Digital cameras have high power requirements, and over time have become smaller, resulting in an ongoing need to develop a battery small enough to fit in the camera and yet able to power it for a reasonable length of time.
Two broad types of batteries are in use for digital cameras.
AA, CR2, or CR-V3 batteries :
The first type of battery for digital cameras conform to an established off-the-shelf form factor, most commonly AA, CR2, or CR-V3 batteries, with AAA batteries in a handful of cameras. The CR2 and CR-V3 batteries are lithium based, and intended for single use. They are also commonly seen in camcorders. AA batteries are the most common; however, the non-rechargeable alkaline batteries supplied with low-end cameras are capable of providing enough power for only a very short time in most cameras. They may serve satisfactorily in cameras that are only occasionally used.
Consumers with more than an occasional need use AA Nickel metal hydride batteries (NiMH) instead, which provide an adequate amount of power and are rechargeable. NIMH batteries do not provide as much power per volume as lithium ion batteries, and they also tend to discharge when not used. To get same power, NiMH Rechargeable battery takes up to two times in volume compare to Li-on Rechargeable Battery, by weight NiMH Rechargeable Battery is three to five times heavier, but by price NiMH Rechargeable Battery is only a half compare to Li-on Rechargeable Battery. Please see Wikipedia: Table of rechargeable battery technologies in Rechargeable battery. They are available in various ampere-hour (Ah) or milli-ampere-hour (mAh) ratings, which affects how long they last in use. Typically mid-range consumer models and some low end cameras use off-the-shelf batteries; only a very few DSLR cameras accept them (for example, Sigma SD10). Rechargeable RCR-V3 lithium-ion batteries are also available as an alternative to non-rechargeable CR-V3 batteries.
Lithium Ion Batteries :
The second type of battery for digital cameras is proprietary battery formats. These are built to a manufacturer’s custom specifications, and can be either aftermarket replacement parts or OEM. Almost all proprietary batteries are lithium ion. While they only accept a certain number of recharges before the battery life begins degrading (typically up to 500 cycles), they provide considerable performance for their size. A result is that at the two ends of the spectrum both high end professional cameras and low end consumer models tend to use lithium ion batteries.