Voltaic pile
The first battery to provide continuous electric current.
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The first device capable of delivering a steady electric current to a circuit was the voltaic pile, invented by Italian chemist Alessandro Volta and described in his 1799 publication. His design stacked alternating discs of copper (or silver) and zinc, separated by cloth or cardboard soaked in brine, which served as the electrolyte. Connecting the top and bottom contacts with a wire allowed current to flow through both the pile and the wire. Volta’s invention grew out of a dispute with fellow Italian scientist Luigi Galvani, who had earlier observed that a circuit made of two metals and a frog’s leg could make the leg twitch.
Applications
By 1794, Volta had shown that a similar circuit using brine-soaked cloth instead of a frog’s leg also produced an electric current. The pile’s ability to generate continuous charge made it the first true battery. This breakthrough quickly led to other discoveries: in 1800, William Nicholson and Anthony Carlisle used it to electrolyze water into oxygen and hydrogen, and Humphry Davy later isolated or discovered the elements sodium, potassium, calcium, boron, barium, strontium, and magnesium (all between 1807 and 1808). Until the dynamo arrived in the 1870s, the entire 19th-century electrical industry relied on batteries derived from Volta’s design, such as the Daniell cell and Grove cell.
Electrochemistry
Volta’s original piles included an extra zinc disc at the bottom and an extra copper disc at the top, which were later found to be unnecessary. He believed the electromotive force (emf) that drove the current came from contact between the two metals, not from the electrolyte. Chemists soon realized, however, that water in the brine participated in chemical reactions, producing hydrogen gas at the copper or silver electrode.
Modern understanding explains that when the cell supplies current, zinc at the anode oxidizes, dissolving into the electrolyte as Zn²⁺ ions and leaving behind two electrons. Michael Faraday, building on Volta’s work and the electromagnetism studies of his mentor Humphry Davy, used both magnets and the pile in his experiments. Faraday argued that all forms of electricity—voltaic, magnetic, thermal, and animal—were identical, and his efforts to prove this led to two laws of electrochemistry that contradicted Volta’s earlier theories.
Quick Facts
- Inventor
- Alessandro Volta
- Year of invention
- 1799
- Voltage per cell
- 0.76 V (with brine electrolyte)
- Electrode materials
- copper (or silver) and zinc
- Electrolyte
- brine (salt water) soaked into cloth or cardboard
Facts from the source article.
Lore & Background
Volta's invention was built on Luigi Galvani's 1780s discovery that a circuit of two metals and a frog's leg can cause the frog's leg to respond. Volta demonstrated in 1794 that when two metals and brine-soaked cloth or cardboard are arranged in a circuit they too produce an electric current. In 1800, Volta stacked several pairs of alternating copper (or silver) and zinc discs separated by cloth or cardboard soaked in brine, which increased the total electromotive force. This was the first 'true' battery, giving off continuous charge.
Because Volta believed that the electromotive force occurred at the contact between the two metals, his piles had a different design than the modern design. His piles had one extra disc of copper at the top, in contact with the zinc, and one extra disc of zinc at the bottom, in contact with the copper. These extra discs were later shown to be unnecessary. Many scientific instruments that belonged to Alessandro Volta are preserved in the University History Museum of the University of Pavia, where Volta taught from 1778 to 1819; the piles on display are not original, as the ones preserved in Pavia were lent on the occasion of the centenary of the invention and subsequently lost in a fire.
A number of high-voltage dry piles were invented between 1800 and the 1830s in an attempt to determine the source of electricity of the wet voltaic pile, and specifically to support Volta's hypothesis of contact tension. Volta himself experimented with a pile whose cardboard discs had dried out, most likely accidentally. The first to publish the discovery of a dry pile that produced a current was Johann Wilhelm Ritter in 1802. One form of dry pile is the Zamboni pile.
Reader's Guide
The voltaic pile enabled a rapid series of other discoveries, including the electrical decomposition (electrolysis) of water into oxygen and hydrogen by William Nicholson and Anthony Carlisle (1800), and the discovery or isolation of the chemical elements sodium (1807), potassium (1807), calcium (1808), boron (1808), barium (1808), strontium (1808), and magnesium (1808) by Humphry Davy. The entire 19th-century electrical industry was powered by batteries related to Volta's (e.g. the Daniell cell and Grove cell) until the advent of the dynamo (the electrical generator) in the 1870s.
On 20 March 1800, Alessandro Volta wrote to the London Royal Society to describe the technique for producing electric current using his device. On learning of the voltaic pile, Nicholson and Carlisle used it to discover the electrolysis of water. Humphry Davy showed that the electromotive force was caused by a chemical reaction, not by the voltage difference between the two metals.
He also used the voltaic pile to decompose chemicals and to produce new chemicals. William Hyde Wollaston showed that electricity from voltaic piles had identical effects to those of electricity produced by friction. In 1802 Vasily Petrov used voltaic piles in the discovery and research of electric arc effects.
Expanding on Volta's work and the electro-magnetism work of his mentor Humphry Davy, Michael Faraday utilized both magnets and the voltaic pile in his experiments with electricity. Faraday believed that all 'electricities' being studied at the time (voltaic, magnetic, thermal, and animal) were one and the same.
His work to prove this theory led him to propose two laws of electrochemistry which stood in direct conflict with the current scientific beliefs of the day as laid down by Volta thirty years earlier. Because of their contributions to the understanding of this field of study, Faraday and Volta are both considered to be among the fathers of electrochemistry. The words 'electrode' and 'electrolyte' are due to Faraday.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Voltaic pile (CC BY-SA 4.0).
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