Raw materials in battery technology: Mercury (Glossary)

Mercury is a silvery-white heavy metal, apart from bromine the only element that is liquid at room temperature. Below 300°C it is quite resistant to air, nor is it attacked by water, hydrochloric acid or diluted Sulphuric acid. Concentrated sulphuric and nitric acid as well as nitrohydrochloric acid, on the other hand, dissolve the metal.

Mercury only occurs in nature in small amounts in its native form. It is extracted as cinnabarite (mercury oxide), for example in south Spain and in the Toscana. The global production is around 3,000 tons per year.

Mercury is very toxic (mercurialism), particularly its vapours (toxic amount 0.1mg/m³) and several of its compounds. Since each ton of coal contains around 1 gram of mercury, several thousands of tons of mercury enter the atmosphere and thus the biological cycle alone through the combustion of coal.

The majority of mercury that is produced is used to make its compounds and alloys (amalgams). In its elementary form it has been largely replaced by less toxic materials.

As long ago as 1886 there was a variant of the Lalande-Chaperon-Cell that used a mercury cathode. The principle was rediscovered in the 50ies and mercury was used particularly in mercury-zinc batteries (button cells for watches in the 70ies) as a cathodic oxidation agent. In shares of up to 1%, however, it was also used in early carbon-zinc and alkali-manganese batteries to prevent gassing. Because of its toxicity mercury is only used today in a few special batteries.

See also: Ban on cadmium and mercury

Some key technical data

Chemical symbol: Hg

Atomic number: 80

Relative atomic mass: 200.59

Oxidation numbers: +2, +1

Density: 21.45 g/cm³

Melting point: -39°C

Boiling point: 357°C

Specific electrical resistance: 96

	See also:
		Glossary overview Ban on cadmium and mercury

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