Zinc/silver oxide primary batteries

TABLE 12.1 Major Advantages and Disadvantages of Zinc/Silver Oxide Primary Batteries ... 

FIGURE 18.4 Assembly of automatically activated zinc/silver oxide primary battery with tubular coil reservoir. Courtesy of Eagle-Picher Industries.)... 

FIGURE 18.12 Service life of zinc/silver oxide primary batteries. (Courtesy of... 

The cost of high-performance primary zinc/silver oxide batteries is dependent on the specifications to which they are built and the quantity involved. Manual-type batteries may cost anywhere from 5 to 15 per Watthour remote-activated types will cost about 15 to 20 per Watthour. When the price of silver is high, material cost becomes one of the chief disadvantages of these batteries. There are many applications, however, in which no other technology can meet the high energy density of the zinc/silver oxide primary system. 

Battery systems of complex design and structure using—at least for one electrode—expensive materials are (for economic reasons) mainly conceived as storage batteries. Primary (and "reserve") versions of the zinc/silver oxide battery [(-) Zn/KOH/AgO (+)] — as a first example—are only used in particular cases where the question of cost is not crucial, e.g., for marine [26-28] and space applications [29]. 

Zinc-silver oxide batteries as primary cells are known both as button cells, e.g., for hearing aids, watches, or cameras, and for military applications, usually as reserve batteries. Since the latter after activation have only a very short life (a few seconds to some minutes), a separation by cellulo-sic paper is generally sufficient. 

Mineral wool, asbestos substitute, 3 314t Miniature alkaline primary cells, 3 449 59 cutaway view, 3 449 divalent zinc-silver oxide batteries, 3 454 55... 

In Scotland, the cost of domestic mains electricity is 0.0713/kWh (in 1997). A D-size Leclanchd cell, delivering say 5 Wh, currently retails at 0.50. Thus, energy from the primary battery costs I00/kWh - a factor of over 1000 more expensive. For a 150 mWh zinc-silver oxide button cell, retailing at 1.50, the cost of energy is over 10 000/kWh ... 

The primary objective of miniature battery design is to maximize the energy density in a small container. A compromise must be reached, however, since volumetric energy density decreases as cell volume decreases and the dead volume due to containers, seals, etc. becomes increasingly significant. A plot of energy density as a function of total volume is given in Fig. 3.28 for the zinc-mercuric oxide and zinc-silver oxide systems. 

Batteries, lead-acid -zinc-silver oxide [BATTERIES - PRIMARY CELLS] (Vol 3) - [BATTERIES - SECOND ARYCELLS - LEAD-ACID] (Vol 3) -arsenic m [ARSENIC AND ARSENIC ALLOYS] (Vol 3) -barium m [BARIUM] (Vol 3) -use of lead compounds [LEAD COMPOUNDS - LEAD SALTS] (Vol 15)... 

The Zn negative electrode material, or anode, and electrolyte solution are similar to other primary alkaline battery types, like zinc-air and zinc-silver oxide (Zn/ Ag20). Zinc powder is mixed with a gelling agent like polyacrylic acid and a KOH-Zn0-H20 electrolyte. 

Zinc/Silver oxide valency 1 or 2 1.55 350 650 Primary battery in button cell design... 

The primary zinc/silver oxide batteries are manufactured mainly in the button cell configuration in a wide range of sizes from 5 to 250 mAh. Most of these batteries are now prepared from the monovalent silver oxide (Ag20). 

The more familiar types of primary alkaline systems are the zinc/manganese dioxide, zinc/ mercuric oxide, and zinc/silver oxide batteries. These, typically, use potassium or sodium hydroxides, in concentrations from 25 to 40% hy weight, as the electrolyte, which functions primarily as an ionic conductor and is not consumed in the discharge process. In simple form, the overall discharge reaction for these metal oxide cells can be stated as... 

The performance advantages of several types of lithium batteries compared with conventional primary and secondary batteries, are shown in Secs. 6.4 and 7.3. The advantage of the lithium cell is shown graphically in Figs. 7.2 to 7.9, which compare the performance of the various primary cells. Only the zinc/air, zinc/mercuric oxide, and zinc/silver oxide cells, which are noted for their high energy density, approach the capability of the lithium systems at 20°C. The zinc/air cell, however, is very sensitive to atmospheric conditions the others do not compare as favorably on a specific energy basis nor at lower temperatures. 

The electrochemical reactions associated with the discharge of a zinc/silver oxide battery as a primary system are generally considered to proceed as follows. The cathode or positive electrode is silver oxide and may be either Ag20 (monovalent), AgO (divalent), or a mixture of the two. The anode or negative electrode is metallic zinc, and the electrolyte is an aqueous solution of potassium hydroxide. The chemical reactions and the associated voltages at standard conditions are... 

Other alkaline primary cells couple zinc with oxides of mercury or silver and some even use atmospheric oxygen (zinc—air cell). Frequendy, zinc powder is used in the fabrication of batteries because of its high surface area. Secondary (rechargeable) cells with zinc anodes under development are the alkaline zinc—nickel oxide and zinc—chlorine (see Batteries). 

There are two major types of household batteries (a) Primary batteries are those that cannot be reused. They include alkaline/manganese, carbon-zinc, mercuric oxide, zinc-air, silver oxide, and other types of button batteries, (b) Secondary batteries are those that can be reused secondary batteries (rechargeable) include lead-acid, nickel-cadmium, and potentially nickel-hydrogen. 

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