Barium plumbate

One conductive additive which is relatively stable is barium plumbate (BaPbOs) [11]. This is a ceramic [12] with the perovskite structure and is easily made by standard ceramic-powder technology. Addition of this material to positive plates in a lead-acid battery significantly improves the formation efficiency. The formation mechanism is changed when the conductive particles are dispersed in the plate. Formation not only proceeds from the grid towards the centre of the pellet, but also takes place slowly around the conductive particles in the plate. The conductive paths of Pb02 grow and make connection with each other during formation to establish a network, which further facilitates the formation. 

The formation mechanisms for plates with and without BaPbOs appear to be different. As shown in Fig. 4.2, the formation of a plate without the conductive additive proceeds from the grid towards the centre of the pellet (Fig. 4.2(a) to (d)) this is consistent with the results of other studies [10]. When the conductive particles are dispersed in the plate (Fig. 4.2(e)), long-range conductive paths are apparently 

The effect of loading of BaPb03 in a positive plate on the formation efficiency is summarized in Table 4.4. The data show that significant improvement in formation starts at a loading level as low as 0.5wt.%. This formation enhancement increases with BaPb03 loading and approaches a plateau. Beyond about 7wt.%, additional BaPb03 has no influence on the formation efficiency. 

Once the battery is formed, a stable conductive additive can enhance the current-acceptance of deeply discharged batteries. This has been demonstrated [12] by the addition of lOwt.% BaPbOs to a conventional positive plate made by adding 

325 rel. dens. H2SO4 to a water-based, ball-mill, leady oxide and O.lwt.% polyester fibres. The plates were prepared via a standard process for commercial automotive batteries and used to construct flooded test cells with one positive and two negative plates. The cells were first given two cold-cranking tests alternately with three reserve-capacity tests. Then, the cells were discharged over 20 h to 1.5 V, discharged on a 2-Q resistive load for five days, and finally left on open-circuit at 

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Investigations by Zintl and Ranch, suggested that, in aqueous alkali, the oxyanions of lead (plumbate and plumbite) do not exchange at room temperature. This has been confirmed by Fava, who detected no exchange in 7 M KOH over a period of ten days at room temperature, but found measurable exchange at temperatures in the range 57 to 100 °C with reactant concentrations 2x 10 M. The barium plumbate separation method was used with the tracer Ra D. 

Barium plumbate is a relatively stable conductive ceramic having the perovskite structure. Addition of this material to PAM [29-31] improves significantly the formation efficiency. 

Table 4.3. Effect of barium plumbate on positive-plate formation [11] (reproduced by...

Barium plumbate is electrochemically stable in the positive plate. Chemically, however, it can be slowly attacked by dilute sulfuric acid. The first-order rate constant for decomposition of barium plumbate in dilute sulfuric acid was determined to be A = 2.6 x 10 " H exp (-EJRT), where is 31.6 kcal, R is the gas constant, and T is the absolute temperature. The half-life of this material in... 

Barium plumbate is a relatively stable conductive ceramic having the perovskite structure. Addition of this material to PAM improves significantly the formation efficiency [9,10]. Lead dioxide or red lead (25—50%) are widely used by many major battery manufacturers. When H2SO4 is added to red lead the following reaction proceeds ... 

Although a higher temperature is required for the preparation of oxygen by this method than is the ease with barium peroxide (set p. 10), the calcium plumbate is more rapidly regenerated in the presence of air when the temperature is lowered furthermore, il is not necessary to remove the carbon dioxide from the air as in Brin s process. 

Barium sulfate Calcium plumbate Cobalt sulfate (ous) Lead Lead oxide, black Lead sulfate Lithium Nickel oxide (ic) batteries, storage/dry cell Zinc... 

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