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Benjamin Franklin's famous experiment to attract electricity by flying a kite in a lightning storm was only one of many late eighteenth- and early nineteenth-century experiments conducted to learn about electricity. The first battery was constructed in 1800 by Italian Alessandro Volta. The so-called voltaic pile consisted of alternating discs of silver and zinc separated by leather or pasteboard that had been soaked in salt water, lye, or some alkaline solution. Strips of metal at each end of the pile were connected to small cups filled with mercury. When Volta touched both cups of mercury with his fingers, he received an electric shock; the more discs he assembled, the greater the jolt he received.

Volta's discovery led to further experimentation. In 1813, Sir Humphrey Davy constructed a pile with 2,000 pairs of discs in the basement of the Royal Institution of London. Among other applications, Davy used the electricity he produced for electrolysiscatalyzing chemical reactions by passing a current through substances (Davy separated sodium and potassium from compounds). Only a few years later, Michael Faraday discovered the principle of electromagnetic induction, using a magnet to induce electricity in a coiled wire. This technique is at the heart of the dynamos used to produce electricity in power plants today. (While a dynamo produces alternating current (AC) in which the flow of electricity shifts direction regularly, batteries produce direct current (DC) that flows in one direction only.) A lead-acid cell capable of producing a very large amount of current, the forerunner of today's automobile battery, was devised in 1859 by Frenchman Gaston Planté.

In the United States, Thomas Edison was experimenting with electricity from both batteries and dynamos to power the light bulb, which began to spread in the United States in the early 1880s. During the 1860s, Georges Leclanché invented the wet cell, which, though heavy because of its liquid components, could be sold and used commercially. By the 1870s and 1880s, the Leclanché cell was being produced using dry materials and was used for a number of tasks, including providing power for Alexander Graham Bell's telephone and for the newly-invented flashlight. Batteries were subsequently called upon to provide power for many other inventions, such as the radio, which became hugely popular in the years following World War I. Today, more than twenty billion power cells are sold throughout the world each year, and each American uses approximately 27 batteries annually.


All batteries utilize similar procedures to create electricity; however, variations in materials and construction have produced different types of batteries. Strictly speaking, what is commonly termed a battery is actually a group of linked cells. The following is a simplified description of how a battery works.

Two important parts of any cell are the anode and the cathode. The cathode is a metal that is combined, naturally or in the laboratory, with oxygenthe combination is called an oxide. Iron oxide (rust), although too fragile to use in a battery, is perhaps the most familiar oxide. Some other oxides are actually strong enough to be worked (cut, bent, shaped, molded, and so on) and used in a cell. The anode is a metal that would oxidize if it were allowed to and, other things being equal, is more likely to oxidize than the metal that forms part of the cathode.

A cell produces electricity when one end of a cathode and one end of an anode are placed into a third substance that can conduct electricity, while their other ends are connected. The anode draws oxygen atoms toward it, thereby creating an electric flow. If there is a switch in the circuit (similar to any wall or lamp switch), the circuit is not complete and electricity cannot flow unless the switch is in the closed position. If, in addition to the switch, there is something else in the circuit, such as a light bulb, the bulb will light from the friction of the electrons moving through it.

The third substance into which the anode and the cathode are placed is called an electrolyte. In many cases this material is a chemical combination that has the property of being alkaline. Thus, an alkaline battery is one that makes use of an alkaline electrolyte. A cell will not produce electricity by itself unless it is placed in a circuit that has been rendered complete by a simple switch, or by some other switching connection in the appliance using the battery.

Designing a cell can lead to many variations in type and structure. Not all electrolytes, for example, are alkaline. Additionally, the container for the electrolyte can act as both a container and either the cathode or the anode. Some cells draw their oxygen not from a cathode but right out of the air. Changes in the compositions of the anode and the cathode will provide more or less electricity. Precise adjustment of all of the materials used in a cell can affect the amount of electricity that can be produced, the rate of production, the voltage at which electricity is delivered through the lifetime of the cell, and the cell's ability to function at different temperatures.

All of these possibilities do, in fact, exist, and their various applications have produced the many different types of batteries available today (lithium, mercury, and so on). For years, however, the most common cell has been the 1.5 volt alkaline battery.

Different batteries function better in different circumstances. The alkaline 1.5 volt cell is ideal for photographic equipment, handheld computers and calculators, toys, tape recorders, and other "high drain" uses; it is also good in low temperatures. This cell has a sloping discharge characteristicit loses power gradually, rather than ceasing to produce electricity suddenlyand will lose perhaps four percent of its power per year if left unused on a shelf.

Other types of batteries include a lithium/manganese dioxide battery, which has a flat discharge characteristicit provides approximately the same amount of power at the beginning of its life as at the endand can be used where there is a need for small, high-power batteries (smoke alarms, cameras, memory backups on computers, and so on). Hearing aids, pagers, and some other types of medical equipment frequently use zinc air button type batteries, which provide a high energy density on continuous discharge. A mercury battery is frequently used in many of the same applications as the zinc air battery, because it, too, provides a steady output voltage.

Raw Materials

This section, as well as the following section, will focus on alkaline batteries. In an alkaline battery, the cylinder that contains the cells is made of nickel-plated steel. It is lined with a separator that divides the cathode from the anode and is made of either layered paper or a porous synthetic material. The canister is sealed at one end with an asphalt or epoxy sealant that underlies a steel plate, and at the other with a brass nail driven through the cylinder. This nail is welded to a metal end cap and passed through an exterior plastic seal. Inside the cylinder, the cathode consists of a mixture of manganese dioxide, graphite, and a potassium hydroxide solution; the anode comprises zinc powder and a potassium hydroxide electrolyte.

The Manufacturing

The cathode

  • 1 In an alkaline battery, the cathode actually doubles as part of the container. Huge loads of the constituent ingredientsmanganese dioxide, carbon black (graphite), and an electrolyte (potassium hydroxide in solution)are delivered by train and mixed in very large batches at the production site. The mixture is then granulated and pressed or compacted into hollow cylinders called preforms. Depending on the size of the battery being made, several preforms may be stacked one on top of another in a battery. Alternatively, the series of preforms can be replaced by an extruded ring of the same material.
  • 2 The preforms are next inserted into a nickel-plated steel can; the combination of the preforms and the steel can make up the cathode of the battery. In a large operation, the cans are made at the battery factory using standard cutting and forming techniques. An indentation is made near the top of the can, and an asphalt or epoxy sealant is placed above the indentation to protect against leakage.

The separator

  • 3 A paper separator soaked in the electrolyte solution is then inserted inside the can against the preforms; the separator is made from several pieces of paper laid at crossgrains to each other (like plywood). Looking down at an open can, one would see what looks like a paper cup inserted into the can. The separator keeps the cathode material from coming into contact with the anode material. As an alternative, a manufacturer might use a porous synthetic fiber for the same purpose.

The anode

  • 4 The anode goes into the battery can next. It is a gel composed primarily of zinc powder, along with other materials including a potassium hydroxide electrolyte. This gel has the consistency of a very thick paste. Rather than a solution, it is chemically a suspension, in which particles do not settle (though an appropriate filter could separate them). The gel does not fill the can to the top so as to allow space for the chemical reactions that will occur once the battery is put into use.

The seals

  • 5 Though the battery is able to produce electricity at this point, an open cell is not practical and would exhaust its potential rapidly. The battery needs to be sealed with three connected components. The first, a brass "nail" or long spike, is inserted into the middle of the can, through the gel material and serves as a "current collector." The second is a plastic seal and the third a metal end cap. The nail, which extends about two-thirds of the way into the can, is welded to the metal end cap and then passed through the plastic seal.
  • 6 This seal is significantly thinner in some places than in others, so that if too much gas builds up in the can, the seal will rupture rather than the entire battery. Some battery designs make use of a wax-filled hole in the plastic; excess gas pushes through the wax rather than rupturing the battery. The seal assembly meets the indentation made in the can at the beginning of the process and is crimped in place.
  • 7 The opposite end of the can (the positive end of the battery) is then closed with a steel plate that is either welded in place or glued with an epoxy-type cement.

The label

  • 8 Before the battery leaves the factory, a label is added identifying the type of battery, its size, and other information. The label is often paper that is simply glued to the battery. One large manufacturer has its label design printed on plastic shrink wrap: a loose fitting piece of heat-sensitive plastic is wrapped around the battery can and then exposed to a blast of heat that makes the plastic shrink down to fit tightly around the can.

Quality Control

Because battery technology is not especially new or exotic, quality control and its results are especially important as the basis for brand competition. The ability of a battery to resist corrosion, to operate well under a variety of conditions, to maintain a good shelf and usage life, and other factors, are the direct results of quality control. Batteries and ingredients are inspected and tested at almost all stages of the production process, and the completed batches are subjected to stringent tests.

Environmental Issues

Although making batteries does present some environmental obstacles, none are insurmountable. Zinc and manganese, the major chemicals in alkaline batteries, do not pose environmental difficulties, and both are considered safe by the Food and Drug Administration (FDA). The major potential pollutant in batteries is mercury, which commonly accompanies zinc and which was for many years added to alkaline batteries to aid conductivity and to prevent corrosion. In the mid-1980s, alkaline batteries commonly contained between five and seven percent mercury.

When it became apparent several years ago that mercury was an environmental hazard, manufacturers began seeking ways to produce efficient batteries without it. The primary method of doing this focuses on better purity control of ingredients. Today's alkaline batteries may contain approximately .025 percent mercury. Batteries with no added mercury at all (it is a naturally occurring element, so it would be difficult to guarantee a product free of even trace qualities) are available from some manufacturers and will be the industry-wide rule rather than the exception by the end of 1993.

The Future

Batteries are currently the focus of intense investigation by scientists and engineers around the world. The reason is simple: several key innovations depend on the creation of better batteries. Viable electric automobiles and portable electronic devices that can operate for long periods of time without needing to be recharged must wait until more lightweight and more powerful batteries are developed. Typical lead-acid batteries currently used in automobiles, for instance, are too bulky and cannot store enough electricity to be used in electric automobiles. Lithium batteries, while lightweight and powerful, are prone to leaking and catching fire.

In early 1993, scientists at Arizona State University announced that they had designed a new class of electrolytes by dissolving polypropylene oxide and polyethylene oxide into a lithium salt solution. The new electrolytes appear to be highly conductive and more stable than typical lithium electrolytes, and researchers are now trying to build prototype batteries that use the promising substances.

In the meantime, several manufacturers are developing larger, more powerful nickel-metal hydride batteries for use in portable computers. These new batteries are expected to appear in late 1994.

Where To Learn More


Packaged Power. Duracell International Inc., 1981.


"Plastic May Recharge Battery's Future," Design News. November 17, 1986, p. 24.

Greenberg, Jeff. "Packing Power: Subnotebook Batteries, Power Management," PC Magazine. October 27, 1992, p. 113.

Leventon, William. "The Charge Toward a Better Battery: Designing a Long-Life Battery," Design News. November 23, 1992, p. 91.

Methvin, Dave. "Battery Contenders Face-Off in Struggle To Dominate Market," PC Week. November 12, 1990, p. S21.

Schmidt, K. F. "Rubbery Conductors Aim at Better Batteries," Science News. March 13, 1993, p. 166.

Zimmerman, Michael R. "Better Batteries on the Way: Nickel-Metal Hydride Is Short-Term Winner," PC Week. April 26, 1993, p. 25.

Lawrence H. Berlow

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battery, electric

electric battery, device that converts chemical energy into electrical energy, consisting of a group of electric cells that are connected to act as a source of direct current. The term is also now commonly used for a single cell, such as the alkaline dry cell used in flashlights and portable tape players, but strictly speaking batteries are made up of connected cells encased in a container and fitted with terminals to provide a source of direct electric current at a given voltage. A cell consists of two dissimilar substances, a positive electrode and a negative electrode, that conduct electricity, and a third substance, an electrolyte, that acts chemically on the electrodes. The two electrodes are connected by an external circuit (e.g., a piece of copper wire); the electrolyte functions as an ionic conductor for the transfer of the electrons between the electrodes. The voltage, or electromotive force, depends on the chemical properties of the substances used, but is not affected by the size of the electrodes or the amount of electrolyte.

Batteries are classed as either dry cell or wet cell. In a dry cell the electrolyte is absorbed in a porous medium, or is otherwise restrained from flowing. In a wet cell the electrolyte is in liquid form and free to flow and move. Batteries also can be generally divided into two main types—rechargeable and nonrechargeable, or disposable. Disposable batteries, also called primary cells, can be used until the chemical changes that induce the electrical current supply are complete, at which point the battery is discarded. Disposible batteries are most commonly used in smaller, portable devices that are only used intermittently or at a large distance from an alternative power source or have a low current drain. Rechargeable batteries, also called secondary cells, can be reused after being drained. This is done by applying an external electrical current, which causes the chemical changes that occur in use to be reversed. The external devices that supply the appropriate current are called chargers or rechargers.

The storage battery is generally a battery of the wet-cell type; i.e., it uses a liquid electrolyte and can be recharged many times. The storage battery consists of several cells connected in series. Each cell contains a number of alternately positive and negative plates separated by the liquid electrolyte. The positive plates of the cell are connected to form the positive electrode; similarly, the negative plates form the negative electrode. In the process of charging, the cell is made to operate in reverse of its discharging operation; i.e., current is forced through the cell in the opposite direction, causing the reverse of the chemical reaction that ordinarily takes place during discharge, so that electrical energy is converted into stored chemical energy. The storage battery's greatest use has been in the automobile where it was used to start the internal-combustion engine. Improvements in battery technology have resulted in vehicles—some in commercial use—in which the battery system supplies power to electric drive motors instead.

Batteries are made of a wide variety of electrodes and electrolytes to serve a wide variety of uses. Batteries consisting of carbon-zinc dry cells connected in various ways (as well as batteries consisting of other types of dry cells) are used to power such devices as flashlights, lanterns, and pocket-sized radios and CD players. Alkaline dry cells are an efficient battery type that is both economical and reliable. In alkaline batteries, the hydrous alkaline solution is used as an electrolyte; the dry cell lasts much longer as the zinc anode corrodes less rapidly under basic conditions than under acidic conditions. In the United States the lead storage battery is commonly used. A more expensive type of lead-acid battery called a gel battery (or gel cell) contains a semisolid electrolyte to prevent spillage. More portable rechargeable batteries include several dry-cell types, which are sealed units and are therefore useful in appliances like mobile phones and laptops. Cells of this type (in order of increasing power density and cost) include nickel-cadmium (nicad or NiCd), nickel metal hydride (NiMH), and lithium-ion (Li-Ion) cells.

There is evidence that primitive batteries were used in Iraq and Egypt as early as 200 BC for electroplating and precious metal gilding. In 1748, Benjamin Franklin coined the term battery to describe an array of charged glass plates. However, most historians date the invention of batteries to about 1800 when experiments by Alessandro Volta resulted in the generation of electrical current from chemical reactions between dissimilar metals. Experiments with different combinations of metals and electrolytes continued over the next 60 years. In the 1860s, Georges Leclanche of France developed a carbon-zinc wet cell; nonrechargeable, it was rugged, manufactured easily, and had a reasonable shelf life. Also in the 1860s, Raymond Gaston Plant invented the lead-acid battery. It had a short shelf life, and about 1881 Émile Alphonse Faure developed batteries using a mixture of lead oxides for the positive plate electrolyte with faster reactions and higher efficiency. In 1900, Thomas Alva Edison developed the nickel storage battery, and in 1905 the nickel-iron battery. During World War II the mercury cell was produced. The small alkaline battery was introduced in 1949. In the 1950s the improved alkaline-manganese battery was developed. In 1954 the first solar battery or solar cell was introduced, and in 1956 the hydrogen-oxygen fuel cell was introduced. The 1960s saw the invention of the gel-type electrolyte lead-acid battery. Lithium-ion batteries, wafer thin and powering portable computers, cell phones, and space probes were introduced in the 1990s. Computer chips and sensors now help prolong battery life and speed the charging cycle. Sensors monitor the temperature inside a battery as chemical reactions during the recharging cause it to heat up; microchips control the power flow during recharging so that current flows in rapidly when the batteries are drained and then increasingly slowly as the batteries become fully charged. Another source of technical progress is nanotechnology; research indicates that batteries employing carbon nanotubes will have twice the life of traditional batteries.

See also electric circuit; fuel cell; solar cell.

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A battery is a device for converting chemical energy into electrical energy. Batteries can consist of a single voltaic cell or a series of voltaic cells joined to each other. (In a voltaic cell, electrical energy is produced as the result of a chemical reaction between two different metals immersed in a solution, usually a liquid.) Batteries can be found everywhere in the world around us, from the giant batteries that provide electrical energy in spacecraft to the miniature batteries that power radios and penlights.

The correct use of the term battery is reserved for groups of two or more voltaic cells. The lead storage battery found in automobiles, for example, contains six voltaic cells. However, in common usage, a single cell is often referred to as a battery. For example, the common dry cell battery found in flashlights is really a single voltaic cell.

Types of batteries

Batteries can be classified as primary or secondary batteries (or cells). A primary battery is one designed to be used just once. When the battery has run down (produced all the energy it can), it is discarded. Secondary batteries, on the other hand, can be recharged and reused.

Special Kinds of Batteries

Battery Type Uses and Special Properties
Zinc/manganese alkaline Primary High efficiency: radios, shavers, electronic flash, movie cameras, tape recorders, television sets, clocks, calculators, toys, watches
Mercuric oxide/zinc Primary High energy: watches, hearing aids, walkie-talkies, calculators, microphones, cameras
Silver oxide/zinc Primary Constant voltage: watches, hearing aids, cameras, calculators
Lithium/copper monofluoride Primary High voltage, long shelf life, good low temperature performance: cameras and small appliances
Lithium/sulfur Primary Good cold weather performance: emergency power units
Nickel/cadmium Secondary Constant voltage and high current: portable hand tools and appliances, shavers, toothbrushes, photoflash equipment, tape recorders, radios, television sets, cassette players and recorders, calculators, pagers, laptop computers
Silver/zinc Secondary High power with low weight: underwater equipment, atmospheric and space applications
Sodium/sulfur Secondary High temperature performance

The best known example of a primary battery is probably the common dry cell invented by French engineer Georges Leclanché (18391882). The dry cell consists of a zinc container that supplies electrons to the battery; a carbon rod through which the electrons flow; and a moist paste of zinc chloride and ammonium chloride, which accepts the electrons produced from the zinc. Technically, the zinc container is the anode (the electrode at which electrons are given up to a reaction) and the moist paste is the cathode (the electrode at which electrons are taken up from a reaction) in the cell. The Leclanché cell is called a dry cell because no liquid is present in it. However, it is not really dry because of the presence of the moist paste, which is needed if electrons are to flow through the cell.

The dry cell runs down as the zinc can is slowly used up. At some point there is not enough zinc left to produce electrons at a useable rate. At that point, the dry cell is just thrown away.

Secondary cells. The secondary cell with which you are likely to be familiar is the lead storage battery found in automobiles. The lead storage battery usually consists of six voltaic cells connected to each other. The total amount of energy produced by the battery is equal to the sum of the electrical energy from the six cells. Since each cell produces about two volts, the total energy available from the cell is 12 volts.

As the lead storage battery is used, it runs down. That is, the lead plates in the battery are converted to lead sulfate. Unlike the dry cell, however, this process can be reversed. Electrical current can be passed back into the battery, and lead sulfate is changed back into lead. If you could see the lead plates in a battery, you would see them slowly disappearing when the battery is being used and slowly reappearing when the battery is being recharged. Recharging occurs naturally when the automobile is operating and generating its own electricity or when a source of external current is provided in order to recharge the battery.

[See also Cell, electrochemical; Electrical conductivity; Electric current; Electricity ]

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bat·ter·y / ˈbatərē/ • n. (pl. -ter·ies) 1. a container consisting of one or more cells, in which chemical energy is converted into electricity and used as a source of power: [as adj.] battery power. 2. a fortified emplacement for heavy guns. 3. a set of similar units of equipment, typically when connected together: a battery of equipment to monitor blood pressure. ∎  an extensive series, sequence, or range of things: children given a battery of tests. 4. Law the crime or tort of unconsented physical contact with another person, even where the contact is not violent but merely menacing or offensive. See also assault and battery. 5. (the battery) Baseball the pitcher and the catcher in a game, considered as a unit.

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battery Collection of voltaic cells that convert chemical energy into direct current (DC) electricity. The term is also commonly used for a single cell, particularly the dry, electrochemical cell used in electronic equipment. Most primary cell batteries are not rechargeable; some types of primary cell – such as nickel-cadmium (Nicad) batteries – and all accumulators (storage batteries) can be recharged when a current passed through them in the reverse direction restores the original chemical state. A battery's capacity is normally measured in ampere-hours; one ampere-hour is equal to 3600 coulombs.

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Battery, Electric


BATTERY, ELECTRIC. SeeElectricity and Electronics .

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