6.4: Primary batteries
- Page ID
- 7817
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Primary batteries are not easily rechargeable, and consequently are discharged then disposed of. Many of these are “dry cells” – cells in which the electrolyte is not a liquid but a paste or similar. The cell electrochemical reactions are not easily reversible and cell is operated until the active components in the electrodes are exhausted. Generally primary batteries have a higher capacity and initial voltage than rechargeable batteries.
Applications:
- Portable devices
- Lighting
- Toys
- Memory back-up
- Watches/clocks
- Hearing aids
- Radios
- Medical implants
- Defence related systems such as missiles
Advantages:
- Inexpensive
- Convenient
- Lightweight
- Good shelf life
- High Energy density at low/moderate discharges
Disadvantages:
- Can only be used once
- Leads to large amount of waste batteries to be recycled
- Batteries put into landfill sites have severe environmental impact
- Life cycle energy efficiency < 2 %
The table below demonstrates the properties of various primary batteries:
| System | Nominal Cell Voltage (V) | Capacity (Wh/kg) | Advantages | Disadvantages | Applications |
|---|---|---|---|---|---|
|
1.50
|
65
|
Lowest cost; variety of shapes and sizes
|
Low energy density; poor low-temperature performance
|
Torches; radios; electronic toys and games
|
|
|
Mg/MnO2
|
1.60
|
105
|
Higher capacity than C/Zn; good shelf life
|
High gassing on discharge; delayed voltage
|
Military and aircraft receiver-transmitters
|
|
1.50
|
95
|
Higher capacity than C/Zn; good low-temperature performance
|
Moderate cost
|
Personal stereos; calculators; radio; TV
|
|
|
Zn/HgO
|
1.35
|
105
|
High Energy density; flat discharge; stable voltage
|
Expensive; energy density only moderate
|
Hearing aids; pacemakers; photography; military sensors/detectors
|
|
Cd/HgO
|
0.90
|
45
|
Good high and low-temperature performance; good shelf life
|
Expensive; low energy density
|
|
|
1.50
|
130
|
High Energy density, good high rate performance
|
Expensive (but cost effective)
|
Watches; photography; missiles; Larger space applications
|
|
|
Zn/Air
|
1.50
|
290
|
High Energy density; long shelf life
|
Dependent on environment; limited power output
|
Watches; hearing aids; railway signals; electric fences
|
|
Li/SOCl2
|
3.60
|
300
|
High Energy density; long shelf life
|
Only low to moderate rate applications
|
Memory devices; standby electrical power devices
|
|
Li/SO2
|
3.00
|
280
|
High energy density; best low-temperature performance; long shelf life
|
High-cost pressurized system
|
Military and special industrial needs
|
|
Li/MnO2
|
3.00
|
200
|
High energy density; good low-temperature performance; cost effective
|
Small in size, only low-drain applications
|
Electrical medical devices; memory circuits; fusing
|