Thermodynamics of multicomponent electrolyte solutions: Aqueous mixtures of two salts from among NaCl,KCl, NaH2PO4, and KH2PO4 at 25° C

Five of the six possible aqueous two-salt mixtures from among NaCl, KCl, NaH₂PO₄,and KH₂PO₄ have been studied by the isopiestic method at 25°C. The sixth mixture, NaCl–KCl, has been studied previously. The deviations from ideal mixing behavior are described by a series of coefficients which were found by regression analysis. The coefficients were used to calculate the excess Gibbs energies of mixing for equal ionic strength fractions of each salt and the trace activity coefficient of each salt at an ionic strength of 2 mode-kg^–1. The cross-square mixing rule is obeyed within experimental uncertainty for the excess Gibbs energies of mixing.     

Pressure effect on grain boundary wetting at various temperatures

Bicrystals of Fe-6 at.% Si alloy containing <001> 5 tilt grain boundaries with a deposited zinc layer have been annealed at various hydrostatic pressure at four temperatures between 700° and 905°C. After the anneals the dihedral angle of the grain boundary groove formed at the site of the grain boundary intersection with the solid-melt interphase boundary has been measured. The transition from complete to incomplete wetting of the grain boundary by the zinc-rich melt (dewetting phase transition) has been found to occur as the pressure increased at all temperatures studied. The temperature dependence of the dewetting transition pressure p _w has been determined. That dependence has a minimum at a temperature of 790°C, which is close to the peritectic temperature in the Fe–Zn system (782°C). A thermodynamic analysis of the wetting phenomena in the two-component system, based on Becker's regular solution model for the surface tension of the interphase boundary, explains the minimum in the p _w (T) dependence.     

Energetics of magnesium, strontium, and barium doped lanthanum gallate perovskites

LaGaO₃ perovskites doped with Sr or Ba at the La site and Mg at the Ga site were prepared by solid-state reaction or sol-gel method and characterized. Enthalpies of formation from constituent oxides at 298 K were determined by high-temperature oxide melt solution calorimetry. Energetic trends are discussed in terms of defect chemistry. As oxygen deficiency increases, formation enthalpies define three trends, LaGa_1−yMg_yO_3−δ (LGM), La_1−xSr_xGa_1−yMg_yO_3−δ (LSGM), and La_1−xBa_xGa_1−yMg_yO_3−δ (LBGM). They become less exothermic with increasing doping, suggesting a dominant destabilization effect from oxygen vacancies. The endothermic enthalpy of vacancy formation is 275±37, 166±18 and 138±12 kJ/mol of V_O^·· for LGM, LBGM and LSGM, respectively. Tolerance factor and ion size mismatch also affect enthalpies. In terms of energetics, Sr is the best dopant for the La site and Mg for the Ga site, supporting earlier studies, including oxygen ion conductivity and computer modeling.     

Investigation of electrochemical reactions on copper electrode in Cu4RbCl3I2 solid electrolyte

Investigations are carried out by potentiostatic method. It is found that at potentials ϕ less than 100 mV, a reaction rate of copper deposition is limited by the formation and the three-dimensional growth of copper nuclei and the rate of copper dissolution is limited by a two-dimensional growth of holes in the metal. The rate of nucleus growth was evaluated at 10⁻⁹...10⁻⁶ μm s⁻¹ depending on the potential. At ϕ>120 mV, the reaction rate is limited by charge transport at the exchange current density of 2.7 mA cm⁻² and the anodic transfer coefficient α_a≈ 0.45. The accumulation of a divalent copper phase on Cu/Cu₄RbCl₃I₂ interface at anodic polarization is explained by a parallel course of Cu⁺ − e → Cu²⁺ reaction.     

Multicomponent electrolyte systems: Dependence of ionic mobilities on aqueous organic solvent structure

Ionic mobility data for multicomponent electrolyte systems at low concentrations are scarce due to experimental difficulties and are actually restricted to aqueous solutions of alkali chlorides. Some new results are presented which have been obtained by using a radiotracer method valid even if one of the ionic species is present at very low concentrations (tracer ion). The following electrolyte systems (two electrolytes with a common ion in a solvent) have been investigated at a 0.5N total ionic strength: NaNO₃–AgNO₃, KNO₃–AgNO₃, LiNO₃–AgNO₃ either in pure water or in water-rich (acetonitrile or dimethylsulfoxide) mixed solvents. Since ionic conductivity data processing by an extended law generalized to mixtures, such as that proposed by Quint and Viallard, has proved to be delicate to handle, our experimental results have been compared with the qualitative predictions of the classical Onsager-Fuoss limiting law. The main conclusion of this work is to give clear experimental evidence of the inability of any continuum theory to predict the ionic mobilities when solvent structural effect have to be taken into account. Consequently, the ionic behavior, particularly that of the Ag⁺ ion, has been interpreted in terms of preferential solvation and solvent microscopic structure. The trace mobility measurements reflect the maximum structural effect on the ionic transport properties.     

多相高分子快离子导体阻抗谱的研究

研究了以ＬｉＣｌＯ４掺杂的聚乙二醇聚氨酯双离子导体及磺酸型聚乙二醇聚氨酯离聚物单一离子导体的阻抗谱，给出了多相快离子导体交流阻抗测试系统的等效电路．通过阻抗谱计算机解析，计算得出了样品的基本电学参数．通过讨论界面阻抗的色散现象，计算出样品的离子电导率，和阻抗谱解析法得到的结果相一致．     

Electrochemical Processes of Sulfide in NaCl Electrolyte Solutions on Mercury Electrode

The electrochemical processes of sulfide in NaCl electrolyte solutions were studied using stripping cyclic voltammetry, differential capacity and chronoamperometric measurements. Some new effects were observed and are here discussed. At potentials around ?0.1 to ?0.3 V a pair of Faradaic adsorptive peaks, which can only be observed in the presence of chloride, is attributed to the formation of HgCl ion from the deposited layer of HgS. A second pair of peaks of purely capacitive character was observed at ?0.4 V. This is the result of the reorientation and partial desorption or transformation of HgS layers. The formation and dissolution of HgS layers on mercury has been well investigated previously. We observed some new effects after depositing approximately ten layers of HgS and attributed this to the formation of polysulfides at positive potentials.     

聚合物固体电解质基体的研究进展

综述了聚合物固体电解质基体的设计原理、分类和研究进展，并对今后在聚合物基体设计方面的研究前景作了展望。     

New Type High Efficient Quasi-Solid-State Ionic Liquid Electrolyte for Dye-Sensitized Solar Cells

For the fist time the preparation of a mostly solid-state high efficiem electro-conductive material comprising 1-methyl-3-propylimidazolium iodide （MPII）, benzimidazole （BI）, iodine and lithium iodide was reported. In this electrolyte, BI acts as not only additives but also gelators. With its significant electrochemical properties, an overall efficiency of 3.07% was achieved under AM 1.5 （100 mW/cm^2）.     

An NMR study of methanol diffusion in polymer electrolyte fuel cell membranes

Methanol diffusion in two polymer electrolyte membranes, Nafion 117 and BPSH 40 (a 40% disulfonated wholly aromatic polyarylene ether sulfone), was measured using a modified pulsed field gradient NMR method. This method allowed for the diffusion coefficient of methanol within the membrane to be determined while immersed in a methanol solution of known concentration. A second set of gradient pulses suppressed the signal from the solvent in solution, thus allowing the methanol within the membrane to be monitored unambiguously. Over a methanol concentration range of 0.5–8 M, methanol diffusion coefficients in Nafion 117 were found to increase from 2.9 × 10⁻⁶ to 4.0 × 10⁻⁶ cm² s⁻¹. For BPSH 40, the diffusion coefficient dropped significantly over the same concentration range, from 7.7 × 10⁻⁶ to 2.5 × 10⁻⁶cm² s⁻¹. The difference in diffusion behavior is largely related to the amount of solvent sorbed by the membranes. Increasing the methanol concentration results in an increase in solvent uptake for Nafion 117, while BPSH 40 actually excludes the solvent at higher concentrations. In contrast, diffusion of methanol measured via permeability measurements (assuming a partition coefficient of 1) was lower (1.3 × 10⁻⁶ and 6.4 × 10⁻⁷ cm² s⁻¹ for Nafion 117 and BPSH 40 respectively) and showed no concentration dependence. The differences observed between the two techniques are related to the length scale over which diffusion is monitored and the partition coefficient, or solubility, of methanol in the membranes as a function of concentration. For the permeability measurements, this length is equal to the thickness of the membrane (178 and 132 μm for Nafion 117 and BPSH 40 respectively) whereas the NMR method observes diffusion over a length of approximately 4–8 μm. Regardless of the measurement technique, BPSH 40 is a greater barrier to methanol permeability at high methanol concentrations.