Battery

A battery is a source of electric power consisting of one or more electrochemical cells with external connections, converting stored chemical energy directly into electrical energy through a reduction-oxidation reaction: when connected to a device, higher-energy reactants inside the cell convert to lower-energy products, driving electrons from the negative terminal through the external circuit to the positive terminal. Italian physicist Alessandro Volta built the first true electrochemical battery in 1800, the voltaic pile, stacking alternating copper and zinc plates separated by brine-soaked paper to produce a steady, continuous current, the first device of its kind. Batteries are broadly divided into primary batteries, single-use disposable cells such as ordinary alkaline batteries, and secondary batteries, rechargeable types such as lead-acid automotive batteries and lithium-ion cells used in consumer electronics and electric vehicles. Global demand for batteries grew roughly 30 percent a year between 2010 and 2018 as transportation electrification and renewable-energy storage expanded, and batteries today range in scale from tiny button cells for watches to massive grid-connected battery banks that help stabilize electrical networks.