Do rechargeable lithium-ion batteries exist in standard sizes like AA, AAA, C or D?
Yes, they are finally available. However, only a few Chinese companies manufacture them. These batteries are AA and AAA rechargeable lithium polymer batteries that output 1.5 volts.
Lithium-ion batteries normally operate at 3.7V per cell. The circuitry inside the cells reduces the voltage to 1.5 volts. The batteries have a capacity of 3400mWh which matches Eneloop Pro (NiMH batteries with the highest capacity). Additionally, lithium-ion cells are lighter than NiMH cells.
Other Lithium-Ion Rechargeables
A single 18650 battery can replace two CR123A batteries, although at a lower voltage (but much higher amperage). However, the 18650 is a wider cell and will not fit into a flashlight that is designed strictly for the narrower CR123As. Most modern tactical LED lights are designed to use a single 18650 or two CR123As, but it’s best to check before buying. See our article on The Best 18650 Batteries for more information.
There are also numerous other types of lithium-ion batteries made for specific laptops and other electronics gadgets. There is currently no standard size for these lithium-ion cells.