CN215321182U

CN215321182U - Lithium battery packaging film with composite core layer

Info

Publication number: CN215321182U
Application number: CN202022928485.4U
Authority: CN
Inventors: 雷中伟; 许翔飞; 夏旭峰
Original assignee: Zhejiang Huazheng Energy Material Co ltd
Current assignee: Zhejiang Huazheng Energy Material Co ltd
Priority date: 2020-12-09
Filing date: 2020-12-09
Publication date: 2021-12-28
Anticipated expiration: 2030-12-09

Abstract

The utility model belongs to the technical field of lithium batteries, and particularly relates to a lithium battery packaging film with a composite core layer, which comprises a protective layer, an outer adhesive layer, the composite core layer, an inner adhesive layer and a heat sealing layer which are sequentially arranged from outside to inside; the composite core layer comprises a first metal layer and an aluminum foil layer, the surfaces of the first metal layer and the aluminum foil layer are treated by a passivating agent to form the composite core layer, and then the composite core layer is compounded with a protective layer and a heat sealing layer respectively through an outer adhesive layer and an inner adhesive layer; the copper foil layer/nickel foil layer and the aluminum foil layer are rolled and compounded to form the bimetal composite foil, the copper foil layer/nickel foil layer cannot form an alloy with lithium, the ductility and the heat conductivity are improved, the punching depth performance is obviously improved, and the electrolyte corrosion resistance performance is stronger.

Description

Lithium battery packaging film with composite core layer

Technical Field

The utility model belongs to the technical field of lithium batteries, and particularly relates to a lithium battery packaging film with a composite core layer.

Background

In recent years, lithium batteries have been widely used in various small digital products and power automobile products due to their high energy density and excellent high and low temperature environmental adaptability. Mainly divided into liquid lithium batteries and polymer lithium batteries. With the wide popularization of polymer lithium battery market, the flexible package packaging material aluminum plastic film becomes one of the hot spots in the industry.

Compared with a steel shell battery and an aluminum shell battery, the aluminum-plastic film has the characteristics of light weight, capability of cold stamping and forming, high flexibility and the like, so that the polymer lithium battery has the advantages of high energy density and more various shape designs. As a core layer of the aluminum-plastic film, aluminum foil is an important component of the aluminum-plastic film due to its high moisture barrier property. The aluminum foil is O-state aluminum foil of 8021 or 8079 series. With the reduction of the thickness, the stiffness is insufficient, and the number of pinholes is increased, which brings great influence on the formability and the barrier property of the aluminum plastic film.

Among the prior art, the plastic-aluminum membrane is when dashing the hole, and the PP of inlayer can produce slight damage after being stretched to certain degree, leads to positive pole and aluminium to slightly contact to lead to the aluminium lamination to form lithium aluminium alloy, lithium aluminium alloy poor strength easily pulverizes, causes the punctiform damage of encapsulation bag, thereby makes the battery inefficacy. And the extensibility of aluminum is not as good as that of other metals such as copper, which results in the limited drawing depth performance of the aluminum-plastic film. When the battery core is prepared, the aluminum-plastic film is pierced by the internal burrs possibly during vacuumizing, and the aluminum foil is in direct contact with the electrolyte, so that the corrosion of the aluminum foil is accelerated. Therefore, it is necessary to improve it to overcome the disadvantages in practical applications.

SUMMERY OF THE UTILITY MODEL

Based on the above-mentioned shortcomings and drawbacks of the prior art, it is an object of the present invention to at least solve one or more of the above-mentioned problems of the prior art, in other words, to provide a lithium battery packaging film with a composite core layer that satisfies one or more of the above-mentioned needs.

In order to achieve the purpose of the utility model, the utility model adopts the following technical scheme:

a lithium battery packaging film with a composite core layer comprises a protective layer, an outer adhesive layer, the composite core layer, an inner adhesive layer and a heat sealing layer which are sequentially arranged from outside to inside; the composite core layer comprises a first metal layer and an aluminum foil layer, the surfaces of the first metal layer and the aluminum foil layer are processed by a passivating agent to form the composite core layer, and then the composite core layer is compounded with the protective layer and the heat sealing layer respectively through the outer adhesive layer and the inner adhesive layer.

Preferably, the first metal layer is a copper foil layer or a nickel foil layer.

Preferably, the thickness of the first metal layer is 15 μm to 30 μm.

Preferably, the thickness of the first metal layer is 20 μm.

Preferably, the thickness of the aluminum foil layer is 15 μm to 30 μm.

Preferably, the passivating agent is a trivalent chromium treating agent.

Preferably, the protective layer is polyamide and has a thickness of 15 to 30 μm.

Preferably, the outer adhesive layer is a polyurethane adhesive, and the thickness of the outer adhesive layer is 3-5 μm.

Preferably, the heat sealing layer is cast polypropylene CPP, and the thickness is 20-60 μm.

Preferably, the inner adhesive layer is a polyolefin adhesive and has a thickness of 3 to 5 μm.

Compared with the prior art, the utility model has the beneficial effects that:

according to the lithium battery packaging film with the composite core layer, the copper foil layer/nickel foil layer and the aluminum foil layer are rolled and compounded to form the bimetal composite foil, the copper foil layer/nickel foil layer cannot form an alloy with lithium, the ductility and the thermal conductivity are improved, the punching depth performance is obviously improved, and the electrolyte corrosion resistance performance is stronger.

Drawings

Fig. 1 is a schematic structural diagram of a lithium battery packaging film of a composite core layer according to a first embodiment of the present invention;

in the figure: 1 protective layer, 2 outer adhesive layers, 3 composite core layers, 3-a aluminum foil layer, 3-b first metal layer, 4 inner adhesive layers and 5 heat sealing layers.

Detailed Description

In order to more clearly illustrate the embodiments of the present invention, the following description will explain the embodiments of the present invention with reference to the accompanying drawings. It is obvious that the drawings in the following description are only some examples of the utility model, and that for a person skilled in the art, other drawings and embodiments can be derived from them without inventive effort.

Example 1:

as shown in fig. 1, the present embodiment provides a lithium battery packaging film with a composite core layer, which includes a protective layer 1, an outer adhesive layer 2, a composite core layer 3, an inner adhesive layer 4, and a heat sealing layer 2, which are sequentially arranged from outside to inside; the composite core layer 3 comprises a first metal layer 3-b and an aluminum foil layer 3-a, the surfaces of the first metal layer 3-b and the aluminum foil layer 3-a are processed by a passivating agent to form the composite core layer 3, and then the composite core layer is compounded with the protective layer 1 and the heat sealing layer 2 respectively through an outer adhesive layer 2 and an inner adhesive layer 5.

The composite core layer 3 is an improvement on a single-layer aluminum foil, the original single-layer aluminum foil is changed into aluminum and another metal for rolling and compounding, and then thermal annealing is carried out under a certain temperature condition to form a bimetal composite foil, so that the performance advantages of the two metals are combined, and a composite material with better mechanical property can be obtained.

In the embodiment, the copper foil is selected as another metal for rolling compounding, namely the first metal layer 3-b is the copper foil layer, and the copper foil does not form an alloy with lithium and has better performances in ductility and thermal conductivity, so that the aluminum/copper composite foil after rolling compounding is obviously improved in punching depth performance and has stronger electrolyte corrosion resistance.

In this embodiment, the surface of the aluminum foil layer 3-a is bonded to the protective layer 1, and the surface of the copper foil layer is bonded to the heat seal layer 5. Because the PP can not form alloy with lithium of the anode of the battery pack when the PP is damaged and is used as a protective layer 1 of the aluminum foil layer, the aluminum foil layer is prevented from being corroded by electrolyte.

The protective layer 1 is made of polyamide (nylon) material and has a thickness of 15-30 μm. The outer adhesive layer 2 is made of polyurethane adhesive and has a thickness of 3-5 μm. The aluminum foil layer 3-a is used as a binding surface with the protective layer, the copper foil layer is used as a binding surface with the heat sealing layer 5, the thickness of the aluminum foil layer 3-a is 15-30 mu m, and the thickness of the copper foil layer is 20 mu m.

The heat sealing layer is made of cast polypropylene CPP, and the thickness of the cast polypropylene CPP is 20-60 mu m. An inner adhesive layer is arranged between the heat sealing layer and the first metal layer. The inner adhesive layer 4 is a maleic anhydride modified polyolefin adhesive with the thickness of 3-5 μm.

In this embodiment, the lithium battery packaging film with the composite core layer 3 being the aluminum/copper composite foil is prepared, wherein the surfaces of the aluminum foil layer 3-a and the copper foil layer are passivated, and the passivating agent is a trivalent chromium treating agent and contains an acrylic resin component. After treatment, the surface of the aluminum foil layer 3-a and the protective layer 1 are compounded by a dry method, and the surface of the copper foil layer and the heat sealing layer 5 are compounded by a dry method.

Example 2:

the lithium battery packaging film of the composite core layer of the present embodiment is different from that of embodiment 1 in that:

the first metal layer in this embodiment is a nickel foil layer, and since the nickel foil does not form an alloy with lithium, and has better ductility and thermal conductivity, the aluminum/nickel composite foil after roll cladding is significantly improved in drawing depth performance, and has stronger electrolyte corrosion resistance.

In this embodiment, a lithium battery packaging film with an aluminum/copper composite foil as a composite core layer is prepared, wherein the surfaces of the aluminum foil layer and the copper foil layer are passivated, and then the surface of the aluminum foil layer and the surface of the protective layer are respectively dry-compounded, and the surface of the copper foil layer and the heat seal layer are dry-compounded.

In the embodiment, the thickness of the protective layer is 15-30 μm, the thickness of the outer adhesive layer is 3-5 μm, the thickness of the aluminum foil layer is 15-30 μm, the thickness of the nickel foil layer is 15-30 μm, the thickness of the inner adhesive layer is 3-5 μm, and the thickness of the heat sealing layer is 20-60 μm.

Other structures can refer to embodiment 1.

Comparative example 1:

in the comparative example, the single-layer aluminum foil in the prior art is selected as the composite core layer, and the coating and the laminating are carried out in a dry method composite mode to prepare the single-layer aluminum foil packaging film. And after the passivation treatment, the inner surface and the outer surface of the aluminum foil layer are respectively compounded with the protective layer polyamide and the heat-sealing layer CPP by a dry method.

The samples of examples 1-2 and comparative example 1 were subjected to the deep drawing and the 85 ℃ electrolyte immersion test, respectively, to obtain the deep drawing property data and the inner layer peeling force variation data under the electrolyte immersion as shown in tables 1 and 2.

TABLE 1 deep-draw formability test

TABLE 2 electrolyte immersion inside layer peel force test at 85 deg.C

As can be seen from the test results of tables 1 and 2, the lithium battery encapsulating films of the composite core layers of examples 1-2 are superior to those of comparative example 1 in both the punch-through performance and the inner electrolyte resistance.

The corrosion resistance was further tested by selecting the encapsulation films of examples 1-2 and comparative example 1, dropping electrolyte (1000ppm water content) on the inner bonding surface of the core layer, and observing pitting corrosion under experimental conditions (25 ℃, 50% RH). The degree of corrosion is divided into four grades: a (no corrosion), B (slight corrosion), C (more severe corrosion), D (severe corrosion). The data of table 3 were obtained.

TABLE 3 Corrosion resistance test

As can be seen from the test results of table 3, the lithium battery encapsulation films of the composite core layers of examples 1-2 all had better corrosion resistance than comparative example 1.

The data show that the performance of the lithium battery packaging film with the composite core layer is superior to that of a single-layer aluminum foil plastic film.

The foregoing has outlined rather broadly the preferred embodiments and principles of the present invention and it will be appreciated that those skilled in the art may devise variations of the present invention that are within the spirit and scope of the appended claims.

Claims

1. A lithium battery packaging film with a composite core layer is characterized by comprising a protective layer, an outer adhesive layer, the composite core layer, an inner adhesive layer and a heat sealing layer which are sequentially arranged from outside to inside; the composite core layer comprises a first metal layer and an aluminum foil layer, the surfaces of the first metal layer and the aluminum foil layer are processed by a passivating agent to form the composite core layer, and then the composite core layer is compounded with the protective layer and the heat sealing layer respectively through the outer adhesive layer and the inner adhesive layer.

2. The composite core layer lithium battery packaging film as claimed in claim 1, wherein the first metal layer is a copper foil layer or a nickel foil layer.

3. The lithium battery packaging film of a composite core layer as claimed in claim 1 or 2, wherein the thickness of the first metal layer is 15 μm to 30 μm.

4. The lithium battery packaging film of composite core layer as claimed in claim 3, wherein the thickness of the first metal layer is 20 μm.

5. The lithium battery packaging film with a composite core layer as claimed in claim 1 or 2, wherein the thickness of the aluminum foil layer is 15 μm to 30 μm.

6. The composite core lithium battery packaging film of claim 1, wherein the passivating agent is a trivalent chromium treatment agent.

7. The lithium battery packaging film with a composite core layer as claimed in claim 1, wherein the protective layer is polyamide and has a thickness of 15 μm to 30 μm.

8. The lithium battery packaging film with a composite core layer as claimed in claim 1, wherein the outer adhesive layer is a polyurethane adhesive and has a thickness of 3 μm to 5 μm.

9. The lithium battery packaging film with a composite core layer as claimed in claim 1, wherein the heat sealing layer is cast polypropylene CPP with a thickness of 20 μm to 60 μm.

10. The lithium battery packaging film with a composite core layer as claimed in claim 1, wherein the inner adhesive layer is a polyolefin adhesive and has a thickness of 3 μm to 5 μm.