ZnSO₄电解质的性能(300 h)。以ZnSO₄-Gly为电解液的Zn||MnO₂全电池,在比电容和倍率性能方面比无添加剂器件表现得更好。     

Effect of cathodic electrolyte on the performance of electrochemical hydride generation from graphite cathode

The classic silver diethyldithiocarbamate (SDDC) spectrophotometric procedure for arsenic determination has been used for investigation of the effect of cathodic electrolyte on the performance of electrochemical hydride generation (HG) from graphite cathode. The results of this study show that the presence of a soft metal ion such as Cd(II), Sn(II) and/or Zn(II) in the acidic cathodic electrolyte can increase effectively the efficiency of electrochemical hydride generation and decrease the effect of interferences. The possible mechanisms of these effects have been discussed in detail. The parameters related to the electrochemical hydride generation were investigated. Also the characteristic data of the electrochemical hydride generation and common hydride generation by NaBH₄ were compared. Under optimised conditions, the system is selective to As(III) and total inorganic analyses can be performed after a pre-reduction stage prior to electrochemical hydride generation. This will allow the differential determination of inorganic arsenic species. The method is appropriate to the determination of 4-40 μg of each arsenic species.     

Effect of Molecular Weight on Enthalpy Relaxation in Syndiotactic Poly(Methyl-Methacrylate)

The structural relaxation behaviour of narrow fractions (M_w/M_n < 1.1) of syndiotactic poly(methyl methacrylate) with molecular masses ranging from 2,000 to 200,000 Daltons have been studied by DSC with two classical procedures, namely: the rate of cooling and the isothermal approaches. The apparent activation energy (Δh*) of enthalpy relaxation was evaluated from the dependence of the glass transition temperature on the cooling rate while a comparison of the apparent relaxation rates was appraised from the enthalpy loss by annealing the different samples at the same level of undercooling (T_a = T_g − 10 °C). As expected, the increase of molecular weights gives rise to both a continuous increase of Δh* and a decrease of the apparent isothermal relaxation rate. More interestingly, both Δh* and the apparent isothermal relaxation rate showed abrupt changes around the syndiotactic PMMA entanglement mass (M_e ).     

Effect of pressure and temperature on chromophore reorientation in a new syndioregic main‐chain hydrazone nonlinear optical polymer

Second harmonic generation (SHG) was used to measure the temperature dependence of the reorientation activation volume (ΔV*) of a syndioregic main‐chain hydrazone (SMCH) nonlinear optical polymer. The decay of the SHG signal from poled films of SMCH was recorded at hydrostatic pressures up to 2924 atm and at temperatures between 25 °C below the glass‐transition temperature (T_g) to 20 °C above it. ΔV* for pressures less than 500–1000 atm and T > T_g decreased as the temperature was increased. For pressures greater than 1000 atm, ΔV* was essentially constant for all temperatures. In addition, the size of ΔV* indicated that the chromophore in this main chain was internally flexible. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 895–900, 2001     

Enhancing electrochemical preparation of polyaluminum chloride by a magnetic field

A novel effective method for preparing polyaluminum chloride (PAC) with high content of Al₁₃ polymer through conventional electrolysis coupled with rare earth Nd-Fe-B magnetic field was introduced. The content of Al₁₃ polymer in PAC synthesized by this method was highly influenced by the electrobath voltage (E), the magnetic flux density (B), the current density (i) and the distance between the two adjacent electrodes (d_adj). A total aluminum concentration (Al_T) in the PAC solution of 0.8 mol l⁻¹ was obtained when the E, B and i was 2.2 V, 0.4 T and 3.2 A dm⁻², respectively. The optimum d_adj and circulating flow (Q_f) were 20 mm and 23.7 l h⁻¹. With accelerated mass transfer rate by external magnetic field and high Q_f, this process had the advantages of forming more Al(OH)₄⁻ as the precursor of Al₁₃ polymer and inhibiting the concentration polarization more obviously than conventional electrolysis process. Under the optimum conditions, the amount of Al₁₃ polymer in PAC accounted for 82.3% of the Al_T (Al_T = 0.8 M, basicity = 2.2), which was higher than that of PAC prepared by other methods.     

Effect of convective channel-to-channel mass flow in a polymer electrolyte fuel cell

The effect of convective channel-to-channel mass flow on the local performance of a polymer electrolyte fuel cell (PEFC) air cathode is determined experimentally by using submillimeter resolved current density distribution measurements in channel and land areas. A special cell is employed, where the two parallel channels of the cathode flow field can be operated at different pressure. For isobaric operation of the channels (Δp = 0 mbar), the lateral current density distribution shows a distinct minimum in the land area between the channels as diffusive mass transport becomes limiting at a higher cell polarization. Toward higher Δp, the local cell performance in the land area improves initially as a result of an improving convective channel-to-channel mass flow. However, as the pressure difference exceeds a value of 10 mbar, no noteworthy additional benefit is observed with further increasing Δp. Under these conditions, the convective mass flow provides an abundant reactant supply in the land area and, since reactant depletion is no longer limiting, the lateral current density distribution is primarily governed by the local ohmic resistance. As a result, the current density exhibits a maximum in the land area, where the local ohmic resistance shows a minimum.     

Effect of magnetic field on enthalpy of solution of KCl in water

The enthalpies of solution of potassium chloride (KCl) in water and magnetically treated water (magnetized water) have been measured at 298.15 K using a LKB-8700 precision solution calorimeter. From the experimental results, it was observed that the effect of magnetic field on the enthalpy of solution is measurable. This is probably due to the distortion of the hydrogen bond of water resulting from magnetic treatment.