Electrolyte selection

Similarly, concepts of solvation must be employed in the measurement of equilibrium quantities to explain some anomalies, primarily the salting-out effect. Addition of an electrolyte to an aqueous solution of a non-electrolyte results in transfer of part of the water to the hydration sheath of the ion, decreasing the amount of free solvent, and the solubility of the nonelectrolyte decreases. This effect depends, however, on the electrolyte selected. In addition, the activity coefficient values (obtained, for example, by measuring the freezing point) can indicate the magnitude of hydration numbers. Exchange of the open structure of pure water for the more compact structure of the hydration sheath is the cause of lower compressibility of the electrolyte solution compared to pure water and of lower apparent volumes of the ions in solution in comparison with their effective volumes in the crystals. Again, this method yields the overall hydration number. 

The effect of the YSZ coating on the ceria-based solid electrolyte was shown in Table 1. When the YSZ I SDC membrane was used as the solid electrolyte, selectivities to acrylaldehyde (Scho) carbon monoxide (Sco) and carbon dioxide (Scoa) based on converted propene was 13.4%, 25.6% and 61%, respectively. Here, it should be emphasized that the selectivity to acrylaldehyde increased with YSZ coating compared with that (Scho =8.5 %) obtedned by using SDC alone as a solid electrolyte. In addition, it was found that carbon monoxide formation was observed in the present study, although its formation was not detected in the case of SDC alone. The same phenomena were observed, when the Gd doped... 

Potentiometric Results. As shown earlier, a single salt concentration variation has no effect on the interfacial potential. Thus, to study the effect of the dye cation on the interfacial potential, other ions must be present. Supporting electrolytes, selected in such a way that an ideally polarizable interface is formed when the dye is absent, are conveniently used. 

Much research is underway on rechargeable lithium batteries. These systems hold out the promise of an environmentally benign system, especially the newer "lithium ion" systems, depending on the cathode and electrolyte selected. If any of these efforts are successful, the rechargeable lithium ion battery, which utilizes a carbonaceous material as the anode, could eventually replace the Ni/Cd and Ni/metal hydride systems. 

The electrolyte type (acidic, neutral, or basic) should be selected, so that the semiconductor of interest does not corrode when immersed in the solution. Some general guidance in electrolyte selection can be obtained from Pourbaix diagrams. As an example, the Pourbaix diagram of WO3 is presented in Fig. 3.8. 

WO3 is stable below pH = 2 and at anodic potentials, and thus acidic electrolytes are often used. However, defining general electrolyte selection rules is a difficult task, since physical and chemical properties of semiconductor materials may vary depending on different deposition techniques. Some examples of... 

The standard procedure for stability testing utilizes the 2-electrode short-circuit measurement detailed in Chapter 2-Electrode Short Circuit and j-v . See Section Cell Setup and Connections for 3- and 2- Electrode Configurations for a discussion on basic cell setup and electrolyte selection. 

The problems of electrolyte selection have become particularly acute in connection with the miniaturization and sealing of a variety of electrochemical devices such as batteries, sensors, and the like. Apart from all their advantages, aqueous electrolyte solutions here exhibit certain defects, insofar as sealing of a device containing them is often difficult, and leaking of the liquid readily occurs (particularly when alkaline solutions are used). From devices that are not sealed, the electrolyte solvent... 

Simple ions and molecule dispersants are most mainly used in aqueous suspensions. They are inorganic compounds, including salts, acids, and bases, which are also known as electrolytes. Selective adsorption of one type of ions onto the particle surface coupled with the formation of a diffuse layer of the counterions, i.e., ions with opposite charge, provides electrostatic stabilization, due to the repulsion between the double layers. The stability of the suspensions is influenced through control the repulsion force between the particles, by the valence and radius of the counterions. According to the Schulze-Hardy mle, the higher the valence of the counterions, the more effective they will be, while for ions with the same valence, the smaller the ions the more effective the dispersants are. 

The electrolyte selected for a given application must be compatible with the electrodes in more than one way. Firstly, electrolytes that corrode the electrode surface are clearly undesirable. Lithium is a curiously reactive electrode material, susceptible to attack not only from moisture but also by certain polymer electrolytes. Secondly, as explained in section 1.1.1, the electrolyte must be sufficiently deformable to maintain contact with cathode particles even when they are substantially expanded or contracted at different stages of the charge-discharge cycle. Thirdly, as mentioned in the previous section, adherence of the electrolyte to the electrodes must be consistently maintained if direct electrode-electrode shorting is to be avoided, and this is easier to achieve with composite, semi-crystalline or highly viscous materials. 

Diamond, J.M., Wright, E.M. Biological membranes the physical basis of ion and non-electrolyte selectivity. Annu. Rev. Physiol. 31, 581-646... 

The slip dissolution model assumes that plastic deformation at the crack tip is responsible for the activation. But other mechanisms can have the same effect. Tensile stress at the crack tip could, for example, break a brittle tarnish film or passive oxide film, thereby exposing the base metal to the electrolyte. Selective dissolution of alloy components at the crack tip could locally weaken the metal matrix and thus permit... 

Electrolyte selection is very similar to what is described for the 3-electrode cell. Since the catalyst layer is separated from the aqueous electrolyte solution by a permselective ionomer membrane, only water and protons can transport through the membrane to reach the catalyst layer. This helps minimize or eliminate the adverse impact of anion adsorption (onto the catalyst surface) on the reaction kinetics. 

In a series of papers by Kirchheim ef al. [180,196,197], fhe dissolution rates of Fe and Cr in Fe-Cr alloys were investigated wifhin fheir passive range in H2SO4 solution. Time-resolved chemical analysis of fhe solution was performed by atomic absorption spectroscopy of samples of electrolyte. Selective dissolution of iron during the transient passivation stages was exploited in terms of Cr enrichmenf in fhe passive layer, and once the steady state was reached, simultaneous dissolution was accurately verified. 

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