Abstract

Batteries are precision miniature chemical reactors that convert chemical reaction energy into electrical energy, on demand. Batteries range in size from large house-sized batteries for utility storage down to tablet-sized batteries for hearing aids and paper-thin batteries for memory protection in electronic devices. The electrons involved in the chemical reactions are transferred from the active materials undergoing oxidation to the oxidizing agent by means of an external circuit. The passage of electrons through this external circuit provides the means for control of for the direct energy conversion without going through heat as an intermediate step. The three main types of batteries are primary, secondary, and reserve. The battery voltage is unique for each group of reactants comprising the battery system and is determined by the thermodynamics of the reaction. The criteria for commercial batteries is described. Only a few reactions have the characteristics requisite for use in commercial batteries. The performance of typical commercial and developing battery systems is summarized.