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A primary battery or primary cell is a
battery Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Automotive battery, a device to provide power t ...
(a
galvanic cell A galvanic cell or voltaic cell, named after the scientists Luigi Galvani and Alessandro Volta, respectively, is an electrochemical cell in which an electric current is generated from spontaneous Oxidation-Reduction reactions. A common apparatus ...
) that is designed to be used once and discarded, and not recharged with electricity and reused like a secondary cell (
rechargeable battery A rechargeable battery, storage battery, or secondary cell (formally a type of energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or prima ...
). In general, the
electrochemical Electrochemistry is the branch of physical chemistry concerned with the relationship between electrical potential difference, as a measurable and quantitative phenomenon, and identifiable chemical change, with the potential difference as an outc ...
reaction Reaction may refer to a process or to a response to an action, event, or exposure: Physics and chemistry *Chemical reaction *Nuclear reaction * Reaction (physics), as defined by Newton's third law *Chain reaction (disambiguation). Biology and m ...
occurring in the cell is not reversible, rendering the cell unrechargeable. As a primary cell is used,
chemical reaction A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...
s in the battery use up the chemicals that generate the power; when they are gone, the battery stops producing electricity. In contrast, in a secondary cell, the reaction can be reversed by running a current into the cell with a
battery charger A battery charger, recharger, or simply charger is a device that stores energy in a battery by running an electric current through it. The charging protocol (how much voltage or current for how long, and what to do when charging is complete) depe ...
to recharge it, regenerating the chemical reactants. Primary cells are made in a range of standard sizes to power small household appliances such as
flashlight A flashlight (American English, US, Canadian English, Canada) or torch (British English, UK, Australian English, Australia) is a portable hand-held electric lamp. Formerly, the light source typically was a miniature incandescent light bulb, b ...
s and portable radios. Primary batteries make up about 90% of the $50 billion battery market, but secondary batteries have been gaining market share. About 15 billion primary batteries are thrown away worldwide every year, virtually all ending up in landfills. Due to the toxic heavy metals and strong acids and alkalis they contain, batteries are
hazardous waste Hazardous waste is waste that has substantial or potential threats to public health or the environment. Hazardous waste is a type of dangerous goods. They usually have one or more of the following hazardous traits: ignitability, reactivity, cor ...
. Most municipalities classify them as such and require separate disposal. The energy needed to manufacture a battery is about 50 times greater than the energy it contains. Due to their high pollutant content compared to their small energy content, the primary battery is considered a wasteful, environmentally unfriendly technology. Due mainly to increasing sales of
wireless device Wireless communication (or just wireless, when the context allows) is the transfer of information between two or more points without the use of an electrical conductor, optical fiber or other continuous guided medium for the transfer. The most ...
s and cordless tools which cannot be economically powered by primary batteries and come with integral rechargeable batteries, the secondary battery industry has high growth and has slowly been replacing the primary battery in high end products.


Usage trend

In the early twenty-first century, primary cells began losing market share to secondary cells, as relative costs declined for the latter. Flashlight power demands were reduced by the switch from
incandescent bulb An incandescent light bulb, incandescent lamp or incandescent light globe is an electric light with a wire filament heated until it glows. The filament is enclosed in a glass bulb with a vacuum or inert gas to protect the filament from oxid ...
s to
light-emitting diode A light-emitting diode (LED) is a semiconductor Electronics, device that Light#Light sources, emits light when Electric current, current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy i ...
s. The remaining market experienced increased competition from private- or no-label versions. The market share of the two leading US manufacturers, Energizer and Duracell, declined to 37% in 2012. Along with Rayovac, these three are trying to move consumers from zinc–carbon to more expensive, longer-lasting alkaline batteries. Western battery manufacturers shifted production offshore and no longer make zinc-carbon batteries in the United States. China became the largest battery market, with demand projected to climb faster than anywhere else, and has also shifted to alkaline cells. In other developing countries disposable batteries must compete with cheap wind-up, wind-powered and rechargeable devices that have proliferated.


Comparison between primary and secondary cells

Secondary cells (
rechargeable batteries A rechargeable battery, storage battery, or secondary cell (formally a type of energy accumulator), is a type of electrical battery which can be charged, discharged into a load, and recharged many times, as opposed to a disposable or prima ...
) are in general more economical to use than primary cells. Their initially higher cost and the purchase cost of a charging system can be spread out over many use cycles (between 100 and 1000 cycles); for example, in hand-held power tools, it would be very costly to replace a high-capacity primary battery pack every few hours of use. Primary cells are not designed for recharging between manufacturing and use, thus have battery chemistry that has to have a much lower self-discharge rate than older types of secondary cells; but they have lost that advantage with the development of rechargeable secondary cells with very low
self-discharge Self-discharge is a phenomenon in batteries Battery most often refers to: * Electric battery, a device that provides electrical power * Battery (crime), a crime involving unlawful physical contact Battery may also refer to: Energy source *Au ...
rates like low self-discharge NiMH cells that hold enough charge for long enough to be sold as pre-charged. Common types of secondary cells (namely NiMH and Li-ion) due to their much lower
internal resistance A practical electrical power source which is a linear electric circuit may, according to Thévenin's theorem, be represented as an ideal voltage source in series with an impedance. This impedance is termed the internal resistance of the source. ...
do not suffer the large loss of capacity that alkaline, zinc–carbon and zinc chloride ("heavy duty" or "super heavy duty") do with high current draw. Reserve batteries achieve very long storage time (on the order of 10 years or more) without loss of capacity, by physically separating the components of the battery and only assembling them at the time of use. Such constructions are expensive but are found in applications like
munitions Ammunition (informally ammo) is the material fired, scattered, dropped, or detonated from any weapon or weapon system. Ammunition is both expendable weapons (e.g., bombs, missiles, grenades, land mines) and the component parts of other weap ...
, which may be stored for years before use.


Polarization

A major factor reducing the lifetime of primary cells is that they become ''polarized'' during use. This means that
hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-to ...
accumulates at the cathode and reduces the effectiveness of the cell. To reduce the effects of polarization in commercial cells and to extend their lives, chemical depolarization is used; that is, an
oxidizing agent An oxidizing agent (also known as an oxidant, oxidizer, electron recipient, or electron acceptor) is a substance in a redox chemical reaction that gains or " accepts"/"receives" an electron from a (called the , , or ). In other words, an oxi ...
is added to the cell, to oxidize the hydrogen to water.
Manganese dioxide Manganese dioxide is the inorganic compound with the formula . This blackish or brown solid occurs naturally as the mineral pyrolusite, which is the main ore of manganese and a component of manganese nodules. The principal use for is for dry-ce ...
is used in the Leclanché cell and zinc–carbon cell, and
nitric acid Nitric acid is the inorganic compound with the formula . It is a highly corrosive mineral acid. The compound is colorless, but older samples tend to be yellow cast due to decomposition into oxides of nitrogen. Most commercially available ni ...
is used in the
Bunsen cell The Bunsen cell is a zinc-carbon primary cell (colloquially called a "battery") composed of a zinc anode in dilute sulfuric acid separated by a porous pot from a carbon cathode in nitric or chromic acid. Cell details The Bunsen cell is abou ...
and
Grove cell The Grove cell was an early electric primary cell named after its inventor, Welsh physical scientist William Robert Grove, and consisted of a zinc anode in dilute sulfuric acid and a platinum cathode in concentrated nitric acid, the two separated ...
. Attempts have been made to make simple cells self-depolarizing by roughening the surface of the copper plate to facilitate the detachment of hydrogen bubbles with little success. Electrochemical depolarization exchanges the hydrogen for a metal, such as
copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
(e.g.
Daniell cell The Daniell cell is a type of electrochemical cell invented in 1836 by John Frederic Daniell, a British chemist and meteorologist, and consists of a copper pot filled with a copper (II) sulfate solution, in which is immersed an unglazed earthenw ...
), or
silver Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
(e.g.
silver-oxide cell A silver-oxide battery (IEC code: S) is a primary cell using silver oxide as the cathode material and zinc for the anode. These cells maintain a nearly constant nominal voltage during discharge until fully depleted. They are available in small ...
), so called.


Terminology


Anode and cathode

The battery terminal (
electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials ...
) that develops a positive voltage polarity (the
carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon ma ...
electrode in a dry cell) is called the
cathode A cathode is the electrode from which a conventional current leaves a polarized electrical device. This definition can be recalled by using the mnemonic ''CCD'' for ''Cathode Current Departs''. A conventional current describes the direction in whi ...
and the electrode with a negative polarity (
zinc Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodi ...
in a dry cell) is called the
anode An anode is an electrode of a polarized electrical device through which conventional current enters the device. This contrasts with a cathode, an electrode of the device through which conventional current leaves the device. A common mnemonic is ...
. This is the ''reverse'' of the terminology used in an
electrolytic cell An electrolytic cell is an electrochemical cell that utilizes an external source of electrical energy to force a chemical reaction that would not otherwise occur. The external energy source is a voltage applied between the cell′s two electrod ...
or thermionic
vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied. The type known as ...
. The reason is that the terms anode and cathode are defined by the direction of electric current, not by their voltage. The anode is the terminal through which
conventional current An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving ...
(positive charge) enters the cell from the external circuit, while the cathode is the terminal through which conventional current leaves the cell and flows into the external circuit. Since a battery is a power source which provides the voltage which forces the current through the external circuit, the voltage on the cathode must be higher than the voltage on the anode, creating an electric field directed from cathode to anode, to force the positive charge out of the cathode through the resistance of the external circuit. Inside the cell the anode is the electrode where chemical
oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or ...
occurs, as it donates electrons which flow out of it into the external circuit. The cathode is the electrode where chemical reduction occurs, as it accepts electrons from the circuit. Outside the cell, different terminology is used. As the anode donates positive charge to the electrolyte (thus remaining with an excess of electrons that it will donate to the circuit), it becomes negatively charged and is therefore connected to the terminal marked "−" on the outside of the cell. The cathode, meanwhile, donates negative charge to the electrolyte, so it becomes positively charged (which allows it to accept electrons from the circuit) and is therefore connected to the terminal marked "+" on the outside of the cell. Old textbooks sometimes contain different terminology that can cause confusion to modern readers. For example, a 1911 textbook by Ayrton and MatherW. E. Ayrton and T. Mather, ''Practical Electricity'', Cassell and Company, London, 1911, page 170 describes the electrodes as the "positive plate" and "negative plate" .


See also

*
History of the battery Batteries provided the primary source of electricity before the development of electric generators and electrical grids around the end of the 19th century. Successive improvements in battery technology facilitated major electrical advances, f ...
*
Fuel cell A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen fuel, hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most bat ...
*
Battery recycling Battery recycling is a recycling activity that aims to reduce the number of batteries being disposed as municipal solid waste. Batteries contain a number of heavy metals and toxic chemicals and disposing of them by the same process as regular ...
*
List of battery sizes This is a list of the sizes, shapes, and general characteristics of some common primary and secondary battery types in household, automotive and light industrial use. The complete nomenclature for a battery specifies size, chemistry, termina ...
*
List of battery types This list is a summary of notable electric battery types composed of one or more electrochemical cells. Three lists are provided in the table. The primary (non-rechargeable) and secondary (rechargeable) cell lists are lists of battery chemistry. ...
* Comparison of battery types *
Battery nomenclature Standard battery nomenclature describes portable dry cell batteries that have physical dimensions and electrical characteristics interchangeable between manufacturers. The long history of disposable dry cells means that many manufacturer-specifi ...


References


External links


Nonrechargeable batteries
{{Galvanic cells Battery types Battery (electricity) it:Pila (chimica)