Lithium Batteries

Description

The term "lithium battery" refers to a family of different chemistries, comprising many types of cathodes and electrolytes. The battery requires from 0.15 to 0.3 kg of lithium per kWh.

The most common type of lithium cell used in consumer applications uses metallic lithium as anode and manganese dioxide as cathode, with a salt of lithium dissolved in an organic solvent.

Another type of lithium cell having a large energy density is the lithium-thionyl chloride cell. Invented by Adam Heller, Lithium-thionyl chloride batteries are generally not sold to the consumer market, and find more use in commercial/industrial applications, or are installed into devices where the consumer does not replace them.  The cell contains a liquid mixture of thionyl chloride (SOCl₂) and lithium tetrachloroaluminate (LiAlCl
4), which act as the cathode and electrolyte, respectively. A porous carbon material serves as a cathode current collector which receives electrons from the external circuit. Lithium-thionyl chloride batteries are well suited to extremely low-current applications where long life is necessary, such as wireless alarm systems.

Applications

Lithium batteries find application in many long-life, critical devices, such as pacemakers and other implantable electronic medical devices. These devices use specialized lithium-iodide batteries designed to last 15 or more years. But for other, less critical applications such as in toys, the lithium battery may actually outlast the device. In such cases, an expensive lithium battery may not be cost-effective.

Lithium batteries can be used in place of ordinary alkaline cells in many devices, such as clocks and cameras. Although they are more costly, lithium cells will provide much longer life, thereby minimizing battery replacement. However, attention must be given to the higher voltage developed by the lithium cells before using them as a drop-in replacement in devices that normally use ordinary zinc cells.

Lithium batteries also prove valuable in oceanographic applications. While lithium battery packs are considerably more expensive than standard oceanographic packs, they hold up to three times the capacity of alkaline packs. The high cost of servicing remote oceanographic instrumentation (usually by ships) often justifies this higher cost.