Mercuric oxide/zinc battery

Miniature zinc—mercuric oxide batteries have a zinc anode and a cathode containing mercuric oxide... 

Eig. 11. Typical discharge curve comparison for zinc—mercuric oxide batteries (-) model 325, HgO, and (-... 

Miniature zinc—mercuric oxide batteries may be made with either KOH or NaOH as the electrolyte. Cells having KOH operate more efficiently than those having NaOH at high current drains (Eig. 12) because of the higher conductivity of KOH. On the other hand, batteries with KOH are more difficult to seal, cells with NaOH are more resistant to leakage. 

Eig. 12. Comparison of battery efficiency for miniature zinc—mercuric oxide cells containing KOH or NaOH electrolyte (21). 

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. 

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. 

Miniature zinc-mercuric oxide batteries function efficiently over a wide range of temperatures and have good storage life. 

Although die zinc-mercuric oxide battery has many excellent qualities, increasing environmental concerns have led to a deemphasis in the use of this system. The main environmental difficulty is in the disposal of the cell. Both the mercuric oxide in the fresh cell and the mercury rcducrion product in the used cell have long-term toxic effects. 

Ruben cell — This is a zinc-mercuric oxide alkaline cell, more commonly called a mercury -> battery, a type of primary (nonrechargeable) cell, developed by Samuel Ruben during World War II in response to a requirement for batteries with a high capacity-to-volume ratio which would withstand storage under tropical conditions. It was licensed to the RR. Mallory Co., which... 

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,... 

Fig. 13. Effect of temperature on discharge efficiency (a) at 270 mA h of miniature zinc-mercuric oxide batteries type EP675E, and (b) at 175 mA h of...

Fig. 14. Retention of discharge capacity of miniature zinc—mercuric oxide batteries after storage at temperatures of A, 40°C B, 20°C and C, 0°C (21).

Although the zinc—mercuric oxide battery has many excellent qualities, increasing environmental concerns has led to a de-emphasis in the use of this... 

Fig. 15. Relative discharge curves for (-) zinc—silver oxide, and (—) zinc—mercuric oxide batteries. Cells are of equal volume (21).

The goal of these and other researchers was to develop a totally implantable pacemaker. Bioengineer Wilson Greatbatch and heart surgeon William Chardack achieved this milestone with their first successfiil human implant in 1960. Greatbatch used then-novel transistors and an epoxy-encased Ruben-Mallory zinc mercuric oxide battery in his design. [5]... 

Cardiac pacemakers are generally employed when the cardiac rhythm is either abnormal or too slow. To rectify this problem, doctors prescribe implanted pacemakers that detect the slow heart rate and send impulses to stimulate the muscle using microelectronic circuits. The life of these devices developed before 1973 and incorporating zinc-mercuric-oxide (Zn-HgO) batteries was only between 12 and 18 months. When Li-l2 batteries became available around 1975, the battery life was extended to more than 10 years. The life of devices with batteries developed after 2008 could be more than 15 years. 

Cadmium/Mercuric Oxide Battery. The substitution of cadmium for the zinc anode (the cadmium/mercuric oxide cell) results in a lower-voltage but very stable system, with a shelf life of up to 10 years as well as performance at high and low temperatures. Because of the lower voltage, the watthour capacity of this battery is about 60% of the zinc/mercuric oxide battery capacity. Again, because of the hazardous characteristics of mercury and cadmium, the use of this battery is limited. 

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. 

TABLE 11.1 Characteristics of the Zinc/Mercuric Oxide and Cadmium/Mercuric Oxide Batteries... 

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.)... 

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