Flexible packaging film for lithium ion battery, and preparation method of flexible packaging film

Abstract

The invention discloses a flexible packaging film for a lithium ion battery. The flexible packaging film comprises a cast polypropylene film layer, a first adhesive layer, a first rigid protective layer, a high molecular insulation middle cell fixing layer, a second rigid protective layer, a second adhesive layer and a polyester resin layer, wherein the first rigid protective layer and the secondrigid protective layer are thermally pressed on the two side surfaces of the high molecular insulation middle cell fixing layer respectively; the cast polypropylene film layer is adhered to the firstrigid protective layer through the first adhesive layer; and the polyester resin layer is adhered to the second rigid protective layer through the second adhesive layer. Therefore, the overall structure of the flexible packaging film of the lithium ion battery has good ductility and hardness; the formability is better; the use of a conductive material-aluminum foil is avoided; the possibilities ofshort-circuiting the packaging film and a negative electrode sheet and forming an ion channel and an electron channel are avoided; the possibility of electrochemical corrosion of the soft package lithium ion battery is avoided; and the safety and reliability of the soft package lithium ion battery are greatly improved.

Description

technical field [0001] The invention relates to the field of packaging films for lithium-ion batteries, in particular to a flexible packaging film for lithium-ion batteries and a preparation method thereof. Background technique [0002] Soft-pack lithium-ion battery refers to a liquid lithium-ion battery covered with a polymer shell, and the lithium-ion battery is structurally packaged with aluminum-plastic film. In the event of a safety hazard, the soft-pack lithium-ion battery will only burst at most. open. [0003] At present, the outer packaging film of soft-packed lithium-ion batteries is aluminum-plastic film, which is the key material for the packaging of soft-packed lithium-ion battery cells. After the single-chip battery is assembled, it is sealed with aluminum-plastic film to form a battery. To protect the contents. [0004] The middle material of the aluminum-plastic film is aluminum, and the soft-packed lithium-ion battery packaged with the aluminum-plastic fil...

AI Technical Summary

Problems solved by technology

[0004] The middle material of the aluminum-plastic film is aluminum, and the soft-packed lithium-ion battery packaged with the aluminum-plastic film has always had the risk of electrochemical corrosion. The main reason is that the aluminum in the aluminum-plastic film is a conductor, and the aluminum-plastic The risk of short-circuiting between the aluminum layer in the film and the negative nickel tab, once the short-circuit occurs, it will provide an electronic channel for electrochemical corrosion, and the damage of polypropylene (PP) is unavoidable during the heat-sealing process of the aluminum-plastic film. That is, ion channels exist all the time, so that ion channels and electronic channels exist at the same time, and electrochemical corrosion will definitely occur

Lithium-ion batteries with electrochemical corrosion will quickly swell and eventually leak during storage and use. Lighter cases can cause lithium-ion batteries to fail, and even cause fire risks in severe cases.

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