As the main part of the cell’s internal isolation from the external environment, the aluminum film used in the packaging of lithium batteries not only has a certain mechanical strength to the external environment, but also has excellent chemical corrosion resistance to the internal chemicals. The technical requirements of aluminum-plastic film for lithium battery packaging mainly include the following aspects:

Aluminum plastic film

1. Has good puncture resistance

As the battery core packaging process generally requires 3 times of vacuuming and 3 times of heat sealing. Due to the presence of burrs on the edges of the copper mesh and aluminum mesh, the flexible packaging film will shrink inwardly when vacuuming. Once the burr pierces the inner film and reaches the aluminum foil, the electrolyte and hydrofluoric acid will directly contact the aluminum foil, which will corrode the aluminum foil and even corrode and swell the aluminum foil. Or leakage causes the battery to be scrapped.

2. The heat-sealing layer has the performance of anti-pollution, high strength, and tight heat sealing. During the second and third heat-pressing sealing of the battery cell, there is electrolyte on the inner membrane, which requires the inner membrane to be resistant. Pollution performance of high-strength heat sealing. In addition, at this time, a high peel strength must be maintained between the inner film layers to ensure the tightness and firmness after the third heat sealing.

3. The inner membrane has the performance of high temperature resistance and heat sealing without short circuit

When the power supply passes 5e10u0m thick, 2~6mn metal foil (aluminum and copper or aluminum and nickel) as the positive and negative electrode lead piles for hot press sealing, the metal electrode is protruding than other places, and the pressure is greater. If the inner membrane is within the heat sealing layer There is no high temperature softening material resistant to 17 or more, and the metal electrode is easily pressed onto the aluminum layer in the middle of the composite film to cause a short circuit.

4. Good cold stamping formability In order to make the surface of the battery cell smooth and clean, the square edge sealing is flat and the sealing is tight and firm. Reducing the outer size of the battery cell is conducive to mechanized production to improve labor efficiency and yield. Generally, the flexible packaging film is required to have good cold stamping molding. characteristic.