Capacity lead oxides

The production of tubular positive plates is in principle similar to that of pasted plates. A number of manufacturers use the same gray oxide as the basic filling substance. Sometimes the share or red lead or minium (Pb304) is increased above 25 or even to 100wt.%. The latter is more economic when the manufacturer runs his own minium plant then the expense of the chemical oxidation of lead oxide (PbO) to minium (Pb304) may be compensated by reduced formation cost. Furthermore, curing is not required, because of the high oxidation state, and the battery starts with full capacity when formed. 

Several single and binary oxides have a capacity to oxidize propene to dimerization products. The first compound formed is 1,5-hexadiene, which may undergo further dehydrogenation and cyclization leading to benzene. 

Nutritional status Many antioxidants are present in the diet (e.g., vitamin E, vitamin C, peptides for the synthesis of glutathione, trace metals, and minerals like zinc). However, poor nutrition or malabsorption leads to deficiency of these key vitamins and antioxidants. This may impair the antioxidative defense capacity, leading to drug-induced oxidative stress and lower threshold for DILL In a preclinical study, a mere 1.6- and 2.1-fold increase in liver zinc content was associated with an increase in liver metallothionein between 50- and 200-fold.38 Metallothionein is a key antioxidant protein in vivo capable of scavenging most common kinds of oxidative species.39 It is therefore conceivable that a lack of sufficient dietary available zinc could compromise a patient s hepatic metallothionein levels and his or her antioxidant reserve capabilities in liver. 

The heat capacity of solid lead oxide, PbO, is given by ... 

Alteration of the capacity of positive plates, prepared with different lead oxide powders, during the... 

The results of both studies [26] and [27] evidence higher capacity values for the cells with chemically synthesised PbO, which change but slightly on cycling. There seems to be some kind of genetic code in the lead oxide that exerts an influence on the end product. 

The above investigations indicate that the physical and chemical properties of the lead oxide used as precursor material for the production of battery plates, though the lead oxide is only a starting compound for a number of chemical processes (paste preparation and plate formation, whereby Pb02 and Pb are formed), exert an influence on the energetic and capacity performance parameters of lead-acid cells and batteries. Hence, it is essential to produce leady oxides with optimum and stable physico-chemical properties which would guarantee high battery performance. 

The active mass obtained from pastes containing no H2SO4 (0%) has very low capacity, irrespective of the temperature of paste preparation. That is why battery manufacturers use basic lead sulfate pastes, and not lead oxide ones, for the production of positive plates. 

SLI plates were kept in contact with air for different periods of time. The obtained kinetic curves of oxidation of the plates by the air are presented in Fig. 13.6. After reaching a definite critical temperature and moisture content, a vigorous oxidation or burning of the plates commences. This phenomenon is quite similar to the processes observed during curing of the pasted plates. At the end of this period of rapid oxidation, the active mass contains 50—60% sponge lead and up to 40—50% lead oxide and lead sulfate. This composition of the negative active mass yields only a very low capacity, and often none at all. 

However the battery structure has changed substantially from initial ones. In the early days of lead acid batteries, the corrosion layers formed on the surface of lead sheet were used as active materials. But at present, the pasted type electrodes, which are made from lead-oxide paste and lead-alloy grid, are used generally. Then such pasted type electrodes are charged in sulfuric acid to make positive and negative plates and have much larger effective surface area which leads to larger capacity compared to the batteries of the early days. 

In order to illustrate a useful approximation we shall assume that the heat capacities of the lead compounds are not available and instead apply Kopp s rule. This states that the molar beat capacity of a solid compound is the sum of the atomic heats of its component elements (6.4 cal mol for most elements). With this approximation the heat capacities of the lead oxide and the lead sulphide clearly cancel. 

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