Batteries, lead-acid

Lead acid batteries are the storage batteries most widely used at present. This is readily explained by their low price, high reliability, and good performance. Their cycle life is a few hundred charge-discharge cycles, though for some battery types, it extends to even more than a thousand cycles. 

The first working lead cell manufactured in 1859 by the French scientist, Gaston Plante, consisted of two lead plates separated by a strip of cloth coiled and inserted into a jar with sulfuric acid. A surface layer of lead dioxide was produced by electrochemical reactions in the first charge cycle. Later developments led to electrodes made by pasting a mass of lead oxides and sulfuric acid into grids of lead-antimony alloy (for lead acid batteries the electrodes are often ealled plates). 

During discharge the active materials are not fully utilized at low current drains, the degree of utilization is 40-60%. At high drains, it drops to 5-10%, which is because of the concentration polarization, that is, a sharp decrease to almost zero in sulfuric 

An increase of cycle life under high-rate working conditions, and also of high-power capability of lead acid batteries can be achieved by adding expanded graphite and some other materials to the negative active mass formulation (Pavlov et al., 2005 Muneret et al., 2005). 

7 Valve-Regulated Lead Acid Batteries (VRLA) 

Small-format lead-acid batteries with immobilized electrolyte are still used in some applications such as hand lanterns. Low-cost six or twelve-volt batteries (e.g. 6 Ah size) are used in child-driven toy cars and other sizes in emergency-light or alarm systems, kept on trickle-charge. Efforts are being made to produce bipolar systems which give 30 percent improvements. 

While an exhaustive overview of aspects of impedance investigation of a particular battery chemistry is outside the scope of this work, the present generic approach may be exemplified for each particular chemistry by looking separately at the impedance of the electrolyte, the material surface, effects of diffusion and porosity, and the boundary effects, combined in one model. Subsequently, the model can be simplified for purposes of correlation or discretized and made nonlinear if time-domain simulation is required. 

The function describing the frequency dependence of such an impedance element is equivalent to that of diffusion in Eq. (28), bnt the meaning of the parameters must be redefined as Rd = Rm, Rp = Ret, Cd = Cdi, and Cp = Cad- A complete equivalent circuit of the lead acid battery will involve serially connected elements described in previous paragraphs for the electrolyte and anode and cathode, with the addition of series resistance and inductance. 

---

Batteries, lead-acid Batteries, primary Batteries, pnmary cells... 

Because about 80% of the lead consumed in the United States is for use in lead—acid batteries, most recycled lead derives from this source of scrap. More than 95% of the lead is reclaimed. Hence, the bulk of the recycling industry is centered on the processing of lead battery scrap. 

The electrowinning process developed by Ginatta (34) has been purchased by M.A. Industries (Atlanta, Georgia), and the process is available for licensing (qv). MA Industries have also developed a process to upgrade the polypropylene chips from the battery breaking operation to pellets for use by the plastics industry. Additionally, East Penn (Lyons Station, Pennsylvania), has developed a solvent-extraction process to purify the spent acid from lead—acid batteries and use the purified acid in battery production (35). 

Secondary lead production made up over 70% of the lead produced in the United States in 1992 vs 54% in 1980. The amount of secondary lead produced was 698 X 10 t in 1988, 888 x 10 t in 1990, and 878 x 10 t in 1992. Of the 1.2 x 10 t of lead consumed in the United States in 1992, approximately 880,000 t were produced from the recycling of lead—acid batteries and 350,000 t from primary sources. A similar trend exists worldwide. In 1992, for the first time, slightly over half (51%) of the lead produced in the world came from secondary sources. 

This grade is intended for lead—acid battery appHcations. 

K. Ramus and P. Hawkins, "Lead Acid Battery Recycling and the New Isasmelt Process," 3rd European Eead Battery Conference, Munich, Germany, Oct. 1992. 

Automobile battery grids employ about 1—3 wt % antimony—lead alloys. Hybrid batteries use low (1.6—2.5 wt %) alloys for the positive grids and nonantimony alloys for the negative grids to give reduced or no water loss. The posts and straps of virtually all lead—acid batteries are made of alloys containing about 3 wt % antimony. 

Lead alloys containing 0.09—0.15 wt % calcium and 0.015—0.03 wt % aluminum are used for the negative battery grids of virtually all lead—acid batteries in the United States and are also used in Japan, Canada, and Europe. If the molten alloy is held at too low a temperature, the aluminum precipitates from solution, rises to the surface of the molten alloy as finely divided aluminum particles, and enters the dross layer atop the melt. 

Silver reduces the oxygen evolution potential at the anode, which reduces the rate of corrosion and decreases lead contamination of the cathode. Lead—antimony—silver alloy anodes are used for the production of thin copper foil for use in electronics. Lead—silver (2 wt %), lead—silver (1 wt %)—tin (1 wt %), and lead—antimony (6 wt %)—silver (1—2 wt %) alloys ate used as anodes in cathodic protection of steel pipes and stmctures in fresh, brackish, or seawater. The lead dioxide layer is not only conductive, but also resists decomposition in chloride environments. Silver-free alloys rapidly become passivated and scale badly in seawater. Silver is also added to the positive grids of lead—acid batteries in small amounts (0.005—0.05 wt %) to reduce the rate of corrosion. 

Wrought or extmded lead—teUurium (0.035—0.10 wt %) aUoys produce extremely fine grains. The binary aUoy is, however, susceptible to recrysta11i2ation. The addition of copper or sUver reduces grain growth and retains the fine grain si2e. Because teUurium is a poison for sealed lead—acid batteries, the teUurium content of lead and lead aUoys used for such purposes is usuaUy restricted to less than 1 ppm. 

The excellent corrosion-resistant lead dioxide, Pb02, film formed on anodes and lead—acid battery positive grids in sulfuric acid has enabled lead insoluble anodes and lead—acid batteries to maintain the dominant positions in their respective fields. 

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. 

Pure lead for lead—acid battery appHcation. 

Selenium acts as a grain refiner in lead antimony alloys (114,115). The addition of 0.02% Se to a 2.5% antimonial lead alloy yields a sound casting having a fine-grain stmcture. Battery grids produced from this alloy permit the manufacture of low maintenance and maintenance-free lead—acid batteries with an insignificant loss of electrolyte and good performance stability. 

Trace quantities of arsenic are added to lead-antimony grid alloys used ia lead—acid batteries (18) (see Batteries, lead acid). The addition of arsenic permits the use of a lower antimony content, thus minimising the self-discharging characteristics of the batteries that result from higher antimony concentrations. No significant loss ia hardness and casting characteristics of the grid alloy is observed (19,20). 

The U.S. primary battery market is divided according to the chemical system used in the batteries, whereas the secondary battery market is usually divided according to usage. The 1989 estimate of the total battery market is given in Table 1. The lead—acid battery accounts for over 85% of the secondary battery market. 

Battery electrolytes are concentrated solutions of strong electrolytes and the Debye-Huckel theory of dilute solutions is only an approximation. Typical values for the resistivity of battery electrolytes range from about 1 ohmcm for sulfuric acid [7664-93-9] H2SO4, in lead—acid batteries and for potassium hydroxide [1310-58-3] KOH, in alkaline cells to about 100 ohmcm for organic electrolytes in lithium [7439-93-2] Li, 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. 

The lead—acid battery is one of the most successful electrochemical systems and the most successful storage battery developed. In 1988 total battery sales, excluding Eastern European central economy countries, were more than 17 biUion (1). Lead—acid battery sales accounted for about 57% of that figure. About 80% of the lead [7439-92-1] (qv), Pb, consumption in the United States was for batteries in that year. 

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.

Fig. 2. Cutaway view of a tubular positive lead—acid battery, (1) Positive tubular plate (2) iiegatwe plate (3) separator (4) connecting strap (5) ceU cover (6)...

In the 1990s, the use of batteries in electric vehicles and for load leveling is being revived partly for environmental reasons and partly because of scarce energy resources. Improvements in battery performance and life, fewer maintenance requirements, and automatic control systems are making these appHcations feasible. Research and development is ongoing all over the world to develop improved lead—acid batteries as weU as other systems to meet these needs. 

---