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Engineering LibreTexts

6.4: Primary batteries

  • Page ID
    7817
  • 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
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