Saturation, electrolyte

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

Depending on electrolyte saturation and KOH concentration, subsequent precipitation reactions may follow ... 

Carbon dioxide has been proposed as an additive to improve the performance of lithium batteries [60]. Aurbach et al. [61] studied the film formed on lithium in electrolytes saturated with C02, and using in situ FTIR found that Li2C03 is a major surface species. This means that the formation of a stable Li2C03 film on the lithium surface may improve cyclability [62], Osaka and co-workers [63] also studied the dependence of the lithium efficiency on the plating substrate in LiC104-PC. The addition of C02 resulted in an increase in the efficiency when the substrate was Ni or Ti, but no effect was observed with Ag or Cu substrates. 

After purging air out of the cell and the tubes with nitrogen, electrolyte saturated with nitrogen was introduced to the cell. 

FIGURE 14.6. Cyclic voltammetric curves for a AugiPtig/C catalyst (24 wt.%) on GC electrode (0.07 cm ) in 0.5M H2SO4 electrolytes saturated with O2 (solid curves) and Ar (dash curves). Scan rate 50 mV/s (from Ref. 35). 

When a sparingly soluble 1 1 electrolyte, saturated in the solution, is completely dissociated, the relation between the solubility product of the electrolyte (Ksp) and the conductivity of the solution (k) can be expressed, as a first approximation, by ... 

This system, commonly known as the mercury cell , is based on an amalgamated zinc anode, a concentrated aqueous potassium hydroxide electrolyte - saturated with zincate ion by zinc oxide - and a mercuric oxide/graphite cathode ... 

Voltammetric and coulometric measurements were conducted with the Pt electrode in the nonaqueous electrolyte saturated with CO2 (purity 99.99 %). The electrolyses were carried out in a closed electrolytic cell with CO2 saturated solution for 60 minutes. The current density was -5 mA/cm. The products were analyzed by gas chromatographs and a... 

Table 6 and the discussion above showed tliat Ni, Fe, Pt, and Ti electrodes, inert to CO2 reduction in aqueous media at 1 atm, yield products in nonaqueous electrolyte solution. HER and CO2 reduction proceed in parallel competitively in aqueous electrolytes saturated with CO2. Nonaqueous electrolyte solution does not contain water except small amount of residual one, and thus CO2 reduction will take place with HER severely suppressed. 

The voltage drop observed in 5.10, typically 0.02-0.03 V, at the beginning of discharge, is related to the delay of the anodic discharge reaction (see Sect. 5.3.2), due to the electrolyte saturation with lead ions. 

Sects. 4.1.2 and 4.2.1). In order to check the hypothesis of bubble formation, the authors of [122] immersed dry surfaces of the QCM of different roughness and hydrophobicity into electrolytes saturated by oxygen (or hydrogen). In all cases removing gases in situ by electrochemical reduction (or oxidation) did not result in changes of either the resonant frequency or the width of resonance. This led to a conclusion that even on freshly formed metal/aqueous solution contacts, the size and coverage of bubbles (if they exist) are so low that they could not influence the QCM response. 

Figure 2. Effect of oxygen in the photovoltaic response of the platinized Chi a electrode, (a) Electrolyte purged with argon gas, measurements made under a positive pressure of Ar (b) O, electrolyte saturated with oxygen (c) , oxygen removed by passage of argon gas through the electrolyte solution for 30 min. The ordinate units are given in 10 electrons per incident photon. The efficiency of the liquid junction cell was calculated by dividing the photovoltaic response (electrons sec ) by the incident photoresponse (photons sec ).

When leakage of chloride ion through the reference electrode into the test solution is not permissible (as in titrations involving Ag+), a mercury/mercurous-sulfate reference electrode may be used instead of calomel or silver-chloride electrodes. This consists of a mercury electrode in contact with a sulfate electrolyte saturated with excess mercurous sulfate ... 

Weston cadmium cell A standard cell that produces a constant e.m.f. of 1.0186 volts at 20°C. It consists of an H-shaped glass vessel containing a negative cadmium-mercury amalgam electrode in one leg and a positive mercury electrode in the other. The electrolyte - saturated cadmium sulfate solution - fills the horizontal bar of the vessel to connect the two electrodes. The e.m.f. of the cell varies very little with temperature, being given by the equation = 1.0186 - 0.000 037 (T - 293), where T is the thermodynamic temperature. 

When the plates start gassing, the electrolyte is pushed out of the plate pores and is readily absorbed into the pores of the separator, thus the latter is fully saturated. On switching off the current, the gas leaves the plate pores and electrolyte is re-absorbed in these pores from the separator. Thus, only the largest diameter pores in the AGM separator remain empty, while the plate pores are again filled with electrolyte. So the parameter electrolyte saturation holds mainly for the AGM separator. 

For AGM with high electrolyte saturation, a capillary pressure of 9 cm Hg (1.8 psi) is needed for the gas to flow through pores of 20 pm diameter and a higher pressure is required to displace the electrolyte from the smaller pores. 

Ocular iontophoresis was first investigated in 1908 by the German investigator Wirtz, who passed an electric current through electrolyte-saturated cotton sponges placed over the globe for the treatment of corneal ulcers, keratitis, and episcleritis. ... 

The oxygen electrode can be represented by platinized platinum immersed in an electrolyte saturated with oxygen. This electrode is particularly important to cor-... 

By varying the electrolyte composition in the left compartment, we can study the effect of adsorbed species on the rate of hydrogen permeation. Figure 11.31 shows the results of experiments carried out with thin iron sheets (0.2 to 2 mm) in different electrolytes saturated or not with H2S [13]. Hydrogen sulfide does not change the diffusion coefficient in the metal but it facilitates the hydrogen dissolution into iron. As a consequence, its presence in the solution increases the observed permeability. In equation (11.24), this translates into an inerease of Chj- The described effect of H2S... 

Since electrochemistry is generally more suited to aqueous media, while organic chemistry is usually favored by the use of an organic solvent, the concept of two-phase electrolysis can be attractive. The best-known example is the second version of the Monsanto process for adiponitrile [8,9], in which an emulsion of aqueous electrolyte and acrylonitrile was employed. The roles of the acrylonitrile phase are to maintain the aqueous electrolyte saturated with acrylonitrile, and to extract the adiponitrile back out of the aqueous electrolyte, thereby simplifying product isolation. The organic medium is separated from the aqueous electrolyte, while the reactant and product are separated by distillation. The combination... 

Other types of salt bridges consist of electrolyte-saturated linen wicks or bundles of camel s hair. These are useful when one wishes to minimize the trauma to delicate tissues which occurs with electrode contact. Occasionally linen membranes are used in half-cells to maintain the physical position of the reactants, especially in standard emf cell construction. 

Figure 17.9 Influence of electrolyte saturation on energy density and oxygen recombination of AGM batteries.

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