An electrochemical device that generates electric current by converting chemical energy to electrical energy. Its essential components are positive and negative electrodes made of more or less electrically conductive materials, a separating medium, and an electrolyte. There are four major types: (1) primary batteries (dry cells), which are not reversible and in which the anode (zinc) is the negative plate and the cathode (graphite) is the positive plate with ammonium chloride as electrolyte; (2) secondary or storage batteries, which are reversible and can be recharged and in which lead sponge is the negative plate (anode) and lead oxide the positive plate (cathode), with sulfuric acid as electrolyte; (3) nuclear and solar cells, or energy converters; and (4) fuel cells. So-called superbatteries of high charge density have been developed using solid electrolytes of lithium-titanium dioxide and trilithium nitride in which lithium atoms are intercalated in the crystal structure.See Dry Cell; Storage Battery; Voltaic Cell; Fuel Cell; Solar Cell; Intercalation Compound.
