Li7P3S11电解质的合成、传导及应用

固态电解质是固态电池中的关键材料,开发具有高离子电导率、高化学/电化学稳定性、电极兼容性良好的固态电解质正成为研究热点。硫化物固态电解质相较其它固态电解质具有更高的离子电导率和良好的机械加工性能等优势,是最有前景实现实用化的固态电解质之一。在众多硫化物固态电解质中,Li₇P₃S₁₁因其高的离子电导率和较低的原料成本而极具研究意义。本文首先介绍了Li₇P₃S₁₁电解质的结构、Li+传导机理及合成路径;其次,针对该电解质的电导率提高、空气/水稳定性提升、固固界面稳定性及电解质自身稳定性改善等问题,综述了目前常用的改性策略研究;再次,总结了基于Li₇P₃S₁₁电解质的全固态锂离子电池和全固态锂硫电池的构筑;最后,本文分析了Li₇P₃S₁₁电解质的研究和应用面临的挑战,并指出该电解质未来发展的趋势。     

Thermodynamic Constants of Acid-Base Equilibria in Solutions of Penicillins

The constants of acid-base equilibria in solutions of benzylpenicillin, carbenicillin, and ampicillin at 20°C were determined by pH-metric titration (supporting electrolytes 0.1, 0.4, 0.7, and 1.0 M KCl and KNO₃). The sizes of the ionic species of the penicillins in their energetically favorable conformation were determined by the PM3 semiempirical method. The thermodynamic equilibrium constants were estimated by extrapolation of the concentration constants to zero ionic strength by the Huckel equation, taking into account the calculated sizes of the ions.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 6, 2005, pp. 1049–1054.Original Russian Text Copyright © 2005 by Alekseev, Demskaya, Dodonova.     

Li2S-P2S5体系电解质及其在全固态锂离子电池中的应用研究进展

全固态锂离子电池具有安全性能好、能量密度高、工作温区广等优点,被广泛应用于便携式电子设备。固态电解质是全固态锂离子电池的关键材料之一,其中的硫化物电解质具有离子电导率高、电化学窗口宽、晶界电阻低和易成膜等特点,被认为最有希望应用于全固态锂离子电池。本文综述了Li_2S-P_2S_5体系电解质的发展状况,包括固态电解质的制备、改性、表征以及电极/固态电解质之间的固-固界面的稳定兼容问题。本文还涉及了以Li_2S-P_2S_5为电解质的全固态锂离子电池性能的研究进展。     

五种1-烷基-2,3-二甲基咪唑型离子液体的合成及作为Li/LiFeO_4电池电解液的研究

合成了五种新的1-烷基-2,3-二甲基咪唑二(三氟甲基磺酰)亚胺离子液体(alkyl-DMimTFSI).以离子液体作为Li/LiFeO4电池电解液,分别考察不同烷基(正丁基、正戊基、正辛基、异辛基和正癸基)对电解液理化性质、界面性质和电池行为的影响.结果表明离子液体的电化学窗口都可以达到5.6V(-0.4～5.2Vvs.Li+/Li),显示它们具有较好的电化学稳定性.加入碳酸亚乙烯酯作为添加剂后,离子液体电解液在Li负极形成稳定的固体电解质相界面膜(SEI),从而提高了Li负极的稳定性,保护了Li片不受腐蚀.电化学阻抗和循环伏安分析进一步揭示LiFeO4正极与离子液体电解液也有良好的兼容性.此外,研究还表明离子液体中烷基种类严重影响它们的电池行为.采用butyl-DMimTFSI和amyl-DMimTFSI电解液体系的电池充放电容量和可逆性明显优于另外三种离子液体,它们的首次放电容量分别达到145和152.6mAh/g,并表现出良好的充放电循环性能.因粘度最大,采用isooctyl-DMimTFSI电解液的电池首次放电容量仅为8.3mAh/g,但添加碳酸丙烯酯(质量比1∶1)稀释后首次放电容量上升至132.4mAh/g.     

Acid-base equilibria in solutions of cephotaxime and cephtriaxone

The concentration constants of acid-base equilibria in aqueous solutions of cephotaxime and cephtriaxone were determined pH-metrically at 20°C against the background of 0.1, 0.4, 0.7, and 1.0 M solutions of KCl and KNO₃. The thermodynamic constants of these equilibria were calculated by the extrapolation of the concentration constants to zero ionic strength according to the Hückel equation. Cephotaxime and cephtriaxone ionic form sizes were calculated by the semiempirical PM3 method for energetically favorable conformations.     

Studies on the Interaction of Lead(II) and Uranyl(II) with Methylcysteine and Penicillamine Bioactive Sulfur-Containing Ligands

Quantitative indication of a complex formation comes from the estimation of the stability or formation constants characterizing the equilibria corresponding to the successive addition of ligands. The binary equilibria of metal(II)-methylcysteine and also mixed equilibria metal(II)-methylcysteine-penicillamine are studied using paper electrophoretic technique. The method is based on the migration of a spot of metal ion with the complexones added to a background electrolyte at the pH 8.5. The stability constants of the mixed complexes Pb(II)-methylcysteine-penicillamine and UO₂(II)-methylcysteine-penicillamine are found to be 2.80 ± 0.09 and 3.40 ± 0.07 (logarithm of stability constant values) at a ionic strength of 0.1 M (HClO₄/NaClO₄) and a temperature of 35°C.__________From Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 344–348.Original English Text Copyright © 2005 by Tewari.This text was submitted by the author in English.     

Use of lithium perchlorate media in the study of protolytic equilibria

A study of the H⁺/F^– system by fluoride ion-selective electrode potentiometry over a range of ionic strengths in LiClO ₄ gives protolysis constants which differ markedly from those obtained in other media such as NaClO ₄ . This is shown to be consistent with the competitive complexation of the fluoride ion by the lithium ion. An examination of literature data indicates that lithium ion complexation is a general phenomenon and supports the conclusion that LiClO ₄ is not preferable to NaClO ₄ as a swamping electrolyte for the study of protolytic equilibria as has previously been thought.     

The thermodynamic characteristics of complex formation between calcium ions and L-leucine in aqueous solution

Complex formation of L-leucine with calcium ions in aqueous solution was studied by potentiometric titration at 298.15 K and ionic strength values I = 0.5, 1.0, and 1.5 (KNO₃). The formation of the CaL⁺ and CaHL²⁺ complex particles was established and their stability constants were determined. The enthalpies of protolytic equilibria of leucine and formation of calcium ion complexes with leucine were determined calorimetrically at 298.15 K and I = 0.5 (KNO₃). The thermodynamic characteristics of complex formation between calcium ions and L-leucine were calculated.     

Y2O3 and MgO co-doped ceria based electrolytes

Electrolytes of Ce_1-x-y Y _x Mg _y O_2-0.5x-y were prepared with citrate method and were characterized by inductively coupled plasma-atomic emission spectrometry, energy dispersive spectrometry, powder X-ray diffraction, and impedance spectroscopy. The effect of composition on the structure, conductivity, and stability of the electrolytes were investigated. When 0≤x≤ about 0.2 and 0≤y≤ about 0.05, the electrolytes were all single phase materials of ceria-based solid solution. However, when y> about 0.05, the electrolytes became two-phase materials, Y³⁺ and Mg²⁺ co-doped ceria-based solid solution and free MgO. The sample with nominal composition of Ce_0.815Y_0.065Mg_0.12O_2-d showed ionic conductivity at 973 K close to or even a little higher than that of similarly prepared Ce_0.9Gd_0.1O_1.95, but had lower cost of raw materials and a little better stability in reducing atmosphere. The existing of free MgO improved the stability of the electrolytes in reducing atmosphere, but too much free MgO reduced the conductivity.     

Influence of ion-background changes on the aquation rate of [CrCl3(H2O)3)]

The influence of change in ion background on the aquation rate constants of [CrCl₃(H₂O)₃)] was studied spectrophotometrically at 25°C over a broad range of ionic strengths (up to several moles/liter). The electrolytes KBr, KCl, NaClO₄, NaCl, NaBr, NaNO₃, HClO₄, HCl, LiClO₄, CaCl₂, LaCl₃, and ethanol were used. It is shown that the rate constant decreases with increasing electrolyte concentration in the electrolytic media (to 0.3 log unit in some of them), while increasing in ethanol media with increasing content of the alcohol.Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, 630090 Novosibirsk. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 12, pp. 2695–2699, December, 1992.     

Steady state electrolysis and isoelectric focusing

The properties of pH gradients formed by stationary electrolysis of weak mobile or fixed electrolytes are analyzed. The model uses the appropriate balance equations and those of chemical equilibria. It is shown how the equation of the current density has to be modified for considering that fraction of current that is associated with the diffusion of neutral buffer molecules within a pH gradient. Furthermore it is shown that the pH gradients themselves give rise to water production within the gradient and that essential properties of the steady state are related to chemical reactions between the electrolyte constituents. The differential equations describing the gradients of the concentration of a given component, the pH, conductivity and potential are explicitly formulated in relation to those reactions. The equations are solved numerically and the significance of the results for isoelectric focusing is discussed. The experimental conditions to reach shallow and smooth pH gradients exhibiting sufficient ionic strength are formulated.     

Volume changes for mixing the major sea salts: Equations valid to ionic strength 3.0 and temperature 95°C

Equations in the ion-interaction (Pitzer) system are derived for the volume change on mixing any combination of the sea salts NaCl, Na₂SO₄, MgSO₄, MgCl₂ at constant ionic strenth. For these mixings of different charge types, the equations include complex differences of pure electrolyte terms. Recently measured data for each of the pure electrolytes provide these pure electrolyte terms. Other recent measurements on the volume change on mixing are compared with values calculated from the equations. At 25°C there is no need to introduce the mixing terms based on differences in the interactions of ions of the same sign. At other temperatures, the agreement without the mixing terms is good, but significant improvement is obtained by inclusion of the binary mixing terms Cl,SO ₄ ^v and _Na,Mg ^v . The equations and parameters can then predict the volumetric properties of any mixed solution of these salts over the range 0–100°C and to at least 3 mol-kg^–1 ionic strength.     

Thermodynamic properties of aqueous mixtures of LiCl and Li2SO4 at different temperatures

Emf measurements were made on the cell without liquid junction: Li?ISE LiCl(m₁), Li₂SO₄(m₂) Ag/AgCl. The performances of the electrode pairs constructed in our laboratory were tested and exhibited near-Nernstian behavior. The mean activity coefficients of LiCl for the system Li⁺?Cl^??SO ₄ ^2? ?H₂O have been investigated by the emf values at temperatures of 0, 15, 35°C and constant total ionic strengths of 0.05, 0.1, 0.5, 1.0, 2.0, 3.0 and 5.0 mol·kg^?1. The activity coefficients decrease with increasing temperature and the ionic strength fraction of Li₂SO₄ in the mixtures. The thermodynamic properties are interpreted by use of Harned's empirical equations and Pitzer's ion interaction approach including the contribution of higher order electrostatic terms. The experimental results obey Harned's rule and are described by using Pitzer equations satisfactorily. The activity coefficients of Li₂SO₄, the osmotic coefficients and the excess free energies of mixing for the system in the experimental temperature range were reported.     

Application of Pitzer's Equations for Modeling the Aqueous Thermodynamics of Actinide Species in Natural Waters: A Review

A review of the applicability of Pitzer's equations to the aqueous thermodynamics of actinide species in natural waters is presented. This review includes a brief historical perspective on the application of Pitzer's equations to actinides, information on the difficulties and complexities of studying and modeling the different actinide oxidation states, and a discussion of the use of chemical analogs for different actinide oxidation states. Included are tables of Pitzer ion–interaction parameters and associated standard state equilibrium constants for each actinide oxidation state. These data allow the modeling of the aqueous thermodynamics of different actinide oxidation states to high ionic strength.     

Acid-base chemistry of red wine: analytical multi-technique characterisation and equilibrium-based chemical modelling

In this paper an attempt is made to model the alkalimetric titration trend (pH<7) of a series of red wines on the basis of an equilibrium-based calculation involving as input the chemical equilibria of the acid-base active substances, whose analytical concentration was determined in each wine under consideration. The chemical model (14 acid-base active substances and 22 protonation equilibria were considered) has been built in reliable conditions with respect to the chemical environment of the fluids under study, in order to describe the acid-base properties at a thermodynamic level using specific professional software. In this connection, protonation constant values of the substances involved were necessary, paying attention to: solvent composition, background salt, ionic strength and temperature. A series of synthetic solutions (based on mixed ethanol/water solvents at known ionic strength) was then pH-metrically titrated (25 °C) in order to refine suitable protonation constant values.Analytical measurements of carboxylic acids, amino acids, inorganic anions and metals were executed to know the concentration of a series of acid-base active reactants (pH<7) and the ionic strength state of each wine. Finally, a comparison between the experimental trend of the alkalimetric titration of each wine and the calculated one via the chemical model tested by means of a computer-assisted simulation has been performed. As an overall check of our job, the charge balance principle was adopted. During the alkalimetric titrations of each wine conductometric detection was performed as well, with the aim of confirming the values of ionic strength calculated using both analytical and equilibrium concentrations. The agreement we found when comparing the calculated values of ionic strength with varying pH with the trend of the conductometric signal can be considered as a significant validation of the chemical model proposed. The jump from the analytical to the equilibrium composition may allow the prediction of the effect on red wines consequent to chemical actions (addition of substances) or natural phenomena.     

介质对配合物稳定性的影响(Ⅴ)——Fe(tiron)——NaClO4-C2H5OH-H2O体系

用分光光度法于295±1K温度下测定了由高价阳离子Fe³⁺和高价阴离子tiron^4-(3,5-二磺酸基邻苯二酚)形成的配阴离子Fe(tiron)^-在乙醇-水混合溶剂中的稳定常数随离子强度的变化。分别用推广的Debye-Hückel方程和Pitzer方程计算了配阴离子的热力学稳定常数,发现对本体系De-bye-Hückel方程完全不能适用,而基于Pitzer方程的多项式逼近法则可得到满意的结果。讨论了介质效应和配合反应的标准迁移自由能。     

Effect of fuel choice on conductivity and morphological properties of samarium doped ceria electrolytes for IT-SOFC

The present investigation is emphasized on the effect of various combustion agents on the crystal properties, surface microstructure, and oxygen ion conductivity of 20% mole-Sm doped ceria (Ce_0.80Sm_0.20O_1.90/SDC20) ceramics as solid electrolyte for IT-SOFCs. The most widely used combustion agents for engineering ceramic production as ethylene glycol, diethylene glycol, triethylene glycol, L-alanine, L-valine, glycine, citric acid monohydrate, urea, and EDTA-citric acid were compared in terms of SDC20 properties. X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and electrochemical impedance spectroscopy (EIS) were used to determine the microstructure properties, crystal structure and ionic conductivity of SDC20 powder. XRD pattern of the ceramics revealed the formation of single-phase fluorite structure. According to the results of electrochemical analysis, the maximum total ionic conductivity was observed in SDC20 electrolyte synthesized using triethylene glycol as the fuel among all the synthesized electrolytes (5.72 x 10^–2 S.cm^–1).     

Environmental Coordination Chemistry: Binary Systems Comprising Some Bivalent Cations and Monocarboxylates in Aqueous Solution. Ionic Medium Effects on Equilibrium Constants

Abstract

The molar single activity coefficients associated with propionate ion (Pr) have been determined at 25°C and ionic strengths comprised between 0.300 and 3.00 M, adjusted with NaClO₄, as background electrolyte. The investigation was carried out potentiometrically by using a second class Hg/Hg₂Pr₂ electrode. It was found that the dependence of propionate activity coefficients as a function of ionic strength (I) can be assessed through the following empirical equation: log y_pr = –0.185 J^3/2 + 0.104 I². Next, simple equations relating stoichiometric protonation constants of several monocarboxylates and formation constants associated with 1:1 complexes involving some bivalent cations and selected monocarboxylates, in aqueous solution, at 25°C, as a function of ionic strength were derived, allowing the interconversion of parameters from one ionic strength to another, up to I = 3.00 M. In addition, thermodynamic formation constants as well as parameters associated with activity coefficients of the complex species in the equilibria are estimated. The body of results shows that the proposed calculation procedure is very consistent with critically selected experimental data.     

等压法测定298.15K下LiCl-CaCl2-H2O体系的活度系数

电解质水溶液热力学性质的研究一直是一个很活跃的研究领域.对含锂水盐体系热力学性质的研究不仅对电解质水溶液理论,而且对盐湖锂资源的开放利用都有非常重要的意义.姚燕等对ＬｉＣｌＫＣｌＨ2Ｏ[1],ＬｉＣｌＭｇＣｌ2Ｈ2Ｏ[2],ＬｉＣｌＭｇＳＯ4Ｈ2Ｏ[3,4],ＬｉＣｌＬｉ2ＳＯ4Ｈ2Ｏ[5]体系多温下热力学性质进行了研究,应用Ｐｉｔｚｅｒ电解质水溶液理论模型进行处理,计算出ＬｉＣｌ在不同体系中,很大的浓度范围内的活度系数.但在盐湖卤水中,ＣａＣｌ2的存在很普遍.对ＬｉＣｌＣａＣｌ2混合物在水溶液中的热力学性质研究对理解ＬｉＣｌ在盐…