CN118977480A

CN118977480A - Metal composite film and electrochemical device

Info

Publication number: CN118977480A
Application number: CN202411054915.0A
Authority: CN
Inventors: 王卉; 王小明; 曹瑞典
Original assignee: Shanghai Energy New Materials Technology Co Ltd
Current assignee: Shanghai Energy New Materials Technology Co Ltd
Filing date: 2024-08-02
Publication date: 2024-11-19

Abstract

A metal composite membrane and an electrochemical device belong to the technical field of metal plastic membranes. The metal composite film comprises a heat welding resin layer, a first adhesive layer, a first anti-corrosion layer, an intermediate metal layer and an outer base material resin layer which are sequentially overlapped; the first adhesive layer includes an acid-modified group and/or an isocyanate group, the first corrosion-preventing layer includes a nitrogen-containing polymer having an amine group reactive with the acid-modified group and/or the isocyanate group, and the content of nitrogen atoms in the first corrosion-preventing layer is greater than 0 and equal to or less than 20at%. The metal composite film can be matched with different types of first adhesive layers, the initial peel strength between the intermediate metal layer and the hot-melt resin layer of the obtained metal composite film is good, the metal composite film has good long-term effectiveness, and promotion and use of the metal composite film in the field of lithium ion batteries are facilitated.

Description

Metal composite film and electrochemical device

Technical Field

The application relates to the technical field of metal plastic films, in particular to a metal composite film and an electrochemical device.

Background

At present, lithium ion batteries are mainly divided into three major categories of square, cylindrical and soft package, wherein the shells of the square and cylindrical are mainly made of hard shells such as aluminum alloy, stainless steel and the like, the aluminum alloy shell can be made of aluminum materials, and the soft package shell formed by laminating metal and resin adopts a metal composite film, so that the problem of inflexible appearance design of the hard-packaged battery is greatly solved.

The metal composite film comprises an outer base material resin layer, an intermediate metal layer, a first adhesive layer and a heat welding resin layer from outside to inside in sequence. As an outer coating material of a battery, the metal composite film is required to have electrolyte corrosion resistance, so that the problems of leakage and the like of a battery shell can be prevented, and the service life of the battery is ensured.

In general, when the corrosion prevention effect is not satisfactory, if moisture is mixed in the battery manufacturing process, the metal in the metal composite film for lithium ion battery exterior packaging is reacted with lithium salt in the electrolyte solution to generate corrosive Hydrogen Fluoride (HF), and the hydrogen fluoride passes through the heat-fusible resin layer and the first adhesive layer to reach the surface of the intermediate metal layer, thereby corroding the metal and causing detachment between the intermediate metal layer and the heat-fusible resin layer. The possibility of occurrence of leakage of the electrolyte from the battery is increased. The corrosion-preventing treatment of the intermediate metal layer greatly affects the metal composite film.

Currently, the main components of the anti-corrosion treatment liquid for metal composite films are trivalent chromium compounds, fluorides, amino phenol resins and phosphoric acid. After the intermediate metal layer is subjected to corrosion prevention treatment of the corrosion prevention liquid, the corrosion resistance degree of the metal composite film can be improved in some common electrolyte environments. It is currently common practice to select different types of preservative treatments depending on the type of first adhesive layer. When the same preservative is matched with different types of first adhesive layers, the treatment effect difference is huge. When the treatment effect is poor, moisture possibly permeates the battery outer package, so that Hydrogen Fluoride (HF) is generated by the electrolyte, the corrosion prevention treatment effect of the corrosion prevention liquid is not ideal, interlayer separation of the metal composite film for the lithium ion battery is easily caused, and popularization and use of the metal composite film in the field of lithium ion batteries are affected.

And assuming that the corrosion protection layer comprises a nitrogen-containing polymer and the adhesive layer comprises an acid-modifying group and/or an isocyanate group as shown in the present application, there is also a possibility that cracks are easily generated between the corrosion protection layer and the inner adhesive layer after the reaction under the influence of external force. When the flexibly packaged lithium battery is used for a long time, the intruded moisture reacts with the electrolyte to generate hydrogen fluoride. Hydrogen fluoride is easy to invade from cracks, so that the peeling strength of the anti-corrosion layer and the inner adhesive layer is reduced, and finally layering is achieved.

Disclosure of Invention

The application aims to overcome the defects of the prior art and provides a metal composite membrane and an electrochemical device.

Embodiments of the present application are implemented as follows:

in a first aspect, an example of the present application provides a metal composite film including a heat fusion resin layer, a first adhesive layer, a first corrosion prevention layer, an intermediate metal layer, and an outer base material resin layer, which are sequentially stacked;

Wherein the first adhesive layer comprises acid-modified groups and/or isocyanate groups, the first anti-corrosion layer comprises a nitrogen-containing polymer, the nitrogen-containing polymer has amine groups which react with the acid-modified groups and/or the isocyanate groups, and the content of nitrogen atoms in the first anti-corrosion layer is more than 0 and less than or equal to 20at%.

According to the metal composite film provided by the application, the nitrogen-containing polymer with certain nitrogen atom content is added into the first anti-corrosion layer, so that the metal composite film can be matched with different types of first adhesive layers, the preparation cost of the metal composite film is reduced, the preparation efficiency is improved, the hardness between the intermediate metal layer and the hot-melt resin layer of the obtained metal composite film is reasonable, cracks are not easily generated due to the influence of external force, the initial peel strength between the intermediate metal layer and the hot-melt resin layer is good, the long-term effectiveness is good, and the promotion and the use of the metal composite film in the field of lithium ion batteries are facilitated.

In a second aspect, the present example provides an electrochemical device using the metal composite film provided in the first aspect of the present application.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic view of a metal composite film according to some embodiments of the present application;

FIG. 2 is a schematic illustration of a metal composite film according to some embodiments of the present application;

FIG. 3 is a schematic view of a metal composite film according to some embodiments of the present application;

FIG. 4 is a schematic view of a metal composite film according to some embodiments of the present application;

fig. 5 is a schematic structural diagram of a metal composite film according to some embodiments of the present application.

Icon: 1000-metal composite film; 10-heat welding the resin layer; 11-a first adhesive layer; 12-a first corrosion protection layer; 13-an intermediate metal layer; 14-a second corrosion protection layer; 15-a second adhesive layer; 16-an outer substrate resin layer; 17-a coloured layer.

Detailed Description

Embodiments of the present application will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present application and should not be construed as limiting the scope of the present application. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.

The metal composite film and the electrochemical device according to the embodiments of the present application are specifically described below:

Referring to fig. 1 to 5, the present application provides a metal composite film 1000, which includes a heat-welding resin layer 10, a first adhesive layer 11, a first corrosion-preventing layer 12, an intermediate metal layer 13, and an outer base resin layer 16, which are stacked in this order.

Wherein the first adhesive layer 11 includes an acid-modified group and/or an isocyanate group, the first corrosion prevention layer 12 includes a nitrogen-containing polymer having an amine group reactive with the acid-modified group and/or the isocyanate group, and the content of nitrogen atoms in the first corrosion prevention layer 12 is greater than 0 and equal to or less than 20at%.

The first anticorrosive layer 12 is provided between the intermediate metal layer 13 and the first adhesive layer 11, which is advantageous in preventing hydrogen fluoride from reaching the surface of the intermediate metal layer 13 and preventing detachment between the intermediate metal layer 13 and the thermally fused resin layer 10 when corrosive Hydrogen Fluoride (HF) is generated in the battery.

Wherein the acid modifying group reactive with the amine group includes, but is not limited to, at least one of a carboxyl group, a sulfonic group, a maleic group, a sulfinic group, a sulfenate group, a phosphoric group, a phosphonic group, and the like.

The content of nitrogen atoms in the first anticorrosive layer 12 means that the content of elements deep in the first anticorrosive layer 12 is detected by a method (XPS-ESCA method) described later, and the elements added to the first anticorrosive layer 12 by default are uniformly dispersed in the first anticorrosive layer 12.

When the nitrogen atom content in the first anticorrosive layer 12 is too high (more than 20 At%), the degree of bonding of the amino group (NH ₂) to the first adhesive layer 11 increases, resulting in an increase in hardness between the first anticorrosive layer 12 and the first adhesive layer 11 after the reaction, and cracks are easily generated after being affected by external force. When the flexibly packaged lithium battery is used for a long time, the intruded moisture reacts with the electrolyte to generate hydrogen fluoride. Hydrogen fluoride is liable to intrude from the crack, resulting in a decrease in peel strength of the first anticorrosive layer 12 and the first adhesive layer 11, and finally delamination. Therefore, controlling the content of nitrogen atoms in the first anticorrosive layer 12 within the above-described range is advantageous in improving the peel strength between the first anticorrosive layer 12 and the first adhesive layer 11.

Illustratively, the content of nitrogen atoms in the first corrosion prevention layer 12 is any one value or between any two values of 0.1At%, 1At%, 3At%, 5At%, 8At%, 10At%, 13At%, 15At%, 18At%, 20 At%.

In summary, the amine group of the nitrogen-containing polymer used in the first anti-corrosion layer 12 can react with the acid-modified group and/or the isocyanate group in the first adhesive layer 11, and the content of nitrogen atoms in the first anti-corrosion layer is controlled, so that the first anti-corrosion layer 12 and the first adhesive layer 11 can be combined through covalent bonds, the adhesion between the first anti-corrosion layer 12 and the first adhesive layer 11 is effectively improved, the connection between the intermediate metal layer 13 and the heat-welding resin layer 10 is further firm, the initial peeling strength between the intermediate metal layer 13 and the heat-welding resin layer 10 of the metal composite film 1000 and the corrosion resistance in the environment of anhydrous and water electrolyte are improved, the long-acting stability of the metal composite film 1000 as an external packing material for a lithium ion battery device can be realized, the first anti-corrosion layer 12 can be matched with different types of first adhesive layers, and the production efficiency of the metal composite film 1000 is improved, and the production cost is reduced.

In some alternative embodiments, referring to fig. 2-5, the metal composite film 1000 further includes a second adhesive layer 15, the second adhesive layer 15 being located between the outer substrate resin layer 16 and the intermediate metal layer 13.

The introduction of the second adhesive layer is beneficial to improving the adhesiveness between the outer substrate resin layer 16 and the intermediate metal layer 13, so that the initial peel strength between the intermediate metal layer 13 and the outer substrate resin layer 16 is improved, and the long-acting stability of the metal composite film 1000 as an outer packaging material for a lithium ion battery device is improved.

In some alternative embodiments, referring to fig. 3-5, the metal composite film 1000 further includes a second corrosion protection layer 14, the second corrosion protection layer 14 being located between the second adhesive layer 15 and the intermediate metal layer 13.

The provision of the second anticorrosive layer 14 is advantageous in further improving the corrosion resistance of the metal composite film 1000 as an exterior material for lithium ion battery devices.

In some alternative embodiments, referring to fig. 3, the metal composite film 1000 is composed of a heat fusion resin layer 10, a first adhesive layer 11, a first corrosion prevention layer 12, an intermediate metal layer 13, a second corrosion prevention layer 14, a second adhesive layer 15, and an outer base material resin layer 16, which are sequentially stacked.

Referring to fig. 4 and 5, in some alternative embodiments, the metal composite film 1000 further includes a coloring layer 17, wherein the coloring layer 17 is disposed between the outer substrate resin layer 16 and the second adhesive layer 15 as shown in fig. 4, or wherein the coloring layer 17 is disposed on a side of the outer substrate resin layer 16 facing away from the intermediate metal layer 13 as shown in fig. 5.

By arranging the coloring layer 17, the metal composite film 1000 can meet different use requirements.

In some alternative embodiments, the second adhesive layer 15 contains a colorant. That is, the coloring layer 17 and the second adhesive layer 15 are directly compounded by directly adding the coloring agent into the second adhesive layer 15, so that the preparation cost is effectively reduced.

The following is a specific description of the layers:

[ thermal fusion resin layer 10 ]

When the metal composite film 1000 is used as an exterior material for lithium ion batteries, the heat-fusible resin layer 10 corresponds to the innermost layer, and is a layer (heat-seal layer) that functions as a seal for battery elements by heat-fusing the heat-fusible resin layers to each other when the battery is assembled.

The resin constituting the heat-fusible resin layer 10 is mainly heat-fusible, and is not particularly limited, but a resin containing a polyolefin main chain such as polyolefin or acid-modified polyolefin is preferable.

Specific examples of the polyolefin include polyethylene ethylene- α -olefin copolymers such as low-density polyethylene, medium-density polyethylene, high-density polyethylene and linear low-density polyethylene; polypropylene such as homopolypropylene, polypropylene block copolymers (e.g., block copolymers of propylene and ethylene), and random copolymers of polypropylene (e.g., random copolymers of propylene and ethylene); propylene-alpha-olefin copolymers; ethylene-butene-propylene terpolymers, and the like. Among them, polypropylene is preferable. The polyolefin resin in the case of the copolymer may be a block copolymer or a random copolymer. These polyolefin resins may be used singly or in combination of 1 kind or 2 or more kinds.

Acid-modified polyolefins are polymers modified by block polymerization or graft polymerization of a polyolefin with an acid component. As the acid-modified polyolefin, a copolymer obtained by copolymerizing the above-mentioned polyolefin with a polar molecule such as polyacrylic acid or methacrylic acid, or the like, may be used. As the acid component used for acid modification, carboxylic acid or sulfonic acid such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, and the like, and acid anhydride thereof can be used, and acrylic acid or maleic acid and acid anhydride thereof are preferably used.

The heat-fusible resin layer 10 may be composed of 1 resin alone or 2 or more resins in combination. The heat-fusible resin layer 10 may be composed of only 1 layer, or may be composed of 2 or more layers of the same or different resins.

The heat-fusible resin layer 10 may contain a slipping agent or the like as needed. When the heat-fusible resin layer 10 contains a slipping agent, the moldability of the lithium ion battery outer package can be improved. The type of the slipping agent is not particularly limited, and may be selected from known ranges. The slipping agent may be used alone or in combination of at least 2 kinds.

The slipping agent is not particularly limited, and an amide-based slipping agent is preferably used. The slipping agent may be used alone or in combination of at least 2 kinds. As the amide-based slipping agent, the surface of the outer base resin layer 16 is preferably used.

The content of the slipping agent is not particularly limited in the case where the slipping agent is present on the surface of the heat-fusible resin layer 10, but is preferably 10 to 50mg/m2, more preferably 15 to 40mg/m2, from the viewpoint of improving the moldability of the material for electronic packaging.

The slipping agent present on the surface of the heat-sealing resin layer 10 may be a slipping agent that bleeds out from the resin constituting the heat-sealing resin layer 10, or may be a slipping agent that is applied to the surface of the heat-sealing resin layer 10.

The thickness of the heat-fusible resin layer 10 is not particularly limited as long as it satisfies the function of sealing the battery element after the heat-fusible resin layers are heat-fused with each other, and is preferably about 100 μm or less, more preferably about 25 to 80 μm.

The heat-fusible resin layer 10 may contain an antioxidant or other component as necessary. The heat-fusible resin layer 10 containing the antioxidant can suppress thermal degradation in the manufacturing process. The kind of the antioxidant is not particularly limited, and may be selected from known ones. The antioxidant may be used alone or in combination of at least 2 kinds.

The heat welding resin is a single layer or a composite layer formed by a mixture of more than 1 or 2 of acid modified polyolefin resin, homopolymerized polypropylene resin, block copolymerized polypropylene resin, random copolymerized polypropylene resin and polyethylene resin.

The resin used for the heat-fusible resin layer 10 is a single layer or a composite layer composed of a mixture of 1 or more kinds of materials having a melting point of 120 to 162 ℃, more preferably 130 to 162 ℃, MFR (230 ℃) of 2 to 15g/10min, still more preferably 3 to 12g/10min, and a thickness of 20 to 120 μm, still more preferably 25 to 80 μm. In the case where the inner fusion resin layer is a composite layer, the thickness of the resin on the opposite side to be in contact with the intermediate metal layer 13 is 2 μm or more, and the melting point is 130 to 152 ℃. When the melting point is 120 ℃ or lower, fluidity is high at heating, and when heat-sealing is performed under pressure, the thickness becomes thin, and adhesion to the intermediate metal layer 13 is lowered. In addition, the pressing causes the resin in the pressed portion of the battery to flow to the non-pressed edge portion, and the crack is caused by the expansion and contraction of the battery, the external force of bending processing, etc., and the electrolyte penetrates to the intermediate metal layer 13 through the crack, so that the insulation resistance of the heat fusion resin layer 10 is reduced, the leakage phenomenon occurs, and the battery life is shortened. When the melting point exceeds 162 ℃, the crystallinity of the resin improves, so that the fluidity at the time of heat sealing under pressure becomes relatively low, and the heat resistance improves, but when the highly crystalline resin is heat sealed, a hard and brittle resin layer is formed. Therefore, when the battery expands and contracts or an external force such as bending is applied, the resin layer is liable to crack, and stable sealability for a long period of time is not obtained. When the MFR (230 ℃) of the resin is less than 2g/10min, the fluidity of the resin at the time of pressure heat sealing is low, and it is difficult to obtain stable sealability. When the MFR (230 ℃) of the resin exceeds 15g/10min, the fluidity of the resin is too high at the time of heat sealing under pressure, the thickness of the resin becomes extremely thin, and the sealing property is hardly stabilized. In addition, the pressing causes the resin in the pressed portion of the battery to flow to the non-pressed edge portion, and the crack is caused by the expansion and contraction of the battery, the external force of bending processing, etc., and the electrolyte penetrates to the intermediate metal layer 13 through the crack, so that the insulation resistance of the heat fusion resin layer 10 is reduced, the leakage phenomenon occurs, and the battery life is shortened. When the thickness of the heat-sealed resin layer 10 is less than 20 μm, it is difficult to obtain a uniform heat-sealed portion and stable sealability cannot be obtained because the thickness cannot sufficiently cover variations in the mechanical dimensions and conditions of the heat sealing device or the like. In addition, the pressing causes the resin in the pressed portion of the battery to flow to the non-pressed edge portion, the thickness of the heat-sealing resin layer 10 becomes thin, and cracks are easily caused by external forces such as expansion and contraction of the battery and bending processing, and the electrolyte permeates to the intermediate metal layer 13 through the cracks, so that the insulation resistance of the heat-sealing resin layer 10 is reduced, the leakage phenomenon occurs, and the battery life is shortened. When the thickness of the heat-fusible resin layer 10 exceeds 120 μm, the water vapor permeability increases, the water content in the battery increases, gas is generated by reaction with the electrolyte, the risk of swelling, cracking, and leakage is likely to occur, the life of the battery decreases, and the excessive hydrogen fluoride corrodes the corrosion-resistant metal layer, resulting in a decrease in the adhesion strength between the intermediate metal layer 13 and the heat-fusible resin layer 10, and the problem of electrolyte leakage is likely to occur.

[ First adhesive layer 11 ]

The first adhesive layer 11 is an intermediate layer provided to firmly adhere the thermally fused resin layer 10 to the intermediate metal layer 13.

The first adhesive layer 11 is formed of a resin capable of bonding the intermediate metal layer 13 and the heat fusion resin layer 10, and the first adhesive layer 11 includes an acid modifying group including, but not limited to, at least one of a carboxyl group, a sulfonic acid group, a maleic acid group, a sulfinic acid group, a sulfenate group, a phosphoric acid group, a phosphonic acid group, and the like, and/or an isocyanate group.

That is, the first adhesive layer 11 may use an acid-modified polyolefin-based resin such as a carboxylic acid-modified polyolefin, a carboxylic acid-modified cyclic polyolefin, a methacrylic acid-modified polyolefin, an acrylic acid-modified polyolefin, or a crotonic acid-modified polyolefin. From the viewpoint of improving the adhesion between the intermediate metal layer 13 and the inner heat fusion resin layer 10, the modified polyolefin is preferably a modified polyolefin resin such as acrylic acid, methacrylic acid, maleic acid, or anhydrous maleic anhydride. The resin constituting the first adhesive layer 11 may or may not contain a polyolefin backbone, preferably a polyolefin backbone. Whether the resin constituting the first adhesive layer 11 contains a polyolefin main chain may be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like, and the analysis method is not particularly limited. The polyolefin and its modified resin used in the first adhesive layer 11 may be the same as the resin used in the heat fusion resin layer 10, which is a polypropylene resin or a propylene and ethylene copolymer.

The first adhesive layer 11 may be a resin composition containing an acid-modified polyolefin and a curing agent, in view of stabilizing the packaging material for lithium ion batteries for long-term use. As the acid-modified polyolefin, maleic anhydride-or acrylic acid-modified polyolefin is particularly preferred.

The curing agent is not particularly limited, and may be any curing agent that cures the acid-modified polyolefin. Epoxy-based curing agents, polyfunctional isocyanate-based curing agents, carbodiimide-based curing agents, oxazoline-based curing agents, and the like can be used.

The epoxy curing agent is not particularly limited as long as it is a compound having at least 1 epoxy group. For example, epoxy resins such as bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolac glycidyl ether, glycerol polyglycidyl ether, and polyglycidyl ether are used. The polyfunctional isocyanate-based curing agent is not particularly limited as long as it is a compound having two or more isocyanate groups in the molecule. For example, polymeric or additive components of isophorone diisocyanate (PDI), hexamethylene Diisocyanate (HDI), toluene Diisocyanate (TDI), diphenylmethane diisocyanate (MDI) or mixtures of these and other polymeric reactants are used. The carbodiimide-based curing agent is not particularly limited as long as it is a compound having at least one carbodiimide group (-n=c=n-) in the molecule. Preference is given to polycarbodiimide compounds having at least two or more carbodiimide groups. The oxazoline-based curing agent is not particularly limited as long as it is a compound having an oxazoline skeleton.

The curing agent may be composed of two or more compounds from the viewpoint of improving the adhesion between the first adhesive layer 11 and the heat-fusible resin layer 10, for example.

The thickness of the first adhesive layer 11 is not particularly limited as long as it has a function as an adhesive layer, and is preferably about 1 to 80 μm, and more preferably about 1 to 50 μm.

That is, when the intermediate metal layer 13 and the heat-fusible resin layer 10 are combined with each other, the first adhesive layer 11 may be formed by using a solution type adhesive, or the first adhesive layer 11 may be formed by using a heat-fusible type adhesive.

In some alternative embodiments, the first adhesive layer 11 is made of a solvent type adhesive, and the first adhesive layer contains isocyanate groups and/or acid modifying groups.

The solution type first adhesive layer 11 is mainly composed of an acid-modified polyolefin resin as a main component and one or more of isocyanate, epoxy resin, oxazoline and the like as a curing agent or an amine compound such as triethylamine, N-dimethylethanolamine and the like, and is prepared by dissolving at least one or more of water, ethanol, isopropanol, ethyl acetate, methyl ethyl ketone, toluene, methylcyclohexane and the like in a solvent, uniformly applying the dissolved solvent to the surface of the metal subjected to corrosion prevention treatment, and heating the dissolved solvent to evaporate the solvent, thereby achieving a desired effect, for example, a thickness of the first adhesive layer 11 of about 1 to 18 μm, preferably about 1 to 15 μm.

The melting point of the acid-modified polyolefin resin in the solution type first adhesive layer 11 is 60 to 155 ℃, the weight average molecular weight is in the range of 10000 to 150000, and the acid value of the solvent type adhesive is in the range of 0.5 to 200 mgKOH/g. When an amine compound is used as a curing agent, the solution type first adhesive layer 11 is mainly composed of an acid-modified polyolefin resin and an amine compound, and the ratio of the acid-modified polyolefin to the amine compound is 10:1 to 125:1, preferably 15:1 to 50:1. the acid used for modifying polyolefin is maleic acid, fumaric acid, methacrylic acid, etc., and the amine compound is at least one of triethylamine or N, N-2 methyl ethanolamine. The acid modified polyolefin resin is a single layer or a plurality of layers composed of one or a plurality of blends of block copolymerized polypropylene resin (B-PP), random copolymerized polypropylene resin (R-PP) and homo-polymerized polypropylene resin (H-PP) with the melting point of more than 110 ℃ and the polypropylene content of more than 50 percent.

If the melting point is 60 ℃ or lower, the heat resistance is low, and the intermediate metal layer 13 and the heat-fusible resin layer 10 may be peeled off at a high temperature. If the temperature exceeds 155 ℃, the heat resistance is good, but a hard resin layer is formed during the reaction with the curing agent, and the flexibility of the metal composite film 1000 is reduced, or cracks are generated by bending, and the intermediate metal layer 13 and the heat-seal resin layer 10 may be peeled off. If the weight average molecular weight is 10000 or less, the fluidity of the resin is high when heated, and the thickness is seriously reduced when heat-sealed, and the adhesion strength between the intermediate metal layer 13 and the heat-sealed resin layer 10 (in the case of adding a curing agent) is lowered, which causes a problem of sealability. If the weight average molecular weight exceeds 150000, the intermediate metal layer 13 and the heat-fusible resin layer 10 (in the case of the reaction of adding a curing agent) form a hard resin layer, and the flexibility of the metal composite film 1000 is lowered, or cracks are generated by bending, and the intermediate metal layer 13 and the heat-fusible resin layer 10 may be peeled off. If the acid value of the acid-modified polyolefin resin is less than 0.5mgKOH/g, the curing reaction point with the curing agent is small, and the adhesion between the intermediate metal layer 13 and the heat-fusible resin layer 10 is unstable. If the acid value exceeds 200mgKOH/g, the curing reaction between the curing agent and the acid-modified polyolefin resin becomes too severe, and a hard resin layer is formed, so that the flexibility of the metal composite film 1000 is lowered, or cracks are generated by bending, and the intermediate metal layer 13 and the heat-fusible resin layer 10 may be peeled off.

In some alternative embodiments, the first adhesive layer 11 is made from a hot melt adhesive, the first adhesive layer 11 containing acid modifying groups.

The resin used for the hot-melt type first adhesive layer 11 is an acid-modified polyolefin resin having a melting point of 135 to 165℃and an MFR (230 ℃) of 3 to 15g/10 min. The thickness of the hot-melt type first adhesive layer 11 formed is 2 to 80. Mu.m, preferably 5 to 50. Mu.m. The degree of modification of the acid-modified polyolefin resin used for the hot-melt first adhesive layer 11 is 1% to 15%, preferably 3% to 12%. When the melting point of the acid-modified polyolefin resin is 135 ℃ or lower, the resin fluidity becomes high by heating, the thickness becomes extremely thin in the case of pressure heat sealing, and the adhesion strength between the intermediate metal layer 13 and the heat-seal resin layer 10 becomes low, which causes a problem of sealability. When the melting point is 165 ℃ or higher, fluidity is relatively low at the time of heat sealing under pressure, heat resistance is improved, but when it is compounded with the intermediate metal layer 13, the heat shrinkage amount is increased, so that the internal stress is increased, and the adhesion ability of the heat-fusible type first adhesive layer 11 to the intermediate metal layer 13 is lowered. Therefore, if the intermediate metal layer 13 is peeled off during long-term storage, the intermediate metal layer may be peeled off. Further, heat shrinkage occurs due to heating during heat sealing, so that adhesion between the intermediate metal layer 13 and the intermediate metal layer is reduced, and sealing strength is lowered, which causes a great problem in sealability. If the MFR (230 ℃) of the acid-modified polyolefin resin is less than 3g/10min, the extrusion film-forming property tends to be unstable when the resin is compounded by hot-melt and then extruded onto the intermediate metal layer 13. If the MFR (230 ℃) of the acid-modified polyolefin resin is higher than 15g/10min, the resin fluidity becomes high by heating, the thickness becomes extremely thin at the time of pressure heat sealing, the adhesion strength between the intermediate metal layer 13 and the heat-sealing resin layer 10 becomes low, and there is a problem of sealability. When the thickness of the heat-fusible first adhesive layer 11 is less than 2 μm, the heat shrinkage cannot be absorbed because the heat shrinkage amount is excessive when it is compounded with the intermediate metal layer 13. Therefore, the adhesion force with the intermediate metal layer 13 decreases due to the increase of the internal stress. If the metal layer is stored for a long period of time, the metal layer may be peeled off from the intermediate metal layer 13. When the thickness of the hot-melt type first adhesive layer 11 exceeds 80. Mu.m, physical properties are not problematic, but the production cost is increased, so that the use is preferably avoided. When the degree of modification of the hot-melt type first adhesive layer 11 is less than 1%, the adhesion with the intermediate metal layer 13 is unstable. If the modification degree exceeds 15%, physical properties are not impaired, but the production cost is increased, so that it is preferable to avoid such a phenomenon.

[ First anticorrosive coating 12 ]

The first anticorrosive layer 12 prevents hydrogen fluoride generated by the reaction of the electrolyte and moisture from corroding the surface of the intermediate metal layer 13, prevents separation between the intermediate metal layer 13 and the heat-sealing resin layer 10, maintains uniformity of the surface of the intermediate metal layer 13, and has an effect of preventing delamination between the intermediate metal layer 13 and the heat-sealing resin layer 10 with little change in adhesiveness (wettability) in the packaging material for lithium ion batteries.

The outer packaging material for the lithium ion battery device on the market at present can select anti-corrosion liquid with different components according to the type of the first adhesive layer, and the production efficiency is low, and the production cost is high.

In the present application, the first adhesive layer 11 includes an acid-modified group and/or an isocyanate group, the first anticorrosive layer 12 includes a nitrogen-containing polymer having an amine group that reacts with the acid-modified group and/or the isocyanate group in the first adhesive layer 11, and the content of nitrogen atoms in the first anticorrosive layer 12 is greater than 0 and 20At% or less.

The nitrogen-containing polymer includes, but is not limited to, at least one of polyurethane, polyacrylamide, urea resin, amine-based resin, melamine, etc., as long as it contains an amine group capable of reacting with an acid modifying group. When the first adhesive layer 11 includes isocyanate groups, the amino groups (NH ₂) in the nitrogen-containing polymer may react with the isocyanate groups (NCO) in the first adhesive layer 11 to generate urea groups; when the first adhesive layer 11 includes acid modifying groups, the amino groups (NH ₂) in the nitrogen-containing polymer may react with the acid modifying groups in the first adhesive layer 11 to form an amino compound. Both reactions have covalent bonding, whereby a strong adhesion is achieved.

That is, according to the present application, the amine group of the nitrogen-containing polymer used in the first anticorrosive layer 12 can react with the acid-modified group and/or the isocyanate group in the first adhesive layer 11, and the content of the nitrogen atom in the first anticorrosive layer is controlled, so that not only can the first anticorrosive layer 12 and the first adhesive layer 11 be combined through covalent bonds, thereby effectively improving the adhesion between the two, but also the connection between the intermediate metal layer 13 and the heat-sealing resin layer 10 is further improved, thereby improving the initial peel strength between the intermediate metal layer 13 and the heat-sealing resin layer 10 of the metal composite film 1000, and the corrosion resistance in the environment of an anhydrous and water electrolyte, not only realizing the long-term stability when the metal composite film 1000 is used as an exterior packaging material for a lithium ion battery device, but also the first anticorrosive layer 12 can be adapted to different types of the first adhesive layers (solvent type adhesive and heat-sealing adhesive), thereby being beneficial for improving the production efficiency and reducing the production cost of the metal composite film 1000.

In some alternative embodiments, the first corrosion protection layer 12 has a nitrogen atom content of 1At% to 20At%.

Controlling the content of nitrogen atoms in the first anticorrosive layer 12 within the above-described range is advantageous in improving the peel strength between the first anticorrosive layer 12 and the first adhesive layer 11.

Illustratively, the content of nitrogen atoms in the first corrosion prevention layer 12 is any one value or between any two values of 1At%, 3At%, 5At%, 8At%, 10At%, 13At%, 15At%, 18At%, 20 At%.

In some alternative embodiments, the first corrosion protection layer is formed from a corrosion protection liquid by coating and heat treatment from the corrosion protection liquid; wherein the mass percentage of the nitrogen-containing polymer in the anti-corrosion liquid is 0.1% -3%.

The mass percentage of the nitrogen-containing polymer in the anti-corrosion liquid is controlled to be 0.1% -3.0%, so that the first anti-corrosion layer can correspond to different types of first adhesive layers (solvent type adhesive and hot melt adhesive) and can be combined through covalent bonds, the connection between the intermediate metal layer 13 and the hot melt resin layer 10 is firm, and the peeling strength and the stability of the adhesive are effectively improved.

Illustratively, the nitrogen-containing polymer is present in the corrosion protection liquid at a mass percent of any one or between any two of 0.1%, 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%.

The outer packaging material for the lithium ion battery device on the market at present can select anti-corrosion liquid with different components according to the type of the first adhesive layer, and the production efficiency is low, and the production cost is high. The nitrogen-containing polymer can respectively carry out covalent bond combination reaction with the solution type first adhesive and the hot melt type first adhesive, and meanwhile, the addition amount of the nitrogen-containing polymer is in the range, so that the combination of the first anti-corrosion layer and the first adhesive layer formed by the two first adhesives has long-term stable composite performance, and the stability of the peeling strength is kept when electrolyte permeates.

In some alternative embodiments, at least one of the carboxylic acid-containing polymer, the hydroxy acrylic resin and the cross-linking agent is further included in the anti-corrosion liquid, wherein the mass percentage of the carboxylic acid-containing polymer in the anti-corrosion liquid is 0.1% -2.0%, the mass percentage of the hydroxy acrylic resin in the anti-corrosion liquid is 0.1% -2.0%, and the mass percentage of the cross-linking agent in the anti-corrosion liquid is 0.5% -5%.

The main chain of the nitrogen-containing polymer is easy to break under a long period, and the carboxylic acid-containing polymer can alleviate the failure of nitrogen under the long period, passivate nitrogen atoms, inhibit the main chain of the nitrogen-containing polymer from breaking under the long period, and is beneficial to improving the long-acting performance of the metal composite film.

The hydroxyl acrylic resin can assist in improving the durability of the material, and can assist in the nitrogen-containing polymer, so that the hydroxyl acrylic resin can react with the first adhesive layer 11 formed by the crosslinking agent of the first anti-corrosion layer 12 and the solution-type adhesive, the crosslinking density of the first anti-corrosion layer 12 is improved, and the overall long-acting property is improved.

The addition of the crosslinking agent can increase the crosslinking density of the first anticorrosive layer 12, stabilize the first anticorrosive layer 12 against hydrogen fluoride generated by the electrolyte solution and the reaction of the electrolyte solution with water as the contents, and can suppress the problems of the excessive hardening of the first anticorrosive layer 12 due to the excessive addition amount of the crosslinking agent, the cracking and peeling of the anticorrosive layer, and the decrease in corrosion resistance during the molding process.

The application is beneficial to improving the overall long-acting performance by controlling the introduction and the addition proportion of each component in the reasonable range.

Illustratively, the mass percent of the carboxylic acid-containing polymer in the corrosion protection liquid is any one of or between any two of 0.1%, 0.5%, 1.0%, 1.5%, 2.0%.

Illustratively, the mass percent of the hydroxy acrylic resin in the anti-corrosion liquid is any one of, or between, 0.1%, 0.5%, 1.0%, 1.5%, 2.0%.

Illustratively, the cross-linking agent is present in the anti-corrosion liquid at a mass percent of any one or between any two of 0.5%, 1.0%, 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%.

Optionally, the anti-corrosion liquid comprises carboxylic acid-containing polymer, hydroxy acrylic resin and cross-linking agent.

By introducing the carboxylic acid-containing polymer, the hydroxy acrylic resin and the crosslinking agent at the same time, the direct bonding stability of the first adhesive layer 11 and the first corrosion prevention layer 12 is improved, so that the decrease of the bonding force is inhibited and the stability of the peeling strength is ensured when the electrolyte permeates. In some alternative embodiments, the carboxylic acid-containing polymer has a carbon chain with no more than 5 carbon atoms apart from the carboxyl group.

After the carboxyl groups are combined with the nitrogen-containing polymer, the carboxyl groups on the carbon chain of the carboxylic acid-containing polymer are controlled to have a carboxyl group interval of not more than 5 carbon atoms, and the carbon atoms (C) cannot rotate randomly due to the higher carboxyl group density on the carbon chain, so that the amino groups in the nitrogen-containing polymer are relatively stabilized, the main chain is not easy to break under a long period, and the long-acting performance of the first anti-corrosion layer 12 is improved.

Illustratively, carboxylic acid-containing polymers having carboxyl groups spaced no more than 5 carbon atoms apart on the carbon chain include, but are not limited to, polyacrylic acid and the like.

In some alternative embodiments, the carboxylic acid-containing polymer comprises a phosphonocarboxylic acid copolymer.

The phosphonocarboxylic acid copolymer not only can be used as an amino protective agent, but also has excellent dispersion performance, and can effectively improve the long-acting performance of the first anti-corrosion layer 12.

In some alternative embodiments, the crosslinking agent includes at least one of an epoxy compound, an oxazoline compound, and an adipic acid dihydrazide compound.

By adding the crosslinking agent, the crosslinking density of the first anticorrosive layer 12 can be increased, and the resistance of the first anticorrosive layer 12 to the electrolyte solution as the content and hydrogen fluoride generated by the reaction of the electrolyte solution with water can be stabilized.

In some alternative embodiments, the anticorrosive liquid further comprises a trivalent metal compound, an inorganic acid and an organic resin, wherein the trivalent metal compound is a trivalent chromium compound or a trivalent cerium compound, the trivalent metal compound accounts for 1.9% -6% of the anticorrosive liquid by mass, the inorganic acid accounts for 0.3% -6% of the anticorrosive liquid by mass, and the organic resin accounts for 0.6% -6% of the anticorrosive liquid by mass.

Wherein the organic resin is composed of polyacrylic resin and/or polyvinyl alcohol, and the polyacrylic resin is one or more of polyacrylic acid, polymethyl acrylate, copolymer of acrylic acid and maleic acid, copolymer of acrylic acid and styrene and sodium salt and ammonium salt derivatives thereof.

The organic resin is illustratively composed of at least one of an acrylic resin, a methacrylic resin, a hydroxyacrylic resin, a polyvinyl alcohol resin, an olefin resin, and a phenolic resin.

Wherein, the trivalent chromium compound in the anti-corrosion liquid at least comprises one of chromium nitrate, chromium phosphate, chromium chloride and chromium fluoride; the trivalent cerium compound is at least one of cerium nitrate, cerium phosphate and cerium chloride; wherein, trivalent metal compound can react with phosphono carboxylic acid copolymer, forms stable complex, promotes the long-term performance of first anticorrosion layer.

Optionally, the trivalent chromium compound is one of chromium nitrate and chromium fluoride. Chromium nitrate and chromium fluoride can react with resin, an intermediate metal layer and inorganic acid in the first anti-corrosion layer, and the chromium fluoride can improve the hydrogen fluoride resistance of the first anti-corrosion layer, and can ensure the stability of the peeling strength of the heat welding resin layer and the intermediate metal layer during long-term storage.

Wherein the inorganic acid is at least one of nitric acid and phosphoric acid. 21. The inorganic acid can remove the surface oxide film of the intermediate metal layer, so that the metal can quickly react with the components in the anti-corrosion layer to form firm chromium reaction products. This ensures the peel strength stability between the thermally fused resin layer and the intermediate metal layer when the composite film is stored for a long period of time.

Illustratively, the mass percent of the trivalent metal compound in the corrosion protection liquid is any one of, or between, 1.9%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%.

The inorganic acid is exemplified by any one or between any two of 0.3%, 1%, 2%, 3%, 4%, 5%, 6% by mass in the anticorrosive liquid.

The mass percentage of the organic resin in the anticorrosive liquid is, for example, any one value or between any two values of 0.6%, 1%, 2%, 3%, 4%, 5%, 6%.

In some alternative embodiments, the corrosion protection liquid includes a titanium compound or a zirconium compound, wherein the titanium compound is 0-0.6% by mass of the corrosion protection liquid, and the zirconium compound is 0-2.8% by mass of the corrosion protection liquid.

The titanium compound or the zirconium compound can improve the stability and uniformity of the reaction of chromium with resin, metal and inorganic acid. Wherein the titanium compound is at least one of titanium fluoride and titanium nitrate, and the zirconium compound is at least one of zirconium fluoride and zirconium nitrate.

Illustratively, the mass percent of the titanium compound in the corrosion protection liquid is any one of 0%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6% or between any two values, and the mass percent of the zirconium compound in the corrosion protection liquid is any one of 0%, 0.1%, 0.3%, 0.5%, 0.8%, 1.0%, 1.3%, 1.5%, 1.7%, 2.0%, 2.3%, 2.5%, 2.8% or between any two values.

It is to be understood that the anticorrosive liquid may contain a solvent in addition to the above-mentioned nitrogen-containing polymer, carboxylic acid-containing polymer, hydroxyacrylic acid resin, crosslinking agent, and the like, wherein the mass percentage of each component and solvent is 100%. The solvent is an organic solvent, water or a mixture of water and an organic solvent, that is, the organic solvent can be used alone as a solvent or can be added into water. The wettability of the anti-corrosion liquid can be improved, and the reaction stability of the first anti-corrosion layer and the intermediate metal layer can be improved. In addition, the surface tension of the anticorrosive liquid can be reduced, and the uniformity of the coating film can be improved. As the organic solvent, one selected from isopropanol, ethanol and ethylene glycol butyl ether may be used.

Illustratively, the solvent is present in the corrosion protection fluid at a mass percent of 78.6-97.2%.

The method of coating the anti-corrosion liquid may include: first, degreasing treatment is performed on at least the heat-sealed resin layer of the intermediate metal layer by treatment methods such as an alkali impregnation method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an oxygen activation method, and a heat treatment (annealing treatment) during rolling. Secondly, the used anti-corrosion liquid is coated by a bar coating method, a roll coating method, a gravure coating method, a dipping method and the like, a high-temperature chemical combination reaction is acted on the surface of the intermediate metal layer, the coating wet film amount of the anti-corrosion liquid on the intermediate metal layer 13 is 1.6-3.2g/m ², and the anti-corrosion layer is formed by heat treatment for 0.5-5min at the high temperature of 130-200 ℃ after the anti-corrosion liquid is coated.

The thickness of the first anticorrosive layer 12 is not particularly limited, but is preferably 1nm to 3.0 μm, more preferably 1nm to 1.5 μm, from the viewpoint of adhesion force between the intermediate metal layer 13 and the heat-fusible resin layer.

[ Intermediate Metal layer 13]

The intermediate metal layer 13 serves as a barrier layer that can at least inhibit moisture from entering the metal composite film 1000 during use.

The metal material used for the intermediate metal layer 13 may be, specifically, an aluminum alloy, stainless steel, titanium steel, nickel-plated steel sheet, or the like.

In some alternative embodiments, the intermediate metal layer 13 is a nickel-plated steel sheet. When the intermediate metal layer 13 is a nickel-plated steel sheet, the nickel-plated layer has an anticorrosive effect such as rust prevention and the like, and also has an effect of improving the surface cleanliness. By forming an anti-corrosion layer described later on the nickel-plated surface, the anti-corrosion property of the nickel-plated layer and the synergistic effect with the anti-corrosion layer are dramatically improved in electrolyte resistance. The thickness of the nickel plating layer is not more than 20. Mu.m. Preferably 1 μm or more and 5 μm or less. If the particle diameter exceeds 20. Mu.m, the corrosion resistance is improved, but cracks are likely to occur due to an external pressure load such as molding.

In addition, the surface cleanliness of the intermediate metal layer 13 greatly affects the corrosion prevention effect, and therefore, the management of the surface cleanliness of the intermediate metal layer 13 becomes important. Surface cleanliness can be managed by a method using wettability by a wetting agent test or a method using contact angle as an index. The wettability is preferably class D or higher, preferably class B. The contact angle is 25 ° or less, preferably 20 ° or less, and more preferably 15 ° or less when measured with pure water. When the wettability is lower than D level or the contact angle exceeds 25 °, the reactivity with an anti-corrosion layer to be described later or the initial adhesion is deteriorated. If the reactivity is deteriorated, the reaction between the first anticorrosive layer 12/second anticorrosive layer 14 and the intermediate metal layer 13 becomes insufficient, and the permeation resistance to the electrolyte solution as the battery content and the resistance to hydrogen fluoride generated in the reaction between the electrolyte and water are reduced. Over time, the adhesion of the first corrosion prevention layer 12/second corrosion prevention layer 14 to the intermediate metal layer 13 decreases, and the first corrosion prevention layer 12/second corrosion prevention layer 14 dissolves, and the intermediate metal layer 13 and the first/second corrosion prevention layer 14 may peel off, thereby shortening the life of the battery. The same occurs when the initial adhesion between the first anticorrosive layer 12, the second anticorrosive layer 14, and the intermediate metal layer 13 is deteriorated.

The method for testing the wettability of the surface of the intermediate metal layer 13 can adopt the method for testing metals in national standard GB/T225638.5-2016 of the people's republic of China, part 5: and (3) detecting wettability. The contact angle test method of the intermediate metal layer 13 can adopt the national standard GB/T22638.9-2008 of the people's republic of China, the 9 th part of the metal test method: measurement of hydrophilicity).

[ Second anticorrosive coating 14 ]

The second anticorrosive layer 14 is located between the second adhesive layer 15 and the intermediate metal layer 13 for preventing separation between the intermediate metal layer 13 and the external resin layer.

The composition of the second anticorrosive layer 14 may be the same as or different from the composition of the first anticorrosive layer 12, and preferably the composition of the second anticorrosive layer 14 may be the same as the composition of the first anticorrosive layer 12.

The thickness of the second corrosion protection layer 14 may be the same as or different from the thickness of the first corrosion protection layer 12, and may be set by those skilled in the art according to actual needs.

[ Second adhesive layer 15]

The second adhesive layer 15 is a layer formed for the purpose of improving the adhesion between the outer base resin layer 16 and the intermediate metal layer 13, and the like.

The second adhesive layer 15 is formed of an adhesive capable of adhering the outer base resin layer 16 and the intermediate metal layer 13. The adhesive used for forming the second adhesive layer 15 is not limited, and may be, for example, a two-component curable adhesive (two-component adhesive), or may be a one-component curable adhesive (one-component adhesive). The adhesive used in forming the second adhesive layer 15 may be any of a chemical reaction type, a solvent evaporation type, a hot melt type, a hot press type, and the like. The second adhesive layer 15 may be a single layer or a plurality of layers.

The composition of the second adhesive layer 15 may be the same as or different from that of the first adhesive layer 11, and the second adhesive layer 15 is usually a two-component polyurethane adhesive formed by using a polyester polyol, a polyurethane-modified polyol, or the like as a diol main agent, and an aromatic or aliphatic isocyanate as a curing agent. The curing agent may be selected according to the functional group of the adhesive component, and may be appropriately selected from, for example, a polyfunctional epoxy resin, a polymer containing methanesulfonic acid, a poislamine resin, an inorganic acid, and the like. In addition, the main agent used for the outer adhesive layer is polyester resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and copolyester; a polyether resin; a polyurethane resin; an epoxy resin; a phenolic resin; polyamide resins such as nylon 6, nylon 66, nylon 12, and copolyamide; polyolefin resins such as polyolefin, cyclic polyolefin, acid-modified polyolefin and acid-modified cyclic polyolefin; polyvinyl acetate; cellulose; (meth) acrylic resin; polyimide resin; a polycarbonate; amino resins such as urea resin and melamine resin; rubber such as neoprene rubber, nitrile rubber, and styrene-butadiene rubber; silicone resins, and the like. These adhesive components may be used singly or in combination of two or more.

More preferred combinations of the second adhesive layer 15 in the present application are one or two of a binary or a multi-element polyester, a polyurethane modified polyester, and an isocyanate. The isocyanate is not particularly limited to a compound having two or more isocyanate groups in a molecule. For example, isophorone diisocyanate (IPDI), toluene Diisocyanate (TDI), diphenylmethane-4, 4 ^, -diisocyanate (MDI), 1, 6-Hexamethylene Diisocyanate (HDI) and the like.

In some alternative embodiments, the second corrosion protection layer 14 includes a nitrogen-containing polymer having amine groups and the second adhesive layer 15 includes acid modifying groups and/or isocyanate groups that react with the amine groups.

The specific components of the second corrosion protection layer 14 may refer to the arrangement of the first corrosion protection layer 12, which is not described herein. The acid modifying group includes, but is not limited to, at least one of a carboxyl group, a sulfonic acid group, a maleic acid group, a sulfinic acid group, a sulfenate group, a phosphoric acid group, a phosphonic acid group, and the like.

The second adhesive layer 15 may contain a colorant, a thermoplastic elastomer, a tackifier, a filler, and the like, as long as the adhesion is not impaired.

In some alternative embodiments, the second adhesive layer 15 contains a colorant. The second adhesive layer 15 contains a colorant, whereby the lithium ion battery packaging material can be colored. As the colorant, a colorant such as a pigment or a dye can be used. The colorant may be used alone or in combination of two or more.

The type of pigment is not particularly limited as long as the adhesiveness of the second adhesive layer 15 is not impaired. Examples of the organic pigment include azo pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, dioxazine pigments, thioindigo pigments, perylene pigments, isoindoline pigments, and the like; as the inorganic pigment, carbon black pigments, titanium oxide pigments, cadmium pigments, lead pigments, isoindoline pigments, and the like can be used.

Among the colorants, carbon black is preferable, for example, for making the appearance of the lithium ion battery packaging material black.

The average particle diameter of the pigment is not particularly limited, and may be about 0.05 to 5. Mu.m, preferably about 0.08 to 2. Mu.m. The average particle diameter of the pigment is the median particle diameter measured by a laser diffraction/scattering particle diameter distribution measuring device.

The pigment content in the second adhesive layer 15 is not particularly limited as long as the lithium ion battery packaging material is colored, and is preferably about 5 to 60%, more preferably 10 to 40%.

The thickness of the second adhesive layer 15 is not particularly limited as long as it can bond the outer base resin layer 16 and the intermediate metal layer 13, and a preferable range thereof is about 1 to 10 μm, and more preferably about 2 to 5 μm.

[ External base resin layer 16 ]

When the metal composite film 1000 is used as a packaging material for lithium ion batteries, the outer base resin layer 16 is located on the outer layer side of the packaging material for lithium ion batteries. The outer base resin layer 16 is provided so as to be able to function as a base material for a lithium ion battery packaging material.

The material for forming the outer base resin layer 16 is not particularly limited, as long as it has at least insulation properties.

There are various methods for producing the outer base resin layer 16. For example, the resin film may be formed directly from a resin, or the resin film may be coated. The resin film may be an unextended film or an extended film. The stretched film may be a one-axis stretched film or a two-axis stretched film, and is preferably a two-axis stretched film. Examples of the method for producing the biaxially stretched film include a stepwise biaxial stretching method, a blown film method, and a simultaneous stretching method. Examples of the resin coating method include a roll coating method, a gravure coating method, and an extrusion coating method.

As the resin forming the outer base resin layer 16, for example, a resin such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, phenolic resin, or the like, or a modified product of these resins is used. The resin forming the outer base resin layer 16 may be a copolymer of these resins, a modified copolymer, or a mixture of these resins, and a single layer or a plurality of layers is preferable.

Among these, the resin forming the outer base resin layer 16 is preferably polyester or polyamide.

Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and a copolyester. Further, as the copolyester, a copolyester having ethylene terephthalate as a main unit, and the like can be mentioned. Specifically, a copolymer polyester (hereinafter simply referred to as a copolyester (terephthalate/isophthalate)), a copolyester (terephthalate/adipate), a copolyester (terephthalate/sodium isophthalate), a copolyester (terephthalate/phenyl-dicarboxylate), a copolyester (terephthalate/decanedicarboxylate), or the like, which is obtained by polymerizing ethylene terephthalate as a main body of a repeating unit with ethylene isophthalate. These polyesters may be used singly or in combination of two or more.

Specific examples of the polyamide include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; aromatic polyamides such as hexamethylenediamine-isophthalic acid-terephthalic acid copolyamide (such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (wherein I represents isophthalic acid, and T represents terephthalic acid)) and polyamide MXD6 (such as polyamide PACM6 (poly-bis (4-aminocyclohexyl) methane azide amide)) containing structural units derived from terephthalic acid and/or isophthalic acid.

The outer base resin layer 16 preferably contains at least one of a polyester film, a polyamide film, and a polyolefin film; preferably at least one of a stretched polyester film, a stretched polyamide film and a stretched polyolefin film; further preferably comprises at least one of a stretched polyethylene terephthalate film, a stretched polybutylene terephthalate film, a stretched nylon film, a stretched polypropylene film; further preferably comprises at least one of biaxially oriented polyethylene terephthalate film, biaxially oriented polybutylene terephthalate film, biaxially oriented nylon film, biaxially oriented polypropylene film.

The outer base resin layer 16 may be a single layer or may be composed of two or more layers. When the outer base resin layer 16 is composed of two or more layers, the outer base resin layer 16 may be a composite film formed by the action of an adhesive, or may be a resin composite film formed by coextruding resins. In addition, the outer base resin layer 16 may be formed by coextrusion of a resin to form two or more resin composite films in an unstretched state, or may be formed by uniaxial stretching or biaxial stretching to be used as the outer base resin layer 16.

Specific examples of the laminate of two or more resin films in the outer base resin layer 16 include a composite film of a polyester film and a nylon film, a composite film of two or more nylon films, and a composite film of two or more polyester films. Preferably, the stretched nylon film and the stretched polyester film are laminated, a stretched nylon composite film of two or more layers, and a stretched polyester composite film of two or more layers. For example, when the outer base resin layer 16 is a two-layer resin composite film, a composite film of a polyester resin film and a polyester resin film, a composite film of a polyamide resin film and a polyamide resin film, or a composite film of a polyester resin film and a polyamide resin film is preferable, and more preferable is a composite film of a polyethylene terephthalate film and a polyethylene terephthalate film, a composite film of a polybutylene terephthalate film and a polybutylene terephthalate film, a composite film of a nylon film and a nylon film, or a composite film of a polyethylene terephthalate film and a nylon film. Further, since the polyester resin is less likely to be discolored when the electrolyte is adhered to the surface, when the outer base resin layer 16 is a resin composite film of two or more layers, it is preferable that the polyester resin film is located at the outermost layer of the outer base resin layer 16.

When the outer base resin layer 16 is a resin composite film of two or more layers, the two or more layers of resin films may be combined by an adhesive. As a preferable adhesive, a glue solution having the same composition as the outer layer adhesive can be used. The method for compounding two or more resin films is not particularly limited, and a dry compounding method, an interlayer compounding method, an extrusion compounding method, a thermal compounding method, or the like can be used, and a dry compounding method is preferable. When the lamination is performed by a dry lamination method, a reactive polyurethane adhesive is preferably used as the reactive adhesive for the outer layer. At this time, the thickness of the adhesive layer may be about 2 to 5 μm. When the outer base resin layer 16 is formed by the resin coating method, the outer base resin layer 16 may be formed by dissolving a resin in an organic solvent and coating the resin. As the coating resin, a polyamide resin, a polyimide resin, a polyurethane resin, an epoxy resin, an acrylic resin, a polyester resin, a phenol resin such as a polyamide resin, a polyimide resin, a fluorine-based copolymerization resin, a polyester resin, and an amino resin such as a polyester resin, a polycarbonate resin, a urea resin, and a melamine resin can be used.

In addition, one or more of additives such as lubricants, flame retardants, antiblocking agents, antioxidants, light stabilizers, tackifiers, antistatic agents, and the like may be added to the surface and the inside of the outer base resin layer 16.

From the viewpoint of improving the formability of the lithium ion battery packaging material, it is preferable to form a layer made of a lubricant on the surface of the outer base resin layer 16. The lubricant is not particularly limited, and an amide-based lubricant is preferable. The amide type lubricant includes saturated fatty acid amide, unsaturated fatty acid amide, substituted amide, methylol amide, saturated fatty acid bisamide, unsaturated fatty acid bisamide, fatty acid amide, aromatic bisamide, and the like. As the saturated fatty acid amide, lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide and the like can be used. Examples of the unsaturated fatty acid amide include oleic acid amide and erucic acid amide. Substituted amides include N-oil palmitoyl amide, N-stearyl amide, N-oil stearyl amide, and N-stearyl amide. In addition, methylolamides include methylol stearic acid amide and the like. Saturated fatty acid bisamides include methylene bisstearamide, ethylene bisoctanoate amide, ethylene bislaurate amide, ethylene bisstearate amide, ethylene bishydroxystearate amide, ethylene bisbehenate amide and hexamethylene bisstearate hexamethylenebisbehenate amide, hexamethylenehydroxystearate amide, n ^, -distearyl adipate amide, n ^, -distearyl sebacate amide and the like. Unsaturated fatty acid bisamides include ethylene bis-oleamide, ethylene bis-erucamide, hexamethylene bis-oleamide, n ^, -dioleyladipamide and n, n ^, -dioleylsebacamide. Fatty acid ester amides include stearamide ethyl stearate and the like. The aromatic bisamide includes m-xylylene bisstearamide, m-xylylene bishydroxystearamide, n ^, -distearyl isophthalic acid amide, and the like. The lubricant may be used alone or in combination of two or more.

When a lubricant is present on the surface of the outer base resin layer 16, the coating amount is not particularly limited, and is preferably about 3mg/m ² or more, more preferably about 4 to 30mg/m ².

The lubricant present on the surface of the outer base resin layer 16 may be a lubricant oozed out from the base resin layer containing the lubricant, or may be a lubricant applied to the surface of the outer base resin layer 16.

The thickness of the outer base resin layer 16 is not particularly limited as long as it functions as a base material. When the outer base resin layer 16 is a resin composite film of two or more layers, the thickness of the resin film constituting each layer is preferably about 2 to 30 μm.

In the present application, the outer substrate resin layer 16 may be a single layer or a composite film of two or more layers formed of one or more materials selected from the group consisting of blown nylon, synchronous or asynchronous biaxially oriented polyethylene terephthalate (PET), synchronous or asynchronous biaxially oriented polybutylene terephthalate (PBT), polyimide (PI), and the like, the outer substrate resin layer 16 may be bonded to the intermediate metal layer 13 by one or a combination of extrusion, coating, lamination, and heat bonding, and the total thickness of the outer substrate resin layer 16 is 5 to 35 μm. When the thickness is less than 5. Mu.m, the moldability and insulation properties are relatively poor. In addition, if it exceeds 35 μm, the total thickness of the metal composite film 1000 becomes too thick, and the metal composite film 1000 is deteriorated in flexibility, which is an advantage.

[ Colorant layer 17 ]

The colored layer 17 is a layer which is provided between the outer base material resin layer 16 and the second adhesive layer 15 as necessary in the colored layer 17, or the colored layer 17 is provided on the side of the outer base material resin layer 16 facing away from the intermediate metal layer 13, so that the appearance of the metal composite film 1000 is a predetermined color.

The coloring layer 17 contains a pigment, a dye, or the like as a colorant. The colorant may be used alone or in combination of two or more.

As a specific example of the colorant contained in the coloring layer 17, an example of the second adhesive layer 15 can be referred to.

[ Metal composite Membrane 1000 composite Process ]

1. Deoiling treatment of the intermediate metal layer 13:

The surface wettability of the intermediate metal layer 13 is 65dyn/cm, preferably 70dyn/cm or more, or the titration contact angle of distilled water is 15 degrees or less, preferably 10 degrees or less. If the wettability or surface water contact angle of the intermediate metal layer 13 exceeds a given range, there is a possibility that the rolling oil still remains on the metal at the production stage, and therefore, the interfacial adhesion ability formed between the first anticorrosive layer 12, the intermediate metal layer 13 and the heat-fusible resin layer 10 becomes poor, and there is a risk that the battery is likely to leak from the intermediate metal layer 13 and the heat-fusible resin layer 10 during long-term storage of the battery, and as a preventive measure thereof, annealing treatment at 150 ℃ or more may be performed, and deoiling may be performed by plasma, corona, alkali solution, or alkali deoiling is performed by immersing the metal in an alkali solution at 50 to 65 ℃ for a certain period of time, washing with deionized water 2 times, and then drying to obtain deoiled metal.

2. Formation of the first/second anticorrosive layer 14 on the intermediate metal layer 13:

After the surface of the intermediate metal layer 13 is coated with the anticorrosive liquid, the first/second anticorrosive layer 14 is formed by heat treatment at a high temperature for a certain period of time.

3. Formation and compounding of the second adhesive layer 15:

The polyurethane adhesive dissolved in an organic solvent is applied between the intermediate metal layer 13 and the outer base material resin layer 16, the polyurethane adhesive is heated at a certain temperature for a certain time to volatilize the organic solvent, a second adhesive layer 15 is formed, the outer base material resin layer 16, the second adhesive layer 15 and the intermediate metal layer 13 are further compounded at a certain temperature and pressure, and after a certain time of storage treatment at a certain temperature, the second adhesive layer 15 is subjected to a curing reaction, so that a composite resin layer composed of the outer base material resin layer 16, the second adhesive layer 15 and the intermediate metal layer 13 is obtained. When the second adhesive is not used for the compounding of the outer base material resin layer 16 and the intermediate metal layer 13, the intermediate metal layer 13 and the outer base material resin layer 16 are compounded by heating and pressurizing, and the outer base material resin layer 16 is subjected to a heat treatment, an ultraviolet treatment, and an electron beam treatment to form a film, thereby obtaining a composite resin layer composed of the outer base material resin layer 16 and the intermediate metal layer 13.

4. Compounding of the heat fusion resin layer 10: the composite film composed of the outer base resin layer 16 and the intermediate metal layer 13 may be appropriately selected to be composited with the heat fusion resin layer 10 in different compositing manners, and the following is exemplified:

a. Dry compounding method: the solution type first adhesive layer composed of a main agent, a curing agent and an organic solvent is coated on the corrosion-resistant surface of the intermediate metal layer 13 of the composite film composed of the outer base material resin layer 16 and the intermediate metal layer 13, the solution type first adhesive is dried to form the first adhesive layer 11, and the first adhesive layer is thermally compounded with the bonding surface of the thermal welding resin layer 10 at a certain temperature and pressure, and then the curing treatment is carried out, so that the composite product of the outer base material resin layer 16/the intermediate metal layer 13/the first adhesive layer 11/the thermal welding resin layer 10 is formed. It is preferable that the bonding surface of the heat fusion resin layer 10 in contact with the first adhesive layer 11 is corona-treated in advance. In addition, curing treatment at a temperature of 60 ℃ not exceeding the melting point temperature of the first adhesive layer 11 may be performed;

b. Melt extrusion process: the resin for the hot-melt type first adhesive layer forms the hot-melt type first adhesive layer 11 having a certain thickness on the corrosion-resistant surface of the intermediate metal layer 13 by melt extrusion. The surface of the first adhesive layer 11 and the adhesive surface of the heat-sealed resin layer 10 are thermally combined to form a composite product of the outer base resin layer 16, the intermediate metal layer 13, the first adhesive layer 11, and the heat-sealed resin layer 10. In order to improve the peeling force between the intermediate metal layer 13 and the heat-sealing resin layer 10, a heat treatment of not more than 60 ℃ of the melting point temperature of the first adhesive layer 11 may be performed;

c. Melt extrusion process: the hot-melt type first adhesive layer 11 and the hot-melt type resin layer 10 form a composite product of the outer base resin layer 16/the intermediate metal layer 13/the first adhesive layer 11/the hot-melt type resin layer 10 by means of a coextrusion method. After the surface of the intermediate metal layer 13 in contact with the first adhesive layer 11 is subjected to the corrosion-preventing treatment, a heat treatment at a temperature of 60 ℃ not exceeding the melting point temperature of the first adhesive layer 11 may be performed in order to improve the peeling force between the intermediate metal layer 13 and the heat-sealing resin layer 10;

d. Thermal bonding method: the resin main agent and the curing agent with the melting point of more than 100 ℃ are dissolved in an aqueous or organic solvent to form the aqueous solution type first adhesive. The solution type first adhesive is dried on the metal layer corrosion-resistant treated surface of the composite layer composed of the outer base resin layer 16 and the intermediate metal layer 13 to form the first adhesive layer 11. And thermally compounding with the bonding surface of the thermal welding resin layer 10 at a certain temperature and pressure to form a composite product of the outer base material resin layer 16/the intermediate metal layer 13/the first adhesive layer 11/the thermal welding resin layer 10. In order to improve the peeling force between the intermediate metal layer 13 and the heat fusion resin layer 10, a heat treatment of not more than 60 ℃ of the melting point temperature of the first adhesive layer 11 may be performed. The heat-fusible resin layer 10 may be molded by extrusion, or a film may be used, and when a film is used, it is preferable that the adhesive surface of the heat-fusible resin layer 10 in contact with the first adhesive layer 11 is corona-treated in advance.

The application also provides an electrochemical device using the metal composite film.

Electrochemical devices include, but are not limited to, batteries including, but not limited to, lithium ion batteries, sodium ion batteries, and the like. That is, the metal composite film can be applied to an electrochemical device as a battery outer packaging material.

The present application will be described in detail by examples.

1. Parameter determination

(1) Water contact Angle measurement

Using a German KRUSSDSA contact angle measuring instrument to measure the water contact angle of the surface of the metal intermediate layer, flatly placing the metal intermediate layer on an instrument workbench, controlling the water yield of the injector to be 2 mu mL each time, controlling the liquid adding speed to be 2.67 mu mL/s, and recording the contact angle value of the water drop just dropped on the surface of the metal intermediate layer;

(2) Determination of the dyne value

Continuously drawing 2 straight lines with the length of 10cm on the surface of the metal intermediate layer by using a German Arcotest dyne pen, if the straight line is contracted by more than 10% within 3 seconds, indicating that the dyne value of the surface of the metal intermediate layer cannot reach the dyne value of the dyne pen at the moment, and re-measuring by selecting the dyne pen with the low dyne value;

(3) Element determination of corrosion protection layer

The element distribution of the first/second anticorrosive layer depth of the metal interlayer surface was measured by ESCA method using XPS (shimadzu, AXIS supra). Ar ion sputtering sample metal surface, ion beam diameter of 800 μm, voltage of 15KV, ion beam sputtering depth of 5nm, sputtering rate of 3nm/min, sputtering times of 7 times, signal source detection depth of 5nm, detection limit of 1 mill, and detection times of 8 times.

2. The peel strength between the intermediate metal layer and the heat-fusible resin layer of the metal composite film finished product was tested as follows.

(1) Initial peel strength test

Preparing a metal composite film finished product into a straight strip shape, wherein the spline size is 100 mm or 15mm, using a tensile test device to perform interlayer peeling test on an intermediate metal layer and a heat welding resin layer, placing the peeled heat welding resin layer film in an upper clamping plate of a telescopic test device, placing the intermediate metal layer in a lower clamping plate, then performing T-shaped peeling with a peeling surface of 180 degrees under the condition that the telescopic speed is 50mm/min, and starting to measure the peeling strength between the intermediate metal layer and the heat welding resin layer. The peel strength is read by selecting an average value of peel strength between 10mm and 40 mm when the moving distance of the heat-welding resin layer and the intermediate metal layer is 50 mm. 5/group were tested in parallel.

(2) Anhydrous electrolyte resistance test of metal composite film finished product

Directly soaking the metal composite film finished product sample strip in dimethyl carbonate (DMC) containing 1mol/L LiPF ₆: diethyl carbonate (DEC): the mass ratio of the Ethylene Carbonate (EC) material was 1:1:1, soaking the mixture in the mixed solvent at the temperature of 85 ℃ for 7 days, taking out, washing the mixture for 15 minutes, wiping off the surface moisture of the sample strip, and measuring the peeling strength between the intermediate metal layer and the thermal welding resin layer according to the method of initial peeling strength test.

(3) Water electrolyte resistance test of metal composite film finished product

The intermediate metal layer and the thermal welding resin composite layer of the metal composite film finished sample strip were peeled off by 20mm and then immersed in dimethyl carbonate (DMC) containing 1mol/L LiPF ₆: diethyl carbonate (DEC): the mass ratio of the Ethylene Carbonate (EC) material was 1:1:1, adding 1000PPM water accounting for the total mass of the electrolyte into the mixed solution, soaking for 7 days at the temperature of 85 ℃, taking out, washing with water for 15min, not wiping off water, and measuring the peeling strength between the intermediate metal layer and the thermal welding resin layer according to an initial peeling strength test method. The test method is to peel the metal layer and the heat-sealing resin layer in a state of residual moisture, and to measure the peel strength between the intermediate metal layer and the heat-sealing resin layer from a previously peeled part.

Examples 1-12 and comparative examples 1-2

As shown in fig. 3, the metal composite film 1000 provided in examples 1 to 12 and comparative examples 1 to 2 is composed of the outer base resin layer 16/the second adhesive layer 15/the second anticorrosive layer 14/the intermediate metal layer 13/the first anticorrosive layer 12/the first adhesive layer 11/the heat fusion resin layer 10.

The lamination method is as follows:

(1) An intermediate metal layer 13 was obtained, wherein the differences of the intermediate metal layer 13 in examples 1 to 12 and comparative examples 1 to 2 are shown in table 1:

Wherein the intermediate metal layers 13 of examples 1-12 and comparative examples 1-2 were each a nickel-plated stainless steel sheet having a total thickness of 45 μm, the specific differences were as follows:

In example 1, the surface dyne value of the intermediate metal layer 13 was 68 dyne/cm, and the thickness of the nickel plating layer on one side was 2. Mu.m.

Example 2 the water contact angle of the intermediate metal layer 13 was 10 deg., and the thickness of the nickel plating layer on one side was 2 μm.

The surface dyne value of the intermediate metal layer 13 of examples 3, 11 and comparative example 2 was 75dyn/cm, and the thickness of the nickel plating layer on one side was 2. Mu.m.

Examples 4 and 12 the water contact angle of the intermediate metal layer 13 was 15 °, and the thickness of the nickel plating layer on one side was 2 μm.

Example 5 the water contact angle of the intermediate metal layer 13 was 20 deg. and the thickness of the nickel plating layer on one side was 12 μm.

Example 6 the water contact angle of the intermediate metal layer 13 was 17 deg., and the thickness of the nickel plating layer on one side was 20 μm.

The water contact angle of the intermediate metal layer 13 of examples 7 and 8 and comparative example 1 was 2 °, and the thickness of the nickel plating layer on one side was 15 μm.

The surface dyne value of the intermediate metal layer 13 in examples 9 to 10 was 75dyn/cm, and the thickness of the nickel plating layer on one side was 0.2. Mu.m.

(2) The first corrosion preventing layer 12 and the second corrosion preventing layer 14 are formed on both surfaces of the intermediate metal foil, which is the intermediate metal foil, by performing corrosion preventing treatment with a corrosion preventing liquid in advance on both surfaces of the intermediate metal layer 13.

Wherein, in the embodiment 1, the anti-corrosion liquid comprises the following components in percentage by mass: 0.1% of polyacrylamide, 1.1% of phosphonocarboxylic acid copolymer, 1.2% of hydroxy acrylic resin, 1.9% of oxazoline compound, 2.0% of chromium fluoride, 0.3% of hydrofluoric acid, 1.2% of polyvinyl alcohol resin, 0.4% of zirconium fluoride and 91.8% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 2, the anticorrosive liquid comprises, in mass percent: 0.2% of polyacrylamide, 0.9% of phosphonocarboxylic acid copolymer, 0.8% of hydroxy acrylic resin, 2.1% of oxazoline compound, 3.5% of chromium nitrate, 5% of phosphoric acid, 2.5% of acrylic resin and 85% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 3, the anticorrosive liquid comprises, in mass percent: 0.5% of polyacrylamide, 0.2% of phosphonocarboxylic acid copolymer, 0.3% of hydroxy acrylic resin, 0.9% of oxazoline compound, 3.5% of chromium nitrate, 5% of phosphoric acid, 2.5% of acrylic resin and 87.1% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 4, the anticorrosive liquid comprises, in mass percent: 0.6% of polyacrylamide, 0.3% of phosphonocarboxylic acid copolymer, 0.4% of hydroxy acrylic resin, 1.3% of oxazoline compound, 2.0% of chromium fluoride, 0.3% of hydrofluoric acid, 1.2% of polyvinyl alcohol resin, 0.4% of zirconium fluoride and 93.5% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 5, the anticorrosive liquid comprises, in mass percent: 1.2% of polyacrylamide, 1.3% of phosphonocarboxylic acid copolymer, 0.6% of hydroxy acrylic resin, 2.4% of oxazoline compound, 2.0% of chromium fluoride, 0.3% of hydrofluoric acid, 1.2% of polyvinyl alcohol resin, 0.4% of zirconium fluoride and 90.6% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 6, the anticorrosive liquid comprises, in mass percent: 1.4% of polyacrylamide, 1.4% of phosphonocarboxylic acid copolymer, 0.8% of hydroxy acrylic resin, 2.8% of oxazoline compound, 2.0% of chromium fluoride, 0.3% of hydrofluoric acid, 1.2% of polyvinyl alcohol resin, 0.4% of zirconium fluoride and 89.7% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 7, the anticorrosive liquid comprises, in mass percent: 2.5% of polyacrylamide, 1.6% of phosphonocarboxylic acid copolymer, 1.4% of hydroxy acrylic resin, 3.8% of oxazoline compound, 2.0% of chromium fluoride, 0.3% of hydrofluoric acid, 1.2% of polyvinyl alcohol resin, 0.4% of zirconium fluoride and 86.8% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 8, the anticorrosive liquid comprises, in mass percent: 3% of polyacrylamide, 2% of phosphonocarboxylic acid copolymer, 2% of hydroxy acrylic resin, 4.9% of oxazoline compound, 2.5% of chromium nitrate, 4% of phosphoric acid, 2.5% of acrylic resin and 79.1% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 9, the anticorrosive liquid comprises, in mass percent: 2.2% of polyacrylamide, 1% of phosphonocarboxylic acid copolymer, 1.6% of hydroxy acrylic resin, 2.6% of oxazoline compound, 6% of chromium fluoride, 0.3% of hydrofluoric acid, 1.5% of polyvinyl alcohol resin and 84.8% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 10, the anticorrosive liquid comprises, in mass percent: 2.7% of polyacrylamide, 0.5% of hydroxy acrylic resin, 2.3% of oxazoline compound, 6% of chromium nitrate, 0.3% of phosphoric acid, 1.5% of acrylic resin and 86.7% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 11, the anticorrosive liquid comprises, in mass percent: 0.8% of polyacrylamide, 1.8% of phosphonocarboxylic acid copolymer, 3.7% of oxazoline compound, 1.9% of chromium nitrate, 4% of phosphoric acid, 2.5% of acrylic resin and 85.3% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In example 12, the anticorrosive liquid comprises, in mass percent: 1.9% of polyacrylamide, 0.7% of phosphonocarboxylic acid copolymer, 1.1% of hydroxy acrylic resin, 6% of chromium fluoride, 0.3% of hydrofluoric acid, 1.5% of polyvinyl alcohol resin and 88.5% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In comparative example 1, the anticorrosive liquid comprises, in mass percent: 1.2% of phosphonocarboxylic acid copolymer, 0.9% of hydroxy acrylic resin, 3% of oxazoline compound, 6% of chromium nitrate, 0.3% of phosphoric acid, 1.5% of acrylic resin and 87.1% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing.

In comparative example 2, the anticorrosive liquid comprises, in mass percent: 4.2% of polyacrylamide, 1.1% of phosphonocarboxylic acid copolymer, 0.7% of hydroxy acrylic resin, 3.2% of oxazoline compound, 2.0% of chromium fluoride, 4% of hydrofluoric acid, 2.5% of polyvinyl alcohol resin and 82.3% of solvent, wherein the solvent is water and ethylene glycol butyl ether according to 97:3, mixing. The main differences between the preservative agents used in examples 1 to 12 and comparative examples 1 to 2 are shown in Table 1. Wherein the anti-corrosion solutions used in examples 1 to 9 and comparative examples 1 to 2 were uniformly coated on both sides of the intermediate metal by coating rolls, the coating wet film amount of the anti-corrosion layer treatment solution was 5g/m ², and then heat-baked at 190℃for 2 minutes, to form the first anti-corrosion layer and the second anti-corrosion layer 14.

The anticorrosive solutions used in examples 10 to 12 were uniformly coated on both sides of the intermediate metal by coating rolls, the wet film coating amount of the anticorrosive layer treating solution was 5g/m ², and then heat-baked at 100℃for 2 minutes to form the first anticorrosive layer and the second anticorrosive layer 14.

(3) The film of the outer base resin layer 16 in contact with the second adhesive layer 15 is subjected to corona treatment.

A weight average molecular weight of 5000, tg of 50 ℃, a hydroxyl value of 25mg KOH/g, and a weight average molecular weight of 20000, tg of-17 ℃, a hydroxyl value of 8mg KOH/g, in a weight ratio of 3:2, toluene Diisocyanate (TDI) was added to form a second adhesive solution having an NCO/OH ratio of 6.2, the second adhesive solution was coated on the second anticorrosive layer 14 to form a second adhesive layer of 3 μm, the intermediate metal foil was thermally compounded with the second adhesive layer 15 and the outer base material resin layer 16 film, and then subjected to curing treatment at 80 ℃ for 3 days to form a semi-finished product of the outer base material resin layer 16/second adhesive layer 15 (3 μm)/second anticorrosive layer 14/intermediate metal layer 13.

(4) A first adhesive layer 11 and a heat-sealing resin layer 10 are laminated on the surface of a first anticorrosive layer 12 of the semi-finished product. The first adhesive layer 11 includes a hot-melt first adhesive layer B-1 and a solution first adhesive layer B-2, which are compounded in the following manner:

A. Hot melt type first adhesive layer B-1 compounding method: the hot melt resin used for the first adhesive layer 11 was anhydrous maleic anhydride-modified polypropylene, and a first adhesive layer having a thickness of 15 μm was formed on the surface of the first anticorrosive layer 12 of the intermediate metal layer 13 in contact with the hot melt resin layer 10, and further, was compounded with a hot melt resin having a thickness of 30 μm. The first adhesive layer 11 and the heat-sealing resin layer 10 are compounded on the first anticorrosive layer in contact with the heat-sealing resin layer 10 by melt coextrusion. The first adhesive layer 11 used was a mixture of 60% by weight of an anhydrous maleic anhydride-modified random copolymer polypropylene having a melting point of 140℃and an MFR (230 ℃) of 5g/10min, a degree of modification of the random copolymer polypropylene by the anhydrous maleic anhydride of 10%, 24% by weight of a copolymer elastomer of propylene and butene having a melting point of 160℃and an MFR (230 ℃) of 2.6g/10min and a density of 0.87g/cm ³, 8% by weight of a crystalline copolymer elastomer of ethylene and propylene having a melting point of 130℃and an MFR (230 ℃) of 9.5g/10min and a density of 0.91g/cm ³, and 8% by weight of a low density polyethylene having a melting point of 105℃and an MFR (230 ℃) of 12g/10 min.

The heat-fusible resin layer 10 is composed of two layers, and has the structure:

Resin layer a in contact with first adhesive layer 11: a blend layer of 62% by weight of a random copolymer polypropylene having a melting point of 155℃and an MFR (230 ℃) of 4g/10min, 33% by weight of a non-crystalline propylene-based elastomer and 5% by weight of a low density polyethylene having a melting point of 110℃and an MFR (230 ℃) of 7.5g/10 min;

The innermost resin layer B (the resin layer on the side facing away from the first adhesive layer 11): a layer consisting of a random copolymer polypropylene having a melting point of 155℃and an MFR (230 ℃) of 15g/10 min;

The thickness ratio of the resin layer a in contact with the first adhesive layer 11 to the innermost resin layer B was 8:2.

After the intermediate metal layer 13 was combined with the first adhesive layer 11 and the heat-fusible resin layer 10, heat treatment was performed at 180 ℃ for 2 seconds. Thus, a composite product of the outer base resin layer 16/the second adhesive layer 15 (3 μm)/the second anticorrosive layer 14/the intermediate metal layer 13/the first anticorrosive layer 12/the first adhesive layer 11 (15 μm)/the heat-fusible resin layer 10 (30 μm) was formed.

B. Solution type first adhesive layer B-2 compounding method: an anhydrous maleic anhydride-modified polypropylene solution having a weight average molecular weight of 80000, a melting point of 80℃and an acid value of 2mg KOH/g and an aromatic isocyanate (HDI system, hexamethylene diisocyanate) solution were mixed at a ratio of 20:1 to form a solid ratio, and then applying the solution-type mixture to the intermediate metal surface (i.e., the surface of the first anticorrosive layer 12) of the composite film having been subjected to anticorrosive treatment, which surface is in contact with the heat-sealing resin layer 10, of the composite film having been compounded with the outer base resin layer 16, drying the solution-type mixture to form a first adhesive layer B-2 having a thickness of 4 μm, then thermally compounding the adhesive layer B-2 with the adhesive surface of the 25 μm heat-sealing resin at a temperature of 80c, and further curing the resultant product at a temperature of 60c for 7 days, thereby forming a composite product of the outer base resin layer 16/second adhesive layer 15 (3 μm)/second anticorrosive layer 14/intermediate metal layer 13/first anticorrosive layer 12/first adhesive layer 11-2 (4 μm)/heat-sealing resin layer 10 (25 μm). The bonding surface of the 3 heat fusion resin layers 10 in contact with the first adhesive layer 11-2 was subjected to corona treatment in advance.

The three-layer structure of the heat welding resin is as follows:

resin layer in contact with the first adhesive layer 11: a layer composed of a random copolymer polypropylene having a melting point of 145℃and an MFR (230 ℃) of 7.5g/10 min;

Intermediate resin layer: a mixture layer of 40% by weight of a crystalline polymer elastomer composed of a block copolymer polypropylene having a melting point of 162℃and an MFR (230 ℃) of 2g/10min, 40% of a block copolymer polypropylene having a melting point of 160℃and an MFR (230 ℃) of 5g/10min, and 20% of an ethylene-propylene copolymer having a melting point of 130℃and an MFR (230 ℃) of 9.5g/10min, and a density of 0.91g/cm ³;

Innermost resin layer: a layer composed of a random copolymer polypropylene having a melting point of 145℃and an MFR (230 ℃) of 7.5g/10 min;

the three resin thickness ratios in the heat fusion resin layer 10 from one layer in contact with the first adhesive layer 11 to the innermost layer are sequentially 1:8:1.

The compounding modes corresponding to the examples and comparative examples are shown in Table 1.

The peel strength of the metal composite film finished product obtained above was measured, and the results are shown in table 1.

Table 1 examples 1-8 distinguish parameters and test results

Table 2 examples 9-12 differ from comparative examples 1-2 in parameters and test results

In tables 1 and 2, the retention rate means a ratio of the peel strength between the intermediate metal layer and the heat-seal resin layer measured after the presence/absence of the electrolyte solution to the initial peel strength. CAS number of hydroxy acrylic resin: 37956-57-3.

As can be seen from Table 1 and Table 2, the metal composite film provided by the application has a higher maintenance rate than that of comparative examples 1-2 in the anhydrous electrolyte resistance test, and meanwhile, the aqueous electrolyte resistance test examples 1-12 are both higher than that of comparative example 1, and examples 1-9 and 11-12 are both higher than that of comparative example 2, which indicates that the metal composite film provided by the application has excellent peel strength and excellent maintenance rate and long-acting property.

Wherein in examples 1 to 8, the initial peel strength of the metal composite film was 10.0N/15mm or more, and the peel strength maintenance rates after 14 days of standing in an electrolyte environment with no water and with water were 80% and 60% or more, respectively.

The number of carbon atoms (C) between carboxyl groups in the carbon chain of the carboxylic acid copolymer in the anticorrosive liquid of example 9 was 7. The initial peel strength between the intermediate metal layer and the heat-fusible resin layer in example 9 was 14.6N/15mm, and the maintenance rate in the electrolyte resistance test was: 67% without water and 48% with water showed low values compared to examples 1-8. Although the initial adhesion is sufficiently exhibited, the number of carbon atoms (C) at the carboxyl group interval in the preservative solution is 7, and the ability to deactivate the nitrogen atom (N) is low, which results in a low maintenance rate and poor long-term effect.

The content of the phosphonocarboxylic acid copolymer in the anticorrosive liquid for forming the anticorrosive layer in example 10 was 0%. The initial peel strength between the intermediate metal layer and the heat-fusible resin layer in example 10 was 14N/15mm, and the maintenance rate of the electrolyte resistance test was: 91% without water and 45% with water show low values compared to examples 1-8. Although the maintenance rate is high without adding water, the maintenance rate is low under the condition of adding water because the amino group fails for a long time due to the fact that the phosphonocarboxylic acid copolymer is not added in the preservative solution.

In example 11, a hydroxy acrylic resin was not added to the anticorrosive liquid for forming the anticorrosive layer. The initial peel strength between the intermediate metal layer and the heat-fusible resin layer in example 11 was 14.3N/15mm, and the maintenance rate in the electrolyte resistance test was: 88% without water and 54% with water showed low values compared to examples 1-8.

In example 12, a crosslinking agent was not added to the anticorrosive liquid for forming the anticorrosive layer. The initial peel strength between the intermediate metal layer and the heat-fusible resin layer in example 13 was 13.7N/15mm, and the maintenance rate in the electrolyte resistance test was: 75% in the absence of water and 48% in the presence of water give full play to the initial adhesion, but the first anticorrosive layer and the first adhesive layer are not crosslinked and cured due to the absence of a crosslinking agent, and thus cannot resist corrosion by hydrogen fluoride, and thus have poor long-term durability, and exhibit low values as compared with examples 1 to 8.

The anticorrosive liquid used in comparative example 1 was free of nitrogen-containing polymer, and therefore had a nitrogen atom (N) content of 1.0% at 100nm from the surface layer of the first anticorrosive layer toward the inside, at which time the first anticorrosive liquid could not react with the first adhesive layer, resulting in the maintenance rate of the electrolyte resistance test of the metal composite film of comparative example 1 under the condition that the initial peel strength was 14.4N/15 mm: 58% without water and 33% with water showed low values compared to examples 1-12.

The anticorrosive liquid used in comparative example 2 had a nitrogen-containing polymer content of 4.2% by mass, resulting in a nitrogen atom (N) content of 31% from the surface layer of the first anticorrosive layer toward the inside of 100 nm. At this time, the corrosion-resistant layer and the first adhesive layer react and solidify to an excessively high degree, so that the bonding layer becomes brittle and cracks are easy to generate. At this time, although the initial strength was as high as 15.3N/15mm, the maintenance rate in the electrolyte resistance test was: only 61% without water and 47% with water showed low values compared to examples 1-9 and 11-12, but superior to comparative example 1. Among them, it can also be seen from example 10 and comparative example 2 that the phosphonocarboxylic acid copolymer is advantageous for improving the retention of peel strength between the aqueous electrolyte resistance test-intermediate metal layer and the heat-seal resin layer.

According to the embodiments 1-12, it can be seen that, due to the addition of the nitrogen-containing polymer in the preservative solution, the preservative solution can be adapted to not only the hot-melt type first adhesive layer B-1 but also the solution type first adhesive layer B-2, thereby reducing the preparation cost of the metal composite film and improving the preparation efficiency.

In summary, according to the metal composite film provided by the application, the nitrogen-containing polymer is added into the preservative solution, and the content of nitrogen atoms in the first corrosion-resistant layer is controlled, so that the initial peel strength between the intermediate metal layer and the hot-melt resin layer of the obtained metal composite film is good, the metal composite film has good long-term effectiveness, the metal composite film can be matched with first adhesive layers of different types, the preparation cost of the metal composite film is reduced, the preparation efficiency is improved, and the promotion and the use of the metal composite film in the field of lithium ion batteries are facilitated.

The above is only a specific embodiment of the present application, and is not intended to limit the present application, but various modifications and variations can be made to the present application by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. The metal composite film is characterized by comprising a heat welding resin layer, a first adhesive layer, a first anti-corrosion layer, an intermediate metal layer and an outer base material resin layer which are sequentially overlapped;

Wherein the first adhesive layer comprises an acid-modified group and/or an isocyanate group, the first anti-corrosion layer comprises a nitrogen-containing polymer having an amine group reactive with the acid-modified group and/or the isocyanate group, and the content of nitrogen atoms in the first anti-corrosion layer is greater than 0 and equal to or less than 20at%.

2. The metal composite film according to claim 1, wherein the content of nitrogen atoms in the first anticorrosive layer is 1at% to 20at%.

3. The metal composite film according to claim 1, wherein the first anticorrosive layer is formed of an anticorrosive liquid by coating and heat treatment of the anticorrosive liquid;

wherein the mass percentage of the nitrogen-containing polymer in the anti-corrosion liquid is 0.1% -3%.

4. The metal composite film according to claim 3, wherein the corrosion protection liquid further comprises at least one of a carboxylic acid-containing polymer, a hydroxy acrylic resin and a crosslinking agent, wherein the mass percentage of the carboxylic acid-containing polymer in the corrosion protection liquid is 0.1 to 2.0%, the mass percentage of the hydroxy acrylic resin in the corrosion protection liquid is 0.1 to 2.0%, and the mass percentage of the crosslinking agent in the corrosion protection liquid is 0.5 to 5%.

5. The metal composite membrane of claim 4, wherein the carboxylic acid-containing polymer has a carbon chain with no more than 5 carbon atoms apart from the carboxyl groups.

6. The metal composite membrane of claim 4 wherein the carboxylic acid-containing polymer comprises a phosphonocarboxylic acid copolymer.

7. The metal composite film according to claim 4, wherein the crosslinking agent comprises at least one of an epoxy compound, an oxazoline compound, and an adipic acid dihydrazide compound.

8. The metal composite film according to claim 3, wherein the corrosion protection liquid further comprises a trivalent metal compound, an inorganic acid and an organic resin, wherein the trivalent metal compound is a trivalent chromium compound or a trivalent cerium compound, the trivalent metal compound accounts for 1.9-6% by mass of the corrosion protection liquid, the inorganic acid accounts for 0.3-6% by mass of the corrosion protection liquid, and the organic resin accounts for 0.6-6% by mass of the corrosion protection liquid;

The organic resin is composed of polyacrylic resin and/or polyvinyl alcohol, and the polyacrylic resin is one or more of polyacrylic acid, polymethyl acrylate, copolymer of acrylic acid and maleic acid, copolymer of acrylic acid and styrene and sodium salt and ammonium salt derivatives thereof.

9. The metal composite film according to claim 3, wherein the corrosion-preventing liquid contains a titanium compound or a zirconium compound, the titanium compound is 0 to 0.6% by mass in the corrosion-preventing liquid, and the zirconium compound is 0 to 2.8% by mass in the corrosion-preventing liquid.

10. The metal composite film according to any one of claims 1 to 9, wherein the first adhesive layer is made of a solvent type adhesive, the first adhesive layer containing isocyanate groups and/or acid modifying groups; or alternatively

The first adhesive layer is made of a hot melt adhesive, and the first adhesive layer contains an acid modifying group.

11. The metal composite film according to any one of claims 1 to 9, further comprising a second adhesive layer located between the outer substrate resin layer and the intermediate metal layer.

12. The metal composite film according to claim 11, further comprising a second corrosion protection layer located between the second adhesive layer and the intermediate metal layer.

13. The metal composite film according to claim 12, wherein the second corrosion protection layer comprises a nitrogen-containing polymer having amine groups, and the second adhesive layer comprises acid modifying groups and/or isocyanate groups that react with the amine groups.

14. The metal composite film according to claim 11, further comprising a coloring layer provided between the outer base material resin layer and the second adhesive layer, or provided on a side of the outer base material resin layer facing away from the intermediate metal layer.

15. The metal composite film according to claim 11, wherein the second adhesive layer contains a colorant.

16. The metal composite film according to any one of claims 1 to 9, wherein the thickness of the first corrosion protection layer is 1nm to 3.0 μm.

17. The metal composite film according to any one of claims 1 to 9, wherein the intermediate metal layer is a nickel-plated steel sheet.

18. An electrochemical device, characterized in that the metal composite film according to any one of claims 1 to 17 is used.