Early 1920s Samuel Ruben approached the P. R. Mallory Company, manufacturer of tungsten filament wire, seeking a piece of equipment he needed for an experiment. This led to a partnership which would last until Philip Rogers Mallory's death in 1975, was the foundation of Duracell International. Ruben's inventions revolutionized battery technology.
WWII Ruben devised the mercury cell, with more capacity and more durable in the harsh climates of wartime theatres like North Africa and the South Pacific than zinc-carbon batteries in torches, mine detectors, and walkie-talkies. P. R. Mallory manufactured millions of mercury cells for the war effort. The Mallory Battery Company was formed shortly thereafter.
1950s Samuel Ruben went on to improve the alkaline manganese battery, making it more compact, durable, and longer lasting than anything before it. At about the same time, Eastman Kodak introduced cameras with a built-in flash unit that required more power than zinc-carbon cells could provide. The cameras needed a new size of battery, the AAA. Mallory made them, and also licensed the technology to others because the company, at that time, had no consumer distribution.
1973 The Duracell "Bunny" was introduced to carry the message that Duracell batteries lasted much longer than zinc-carbon batteries.
2016 Berkshire Hathaway Company acquired Duracell.
Sources of Information
-  Duracell website