Zinc/mercuric oxide batteries temperature

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

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).

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. 

FIGURE 11.7 No-load voltage vs. temperature, zinc/mercuric oxide battery. 

The zinc/mercuric oxide battery is best suited for use at normal and elevated temperatures from 15 to 45°C. Discharging batteries at temperatures up to 70°C is also possible if the discharge period is relatively short. The zinc/mercuric oxide battery generally does not perform well at low temperatures. Below 0°C, discharge efficiency is poor unless the current drain is low. Figure 11.9 shows the effect of temperature on the performance of two types of zinc/mercuric oxide batteries at nominal discharge drains. 

Zinc/mercuric oxide batteries have good storage characteristics. In general they will store for over 2 years at 20°C with a capacity loss of 10 to 20% and 1 year at 45°C with about a 20% loss. Storage at lower temperatures, such as down to -20°C, will, as with other battery systems, increase storage life. 

The performance of the zinc/mercuric oxide cell at various temperatures and loads is summarized in Figs. 11.12 and 11.13 on a weight and volume basis. These data, based on the performance of a 800 mAh battery with a dispersed anode, can be used to approximate the performance of a zinc/mercuric oxide battery. 

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. 

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