Page 311 - Battery Reference Book

2718 High-temperature thermally activated primary batteries

Table 27.1 Characteristics of thermal batteries available from
Eagle Picher
EAO-6266: 101.6 mm diameter five-cell stacks 5' IC
Voltage 27 3z 3V
Life at 71"C, 221 s -----
at 24"C, 366 s ' I,---,- --- _--- -.
at -54"C, 317 s \
Load 33 A nominal Amps x 100 \
Size 121 mm diameter x 193.7mm long
Weight 5.2kg
Watt hours 89.1 = 17.2Whkg 0 30 60 90120150180210240270300330360
EAP-6230: 101.6 mm diameter five-cell stacks, DEB type Time (s)
Voltage 28.5 f 3.5V Figure 27.10 Performance of an Eagle Picher EAP-6273 thermal
Life at 38T, 24min battery under 0.024 L2 load (Courtesy of Eagle Picher)
at 5"C, 16min
Load 4.3 A nominal
Size 122 mm diameter x 104 mm long To a large extent calcium anode thermal batteries
Weight 2.86kg are being displaced by ones using lithium rich alloys
Watt hours 48.3 = 16.9 W ldkg as discussed below. Lithium types avoid unwanted
EAP-6251: 76 mm diameter parallel stacks side reactions which characterize the calcium types
Voltage 27 f 3V which have electrochemical efficiencies down to 20%
Life at 71"C, 110s of theoretical values.
at 24T, 200 s A comparison of some of the important characteris-
at -40"C, 140s tics of the calcium-calcium chromate and LAN-FeS2
Load 23 A nominal systems is given in Table 27.2.
Size 94mm diameter x 145 mm long Table 27.3 summarizes the characteristics of the
Weight 3 kg
Watt hours 31 = 10.4Whkg main types of thermal battery.
EAT-6261: 76 mm diameter, parallel stacks
Voltage 1-33 * 5.5 v 27.2 Lithium anode thermal batteries
-33 * 5.5 v
Life at 71"C, 170s Since lithium metal is molten at thermal battery dis-
at 24"C, 200s charge temperatures, it is retained on high surface
at -56"C, 135s area metals by immersion of the metal matrix in
Load 4.2 A each section molten lithium to form anodes. Often this structure
Size 89 mm diameter x 117 mm long is contained within a metal cup to prevent leakage
Weight 1.9kg during cell operation. Another method is the fabrica-
Watt hours 20 = 8.1 Whkg tion of lithium alloy anodes, such as lithium-boron,
(138.6 x 2 sections) lithium-aluminium and lithium- silicon, which are
EAP-6273 solid at battery discharge temperatures and thus offer
Voltage 12 * 3V the possibility of simpler construction. However, the
Life at 24"C, 350s
Load 500 A nominal lithium alloys are more difficult to fabricate than the
Size 177.8 mm diameter x 406 mm long metal matrix anodes and do not achieve this same peak
Weight 20.4 kg current density. Most of the lithium anode batteries
Watt hours 583.3 = 38.6 Wh/kg currently use the lithium chloride-potassium chloride
electrolyte and an iron disulphide (FeS2) cathode.
The lithium-iron disulphide electrochemistry is
more straightforward than that of the calcium chromate
pipe is cut to length and welded to two copper bars. cell. The overall reaction is:
Connections are made to allow water to flow through
the pipe. A 1OOOA current shunt is bolted into series First step: 2Li + FeS2 + Li2S + FeS (27.3)
with one copper bar to provide current monitoring Second step: 2Li + FeS = LizS + FeS (27.4)
capabilities.
The performance of the EAP-6273 is shown in Nominal voltages are 1.6V for the first step and
Figure 27.10. Essentially the battery performs as a 1.2V for the second step. Lithium-iron disulphide
12 V battery delivering 550 A. Additional current could batteries are usually only discharged to the end of
be drawn on if necessary, as would be required for an the first step, i.e. at 1.6V, giving a specific energy
electric motor starter. However, the power developed density of 640 W fig-' compared to 250 W h/Kg-'
would be capable of starting any 12 V vehicle requiring for the lead acid battery and 120OWh/Kg-' for the
up to 800A of peak current loads. lithium-sulphur dioxide battery.