About cylindrical cell :
The cylindrical cell continues to be one of the most widely used packaging styles for primary and secondary batteries.
The advantages are ease of manufacture and good mechanical stability.
The tubular cylinder can withstand high internal pressures without deforming.
Many lithium and nickel-based cylindrical cells include a positive thermal coefficient (PTC) switch.
Cross section of a cylindrical cell
When exposed to excessive current, the normally conductive polymer heats up and becomes resistive, stopping current flow and acting as short circuit protection.
Once the short is removed, the PTC cools down and returns to the conductive state.
Most cylindrical cells also feature a pressure relief mechanism, and the simplest design utilizes a membrane seal that ruptures under high pressure.
Leakage and dry-out may occur after the membrane breaks. Re-sealable vents with a spring-loaded valve are the preferred design.
Some consumer Li-ion cells include the Charge Interrupt Device (CID) that physically and irreversibly disconnect the cell when activated to an unsafe pressure builds up.