Primary Lithium Cells
Characteristics
Lithium is the lightest of metals and it floats on water. It also has the greatest electrochemical potential which makes it one of the most reactive of metals. These properties give Lithium the potential to achieve very high energy and power densities permitting batteries with very long useful life and small cell packages.
Because lithium reacts violently with water, as well as nitrogen in air, this requires sealed cells. High-rate lithium cells build up temperature and pressure if they are short circuited or abused. Thus, the cell design needs to include safety vents, which release the pressure or rupture to prevent uncontrolled explosion.
Typical chemistries are lithium manganese dioxide, lithium sulphur dioxide and lithium thionyl chloride (see below) but other variants are available.
Available cell voltages range between 3 and 4 Volts
Cell packaging includes coin cell and cylindrical packages.
Thin film cells based on ceramic or flexible substrates are also available.
Advantages
High energy density, double that of premium alkaline batteries
Low weight
High cell voltage
Flat discharge characteristic
Low self discharge Very long shelf life
Very long operating life (15 to 20 years for lithium thionyl chloride)
Wide operating temperature range (
-60 ° C to +85 ° C for lithium sulfur dioxide)
Excellent durability
Small cell size
Shortcomings
High cost
Applications
Computer memory protection
Medical implants
Heart pacemakers
Defibrillators
Utility meters
Watches
Cameras
Calculators
Car keys
Security transmitters
Smoke alarms
Aerospace applications
Because of its superior performance characteristics Lithium technology is replacing
older, traditional technologies in an ever widening range of applications.
Costs
More expensive than common consumer primary Leclanché and alkaline batteries
Lithium-Manganese Dioxide Cell: anode: lithium foil cathode: manganese dioxide electrolyte: separator sheet impregnated with electrolytic salts cell voltage: 3 volts The most common non-rechargeable lithium cell.
Lithium Iron Disulphide Cell: anode: lithium foil cathode: iron disulfide with aluminium cathode contact electrolyte: separator sheet impregnated with electrolytic salts. Designed to be a drop in replacement for zinc carbon or alkaline batteries the cell voltage: 1.5 volts. Often called the "Voltage compatible" lithium cell, they have a higher energy density than the cells they replace and tailored to high current applications.
Lithium Thionyl Chloride Cell: The highest energy density of all Lithium type cells have a service life of 15 to 20 years.
Lithium Iodine Cell: Provides excellent safety and long life. Uses only solid components and the separator is self healing if cracks occur. High internal impedance limits its use to low drain applications. Used for the majority of implanted cardiac pacemakers.
See note on the Toxicity of Lithium |
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