Page 346 - Lindens Handbook of Batteries

LiTHiUM PriMAry BATTerieS 14.11

4.0
Li/SOCl 2
3.5

3.0
Voltage, V 2.5 Li/SO 2

2.0

1.5

1.0
0 10 20 30 40 50 60
Hours of service
FIGURE 14.2 Comparison of performance of Li/SO and Li/SOCl C-size batteries; 100-mA
2
2
discharge load at 20°C.
storage. Li/SOCl cells have been fabricated in many sizes and designs ranging from small button
2
and cylindrical cells with capacities below 1 Ah, to large prismatic cells with capacities as high as
10,000 Ah. Low-rate cells have been used successfully in many applications, especially as memory
backup, for many years; high-rate cells are used in special applications.
The lithium/sulfuryl chloride (Li/SO Cl ) battery has potential advantages because of its higher
2
2
voltage (3.9 open-circuit voltage) and resultant higher specific energy. Suitable cathode electrode
formulations and cell designs have been investigated to achieve the full capability of this electro-
chemical system. Figure 14.3 shows a comparison of the cathode polarization for Li/SO Cl and Li/
2
2
SOCl batteries. Halogen additives such as chlorine have been used as a means to improve perfor-
2
mance. Halogen additives are also used in some cells.
Calcium has been investigated as an anode material in place of lithium in thionyl chloride cells.
Safer operation was anticipated with calcium since its melting temperature of 838°C is not likely to
be reached by any internally driven cell condition. While the discharge voltage is about 0.4 V lower
than for the Li/SOCl cell (open-circuit voltage is 3.25 V), the Ca/SOCl cell has a flat discharge pro-
2
2
file and about the same volumetric ampere-hour capacity. Shelf-life characteristics are also similar to
those of the lithium anode cell. 9,10 However, calcium is significantly more difficult to process than
lithium and passivation is a more significant factor. To date, no calcium-thionyl chloride batteries
have been commercialized. 4.0
Cathode voltage vs. Li, V 3.8 SO Cl 2
2
3.6

3.4
3.2

0.1 1.0 10 SOCl 2
Current density, mA/cm 2
FIGURE 14.3 Comparison of cathode polarization curves,
Li/SO Cl vs. Li/SOCl batteries. 8
2 2 2