Jelly roll (battery)

The jelly roll or Swiss roll design is the design used in the majority of cylindrical rechargeable batteries, including nickel–cadmium (Ni-Cd), nickel-metal hydride (Ni-MH), and lithium-ion (Li-ion).

The design has this name because the cross section of the battery looks like a Swiss roll.

This sandwich is then rolled up and inserted into a hollow cylinder casing.

A label with the brand name is then applied, or a blank protective label, often green (for Ni-MH) or blue (for Ni-Cd) for a generic or OEM battery.

The Swiss roll design is likewise used for the plates of cylindrical capacitors.

The inside of a Nickel-metal hydride battery, showing the jelly roll design:
  1. positive terminal
  2. outer metal casing (also negative terminal)
  3. positive electrode
  4. negative electrode with current collector (metal grid, connected to metal casing)
  5. separator (between electrodes)