Linden D., Reddy T.B. (eds.) Handbook of batteries

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LITHIUM BATTERIES 14.25

FIGURE 14.13 Service life of high-rate Li / SO

batteries; 2.0-V end voltage.

Service Life. The capacity or service life of the Li /SO

battery at various discharge rates

given in Fig. 14.13. The data are normalized for a 1-kg or 1-L size battery and presented in

terms of hours of service at various discharge rates. The linear shape of this curve is again

indicative of the capability of the Li/ SO

battery to be efﬁciently discharged at these extreme

conditions. This data can be used in several ways to calculate the approximate performance

of a given battery or to select a Li/SO

battery of suitable size for a particular application,

recognizing that the speciﬁc energy of the larger-size batteries is higher than that of the

smaller ones.

The service life of a battery at a given current load can be estimated by dividing the

current (in Amperes) by the weight or volume of the battery. This value is located on the

ordinate, and the service life, at a speciﬁc current and temperature, is read of the abscissa.

The weight or volume of a battery needed to deliver a required number of hours of service

at a speciﬁed current load can be estimated by locating a point on the curve corresponding

to the required 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 Am-

peres 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

temperatures as high as 70

⬚C. Most primary batteries lose capacity while idle or on stand

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 sealed and protected during storage by the formation of a ﬁlm on

the anode surface. Capacity losses during stand are minimal.

14.26 CHAPTER FOURTEEN

Recent data

on two-year old BA-5590 batteries consisting of 10 Li/SO

D-size cells

discharged in series at 2 amps 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 ob-

tained 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 amps, 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 was obtained. The capacity loss for the ﬁrst two

years is approximately 3%/year, 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.

STORAGE TIME (Years)

0 5 10 15

100%

95%

90%

85%

80%

75%

70%

65%

60%

55%

50%

% of ORIGINAL CAPACITY

ACTUAL DATA

3%/YEAR LOSS

PREDICTION

FIGURE 14.14 Capacity retention of Li/ SO

batteries after ambient storage and

discharge at the 2 amp rate.

LITHIUM BATTERIES 14.27

100%

95%

90%

85%

80%

75%

70%

65%

70 Deg C

85 Deg C

0 1 2 3 4 5

TIME (Months)

% ORIGINAL

CAPACITY

FIGURE 14.15 Effect of storage time / temperature on capacity of Li / SO

bat-

teries.

Voltage Delay. After extended long-term storage at elevated temperatures, the Li/SO

bat-

tery may exhibit a delay in reaching its normal operating voltage when placed on discharge,

especially at high current loads and low temperatures. This start-up or voltage delay is caused

by the protective ﬁlm formed on the lithium anode, the characteristic responsible for the

excellent shelf life of the cell. The speciﬁc delay time for a battery depends on such factors

as the history of the battery, the speciﬁc cell design and components, the storage time and

temperature, discharge load and temperature. Typically, the voltage delay is minimal or

nonexistent for discharges at moderate to low rates at temperatures above

⫺20⬚C. No delay

is evident on discharge at 20

⬚C, even after storage at 70⬚C for 1 year. On discharge at ⫺30⬚C,

the delay time is less than 200 ms after 8 weeks of storage at 70

⬚C on discharges lower than

the 40-h rate. At higher rates, the voltage delay increases with increasing storage temperature

and time. At the 2-h discharge rate, for example, the maximum start-up time is about

80 s after 8 weeks of storage at 70

⬚C; it is 7 s after 2 weeks of storage.

The start-up

voltage delay can be eliminated by preconditioning with a short discharge at a higher rate

to depassivate the anode until the operating voltage is reached since the delay will return

only after another extended storage period.

14.5.4 Cell and Battery Types and Sizes

The Li/SO

batteries are manufactured in a number of cylindrical cell sizes, ranging in

capacity to 35 Ah. Some of the cells are manufactured in standard ANSI cell sizes in

dimensions of popular conventional zinc primary batteries. While these single batteries may

be physically interchangeable, they are not electrically interchangeable because of the higher

cell voltage of the lithium cell (3.0 V for lithium, 1.5 V for the conventional zinc cells).

Table 14.9 lists some of the sizes and rated capacities of Li /SO

batteries that are currently

manufactured.

14.28

TABLE 14.9 Typical Lithium/ Sulfur Dioxide Cylindrical Cells (SAFT American, Inc.).*

Model

number Size

Nominal

capacity

(drain)

Maximum

recommended

continuous

current

Pulse

capability

Standard

operating

range Max. OD Max. H Weight

LO 34 SX 1 /3 R14

1/3C

0.86 Ah

(30 mA)

0.25 A 0.50 A ⫺60 /⫹70⬚C 25.6 mm 20.3 mm 16 g

LO 35 SX 2 /3 R14

2/3 C

2.00 Ah

(100 mA)

2.0 A 10 A

⫺60/ ⫹70⬚C 25.6 mm 35.9 mm 30 g

LO 26 SX R20

7.5 Ah

(240 mA)

3.0 A 10 A

⫺60/ ⫹70⬚C 33.8 mm 59.3 mm 85 g

LO 25 SX ‘‘Fat’’

8.00 Ah

(270 mA)

3.0 A 10 A

⫺60/ ⫹70⬚C 38.4 mm 50.3 mm 93 g

LO 52 SX 2 R20

16.0 Ah

(500 mA)

6.0 A 20 A

⫺60/ ⫹70⬚C 33.7 mm 115.6 mm 163 g

LO 38 SHX ‘‘long’’

1.50 Ah

(250 mA)

1.0 A 3.0 A

⫺60/ ⫹70⬚C 16.3 mm 57.2 mm 21 g

LO 29 SHX R14

3.50 Ah

(120 mA)

2.0 A 30 A

⫺60/ ⫹70⬚C 25.6 mm 50.4 mm 40 g

LO 43 SHX 5 / 4 R14

5/4 C

4.50 Ah

(500 mA)

2.0 A 30 A

⫺60/ ⫹70⬚C 25.6 mm 59.3 mm 53 g

LO 40 SHX 2 / 3 ‘‘Thin’’

3.50 Ah

(120 mA)

2.0 A 10 A

⫺60/ ⫹70⬚C 28.8 mm 41.6 mm 40 g

LO 30 SHX ‘‘Thin’’ D 5.75 Ah

(200 mA)

3.0 A 30 A

⫺60/ ⫹70⬚C 29.1 mm 59.8 mm 63 g

LO 26 SHX R20

7.20 Ah

(200 mA)

4.0 A 30 A

⫺60/ ⫹70⬚C 34.2 mm 59.8 mm 85 g

LO 39 SHX F 11.0 Ah

(200 mA)

8.0 A 60 A

⫺60/ ⫹70⬚C 30.7 mm 99.4 mm 125 g

* Pulse capability: 1 sec./ min pulses over 2.0 volts.

LITHIUM BATTERIES 14.29

14.5.5 Use and Handling of Li/ SO

Cells and Batteries—Safety

Considerations

The Li/ SO

battery is designed as a high-performance system and is capable of delivering

a high capacity at high discharge rates. The cell should not be physically or electrically

abused, safety features should not be bypassed, and manufacturers’ instructions should be

followed.

Abusive conditions could adversely affect the performance of the Li/SO

battery and

result in cell venting, rupture, explosion, or ﬁre. Preventative measures are discussed in Sec.

14.4.

The Li/ SO

battery is pressurized and contains materials that are toxic or ﬂammable.

Properly designed batteries are hermetically sealed so that there will be no leakage or out-

gassing, and they are equipped with safety vents which release if the batteries reach exces-

sively high temperatures and pressures, thus preventing an explosive condition.

The Li/SO

batteries can deliver very high currents. Because high internal temperatures

can develop from continuous high current drain and short circuit, batteries must be protected

by electrical fusing and thermal cutoffs. Charging of Li/ SO

batteries may result in venting,

rupture, or even explosion and should never be attempted. Cells or groups of cells connected

in parallel should be diode-protected to prevent one group from charging another. The bal-

anced Li /SO

cell is designed to handle forced discharges or cell reversal and will perform

safely within the speciﬁed bounds, but design limits should not be exceeded in any appli-

cation.

Proper battery design, using the Li/ SO

cell, should follow these guidelines:

1. Use electrical fusing and/ or current-limiting devices to prevent high currents or short-

circuits.

2. Protect with diodes if cells are paralleled or connected to a possible charging source.

3. Minimize heat buildup by adequate heat dissipation and protect with thermal cutoff de-

vices.

4. Do not inhibit cell vents in battery construction.

5. Do not use ﬂammable materials in the construction of batteries.

6. Allow for release of vented gases.

7. Incorporate resistor and switch to activate it to ensure complete depletion of active ma-

terials after normal discharge.

8. In certain cases, a diode is placed in parallel with the cell to limit the voltage excursion

in reversal.

Currently special procedures govern the transportation, shipment, and disposal of Li/SO

batteries as well as other lithium batteries.

12–15

Procedures for the use, storage, and handling

of these batteries also have been recommended. The latest issue of these regulations should

be consulted for the most recent procedures.

14.5.6 Applications

The desirable characteristics of the Li /SO

battery and its ability to deliver a high energy

output and operate over a wide range of temperatures, discharge loads, and storage conditions

have opened up applications for this primary battery that, heretofore, were beyond the ca-

pability of primary battery systems (see Sec. 6.4).

Major applications for the Li /SO

battery are in military equipment, such as radio trans-

ceivers and portable surveillance devices, taking advantage of its light weight and wide-

temperature operation. Table 14.10 lists the most common types of military Li/SO

batteries,

14.30

TABLE 14.10 U.S. Millitary Lithium/ Sulfur Dioxide Batteries (Per MIL-B-49430)

Battery type

Open circuit voltage

(series/ parallel)(V)

Nominal voltage

(series/ parallel)(V)

Nominal capacity

(series/ parallel)(Ah)

Weight

(g) Typical applications

Ba-5112/ U 12.0 11.2 1.8 180 Rescue radio/ beacon

BA-5567/U 3.0 2.6 0.8 20.0 Night vision equipment

BA-5599/U 9.0 7.2 7.2 454 Test equipment

Night vision equipment

BA-5600/U 9.0 8.4 7.2 363 Data terminals

BA-5800/U 6.0 5.6 7.2 220 Chemical agent monitors

Global positioning equipment

BA-5847/U 6.0 5.6 7.2 240 Test equipment

Antennas

Night vision equipment

BA-5598 15.0

(with 3.0 Volt tap)

14.0 8.0 631 Radios (PRC-77, PRC-25),

Scramblers

BA-5588 15.0 14.0 3.9 295 Handheld radios

Gas masks

BA-5557 30.0/ 15.0 26.0/13.0 2.25/ 4.5 500 Digital message device

BA-5590 30.0/ 15.0 24.0/12.0 7.2/ 14.4 1021 Radios (SINCGARS)

Satellite radios

Scramblers

Radar

Loudspeakers

UHF radios

Range ﬁnders

Counter measures

Weather instruments

Jammers

Cooling systems

LITHIUM BATTERIES 14.31

their characteristics and applications. Other military applications, such as sonobuoys and

munitions, have long shelf-life requirements, and the active Li /SO

primary battery can

replace reserve batteries used earlier. Some industrial applications have developed, particu-

larly to replace secondary batteries and eliminate the need for recharging. Consumer appli-

cations have been limited to date because of restrictions in shipment and transportation and

concern with its hazardous components.

14.6 LITHIUM/THIONYL CHLORIDE (Li/SOCl

) BATTERIES

The lithium/thionyl chloride (Li /SOCl

) battery has one of the highest cell voltages (nominal

voltage 3.6 V) and energy densities of the practical battery systems. Speciﬁc energy and

energy densities range up to about 590 Wh /kg and 1100 Wh /L, the highest values being

achieved with the low-rate batteries. Figures 7.8, 7.9, and 14.2 illustrate some of the advan-

tageous characteristics of the Li /SOCl

cell.

Li/ SOCl

batteries have been fabricated in a variety of sizes and designs, ranging from

wafer or coin cells with capacities as low as 400 mAh, cylindrical cells in bobbin and spirally

wound electrode structures, to large 10,000-Ah prismatic cells, plus a number of special sizes

and conﬁgurations to meet particular requirements. The thionyl chloride system originally

suffered from safety problems, especially on high-rate discharges and overdischarge, and a

voltage delay that was most evident on low-temperature discharges after high-temperature

storage.

Low-rate batteries have been used commercially for a number of years for memory backup

and other applications requiring a long operating life. The large prismatic batteries have been

used in military applications as an emergency back-up power source. Medium- and high-

rate batteries have also been developed as power sources for a variety of electric and elec-

tronic devices. Some of these batteries contain additives to the thionyl chloride and other

oxyhalide electrolytes to enhance certain performance characteristics. These are covered in

Sec. 14.7.

14.6.1 Chemistry

The Li /SOCl

cell consists of a lithium anode, a porous carbon cathode, and a nonaqueous

SOCl

:LiAlCl

electrolyte. Other electrolyte salts, such as LiGaCl

have been employed for

specialized applications. Thionyl chloride is both the electrolyte solvent and the active cath-

ode material. There are considerable differences in electrolyte formulations and electrode

characteristics. The proportions of anode, cathode, and thionyl chloride will vary depending

on the manufacturer and the desired performance characteristics. Signiﬁcant controversy

exists as to the relative safety of anode-limited vs. cathode-limited designs.

Some cells

have one or more electrolyte additives. Catalysts, metallic powders, or other substances have

been used in the carbon cathode or in the electrolyte to enhance performance.

The generally accepted overall reaction mechanism

4Li

⫹ 2SOCl → 4LiCl ↓ ⫹ S ⫹ SO

The sulfur and sulfur dioxide are initially soluble in the excess thionyl chloride electrolyte,

and there is a moderate buildup of pressure due to the generation of sulfur dioxide during

the discharge. The lithium chloride, however, is not soluble and precipitates within the porous

carbon black cathode as it is formed. Sulfur may precipitate in the cathode at the end of

discharge. In most cell designs and discharge conditions, this blocking of the cathode is the

factor that limits the cell’s service or capacity. Formation of sulfur as a discharge product

can also present a problem because of a possible reaction with lithium which may result in

a thermal runaway condition.

14.32 CHAPTER FOURTEEN

TABLE 14.11 Characteristics of Typical High-Capacity and Wafer-Type Cylindrical Bobbin-Type Li / SOCl

Batteries

–

AA C

–

Rated capacity at C /1000 rate, Ah 1.20 1.65 2.40 8.5 1.7 19.0

Dimensions (max)

Diameter, mm 14.5 14.5 14.5 26.2 32.9 32.9

Height, mm 25.2 33.5 50.5 50 10.0 61.5

Volume, cm

4.16 5.53 8.34 27.0 8.50 52.3

Weight, g 9.2 11.8 17.6 50.5 21.5 92.5

Maximum current for continuous

use, mA

50 75 100 230 230

Speciﬁc Energy Wh/ kg 456 490 475 590 275 720

Energy Density Wh/ L 1010 1045 1010 1100 700 1270

Source: Tadiran, Ltd.

The lithium anode is protected by reacting with the thionyl chloride electrolyte during

stand forming a protective LiCl ﬁlm on the anode as soon as it contacts the electrolyte. This

passivating ﬁlm, while contributing to the excellent shelf life of the cell, can cause a voltage

delay at the start of a discharge, particularly on low-temperature discharges after long stands

at elevated temperatures. The presence of trace qualities of moisture leads to the formation

of HCl which increases passivation, as does the presence of ppm levels of iron. Some prod-

ucts have special anode treatments or electrolyte additives to overcome or lower this voltage

delay.

The low freezing point of thionylchloride (below

⫺110⬚C) and its relatively high boiling

point (78.8⬚C) enable the cell to operate over a wide range of temperature. The electrical

conductivity of the electrolyte decreases only slightly with decreasing temperature. Some of

the components of the Li /SOCl

systems are toxic and ﬂammable; thus exposure to open or

vented cells or cell components should be avoided.

14.6.2 Bobbin-Type Cylindrical Batteries

Li/ SOCl

bobbin batteries are manufactured in a cylindrical conﬁguration, some in sizes

conforming to ANSI standards. These batteries are designed for low- to moderate-rate dis-

charge and are not typically subjected to continuous discharge at rates higher than the

C/ 100 rate. They have a high energy density. For example, the D-size cell delivers 19.0-Ah

at 3.5 V, compared with 15 Ah at 1.5 V for the conventional zinc-alkaline cells (see Tables

7.5 and 14.11).

Construction. Figure 14.16 shows the constructional features of the cylindrical Li/SOCl

cell, which is built as a bobbin-type construction. The anode is made of lithium foil which

is swaged against the inner wall of a stainless or nickel-plated steel can; the separator is

made of nonwoven glass ﬁbers. The cylindrical, highly porous cathode, which takes up most

of the cell volume, is made of Teﬂon-bonded acetylene black. The cathode also incorporates

a current collector which is a metal cylinder in the case of the larger cells and a pin in the

case of smaller cells which do not have an annular cavity.

LITHIUM BATTERIES 14.33

FIGURE 14.16 Cross section of bobbin-type Li / SOCl

battery.

(From Ref. 23.)

Performance. The open-circuit voltage of the Li /SOCl

cell is 3.65 V; typical operating

voltages range between 3.3 and 3.6 V with an end voltage of 3.0 V. Typical discharge curves

for the Li/SOCl

battery are shown in Fig. 14.17a for the D-size cell. The Li /SOCl

cell

discharges are characterized by a ﬂat proﬁle with good performance over a wide range of

temperatures and low- to moderate-rate discharges. Figure 14.17b shows the operating volt-

age of the bobbin D-cell at various drain rates and temperatures. The relationship of capacity

with current is given in Fig. 14.18, showing the performance from

⫺30 to 72⬚C. The Li/

SOCl

cell is capable of performance at unusually high temperatures. At 145⬚C, (Fig. 14.19)

the cells deliver most of their capacity at high rates and up to 70% at low discharge rates

(20 days of discharge).

Li/ SOCl

cells are used to build battery packs that are employed

in oil exploration and most withstand temperatures to 150

⬚C as well as high levels of shock

and vibration.

Figure 14.20 shows the behavior of AA cells on continuous low-rate discharge at 25

⬚C.

The discharge curve is very ﬂat at these low-current drains, but capacity loss below the 2.4

Ah rating occurs below the 1000-hour rate due to parasitic self-discharge.

The capacity or service life of the high-capacity bobbin-type Li/SOCl

cell, normalized

for a 1-kg and 1-L size cell, at various discharge temperatures and loads, is summarized in

Fig. 14.21.

The long shelf life of the Li /SOCl

battery is due to the stability of the lithium anode in

contact with the electrolyte, as a result of a protective LiCl ﬁlm that forms on the lithium

surface. The long shelf life can also be attributed to the stability of other cell components.

For example, the can and cover are cathodically protected by the lithium, and the carbon,

stainless-steel collector, and glass separator are all inert in the electrolyte. Figure 14.22 shows

the loss of capacity after 3 years at 20

⬚C, a loss of about 1 to 2% per year. Storage at 70⬚C

results in a capacity loss of about 5% per year. Cells should preferably be stored in an

upright position; storage on the side or upside down may result in higher capacity loss.

14.34 CHAPTER FOURTEEN

DISCHARGE CHARACTERISTICS @ + 25 C

Volts

56.2 Ω

60 mA

(10.0 Ah)

698 Ω

5 m A

(19.0 Ah)

2.0 KΩ

1.8 mA

(18.5 AH)

5.9 KΩ

0.6 mA

(18.5 Ah)

18.2 KΩ

200 µA

(16.6 Ah)

10 100 1000 10000 100000

Hours

4.0

3.5

3.0

2.5

2.0

1.5

1.0

(a)

VOLTAGE VS. TEMPERATURE

Temperature

Volts

-50 -30 -10 10 30 50 70 90

3.7

3.6

3.5

3.4

3.3

3.2

3.1

3.0

2.9

0.2mA

2mA

6mA

10mA

20mA

60mA

(b)

FIGURE 14.17 (a) Discharge characteristics of high-capacity Li / SOCl

cylindrical

D-size bobbin battery at ⫹25⬚C. (b) Operating (plateau) voltage of the same battery

as a function of temperature at various drain rates. (Ref. 23.)