Jelly roll (battery)
The jelly roll or Swiss roll design is the design used in the majority of cylindrical rechargeable batteries, including nickel–cadmium, nickel-metal hydride, and lithium-ion batteries. The design has this name because the cross section of the battery looks like a Swiss roll.
In this design, an insulating sheet is laid down, then a thin layer of an anode material is laid down, a separator layer is applied, and a cathode material is layered on top. This sandwich is then rolled up and inserted into a hollow cylinder casing. The battery is sealed, metal contacts are attached, and an optional button top is applied if the battery is intended to replace an AAA/AA/C/D alkaline battery. A label with the brand name is then applied, or a blank protective label, often green or blue for a generic or OEM battery.
Occasionally, the design is also used for primary batteries, like lithium iron disulfide patented by Energizer, although most common primary batteries use the conventional rod-paste-tube design, like the zinc-carbon and its successor the alkaline battery.
The Swiss roll design is likewise used for the plates of cylindrical capacitors.