Raw materials in battery technology: Lead (Glossary)

Lead is a blueish-grey, very soft and ductile heavy metal. Is is stable in air since it protects itself with a coat of lead oxide. Lead is attacked by water in the presence of oxygen and produces the insoluble lead hydroxide Pb(OH)₂, if hard water is used it produces the insoluble lead carbonate PbCO₃. In soft water and the simultaneous presence of ample carbon dioxide, the soluble lead hydrogen carbonate is formed Pb(HCO₃)₂; lead is this unstable in this constellation. Lead is not attacked by cold sulphuric or hydrochloric acid since a hardly soluble surface coating of lead sulphate PbSO₄ or lead chloride PbCl₂ forms immediately. It is, on the other hand, dissolved by oxidising acids.

The world-wide production of lead in 2000 was almost 3.5 million tons, the lead reserves were estimated at 200 million tons. Over 60% of the world's demand for lead is accounted for by starter batteries, whereby the recycling rate in Germany is approx. 90%. Other fields of application for lead include cable sheaths or lead linings and protection against sulphuric acid and radiation.

Lead (absorbed, for example, in the form of fine dusts or vapours, including through the skin) and lead compounds are toxic. Lead poisoning (plumbism, saturnism) is an occupational disease that must be reported.

In battery technology lead is primarily used for the plates in Lead accumulators, commonly as lead-antimony or lead-calcium-tin alloys. The reactions that occur at the electrodes are essentially the oxidisation of lead (anode) and the reduction of lead oxide (cathode) to lead sulphate (PbSO₄). The Electrolyte used is Sulphuric acid. A special feature of lead accumulators is that both electrodes are made of the same base materials and the product of the discharge reaction is also the same at both electrodes.

Some key technical data

Chemical symbol: Pb

Atomic number: 82

Relative atomic mass: 207.2

Oxidation numbers: +4, +2

Density: 11.34 g/cm³

Melting point: 327°C

Boiling point: 1,749°C

Specific electrical resistance: 21

	See also:
		Glossary overview Lead accumulators (Glossary) Lead price (day chart)

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