Automotive lead-acid battery

It is estimated that over 14 billion alkaline Zn-Mn02 cells and 30 billion carbon-zinc cells were made worldwide in 2003. This compares to the about 500 million lead acid automotive batteries that were made in the same period. 

Replacement of the antimony-lead alloy in the conventional lead-acid automotive battery with a 0.1% Ca—Pb grid alloy improves the conductivity and current capability of the cell, and significantly reduces gassing, permitting the cell to be closed thus preventing water loss and extending battery life. 

A 12-V lead-acid automotive battery consists of six voltaic cells in series, each producing 2 V. The cathode of each cell is lead dioxide (Pb02) packed on a lead grid ( FIGURE 20.19). The anode of each cell is lead. Both electrodes are immersed in sulfuric acid. 

Looking beyond bottle recycling, over 200 million pounds of polypropylene are recycled each year from automotive batteries [14]. The lead and acid are also recovered. The recycling rate for lead-acid automotive batteries is greater than 90% according to Battery Council International (www.batterycouncil.org). 

Overall, the lead-acid automotive battery is close to 60 per cent lead and is typically made up of the following components ... 

As an example, indicative costs are provided for the treatment of scrap lead-acid automotive batteries to produce refined lead using battery breaking and paste desulfurisation, followed by melting and reduction in a short rotary furnace, as described in Chapters 10 and 11. A typical small scale unit handling 35 000 tonnes per year of batteries is considered with a lead production of around 19 000 tonnes per year. Relevant production data is as follows ... 

Lead-acid automotive batteries are prohibited from MSW disposal facUities in 37 U.S. states, primarily due to concern about the effects of lead. Several states impose deposits on batteries. Effective recycUng programs for these batteries have existed for a number of years. The Battery Council International reports a 1996 recycling rate of 96.5 percent for lead-acid batteries. PP makes up about 7 percent of the battery, by weight, and is recovered along with the lead. The primary market for the recovered PP is new battery cases. A typical battery contains 60 to 80 percent recycled PP. ... 

Typical dimensions for the /5-alumina electrolyte tube are 380 mm long, with an outer diameter of 28 mm, and a wall thickness of 1.5 mm. A typical battery for automotive power might contain 980 of such cells (20 modules each of 49 cells) and have an open-circuit voltage of lOOV. Capacity exceeds. 50 kWh. The cells operate at an optimum temperature of 300-350°C (to ensure that the sodium polysulfides remain molten and that the /5-alumina solid electrolyte has an adequate Na" " ion conductivity). This means that the cells must be thermally insulated to reduce wasteful loss of heat atjd to maintain the electrodes molten even when not in operation. Such a system is about one-fifth of the weight of an equivalent lead-acid traction battery and has a similar life ( 1000 cycles). 

The general construction of the lead-acid automotive or starting lighting ignition (SLI) battery using the above principles is shown in Figure 10.1. 

Recent work has shown that two parameters, namely low electrical resistance and low senarator thickness, have a profound effect on cold cranking performance of low-maintenance calcium-lead alloy automotive batteries. Figure 18.20 and 18.21 show the beneficial effect of decreasing the electrical resistance of the separator on the cell voltage in tests run at — 18°C and —30°C on low-maintenance lead-acid batteries. 

Because the nickel—iron cell system has a low cell voltage and high cost compared to those of the lead—acid battery, lead—acid became the dorninant automotive and industrial battery system except for heavy-duty appHcations. Renewed interest in the nickel—iron and nickel—cadmium systems, for electric vehicles started in the mid-1980s using other cell geometries. 

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. 

Fig. 1. Cutaway view of an automotive SLI lead—acid battery container and cell element.

World production of lead—acid batteries in 1988, excluding the Eastern European central economy countries, has been estimated at 9.45 biUion. The automotive market was 6743 million or 211.6 million units. Industrial battery sales were 2082 million and consumer battery sales were 454 million. Motorcycle batteries accounted for an additional 170 million or 25 million units. Most batteries are produced in the United States, Western Europe, and Japan, but smaller numbers are produced worldwide. The breakdown in sales for the three production areas foUows. Automotive battery sales were 2304 million in the United States, 1805 in Western Europe, and 945 million in Japan. Industrial battery sales were 525 million in the United States, 993 million in Western Europe, and 266 million in Japan. Consumer battery sales were 104 million in the United States, 226 million in Japan, and 82 million in Western Europe. More than half of all motorcycle batteries are produced in Japan and Taiwan (1). 

Whereas automotive batteries have the majority of the market, other types of lead—acid batteries, such as sealed and small maintenance-free varieties, are making inroads into various appHcations. The automotive battery s operating environment has changed substantially in the last 10 years. Underhood temperature has risen and electrical loads have increased. This trend is expected to continue as car manufacturers reevaluate thek design strategies and objectives. Battery design is changing to meet these needs. 

Reprinted from W. Bohnstedt, Automotive lead/acid battery separators a global overview, J. Power Sources, 1996, 59, 45-50, with kind permission from Elsevier Science S.A., Lausanne. 

Table 2. Automotive lead-acid battery production 1997 (million kWh, estimate)...

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