Editing Lithium (section)

== Applications ==
[[File:Lithium Uses Chart 2020.png|thumb|Pie chart of how much lithium was used and in what way globally in 2020.<ref>{{cite web |title=Lithium |url=https://pubs.usgs.gov/periodicals/mcs2020/mcs2020-lithium.pdf |website=USGS |access-date=15 November 2020 |archive-date=1 November 2020 |archive-url=https://web.archive.org/web/20201101085310/https://pubs.usgs.gov/periodicals/mcs2020/mcs2020-lithium.pdf |url-status=live}}</ref>]]

=== Batteries ===
In 2021, most lithium is used to make [[lithium-ion batteries]] for [[electric car]]s and [[mobile device]]s.

=== Ceramics and glass ===
Lithium oxide is widely used as a [[Flux (metallurgy)|flux]] for processing [[silica]], reducing the [[melting point]] and [[viscosity]] of the material and leading to [[ceramic glaze|glazes]] with improved physical properties including low coefficients of thermal expansion. Worldwide, this is one of the largest use for lithium compounds.<ref name="Li-uses-2011">{{Cite news |url=https://minerals.usgs.gov/minerals/pubs/commodity/lithium/mcs-2016-lithi.pdf |title=Lithium |date=2016 |via=US Geological Survey (USGS) |access-date=29 November 2016 |url-status=live |archive-url=https://web.archive.org/web/20161130163912/http://minerals.usgs.gov/minerals/pubs/commodity/lithium/mcs-2016-lithi.pdf |archive-date=30 November 2016}}</ref><ref>{{Cite web |url=http://www.fmclithium.com/Portals/FMCLithiumFineChemicals/Content/Docs/Worldwide+Demand+by+Sector.pdf |archive-url=https://web.archive.org/web/20140907204758/http://www.fmclithium.com/Portals/FMCLithiumFineChemicals/Content/Docs/Worldwide%20Demand%20by%20Sector.pdf |title=Fmclithium.com |archive-date=7 September 2014 |website=www.fmclithium.com}}</ref> Glazes containing lithium oxides are used for ovenware. [[Lithium carbonate]] (Li<sub>2</sub>CO<sub>3</sub>) is generally used in this application because it converts to the oxide upon heating.<ref>{{cite web |url=http://www.chemguide.co.uk/inorganic/group1/compounds.html |title=Some Compounds of the Group 1 Elements |last1=Clark |first1=Jim |date=2005 |website=chemguide.co.uk |access-date=8 August 2013 |archive-url=https://web.archive.org/web/20130627011258/http://www.chemguide.co.uk/inorganic/group1/compounds.html |archive-date=27 June 2013}}</ref>

=== Electrical and electronic ===
Late in the 20th century, lithium became an important component of battery electrolytes and electrodes, because of its high [[electrode potential]]. Because of its low [[atomic mass]], it has a high charge- and [[power-to-weight ratio]]. A typical [[lithium-ion battery]] can generate approximately 3 [[volt]]s per cell, compared with 2.1 volts for [[lead–acid battery|lead-acid]] and 1.5 volts for [[zinc-carbon cell|zinc-carbon]]. Lithium-ion batteries, which are rechargeable and have a high [[energy density]], differ from [[lithium metal batteries]], which are [[disposable]] ([[primary cell|primary]]) [[Battery (electricity)|batteries]] with lithium or its compounds as the [[anode]].<ref>{{cite web |url=http://www.batteryreview.org/disposable-batteries.html |title=Disposable Batteries – Choosing between Alkaline and Lithium Disposable Batteries |publisher=Batteryreview.org |access-date=10 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20140106031920/http://www.batteryreview.org/disposable-batteries.html |archive-date=6 January 2014}}</ref><ref>{{cite web |url=http://www.emc2.cornell.edu/content/view/battery-anodes.html |title=Battery Anodes > Batteries & Fuel Cells > Research > The Energy Materials Center at Cornell |publisher=Emc2.cornell.edu |access-date=10 October 2013 |url-status=live |archive-url=https://web.archive.org/web/20131222234030/http://www.emc2.cornell.edu/content/view/battery-anodes.html |archive-date=22 December 2013}}</ref> Other rechargeable batteries that use lithium include the [[lithium-ion polymer battery]], [[lithium iron phosphate battery]], and the [[nanowire battery]].

Over the years opinions have been differing about potential growth. A 2008 study concluded that "realistically achievable lithium carbonate production would be sufficient for only a small fraction of future [[PHEV]] and [[electric vehicle|EV]] global market requirements", that "demand from the portable electronics sector will absorb much of the planned production increases in the next decade", and that "mass production of lithium carbonate is not environmentally sound, it will cause irreparable ecological damage to ecosystems that should be protected and that [[LiIon]] propulsion is incompatible with the notion of the 'Green Car'".<ref name="meridian" />

=== Lubricating greases ===
{{Main|Lithium grease}}
The third most common use of lithium is in greases. Lithium hydroxide is a strong [[base (chemistry)|base]], and when heated with a fat, it produces a soap, such as [[lithium stearate]] from [[stearic acid]]. Lithium soap has the ability to [[thickening agent|thicken]] oils, and it is used to manufacture all-purpose, high-temperature [[grease (lubricant)|lubricating greases]].<ref name="CRC" /><ref>{{Cite book |url={{google books |plainurl=y |id=J_AkNu-Y1wQC |page=559}} |page=559 |title=Fuels and lubricants handbook: technology, properties, performance, and testing |volume=1 |author=Totten, George E. |author2=Westbrook, Steven R. |author3=Shah, Rajesh J. |name-list-style=amp |publisher=ASTM International |date=2003 |isbn=978-0-8031-2096-9 |url-status=live |archive-url=https://web.archive.org/web/20160723033807/https://books.google.com/books?id=J_AkNu-Y1wQC&pg=PA559 |archive-date=23 July 2016}}</ref><ref>{{cite book |pages=150–152 |url={{google books |plainurl=y |id=3FkMrP4Hlw0C |page=152}} |title=Significance of tests for petroleum products |author=Rand, Salvatore J. |publisher=ASTM International |date=2003 |isbn=978-0-8031-2097-6 |url-status=live |archive-url=https://web.archive.org/web/20160731221639/https://books.google.com/books?id=3FkMrP4Hlw0C&pg=PA152 |archive-date=31 July 2016}}</ref>

=== Metallurgy ===
Lithium (e.g. as lithium carbonate) is used as an additive to [[continuous casting]] mould flux slags where it increases fluidity,<ref>{{citation |title=The Theory and Practice of Mold Fluxes Used in Continuous Casting: A Compilation of Papers on Continuous Casting Fluxes Given at the 61st and 62nd Steelmaking Conference |publisher=Iron and Steel Society}}</ref><ref>{{Cite journal |doi=10.4028/www.scientific.net/MSF.675-677.877 |title=Effects of Li<sub>2</sub>CO<sub>3</sub> on Properties of Mould Flux for High Speed Continuous Casting |journal=Materials Science Forum |volume=675–677 |pages=877–880 |year=2011 |last1=Lu |first1=Y. Q. |last2=Zhang |first2=G. D. |last3=Jiang |first3=M. F. |last4=Liu |first4=H. X. |last5=Li |first5=T. |s2cid=136666669}}</ref> a use which accounts for 5% of global lithium use (2011).<ref name="minerals.usgs.gov" /> Lithium compounds are also used as additives (fluxes) to [[foundry sand]] for iron casting to reduce veining.<ref>{{citation |url=http://www.afsinc.org/multimedia/contentMC.cfm?ItemNumber=16784 |title=Testing 1-2-3: Eliminating Veining Defects |work=Modern Casting |date=July 2014 |archive-url=https://web.archive.org/web/20150402163428/http://www.afsinc.org/multimedia/contentMC.cfm?ItemNumber=16784 |archive-date=2 April 2015 |access-date=15 March 2015}}</ref>

Lithium (as [[lithium fluoride]]) is used as an additive to aluminium smelters ([[Hall–Héroult process]]), reducing melting temperature and increasing electrical resistance,<ref>{{citation |title=Chemical and Physical Properties of the Hall-Héroult Electrolyte |first=W. |last=Haupin |page=449 |work=Molten Salt Chemistry: An Introduction and Selected Applications |editor-first=Gleb |editor-last=Mamantov |editor-first2=Roberto |editor-last2=Marassi |publisher=Springer |date=1987}}</ref> a use which accounts for 3% of production (2011).<ref name="minerals.usgs.gov" />

When used as a [[flux (metallurgy)|flux]] for [[welding]] or [[soldering]], metallic lithium promotes the fusing of metals during the process<ref>{{Cite book |url={{google books |plainurl=y |id=Ua2SVcUBHZgC}} |title=Handbook of Lithium and Natural Calcium Chloride |last=Garrett |first=Donald E. |date=2004-04-05 |publisher=Academic Press |isbn=978-0-08-047290-4 |page=200 |language=en |url-status=live |archive-url=https://web.archive.org/web/20161203191847/https://books.google.com/books?id=Ua2SVcUBHZgC |archive-date=3 December 2016}}</ref> and eliminates the formation of [[oxide]]s by absorbing impurities.<ref>{{Cite book |url={{google books |plainurl=y |id=OG7PzP5xiHwC |page=171}} |title=Aluminum-Lithium Alloys: Processing, Properties, and Applications |last1=Prasad |first1=N. Eswara |last2=Gokhale |first2=Amol |last3=Wanhill |first3=R. J. H. |date=2013-09-20 |publisher=Butterworth-Heinemann |isbn=978-0-12-401679-8 |language=en |access-date=6 November 2020 |archive-date=1 January 2021 |archive-url=https://web.archive.org/web/20210101021730/https://books.google.com/books?id=OG7PzP5xiHwC&q=metallic+lithium+flux+removes+impurities&pg=PA171 |url-status=live}}</ref> [[Alloy]]s of the metal with aluminium, [[cadmium]], copper and [[manganese]] are used to make high-performance, low density aircraft parts (see also [[Al-Li|Lithium-aluminium alloys]]).<ref>{{cite book |author1=Davis, Joseph R. ASM International. Handbook Committee |title=Aluminum and aluminum alloys |url={{google books |plainurl=y |id=Lskj5k3PSIcC |page=121}} |access-date=16 May 2011 |date=1993 |publisher=ASM International |isbn=978-0-87170-496-2 |pages=121– |url-status=live |archive-url=https://web.archive.org/web/20130528093207/http://books.google.com/books?id=Lskj5k3PSIcC&pg=PA121 |archive-date=28 May 2013}}</ref>

=== Silicon nano-welding ===
Lithium has been found effective in assisting the perfection of silicon nano-welds in electronic components for electric batteries and other devices.<ref>{{cite journal |last1=Karki |first1=Khim |last2=Epstein |first2=Eric |last3=Cho |first3=Jeong-Hyun |last4=Jia |first4=Zheng |last5=Li |first5=Teng |last6=Picraux |first6=S. Tom |last7=Wang |first7=Chunsheng |last8=Cumings |first8=John |title=Lithium-Assisted Electrochemical Welding in Silicon Nanowire Battery Electrodes |journal=Nano Letters |volume=12 |issue=3 |pages=1392–7 |year=2012 |pmid=22339576 |doi=10.1021/nl204063u |bibcode=2012NanoL..12.1392K |url=http://terpconnect.umd.edu/~lit/publications/TengLi-Pub43-NL-2012.pdf |url-status=live |archive-url=https://web.archive.org/web/20170810065805/http://terpconnect.umd.edu/~lit/publications/TengLi-Pub43-NL-2012.pdf |archive-date=10 August 2017}}</ref>

[[File:FlammenfärbungLi.png|thumb|upright=0.4|Lithium is used in flares and [[pyrotechnics]] is due to its rose-red flame.<ref>{{cite journal |last1=Koch |first1=Ernst-Christian |title=Special Materials in Pyrotechnics: III. Application of Lithium and its Compounds in Energetic Systems |journal=Propellants, Explosives, Pyrotechnics |volume=29 |issue=2 |year=2004 |pages=67–80 |doi=10.1002/prep.200400032}}</ref>]]

=== Pyrotechnics ===
Lithium compounds are used as [[pyrotechnic colorant]]s and oxidizers in red [[fireworks]] and [[Flare (pyrotechnic)|flares]].<ref name="CRC" /><ref>{{Cite book |chapter-url=https://books.google.com/books?id=Mtth5g59dEIC&pg=PA1089 |chapter=1.2.1 Inorganic Lithium Compounds [2] |title=Inorganic Chemistry |isbn=978-0-12-352651-9 |access-date=22 February 2016 |archive-date=19 January 2023 |archive-url=https://web.archive.org/web/20230119063602/https://books.google.com/books?id=Mtth5g59dEIC&pg=PA1089 |url-status=dead |editor-last1=Wiberg |editor-first1=Egon |editor-last2=Wiberg |editor-first2=Nils |editor-last3=Holleman |editor-first3=Arnold Frederick |year=2001 |publisher=Academic Press |page=1089}}</ref>

=== Air purification ===
[[Lithium chloride]] and [[lithium bromide]] are [[hygroscopic]] and are used as [[desiccant]]s for gas streams.<ref name="CRC" /> Lithium hydroxide and [[lithium peroxide]] are the salts most commonly used in confined areas, such as aboard [[spacecraft]] and [[submarine]]s, for carbon dioxide removal and air purification. Lithium hydroxide absorbs [[carbon dioxide]] from the air by forming lithium carbonate, and is preferred over other alkaline hydroxides for its low weight.

Lithium peroxide (Li<sub>2</sub>O<sub>2</sub>) in presence of moisture not only reacts with carbon dioxide to form lithium carbonate, but also releases oxygen.<ref>{{cite book |chapter=Air Quality Systems for Related Enclosed Spaces: Spacecraft Air |author=Mulloth, L.M. |author2=Finn, J.E. |name-list-style=amp |title=The Handbook of Environmental Chemistry |date=2005 |volume=4H |pages=383–404 |doi=10.1007/b107253 |isbn=978-3-540-25019-7}}</ref><ref>{{cite web |url=http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0619497 |title=Application of lithium chemicals for air regeneration of manned spacecraft |publisher=Lithium Corporation of America & Aerospace Medical Research Laboratories |date=1965 |archive-url=https://web.archive.org/web/20121007040028/http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0619497 |archive-date=7 October 2012}}</ref> The reaction is as follows:
:2 Li<sub>2</sub>O<sub>2</sub> + 2 CO<sub>2</sub> → 2 Li<sub>2</sub>CO<sub>3</sub> + O<sub>2</sub>
Some of the aforementioned compounds, as well as [[lithium perchlorate]], are used in [[Chemical oxygen generator#Oxygen candle|oxygen candles]] that supply [[submarine]]s with [[oxygen]]. These can also include small amounts of [[boron]], [[magnesium]], [[aluminium]], [[silicon]], [[titanium]], [[manganese]], and [[iron]].<ref>{{cite journal |last1=Markowitz |first1=M. M. |last2=Boryta |first2=D. A. |last3=Stewart |first3=Harvey |title=Lithium Perchlorate Oxygen Candle. Pyrochemical Source of Pure Oxygen |journal=Industrial & Engineering Chemistry Product Research and Development |volume=3 |issue=4 |year=1964 |pages=321–30 |doi=10.1021/i360012a016}}</ref>

=== Optics ===
[[Lithium fluoride]], artificially grown as [[crystal]], is clear and transparent and often used in specialist optics for [[infrared|IR]], [[ultraviolet|UV]] and VUV ([[vacuum UV]]) applications. It has one of the lowest [[refractive index|refractive indices]] and the furthest transmission range in the deep UV of most common materials.<ref>{{Cite book |url={{google books |plainurl=y |id=CQ5uKN_MN2gC |page=149}} |page=149 |title=Building Electro-Optical Systems: Making It All Work |author=Hobbs, Philip C. D. |publisher=John Wiley and Sons |date=2009 |isbn=978-0-470-40229-0 |url-status=live |archive-url=https://web.archive.org/web/20160623202135/https://books.google.com/books?id=CQ5uKN_MN2gC&pg=PA149 |archive-date=23 June 2016}}</ref> Finely divided lithium fluoride powder has been used for [[Thermoluminescent Dosimeter|thermoluminescent radiation dosimetry]] (TLD): when a sample of such is exposed to radiation, it accumulates [[crystal defect]]s which, when heated, resolve via a release of bluish light whose intensity is proportional to the [[absorbed dose]], thus allowing this to be quantified.<ref>{{Cite book |publisher=World Scientific |url={{google books |plainurl=y |id=FY7s7pPSPtgC |page=819}} |title=Point Defects in Lithium Fluoride Films Induced by Gamma Irradiation |page=819 |series=Proceedings of the 7th International Conference on Advanced Technology & Particle Physics: (ICATPP-7): Villa Olmo, Como, Italy |date=2002 |volume=2001 |isbn=978-981-238-180-4 |url-status=live |archive-url=https://web.archive.org/web/20160606154252/https://books.google.com/books?id=FY7s7pPSPtgC&pg=PA819 |archive-date=6 June 2016}}</ref> Lithium fluoride is sometimes used in focal lenses of [[telescope]]s.<ref name="CRC" /><ref>{{Cite journal |last1=Sinton |first1=William M. |title=Infrared Spectroscopy of Planets and Stars |journal=Applied Optics |volume=1 |page=105 |date=1962 |doi=10.1364/AO.1.000105 |bibcode=1962ApOpt...1..105S |issue=2}}</ref>

The high non-linearity of [[lithium niobate]] also makes it useful in [[nonlinear optics|non-linear optics applications]]. It is used extensively in telecommunication products such as mobile phones and [[optical modulator]]s, for such components as [[crystal oscillator|resonant crystals]]. Lithium applications are used in more than 60% of mobile phones.<ref>{{cite web |url=http://nl.computers.toshiba-europe.com/Contents/Toshiba_nl/NL/WHITEPAPER/files/TISBWhitepapertech.pdf |title=You've got the power: the evolution of batteries and the future of fuel cells |publisher=Toshiba |access-date=17 May 2009 |url-status=live |archive-url=https://web.archive.org/web/20110717075300/http://nl.computers.toshiba-europe.com/Contents/Toshiba_nl/NL/WHITEPAPER/files/TISBWhitepapertech.pdf |archive-date=17 July 2011}}</ref>

=== Organic and polymer chemistry ===
[[Organolithium compound]]s are widely used in the production of polymer and fine-chemicals. In the polymer industry, which is the dominant consumer of these reagents, alkyl lithium compounds are [[catalyst]]s/[[radical initiator|initiators]]<ref>{{cite web |url=http://chemical.ihs.com/CEH/Public/Reports/681.7000/ |title=Organometallics |work=IHS Chemicals |date=February 2012 |access-date=2 January 2012 |archive-url=https://archive.today/20120707175638/http://chemical.ihs.com/CEH/Public/Reports/681.7000/ |archive-date=7 July 2012 |url-status=live}}</ref> in [[Anionic addition polymerization|anionic polymerization]] of [[functional group|unfunctionalized]] [[olefin]]s.<ref>{{Cite journal |title=Polymerization of 1,2-dimethylenecyclobutane by organolithium initiators |journal=Russian Chemical Bulletin |volume=37 |date=2005 |doi=10.1007/BF00962487 |pages=1782–1784 |author=Yurkovetskii, A. V. |first2=V. L. |first3=K. L. |last2=Kofman |last3=Makovetskii |issue=9 |s2cid=94017312}}</ref><ref>{{Cite journal |doi=10.1021/ma00159a001 |title=Functionalization of polymeric organolithium compounds. Amination of poly(styryl)lithium |date=1986 |author=Quirk, Roderic P. |journal=Macromolecules |volume=19 |pages=1291–1294 |first2=Pao Luo |last2=Cheng |bibcode=1986MaMol..19.1291Q |issue=5}}</ref><ref>{{Cite book |title=Advances in organometallic chemistry |author=Stone, F. G. A. |author2=West, Robert |publisher=Academic Press |date=1980 |isbn=978-0-12-031118-7 |page=55 |url={{google books |plainurl=y |id=_gai4kRfcMUC}} |access-date=6 November 2020 |archive-date=13 March 2021 |archive-url=https://web.archive.org/web/20210313170549/https://books.google.com/books?id=_gai4kRfcMUC |url-status=live}}</ref> For the production of fine chemicals, organolithium compounds function as strong bases and as reagents for the formation of [[carbon-carbon bond]]s. Organolithium compounds are prepared from lithium metal and [[alkyl halide]]s.<ref>{{Cite book |url={{google books |plainurl=y |id=_SJ2upYN6DwC |page=192}} |page=192 |title=Synthetic approaches in organic chemistry |author=Bansal, Raj K. |date=1996 |publisher=Jones & Bartlett Learning |isbn=978-0-7637-0665-4 |url-status=live |archive-url=https://web.archive.org/web/20160618033923/https://books.google.com/books?id=_SJ2upYN6DwC&pg=PA192 |archive-date=18 June 2016}}</ref>

Many other lithium compounds are used as reagents to prepare organic compounds. Some popular compounds include [[lithium aluminium hydride]] (LiAlH<sub>4</sub>), [[lithium triethylborohydride]], [[N-Butyllithium|''n''-butyllithium]] and [[Tert-Butyllithium|''tert''-butyllithium]].

[[File:US Navy 040626-N-5319A-006 An Anti-Submarine Warfare (ASW) MK-50 Torpedo is launched from guided missile destroyer USS Bulkeley (DDG 84).jpg|thumb|The launch of a torpedo using lithium as fuel]]

=== Military ===
Metallic lithium and its complex [[hydride]]s, such as lithium aluminium hydride (LiAlH<sub>4</sub>), are used as high-energy additives to [[rocket propellant]]s.<ref name="emsley" /> LiAlH<sub>4</sub> can also be used by itself as a [[solid fuel]].<ref>{{Cite web |title=An Experimental Investigation of a Lithium Aluminum Hydride–Hydrogen Peroxide Hybrid Rocket |url=http://media.armadilloaerospace.com/misc/LiAl-Hydride.pdf |archive-url=https://web.archive.org/web/20030628230627/http://media.armadilloaerospace.com/misc/LiAl-Hydride.pdf |archive-date=28 June 2003 |date=28 June 2003}}</ref>

The [[Mark 50 torpedo]] stored chemical energy propulsion system (SCEPS) uses a small tank of [[sulfur hexafluoride]], which is sprayed over a block of solid lithium. The reaction generates heat, creating [[steam]] to propel the torpedo in a closed [[Rankine cycle]].<ref>{{Cite journal |title=Stored Chemical Energy Propulsion System for Underwater Applications |author=Hughes, T.G. |author2=Smith, R.B. |author3=Kiely, D.H. |name-list-style=amp |journal=Journal of Energy |date=1983 |volume=7 |issue=2 |pages=128–133 |doi=10.2514/3.62644 |bibcode=1983JEner...7..128H}}</ref>

[[Lithium hydride]] containing lithium-6 is used in [[thermonuclear weapon]]s, where it serves as fuel for the fusion stage of the bomb.<ref>{{cite book |last=Emsley |first=John |title=Nature's Building Blocks |date=2011}}</ref>

=== Nuclear ===
Lithium-6 is valued as a source material for [[tritium]] production and as a [[neutron absorber]] in [[nuclear fusion]]. Natural lithium contains about 7.5% lithium-6 from which large amounts of lithium-6 have been produced by [[isotope separation]] for use in [[nuclear weapon]]s.<ref>{{cite book |pages=59–60 |url={{google books |plainurl=y |id=0oa1vikB3KwC |page=60}} |title=Nuclear Wastelands: A Global Guide to Nuclear Weapons Production and Its Health and Environmental Effects |author=Makhijani, Arjun |author2=Yih, Katherine |name-list-style=amp |publisher=MIT Press |date=2000 |isbn=978-0-262-63204-1 |url-status=live |archive-url=https://web.archive.org/web/20160613234841/https://books.google.com/books?id=0oa1vikB3KwC&pg=PA60 |archive-date=13 June 2016}}</ref> Lithium-7 gained interest for use in [[nuclear reactor]] [[coolant]]s.<ref>{{cite book |url={{google books |plainurl=y |id=iRI7Cx2D4e4C |page=278}} |page=278 |title=Nuclear wastes: technologies for separations and transmutation |publisher=National Academies Press |date=1996 |isbn=978-0-309-05226-9 |author=National Research Council (U.S.). Committee on Separations Technology and Transmutation Systems |url-status=live |archive-url=https://web.archive.org/web/20160613113140/https://books.google.com/books?id=iRI7Cx2D4e4C&pg=PA278 |archive-date=13 June 2016}}</ref>

[[File:Castle Bravo Blast.jpg|thumb|Lithium deuteride was used as fuel in the [[Castle Bravo]] nuclear device.]]
[[Lithium deuteride]] was the [[nuclear fusion|fusion fuel]] of choice in early versions of the [[Nuclear weapon|hydrogen bomb]]. When bombarded by [[neutron]]s, both <sup>6</sup>Li and <sup>7</sup>Li produce [[tritium]] — this reaction, which was not fully understood when [[Teller-Ulam design|hydrogen bombs]] were first tested, was responsible for the runaway yield of the [[Castle Bravo]] [[nuclear test]]. Tritium fuses with [[deuterium]] in a [[Nuclear fusion|fusion]] reaction that is relatively easy to achieve. Although details remain secret, lithium-6 deuteride apparently still plays a role in modern [[nuclear weapons]] as a fusion material.<ref>{{Cite book |url={{google books |plainurl=y |id=yTIOAAAAQAAJ |page=39}} |page=39 |title=How nuclear weapons spread: nuclear-weapon proliferation in the 1990s |author=Barnaby, Frank |publisher=Routledge |date=1993 |isbn=978-0-415-07674-6 |url-status=live |archive-url=https://web.archive.org/web/20160609210558/https://books.google.com/books?id=yTIOAAAAQAAJ&pg=PA39 |archive-date=9 June 2016}}</ref>

[[Lithium fluoride]], when highly enriched in the lithium-7 isotope, forms the basic constituent of the fluoride salt mixture LiF-[[beryllium fluoride|BeF<sub>2</sub>]] used in [[molten salt reactor|liquid fluoride nuclear reactors]]. Lithium fluoride is exceptionally chemically stable and LiF-BeF<sub>2</sub> mixtures have low melting points. In addition, <sup>7</sup>Li, Be, and F are among the few [[nuclide]]s with low enough [[neutron cross-section|thermal neutron capture cross-sections]] not to poison the fission reactions inside a nuclear fission reactor.<ref group=note>Beryllium and fluorine occur only as one isotope, <sup>9</sup>Be and <sup>19</sup>F respectively. These two, together with <sup>7</sup>Li, as well as [[deuterium|<sup>2</sup>H]], <sup>11</sup>B, <sup>15</sup>N, <sup>209</sup>Bi, and the stable isotopes of C, and O, are the only nuclides with low enough thermal neutron capture cross sections aside from [[actinide]]s to serve as major constituents of a molten salt breeder reactor fuel.</ref><ref>{{cite journal |last1=Baesjr |first1=C. |title=The chemistry and thermodynamics of molten salt reactor fuels |journal=Journal of Nuclear Materials |volume=51 |issue=1 |pages=149–162 |date=1974 |doi=10.1016/0022-3115(74)90124-X |bibcode=1974JNuM...51..149B |url=https://digital.library.unt.edu/ark:/67531/metadc1028644/ |osti=4470742 |access-date=28 June 2019 |archive-date=13 March 2021 |archive-url=https://web.archive.org/web/20210313170619/https://digital.library.unt.edu/ark:/67531/metadc1028644/ |url-status=live}}</ref>

In conceptualized (hypothetical) nuclear [[fusion power]] plants, lithium will be used to produce tritium in [[Magnetic confinement fusion|magnetically confined reactors]] using [[deuterium]] and [[tritium]] as the fuel. Naturally occurring tritium is extremely rare and must be synthetically produced by surrounding the reacting [[Plasma (physics)|plasma]] with a 'blanket' containing lithium, where neutrons from the deuterium-tritium reaction in the plasma will fission the lithium to produce more tritium:
:<sup>6</sup>Li + n → <sup>4</sup>He + <sup>3</sup>H.

Lithium is also used as a source for [[alpha particle]]s, or [[helium]] nuclei. When <sup>7</sup>Li is bombarded by accelerated [[proton]]s <sup>8</sup>[[beryllium|Be]] is formed, which almost immediately undergoes fission to form two alpha particles. This feat, called "splitting the atom" at the time, was the first fully human-made [[nuclear reaction]]. It was produced by [[John Douglas Cockcroft|Cockroft]] and [[Ernest Walton|Walton]] in 1932.<ref>{{Cite book |url={{google books |plainurl=y |id=XyOBx2R2CxEC |page=139}} |page=139 |title=Nobel Prize Winners in Physics |author=Agarwal, Arun |publisher=APH Publishing |date=2008 |isbn=978-81-7648-743-6 |url-status=live |archive-url=https://web.archive.org/web/20160629143432/https://books.google.com/books?id=XyOBx2R2CxEC&pg=PA139 |archive-date=29 June 2016}}</ref><ref>[http://www-outreach.phy.cam.ac.uk/camphy/cockcroftwalton/cockcroftwalton9_1.htm "'Splitting the Atom': Cockcroft and Walton, 1932: 9. Rays or Particles?"] {{webarchive|url=https://web.archive.org/web/20120902195556/http://www-outreach.phy.cam.ac.uk/camphy/cockcroftwalton/cockcroftwalton9_1.htm |date=2 September 2012 }} Department of Physics, University of Cambridge</ref> Injection of lithium powders is used in fusion reactors to manipulate plasma-material interactions and dissipate energy in the hot thermo-nuclear fusion plasma boundary.<ref>{{Cite web |url=https://phys.org/news/2011-11-lithium.html |title=With lithium, more is definitely better |website=phys.org}}</ref><ref>{{Cite web |url=https://phys.org/news/2021-11-hot-cores-cool-edges-fusion.html |title=Integrating hot cores and cool edges in fusion reactors |website=phys.org |access-date=23 April 2023 |archive-date=29 April 2023 |archive-url=https://web.archive.org/web/20230429103823/https://phys.org/news/2021-11-hot-cores-cool-edges-fusion.html |url-status=live}}</ref>

In 2013, the US [[Government Accountability Office]] said a shortage of lithium-7 critical to the operation of 65 out of 100 American nuclear reactors "places their ability to continue to provide electricity at some risk." The problem stems from the decline of US nuclear infrastructure. The equipment needed to separate lithium-6 from lithium-7 is mostly a cold war leftover. The US shut down most of this machinery in 1963, when it had a huge surplus of separated lithium, mostly consumed during the twentieth century. The report said it would take five years and $10 million to $12 million to reestablish the ability to separate lithium-6 from lithium-7.<ref name="nyt1013" />

Reactors that use lithium-7 heat water under high pressure and transfer heat through heat exchangers that are prone to corrosion. The reactors use lithium to counteract the corrosive effects of [[boric acid]], which is added to the water to absorb excess neutrons.<ref name="nyt1013">{{cite news |url=https://www.nytimes.com/2013/10/09/business/energy-environment/report-says-a-shortage-of-nuclear-fuel-looms.html |title=Report Says a Shortage of Nuclear Ingredient Looms |author=Wald, Matthew L. |date=8 October 2013 |work=The New York Times |url-status=live |archive-url=https://web.archive.org/web/20170701025300/http://www.nytimes.com/2013/10/09/business/energy-environment/report-says-a-shortage-of-nuclear-fuel-looms.html |archive-date=1 July 2017}}</ref>

=== Medicine ===
{{Main|Lithium (medication)}}
Lithium is useful in the treatment of [[bipolar disorder]].<ref name="kean">{{cite book |last=Kean |first=Sam |title=The Disappearing Spoon |url=https://archive.org/details/disappearingspoo0000kean |url-access=registration |date=2011}}</ref> Lithium salts may also be helpful for related diagnoses, such as [[schizoaffective disorder]] and cyclic [[major depressive disorder]]. The active part of these salts is the lithium ion Li<sup>+</sup>.<ref name="kean" /> Lithium may increase the risk of developing [[Ebstein's anomaly|Ebstein's cardiac anomaly]] in infants born to women who take lithium during the first trimester of pregnancy.<ref name="pmid18982835">{{cite journal |author=Yacobi S |author2=Ornoy A |title=Is lithium a real teratogen? What can we conclude from the prospective versus retrospective studies? A review |journal=Isr J Psychiatry Relat Sci |volume=45 |issue=2 |pages=95–106 |date=2008 |pmid=18982835}}</ref>