Page 358 - Lindens Handbook of Batteries

LiTHiUM PriMAry BATTerieS 14.23

service hours and discharge temperature. The battery weight or volume is calculated by dividing the
value of the specified current (in amperes) by the value of amperes per kilogram or amperes per liter
obtained from the ordinate.

Shelf Life. The Li/SO battery is noted for its excellent storage characteristics, even at tempera-
2
tures as high as 70°C. Most primary batteries lose capacity while idle or on standby due to anode
corrosion, side chemical reactions, or moisture loss. With the exception of the magnesium battery,
most of the conventional primary batteries cannot withstand temperatures in excess of 50°C and
should be refrigerated if stored for long periods. The Li/SO battery, however, is hermetically
2
sealed and protected during storage by the formation of a film on the anode surface. Capacity
losses during stand are minimal. if cells are partially discharged and then stored, the self-discharge
rate is accelerated.
19
Data on 2-year old BA-5590 batteries consisting of 10 Li/SO D-size cells discharged in series
2
at 2 A at +21 and -30°C showed a 6.5% capacity loss at the higher temperature but no loss at the
lower temperature. Fourteen-year storage data was also obtained on BA-5598 batteries consisting of
five “squat” D-size cells in series. These batteries showed only an 8% capacity loss when discharged
at room temperature at 2 A, but virtually no loss at cold temperature. in both cases, a lower operating
voltage was observed after storage. Using multiple groups of batteries, stored for 4, 6 and 14 years
under ambient conditions, the data shown in Fig. 14.14 were obtained. The capacity loss for the
first two years is approximately 3%/yr, but the rate of loss decreases significantly after that period.
High-temperature storage of batteries was also carried out at +70 and +85°C, as shown in Fig. 14.15.
At 70°C, these batteries showed 92% capacity retention after 1 month and 77% capacity retention
after five months. At 85°C, 82% capacity retention was observed after one month’s storage. This
study concluded that there was no obvious benefit to making long-term storage predictions based on
accelerated aging tests at high temperature.

100%
95%

90%
Percent of original capacity 80%
85%

75%

70%
65%
60% Actual data
3%/yr loss prediction
55%

50%
0 5 10 15
Storage time (years)
FIGURE 14.14 Capacity retention of Li/SO batteries after ambient storage and
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discharge at the 2 A rate.