The alkali metals consist of the chemical elements lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). Together with hydrogen they constitute group 1, which lies in the s-block of the periodic table. All alkali metals have their outermost electron in an s-orbital: this shared electron configuration results in their having very similar characteristic properties. Indeed, the alkali metals provide the best example of group trends in properties in the periodic table, with elements exhibiting well-characterised homologous behaviour. This family of elements is also known as the lithium family after its leading 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.
In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as ores using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential. The word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity."
A lithium-ion or Li-ion battery is a type of rechargeable battery that uses the reversible intercalation of Li+ ions into electronically conducting solids to store energy. In comparison with other commercial rechargeable batteries, Li-ion batteries are characterized by higher specific energy, higher energy density, higher energy efficiency, a longer cycle life, and a longer calendar life. Also noteworthy is a dramatic improvement in lithium-ion battery properties after their market introduction in 1991: within the next 30 years, their volumetric energy density increased threefold while their cost dropped tenfold.
A lithium polymer battery, or more correctly, lithium-ion polymer battery, is a rechargeable battery of lithium-ion technology using a polymer electrolyte instead of a liquid electrolyte. Highly conductive semisolid (gel) polymers form this electrolyte. These batteries provide higher specific energy than other lithium battery types. They are used in applications where weight is critical, such as mobile devices, radio-controlled aircraft, and some electric vehicles.
Lithium fluoride is an inorganic compound with the chemical formula LiF. It is a colorless solid that transitions to white with decreasing crystal size. Its structure is analogous to that of sodium chloride, but it is much less soluble in water. It is mainly used as a component of molten salts. Partly because Li and F are both light elements, and partly because F2 is highly reactive, formation of LiF from the elements releases one of the highest energies per mass of reactants, second only to that of BeO.
Antimony pentafluoride is the inorganic compound with the formula SbF5. This colourless, viscous liquid is a strong Lewis acid and a component of the superacid fluoroantimonic acid, formed upon mixing liquid HF with liquid SbF5 in 1:1 ratio. It is notable for its strong Lewis acidity and the ability to react with almost all known compounds.
In materials science, fast ion conductors are solid conductors with highly mobile ions. These materials are important in the area of solid state ionics, and are also known as solid electrolytes and superionic conductors. These materials are useful in batteries and various sensors. Fast ion conductors are used primarily in solid oxide fuel cells. As solid electrolytes they allow the movement of ions without the need for a liquid or soft membrane separating the electrodes. The phenomenon relies on the hopping of ions through an otherwise rigid crystal structure.
Lithium borohydride (LiBH4) is a borohydride and known in organic synthesis as a reducing agent for esters. Although less common than the related sodium borohydride, the lithium salt offers some advantages, being a stronger reducing agent and highly soluble in ethers, whilst remaining safer to handle than lithium aluminium hydride.
Hexafluorophosphate is an anion with chemical formula of [PF6]−. It is an octahedral species that imparts no color to its salts. [PF6]− is isoelectronic with sulfur hexafluoride, SF6, and the hexafluorosilicate dianion, [SiF6]2−, and hexafluoroantimonate [SbF6]−. In this anion, phosphorus has a valence of 5. Being poorly nucleophilic, hexafluorophosphate is classified as a non-coordinating anion.
The dioxygenyl ion, O+
2, is a rarely-encountered oxycation in which both oxygen atoms have a formal oxidation state of +1/2. It is formally derived from oxygen by the removal of an electron:
Lithium hexafluorophosphate is an inorganic compound with the formula LiPF6. It is a white crystalline powder.
Dinitrogen difluoride is a chemical compound with the formula N2F2. It is a gas at room temperature, and was first identified in 1952 as the thermal decomposition product of the fluorine azide. It has the structure F−N=N−F and exists in both cis and trans isomers, as typical for diimides.
Aluminium-ion batteries are a class of rechargeable battery in which aluminium ions serve as charge carriers. Aluminium can exchange three electrons per ion. This means that insertion of one Al3+ is equivalent to three Li+ ions. Thus, since the ionic radii of Al3+ (0.54 Å) and Li+ (0.76 Å) are similar, significantly higher numbers of electrons and Al3+ ions can be accepted by cathodes with little damage. Al has 50 times (23.5 megawatt-hours m-3) the energy density of Li and is even higher than coal.
Fluorine forms a great variety of chemical compounds, within which it always adopts an oxidation state of −1. With other atoms, fluorine forms either polar covalent bonds or ionic bonds. Most frequently, covalent bonds involving fluorine atoms are single bonds, although at least two examples of a higher order bond exist. Fluoride may act as a bridging ligand between two metals in some complex molecules. Molecules containing fluorine may also exhibit hydrogen bonding. Fluorine's chemistry includes inorganic compounds formed with hydrogen, metals, nonmetals, and even noble gases; as well as a diverse set of organic compounds. For many elements the highest known oxidation state can be achieved in a fluoride. For some elements this is achieved exclusively in a fluoride, for others exclusively in an oxide; and for still others the highest oxidation states of oxides and fluorides are always equal.
Research in lithium-ion batteries has produced many proposed refinements of lithium-ion batteries. Areas of research interest have focused on improving energy density, safety, rate capability, cycle durability, flexibility, and reducing cost.
The hexafluoroarsenate anion is a chemical species with formula AsF−6. Hexafluoroarsenate is relatively inert, being the conjugate base of the notional superacid hexafluoroarsenic acid.
Potassium hexafluoroantimonate is an inorganic chemical compound with the chemical formula KSbF6.
Potassium hexafluoroarsenate is an inorganic chemical compound with the chemical formula KAsF6.
Lithium hexafluorosilicate is an inorganic chemical compound with the chemical formula Li2SiF6.
