Batteries, 1977 to 2002

Battery systems have undergone significant improvements over the past 25 years. Older systems have been updated with new materials and constructions. New lithium and nickel systems have been introduced, especially in the rechargeable segment, and have undergone tremendous growth and reached maturity. The technology and applications of the various battery systems are reviewed here, and the status of commercial aqueous and nonaqueous systems updated. NEC first introduced electrochemical capacitors in August 1978 under the trade name Supercapacitor(TM). Electrochemical capacitor technology has evolved from first generation products with low energy density for memory protection applications through several generations of designs to create megajoule-size capacitors for transportation and power quality applications. (C) 2004 The Electrochemical Society.