Electrolyte temperature range

Cells are generally operated using 1.5—6 wt % AI2O2 in the electrolyte. Saturation ranges between 6—12% AI2O2 depending upon composition and temperature. 

Solid oxide fuel cells consist of solid electrolytes held between metallic or oxide elecU odes. The most successful fuel cell utilizing an oxide electrolyte to date employs Zr02 containing a few mole per cent of yttrium oxide, which operates in tire temperature range 1100-1300 K. Other electrolytes based... 

Figure 28 shows the discharge characteristics at a current density of 1.2 mA cm-2 of electrolytic MnOz heat-treated at various temperatures. From the characteristics shown, it may be concluded that the optimum heat-treatment temperature range for stable discharge is between 375 and 400 °C, which agrees with the data of Fig. 27. 

Viscosities and specific weights of complexes and the corresponding aqueous phases, with the aim of simulating realistic battery conditions with MEP MEM ratio of 1 1, 3 1 and 6 1 in the electrolyte at 50, 75 and 100% states of charge, were studied in a temperature range between 10 and 50 °C [83], Kinematic viscosities between 5 10 6 and 30 -10 6 m2s of the complex phases were found. MEP-rich ones. 

A series of experiments have been undertaken to evaluate the relevant thermodynamic properties of a number of binary lithium alloy systems. The early work was directed towards determination of their behavior at about 400 °C because of interest in their potential use as components in molten salt batteries operating in that general temperature range. Data for a number of binary lithium alloy systems at about 400 °C are presented in Table 1. These were mostly obtained by the use of an experimental arrangement employing the LiCl-KCl eutectic molten salt as a lithiumconducting electrolyte. 

The search for a suitable electrolyte requires comprehensive studies. It is necessary to measure the conductivities of electrolytes with various solvents, solvent mixtures, and anions over the accessible concentration range of the salts, and to cover a sufficiently large temperature range and the whole composition range of the binary (or ternary) solvent mixture. Figure 11 shows, as an example, the conductivity plot of LiAsF6/GBL as a function of temperature and molality. 

Furthermore a good electrolyte stability and temperature stability are necessary, and they must not show phase inversion over the temperature range which exists in the reservoir because of the increase in viscosity. 

There is a wide variety of solid electrolytes and, depending on their composition, these anionic, cationic or mixed conducting materials exhibit substantial ionic conductivity at temperatures between 25 and 1000°C. Within this very broad temperature range, which covers practically all heterogeneous catalytic reactions, solid electrolytes can be used to induce the NEMCA effect and thus activate heterogeneous catalytic reactions. As will become apparent throughout this book they behave, under the influence of the applied potential, as active catalyst supports by becoming reversible in situ promoter donors or poison acceptors for the catalytically active metal surface. 

There are a whole variety of types of fuel cell, named after the electrolyte used, each operating at a preferred temperature range with its own feedstock purity criteria (Table 6.3). 

The possibility of measuring the Volta potential in the system metal-solid-state electrolyte and using the data obtained to determine ionic components of the free lattice energy has been shown in our papers. Earlier, Copeland and Seifert measured the Volta potential between Ag and solid AgNOj in the temperature range between 190 and 280 °C. They investigated the potential jump during the phase transition from solid to liquid salt. 

To extend the electrolytic conductivity reference database considerably above 1200 K, Cap2 has also been adopted as a standard by them, with extension of the temperature range for the electrolytic conductivities of KNO3 and NaCl. Their provisional recommendations as of 1991 are given in Table 3. New data recommended for molten alkah chlorides will be discussed in Section VI. 

Electrolytic zinc smelters contain up to several hundred cells. A portion of the electrical energy is converted into heat, which increases the temperature of the electrolyte. Electrolytic cells operate at temperature ranges from 30 to 35°C (86 to 95°F) at atmospheric pressure. During electrowinning a portion of the electrolyte passes through cooling towers to decrease its temperature and to evaporate the water it collects during the process. 

Salt bath descaling is the process of removing surface oxides or scale from a workpiece by immersion of the workpiece in a molten salt bath or a hot salt solution. The workpiece is immersed in the molten salt [temperatures range from 400°C to 540°C (750-1000°F)], quenched with water, and then dipped in acid. Oxidizing, reducing, and electrolytic baths are available, and the particular type needed depends on the oxide to be removed. 

In virtually all of the simple immersion and two electrode experiments carried out so far, in-diffused H has been detected at the 1016/cm3 level or less. There has been no demonstration that large densities (> 1018/cm3) of defects can be passivated by these methods, and where plasma and electrochemical treatments have been directly compared, the former have been found to be more effective (Tavendale et al., 1986). In contrast to plasma techniques, the electrolyte boiling point limits the temperature range of electrochemical methods, although several hundred degrees Celsius can be utilized for electrolytes like H3P04. 

It was mentioned previously that the narrow range of concentrations in which sudden changes are produced in the physicochemical properties in solutions of surfactants is known as critical micelle concentration. To determine the value of this parameter the change in one of these properties can be used so normally electrical conductivity, surface tension, or refraction index can be measured. Numerous cmc values have been published, most of them for surfactants that contain hydrocarbon chains of between 10 and 16 carbon atoms [1, 3, 7], The value of the cmc depends on several factors such as the length of the surfactant chain, the presence of electrolytes, temperature, and pressure [7, 14], Some of these values of cmc are shown in Table 2. 

Similarly if this electrolyte is made into a composite with SrS, SrC2 or SrH2, the system may be used to measure sulphur, carbon and hydrogen potentials respectively, the latter two over a restricted temperature range where the carbide or hydride are stable. The advantage of these systems over the oxide electrolytes is that the conductivity of the fluoride, which conducts by F ion migration, is considerably higher. 

Activation Energy (Ea) and Conductivity (o) Values at High- and Low-Temperature Range for Some Zirconia-Based Electrolytes [10]... 

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