18650 battery

An 18650 battery or 1865 cell is a cylindrical battery size (often lithium-ion battery or sodium ion battery) common in electronic devices. The batteries measure 18 mm (0.71 in) in diameter by 65.0 mm (2.56 in) in length, giving them the name 18650. The battery comes in many nominal voltages depending on the specific chemistry used.

Sony developed the 18650 in 1991, though Panasonic claims to have done so in 1994. They are now commonly used in power tools, electric bicycles, laptops, and electric vehicles.

18650 batteries are most commonly lithium-based.

NMC811 can be doped with ZrO₂ to produce a cathode for these batteries

By 2023, some sodium-ion variants were available in the 18mm x 65 mm cylindrical cell form factor as well.

In 2024, a potassium-ion variant was unveiled in the 18650 format that utilizes a proprietary 4V Potassium Prussian White cathode and a commercially available graphite anode.

18650 batteries are commonly used in packs, where a battery management system (BMS) is required, especially once cells age and perform differently. BMS boards balance the voltage of cells in series and protect against over- and under-discharge.

18650 battery cells are used in a wide variety of products from the 1990s through the 2020s, and are widely regarded as the most produced lithium-ion cell size. 18650/1865 cells are used in many laptop computer batteries, cordless power tools, many electric cars, electric scooters, most e-bikes, older portable powerbanks, electronic cigarettes, portable fans, and LED flashlights. Nominal voltage is 3.6-3.7 V.

In the electric automobile sector, they are used in the first three vehicles manufactured by Tesla: the first-generation Roadster (late 2000s), Model S (2012+), and the Model X (2015+).

• List of battery sizes