What are the requirements for flexible packaging materials for lithium-ion polymer batteries?

1. The permeability of water vapor with extremely high barrier properties should be less than 1×10-4~1×106g/m2d1atm; the permeability of oxygen should be less than 1×10-1~1×10-3g/m2d1atm; this The barrier properties are required to be about 10,000 times higher than that of general aluminum-plastic composite materials. It can be seen that the thickness of aluminum foil of general flexible packaging materials must be greater than 30um to guard against the slow penetration of water vapor. Therefore, it is difficult for general composite materials to meet the requirements. Generally, thicker aluminum foil is used, and a composite structure of 3 to 7 layers is required, and various composite methods are comprehensively applied. The structure of flexible packaging materials generally has the following 3 types: a: ONLY/AL/CPP; b: PET/ONLY/AL/CPP; c: PET/AL/PET/EMAA, b. Two structures are more suitable for forming packaging. c structure is only suitable for general packaging. 2. Lithium ion polymer battery with good heat sealing performance is sensitive to high temperature. Generally, the use temperature is lower than 60℃. This requires flexible packaging materials to meet the requirements of heat sealing strength. The lower the heat sealing temperature, the better. Generally, In other words, the heat sealing strength should not be less than 35N/15mm, and the heat sealing temperature should not be higher than 150℃. If a higher temperature is used, cooling measures must be adopted. The heat-sealing time should generally not exceed 3s to beware of damage to the battery core by heat radiation and heat conduction. 3. The inner layer material does not react with the electrolyte. The inner layer material of the flexible packaging material can neither be dissolved by the electrolyte nor swelled by the electrolyte. If the inner layer material is dissolved by the electrolyte, the dissolved components will undergo a chemical reaction and gas will appear; if the inner layer material is swelled by the electrolyte, the concentration or component ratio of the electrolyte will be changed and the performance of the cell will be affected. The electrolyte used in the polymer is an organic electrolyte composed of a variety of lipids, in which the electrolyte lithium salt will be analyzed into a highly acidic hydrofluoric acid in the presence of moisture. This requires that the bonding layer between the inner layer material and the aluminum foil is not affected by the electrolyte and the hydrofluoric acid present in the electrolyte, so as to prevent the inner layer material and the aluminum foil from peeling off and affecting the barrier properties of the packaging material. Many Japanese manufacturers now use a special adhesive that is resistant to electrolyte and hydrofluoric acid for the inner layer material and aluminum foil of the flexible packaging material processed by Japanese manufacturers to prevent the material from being peeled off after being soaked in the electrolyte. The aluminum foil The peel strength from the inner layer material directly affects the sealing performance of the battery. 4. It has good ductility, flexibility and mechanical strength. The processing process of lithium-ion polymer batteries puts forward higher requirements on the flexibility of packaging materials. Nowadays, the more widely used cold press molding packaging methods are used for packaging materials. The ductility also puts forward higher requirements. The safety guarantee during use also puts forward higher requirements on the mechanical strength of flexible packaging materials. Disclaimer: Some pictures and content of articles published on this site are from the Internet. If there is any infringement, please contact to delete.