Lithium is the lightest metal in nature, with a density about half that of water, and it has become the most strategically coveted metal of the new-energy era. Its single largest use is as the core material of lithium-ion batteries: batteries in consumer electronics such as mobile phones, laptops and tablets rely almost entirely on lithium, while the large-format power batteries of electric vehicles and grid-scale energy storage stations have driven the rapid growth of global lithium demand, with a single electric-vehicle battery pack consuming on the order of ten kilograms of lithium. Beyond batteries, lithium-based greases withstand high temperatures and resist water well, and are widely used for long-life lubrication in automobiles, bearings and industrial machinery. In metallurgy, lithium is added as a deoxidizer and degasser to the melting of copper, aluminum and other metals to improve metal quality; adding lithium to glass and ceramics lowers the melting point and coefficient of thermal expansion, yielding heat-resistant cookware and low-expansion glass. In medicine, lithium carbonate is used to treat bipolar disorder (mania). Lithium is chosen for these applications because of its low atomic weight and low electrode potential, which let it store an extraordinarily high amount of electrical energy per unit mass—a property that few other metals can match.
Lithium carbonate (Li2CO3) is the most basic lithium salt and the starting point for almost all lithium products, serving as the feedstock for battery cathode materials, lithium-salt purification and anti-manic pharmaceuticals. Lithium hydroxide (LiOH) is used mainly to manufacture lithium-based greases and is also an important raw material for high-nickel ternary cathode batteries; because it absorbs carbon dioxide strongly, it is also used for air purification in submarines and spacecraft. Lithium chloride (LiCl) is extremely hygroscopic and is used as a desiccant in industrial dehumidification and air-conditioning systems, as well as in molten-salt electrolysis to extract metallic lithium. Spodumene (LiAlSi2O6) is now one of the world's most important lithium ores; the hard-rock lithium mines in Australia and elsewhere mine it primarily, and it is processed by flotation, roasting and acid leaching to yield lithium carbonate, making it, alongside brine from salt lakes, one of the two principal sources of lithium. In addition, lithium bromide (LiBr), thanks to its strong water absorption, is widely used in absorption chillers of large central air-conditioning systems, and together with lithium chloride it forms another stable market for lithium salts in the HVAC industry.
