The lithium battery of the mobile phone is mainly composed of a plastic case upper and lower cover, a lithium battery core, a protection circuit board and a recoverable fuse.

The functions of each part are as follows:

(1) Lithium battery: Provides rechargeable power.

(2) Protection circuit board (PCB): to prevent the battery from overcharging, overdischarging and short circuit.

(3) Recoverable fuse (PTC): Positive thermistor plays a role of high temperature protection, and it is also a double protection after protection circuit board failure.

(4) Recoverable fuse (NTC): negative thermistor, which senses the internal temperature of the battery to protect it from low temperatures.

(5) Identification resistance: identify original batteries, non-original batteries cannot be used.