Two of the most common rechargeable batteries in use today are nickel-metal hydride batteries (NiMH) and lithium-ion batteries. However, comparing them may not be especially useful to most consumers, as lithium-ion batteries are not available in consumer grade sizes, according to energy guru Michael Bluejay.
Many people confuse lithium batteries, which are not rechargeable, with lithium-ion batteries, which are rechargeable. No comparison exists for size AA NiMH batteries and lithium batteries. However, a comparison of the sizes of NiMH and lithium-ion batteries used in manufacturing is possible.
NiMH batteries use hydrogen from rare-earth metals such as lanthanum, according to Electropedia.org. Lithium-ion batteries use lithium, the lightest metal, dissolved in carbon to deliver power. Although the first lithium batteries used pure lithium, most industries have switched to a lithium composite material.
Compared with the traditional alkaline battery, NiMH and lithium-ion rechargeable batteries offer a much higher energy capacity. NiMH can deliver 1,300 to 2,900 milliamperes per hour in a AA battery, depending on the manufacturer, according to Michael Bluejay. Each lithium-ion cell delivers about 1,000 milliamperes per hour. Both kinds are resistant to the "memory effect," where the battery "remembers" less than 100 percent of the charge.
Lithium-ion batteries are only available in the product for their intended use -- usually high-powered electronics, such as laptops -- or they contain special chargers often included with the product, according to Electropedia.org. In addition, they may not offer a cost benefit over alkaline batteries in high-powered applications. NiMH batteries are excellent for most uses, except for smoke detectors and flashlights. NiMH batteries lose about 25 percent of their charge each month. Thus, lithium and lithium-ion batteries are better for emergency equipment.
Industries are switching to lithium-ion batteries, especially in hybrid vehicles, according to the Scientists and Engineers for America Action Fund. Part of this shift has occurred because of the difficulty that businesses find in receiving a license to the NiMH patent. Another reason that hybrid manufacturers give for switching to lithium-ion is its light weight, which increases fuel efficiency.