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A Galvanic Cell is an electrochemical cell that stores chemical Energy and makes it available in an electrical form, and a battery is a string of two or more cells in series. Other types of electrochemical cells include Electrolytic Cell s, Fuel Cell s, Flow Cells , or Voltaic Cell s.1 Though an early form of battery may have been used in antiquity (the Baghdad Battery ), the development of modern batteries started with the Voltaic Pile , invented by the Italian physicist Alessandro Volta in 1800. Banks, Sir Joseph (1800), "On the Electricity excited by the mere Contact of conducting Substances of different Kinds. In a Letter from Mr. Alessandro Volta, F.R.S., Professor of Natural Philosophy at the University of Pavia, to the Rt. Hon. Sir. Joseph Banks, Bart. K.B. P.R.S. Read June 26, 1800." ''Philosophical Transactions of the Royal Society of London,'' 1800, p. 403 {Link without Title} . The paper was submitted in April 1800 and read before the Royal Society on June 26, 1800: 2, p. 261 . Some sources identify the year of ''invention'' as 1799; e.g. "The voltaic pile... was constructed by Volta in 1799, and became known in England in 1800," 3, p. 30 The publication in 1800 "caused a sensation" according to 4 p. 72 According to a 2005 estimate, the worldwide battery industry generates US$ 48 Billion in sales annually.5 Power Shift: DFJ on the lookout for more power source investments . Accessed 20 November 2005]. Formally, an electrical "battery" is a series-connected array of similar ''voltaic cells'' ("cells"). However, in many contexts it is common to call a single cell a ''battery''.Battery" (def. 6), ''The Random House Dictionary of the English Language, the Unabridged Edition (2nd edition)'', 1996 ed. The two types of batteries, Primary and Secondary , both convert chemical energy to electrical energy. However, primary batteries can only be used once, as they use up their chemicals in an irreversible reaction. Secondary batteries can be recharged because the chemical reactions they use are Reversible ; they are recharged by running a current parallel to the battery, with an orientation opposite to the original discharge. Battery - Background, Primary cells, Secondary cells - Net Industries Science Encyclopedia . Retrieved 26 August 2007. HISTORY See Also: History of the battery The earliest known artifacts that may have served as batteries are the Baghdad Batteries , which existed some time between 250 BC and 640 AD . However, it is not known what electrical function they may have served, and if they were in fact batteries at all. Scientists have developed several theories about its use, including Medicine (as a Painkiller ) and Electroplating jewelry. World Mysteries - Strange Artifacts, Baghdad Battery . Retrieved 16 March 2007. The story of the modern battery begins in the 1780s with the discovery of "animal electricity" by Luigi Galvani , which he published in 1791 .Saslow, Ch. 8, p. 337. He created an Electric Circuit consisting of two different metals, with one touching a frog's leg and the other touching both the leg and the first metal, thus closing the circuit. In modern terms, the frog's leg served as both Electrolyte and Detector , and the metals served as Electrode s. He noticed that even though the frog was dead, its legs would twitch when he touched them with the metals. Luigi Galvani - Corrosion Doctors . Accessed 16 March 2003. By 1791 , Alessandro Volta realized that the frog could be replaced by cardboard soaked in salt water, employing another form of detection. Having already studied the electrostatic phenomenon of Capacitance , Volta was able to quantitatively measure the Electromotive Force (emf) associated with each electrode-electrolyte interface ( Voltage ) in Volt s, which were named after him. Such a device is called a Voltaic Cell , or cell for short. In 1799 , Volta invented the modern battery by placing many galvanic cells in Series , literally piling them one above the other. This Voltaic Pile gave a greatly enhanced net emf for the combination,Willie Weinberg. Volta - The Italian American Website of New York . Accessed 19 March 2007. with a voltage of about 50 volts for a 32-cell pile.Saslow, Ch. 8, p. 338. In many parts of Europe batteries continue to be called piles. Unfortunately, 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, as Michael Faraday showed around 1830, an unavoidable by-product of their operation. Later, researchers placed galvanic cells in Series . Such banks of cells are called batteries, presumably after the earlier use by Benjamin Franklin to describe Leyden Jar s ( Capacitor s) in series and in parallel.Mary Bellis. History of the Electric Battery - About . Accessed 19 March 2007. Although early batteries were of great value for experimental purposes, their limitations made them impractical for large current drain. Later, batteries, starting with the Daniell Cell in 1836 , 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 then. Battery History, Technology, Applications and Development . Accessed 19 March 2007. These wet cells used liquid electrolytes, which were prone to leaks 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 19th century, the invention of dry cell batteries, which replaced liquid electrolyte with a paste made portable electrical devices practical. HOW BATTERIES WORK See Also: Electrochemical cell A battery is a device that converts chemical energy directly to electrical energy.Marshall Brain. "How Batteries Work" - Howstuffworks . Accessed 28 March 2007. It consists of one or more voltaic cells. Each voltaic cell consists of two Half Cell s connected in series by a conductive electrolyte. Each cell has a positive electrode (cathode), and a negative electrode (anode). These do not touch each other but are immersed in a solid or liquid electrolyte. BBC- Rough Science Library . Accessed 28 March 2007. In a practical cell the materials are enclosed in a container, and a separator between the electrodes prevents the electrodes from coming into contact. Each half cell has a net Electromotive Force (or emf), with the net emf of the battery being the difference between the emfs of the half-cells, a fact first recognized by Volta. Thus, if the electrodes have emfs , then the net emf is . (Hence, two identical electrodes and a common electrolyte give zero net emf.) Each half cell emf is due to a charge-transferring (or faradaic) chemical reaction at the electrode-electrolyte interface, which transfers charge across the interface. The reaction stops when the charge transfer is enough to cancel out the tendency of the reaction to occur. Non-charge-transferring, or nonfaradaic, reactions can also occur at the interface. These are undesirable, using up the chemicals without producing current (which is the rate of charge transfer). Additional, but relatively ineffective, faradaic reactions (also called parasitic or "side-reactions") can also occur. The electrical potential difference across the terminals of a battery is known as its ''terminal voltage'', measured in Volt s. The terminal voltage of a battery that is neither charging nor discharging is called the Open-circuit Voltage , and gives the emf of the battery. The terminal voltage of a battery that is discharging is smaller in magnitude than the open-circuit voltage, and the terminal voltage of a battery being charged is greater than the open-circuit voltage. Terminal Voltage - Tiscali Reference . Originally from ''Hutchinson Encyclopaedia''. Accessed 7 April 2007. The voltage developed across a cell's terminals depends on the chemicals used in it and their concentrations. For example, alkaline and carbon-zinc cells both measure about 1.5 volts, due to the energy release of the associated chemical reactions. Because of the high electrochemical potential changes in the reactions of Lithium compounds, lithium cells can provide as much as 3 volts or more. CLASSIFICATION OF BATTERIES Batteries are usually divided into two broad classes:
Historically, some types of primary batteries used, for example, for Telegraph circuits, were restored to operation by replacing the components of the battery consumed by the chemical reaction. Secondary batteries are not indefinitely rechargeable due to dissipation of the active materials, loss of electrolyte, and internal corrosion. TYPES OF BATTERIES s, a 9 volt '' PP3 Battery , a '' AAA Battery '', a '' AA Battery '', a '' C Battery '', a '' D Battery '', a large ''3R12'']] From a user's viewpoint, at least, batteries can be generally divided into two main types: ''non-rechargeable ( Disposable )'' and '' Rechargeable ''. Each is in wide usage. Disposable batteries, also called ''primary cells'', are intended to be used once and discarded. These are most commonly used in portable devices with either low current drain, only used intermittently, or used well away from an alternative power source. Primary cells were also commonly used for alarm and communication circuits where other electric power was only intermittently available. Primary cells cannot be reliably recharged, since the chemical reactions are not easily reversible and active materials may not return to their original forms. Battery manufacturers recommend against attempting to recharge primary cells, although some electronics enthusiasts claim it is possible to do so using a special type of charger. Battery Xtender . Retrieved 7 March 2007. By contrast, rechargeable batteries or ''secondary cells'' can be re-charged by applying electrical current, which reverses the Chemical Reactions that occur in use. Devices to supply the appropriate current are called chargers or rechargers. The oldest form of rechargeable battery still in modern usage is the " gas produced by these batteries during overcharging. The lead-acid battery is also very heavy for the amount of electrical energy it can supply. Despite this, its low manufacturing cost and its high surge current levels make its use common where a large capacity (over approximately 10Ah) is required or where the weight and ease of handling are not concerns. A common form of lead-acid battery is the modern wet-cell Car Battery . This can deliver about 10,000 Watt s of power for a short period, and has a peak current output that varies from 450 to 1100 Ampere s. An improved type of lead-acid battery called a '' Gel Battery '' (or "gel cell") has become popular in automotive industry as a replacement for the lead-acid wet cell. The gel battery contains a semi-solid electrolyte to prevent spillage, electrolyte evaporation, and out-gassing, as well as greatly improving its resistance to damage from vibration and heat. Another type of battery, the '' Absorbed Glass Mat '' (AGM) suspends the electrolyte in a special fiberglass matting to achieve similar results. More portable rechargeable batteries include several "dry cell" types, which are sealed units and are therefore useful in appliances like Mobile Phone s and Laptop s. Cells of this type (in order of increasing Power Density and cost) include Nickel-cadmium (NiCd), Nickel Metal Hydride (NiMH), and Lithium-ion (Li-Ion) cells. Disposable Not designed to be rechargeable - sometimes called "primary cells". "Disposable" may also imply that special disposal procedures must take place for proper disposal according to regulation, depending on battery type.
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