Lead-acid batteries components

Tetrabasic Lead Sulfate. Tetrabasic lead sulfate [12065-90-6] 4PbO PbSO, mol wt 1196.12, sp gr 8.15, is made by fusion of stoichiometric quantities of Htharge (PbO) and lead sulfate (PbSO heat of formation, Ai/ = — 1814 kJ/mol (—434.1 kcal/mol). Alternatively, tetrabasic lead sulfate may be prepared by boiling the components in aqueous suspensions. At about 70°C, tribasic hydrate reacts with lead oxide to form tetrabasic sulfate. At 80°C, this transformation is complete in - 20 hours. Tetrabasic lead sulfate is used in limited quantities in Europe as a PVC stabilizer. However, in the United States, lead-acid batteries have been developed by BeU Telephone Laboratories, which contain tetrabasic lead sulfate. Such batteries are used for emergency power at telephone switchboard stations and have an anticipated service life of over 50 years. 

In Figure 1, the cutaway view of the automotive battery shows the components used in its constmction. An industrial motive power battery, shown in Figure 2 (2), is the type used for lift tmcks, trains, and mine haulage. Both types of batteries have the standard free electrolyte systems and operate only in the vertical position. Although a tubular positive lead—acid battery is shown for industrial appHcations, the dat plate battery constmction (Fig. 1) is also used in a comparable size. 

The lead—acid battery is comprised of three primary components the element, the container, and the electrolyte. The element consists of positive and negative plates connected in parallel and electrically insulating separators between them. The container is the package which holds the electrochemically active ingredients and houses the external connections or terminals of the battery. The electrolyte, which is the Hquid active material and ionic conductor, is an aqueous solution of sulfuric acid. 

Lead-acid batteries remain popular because of their capability to seiwice high and low current demand, produce high voltage, provide capacity up to 100 A-h, and recharge well. Moreover, the lead-acid battery has important material and construction advantages, such as simple fabrication of lead components, the low cost of materials (lead is abundant and much less expen-... 

The electrolyte in lead-acid batteries is dilute sulfuric acid that contains the component "water". Its stability is an important factor since it can be decomposed into hydrogen and oxygen, and the two broken lines in Fig. 1 represent the borderlines of this stability. They show the equilibrium potentials of hydrogen and oxygen evolution and their dependence on the pH value. 

In the lead-acid battery, sulfuric acid has to be considered as an additional component of the charge-discharge reactions. Its equilibrium constant influences the solubility of Pb2+ and so the potential of the positive and negative electrodes. Furthermore, basic sulfates exist as intermediate products in the pH range where Fig. 1 shows only PbO (cf. corresponding Pour-baix diagrams in Ref. [5], p. 37, or in Ref. [11] the latter is cited in Ref. [8]). Table 2 shows the various compounds. 

Finally, one development results from returning to a basic idea from the dawn of the lead-acid battery, wherein the functions of support for the positive active material and of the separator are combined into one component the gauntlet separator [84] consisting of a coarsely porous, flexible support structure coated with micropo-rous polyethylene material for separation. The future has to show whether this approach will be able to meet all demands. 

Let us note finally, that tellurium has been considered as an appropriate component for the lead grid alloy in lead-acid batteries, as improving its durability, mechanical strength, and anti-corrosive ability. In investigating Pb-Te binary alloys with different contents of Te (0.01-1.0 wt%) in sulfuric acid solution it was shown recently [104] that the introduction of Te can inhibit the growth of Pb02 and increase corrosion resistance of the positive grid alloy of a lead-acid battery. By the... 

Figure 19. Depiction of the components of a lead acid battery showing the differences between theoretical and practical energy density of a lead acid battery and source of the differences.

At the present time, a large number of spent batteries are disposed of directly into the urban waste stream without proper controls. In addition to the most common systems such as zinc-carbon, alkaline manganese and nickel-cadmium, these now include, at an increasing rate, nickel-metal hydride and lithium cells. Such disposal is of serious concern because of the possible effects of battery components on the environment. Consequently, most countries are now evolving policies for collection and recycling. The majority of lead-acid batteries are recycled, but the number of recycling plants in operation worldwide for other battery systems is still very small due to the unfavourable economic balance of such operations (see Table A3.1). Some of the procedures for the disposal and recycling of battery materials are now briefly described. 

Current collector for advanced lead acid batteries Graphite used as conductive diluent in the cathode Conductive diluent in the cathode Anode-active material component... 

Active mass — The portions of a -> battery or -> accumulator which are participating in electrode reactions, i.e., in the transformation of chemical into electrical -> energy or vice versa. In a -> lead-acid battery active masses are lead dioxide and lead, with the lead or lead alloy grid serving as -> current collector and mechanical holder and all other components are not active masses. For maximum -> energy density the fraction of active mass in the overall cell weight should be as large as possible. 

Stibine is generated if nascent hydrogen can react with antimony in an acid environment, e.g. in lead-acid batteries, where antimony may be a component of the battery plates. ... 

Although lead-acid batteries are reliable and suitable for many applications, the recent trend has been, and continues to be, the development of batteries with less mass and higher capacity to power devices from wristwatches to electric cars. For applications where a battery is the key component and must provide a significant amount of power, such as for the operation of electric cars, lead-acid batteries are too heavy to be feasible. 

Sulfuric acid is a highly reactive compound and is extensively used in industry as a chemical intermediate and as a component of many industrial and commercial products. For example, it is used in fertilizers, lead-acid batteries, pigments and dyes, and as an industrial reagent in the paper, petroleum, and metal industries. It is also used in pharmaceuticals, as a food additive, and in toilet bowl cleaners. 

Traditionally, negative plates in lead-acid batteries contain a combination of carbon black, barium sulfate, and an organic additive which is usually a wood extract. These additives are collectively called an expander , although this term is often used purely for the organic component of the mix. The presence of the expander helps to... 

The eoneern over the performance of negative plates in VRLA batteries has resulted in renewed interest in the influence and mechanisms of organic additives and extensive research programmes have been carried out under the auspices of the ALABC. This work has included an assessment of 34 materials, five of which were synthetie organie compounds that were identified to have the potential to act as effective expander components in lead-acid batteries [32]. Preliminary screening tests for stability in acid, impurities and thermal stability, followed by studies of potentiostatic transients, impedance plots, and cyclic voltammograms [33], have... 

Total recovery and recycling of the lead-acid battery is relatively straightforward, as batteries are easily retrieved from most of the automotive and industrial applications in which they are used. Recovery of the lead and other components from the battery is uncomplicated because batteries are easily broken and divided into their various fractions. If a suitable combination of materials is chosen during design and construction of the battery, almost complete recovery and re-use of materials is possible at the expense of only a relatively modest amount of energy [1]. 

Once received at a secondary smelter, a lead-acid battery undergoes several processing stages to recover and treat the various component parts. In most modern plants, automatic battery breakers are used to process and recover these parts. There are many variations to battery-breaking operations throughout the world, although the outputs obtained from each operation are similar, namely, battery pastes, metallic fractions, acid, plastic components. 

Prior to leaving the manufacturing plant, all lead-add batteries should be labelled (Fig. 16.3) in accordance with prevailing national and international [8] regulations and with the international recycling symbol ISO 7000 1135, better known as the Moebius loop. Furthermore, there should be instructions for the recycling of the battery or a point of contact clearly displayed when it is at the end of its useful life. Each label should state, lead-acid battery , Pb or the words LEAD , RETURN and RECYCLE . If possible, the label should also have a bar code which contains information about the place of manufacture, the date of production, the battery type, and its components. 

The filter cake consists primarily of oxides and hydroxides of manganese and carbon compounds. A sulphuric acid plus hydrogen peroxide leach is used to dissolve all of the manganese components as sulphates. Metallic impurities and hydroxides are also dissolved. The sulphuric acid is provided from recycling lead acid batteries. Carbon and some of the remaining impurities from the manganese dioxide remain in suspension and are removed by filtration. 

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