Packaging requirements for the hottest flexible pa

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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't be called packaging, because in the field of polymer lithium-ion batteries, flexible packaging materials and contents together form cells, which are then assembled into batteries. Therefore, flexible packaging materials can be regarded as a part of batteries. However, the materials it uses are common packaging materials, and they are really mainly used to protect the contents. Therefore, people are still used to calling it packaging

because the flexible packaging material can be regarded as an integral part of the battery, it has an important impact on the electrical coherence standard: the performance of the cell. When the content of water and oxygen in the battery reaches a certain level, the capacity of polymer lithium-ion battery will become smaller, the voltage drop will increase, the battery will not be charged or discharged, and the cycle life will decline, which may eventually lead to the failure of the battery

flexible packaging materials can maintain the performance of batteries by blocking water and oxygen. Therefore, the barrier property of flexible packaging materials has an important impact on batteries. In addition, some organic substances in flexible packaging materials may dissolve in electrolyte to produce electrochemical reaction and damage the performance of the battery; If the electrolyte is swollen by the flexible packaging materials, the mixing proportion of the electrolyte will be changed, which is detrimental to the performance of the battery. At the end of the test, automatically calculate the maximum air force, upper and lower yield strengths, hysteresis ring method, gradual approximation method, non proportional extension strength, tensile strength, compressive strength, constant extension strength at any point, constant load extension at any point, elastic modulus, elongation, maximum value, minimum value, average value of stripping interval Tortuosity modulus, etc.

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:

at present,

① they have excellent heat sealing properties

polymer lithium-ion batteries are very sensitive to high temperature, and the general operating temperature is lower than 60 ℃. Under the condition of sufficient heat sealing strength, the lower the heat sealing temperature, the better. Generally speaking, the heat sealing temperature should not be higher than 150 ℃. When adopting higher heat sealing temperature, appropriate edge cooling measures must be taken to prevent the conduction and radiation during heat sealing from damaging the battery, according to a Dow customer

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

the inner material 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, the dissolved components will undergo electrochemical reaction and produce gas due to the working voltage of the battery being more than 3.6V; If the flexible packaging material swells the electrolytic discharge, it will change the concentration of electrolyte and affect the performance of the battery

③ it has high water and oxygen resistance

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

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

④ it has high flexibility and mechanical strength

the production and assembly of polymer lithium-ion batteries put forward higher requirements for the flexibility of flexible packaging materials; The safety guarantee in the use process puts forward high requirements for the mechanical strength and heat sealing strength of flexible packaging materials

⑤ it has good resistance to electrolyte bubble invasion

after packaging the cell, the electrolyte cannot leak during long-term storage and turnover

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