The outer shell of a square aluminum shell battery cell is usually covered with a blue thin film (commonly referred to as the "blue film")

The blue film mainly has the following functions:

1. Insulation protection

Insulation between battery cells: to prevent short circuits caused by contact between aluminum shells (conductors) and adjacent battery cells or structural components during module stacking; (Directly affecting module security)

Shell edge passivation: Aluminum shell stamping/welding edges may have burrs, and blue film coverage can avoid puncturing adjacent insulation layers; 

Voltage endurance level: usually able to withstand voltages above 1000V, matching the requirements of high-voltage battery systems; 

2. Thermal management assistance

Thermal conductive medium layer: Some blue films contain ceramic coatings, which can improve the thermal conductivity efficiency between the battery cell and the cooling plate; 

High temperature tolerance: able to withstand temperatures above 150 ℃, delaying the spread of fire in the early stages of thermal runaway; 

3. Environmental protection

Anti electrolyte corrosion: block electrolyte leakage from corroding the shell (reduce the risk of after-sales failure)

  Anti oxidation: Protect the surface of the aluminum shell from oxidation in humid environments (affecting reliability) 

4. Mechanical protection

Scratch resistant: Protect the anodized layer on the surface of the shell during assembly and transportation (to avoid insulation failure caused by this)

  Buffer energy absorption: The thickness of the blue film is usually greater than 0.1mm, which can absorb some mechanical vibration energy;

Motor, also known as starter motor. It drives the starter rotor to rotate by applying force to the coil in the magnetic field, and the small gear on the rotor drives the engine flywheel to rotate, thereby driving the crankshaft to rotate and start the car. The innovation of new low-cost spark plugs and starters with ceramic core bases has laid the technological foundation for the development of automobiles.