An 18650 battery[1] or 1865 cell[2] is a cylindrical lithium-ion battery common in electronic devices. The batteries measure 18 mm (0.71 in) in diameter by 65 mm (2.56 in) in length, giving them the name 18650.[3] The battery comes in many nominal voltages depending on the specific chemistry used.
Panasonic first developed the 18650 battery in 1994 "when there was a growing need for ever smaller and lighter storage batteries that could be used for ever longer periods of time".[4] They are now commonly used in power tools, electric bicycles, laptops, and electric vehicles.[5]
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.[7]
Packs
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.
Products using 18650 cells
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.[8] 18650/1865 cells are used in many laptop computer batteries, cordless power tools, many electric cars, electric scooters,[9] most e-bikes, older portable powerbanks, electronic cigarettes,[10][11] portable fans, and LED flashlights. Nominal voltage is 3.6-3.7 V.[12][5]