Lead-acid cell

Table 1 gives the calculated open circuit voltages of the lead—acid cell at 25°C at the sulfuric acid molalities shown. The corrected activities of sulfuric acid from vapor pressure data (20) are also given. 

Table 1. Thermodynamic Values for the Lead-acid Cell at 25°C...

Table 2. Temperature Coefficients of the Lead—Acid Cell, Ej mV...

An excellent review covers the charge and discharge processes in detail (30) and ongoing research on lead—acid batteries may be found in two symposia proceedings (32,33). Detailed studies of the kinetics and mechanisms of lead —acid battery reactions are pubUshed continually (34). Although many questions concerning the exact nature of the reactions remain unanswered, the experimental data on the lead—acid cell are more complete than for most other electrochemical systems. 

The separator must be stmcturaHy sound to withstand the rigors of battery manufacturing, and chemically inert to the lead—acid cell environment. Numerous materials have been used for separators ranging from wood, paper, and mbber to glass and plastic. The majority of separators used are either nonwoven—bound glass or microporous plastic such as PVC or polyethylene. 

Electrolyte ia a Lead—Acid Cell," LABAT-89 Conference, Varna, Bulgaria, 1989. 

Plante or Lead-Acid Cell PbO + Pb -b H3SO4 — 2PbS04... 

J. Burbank, A.C. Simon, E. Willihnganz, The lead acid cell, in Advances in Electrochemistry and Electrochemical Engineering, Vol. 8, John Wiley, New York, 1971, p. 170. 

E° equilibrium potential of H2 evolution in lead-acid cell II.4... 

Flaving had over 150 years of technical development behind them, lead-acid batteries can be custom-tailored to specific applications, such as those requiring deep discharge cycles (e.g., where the batteries are used as the sole power source for electrical equipment) and for battery backup uses such as in large uninterruptible power supply systems in data centers. Moreover, lead-acid cells not only have low internal resistance but also experience no memory effect as do some more exotic cell designs, such as NiCads. This enables these cells to produce enormous currents and have a moderately long, predictable life.1... 

The market for batteries is huge, with new types and applications being developed all the time. For example, a watch battery is a type of silver oxide cell silver in contact with silver oxide forms one half-cell while the other is zinc metal and dications. Conversely, a car battery is constructed with the two couples lead(IV) lead and lead(IV) lead(II). The electrolyte is sulphuric acid, hence this battery s popular name of lead-acid cell (see further discussion on p. 347). 

The first difference between these two batteries is the voltage they produce a watch battery produces about 3 V and a lead-acid cell about 2 V. The obvious cause of the difference in emf are the different half-cells. The electrode potential E is the energy, expressed as a voltage, when a redox couple is at equilibrium. 

By contrast, secondary batteries may be reused after regenerating their original redox chemicals. This is achieved by passing a current through the battery in the opposite direction to that during normal battery usage. The most common examples of secondary batteries are the lead-acid cell (there is one inside most cars) and nickel-cadmium batteries (commonly called NiCad batteries). 

The lead-acid cell was invented by Plante in 1859, and has remained more-or-less unchanged since Faurd updated it in 1881. The lead-acid cell is the world s most popular choice of secondary battery, meaning it is rechargeable. It delivers an emf of about 2.0 V. Six lead-acid batteries in series produce an emf of 12 V. 

Properties of lead-acid cells, important from the practical point of view, related, for example, to charge/discharge process and its mechanism, conductivity, and so on are studied using different electrochemical techniques, the most powerful one being electrochemical impedance spectroscopy [355-358]. 

By far the largest sector of the battery industry worldwide is based on the lead-acid aqueous cell whose dominance is due to a combination of low cost, versatility and the excellent reversibility of the electrochemical system, Lead-acid cells have extensive use both as portable power sources for vehicle service and traction, and in stationary applications ranging from small emergency supplies to load levelling systems. In terms of sales, the lead-acid battery occupies over 50% of the entire primary and secondary market, with an estimated value of 100 billion per annum before retail mark-up. 

Fig. 5.1 Original Planl spiral wound lead-acid cell...

The lead-acid cell can be represented schematically as having a negative electrode of porous lead (lead sponge) and a positive electrode of lead dioxide, Pb02, both immersed in an aqueous solution of sulphuric acid ... 

Fig. 5.2 Approximate open circuit voltage and electrolyte density as a function of percentage service capacity for the lead-acid cell...

Fig. 5.6 (a) Tubular plates for lead-acid cells, (b) Cross-section showing central lead current collector, active material and porous separators... 

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