What functional part does the protection circuit serve in a battery?

The protection circuit in a battery is crucial for controlling the charge and discharge process. It ensures that the battery operates within safe limits by monitoring parameters such as voltage, current, and temperature. This functionality helps prevent overcharging, which can lead to battery damage or failure, and it also helps avoid excessive discharging, which can result in reduced capacity or irreversible harm to the battery cells.

While other functions mentioned, like conducting electrical charges, regulating temperature, and filtering impurities, are important in overall battery functionality and management, they do not encapsulate the primary role of the protection circuit. The central aim of a protection circuit is to safeguard the battery during its operation by managing how it charges and discharges, thereby enhancing safety and prolonging the life of the battery.