Uses of Lithium
Ceramics and glass
Lithium oxide is a widely used flux for processing silica, reducing the melting point and viscosity of the material and leading to glazes of improved physical properties including low coefficients for thermal expansion.[83] Lithium oxides are a component of ovenware. Worldwide, this is the single largest use for lithium compounds.[82] Lithium carbonate (Li2CO3) is generally used in this application: upon heating it converts to the oxide.[84]
Electrical and electronics
In the later years of the 20th century, owing to its high electrochemical potential, lithium became an important component of the electrolyte and of one of the electrodes in batteries. 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 or 1.5 volts for zinc-carbon cells. Lithium-ion batteries, which are rechargeable and have a high energy density, should not be confused with lithium batteries, which aredisposable (primary) batteries with lithium or its compounds as the anode.[85][86] Other rechargeable batteries that use lithium include the lithium-ion polymer battery, lithium iron phosphate battery, and thenanowire battery.
Lubricating greases
The third most common use of lithium is in greases. Lithium hydroxide is a strong base and, when heated with a fat, produces a soap made of lithium stearate. Lithium soap has the ability to thicken oils, and it is used to manufacture all-purpose, high-temperature lubricating greases.[11][87][88]
Metallurgy
When used as a flux for welding or soldering, metallic lithium promotes the fusing of metals during the process and eliminates the forming of oxides by absorbing impurities. Its fusing quality is also important as a flux for producing ceramics, enamels and glass. Alloys of the metal with aluminium, cadmium, copper and manganese are used to make high-performance aircraft parts (see also Lithium-aluminium alloys).[89]
Other chemical and industrial uses
Pyrotechnics
Lithium compounds are used as pyrotechnic colorants and oxidizers in red fireworks and flares.[11][91]
Air purification[
Lithium chloride and lithium bromide are hygroscopic and are used as desiccants for gas streams.[11] Lithium hydroxide and lithium peroxide are the salts most used in confined areas, such as aboard spacecraft and submarines, 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 (Li2O2) in presence of moisture not only reacts with carbon dioxide to form lithium carbonate, but also releases oxygen.[92][93] The reaction is as follows:
2 Li2O2 + 2 CO2 → 2 Li2CO3 + O2.
Some of the aforementioned compounds, as well as lithium perchlorate, are used in oxygen candles that supply submarines withoxygen. These can also include small amounts of boron, magnesium, aluminum, silicon, titanium, manganese, and iron.[94]
Optics
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 indexes and the farthest transmission range in the deep UV of most common materials.[95] 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.[96] Lithium fluoride is sometimes used in focal lenses oftelescopes.[11][97]
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.[98]
Organic and polymer chemistry
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.[99] in anionic polymerization of unfunctionalized olefins.[100][101][102] 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.[103]
Many other lithium compounds are used as reagents to prepare organic compounds. Some popular compounds include lithium aluminium hydride (LiAlH4), lithium triethylborohydride (LiBH(C2H5)3).
Military applications
Metallic lithium and its complex hydrides, such as Li[AlH4], are used as high energy additives to rocket propellants.[13] Lithium aluminum hydride can also be used by itself as a solid fuel.[104]
The Mark 50 Torpedo stored chemical energy propulsion system (SCEPS) uses a small tank of sulfur hexafluoride gas which is sprayed over a block of solid lithium. The reaction generates heat which is used to generate steam. The steam propels the torpedo in a closed Rankine cycle.[105]
Lithium hydride containing lithium-6 is used in hydrogen bombs. In the bomb, it is placed around the core of anatomic bomb.[106]
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 byisotope separation for use in nuclear weapons.[107] Lithium-7 gained interest for use in nuclear reactorcoolants.[108]
Lithium deuteride was the fusion fuel of choice in early versions of the hydrogen bomb. When bombarded byneutrons, 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 still apparently plays a role in modern nuclear weapons, as a fusion material.[109]
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.[note 3][110]
In conceptualized 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 + 3T.
Lithium is also used as a source for alpha particles, or helium nuclei. When 7Li is bombarded by accelerated protons 8Be is formed, which undergoes fission to form two alpha particles. This feat, called "splitting the atom" at the time, was the first fully man-made nuclear reaction. It was produced byCockroft and Walton in 1932.[111][112] (Nuclear reactions and human-directed nuclear transmutation had been accomplished as early as 1917, but by using natural radioactive bombardment with alpha particles).
In 2013, the US Government Accountability Office said the 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 decay of US nuclear infrastructure. The US shut down most of its machinery in 1963, given a huge surplus, mostly consumed during the twentieth century. The report said it would take five years and $10 million to $12 million.[113]
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.[113]
Medicine
Lithium is useful in the treatment of bipolar disorder.[114] Lithium salts may also be helpful for related diagnoses, such as schizoaffective disorder and cyclicmajor depression. The active part of these salts is the lithium ion Li+.[114] They may increase the risk of developing Ebstein's cardiac anomaly in infants born to women who take lithium during the first trimester of pregnancy.[115]