So [Travis] decided to upgrade it to make use of the ever-so-common, 18650 lithium-ion ... A 3D printed 18650 to D-cell adapter would look quite nice… Finally, in order to make the battery ...

French researchers have announced a prototype of an 18650 sodium-ion battery ... By comparison, a typical lithium-ion battery has around 110 Wh/kg and tops out at about 1200 recharge cycles.

An 18650 potassium-ion battery represents a category of rechargeable batteries that employs potassium ions as the charge ...