Button batteries zinc/mercuric oxide

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. 

A third primary dry cell is the zinc-mercuric oxide cell depicted in Figure 17.7. It is commonly given the shape of a small button and is used in automatic cameras, hearing aids, digital calculators, and quartz-electric watches. This battery has an anode that is a mixture of mercury and zinc and a steel cathode in contact with solid mercury(II) oxide (HgO). The electrolyte is a 45% KOH solution that saturates an absorbent material. The anode half-reaction is the same as that in an alkaline dry cell,... 

Volumetric energy density is, at times, a more useful parameter than gravimetric specific energy, particularly for button and small batteries, where the weight is insignificant. The denser batteries, such as the zinc/mercuric oxide battery, improve their relative position when compared on a volumetric basis, as shown in Table 7.4 and Fig. 7.9. The chapters on the individual battery systems include a family of curves giving the hours of service each battery system will deliver at various discharge rates and temperatures. 

The button configuration of the zinc/mercuric oxide battery is shown in Fig. 11.2. The top is copper or copper alloy on the inner face and nickel or stainless steel on the outer face. This part may also be gold plated, depending on the application. Within the top is a dispersed... 

FIGURE 11.2 Zinc/mercuric oxide battery—button configuration. Courtesy of Duracell, Inc.)... 

Impedance for the zinc/mercuric oxide button batteries was usually measured at a frequency of 1 kHz because of their use in hearing-aids. ... 

Discharge profiles for the DAB and DA675-size zinc/air button batteries are presented in Fig. 13.6. As the air cathode in the cell is not chemically altered during discharge, the voltage remains quite stable. Data for the zinc/mercuric oxide and zinc/silver oxide batteries are provided for comparison. On continuous discharge at the loads shown, the zinc/air battery will deliver twice the service of the other batteries of the same size. The DAB battery, which has less than half the volume of the other batteries, outperforms the larger metal oxide batteries. 

The button cells that provide the energy for watches, electronic calculators, hearing aids, and pacemakers are commonly alkaline systems of the silver oxide-zinc or mercuric oxide-zinc variety. These alkaline systems provide a vei y high energy density, approximately four times greater than that of the alkaline zinc-manganese dioxide battery. 

Mercuric oxide batteries are being gradually replaced by new technologies such as silver oxide and zinc-air button batteries that contain less mercury. 

Miniature button-type batteries, using the same zinc/alkaline-manganese dioxide chemistry as cylindrical cells, compete with other miniature battery systems such as mercuric oxide, silver oxide, and zinc/air. Table 10.2 shows the major advantages and disadvantages of miniature alkaline-manganese dioxide batteries in comparison to other miniature batteries. 

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