Lead–acid batteries, invented in 1859 by French physicist Gaston Planté

Gaston Planté

Gaston Planté was the French physicist who invented the lead-acid battery in 1859. The lead-acid battery eventually became the first rechargeable electric battery marketed for commercial use.Planté was born on April 22, 1834, in Orthez, France...

, are the oldest type of rechargeable battery

Rechargeable battery

A rechargeable battery or storage battery is a group of one or more electrochemical cells. They are known as secondary cells because their electrochemical reactions are electrically reversible. Rechargeable batteries come in many different shapes and sizes, ranging anything from a button cell to...

. Despite having a very low energy-to-weight ratio and a low energy-to-volume ratio, their ability to supply high surge currents means that the cells maintain a relatively large power-to-weight ratio

Power-to-weight ratio

Power-to-weight ratio is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measurement of actual performance of any engine or power sources...

. These features, along with their low cost, make them attractive for use in motor vehicles to provide the high current required by automobile starter motors

Automobile self starter

A starter motor is an electric motor for rotating an internal-combustion engine so as to initiate the engine's operation under its own power.- History :...

.

Lead–acid batteries (under 5 kg) account for 1.5% of all portable secondary battery sales in Japan by number of units sold (25% by price).

Sealed lead–acid batteries accounted for 10% by weight of all portable battery sales in the EU in 2000.

In the charged state, each cell contains negative electrodes of elemental lead (Pb) and positive electrodes of lead(IV) oxide  in an electrolyte

Electrolyte

In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

 of approximately 33.5% v/v (4.2 Molar) sulfuric acid

Sulfuric acid

Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 .

In the discharged state both the positive and negative become lead(II) sulfate

Lead(II) sulfate

Lead sulfate is a white crystal or powder. It is also known as fast white, milk white, sulfuric acid lead salt or anglesite....

  and the electrolyte

Electrolyte

In chemistry, an electrolyte is any substance containing free ions that make the substance electrically conductive. The most typical electrolyte is an ionic solution, but molten electrolytes and solid electrolytes are also possible....

 loses much of its dissolved sulfuric acid

Sulfuric acid

Sulfuric acid is a strong mineral acid with the molecular formula . Its historical name is oil of vitriol. Pure sulfuric acid is a highly corrosive, colorless, viscous liquid. The salts of sulfuric acid are called sulfates...

 and becomes primarily water.