Page 199 - Lindens Handbook of Batteries

8.12 PRIMARY BATTERIES

100
Li/SO 2 1000 Wh/kg

Alkaline - Li/MnO
MnO 2 2
Zn/HgO
10 Mg/MnO 2 Zn/Air
Specific power W/kg 5.0 Zn-carbon

Cd/HgO

2.0
(4 h/day)
1.0

0.1
1 10 20 50 100 1000
Hours of service
FIGURE 8.3 Comparison of typical performance of primary battery systems—specific power
vs. hours of service.

the discharge rate increases, the slope drops off more sharply. This occurs at higher discharge rates
for the battery types that have high-power capability.
The performance of the zinc-carbon battery falls off sharply with increasing discharge rate,
although the heavy-duty zinc chloride version of the zinc-carbon battery (see Chap. 9) gives better per-
formance under the more stringent discharge conditions. The zinc/alkaline/manganese dioxide battery,
the zinc/mercuric oxide battery, the zinc/silver oxide battery, and the magnesium/manganese dioxide
battery all have about the same specific energy and performance at 20°C. The zinc/air system has a
higher specific energy at the low discharge rates, but falls off sharply at moderately high loads, indicat-
ing its low specific power. The lithium batteries are characterized by their high specific energy, due in
part to the higher cell voltage. The lithium/sulfur dioxide battery and some of the other lithium batter-
ies are distinguished by their ability to deliver this higher capacity at the higher discharge rates.
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 Fig. 8.9. Many 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.

8.3.4 Comparison of Performance of Representative Primary Batteries
Figure 8.4 compares the performance of a number of primary battery systems in a typical button cell
configuration, size 44 IEC standard. The data are based on the rated capacity at 20°C at about the
C/500 rate. The performance of the different systems can be compared, but one should recognize that