Solid electrolyte thermodynamic properties

In the early part of this century, many types of solid electrolyte had already been reported. High conductivity was found in a number of metal halides. One of the first applications of solid electrolytes was to measure the thermodynamic properties of solid compounds at high temperatures. Katayama (1908) and Kiukkola and Wagner (1957) made extensive measurements of free enthalpy changes of chemical reactions at higher temperatures. Similar potentiometric measurements of solid electrolyte cells are still made in the context of electrochemical sensors which are one of the most important technical applications for solid electrolytes. 

Fei O, called wiistite, has been studied from the viewpoints of thermodynamics and physicochemical properties. As mentioned in Section 1.1, stoichiometric FeO cannot be prepared under the usual conditions. Many investigators have studied the thermodynamic properties of wustite by use of various kinds of techniques. Here we introduce a study carried out by Fender and Rileywho used a solid electrolyte cell (see Section 1.4.8) to determine the equilibrium oxygen pressure Por The following cell was utilized,... 

As already mentioned, salt-containing liquid solvents are typically used as electrolytes. The most prominent example is LiPF6 as a conductive salt, dissolved in a 1 1 mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) as 1 molar solution. It should be mentioned that this electrolyte is not thermodynamically stable in contact with lithium or, for example, LiC6. Its success comes from the fact that it forms an extremely stable passivation layer on top of the electrode, the so-called solid-electrolyte interface (SEI) [35], Key properties of such SEI layers are high Li+ and very low e conductivity - that is, they act as additional electrolyte films, where the electrode potential drops to a level the liquid electrolyte can withstand [36],... 

The electrolytic permeability is a property of any solid electrolyte, since a local equilibrium involving ions and electrons is required by - thermodynamics for any conditions close to steady-state or global equilibrium. However, it is possible to optimize the level of permeability, depending on particular applications. In many cases, the permeability is a parasitic phenomenon leading to power losses in - fuel cells and - batteries, lower efficiency of solid-state electrolyzers and -> electrochemi-... 

The optical, electrical, and thermodynamic properties of tellurium subhalides have attracted considerable research interest. For instance, a-Tel has been suggested to find applications as solid electrolytes in galvanic cells. 

Expressions obtained for the free energy, pressure and chemical potentials can be used to study the thermodynamic properties of the electrolyte solutions, in particular, to describe the phase diagram of ionic fluids. Such a possibility is illustrated in Fig. 7, which shows the effect of ion pairing on liquid-liquid coexistence curve in the ion-dipole model as a function of the ion concentration a = ()%/(pi + ps) and reduced temperature T = (Ms)-1/2, bs = Rpl/Rl The solid line corresponds to the ion-dipole model with the parameter of ion association, B = 10. The dashed line corresponds to the ion-dipole... 

Five samples of the YSZ with different concentrations of iron, impregnated into the electrolyte, have been studied. For investigation of the influence of the iron admixture on the electrophysical properties of the solid electrolyte, four samples from five were saturated by a FeCl solution of different concentrations (1, 3.8, 7.5, and 15%), followed by the annealing of all samples at 1600°C for 3 hours. The fifth sample had the minimum iron admixture (0.001%). After annealing, all samples had a density of 5.4 g/cm with zero open porosity. Figure 1.17 shows experimental emf measurements for all samples of the prepared electrolyte. The thermodynamical emf (J = 1) corresponding to Equation (1.22) is shown as well. The results of the experimental measurements in this figure clearly show that the more iron admixture... 

Electrochemical processes occur in batteries, fuel cells, electrolysis, electrolytic plating, and corrosion (generally an undesirable process). Electrochemical processes can be used to produce electricity, to recover metals from solution, and for the measurement of the thermodynamic properties of electrolyte solutions. The device used to study electrochemical reactions is an electrochemical cell, which consists of two electrodes (metallic conductors) in electrolytes that are usually liquids containing salts, but may be solids, as in solid-state batteries. The two electrodes may be in the same electrolyte, as shown in Fig. 14.6-la, or each electrode may be in a separate compartment wiffi its... 

A closed system solid electrolyte electrochemical cell has been designed to investigate the thermodynamic properties of metal oxides. This technique gave a rapid cell response and highly stable potentials through the elimination of mixed potentials. The... 

GEE/SHE] Gee, R., Shelton, R. A. J., Thermodynamic properties of Cr, Mn, Co and Ni dichlorides from emf measurements on cells with solid electrolytes, Trans.-Inst. Min. Metall. Sect. C, 85, (1976), C208-C210. Cited on pages 127, 376. 

Aqueous Solvation.—A review, covering the 1968—1972 publications, deals with physical properties, thermodynamics, and structures of non-aqueous and aqueous-non-aqueous solutions of electrolytes, and complete hydration limits. Thermodynamic aspects of ionic hydration also reviewed include the thermodynamic theory of solvation the molecular interpretation of ionic hydration hydration of gaseous ions (AG s, H s, and AA s) thermodynamic properties of ions at infinite dilution in water, solvent isotope effect in hydration reference solvents and ionic hydration and excess properties. A third review on the hydration of ions emphasizes the structure of water in the gaseous, liquid, and solid states the size of ions and the hydration numbers of ions and the structure of the hydrated shell from measurements of mobility, compressibility, activity, and from n.m.r. spectra. Pure water and aqueous LiCl at concentrations up to saturation have been examined by neutron and X-ray diffraction. For the neutron studies LiCl and D2O are employed. The data are consistent with a simple model involving only... 

We studied the thermodynamic properties of aluminum antimonide and the AlSb - GaSb system by the emf method, using a solid electrolyte. 

LSE, the classical electrochemistry, is concerned with electrochemical cells (ECs) based on liquid ionic-conductors (liquid electrolytes (LEs)). Solid-state electrochemistry is concerned with ECs in which the ionic conductor (electrolyte) is a solid. Both fields are based on common thermodynamic principles. Yet, the finer characteristics of ECs in the two fields are different because of differences in the materials properties, conduction mechanisms, morphology and cell geometry. Differences that come immediately to mind are (1) The lack of electronic (electron/hole) conduction in most LEs, while electronic conduction exists to some extent in all solid electrolytes (SEs). (2) In LEs both cations and anions are mobile, while in SEs only one kind of ions is usually mobile while the other forms a rigid sublattice serving as a frame for the motion of the mobile ion. An... 

Although one of the more complex electrochemical techniques [1], cyclic voltammetry is very frequently used because it offers a wealth of experimental information and insights into both the kinetic and thermodynamic details of many chemical systems [2], Excellent review articles [3] and textbooks partially [4] or entirely [2, 5] dedicated to the fundamental aspects and apphcations of cyclic voltammetry have appeared. Because of significant advances in the theoretical understanding of the technique today, even complex chemical systems such as electrodes modified with film or particulate deposits may be studied quantitatively by cyclic voltammetry. In early electrochemical work, measurements were usually undertaken under equilibrium conditions (potentiometry) [6] where extremely accurate measurements of thermodynamic properties are possible. However, it was soon realised that the time dependence of signals can provide useful kinetic data [7]. Many early voltammet-ric studies were conducted on solid electrodes made from metals such as gold or platinum. However, the complexity of the chemical processes at the interface between solid metals and aqueous electrolytes inhibited the rapid development of novel transient methods. 

The calculations can easily be modified for other electrolytes. A further conclusion can be drawn from eq. (9-13) If the transport properties of the solid electrolyte and the thermodynamic parameters of the reference electrode are known, then the thermodynamic quantities AG, ai, and Pi can be measured. On the other hand, if the thermodynamics of both electrode systems are known, then the transport properties of the electrolyte can be studied. For example, by a simple rearrangement of eq. (9-13) it follows that ... 

Probes using solid electrolytes have been used in various investigations of thermodynamic properties but have not been yet followed by commercialisation (25). Most spectacular of these is the report (26) that A1 N is a conductor presumably for triply charged nitrogen. 

The fist of publications [1-50] covers the period from 1958 to 1990, i.e., up to the very last years of the united Soviet Union. It includes only a small part of the publications and stiU reflects the wide variety of research on solid electrolytes at the IE US AS/IE UD AS and the journals publishing these results. There were many theoretical and experimental studies on electrochemical cells with solid electrolytes [1, 4, 5, 21, 39] and an extensive research on the phase composition of oxide ionic conductors [2] and their electric properties [3, 6, 8, 10, 13, 14, 17, 18, 20, 30, 34, 48]. Many papers were related to practical applications like sohd electrolyte degradation [33, 47] or application limits related to the electronic conductivity of the solid electrolytes [5, 30, 40, 43]. There were many publications on the implementation of different electrodes and on the kinetics of electrode processes [23,27, 31, 35, 36, 45], on investigations of the electrode overvoltage [7, 12, 25, 28], on impedance spectroscopy of solid electrolytes [19, 27], and on isotope exchange research [15,16]. The double layer and electrocapUlarity of solid electrolytes were studied in detail [9, 11, 19, 32, 44]. Systematic studies were performed on the thermo-EMF of different solid electrolytes [22,24,29], the EMF of electrochemical cells with solid electrolytes [26, 39], and the thermodynamics of oxygen in molten copper [41]. Applied research was focused on electrochemical oxygen pumps... 

As for thermodynamic measurements using liquid electrolytes, galvanic cells with solid ion conductors are widely applied to study thermodynamic properties of solids and melts. These measurements are based on the determination of galvanic cell emf (Chap. 1) when the reference electrode potential is known. In a simplest case, when A " cation-conducting electrolyte is employed and the RE comprises metal A, the cells... 

Precise control and monitoring of the oxygen pressure in the experimental chamber is required for the determination of thermodynamic and transport properties in MIECs. Electrochemical devices have been developed since more than thirty years, allowing the control of the oxygen pressure in the 1 - 10-27 p,aj. range in various gas mixtures or under partial vacuum. Solid electrolyte micropjrobes have also been proposed for the local determination of the oxygen activity on the surface of a non-stoichiometric oxide. 

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