Page 315 - Battery Reference Book

27/12 High-temperature thermally activated primary batteries

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alloys have also been used) and an iron sulphide cath- .-
h
C
ode. The lithium-boron alloys investigated contain 70
37% lithium and 63% boron. These lithium-boron 3.0 $
0
liquid electrodes have not yet reached the production -- ' !
-
'.
I
stage. ', 2.5 2
The load-carrying capacity of this LiA1-FeS2 Y
(abbreviated LAN-FeS2) system is two to three times 2.0
better than that of the calcium-calcium chromate
system. The LAN-FeS2 system has a low and constant 20
internal impedance which makes it ideal for both long
discharge lives and pulse applications.
This type of battery can now replace many remotely I
activated silver oxide-zinc applications, resulting in an 'e -50 -25 0 25 50
equal or smaller size, lightweight battery at lower cost. 2 Temperature ("C)
Figure 27.15 Activated life and rise time of an Li(Si)/FeSp thermal
27.3.1 Production batteries battery (Courtesy of Catalyst Research Corporation)
Figure 27.14 shows the discharge curves comparing an
LiAWeS2 cell with a magnesium-iron disulphide cell capability, some of the advantage is due to size and
as well as with a typical calcium-calcium chromate design differences, which caused the smaller LiSi
cell. Both the magnesium and lithium anode cells battery to cool more rapidly.
give longer performance than the calcium cell; the The performance data for the lithium-iron disul-
main difference between magnesium and lithium is phide thermal battery cover a range from high power
the higher voltage of the lithium cell. Figure 27.15 (4 min rate) to long life (40-60 min rate). Although the
shows the activated life time and rise time for a 60 min, data are still based on prototype batteries, they already
28 V, 0.5 A thermal battery with a volume of 400 cm3 show a magnitude of improvement over the conven-
in the Li(Si)/LiC1.KC1/FeSz electrochemical system. tional thermal battery systems. The advantages are so
The rise time decreases with increasing temperature; pronounced that the lithium-iron disulphide thermal
the activated life, however, maximizes in the range of battery, it can be confidently predicted, will be the
25 -50°C. dominant system in the 1990s.
Table 27.4 presents data on two types of lithium- Figure 27.16 shows the design of a modem lithium-
iron disulphide thermal battery and illustrates the iron disulphide thermal battery.
advantage of the lithium anode systems. While the The pyrotechnic discs are made from iron and potas-
liquid lithium anode battery shows better performance sium perchlorate powders. The thinner the pyrotechnic
than the lithium alloy battery, particularly in its rate the more rapid will be the meeting of the electrolyte