Литий: қасиеттері, қолданылуы және ерекшеліктері

the chemical element

Lithium is a chemical element; it has symbol Li and atomic number 3. It is a soft, silvery white alkali metal. Under standard conditions, it is the least dense metal and the least dense solid element. Like all alkali metals, lithium is highly reactive and flammable, and must be stored in vacuum, inert atmosphere, or inert liquid such as purified kerosene or mineral oil. It exhibits a metallic luster. It corrodes quickly in air to a dull silvery gray, then black tarnish. It does not occur freely in nature, but occurs mainly as pegmatitic minerals, which were once the main source of lithium. Due to its solubility as an ion, it is present in ocean water and is commonly obtained from brines. Lithium metal is isolated electrolytically from a mixture of lithium chloride and potassium chloride. The nucleus of the lithium atom verges on instability, since the two stable lithium isotopes found in nature have among the lowest binding energies per nucleon of all stable nuclides. Because of its relative nuclear instability, lithium is less common in the solar system than 25 of the first 32 chemical elements even though its nuclei are very light: it is an exception to the trend that heavier nuclei are less common. For related reasons, lithium has important uses in nuclear physics. The transmutation of lithium atoms to helium in 1932 was the first fully human made nuclear reaction, and lithium deuteride serves as a fusion fuel in staged thermonuclear weapons. Lithium and its compounds have several industrial applications, including heat resistant glass and ceramics, lithium grease lubricants, flux additives for iron, steel and aluminium production, lithium metal batteries, and lithium ion batteries. These uses consume more than three quarters of lithium production. Lithium is present in biological systems in trace amounts. It has no established metabolic function. Lithium based drugs are useful as a mood stabilizer and antidepressant in the treatment of mental illness such as bipolar disorder.

The alkali metals are also called the lithium family, after its leading element. Like the other alkali metals (which are sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr)), lithium has a single valence electron that, in the presence of solvents, is easily released to form Li+. Lithium metal is soft enough to be cut with a knife. It is silvery white. In air it oxidizes to lithium oxide. and its boiling point of It is the least dense of all elements that are solids at room temperature; the next lightest solid element (potassium, at 0.862 g/cm3) is more than 60% denser. Apart from helium and hydrogen, as a solid it is less dense than any other element as a liquid, being only two thirds as dense as liquid nitrogen (0.808 g/cm3). Lithium can float on the lightest hydrocarbon oils and is one of only three metals that can float on water, the other two being sodium and potassium. Lithium's coefficient of thermal expansion is twice that of aluminium and almost four times that of iron. Lithium is superconductive below 400 μK at standard pressure and at higher temperatures (more than 9 K) at very high pressures (>20 GPa). At temperatures below 70 K, lithium, like sodium, undergoes diffusionless phase change transformations. At 4.2 K it has a rhombohedral crystal system (with a nine layer repeat spacing); at higher temperatures it transforms to face centered cubic and then body centered cubic. At liquid helium temperatures (4 K) the rhombohedral structure is prevalent. Multiple allotropic forms have been identified for lithium at high pressures. Lithium has a mass specific heat capacity of 3.58 kilojoules per kilogram kelvin, the highest of all solids. Because of this, lithium metal is often used in coolants for heat transfer applications. Both natural isotopes have anomalously low nuclear binding energy per nucleon (compared to the neighboring elements on the periodic table, helium and beryllium); lithium is the only low numbered element that can produce net energy through nuclear fission. The two lithium nuclei have lower binding energies per nucleon than any other stable nuclides other than hydrogen 1, deuterium and helium 3. As a result of this, though very light in atomic weight, lithium is less common in the Solar System than 25 of the first 32 chemical elements. The 6Li isotope is one of only five stable nuclides to have both an odd number of protons and an odd number of neutrons, the other four stable odd odd nuclides being hydrogen 2, boron 10, nitrogen 14, and tantalum 180m. 7Li is one of the primordial elements (or, more properly, primordial nuclides) produced in Big Bang nucleosynthesis. A small amount of both 6Li and 7Li are produced in stars during stellar nucleosynthesis, but it is further "burned" as fast as produced. 7Li can also be generated in carbon stars. Additional small amounts of both 6Li and 7Li may be generated from solar wind, cosmic rays hitting heavier atoms, and from early solar system 7Be radioactive decay. Lithium isotopes fractionate substantially during a wide variety of natural processes, including mineral formation (chemical precipitation), metabolism, and ion exchange. Lithium ions substitute for magnesium and iron in octahedral sites in clay minerals, where 6Li is preferred to 7Li, resulting in enrichment of the light isotope in processes of hyperfiltration and rock alteration. The exotic 11Li is known to exhibit a neutron halo, with 2 neutrons orbiting around its nucleus of 3 protons and 6 neutrons. The process known as laser isotope separation can be used to separate lithium isotopes, in particular 7Li from 6Li. Nuclear weapons manufacture and other nuclear physics applications are a major source of artificial lithium fractionation, with the light isotope 6Li being retained by industry and military stockpiles to such an extent that it has caused slight but measurable change in the 6Li to 7Li ratios in natural sources, such as rivers. This has led to unusual uncertainty in the standardized atomic weight of lithium, since this quantity depends on the natural abundance ratios of these naturally occurring stable lithium isotopes, as they are available in commercial lithium mineral sources. Both stable isotopes of lithium can be laser cooled and were used to produce the first quantum degenerate Bose–Fermi mixture.

Although it was synthesized in the Big Bang, lithium (together with beryllium and boron) is markedly less abundant in the universe than other elements. This is a result of the comparatively low stellar temperatures necessary to destroy lithium, along with a lack of common processes to produce it. According to modern cosmological theory, lithium—in both stable isotopes (lithium 6 and lithium 7)—was one of the three elements synthesized in the Big Bang. Though the amount of lithium generated in Big Bang nucleosynthesis is dependent upon the number of photons per baryon, for accepted values the lithium abundance can be calculated, and there is a "cosmological lithium discrepancy" in the universe: older stars seem to have less lithium than they should, and some younger stars have much more. The lack of lithium in older stars is apparently caused by the "mixing" of lithium into the interior of stars, where it is destroyed, while lithium is produced in younger stars. Although it transmutes into two atoms of helium due to collision with a proton at temperatures above 2.4 million degrees Celsius (most stars easily attain this temperature in their interiors), lithium is more abundant than computations would predict in later generation stars.]] Lithium is also found in brown dwarf substellar objects and certain anomalous orange stars. Because lithium is present in cooler, less massive brown dwarfs, but is destroyed in hotter red dwarf stars, its presence in the stars' spectra can be used in the "lithium test" to differentiate the two, as both are smaller than the Sun. Certain orange stars can also contain a high concentration of lithium. Those orange stars found to have a higher than usual concentration of lithium (such as Centaurus X 4) orbit massive objects—neutron stars or black holes—whose gravity evidently pulls heavier lithium to the surface of a hydrogen helium star, causing more lithium to be observed.

Although lithium is widely distributed on Earth, it does not naturally occur in elemental form due to its high reactivity. The total lithium content of seawater is very large and is estimated as 230 billion tonnes, where the element exists at a relatively constant concentration of 0.14 to 0.25 parts per million (ppm), higher concentrations approaching 7 ppm are found near hydrothermal vents. In keeping with its name, lithium forms a minor part of igneous rocks, with the largest concentrations in granites. Granitic pegmatites also provide the greatest abundance of lithium containing minerals, with spodumene and petalite being the most commercially viable sources. Another source for lithium is hectorite clay, the only active development of which is through the Western Lithium Corporation in the United States. At 20 mg lithium per kg of Earth's crust, lithium is the 25th most abundant element. According to the Handbook of Lithium and Natural Calcium, "Lithium is a comparatively rare element, although it is found in many rocks and some brines, but always in very low concentrations. There are a fairly large number of both lithium mineral and brine deposits but only comparatively few of them are of actual or potential commercial value. Many are very small, others are too low in grade." Chile is estimated (2020) to have the largest reserves by far (9.2 million tonnes), of lithium is in the Salar de Uyuni area of Bolivia, which has 5.4 million tonnes. Other major suppliers include Australia, Argentina and China. As of 2015, the Czech Geological Survey considered the entire Ore Mountains in the Czech Republic as lithium province. Five deposits are registered, one near Cínovec (Dubí) is considered as a potentially economical deposit, with 160 000 tonnes of lithium. In December 2019, Finnish mining company Keliber Oy reported its Rapasaari lithium deposit has estimated proven and probable ore reserves of 5.280 million tonnes. In June 2010, The New York Times reported that American geologists were conducting ground surveys on dry salt lakes in western Afghanistan believing that large deposits of lithium are located there. These estimates are "based principally on old data, which was gathered mainly by the Soviets during their occupation of Afghanistan from 1979–1989". The Department of Defense estimated the lithium reserves in Afghanistan to amount to the ones in Bolivia and dubbed it as a potential "Saudi Arabia of lithium". In Cornwall, England, the presence of brine rich in lithium was well known due to the region's historic mining industry, and private investors have conducted tests to investigate potential lithium extraction in this area.

Petalite (LiAlSi4O10) was discovered in 1800 by the Brazilian chemist and statesman José Bonifácio de Andrada e Silva in a mine on the island of Utö, Sweden. However, it was not until 1817 that Johan August Arfwedson, then working in the laboratory of the chemist Jöns Jakob Berzelius, detected the presence of a new element while analyzing petalite ore. This element formed compounds similar to those of sodium and potassium, though its carbonate and hydroxide were less soluble in water and less alkaline. Berzelius gave the alkaline material the name "lithion/lithina", from the Greek word λιθoς (transliterated as lithos, meaning "stone"), to reflect its discovery in a solid mineral, as opposed to potassium, which had been discovered in plant ashes, and sodium, which was known partly for its high abundance in animal blood. He named the new element "lithium". However, both Arfwedson and Gmelin tried and failed to isolate the pure element from its salts. It was not isolated until 1821, when William Thomas Brande obtained it by electrolysis of lithium oxide, a process that had previously been employed by the chemist Sir Humphry Davy to isolate the alkali metals potassium and sodium. Brande also described some pure salts of lithium, such as the chloride, and, estimating that lithia (lithium oxide) contained about 55% metal, estimated the atomic weight of lithium to be around 9.8 g/mol (modern value ~6.94 g/mol). In 1855, larger quantities of lithium were produced through the electrolysis of lithium chloride by Robert Bunsen and Augustus Matthiessen. The discovery of this procedure led to commercial production of lithium in 1923 by the German company Metallgesellschaft AG, which performed an electrolysis of a liquid mixture of lithium chloride and potassium chloride. Australian psychiatrist John Cade is credited with reintroducing and popularizing the use of lithium to treat mania in 1949. Shortly after, throughout the mid 20th century, lithium's mood stabilizing applicability for mania and depression took off in Europe and the United States. The production and use of lithium underwent several drastic changes in history. The first major application of lithium was in high temperature lithium greases for aircraft engines and similar applications in World War II and shortly after. This use was supported by the fact that lithium based soaps have a higher melting point than other alkali soaps, and are less corrosive than calcium based soaps. The small demand for lithium soaps and lubricating greases was supported by several small mining operations, mostly in the US. The demand for lithium increased dramatically during the Cold War with the production of nuclear fusion weapons. Both lithium 6 and lithium 7 produce tritium when irradiated by neutrons, and are thus useful for the production of tritium by itself, as well as a form of solid fusion fuel used inside hydrogen bombs in the form of lithium deuteride. The US became the prime producer of lithium between the late 1950s and the mid 1980s. At the end, the stockpile of lithium was roughly 42,000 tonnes of lithium hydroxide. The stockpiled lithium was depleted in lithium 6 by 75%, which was enough to affect the measured atomic weight of lithium in many standardized chemicals, and even the atomic weight of lithium in some "natural sources" of lithium ion which had been "contaminated" by lithium salts discharged from isotope separation facilities, which had found its way into ground water. Lithium is used to decrease the melting temperature of glass and to improve the melting behavior of aluminium oxide in the Hall Héroult process. These two uses dominated the market until the middle of the 1990s. After the end of the nuclear arms race, the demand for lithium decreased and the sale of department of energy stockpiles on the open market further reduced prices. With the surge of lithium demand in batteries in the 2000s, new companies have expanded brine isolation efforts to meet the rising demand. It has been argued that lithium will be one of the main objects of geopolitical competition in a world running on renewable energy and dependent on batteries, but this perspective has also been criticised for underestimating the power of economic incentives for expanded production.

Lithium reacts with water easily, but with noticeably less vigor than other alkali metals. The reaction forms hydrogen gas and lithium hydroxide. Because of its reactivity with water, and especially nitrogen, lithium metal is usually stored in a hydrocarbon sealant, often petroleum jelly. Although the heavier alkali metals can be stored under mineral oil, lithium is not dense enough to fully submerge itself in these liquids. The metal reacts with hydrogen gas at high temperatures to produce lithium hydride (LiH). Lithium forms a variety of binary and ternary materials by direct reaction with the main group elements. These Zintl phases, although highly covalent, can be viewed as salts of polyatomic anions such as Si44 , P73 , and Te52 With graphite, lithium forms a variety of intercalation compounds. Thus, these are extremely powerful bases and nucleophiles. They have also been applied in asymmetric synthesis in the pharmaceutical industry. For laboratory organic synthesis, many organolithium reagents are commercially available in solution form. These reagents are highly reactive, and are sometimes pyrophoric. Like its inorganic compounds, almost all organic compounds of lithium formally follow the duet rule (e. g., BuLi, MeLi). However, it is important to note that in the absence of coordinating solvents or ligands, organolithium compounds form dimeric, tetrameric, and hexameric clusters (e. g., BuLi is actually [BuLi]6 and MeLi is actually [MeLi]4) which feature multi center bonding and increase the coordination number around lithium. These clusters are broken down into smaller or monomeric units in the presence of solvents like dimethoxyethane (DME) or ligands like tetramethylethylenediamine (TMEDA). As an exception to the duet rule, a two coordinate lithate complex with four electrons around lithium, [Li(thf)4]+[((Me3Si)3C)2Li]–, has been characterized crystallographically.

The small ionic size makes it difficult for lithium to be included in early stages of mineral crystallization. As a result, lithium remains in the molten phases, where it gets enriched, until it gets solidified in the final stages. Such lithium enrichment is responsible for all commercially promising lithium ore deposits. Brines (and dry salt) are another important source of Li+. Although the number of known lithium containing deposits and brines is large, most of them are either small or have too low Li+ concentrations. Thus, only a few appear to be of commercial value. The US Geological Survey (USGS) estimated worldwide identified lithium reserves in 2020 and 2021 to be 17 million and 21 million tonnes, respectively. An accurate estimate of world lithium reserves is difficult. One reason for this is that most lithium classification schemes are developed for solid ore deposits, whereas brine is a fluid that is problematic to treat with the same classification scheme due to varying concentrations and pumping effects. In 2019, world production of lithium from spodumene was around 80,000t per annum, primarily from the Greenbushes pegmatite and from some Chinese and Chilean sources. The Talison mine in Greenbushes is reported to be the largest and to have the highest grade of ore at 2.4% Li2O (2012 figures).

The world's top four lithium producing countries from 2019, as reported by the US Geological Survey, are Australia, Chile, China and Argentina. Deposits are also found in South America throughout the Andes mountain chain. Chile is the leading producer, followed by Argentina. Both countries recover lithium from brine pools. According to USGS, Bolivia's Uyuni Desert has 5.4 million tonnes of lithium. Half the world's known reserves are located in Bolivia along the central eastern slope of the Andes. The Bolivian government has invested US$900 million in lithium production and in 2021 successfully produced 540 tons. The brines in the salt pans of the Lithium Triangle vary widely in lithium content.

Since 2018 the Democratic Republic of Congo is known to have the largest lithium spodumene hard rock deposit in the world. The deposit located in Manono, DRC, may hold up to 1.5 billion tons of lithium spodumene hard rock. The two largest pegmatites (known as the Carriere de l'Este Pegmatite and the Roche Dure Pegmatite) are each of similar size or larger than the famous Greenbushes Pegmatite in Western Australia. Thus, the Democratic Republic of Congo is expected to be a significant supplier of lithium to the world with its high grade and low impurities. On 16 July 2018 2.5 million tonnes of high grade lithium resources and 124 million pounds of uranium resources were found in the Falchani hard rock deposit in the region Puno, Peru. In 2020, Australia granted Major Project Status (MPS) to the Finniss Lithium Project for a strategically important lithium deposit: an estimated 3.45 million tonnes (Mt) of mineral resource at 1.4 percent lithium oxide. Operational mining began in 2022. A deposit discovered in 2013 in Wyoming's Rock Springs Uplift is estimated to contain 228,000 tons. Additional deposits in the same formation were estimated to be as much as 18 million tons. Similarly in Nevada, the McDermitt Caldera hosts lithium bearing volcanic muds that consist of the largest known deposits of lithium within the United States. The Pampean Pegmatite Province in Argentina is known to have a total of at least 200,000 tons of spodumene with lithium oxide (Li2O) grades varying between 5 and 8 wt %. In Russia the largest lithium deposit Kolmozerskoye is located in Murmansk region. In 2023, Polar Lithium, a joint venture between Nornickel and Rosatom, has been granted the right to develop the deposit. The project aims to produce 45,000 tonnes of lithium carbonate and hydroxide per year and plans to reach full design capacity by 2030.

In 1998, the price of lithium metal was about 95 USD/kg (or US$43/lb). After the 2007 financial crisis, major suppliers, such as Sociedad Química y Minera (SQM), dropped lithium carbonate pricing by 20%. Prices rose in 2012. A 2012 Business Week article outlined an oligopoly in the lithium space: "SQM, controlled by billionaire Julio Ponce, is the second largest, followed by Rockwood, which is backed by Henry Kravis's KKR & Co., and Philadelphia based FMC", with Talison mentioned as the biggest producer. The price information service ISE Institute of Rare Earths Elements and Strategic Metals gives for various lithium substances in the average of March to August 2022 the following kilo prices stable in the course: Lithium carbonate, purity 99.5% min, from various producers between 63 and 72 EUR/kg. Lithium hydroxide monohydrate LiOH 56.5% min, China, at 66 to 72 EUR/kg; delivered South Korea 73 EUR/kg. Lithium metal 99.9% min, delivered China 42 EUR/kg.

Lithium and its compounds were historically isolated and extracted from hard rock but by the 1990s mineral springs, brine pools, and brine deposits had become the dominant source. Most of these were in Chile, Argentina and Bolivia. By early 2021, much of the lithium mined globally comes from either "spodumene, the mineral contained in hard rocks found in places such as Australia and North Carolina" or from the salty brine pumped directly out of the ground, as it is in locations in Chile. In Chile's Salar de Atacama, the lithium concentration in the brine is raised by solar evaporation in a system of ponds. One method for lithium extraction, as well as other valuable minerals, is to process geothermal brine water through an electrolytic cell, located within a membrane. The use of electrodialysis and electrochemical intercalation has been proposed to extract lithium compounds from seawater (which contains lithium at 0.2 parts per million). Ion selective cells within a membrane in principle could collect lithium either by use of electric field or a concentration difference. Lithium extraction can be fatal to aquatic life due to water pollution. It is known to cause surface water contamination, drinking water contamination, respiratory problems, ecosystem degradation and landscape damage. In the United States, open pit mining and mountaintop removal mining compete with brine extraction mining. Environmental concerns include wildlife habitat degradation, potable water pollution including arsenic and antimony contamination, unsustainable water table reduction, and massive mining waste, including radioactive uranium byproduct and sulfuric acid discharge.

A study of relationships between lithium extraction companies and indigenous peoples in Argentina indicated that the state may not have protected indigenous peoples' right to free prior and informed consent, and that extraction companies generally controlled community access to information and set the terms for discussion of the projects and benefit sharing. Development of the Thacker Pass lithium mine in Nevada, United States, has met with protests and lawsuits from several indigenous tribes who have said they were not provided free prior and informed consent and that the project threatens cultural and sacred sites. They have also expressed concerns that development of the project will create risks to indigenous women, because resource extraction is linked to missing and murdered indigenous women. Protestors have been occupying the site of the proposed mine since January 2021.]]

In 2021, most lithium is used to make lithium ion batteries for electric cars and mobile devices.

Lithium oxide is widely used as a flux for processing silica, reducing the melting point and viscosity of the material and leading to glazes with improved physical properties including low coefficients of thermal expansion. Worldwide, this is one of the largest use for lithium compounds. Glazes containing lithium oxides are used for ovenware. Lithium carbonate (Li2CO3) is generally used in this application because it converts to the oxide upon heating.

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 volts per cell, compared with 2.1 volts for lead acid and 1.5 volts for zinc carbon. Lithium ion batteries, which are rechargeable and have a high energy density, differ from lithium metal batteries, which are disposable (primary) batteries with lithium or its compounds as the anode. 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 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'".

Lithium (e. g. as lithium carbonate) is used as an additive to continuous casting mould flux slags where it increases fluidity, a use which accounts for 5% of global lithium use (2011). Lithium (as lithium fluoride) is used as an additive to aluminium smelters (Hall–Héroult process), reducing melting temperature and increasing electrical resistance, a use which accounts for 3% of production (2011). and eliminates the formation of oxides by absorbing impurities. Alloys of the metal with aluminium, cadmium, copper and manganese are used to make high performance, low density aircraft parts (see also Lithium aluminium alloys).

Lithium has been found effective in assisting the perfection of silicon nano welds in electronic components for electric batteries and other devices.

Lithium compounds are used as pyrotechnic colorants and oxidizers in red fireworks and flares.

Lithium fluoride, artificially grown as crystal, is clear and transparent and often used in specialist optics for IR, UV and VUV (vacuum UV) applications. It has one of the lowest refractive indices and the furthest transmission range in the deep UV of most common materials. Finely divided lithium fluoride powder has been used for thermoluminescent radiation dosimetry (TLD): when a sample of such is exposed to radiation, it accumulates crystal defects which, when heated, resolve via a release of bluish light whose intensity is proportional to the absorbed dose, thus allowing this to be quantified. Lithium fluoride is sometimes used in focal lenses of telescopes. The high non linearity of lithium niobate also makes it useful in non linear optics applications. It is used extensively in telecommunication products such as mobile phones and optical modulators, for such components as resonant crystals. Lithium applications are used in more than 60% of mobile phones.

Organolithium compounds 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 catalysts/initiators in anionic polymerization of unfunctionalized olefins. For the production of fine chemicals, organolithium compounds function as strong bases and as reagents for the formation of carbon carbon bonds. Organolithium compounds are prepared from lithium metal and alkyl halides. Many other lithium compounds are used as reagents to prepare organic compounds. Some popular compounds include lithium aluminium hydride (LiAlH4), lithium triethylborohydride, n butyllithium and tert butyllithium.

Metallic lithium and its complex hydrides, such as lithium aluminium hydride (LiAlH4), are used as high energy additives to rocket propellants. 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. Lithium hydride containing lithium 6 is used in thermonuclear weapons, where it serves as fuel for the fusion stage of the bomb.

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 weapons. Lithium 7 gained interest for use in nuclear reactor coolants. Lithium deuteride was the fusion fuel of choice in early versions of the hydrogen bomb. When bombarded by neutrons, both 6Li and 7Li produce tritium — this reaction, which was not fully understood when hydrogen bombs were first tested, was responsible for the runaway yield of the Castle Bravo nuclear test. Tritium fuses with deuterium in a 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. Lithium fluoride, when highly enriched in the lithium 7 isotope, forms the basic constituent of the fluoride salt mixture LiF BeF2 used in liquid fluoride nuclear reactors. Lithium fluoride is exceptionally chemically stable and LiF BeF2 mixtures have low melting points. In addition, 7Li, Be, and F are among the few nuclides with low enough thermal neutron capture cross sections not to poison the fission reactions inside a nuclear fission reactor. In conceptualized (hypothetical) nuclear fusion power plants, lithium will be used to produce tritium in 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 with a 'blanket' containing lithium, where neutrons from the deuterium tritium reaction in the plasma will fission the lithium to produce more tritium:
6Li + n → 4He + 3H. Lithium is also used as a source for alpha particles, or helium nuclei. When 7Li is bombarded by accelerated protons 8Be 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 Cockroft and Walton in 1932. 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. 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.". Castle Bravo first used lithium 7 in the Shrimp, its first device, which weighed only 10 tons, and generated massive nuclear atmospheric contamination of Bikini Atoll. This perhaps accounts for 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.

Lithium is useful in the treatment of bipolar disorder. Lithium salts may also be helpful for related diagnoses, such as schizoaffective disorder and cyclic major depression. The active part of these salts is the lithium ion Li+.

Lithium metal is corrosive and requires special handling to avoid skin contact. Breathing lithium dust or lithium compounds (which are often alkaline) initially irritate the nose and throat, while higher exposure can cause a buildup of fluid in the lungs, leading to pulmonary edema. The metal itself is a handling hazard because contact with moisture produces the caustic lithium hydroxide. Lithium is safely stored in non reactive compounds such as naphtha.