Batteries

Strictly, a battery is a collection of multiple electrochemical cells, but in popular usage battery often refers to a single cell.The first electrochemical cell was developed by thephysicist Alessandro Volta in 1792, and in 1800 he invented the first battery — for him, a “pile” of cells.

The usage of “battery” to describe electrical devices dates to, who in 1748 described multiple (early electrical) by analogy to aThus Franklin’s usage to describe multiple Leyden jars predated Volta’s use of multiple galvanic cells. . It is speculated, but not established, that several ancient artifacts consisting of copper sheets and iron bars, and known as may have been galvanic cells.

Volta’s work was stimulated by the Italian anatomist and physiologist , who in 1780 noticed that dissected frog’s legs would twitch when struck by a spark from a , an external source of electricity.In 1786 he noticed that twitching would occur during lightning storms.After many years Galvani learned how to produce twitching without using any external source of electricity. In 1791 he published a report on “animal electricity.”He created an electric circuit consisting of the frog’s leg (FL) and two different metals A and B, each metal touching the frog’s leg and each other, thus producing the circuit A-FL-B-A-FL-B…etc. In modern terms, the frog’s leg served as both the and the , and the metals served as . He noticed that even though the frog was dead, its legs would twitch when he touched them with the metals.

Within a year, Volta realized the frog’s moist tissues could be replaced by cardboard soaked in salt water, and the frog’s muscular response could be replaced by another form of electrical detection. He already had studied the electrostatic phenomenon of which required measurements of electric charge and of electrical potential (“tension”). Building on this experience, Volta was able to detect electric current through his system, also called a . The terminal voltage of a cell that is not discharging is called its(emf), and has the same unit as electrical potential, named ( and measured in, in honor of Volta. In 1800, Volta invented the battery by placing many voltaic cells in , literally piling them one above the other. This voltaic pile gave a greatly enhanced net emf for the combination, with a voltage of about 50 volts for a 32-cell pile.In many parts of Europe batteries continue to be called piles.

Volta did not appreciate that the voltage was due to chemical reactions. He thought that his cells were an inexhaustible source of energy,and that the associated chemical effects (e.g. corrosion) were a mere nuisance, rather than an unavoidable consequence of their operation, as showed in 1834. According to Faraday,(positively charged ions) are attracted to theandnegatively charged ions) are attracted to the

Although early batteries were of great value for experimental purposes, in practice their voltages fluctuated and they could not provide a large current for a sustained period. Later, starting with the , batteries provided more reliable currents and were adopted by industry for use in stationary devices, particularly in telegraph networks where they were the only practical source of electricity, since electrical distribution networks did not exist at the time.These wet cells used liquid electrolytes, which were prone to leakage and spillage if not handled correctly. Many used glass jars to hold their components, which made them fragile. These characteristics made wet cells unsuitable for portable appliances. Near the end of the nineteenth century, the invention of , which replaced the liquid electrolyte with a paste, made portable electrical devices practical.

Since then, batteries have gained popularity as they became portable and useful for a variety of purposes.

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