View source for Electric battery

{{Short description|Power source with electrochemical cells}}
{{pp|small=yes}}
{{Use dmy dates|date=May 2014}}
{{Infobox electronic component
| name              = Battery
| image             = File:Batteries.jpg
| image_size        = 250
| caption           = Various cells and batteries (top left to bottom right): two [[AA battery|AA]], one [[D battery|D]], one handheld [[ham radio]] battery, two [[9-volt battery|9-volt]] (PP3), two [[AAA battery|AAA]], one [[C battery|C]], one [[camcorder]] battery, one [[cordless phone]] battery
| type              = Power source
| working_principle = [[Electrochemical reactions]], [[Electromotive force]]
| invented          =
| first_produced    = 1800s
| symbol            = [[File:IEEE 315 Fundamental Items Symbols (90).svg|150px]]
| symbol_caption    = The [[electronic symbol|symbol]] for a battery in a [[circuit diagram]]. It originated as a schematic drawing of the earliest type of battery, a [[voltaic pile]].
}}

An '''electric battery''' is a source of [[electric power]] consisting of one or more [[electrochemical cell]]s with external connections<ref>{{cite book|title=Battery Reference Book|edition=third|last=Crompton|first=T. R.|date=2000-03-20|publisher=Newnes|page=Glossary 3|isbn=978-0-08-049995-6|url=https://books.google.com/books?id=QmVR7qiB5AUC&q=battery%20one%20or%20more%20cells&pg=PA11|access-date=2016-03-18}}</ref> for powering [[Electricity|electrical]] devices. When a battery is supplying power, its positive terminal is the [[cathode]] and its negative terminal is the [[anode]].<ref name="Pauling1988">{{cite book|last1=Pauling|first1=Linus|title=General Chemistry|url=https://archive.org/details/generalchemistry00paul_0|url-access=registration|date=1988|publisher=Dover Publications, Inc.|location=New York|isbn=978-0-486-65622-9|page=[https://archive.org/details/generalchemistry00paul_0/page/539 539]|chapter=15: Oxidation-Reduction Reactions; Electrolysis}}<!--|access-date=13 May 2016--></ref> The terminal marked negative is the source of electrons that will flow through an external electric circuit to the positive terminal. When a battery is connected to an external electric load, a [[redox]] reaction converts high-energy reactants to lower-energy products, and the [[Gibbs free energy|free-energy]] difference is delivered to the external circuit as electrical energy. Historically the term "battery" specifically referred to a device composed of multiple cells; however, the usage has evolved to include devices composed of a single cell.<ref>{{cite book|title=Batteries for Portable Devices|first=Gianfranco|last=Pistoia|date=2005-01-25|publisher=Elsevier|isbn=978-0-08-045556-3|page=1|url=https://books.google.com/books?id=XMe1EnEMuMEC&q=battery%20two%20or%20more%20cells&pg=PA1|access-date=2016-03-18}}</ref>

[[Primary battery|Primary]] (single-use or "disposable") batteries are used once and [[disposable product|discarded]], as the [[electrode]] materials are irreversibly changed during discharge; a common example is the [[alkaline battery]] used for [[flashlight]]s and a multitude of portable electronic devices. [[Rechargeable battery|Secondary (rechargeable) batteries]] can be discharged and recharged multiple times using an applied electric current; the original composition of the electrodes can be restored by reverse current. Examples include the [[Lead–acid battery|lead–acid batteries]] used in vehicles and [[lithium-ion]] batteries used for portable electronics such as [[laptop]]s and [[mobile phone]]s.

Batteries come in many shapes and sizes, from miniature cells used to power [[hearing aid]]s and wristwatches to, at the largest extreme, huge battery banks the size of rooms that provide standby or emergency power for [[telephone exchange]]s and computer [[data center]]s. Batteries have much lower [[specific energy]] (energy per unit mass) than common [[fuel]]s such as gasoline. In automobiles, this is somewhat offset by the higher efficiency of electric motors in converting electrical energy to mechanical work, compared to combustion engines.<!-- odd to single out cars here when batteries have advantages over fossil fuels in practically all applications -->

== History ==
{{Expand section|date=February 2022}}
{{Main|History of the battery}}

=== Invention ===
{{Multiple image|total_width=400
| image1   = Pila di Volta.jpg
| caption1 = A [[voltaic pile]], the first battery
| image2   = La pile de Volta (Le Petit journal).jpg
| caption2 = Italian physicist [[Alessandro Volta]] demonstrating his pile to French emperor [[Napoleon Bonaparte]]
}}
[[Benjamin Franklin]] first used the term "battery" in 1749 when he was doing experiments with electricity using a set of linked [[Leyden jar]] capacitors. <ref>{{cite web |title=The history and development of batteries |date=30 April 2015 |url= https://phys.org/news/2015-04-history-batteries.html}}</ref> Franklin grouped a number of the jars into what he described as a "battery", using the military term for weapons functioning together. <ref>{{cite web|url=http://www.benfranklin300.org/frankliniana/result.php?id=72&sec=0|title="Electrical battery" of Leyden jars - The Benjamin Franklin Tercentenary|website=www.benfranklin300.org}}</ref> By multiplying the number of holding vessels, a stronger charge could be stored, and more power would be available on discharge.

Italian physicist [[Alessandro Volta]] built and described the first electrochemical battery, the [[voltaic pile]], in 1800.<ref>[https://archive.today/20120712220408/http://inventors.about.com/library/inventors/bl_Alessandro_Volta.htm Bellis, Mary. Biography of Alessandro Volta, Inventor of the Battery. ''About.com''. Retrieved 7 August 2008]</ref> This was a stack of copper and zinc plates, separated by brine-soaked paper disks, that could produce a steady current for a considerable length of time.  Volta did not understand that the voltage was due to chemical reactions. He thought that his cells were an inexhaustible source of energy,<ref>Stinner, Arthur. [http://home.cc.umanitoba.ca/~stinner/stinner/pdfs/2007-alessandro.pdf Alessandro Volta and Luigi Galvani] {{webarchive|url=https://web.archive.org/web/20080910203520/http://home.cc.umanitoba.ca/~stinner/stinner/pdfs/2007-alessandro.pdf |date=10 September 2008 }} (PDF). Retrieved 11 August 2008.</ref> and that the associated corrosion effects at the electrodes were a mere nuisance, rather than an unavoidable consequence of their operation, as [[Michael Faraday]] showed in 1834.<ref>[https://web.archive.org/web/20190222020750/http://www.ideafinder.com/history/inventions/battery.htm Fascinating facts about the invention of the Electric Battery by Alessandro Volta in 1800. ''The Great Idea Finder''. Retrieved 11 August 2008]</ref>

Although early batteries were of great value for experimental purposes,<ref>for instance, in the discovery of [[Hans_Christian_Ørsted#Electromagnetism|electromagnetism]] in 1820</ref> in practice their voltages fluctuated and they could not provide a large current for a sustained period. The [[Daniell cell]], invented in 1836 by British chemist [[John Frederic Daniell]], was the first practical source of [[electricity]], becoming an industry standard and seeing widespread adoption as a power source for [[electrical telegraph]] networks.<ref>[http://www.mpoweruk.com/history.htm#daniell Battery History, Technology, Applications and Development]. ''MPower Solutions Ltd''. Retrieved 19 March 2007.</ref> It consisted of a copper pot filled with a [[copper sulfate]] solution, in which was immersed an unglazed [[earthenware]] container filled with [[sulfuric acid]] and a zinc electrode.<ref>{{cite web |title=History of the electrical units |first=Gérard |last=Borvon |date=10 September 2012 |publisher=Association S-EAU-S |url=http://seaus.free.fr/spip.php?article964}}</ref>

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 and potentially dangerous. These characteristics made wet cells unsuitable for portable appliances. Near the end of the nineteenth century, the invention of [[dry cell|dry cell batteries]], which replaced the liquid electrolyte with a paste, made portable electrical devices practical.<ref>{{cite web |url = http://portal.acs.org/portal/PublicWebSite/education/whatischemistry/landmarks/drycellbattery/index.htm |archive-url = https://archive.today/20130223055026/http://portal.acs.org/portal/PublicWebSite/education/whatischemistry/landmarks/drycellbattery/index.htm |url-status=dead |archive-date = 23 February 2013 |title = Columbia Dry Cell Battery |publisher = American Chemical Society |work = National Historic Chemical Landmarks |access-date = 25 March 2013 }}</ref>

[[Vacuum tube battery|Batteries in vacuum tube devices]] historically used a wet cell for the "A" battery (to provide power to the filament) and a dry cell for the "B" battery (to provide the plate voltage).{{cn|date=February 2022}}

=== Future ===

Between 2010 and 2018, annual battery demand grew by 30%, reaching a total of 180&nbsp;[[GWh]] in 2018. Conservatively, the growth rate is expected to be maintained at an estimated 25%, culminating in demand reaching 2600 GWh in 2030. In addition, cost reductions are expected to further increase the demand to as much as 3562&nbsp;GWh.<ref name="WEFGBA2019">{{cite report |last1= Brudermüller |first1= Martin |last2=Sobotka |first2= Benedikt |last3= Dominic |first3= Waughray | date = September 2019 | title = Insight Report&nbsp;— A Vision for a Sustainable Battery Value Chain in 2030 : Unlocking the Full Potential to Power Sustainable Development and Climate Change Mitigation | url = http://www3.weforum.org/docs/WEF_A_Vision_for_a_Sustainable_Battery_Value_Chain_in_2030_Report.pdf | publisher   = World Economic Forum & Global Battery Alliance | pages = 11, 29 | access-date = 2 June 2021}}</ref>

Important reasons for this high rate of growth of the electric battery industry include the electrification of transport,<ref name="WEFGBA2019"/> and large-scale deployment in electricity grids,<ref name="WEFGBA2019"/> supported by anthropogenic climate change-driven moves away from fossil-fuel combusted energy sources to cleaner, renewable sources, and more stringent emission regimes.

Distributed electric batteries, such as those used in [[battery electric vehicles]] ([[vehicle-to-grid]]), and in [[home energy storage]], with [[smart metering]] and that are connected to [[smart grid]]s for [[demand response]], are active participants in smart power supply grids.<ref name="Pierluigi2014">{{cite journal |last1=Siano |first1=Pierluigi  |year=2014 |title=Demand response and smart grids-A survey |journal=Renewable and Sustainable Energy Reviews |publisher=Elsevier |volume=30 |pages=461–478 |issn=1364-0321 |doi=10.1016/j.rser.2013.10.022 }}</ref>
New methods of reuse, such as echelon use of partly-used batteries, add to the overall utility of electric batteries, reduce energy storage costs, and also reduce pollution/emission impacts due to longer lives. In echelon use of batteries, [[vehicle electric batteries]] that have their battery capacity reduced to less than 80%, usually after service of 5–8 years, are repurposed for use as backup supply or for renewable energy storage systems.<ref name="Echelon">{{cite conference |title=The applications of echelon use batteries from electric vehicles to distributed energy storage systems |first1=AQ |last1=Pan |first2=XZ |last2=Li |first3=J |last3=Shang |first4=JH |last4=Feng |first5=YB |last5=Tao |first6=JL |last6=Ye |first7=X |last7=Yang |first8=C |last8=Li |first9=QQ |last9=Liao |year=2019 |conference=2019 International Conference on New Energy and Future Energy System (IOP Conf. Series: Earth and Environmental Science) |volume=354 |publisher=IOP Publishing Ltd |id=012012 |doi=10.1088/1755-1315/354/1/012012 |doi-access=free }}</ref>

Grid scale energy storage envisages the large-scale use of batteries to [[battery storage power station|collect and store energy]] from the grid or a power plant and then discharge that energy at a later time to provide electricity or other grid services when needed. Grid scale energy storage (either turnkey or distributed) are important components of smart power supply grids.<ref name="NREL2019">{{cite report | last1=Leisch | first1=Jennifer E. | last2=Chernyakhovskiy | first2=Ilya |date=September 2019 |title=Grid-Scale Battery Storage : Frequently Asked Questions |url=https://www.nrel.gov/docs/fy19osti/74426.pdf |publisher=National Renewable Energy Laboratory (NREL) & greeningthegrid.org  |accessdate=21 May 2021 }}</ref>

== Chemistry and principles ==
{{Main|Electrochemical cell|Voltaic cell}}
[[File:ElectrochemCell.png|thumb|A voltaic cell for demonstration purposes. In this example the two half-cells are linked by a [[salt bridge]] that permits the transfer of ions.]]

Batteries convert [[chemical energy]] directly to [[electrical energy]]. In many cases, the electrical energy released is the difference in the cohesive<ref>{{cite book | title = Solid State Physics | last = Ashcroft | first = N.W. | author2 = Mermin | others = N.D. | year = 1976 | publisher = Brooks/Cole|location=Belmont, CA }}</ref> or bond energies of the metals, oxides, or molecules undergoing the electrochemical reaction. For instance, energy can be stored in Zn or Li, which are high-energy metals because they are not stabilized by d-electron bonding, unlike [[transition metals]]. Batteries are designed so that the energetically favorable [[redox]] reaction can occur only when electrons move through the external part of the circuit.

A battery consists of some number of [[voltaic cell]]s. Each cell consists of two [[half-cell]]s connected in series by a conductive [[electrolyte]] containing metal ''cations''. One half-cell includes electrolyte and the negative electrode, the electrode to which [[Ion#Anions and cations|anions]] (negatively charged ions) migrate; the other half-cell includes electrolyte and the positive electrode, to which [[Ion#Anions and cations|cations]] (positively charged [[ion]]s) migrate. Cations are reduced (electrons are added) at the cathode, while metal atoms are oxidized (electrons are removed) at the anode.<ref>Dingrando 665.</ref> Some cells use different electrolytes for each half-cell; then a separator is used to prevent mixing of the electrolytes while allowing ions to flow between half-cells to complete the electrical circuit.

Each half-cell has an [[electromotive force]] (''emf'', measured in volts) relative to a [[Standard hydrogen electrode|standard]]. The net emf of the cell is the difference between the emfs of its half-cells.<ref name="Saslow 338">Saslow 338.</ref> Thus, if the electrodes have emfs <math>\mathcal{E}_1</math> and <math>\mathcal{E}_2</math>, then the net emf is <math>\mathcal{E}_{2}-\mathcal{E}_{1}</math>; in other words, the net emf is the difference between the [[reduction potential]]s of the [[half-reaction]]s.<ref>Dingrando 666.</ref>

The electrical driving force or <math>\displaystyle{\Delta V_{bat}}</math> across the [[battery terminal|terminals]] of a cell is known as the ''terminal voltage (difference)'' and is measured in [[volt]]s.<ref name="pse943">Knight 943.</ref> The terminal voltage of a cell that is neither charging nor discharging is called the [[open-circuit voltage]] and equals the emf of the cell. Because of internal resistance,<ref name="pse976">Knight 976.</ref> the terminal voltage of a cell that is discharging is smaller in magnitude than the open-circuit voltage and the terminal voltage of a cell that is charging exceeds the open-circuit voltage.<ref>[https://web.archive.org/web/20080411120602/http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0030399.html Terminal Voltage. Tiscali Reference. Originally from ''Hutchinson Encyclopaedia''. Retrieved 7 April 2007]</ref> An ideal cell has negligible internal resistance, so it would maintain a constant terminal voltage of <math>\mathcal{E}</math> until exhausted, then dropping to zero. If such a cell maintained 1.5 volts and produce a charge of one [[coulomb]] then on complete discharge it would have performed 1.5 [[joule]]s of work.<ref name="pse943" /> In actual cells, the internal resistance increases under discharge<ref name="pse976" /> and the open-circuit voltage also decreases under discharge. If the voltage and resistance are plotted against time, the resulting graphs typically are a curve; the shape of the curve varies according to the chemistry and internal arrangement employed.

The [[voltage]] developed across a cell's terminals depends on the energy release of the chemical reactions of its electrodes and electrolyte. [[Alkaline battery|Alkaline]] and [[Zinc–carbon battery|zinc–carbon]] cells have different chemistries, but approximately the same emf of 1.5 volts; likewise [[Nickel–cadmium battery|NiCd]] and [[Nickel–metal hydride battery|NiMH]] cells have different chemistries, but approximately the same emf of 1.2 volts.<ref>Dingrando 674.</ref> The high electrochemical potential changes in the reactions of [[lithium]] compounds give lithium cells emfs of 3 volts or more.<ref>Dingrando 677.</ref>

Almost any liquid or moist object that has enough ions to be electrically conductive can serve as the electrolyte for a cell. As a novelty or science demonstration, it is possible to insert two electrodes made of different metals into a [[lemon battery|lemon]],<ref>{{cite web |url=http://ushistory.org/franklin/fun/lemon.htm |work=ushistory.org |title=The Lemon Battery |access-date=10 April 2007 |archive-url=https://web.archive.org/web/20070509183859/http://www.ushistory.org/franklin/fun/lemon.htm |archive-date=2007-05-09}}</ref> potato,<ref>[http://pbskids.org/zoom/activities/phenom/potatobattery.html ZOOM activities: phenom Potato Battery]. Accessed 10 April 2007.</ref> etc. and generate small amounts of electricity.

A voltaic pile can be made from two coins (such as a nickel and a [[penny]]) and a piece of [[paper towel]] dipped in [[saline water|salt water]]. Such a pile generates a very low voltage but, when many are stacked in [[series circuit|series]], they can replace normal batteries for a short time.<ref>[http://electronics.howstuffworks.com/battery1.htm Howstuffworks "Battery Experiments: Voltaic Pile"]. Accessed 10 April 2007.</ref>

== Types ==
{{See also|Battery nomenclature|List of battery types}}

=== Primary and secondary batteries ===
[[File:Batteries comparison 4,5 D C AA AAA AAAA A23 9V CR2032 LR44 matchstick-vertical.jpeg|thumb|upright|From top to bottom: a large 4.5-volt ''[[3R12]]'' battery, a ''[[D battery|D Cell]]'', a ''[[C battery|C cell]]'', an ''[[AA cell]]'', an ''[[AAA cell]]'', an ''[[AAAA battery|AAAA cell]]'', an ''[[A23 battery]]'', a 9-volt ''[[PP3 battery]]'', and a pair of [[button cell]]s (CR2032 and LR44)]]

Batteries are classified into primary and secondary forms:

* ''Primary'' batteries are designed to be used until exhausted of energy then discarded.  Their chemical reactions are generally not reversible, so they cannot be recharged. When the supply of reactants in the battery is exhausted, the battery stops producing current and is useless.<ref>Dingrando 675.</ref>
* ''Secondary'' batteries can be recharged; that is, they can have their chemical reactions reversed by applying [[electric current]] to the cell.  This regenerates the original chemical reactants, so they can be used, recharged, and used again multiple times.<ref>Fink, Ch. 11, Sec. "Batteries and Fuel Cells."</ref>

Some types of primary batteries used, for example, for [[Telegraphy|telegraph]] circuits, were restored to operation by replacing the electrodes.<ref>[[Franklin Leonard Pope]], ''Modern Practice of the Electric Telegraph 15th Edition'', D. Van Nostrand Company, New York, 1899, pp. 7–11. Available on the [[Internet Archive]]</ref> Secondary batteries are not indefinitely rechargeable due to dissipation of the active materials, loss of electrolyte and internal corrosion.

Primary batteries, or [[primary cell]]s, can produce current immediately on assembly. These are most commonly used in portable devices that have low current drain, are used only intermittently, or are used well away from an alternative power source, such as in alarm and communication circuits where other electric power is only intermittently available. Disposable 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.<ref name="durcar">[http://www.duracell.com/care_disposal/care.asp Duracell: Battery Care]. Retrieved 10 August 2008.</ref> In general, these have higher [[energy densities]] than rechargeable batteries,<ref name="enralk">[http://data.energizer.com/PDFs/alkaline_appman.pdf Alkaline Manganese Dioxide Handbook and Application Manual] (PDF). ''Energizer''. Retrieved 25 August 2008.</ref> but disposable batteries do not fare well under high-drain applications with [[electrical load|loads]] under 75 [[ohm]]s (75 Ω). Common types of disposable batteries include [[zinc–carbon batteries]] and [[alkaline batteries]].

Secondary batteries, also known as ''secondary cells'', or ''[[rechargeable batteries]]'', must be charged before first use; they are usually assembled with active materials in the discharged state. Rechargeable batteries are (re)charged by applying electric current, which reverses the chemical reactions that occur during discharge/use. Devices to supply the appropriate current are called chargers. The oldest form of rechargeable battery is the [[lead–acid battery]], which are widely used in [[automotive]] and [[boating]] applications. This technology contains liquid electrolyte in an unsealed container, requiring that the battery be kept upright and the area be well ventilated to ensure safe dispersal of the [[hydrogen]] gas it produces during [[Overcharging (battery)|overcharging]]. The lead–acid battery is relatively heavy for the amount of electrical energy it can supply. Its low manufacturing cost and its high surge current levels make it common where its capacity (over approximately 10 Ah) is more important than weight and handling issues. A common application is the modern [[car battery]], which can, in general, deliver a peak current of 450 [[ampere]]s.

=== Composition ===
[[File:Dry cell (PSF).png|thumb|upright|Line art drawing of a dry cell: 1. brass cap, 2. plastic seal, 3. expansion space, 4. porous cardboard, 5. zinc can, 6. carbon rod, 7. chemical mixture]]

Many types of electrochemical cells have been produced, with varying chemical processes and designs, including [[galvanic cell]]s, [[electrolytic cell]]s, [[fuel cell]]s, [[flow battery|flow cells]] and voltaic piles.<ref>{{cite web |url=http://www.pspb.org/e21/media/Compare_pvfc_v108_TN.pdf |title=Spotlight on Photovoltaics & Fuel Cells: A Web-based Study & Comparison |access-date=14 March 2007 |pages=1–2 }}</ref>

{{anchor|Wet cell}}
A ''wet cell'' battery has a liquid [[electrolyte]]. Other names are ''flooded cell'', since the liquid covers all internal parts or ''vented cell'', since gases produced during operation can escape to the air. Wet cells were a precursor to dry cells and are commonly used as a learning tool for [[electrochemistry]]. They can be built with common laboratory supplies, such as [[beaker (glassware)|beakers]], for demonstrations of how electrochemical cells work. A particular type of wet cell known as a [[concentration cell]] is important in understanding [[corrosion]]. Wet cells may be [[primary cell]]s (non-rechargeable) or [[secondary cell]]s (rechargeable). Originally, all practical primary batteries such as the [[Daniell cell]] were built as open-top glass jar wet cells. Other primary wet cells are the [[Leclanche cell]], [[Grove cell]], [[Bunsen cell]], [[Chromic acid cell]], [[Clark cell]], and [[Weston cell]]. The Leclanche cell chemistry was adapted to the first dry cells. Wet cells are still used in [[car battery|automobile batteries]] and in industry for standby power for [[switchgear]], telecommunication or large [[uninterruptible power supply|uninterruptible power supplies]], but in many places batteries with [[gel cell]]s have been used instead. These applications commonly use lead–acid or [[Nickel–cadmium battery (vented cell type)|nickel–cadmium]] cells. [[Molten salt battery|Molten salt batteries]] are primary or secondary batteries that use a molten salt as electrolyte. They operate at high temperatures and must be well insulated to retain heat.

A ''[[dry cell]]'' uses a paste electrolyte, with only enough moisture to allow current to flow. Unlike a wet cell, a dry cell can operate in any orientation without spilling, as it contains no free liquid, making it suitable for portable equipment. By comparison, the first wet cells were typically fragile glass containers with lead rods hanging from the open top and needed careful handling to avoid spillage. Lead–acid batteries did not achieve the safety and portability of the dry cell until the development of the [[gel battery]]. A common dry cell is the [[zinc–carbon battery]], sometimes called the dry [[Leclanché cell]], with a nominal voltage of 1.5 [[volt]]s, the same as the [[alkaline battery]] (since both use the same [[zinc]]–[[manganese dioxide]] combination). A standard dry cell comprises a [[zinc]] anode, usually in the form of a cylindrical pot, with a [[carbon]] cathode in the form of a central rod. The electrolyte is [[ammonium chloride]] in the form of a paste next to the zinc anode. The remaining space between the electrolyte and carbon cathode is taken up by a second paste consisting of ammonium chloride and manganese dioxide, the latter acting as a [[depolariser]]. In some designs, the ammonium chloride is replaced by [[zinc chloride]].

A [[reserve battery]] can be stored unassembled (unactivated and supplying no power) for a long period (perhaps years).  When the battery is needed, then it is assembled (e.g., by adding electrolyte); once assembled, the battery is charged and ready to work.  For example, a battery for an electronic artillery [[fuze]] might be activated by the impact of firing a gun. The acceleration breaks a capsule of electrolyte that activates the battery and powers the fuze's circuits. Reserve batteries are usually designed for a short service life (seconds or minutes) after long storage (years). A [[water-activated battery]] for oceanographic instruments or military applications becomes activated on immersion in water.

On 28 February 2017, the [[University of Texas]] at Austin issued a press release about a new type of [[solid-state battery]], developed by a team led by lithium-ion battery inventor [[John Goodenough]], "that could lead to safer, faster-charging, longer-lasting rechargeable batteries for handheld mobile devices, electric cars and stationary energy storage".<ref>{{cite web |url=https://news.utexas.edu/2017/02/28/goodenough-introduces-new-battery-technology |title=Lithium-Ion Battery Inventor Introduces New Technology for Fast-Charging, Noncombustible Batteries |author=<!--Not stated--> |date=28 February 2017 |website=University of Texas at Austin  |publisher=University of Texas |access-date=15 March 2017 }}</ref> The solid-state battery is also said to have "three times the energy density", increasing its useful life in electric vehicles, for example. It should also be more ecologically sound since the technology uses less expensive, earth-friendly materials such as sodium extracted from seawater. They also have much longer life.<ref>{{cite web |url=http://theamericanenergynews.com/markham-on-energy/solid-state-battery-advance-goodenough |title=Solid-state EV battery breakthrough from Li-ion battery inventor John Goodenough |last=Hislop |first=Martin |date=1 March 2017 |website=North American Energy News |publisher=The American Energy News. |access-date=15 March 2017 |quote=But even John Goodenough’s work doesn’t change my forecast that EVs will take at least 50 years to reach 70 to 80 percent of the global vehicle market.}}</ref>

[[Sony]] has developed a [[biological battery]] that generates electricity from sugar in a way that is similar to the processes observed in living organisms. The battery generates electricity through the use of enzymes that break down carbohydrates.<ref>[http://informationweek.com/news/showArticle.jhtml?articleID=201802311 Sony Develops A Bio Battery Powered By Sugar] {{webarchive|url=https://web.archive.org/web/20071011085731/http://informationweek.com/news/showArticle.jhtml?articleID=201802311 |date=11 October 2007 }}. Accessed 24 August 2007.</ref>

The sealed [[valve regulated lead–acid battery]] (VRLA battery) is popular in the automotive industry as a replacement for the lead–acid wet cell. The VRLA battery uses an immobilized [[sulfuric acid]] electrolyte, reducing the chance of leakage and extending [[shelf life]].<ref>[http://www.cdtechno.com/custserv/pdf/7327.pdf Dynasty VRLA Batteries and Their Application] {{webarchive|url=https://web.archive.org/web/20090206105937/http://www.cdtechno.com/custserv/pdf/7327.pdf |date=6 February 2009 }}. ''C&D Technologies, Inc.'' Retrieved 26 August 2008.</ref> VRLA batteries immobilize the electrolyte. The two types are:

* ''[[Gel batteries]]'' (or "gel cell") use a semi-solid electrolyte.
* ''[[Absorbed Glass Mat]]'' (AGM) batteries absorb the electrolyte in a special fiberglass matting.

Other portable rechargeable batteries include several sealed "dry cell" types, that are useful in applications such as mobile phones and [[Laptop|laptop computers]]. Cells of this type (in order of increasing [[power density]] and cost) include [[Nickel–cadmium battery|nickel–cadmium]] (NiCd), [[Nickel–zinc battery|nickel–zinc]] (NiZn), [[Nickel metal hydride battery|nickel metal hydride]] (NiMH), and [[Lithium-ion battery|lithium-ion]] (Li-ion) cells. Li-ion has by far the highest share of the dry cell rechargeable market. NiMH has replaced NiCd in most applications due to its higher capacity, but NiCd remains in use in [[power tool]]s, [[two-way radio]]s, and [[medical equipment]].

In the 2000s, developments include batteries with embedded electronics such as [[USBCELL]], which allows charging an AA battery through a [[USB]] connector, [[nanoball batteries]] that allow for a discharge rate about 100x greater than current batteries,  and [[smart battery]] packs with state-of-charge monitors and battery protection circuits that prevent damage on over-discharge. [[Low self-discharge NiMH battery|Low self-discharge]] (LSD) allows secondary cells to be charged prior to shipping.

[[Lithium–sulfur batteries]] were used on the longest and highest solar-powered flight.<ref>Amos, J. (24 August 2008) [http://news.bbc.co.uk/2/hi/science/nature/7577493.stm "Solar plane makes record flight"] ''BBC News''</ref>

===Consumer and industrial grades===
Batteries of all types are manufactured in consumer and industrial grades. Costlier industrial-grade batteries may use chemistries that provide higher power-to-size ratio, have lower self-discharge and hence longer life when not in use, more resistance to leakage and, for example, ability to handle the high temperature and humidity associated with medical autoclave sterilization.<ref>{{cite magazine |title=Powering Tomorrow's Medicine: Critical Decisions for Batteries in Medical Applications |last=Adams |first=Louis |magazine=Medical Design Briefs |date=November 2015 |url= https://www.medicaldesignbriefs.com/component/content/article/mdb/features/applications/23308}}</ref>

=== Combination and management ===
{{Expand section|date=February 2022}}

Standard-format batteries are inserted into [[battery holder]] in the device that uses them. When a device does not uses standard-format batteries, they are typically combined into a custom [[battery pack]] which holds multiple batteries in addition to features such as a [[battery management system]] and [[battery isolator]] which ensure that the batteries within are charged and discharged evenly.

=== Sizes ===
{{Main|List of battery sizes}}

Primary batteries readily available to consumers range from tiny [[button cell]]s used for electric watches, to the No. 6 cell used for signal circuits or other long duration applications. Secondary cells are made in very large sizes; very large batteries can power a [[submarine]] or stabilize an [[electrical grid]] and help level out peak loads.

{{As of|2017}}, the world's largest battery was built in South Australia by [[Tesla, Inc.|Tesla]]. It can store 129&nbsp;MWh.<ref>{{cite news |title=Elon Musk wins $50m bet with giant battery for South Australia |url=https://news.sky.com/story/elon-musk-wins-50m-bet-with-giant-battery-for-south-australia-11141165 |access-date=20 September 2018 |work=Sky News |date=24 November 2017}}</ref> A battery in [[Hebei Province]], China, which can store 36&nbsp;MWh of electricity was built in 2013 at a cost of $500 million.<ref>{{cite web|last=Dillow |first=Clay |url=http://www.popsci.com/science/article/2012-01/china-builds-worlds-largest-battery-36-megawatt-hour-behemoth |title=China Builds the World's Largest Battery, a Building-Sized, 36-Megawatt-Hour Behemoth &#124; Popular Science |publisher=Popsci.com |date=21 December 2012 |access-date=31 July 2013}}</ref> Another large battery, composed of [[nickel–cadmium battery|Ni–Cd]] cells, was in [[Fairbanks, Alaska]].  It covered {{convert|2000|m2}}—bigger than a football pitch—and weighed 1,300 tonnes. It was manufactured by [[ABB Group|ABB]] to provide backup power in the event of a blackout. The battery can provide 40&nbsp;MW of power for up to seven minutes.<ref>Conway, E. (2 September 2008) [https://archive.today/20121223173018/http://www.telegraph.co.uk/scienceandtechnology/3312118/World%27s-biggest-battery-switched-on-in-Alaska.html "World's biggest battery switched on in Alaska"] ''Telegraph.co.uk''</ref> [[Sodium–sulfur batteries]] have been used to store [[wind power]].<ref>Biello, D. (22 December 2008) [http://www.sciam.com/article.cfm?id=storing-the-breeze-new-battery-might-make-wind-power-reliable "Storing the Breeze: New Battery Might Make Wind Power More Reliable"] ''Scientific American''</ref> A 4.4&nbsp;MWh battery system that can deliver 11&nbsp;MW for 25 minutes stabilizes the output of the Auwahi wind farm in Hawaii.<ref>{{cite web |url=http://www.semprausgp.com/energy-solutions/wind-auwahi-wind.html |title=Auwahi Wind &#124; Energy Solutions &#124; Sempra U.S. Gas & Power, LLC |publisher=Semprausgp.com |access-date=31 July 2013 |archive-url=https://web.archive.org/web/20140502151946/http://www.semprausgp.com/energy-solutions/wind-auwahi-wind.html |archive-date=2 May 2014 |url-status=dead }}</ref>

=== Comparison ===
{{More citations needed|date=June 2021}}
{{Main|Comparison of commercial battery types}}

Many important cell properties, such as voltage, energy density, flammability, available cell constructions, operating temperature range and shelf life, are dictated by battery chemistry.<ref>{{cite web |title=How a battery works |url=https://www.science.org.au/curious/technology-future/batteries |website=Curious |archive-url=https://web.archive.org/web/20220326111716/https://www.science.org.au/curious/technology-future/batteries |archive-date=26 March 2022 |language=en |date=25 February 2016 |url-status=live}}</ref>

{| class="wikitable sortable"
|+ Primary batteries
! Chemistry
! Anode (−)
! Cathode (+)
! Max. voltage, theoretical (V)
! Nominal voltage, practical (V)
! [[Specific energy]] (kJ/kg)
! Elaboration
! Shelf life at 25&nbsp;°C, 80% capacity (months)
|-
| [[Zinc–carbon battery|Zinc–carbon]]
| Zn
| [[Carbon|C]]|| 1.6
| 1.2
| 130
| Inexpensive.
| 18
|-
| [[Zinc–chloride battery|Zinc–chloride]]
| Zn
| C
| 1.5
| 
| 
| Also known as "heavy-duty", inexpensive.
|
|-
| [[Alkaline battery|Alkaline]] (zinc–manganese dioxide)
| Zn
| MnO<sub>2</sub>
| 1.5
| 1.15
| 400-590
| Moderate energy density. Good for high- and low-drain uses.
| 30
|-
| [[Nickel oxyhydroxide battery|Nickel oxyhydroxide]] (zinc–manganese dioxide/nickel oxyhydroxide)
| 
| 
| 1.7
| 
| 
| Moderate energy density. Good for high drain uses. ||
|-
| [[Lithium battery|Lithium]] (lithium–copper oxide) Li–CuO
| Li
| CuO
| 1.7
| 
| 
| No longer manufactured. Replaced by silver oxide ([[International Electrotechnical Commission|IEC]]-type "SR") batteries.
|
|-
| [[Lithium battery|Lithium]] (lithium–iron disulfide) LiFeS<sub>2</sub>
| Li
| FeS<sub>2</sub>
| 1.8
| 1.5
| 1070
| Expensive. Used in 'plus' or 'extra' batteries.
| 337<ref>{{cite web|url=http://data.energizer.com/PDFs/lithiuml91l92_appman.pdf|title=Lithium Iron Disulfide Handbook and Application Manual|website=energizer.com|access-date=20 September 2018|archive-date=17 March 2006|archive-url=https://web.archive.org/web/20060317180835/http://data.energizer.com/PDFs/lithiuml91l92_appman.pdf|url-status=dead}}</ref>
|-
| [[Lithium battery|Lithium]] (lithium–manganese dioxide) LiMnO<sub>2</sub>
| Li
| MnO<sub>2</sub>
| 3.0
| 
| 830–1010
| Expensive. Used only in high-drain devices or for long shelf-life due to very low rate of self-discharge. 'Lithium' alone usually refers to this type of chemistry.
|
|-
| [[Lithium battery|Lithium]] (lithium–carbon fluoride) Li–(CF)<sub>n</sub>
| Li
| (CF)<sub>n</sub>
| 3.6
| 3.0
| 
| 
| 120
|-
| [[Lithium battery|Lithium]] (lithium–chromium oxide) Li–CrO<sub>2</sub>
| Li
| CrO<sub>2</sub>
| 3.8
| 3.0
| 
| 
| 108
|-
| [[Lithium]] ([[Lithium–silicon battery|lithium-silicon]])
| Li<sub>22</sub>Si<sub>5</sub>
|
|
|
|
|
|
|-
| [[Mercury battery|Mercury oxide]]
| Zn
| HgO
| 1.34
| 1.2
| 
| High-drain and constant voltage. Banned in most countries because of health concerns.
| 36
|-
| [[Zinc–air battery|Zinc–air]]
| Zn
| O<sub>2</sub>
| 1.6
| 1.1
| 1590<ref>Excludes the mass of the air oxidizer.</ref>
| Used mostly in hearing aids.
|
|-
| [[Zamboni pile]]
| Zn
| Ag or Au
|  
| 0.8
|  
| Very long life. Very low (nanoamp, nA) current
| >2,000
|-
| [[Silver oxide battery|Silver oxide]] (silver–zinc)
| Zn
| Ag<sub>2</sub>O
| 1.85
| 1.5
| 470
| Very expensive. Used only commercially in 'button' cells.
| 30
|-
| [[Magnesium]]
| Mg
| MnO<sub>2</sub>
| 2.0
| 1.5
| 
| 
| 40
|}

{| class="wikitable sortable"
|+ Secondary batteries
! Chemistry
! Cell voltage
! [[Specific energy]] (kJ/kg)
! [[Energy density]] (kJ/liter)
! Comments
|-
| [[Nickel–cadmium battery|NiCd]]
| 1.2
| 140
| 
| Inexpensive. High-/low-drain, moderate energy density. Can withstand very high discharge rates with virtually no loss of capacity. Moderate rate of self-discharge. Environmental hazard due to Cadmium, use now virtually prohibited in Europe.
|-
| [[Lead–acid battery|Lead–acid]]
| 2.1
| 140
| 
| Moderately expensive. Moderate energy density. Moderate rate of self-discharge. Higher discharge rates result in considerable loss of capacity. Environmental hazard due to Lead. Common use: automobile batteries
|-
| [[Nickel–metal hydride battery|NiMH]]
| 1.2
| 360
| 
| Inexpensive. Performs better than alkaline batteries in higher drain devices. Traditional chemistry has high energy density, but also a high rate of self-discharge. Newer chemistry has [[Low self-discharge NiMH battery|low self-discharge rate]], but also a ~25% lower energy density. <br />Used in some cars.
|-
| [[Nickel–zinc battery|NiZn]]
| 1.6
| 360
| 
| Moderately inexpensive. High drain device suitable. Low self-discharge rate. Voltage closer to alkaline primary cells than other secondary cells. No toxic components. Newly introduced to the market (2009). Has not yet established a track record. Limited size availability.
|-
| [[Silver oxide battery|AgZn]]
| 1.86 1.5
| 460
| 
| Smaller volume than equivalent Li-ion. Extremely expensive due to silver. Very high energy density. Very high drain capable. For many years considered obsolete due to high silver prices. Cell suffers from oxidation if unused. Reactions are not fully understood. Terminal voltage very stable but suddenly drops to 1.5 volts at 70–80% charge (believed to be due to presence of both argentous and argentic oxide in positive plate; one is consumed first). Has been used in lieu of primary battery (moon buggy). Is being developed once again as a replacement for Li-ion.
|-
| [[Lithium iron phosphate battery|LiFePO<sub>4</sub>]]
| 3.3 3.0|| 360
| 790
| Lithium-Iron-Phosphate chemistry.
|-
| [[Lithium-ion battery|Lithium ion]]
| 3.6
| 460
| 
| Very expensive. Very high energy density. Not usually available in "common" battery sizes. [[Lithium polymer battery]] is common in laptop computers, digital cameras, camcorders, and cellphones. Very low rate of self-discharge.  Terminal voltage varies from 4.2 to 3.0 volts during discharge. Volatile: Chance of explosion if short-circuited, allowed to overheat, or not manufactured with rigorous quality standards.
|}

== Performance, capacity and discharge{{anchor|Capacity_and_discharge}} ==
[[File:Battery checker.jpg|thumb|upright|A device to check battery voltage]]
{{See also|State of charge|Depth of discharge|Trickle charging}}

A battery's characteristics may vary over load cycle, over [[charge cycle]], and over lifetime due to many factors including internal chemistry, [[Electric current|current]] drain, and temperature. At low temperatures, a battery cannot deliver as much power. As such, in cold climates, some car owners install battery warmers, which are small electric heating pads that keep the car battery warm.

A battery's ''capacity'' is the amount of [[electric charge]] it can deliver at the rated voltage. The more electrode material contained in the cell the greater its capacity. A small cell has less capacity than a larger cell with the same chemistry, although they develop the same open-circuit voltage.<ref name=aappc /> Capacity is measured in units such as [[amp-hour]] (A·h). The rated capacity of a battery is usually expressed as the product of 20 hours multiplied by the current that a new battery can consistently supply for 20 hours at {{convert|68|F|C}}, while remaining above a specified terminal voltage per cell. For example, a battery rated at 100&nbsp;A·h can deliver 5&nbsp;A over a 20-hour period at [[room temperature]]. The fraction of the stored charge that a battery can deliver depends on multiple factors, including battery chemistry, the rate at which the charge is delivered (current), the required terminal voltage, the storage period, ambient temperature and other factors.<ref name="aappc">[http://www.aaportablepower.com/BatteryKnowledge/BatteryKnowledge.asp Battery Knowledge&nbsp;– AA Portable Power Corp. Retrieved 16 April 2007.] {{webarchive |url=https://web.archive.org/web/20070523105752/http://www.aaportablepower.com/BatteryKnowledge/BatteryKnowledge.asp |date=23 May 2007 }}</ref>

The higher the discharge rate, the lower the capacity.<ref name="techlib">{{cite web|url=http://www.techlib.com/reference/batteries.html|title=Battery Capacity|work=techlib.com}}</ref> The relationship between current, discharge time and capacity for a lead acid battery is approximated (over a typical range of current values) by [[Peukert's law]]:

:<math>t = \frac {Q_P} {I^k}</math>

where

:<math>Q_P</math> is the capacity when discharged at a rate of 1 amp.
:<math>I</math> is the current drawn from battery ([[Amperes|A]]).
:<math>t</math> is the amount of time (in hours) that a battery can sustain.
:<math>k</math> is a constant around 1.3.

Batteries that are stored for a long period or that are discharged at a small fraction of the capacity lose capacity due to the presence of generally irreversible ''side reactions'' that consume charge carriers without producing current. This phenomenon is known as internal self-discharge. Further, when batteries are recharged, additional side reactions can occur, reducing capacity for subsequent discharges. After enough recharges, in essence all capacity is lost and the battery stops producing power. Internal energy losses and limitations on the rate that ions pass through the electrolyte cause battery [[Efficient energy use|efficiency]] to vary. Above a minimum threshold, discharging at a low rate delivers more of the battery's capacity than at a higher rate. Installing batteries with varying A·h ratings does not affect device operation (although it may affect the operation interval) rated for a specific voltage unless load limits are exceeded. High-drain loads such as [[digital camera]]s can reduce total capacity, as happens with alkaline batteries. For example, a battery rated at 2&nbsp;A·h for a 10- or 20-hour discharge would not sustain a current of 1&nbsp;A for a full two hours as its stated capacity implies.

The [[Battery charger#C-rate|C-rate]] is a measure of the rate at which a battery is being charged or discharged. It is defined as the current through the battery divided by the theoretical current draw under which the battery would deliver its nominal rated capacity in one hour.<ref>[http://web.mit.edu/evt/summary_battery_specifications.pdf A Guide to Understanding Battery Specifications], MIT Electric Vehicle Team, December 2008</ref> It has the units [[hour|h]]<sup>−1</sup>. Because of internal resistance loss and the chemical processes inside the cells, a battery rarely delivers nameplate rated capacity in only one hour. Typically, maximum capacity is found at a low C-rate, and charging or discharging at a higher C-rate reduces the usable life and capacity of a battery. Manufacturers often publish datasheets with graphs showing capacity versus C-rate curves. C-rate is also used as a rating on batteries to indicate the maximum current that a battery can safely deliver in a circuit. Standards for rechargeable batteries generally rate the capacity and charge cycles over a 4-hour (0.25C), 8 hour (0.125C) or longer discharge time. Types intended for special purposes, such as in a computer [[uninterruptible power supply]], may be rated by manufacturers for discharge periods much less than one hour (1C) but may suffer from limited cycle life.

{{As of|2012}}, [[lithium iron phosphate battery|lithium iron phosphate ({{chem|LiFePO|4}}) battery technology]] was the fastest-charging/discharging, fully discharging in 10–20 seconds.<ref>{{cite journal | last1 = Kang | first1 = B. | last2 = Ceder | first2 = G. | doi = 10.1038/nature07853 | title = Battery materials for ultrafast charging and discharging | journal = Nature | volume = 458 | issue = 7235 | pages = 190–193 | year = 2009 | pmid =  19279634|bibcode = 2009Natur.458..190K | s2cid = 20592628 }} [http://media.nature.com/download/nature/nature/podcast/v458/n7235/nature-2009-03-12.mp3 1:00–6:50 (audio)] {{webarchive|url=https://web.archive.org/web/20120222092433/http://media.nature.com/download/nature/nature/podcast/v458/n7235/nature-2009-03-12.mp3 |date=22 February 2012 }}</ref>

== Lifespan ==
[[File:2011-04-04 18-35-26 267.jpg|thumb|An analog camcorder [lithium ion] battery ]]
{{See also|State of health}}

Battery life (and its synonym battery lifetime) has two meanings for rechargeable batteries but only one for non-chargeables. For rechargeables, it can mean either the length of time a device can run on a fully charged battery or the number of charge/discharge cycles possible before the cells fail to operate satisfactorily. For a non-rechargeable these two lives are equal since the cells last for only one cycle by definition. The term ''shelf life'' is used to describe how long a battery will retain its performance between manufacture and use. Available capacity of all batteries drops with decreasing temperature. In contrast to most of today's batteries, the [[Zamboni pile]], invented in 1812, offers a very long service life without refurbishment or recharge, although it supplies current only in the nanoamp range. The [[Oxford Electric Bell]] has been ringing almost continuously since 1840 on its original pair of batteries, thought to be Zamboni piles.{{citation needed|date=November 2019}}

Disposable batteries typically lose 8–20% of their original charge per year when stored at room temperature (20–30&nbsp;°C).<ref>[http://www.corrosion-doctors.org/Batteries/self-compare.htm Self discharge of batteries. Corrosion Doctors. Retrieved 9 September 2007]</ref> This is known as the "self-discharge" rate, and is due to non-current-producing "side" chemical reactions that occur within the cell even when no load is applied. The rate of side reactions is reduced for batteries stored at lower temperatures, although some can be damaged by freezing. Old rechargeable batteries self-discharge more rapidly than disposable alkaline batteries, especially nickel-based batteries; a freshly charged nickel cadmium (NiCd) battery loses 10% of its charge in the first 24 hours, and thereafter discharges at a rate of about 10% a month. However, newer [[Low self-discharge NiMH battery|low self-discharge nickel metal hydride (NiMH) batteries]] and modern lithium designs display a lower self-discharge rate (but still higher than for primary batteries).

The active material on the battery plates changes chemical composition on each charge and discharge cycle; active material may be lost due to physical changes of volume, further limiting the number of times the battery can be recharged. Most nickel-based batteries are partially discharged when purchased, and must be charged before first use.<ref>[http://www.energizer.com/products/hightech-batteries/rechargeables/faq/Pages/faq.aspx Energizer Rechargeable Batteries and Chargers: Frequently Asked Questions] {{webarchive|url=https://web.archive.org/web/20090209174717/http://energizer.com/products/hightech-batteries/rechargeables/faq/Pages/faq.aspx |date=9 February 2009 }}. ''Energizer''. Retrieved 3 February 2009.</ref> Newer NiMH batteries are ready to be used when purchased, and have only 15% discharge in a year.<ref>{{cite web|url=https://www.panasonic-eneloop.eu/|archiveurl=https://web.archive.org/web/20100202012558/http://www.eneloop.info/home/performance-details/self-discharge.html|url-status=dead|title=eneloop, environmentally friendly and energy saving batteries &#124; Panasonic eneloop|archivedate=2 February 2010|website=www.panasonic-eneloop.eu}}</ref>

Some deterioration occurs on each charge–discharge cycle. Degradation usually occurs because electrolyte migrates away from the electrodes or because active material detaches from the electrodes. Low-capacity NiMH batteries (1,700–2,000&nbsp;mA·h) can be charged some 1,000 times, whereas high-capacity NiMH batteries (above 2,500&nbsp;mA·h) last about 500 cycles.<ref name="tomdistr">[https://web.archive.org/web/20070808232821/http://nimhbattery.com/batteries-rechargeable-tips-win.htm Rechargeable battery Tips. NIMH Technology Information. Retrieved 10 August 2007]</ref> NiCd batteries tend to be rated for 1,000 cycles before their internal resistance permanently increases beyond usable values. Fast charging increases component changes, shortening battery lifespan.<ref name=tomdistr /> If a charger cannot detect when the battery is fully charged then overcharging is likely, damaging it.<ref>[http://www.greenbatteries.com/batterymyths.html Battery Myths vs Battery Facts. Retrieved 10 August 2007]</ref>

NiCd cells, if used in a particular repetitive manner, may show a decrease in capacity called "[[memory effect]]".<ref>{{cite web|url=http://www.repairfaq.org/ELE/F_Battery_info.html|title=Sci.Electronics FAQ: More Battery Info|author=Filip M. Gieszczykiewicz|work=repairfaq.org}}</ref> The effect can be avoided with simple practices. NiMH cells, although similar in chemistry, suffer less from memory effect.<ref>{{citation |url=http://rechargeablebatteryinfo.com/rechargeable-batteries-memory-effect.php |title=What does 'memory effect' mean? |date=28 October 2005 |editor=RechargheableBatteryInfo.com |access-date=10 August 2007 |archive-url=https://web.archive.org/web/20070715173404/http://rechargeablebatteryinfo.com/rechargeable-batteries-memory-effect.php |archive-date=15 July 2007 <!-- 173404 -->  }}</ref>

[[automotive battery|Automotive]] [[lead–acid]] rechargeable batteries must endure stress due to vibration, shock, and temperature range. Because of these stresses and [[Lead–acid battery#Sulfation|sulfation]] of their lead plates, few automotive batteries last beyond six years of regular use.<ref>Rich, Vincent (1994). ''The International Lead Trade''. Cambridge: Woodhead. 129.</ref> Automotive starting <small>([[automotive battery|SLI]]: ''Starting, Lighting, Ignition'')</small> batteries have many thin plates to maximize current. In general, the thicker the plates the longer the life. They are typically discharged only slightly before recharge. "Deep-cycle" lead–acid batteries such as those used in electric golf carts have much thicker plates to extend longevity.<ref>[http://www.windsun.com/Batteries/Battery_FAQ.htm Deep Cycle Battery FAQ] {{webarchive|url=https://web.archive.org/web/20100722144045/http://www.windsun.com/Batteries/Battery_FAQ.htm |date=22 July 2010 }}. ''Northern Arizona Wind & Sun''. Retrieved 3 February 2009.</ref> The main benefit of the lead–acid battery is its low cost; its main drawbacks are large size and weight for a given capacity and voltage. Lead–acid batteries should never be discharged to below 20% of their capacity,<ref>[http://www.rpc.com.au/products/batteries/car-deepcycle/carfaq14.htm Car and Deep Cycle Battery FAQ] {{Webarchive|url=https://web.archive.org/web/20201106155745/https://www.rpc.com.au/403.shtml |date=6 November 2020 }}. ''Rainbow Power Company''. Retrieved 3 February 2009.</ref> because internal resistance will cause heat and damage when they are recharged. Deep-cycle lead–acid systems often use a low-charge warning light or a low-charge power cut-off switch to prevent the type of damage that will shorten the battery's life.<ref>[http://www.energymatters.com.au/renewable-energy/batteries Deep cycle battery guide] {{webarchive|url=https://web.archive.org/web/20090217030702/http://www.energymatters.com.au/renewable-energy/batteries/ |date=17 February 2009 }}. ''Energy Matters''. Retrieved 3 February 2009.</ref>

Battery life can be extended by storing the batteries at a low temperature, as in a [[refrigerator]] or [[freezer]], which slows the side reactions. Such storage can extend the life of alkaline batteries by about 5%; rechargeable batteries can hold their charge much longer, depending upon type.<ref>[http://ask.yahoo.com/ask/20011219.html Ask Yahoo: Does putting batteries in the freezer make them last longer?] {{webarchive|url=https://web.archive.org/web/20060427025118/http://ask.yahoo.com/ask/20011219.html |date=27 April 2006 }}. Retrieved 7 March 2007.</ref> To reach their maximum voltage, batteries must be returned to room temperature; discharging an alkaline battery at 250&nbsp;mA at 0&nbsp;°C is only half as efficient as at 20&nbsp;°C.<ref name="enralk" /> Alkaline battery manufacturers such as [[Duracell]] do not recommend refrigerating batteries.<ref name="durcar" />

== Hazards ==
{{More citations needed section|date=April 2017}}
{{See also|Lithium-ion battery#Safety|Battery leakage}}
[[File:BATTERY EXPLOSION IN TEST CELL - NARA - 17443202.jpg|thumb|Battery after explosion]]

A battery explosion is generally caused by misuse or malfunction, such as attempting to recharge a primary (non-rechargeable) battery, or a [[short circuit]].

When a battery is recharged at an excessive rate, an explosive gas mixture of [[hydrogen]] and [[oxygen]] may be produced faster than it can escape from within the battery (e.g. through a built-in vent), leading to pressure build-up and eventual bursting of the battery case. In extreme cases, battery chemicals may spray violently from the casing and cause injury. An expert summary of the problem indicates that this type uses "liquid electrolytes to transport lithium ions between the anode and the cathode. If a battery cell is charged too quickly, it can cause a short circuit, leading to explosions and fires".<ref>{{cite web |url=http://theamericanenergynews.com/markham-on-energy/solid-state-battery-advance-goodenough |title=Solid-state EV battery breakthrough from Li-ion battery inventor John Goodenough |last=Hislop |first=Martin |date=1 March 2017 |website=North American Energy News |publisher=The American Energy News. |access-date=15 March 2017}}</ref><ref>{{cite web|url=https://www.youtube.com/playlist?list=PLAAoauVs9gEUQ1QfaueaDCjTMb9LoPEjX|title=battery hazards|website=YouTube|access-date=20 September 2018}}</ref> Car batteries are most likely to explode when a short circuit generates very large currents. Such batteries produce [[hydrogen]], which is very explosive, when they are overcharged (because of [[electrolysis]] of the water in the electrolyte). During normal use, the amount of overcharging is usually very small and generates little hydrogen, which dissipates quickly. However, when "jump starting" a car, the high current can cause the rapid release of large volumes of hydrogen, which can be ignited explosively by a nearby spark, e.g. when disconnecting a [[jumper cable]].

Overcharging (attempting to charge a battery beyond its electrical capacity) can also lead to a battery explosion, in addition to [[Battery leakage|leakage]] or irreversible damage. It may also cause damage to the charger or device in which the overcharged battery is later used.

Disposing of a battery via incineration may cause an explosion as steam builds up within the sealed case.

[[File:LeakedBattery 2701a.jpg|thumb|[[Battery leakage|Leak]]-damaged alkaline battery]]

Many battery chemicals are corrosive, poisonous or both. If [[Battery leakage|leakage]] occurs, either spontaneously or through accident, the chemicals released may be dangerous. For example, disposable batteries often use a zinc "can" both as a reactant and as the container to hold the other reagents. If this kind of battery is over-discharged, the reagents can emerge through the cardboard and plastic that form the remainder of the container. The active chemical leakage can then damage or disable the equipment that the batteries power. For this reason, many electronic device manufacturers recommend removing the batteries from devices that will not be used for extended periods of time.

Many types of batteries employ toxic materials such as lead, [[mercury (element)|mercury]], and [[cadmium]] as an electrode or electrolyte. When each battery reaches end of life it must be disposed of to prevent environmental damage.<ref>[https://web.archive.org/web/20060929214808/http://www.epa.gov/epr/products/batteries.htm Batteries. ''EPA''. Retrieved 11 September 2007]</ref> Batteries are one form of [[electronic waste]] (e-waste). [[E-waste recycling]] services recover toxic substances, which can then be used for new batteries.<ref>[http://earth911.org/recycling/battery-recycling Battery Recycling » Earth 911] {{webarchive|url=https://web.archive.org/web/20081012165626/http://earth911.org/recycling/battery-recycling/ |date=12 October 2008 }}. Retrieved 9 September 2007.</ref> Of the nearly three billion batteries purchased annually in the United States, about 179,000 tons end up in landfills across the country.<ref>"San Francisco Supervisor Takes Aim at Toxic Battery Waste". ''Environmental News Network'' (11 July 2001).</ref>

{{Further|Lithium battery#Health issues on ingestion|Button cell#Accidental ingestion}}

Batteries may be harmful or fatal if [[swallowing|swallowed]].<ref>{{Cite web |url=http://data.energizer.com/PDFs/carbonzinc_psds.pdf |title=Product Safety DataSheet. Energizer (p. 2). Retrieved 9 September 2007 |access-date=9 September 2007 |archive-date=27 September 2007 |archive-url=https://web.archive.org/web/20070927032444/http://data.energizer.com/PDFs/carbonzinc_psds.pdf |url-status=dead }}</ref> Small [[button cell]]s can be swallowed, in particular by young children. While in the digestive tract, the battery's electrical discharge may lead to tissue damage;<ref>{{cite web|url=http://www.poison.org/battery/ |title=Swallowed a Button Battery? &#124; Battery in the Nose or Ear? |publisher=Poison.org |date=3 March 2010 |access-date=26 July 2013 |url-status=dead |archive-url=https://web.archive.org/web/20130816183602/http://www.poison.org/battery/ |archive-date=16 August 2013 }}</ref> such damage is occasionally serious and can lead to death. Ingested disk batteries do not usually cause problems unless they become lodged in the [[gastrointestinal tract]]. The most common place for disk batteries to become lodged is the esophagus, resulting in clinical [[sequelae]]. Batteries that successfully traverse the esophagus are unlikely to lodge elsewhere. The likelihood that a disk battery will lodge in the esophagus is a function of the patient's age and battery size. Older children do not have problems with batteries smaller than 21–23&nbsp;mm. Liquefaction necrosis may occur because sodium hydroxide is generated by the current produced by the battery (usually at the anode). Perforation has occurred as rapidly as 6 hours after ingestion.<ref>{{citation|url=http://emedicine.medscape.com/article/774838-overview|title=Disk Battery Ingestion: Background, Pathophysiology, Epidemiology |last=Dire |first=Daniel J. |editor-last=Vearrier |editor-first=David |work=Medscape |date=2016-06-09 |url-access=registration}}</ref>

== Legislation and regulation ==
{{Expand section|date=February 2022}}
{{See also|Battery regulations in the United Kingdom}}

Legislation around electric batteries includes such topics as safe disposal and recycling.

In the United States, the [[Mercury-Containing and Rechargeable Battery Management Act]] of 1996 banned the sale of mercury-containing batteries, enacted uniform labeling requirements for rechargeable batteries and required that rechargeable batteries be easily removable.<ref>{{cite web |title=Mercury-Containing and Rechargeable Battery Management Act |url=https://www.epa.gov/sites/production/files/2016-03/documents/p1104.pdf |website=EPA |access-date=15 February 2021}}</ref> California and New York City prohibit the disposal of rechargeable batteries in solid waste.<ref name="C2R_NY">{{cite web |url=https://www.call2recycle.org/newyork/ |title=Battery Recycling in New York... it's the law! |date=31 October 2013 |publisher=call2recycle.org |accessdate=2 June 2021}}</ref><ref name="RCBRA2006">{{citation | title = Bill No. 1125 - Rechargeable Battery Recycling Act of 2006, State of California | year = 2006 | url =http://www.leginfo.ca.gov/pub/05-06/bill/asm/ab_1101-1150/ab_1125_bill_20051006_chaptered.pdf | accessdate = 2 June 2021}}</ref> The rechargeable battery industry operates nationwide recycling programs in the United States and Canada, with dropoff points at local retailers.<ref name="rbrc">{{cite web |url=http://www.rbrc.org/consumer/howitallworks_faq.shtml |title=Rechargeable Battery Recycling Corporation |website=www.rbrc.org |access-date=15 January 2022 |archive-url=https://web.archive.org/web/20080812080100/http://www.rbrc.org/consumer/howitallworks_faq.shtml |archive-date=12 August 2008 |url-status=dead}}</ref>

The [[Battery Directive]] of the European Union has similar requirements, in addition to requiring increased recycling of batteries and promoting research on improved [[battery recycling]] methods.<ref>[http://europa.eu/legislation_summaries/environment/waste_management/l21202_en.htm Disposal of spent batteries and accumulators]. ''European Union''. Retrieved 27 July 2009.</ref> In accordance with this directive all batteries to be sold within the EU must be marked with the "collection symbol" (a crossed-out wheeled bin). This must cover at least 3% of the surface of prismatic batteries and 1.5% of the surface of cylindrical batteries. All packaging must be marked likewise.<ref>{{cite web|url=http://www.epbaeurope.net/documents/Newmarkingguidelines_final8March2011.pdf|archiveurl=https://web.archive.org/web/20111007014932/http://www.epbaeurope.net/documents/Newmarkingguidelines_final8March2011.pdf|title=Guidelines on Portable Batteries Marking Requirements in the European Union 2008 | publisher = EPBA-EU|archivedate=7 October 2011}}</ref>

In response to reported accidents and failures, occasionally ignition or explosion, recalls of devices using lithium-ion batteries have become more common in recent years.<ref>{{cite web |url=http://electronics360.globalspec.com/article/5555/lithium-batteries-the-pros-and-cons |title=Lithium Batteries: The Pros and Cons |last=Schweber |first=Bill |date=August 4, 2015 |website=GlobalSpec |publisher=GlobalSpec |access-date=March 15, 2017}}</ref><ref>{{cite news |last=Fowler |first=Suzanne |date=21 September 2016 |title=Samsung's Recall&nbsp;– The Problem with Lithium Ion Batteries  |url=https://www.nytimes.com/2016/09/03/technology/samsungs-recall-the-problem-with-lithium-ion-batteries.html?_r=0 | work=[[The New York Times]] |location=New York |access-date=15 March 2016}}</ref>

On 2022-12-09, the [[EU Parliament]] reached an agreement to force, from 2026, manufacturers to design all electrical appliances sold in the EU (and not used predominantly in wet conditions) so that consumers can easily remove and replace batteries themselves.<ref>{{cite web |title=Batteries: deal on new EU rules for design, production and waste treatment |date=2022-12-09 |work=News European Parliament |publisher=[[European Parliament]] |type=Press release |url=https://www.europarl.europa.eu/news/en/press-room/20221205IPR60614/ |access-date=2022-12-11 |url-status=live |archive-url=https://web.archive.org/web/20221211102055/https://www.europarl.europa.eu/news/en/press-room/20221205IPR60614/batteries-deal-on-new-eu-rules-for-design-production-and-waste-treatment |archive-date=2022-12-11}}</ref><ref>{{cite news |title=Neue EU-Regeln: Jeder soll Handy-Akkus selbst tauschen können |language=de |trans-title=New EU rules: Everyone should be able to replace smartphone batteries themselves |date=2022-12-09 |work=[[Der Spiegel]] |department=Wirtschaft |url=https://www.spiegel.de/wirtschaft/neue-eu-regeln-jeder-soll-handy-akkus-tauschen-koennen-a-06ae1024-8fbf-44c5-a420-70be35c1a401 |access-date=2022-12-11 |url-status=live |archive-url=https://web.archive.org/web/20221211102933/https://www.spiegel.de/wirtschaft/neue-eu-regeln-jeder-soll-handy-akkus-tauschen-koennen-a-06ae1024-8fbf-44c5-a420-70be35c1a401 |archive-date=2022-12-11}}</ref>

== See also ==
{{Portal|Energy|Renewable energy|Electronics}}

* [[Battery simulator]]
* [[Nanowire battery]]
* [[Thermal energy storage]]
* [[Battery contact bouncing]]
* ''[[Search for the Super Battery]]''

== References ==

{{refs}}

== Bibliography ==
* {{cite book|last=Dingrando|first=Laurel|title=Chemistry: Matter and Change|year=2007|publisher=Glencoe/McGraw-Hill|location=New York|isbn=978-0-07-877237-5|display-authors=etal}} Ch. 21 (pp.&nbsp;662–695) is on electrochemistry.
* {{cite book|last=Fink|first=Donald G.|author-link=Donald G. Fink |author2=H. Wayne Beaty| title=Standard Handbook for Electrical Engineers, Eleventh Edition|year=1978| publisher=McGraw-Hill|location=New York|isbn=978-0-07-020974-9}}
* {{cite book|last=Knight|first=Randall D.|title=Physics for Scientists and Engineers: A Strategic Approach|year=2004|publisher=Pearson Education|location=San Francisco|isbn=978-0-8053-8960-9|url=https://archive.org/details/physicsforscien200knig}} Chs. 28–31 (pp.&nbsp;879–995) contain information on electric potential.
* {{cite book|last=Linden|first=David|author2=Thomas B. Reddy|title=Handbook of Batteries|year=2001|publisher=McGraw-Hill|location=New York|isbn=978-0-07-135978-8|url=https://archive.org/details/handbookofbatter0000unse}}
* {{cite book|last=Saslow|first=Wayne M.|title=Electricity, Magnetism, and Light|year=2002|publisher=Thomson Learning|location=Toronto|isbn=978-0-12-619455-5}} Chs. 8–9 (pp.&nbsp;336–418) have more information on batteries.
* Turner, James Morton. ''Charged: A History of Batteries and Lessons for a Clean Energy Future'' (University of Washington Press, 2022). [http://www.h-net.org/reviews/showrev.php?id=58799 online review]

== External links ==
* {{Commons category-inline}}
* {{curlie|Business/Electronics_and_Electrical/Power_Supplies/Batteries/|Batteries}}
* [https://web.archive.org/web/20131022104620/http://electrochem.cwru.edu/encycl/art-b02-batt-nonr.htm Non-rechargeable batteries] (archived 22 October 2013)
* [http://electronics.howstuffworks.com/battery.htm HowStuffWorks: How batteries work]
* [http://depts.washington.edu/matseed/batteries/MSE/classification.html Other Battery Cell Types]
* [http://www.doitpoms.ac.uk/tlplib/batteries/index.php DoITPoMS Teaching and Learning Package- "Batteries"]

{{Battery sizes}}
{{Galvanic cells}}
{{Footer energy}}

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[[Category:Battery (electricity)| ]]
[[Category:Italian inventions]]
[[Category:Electric power]]
[[Category:Consumer electronics]]
[[Category:18th-century inventions]]