Lithium Primary 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 Llithium 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, Llithium Sulphur dioxide, Lithium Thionyl Chloride (see below) and Lithium Oxygen (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.

Lithium Air Cell

Similar to Zinc Air cells they have a very high theoretical energy density. The anode, a metallic Lithium foil pressed into a nickel mesh current collector, is electrochemically coupled to an unlimited supply of atmospheric Oxygen through an air cathode. The air cathode is a layered electrode with two Carbon layers containing catalysts, such as Manganese, separated by a Nickel mesh current collector. A PTFE Teflon membrane is used to repel water from the atmosphere while still allowing Oxygen diffusion. Non-aqueous electrolytes such as LiPF₆ must be used due to Lithium interaction with water

The cell voltage is 3.0 Volts and the storage capacity is limited by the Lithium anode. The cell has a flat discharge curve and a long storage life.

Performance varies widely wih temperature.

Rechargeable versions are also possible.

See note on the Toxicity of Lithium