A rechargeable battery technology introduced in 1991 that provides greater charge per pound than nickel metal hydride. In 1993, Toshiba introduced the first notebook in the U.S. with a Li-ion battery. Since then, it has become the most popular battery technology for notebooks, cellphones and other handheld devices. In contrast to nickel-based batteries that require full discharges to keep the battery healthy, lithium ion batteries are better with frequent, shallow discharges before charging again. See lithium polymer and batteries.