Jelly roll (battery)
The jelly roll or Swiss roll design is the design used in the majority of cylindrical rechargeable batteries. 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 (NiMh) or blue (NiCd), for a generic or OEM battery.
The design gets its name because the cross section of the battery looks like a Swiss roll cake. Occasionally the design is also used for primary (non-rechargeable) batteries, although most primary batteries use the conventional rod-paste-tube design.