Electrolytes, cadmium magnesium

This conversion is normally accompHshed by immersion, but spraying, swabbing, bmshing, and electrolytic methods are also employed (178) (see Metal SURFACE treatments). The metals that benefit from chromium surface conversion are aluminum, cadmium, copper, magnesium, silver, and 2inc. Zinc is the largest consumer of chromium conversion baths, and more formulations are developed for 2inc than for any other metal. 

The thermodynamic properties of magnesium make it a natural choice for use as an anode material in rechargeable batteries, as it may provide a considerably higher energy density than the commonly used lead-acid and nickel-cadmium systems, while in contrast to Pb and Cd, magnesium is inexpensive, environmentally friendly, and safe to handle. However, the development of Mg-ion batteries has so far been limited by the kinetics of Mg " " diffusion and the lack of suitable electrolytes. Actually, in spite of an expected general similarity between the processes of Li and Mg ion insertion into inorganic host materials, most of the compounds that exhibit fast and reversible Li ion insertion perform very poorly in Mg " ions. Hence, there... 

Reduction of add solutions of vanadium pentoxide to the tetravalent state also takes place with bismuth amalgam 5 magnesium gives the trivalent salts of vanadium, while by using zinc, zinc coated with cadmium, electrolytically deposited cadmium, or sodium amalgam in the absence of air, divalent vanadium salts are obtained in solution.7 Vanadous salts and hypovanadous salts are, however, much more conveniently prepared by electrolytic reduction of acid solutions of vanadium pentoxide in an atmosphere of carbon dioxide.8... 

Among the most stable cation radical salts are those of metallo-porphyrins. Most commonly the zinc, and magnesium metallo-porphyrins are used (M = Zn, Mg), but others, such as the cadmium porphyrin, are also used (Dolphin et al., 1973 Fajer et al., 1973 Dolphin and Felton, 1974). Tetraarylporphyrins [6, R = H Rj = aryl] or octaalkylporphyrins (R = alkyl, R = H) are the most common parent molecules. Recently, some zinc tetraalkylporphyrin cation radicals were also reported (Fajer et al., 1974). The metallo-porphyrins have low oxidation potentials (Fuhrhop and Mauzerall, 1969 Fuhrhop et al., 1973 Stanienda and Biebl, 1967), and their salts (e.g. perchlorates) can be made quite easily by anodic oxidation in the presence of an appropriate electrolyte. Chemical oxidation, by bromine or ferric ion for example, is also easily achieved, while... 

Another parameter which will have a very definite bearing on the choice of battery type is cell voltage, particularly on-load voltage, which are tabulated in Table 2.1 for various types of primary battery. It can be seen that these range from 0.75V/ceJI (mercury-cadmium) to over 3 V with some of the lithium and magnesium based organic electrolyte systems. 

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