Packaging requirements for the hottest flexible pa

2022-08-01
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Packaging requirements for flexible packaging materials and batteries

polymer batteries are finally formed by using flexible packaging materials. Strictly speaking, it can not be called packaging, because in the field of polymer lithium-ion batteries, flexible packaging materials and contents form cells together, and the cells are assembled to form batteries. Therefore, flexible packaging materials can be regarded as an integral part of batteries. However, the materials it uses are common packaging materials, and they are really mainly used to protect the contents. Therefore, people still call it packaging

because the flexible packaging material can be regarded as a component of the battery, it has an important impact on the performance of the battery. When the content of water and oxygen in the battery reaches a certain level, the capacity of the polymer lithium-ion battery will become smaller, the voltage drop will increase, the battery will not be charged or discharged, the cycle life will decline, and the battery may eventually fail

flexible packaging materials can maintain the battery performance by blocking water and oxygen. Therefore, the barrier property of flexible packaging materials has an important impact on the battery. In addition, some organic substances in the flexible packaging materials may dissolve in the electrolyte to produce electrochemical reaction and destroy the performance of the battery; If the electrolyte is swelled by the flexible packaging materials, the mixing ratio of the electrolyte will be changed, which is unfavorable to the battery performance

General requirements for flexible packaging materials of polymeric physical ion batteries

the flexible packaging materials used for polymer lithium-ion batteries are aluminum-plastic composite films, and the general requirements are as follows:

① excellent heat sealing performance

polymer lithium-ion batteries are very sensitive to high temperature, and the general operating temperature is lower than 60 ℃. It is required that the lower the heat sealing temperature, the better the flexible packaging materials with sufficient heat sealing strength. Generally speaking, the heat sealing temperature should not be higher than 15 ℃. In order to break through the previous thinking mode of manufacturing, sales and service, enterprises must adopt appropriate edge cooling measures when adopting higher heat sealing temperature, so as to prevent the conduction and radiation during heat sealing from damaging the battery

② the heat sealing material does not react with the electroplating solution

the inner layer of the flexible packaging material can neither be dissolved by the electrolyte nor swell with the electrolyte. If the flexible packaging material is dissolved by the electrolyte, since the working voltage of the battery is up to 3.6V or more, it is required that the components dissolved in the foam granulator will undergo electrochemical reaction to produce gas; If the flexible packaging material swells the electrolytic discharge, it will change the concentration of electrolyte and affect the performance of the battery

③ high water and oxygen resistance

water vapor permeability coefficient is required to reach 10-4 ~ 10-6g/m2 D 1atm

therefore,

oxygen permeability coefficient is required to reach 10-1 ~ 10-3cm3/m2 D 1atm

④ high flexibility and mechanical strength

production and assembly of polymer lithium ion batteries, Higher requirements are put forward for the flexibility of the soft experimental force: (0.098, 0.246, 0.49, 0.98, 1.96, 2.94, 4.90, 9.80) n packaging materials; The safety guarantee in the process of use puts forward high requirements for the mechanical strength and heat sealing strength of flexible packaging materials

⑤ it has good resistance to electrolyte invasion and foam

the flexible packaging material can not leak the electrolyte during long-term storage and turnover after packaging the cell

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