Lithium battery


 * Lithium batteries are not to be confused with lithium-ion batteries which are high energy-density rechargeable batteries

Lithium batteries are primary batteries that have lithium metal or lithium compounds as an anode. Depending on the design and chemical compounds used, lithium cells can produce voltages from 1.5 V to about 3.0 V, twice the voltage of an ordinary zinc-carbon battery or alkaline cell. Lithium batteries are used in many portable consumer electronic devices, and are widely used in industry.

Description
The term "lithium battery" refers to a family of different chemistries, comprising many types of cathodes and electrolytes. One type of lithium cell having a large energy density is the lithium-thionyl chloride cell. In this cell, a liquid mixture of thionyl chloride (SOCl2) and lithium tetrachloroaluminate (LiAlCl4) acts as the cathode and electrolyte respectively. A porous carbon material serves as a cathode current collector which receives electrons from the external circuit. However, 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 no consumer replacement is performed. Lithium-thionyl chloride batteries are well suited to extremely low-current applications where long life is necessary, e.g. wireless alarm systems.

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.

[[Image:Photo-lithium-cell-disassembled.jpg|thumb|center|400px|Disassembled CR2016 battery

1st: Anode cup, upside down, spent lithium partially scratched off

2nd: Separator, a thin layer of porous material soaked with electrolyte - lithium salt in an organic solvent

3rd: Cathode, a tablet of manganese dioxide

4th: Cathode can, with current collector (carbon layer) on its bottom and a gasket around its inner edge. Damaged by clumsy opening attempt.]]

Chemistries
The liquid organic electrolyte is usually a solution of an ion-forming inorganic lithium compound in a mixture of a high-permittivity solvent (eg. propylene carbonate) and a low-viscosity solvent (eg. dimethoxyethane).

Applications
Lithium batteries find application in many long-life, critical devices, such as artificial 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 toy. In such cases, an expensive lithium battery is not cost-efficient.

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 cells.

Small lithium batteries are very commonly used in small, portable electronic devices, such as PDAs, watches, thermometers, and calculators, as backup batteries in computers and communication equipment, and in remote car locks. They are available in many shapes and sizes, with a common variety being the 3 volt "coin" type manganese variety, typically 20 mm in diameter and 1.6–4 mm thick. The heavy electrical demands of many of these devices make lithium batteries a particularly attractive option. In particular, lithium batteries can easily support the brief, heavy current demands of devices such as digital cameras, and they maintain a higher voltage for a longer period than alkaline cells.

Some other lithium batteries use a platinum-iridium alloy instead of more usual compounds. These batteries are generally not preferred, as their cost is high and they tend to be fragile.

Air Travel
The United States Transportation Security Administration announced restrictions effective January 1, 2008 on lithium batteries in checked and carry-on luggage. The rules forbid lithium batteries not installed in a device from checked luggage and restrict them in carry-on luggage by total lithium content.

Rapid-discharge issues
Lithium batteries can provide extremely high currents and can discharge very rapidly when short-circuited. Although this is useful in applications where high currents are required, a too-rapid discharge of a lithium battery can result in overheating of the battery, rupture, and even explosion. Lithium-thionyl chloride batteries are particularly capable of this type of discharge. Consumer batteries usually incorporate overcurrent or thermal protection or vents in order to prevent explosion.

Because of the above risks, shipping and carriage of lithium batteries is restricted in some situations, particularly transport of lithium batteries by air.

The computer industry's drive to increase battery capacity can test the limits of sensitive components such as the membrane separator, a polyethylene or polypropylene film that is only 20-25 µm thick. The energy density of lithium-ion batteries has more than doubled since they were introduced in 1991. When the battery is made to contain more material, the separator can undergo stress.

Lithium batteries and methamphetamine labs
Unused lithium batteries provide a convenient source of lithium metal for use as a reducing agent in illegal methamphetamine labs. Some jurisdictions have passed laws to restrict lithium battery sales or asked businesses to make voluntary restrictions in an attempt to help curb the creation of illegal meth labs. For example a newspaper article from January 2004 reports that Wal-Mart stores limit the sale of disposable lithium batteries to three packages in Missouri and four packages in other states. However, the heavy demand for lithium batteries for use in modern, current-hungry devices such as digital cameras conflicts with such restrictions.