Energizer Ultimate Lithium AA Batteries, Double A Batteries (8 Pack)

A, or a, is the first letter and the first vowel letter of the Latin alphabet, used in the modern English alphabet, and others worldwide. Its name in English is a (pronounced AY), plural aes.

It is similar in shape to the Ancient Greek letter alpha, from which it derives. The uppercase version consists of the two slanting sides of a triangle, crossed in the middle by a horizontal bar. The lowercase version is often written in one of two forms: the double-storey |a| and single-storey |ɑ|. The latter is commonly used in handwriting and fonts based on it, especially fonts intended to be read by children, and is also found in italic type.

In English, a is the indefinite article, with the alternative form an.

Energizer Holdings, Inc. is an American manufacturer and one of the world's largest manufacturers of batteries, headquartered in St. Louis, Missouri. It produces batteries under the Energizer, Ray-O-Vac, Varta, and Eveready brand names and formerly owned several personal care businesses until it separated that side of the business into a new company called Edgewell Personal Care in 2015.

In January 2018, Energizer announced it was purchasing the global battery and lighting division from Spectrum Brands, which includes the Ray-O-Vac and Varta brands, for $2 billion in cash. This acquisition was finalized in January 2019 after a lengthy regulatory approval process.

Lithium (from Ancient Greek λίθος (líthos) 'stone') 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.