Pressure-resistant composite film for lithium battery and preparation method of pressure-resistant composite film

Abstract

The invention discloses a pressure-resistant composite film for a lithium battery and a preparation method of the pressure-resistant composite film, and the pressure-resistant composite film comprises a protective layer, a first bonding layer, a first corrosion-resistant coating, a pressure-resistant layer, a second corrosion-resistant coating, a second bonding layer, a heat sealing layer and a slipping agent layer which are sequentially arranged from top to bottom, the protective layer, the first bonding layer, the first corrosion-resistant coating, the pressure-resistant layer, the second corrosion-resistant coating, the second bonding layer and the heat sealing layer are formed into an integral composite film structure through dry compounding or high-temperature hot pressing, the lower surface of the heat sealing layer is coated with the slipping agent layer, the thickness of the pressure-resistant layer is 10-150 microns, and the pressure-resistant layer is made of one of copper foil, aluminum foil and steel foil. According to the composite film for the soft package battery, the metal foil with higher hardness is adopted by the pressure-resistant layer, so that the hardness of the composite film for the soft package battery is improved, the pressure-resistant capability of the battery is further improved, and meanwhile, the slipping agent is coated on the surface of the heat sealing layer, so that the shell punching performance is improved, and the composite film has the advantages of good shell punching performance, pressure-resistant performance and the like at the same time.

Description

technical field [0001] The invention belongs to the technical field of lithium battery outer packaging materials, in particular to a pressure-resistant composite film for lithium batteries and a preparation method thereof. Background technique [0002] The current outsourcing types of lithium batteries are mainly divided into three systems: soft pack, square, and cylinder. Among them, the representative outsourcing material for soft pack lithium batteries is aluminum-plastic composite film, the outsourcing material for square lithium batteries is usually aluminum shell, and the outsourcing material for cylindrical lithium batteries is The material is usually a steel shell. Both the aluminum shell and the steel shell have the advantages of strong internal pressure resistance, and have the characteristics of being stable and not deformed when the internal gas is pressurized. In the case of short circuit, etc., the air pressure is not easy to discharge, and it is easy to cause...

AI Technical Summary

Problems solved by technology

[0004] 1. The aluminum-plastic composite film is relatively soft. After packaging into a battery, the gas generated by charging and discharging will easily deform the battery pack, and cause certain mutual extrusion deformation inside the battery module, which will affect the safety of the battery.

[0005] 2. During the shelling process of the pouch battery, if image 3 and Figure 4 As shown, there will be local excessive stretching at the stretched position, resulting in a reduction in the local residual thickness, causing the severe stretched position to collapse easily, and there will be deformation when slightly touched, making the battery weak locally, which may become a breakthrough point for battery safety hazards

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