CN114156576A

CN114156576A - Outer packaging material for electrolyte-resistant lithium ion battery device and battery

Info

Publication number: CN114156576A
Application number: CN202111420546.9A
Authority: CN
Inventors: 庄志; 曹舒勇; 王小明; 虞少波; 冯宝平; 程跃
Original assignee: Jiangsu Ruijie New Material Technology Co ltd
Current assignee: Jiangsu Ruijie New Material Technology Co ltd
Priority date: 2021-11-26
Filing date: 2021-11-26
Publication date: 2022-03-08
Also published as: WO2023093072A1

Abstract

The invention relates to the technical field of production of packaging materials for lithium ion batteries, in particular to a packaging material for a lithium ion battery and a battery, wherein an inner heat fusion layer and an intermediate metal layer are provided with an adhesive layer with upward electrolyte peeling strength.

Description

Outer packaging material for electrolyte-resistant lithium ion battery device and battery

Technical Field

The invention relates to the technical field of aluminum plastic film production, in particular to an electrolyte-resistant outer packaging material for a lithium ion battery device.

Background

At present, lithium ion batteries are mainly divided into three types, namely square, cylindrical and soft packaged, wherein the square and cylindrical shells mainly adopt hard shells made of aluminum alloy, stainless steel and the like, the aluminum alloy shells can be made of pure aluminum, and the soft packaged shells adopt aluminum plastic films, so that the problem of inflexible appearance design of hard packaged batteries is greatly improved.

The aluminum-plastic film comprises an outer base material resin layer, an outer adhesive layer, a middle metal layer, an inner adhesive layer and an inner heat welding layer in sequence from outside to inside. As a battery outer packaging material, the aluminum plastic film is required to have electrolyte corrosion resistance, so that the problems of leakage and the like of a battery pack can be prevented, and the service life of the battery is ensured.

Generally, an internal heat fusion layer and an intermediate metal layer in an outer packaging material for a lithium ion battery device are bonded together through an internal adhesive layer, so that the internal heat fusion layer and the intermediate metal layer are prevented from being layered, the contact between electrolyte and the intermediate metal layer is reduced, and the service life and the safety of the lithium ion battery device are improved. Therefore, the adhesive in the outer packaging material of the lithium ion battery device has great influence on the service life and the safety of the lithium ion battery device.

At present, an inner adhesive layer of an outer packaging material of a lithium ion battery is a solvent type adhesive mainly composed of acid modified polypropylene and an epoxy resin curing agent. In addition, as another method, a hot-melt type acid-modified polypropylene resin may be used as the inner adhesive layer. The metal composite film compounded by the inner adhesive layers has better maintenance of the adhesive strength under the condition of common electrolyte. However, the electrolyte solution which is left for a long time absorbs a part of moisture in the environment, the moisture dissolved in the electrolyte solution reacts with the electrolyte to generate acid substances with strong corrosiveness, the inner adhesive layer is corroded, the electrolyte solution is dissolved in the inner adhesive layer to expand after being stored for a long time, and the bonding strength between the intermediate metal layer and the inner heat fusion layer is reduced. Therefore, the aluminum-plastic film is easy to generate interlayer separation, electrolyte has leakage danger, serious loss caused by thermal runaway of the battery can be caused, and popularization and application of the aluminum-plastic film in the field of lithium ion batteries are further influenced.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide an outer packaging material for a lithium ion battery device, which has stronger electrolyte corrosion resistance.

In order to achieve the purpose, the technical scheme of the invention is realized as follows:

the invention aims to provide an outer packaging material for an electrolyte-resistant lithium ion battery device, which comprises an outer base material resin layer, an intermediate metal layer, an inner adhesive layer and an inner heat-sealing layer; the inner adhesive layer is formed by an adhesive containing acid modified polypropylene resin and a curing agent; the acid modified polypropylene resin is at least one of block copolymerization polypropylene, random copolymerization polypropylene and homopolymerization polypropylene, wherein the content of crystalline polypropylene is more than 50%.

Further, the acid modifier used for the acid-modified polypropylene resin includes acrylic acid, methacrylic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, succinic acid, etc., half ester, half amide of unsaturated dicarboxylic acid, etc. Among them, acrylic acid, methacrylic acid, maleic anhydride and succinic acid are preferable, and maleic anhydride and succinic acid are more preferable. The acid component may be copolymerized with the polyolefin resin, and the form thereof is not limited, and examples of the copolymerized state include random copolymerization, block copolymerization, graft copolymerization (graft modification), copolymerization by a thermal subtractive method, and the like.

Further, the melting point of the acid modified polypropylene resin is between 60 and 97 ℃, and the weight average molecular weight is between 6000 and 80000.

Further, the acid-modified polypropylene resin has a melting point of 75 to 90 ℃.

Further, the inner layer adhesive acid value used in the inner adhesive layer is 0.5-5 mgKOH/g.

Further, the inner layer adhesive layer uses an inner layer adhesive acid value of 1 to 3 mgKOH/g.

The curing agent is at least one of a resin containing an isocyanate component, an epoxy resin, a methanesulfonic acid resin and an amine compound.

Further, when the curing agent is a resin containing an isocyanate component, it is a mixture containing 50% or more of an isocyanate derivative of pentamethylene diisocyanate, or an isocyanate mixture of an isocyanate derivative of pentamethylene diisocyanate and an allophanate of pentamethylene diisocyanate. Wherein the functionality degree of the pentamethylene diisocyanate is between 3.0 and 4.5.

Here, hydrogen bonds are generated between the isocyanate group (-NCO) and the urethane group (-NHCOO-) and the material containing active hydrogen, so that the intramolecular force is enhanced and the adhesive strength is increased.

Further, at least one surface of the middle metal layer, which is in contact with the inner adhesive layer, is treated by a preservative solution; the corrosion-resistant liquid comprises, by mass, 19-60 parts of a trivalent chromium compound, 3-60 parts of an inorganic acid, 6-60 parts of an organic resin and 0-10 parts of a fluoride; the trivalent chromium compound at least comprises one of chromium nitrate, chromium phosphate and chromium chloride.

Here, the trivalent chromium compound can form a coordination crosslinking structure centered on a Cr atom on the metal surface, and functions to increase the crosslinking degree of the anticorrosive film on the metal surface.

Furthermore, the above-mentioned mass parts are expressed only in a certain formulation range of an embodiment, and the actual mass can be multiplied by several times according to the production amount, so that the key point is to define the proportional relationship among the components in the preservative solution, i.e. the ratio of the trivalent chromium compound, the inorganic acid, the organic resin and the fluoride should satisfy (19-60): 3-60): 6-60): 0-10.

Here, when the ratio of the trivalent chromium compound exceeds the above range, the anticorrosive film on the metal surface is hardened, the folding resistance of the corresponding metal composite film is deteriorated, if bending or forming is performed, the anticorrosive layer is cracked, the entering of the electrolyte causes the reduction of the insulation property, and the hydrogen fluoride corrosion causes the peeling of the intermediate metal layer and the inner heat fusion layer, resulting in the occurrence of electrolyte leakage; when the proportion of the trivalent chromium compound is less than the above range, the crosslinking degree of the anticorrosive film on the metal surface is low, and the anticorrosive effect cannot be achieved.

When the ratio of the inorganic acid is less than the above range, the oxide film on the metal surface cannot be removed cleanly, the adhesion between the corrosion-preventing layer and the intermediate metal layer is deteriorated, and the intermediate metal layer and the inner heat fusion bonded layer may be peeled off during long-term storage of the device.

Here, when the proportion of the organic resin is less than the above range, the anticorrosive film on the metal surface is delaminated and easily broken, and the corrosion resistance of the corresponding metal composite film is deteriorated; when the proportion of the organic resin exceeds the above range, the metal surface anticorrosive film is too thick, is easy to crack, is easy to absorb water, and is easy to generate hydrofluoric acid in an electrolyte environment to corrode the metal surface, so that the corrosion resistance of the corresponding metal composite film is deteriorated.

Preferably, the ratio of the trivalent chromium compound, the inorganic acid, the organic resin and the fluoride is (19-60): (3-60): 6-60): 1-10.

Here, when the proportion of the fluoride exceeds the above range, the bridging property of trivalent chromium may be deteriorated to affect the generation of the corrosion prevention layer, the intermediate metal layer and the internal heat fusion layer may be peeled off, and the resource may be wasted; when the proportion of the fluoride is less than the above range, the effect of corrosion resistance against hydrofluoric acid is not good, and the corrosion prevention effect of protecting the metal surface is not exerted.

Further, the inorganic acid is at least one of nitric acid and phosphoric acid; the fluoride is at least one of chromium fluoride and aluminum fluoride; the organic resin is composed of polyacrylic resin and polyvinyl alcohol; the polyacrylic resin is one or more of polyacrylic acid, polymethyl acrylate, a copolymer of acrylic acid and maleic acid, a copolymer of acrylic acid and styrene, and sodium salt and ammonium salt derivatives thereof.

Here, the inorganic acid functions to remove an oxide film on the metal surface.

Here, the polyacrylic acid resin functions to improve the film formability of the corrosion-resistant layer on the metal surface.

Here, the fluoride plays a role of increasing resistance of the metal film to hydrofluoric acid.

The weight average molecular weight of the polyacrylic resin is preferably about 1000 to 100 ten thousand, more preferably about 3000 to 80 ten thousand, and further preferably about 1 ten thousand to 80 ten thousand.

Here, the larger the weight average molecular weight of the polyacrylic resin, the higher the durability thereof, but the water solubility of the polyacrylic resin is lowered, the coating liquid becomes unstable, and the production stability is affected. Conversely, the smaller the weight average molecular weight of the polyacrylic resin, the lower the durability thereof. When the weight average molecular weight of the polyacrylic acid resin is 1000 or more, the durability is high; when the weight average molecular weight is 100 ten thousand or less, the coating stability in production is good.

Further, the outer packaging material for the electrolyte-resistant lithium ion battery device also comprises an outer adhesive layer arranged between the outer base material resin layer and the middle metal layer; the outer adhesive used in the outer adhesive layer is two-component or multi-component polyester polyol and isocyanate solvent; the thickness of the outer adhesive layer is 2-5 μm.

Still further, a colored layer is further included, the colored layer being set between the outer base resin layer and the outer adhesive layer or the colored layer being formed by adding a pigment to the outer adhesive layer.

Furthermore, an outer anti-corrosion layer is arranged on one side of the middle metal layer, which is in contact with the outer adhesive layer.

Further, the outer packaging material for an electrolyte solution-resistant lithium ion battery device further includes a coloring layer provided on the outer side of the outer base resin layer.

Further, the outer packaging material for the electrolyte-resistant lithium ion battery device further comprises an outer anti-corrosion layer arranged on one side of the middle metal layer, which is in contact with the outer base material resin layer.

It is another object of the present invention to provide a battery using any of the above electrolyte-resistant lithium ion battery pack outer materials.

Drawings

Fig. 1 a schematic structural diagram of the present application:

the labels in the figures are:

1 is an outer substrate resin layer;

2 is an outer adhesive layer;

3 is a coloring layer;

4 is a corrosion-resistant layer;

5 is an intermediate metal layer;

6 is a corrosion-resistant layer;

7 is an inner layer adhesive layer;

8 is a thermal welding resin layer;

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

Outer substrate resin layer:

in the present invention, the outer base resin layer is provided to exhibit a base function as a packaging material for a lithium ion battery. The outer base resin layer is positioned on the outer layer side of the packaging material for the lithium ion battery.

The material for forming the outer base resin layer is not particularly limited as long as it has at least an insulating property as a function of the base. For example, the resin may be used, and an auxiliary may be added to the resin.

There are various methods for preparing the outer substrate resin layer. For example, a resin film product may be formed directly from a resin, or a coated resin product may be formed. The resin film may be an unstretched film or an stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film, and a biaxially stretched film is preferable. As a method for producing the biaxially stretched film, for example, a stepwise biaxial stretching method, a blown film method, a simultaneous stretching method are exemplified. Examples of the resin coating method include a roll coating method, a gravure coating method, and an extrusion coating method.

Examples of the resin forming the outer base resin layer include resins such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified products of these resins. The resin forming the outer base resin layer may be a copolymer of these resins, a modified product of the copolymer, or a mixture of these resins.

As the resin forming the outer base resin layer, polyester and polyamide are preferably listed.

Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, and copolyester. Examples of the copolyester include a copolyester mainly composed of ethylene terephthalate as a repeating unit. Specifically, a copolymer polyester obtained by polymerizing ethylene terephthalate as a main repeating unit and ethylene isophthalate (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. These polyesters may be used alone in 1 kind, or 2 or more kinds may be used in combination.

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; a hexamethylenediamine-isophthalic acid-terephthalic acid copolymer polyamide such as nylon 6I, nylon 6T, nylon 6IT, and nylon 6I6T (I represents isophthalic acid, and T represents terephthalic acid) containing a terephthalic acid-and/or isophthalic acid-derived structural unit, and an aromatic polyamide such as polyamide MXD6 (polyamide PACM6 (poly-bis (4-aminocyclohexyl) methane azide), and these polyamides may be used in 1 kind alone or in combination of 2 or more kinds.

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

The outer base resin layer may be a single layer or may be composed of 2 or more layers. When the outer base resin layer is composed of 2 or more layers, the outer base resin layer may be a composite film formed by the action of an adhesive, or may be a resin composite film formed by co-extruding resins into 2 or more layers. The resin composite film formed by coextruding the resins into 2 or more layers may be used as the outer base resin layer in an unstretched state, or may be uniaxially or biaxially stretched to be used as the outer base resin layer.

Specific examples of the laminate of 2 or more resin films in the outer base resin layer include a composite film of a polyester film and a nylon film, a 2 or more nylon composite film, and a 2 or more polyester composite film. Preferred are a laminate of a stretched nylon film and a stretched polyester film, a stretched nylon composite film having 2 or more layers, and a stretched polyester composite film having 2 or more layers. For example, when the outer base resin layer is a 2-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 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 is more preferable. In addition, since the polyester resin is less likely to be discolored when the electrolyte solution adheres to the surface, when the outer base resin layer is a resin composite film having two or more layers, the polyester resin film is preferably located on the outermost layer of the outer base resin layer.

When the outer base resin layer is a resin composite film having two or more layers, the two or more layers may be combined with an adhesive. As a preferable adhesive, a glue solution having the same composition as the outer layer adhesive can be used. The method for laminating two or more resin films is not particularly limited, and a dry lamination method, a sandwich lamination method, an extrusion lamination method, a thermal lamination method, or the like can be used, and a dry lamination method is preferred. When the composite is carried out by a dry-type composite method, a polyurethane adhesive is preferably used as the adhesive for the outer layer. At this time, the thickness of the adhesive layer may be about 2-5 μm.

Further, one or more additives such as a lubricant, a flame retardant, an anti-blocking agent, an antioxidant, a light stabilizer, a tackifier, and an antistatic agent may be added to the surface and the inside of the outer base resin layer.

From the viewpoint of improving the moldability of the packaging material for lithium ion batteries, it is preferable to form a lubricant on the surface of the outer base resin layer. The lubricant is not particularly limited, but an amide-based lubricant is preferable. The amide-based lubricant includes saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid amides, aromatic bisamides, 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, for example. Examples of the unsaturated fatty acid amide include oleamide and erucamide. Substituted amides include N-oil palmitamide, N-stearamide, N-oil stearamide, and N-stearamide. In addition, the methylolamide includes methylolstearic acid amide and the like. The saturated fatty acid bisamide includes methylenebisstearamide, ethylenebisoctanoamide, ethylenebislaurate amide, ethylenebisstearamide, ethylenebishydroxystearamide, ethylenebisbehenamide and hexamethylenebisstearamide, n '-distearyladipamide, n' -distearylsebacate amide and the like. Unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucamide, hexamethylene bisoleic acid amide, n '-dioleyl adipic acid amide, and n, n' -dioleyl sebacic acid amide. 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 in 1 kind, or two or more kinds may be used in combination.

When the lubricant is present on the surface of the outer base resin layer, the amount of coating is not particularly limited, but about 3mg/m is preferably applied²Above, more preferably 4 to 30mg/m²Left and right.

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

The thickness of the outer base resin layer is not particularly limited as long as it functions as a base. Preferably about 3 to 50 μm, more preferably about 10 to 35 μm. When the outer base resin layer is a resin composite film having 2 or more layers, the thickness of the resin film constituting each layer is preferably about 2 to 30 μm.

Outer adhesive layer:

in the packaging material for a lithium ion battery of the present invention, the outer-layer adhesive layer is provided in the case where the outer base resin layer and the intermediate metal layer are combined. The outer adhesive layer is a layer formed for the purpose of improving adhesion between the outer base resin layer and the intermediate metal layer, and the like.

The outer adhesive layer is formed of an adhesive capable of bonding the outer base resin layer and the intermediate metal layer. The adhesive used for forming the outer adhesive layer is not limited, and may be, for example, a two-pack curing adhesive (two-pack adhesive) or a one-pack curing adhesive (one-pack adhesive). The adhesive used for forming the outer adhesive layer may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot press type, and the like. The outer adhesive layer may be a single layer or a plurality of layers.

The outer adhesive layer is a two-component polyurethane adhesive formed by using polyester polyol, polyurethane modified polyol and the like as main diol agents and using 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 a polyfunctional epoxy resin, a methanesulfonic acid-containing polymer, a porlyamine resin, an inorganic acid, and the like. Examples of the main agent for the outer adhesive layer include polyester resins 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 resins; a polyimide resin; a polycarbonate; amino resins such as urea resins and melamine resins; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; silicone resins, and the like. These adhesive components can be used alone in 1, or can be used in combination of 2 or more.

The combination of the outer adhesive layer more preferred in the present invention is one or two of binary or polybasic polyester, polyurethane modified polyester and isocyanate. The isocyanate is not particularly specified in the compounds having two or more isocyanate groups in the molecule. For example, one or a mixture of two or more of polymers such as isophorone diisocyanate (IPDI), Toluene Diisocyanate (TDI), diphenylmethane-4, 4' -diisocyanate (MDI), and 1, 6-hexamethylene diisocyanate.

The outer layer adhesive layer may contain a colorant, a thermoplastic elastomer, a tackifier, a filler, and the like, as long as the addition of other components is not inhibited. The outer adhesive layer contains a coloring agent, whereby the packaging material for lithium ion batteries can be colored. As the colorant, a colorant such as a pigment or a dye can be used. Further, 1 kind of the colorant may be used, or two or more kinds may be mixed and used.

The type of the pigment is not particularly limited as long as the adhesiveness of the outer layer adhesive layer is not impaired. Examples of the organic pigments 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-based, titanium oxide-based, cadmium-based, lead-based, isoindoline-based pigments and the like can be used. 7. Among the coloring agents, carbon black is preferable, for example, in order to make the appearance of the packaging material for lithium ion batteries black.

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

The content of the pigment in the outer adhesive layer 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 outer adhesive layer is not particularly limited as long as the outer base resin layer and the intermediate metal layer can be bonded to each other, and the lower limit thereof is, for example, about 1 μm or more or about 2 μm or more, and the upper limit thereof is, for example, about 10 μm or less or about 5 μm or less, and a preferable range thereof is about 1 to 10 μm, and more preferably about 1 to 5 μm.

Coloring layer:

the colored layer is a layer provided between the outer base resin layer and the intermediate metal layer as necessary. In the case of having an outer adhesive layer, it may be between the outer base resin layer and the outer adhesive layer. Further, the colored layer may be provided outside the outer base resin layer. By providing the coloring layer, the packaging material for a lithium ion battery can be colored.

The colored layer can be formed by, for example, applying ink containing a colorant to the surface of the outer base resin layer 1, the surface of the outer adhesive layer a, or the surface of the intermediate metal layer. As the colorant, a colorant such as a pigment or a dye can be used. The colorant may be used alone in 1 kind, or may be used in combination of 2 or more than 2 kinds.

As a specific example of the coloring agent contained in the colored layer, the example described with reference to the outer adhesive layer can be cited.

Intermediate metal layer:

in the exterior material for a lithium ion battery, the intermediate metal layer is a barrier layer capable of suppressing at least moisture penetration.

The metal material used for the intermediate metal layer may be specifically an aluminum alloy, stainless steel, titanium steel, nickel-plated iron plate, or the like, and when used as a metal foil, it may be one or more layers. Preferably, the steel sheet contains at least one of aluminum alloy foil, nickel-plated iron plate, and stainless steel foil.

In general, the aluminum alloy foil is selected as follows, and from the viewpoint of improving formability of the packaging material for lithium ion batteries, a soft aluminum alloy foil made of an annealed aluminum alloy or the like is more preferably used as the aluminum alloy foil, and from the viewpoint of further improving formability, an iron-containing aluminum alloy foil is preferably used as the aluminum alloy foil. Silica, magnesium, or the like may be added as needed for electrolyte resistance and the like.

Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardening stainless steel foils. The stainless steel foil is preferably made of austenitic stainless steel from the viewpoint of providing a packaging material for lithium ion batteries having more excellent formability.

Specific examples of austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, and SUS316L, and among them, SUS304 is particularly preferable.

When the intermediate metal layer is a metal foil, the thickness is such that the intermediate metal layer can function as an intermediate metal layer that suppresses penetration of water, and is, for example, about 9 to 200 μm. The upper limit of the thickness of the intermediate metal layer 3 is preferably about 100 μm or less, and more preferably about 50 μm or less.

In addition, the volatility of the rolling oil is influenced by alloy components deposited on the surface of the metal layer in the middle-smelting house after the alloy components are added or an annealing process performed after the rolling process. Therefore, in adjusting the alloy composition, it is important to control the surface cleanliness. The cleanliness of a surface can be managed by a method using a wetting agent test for wettability or a method using a contact angle as an index. The index of wettability is D class or more, preferably B class. In addition, as an index of the contact angle, 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 or the contact angle exceeds 25 degrees, the reactivity with an anticorrosive layer described later or the initial adhesion is deteriorated. If the reactivity deteriorates and the reaction between the anticorrosive layer and the intermediate metal layer becomes insufficient, the resistance to permeation of the electrolyte as the battery content and the resistance to hydrogen fluoride generated in the reaction of the electrolyte and water decrease. As time passes, the adhesion of the anticorrosive layer to the intermediate metal layer is reduced, the anticorrosive layer is dissolved, and the intermediate metal layer and the anticorrosive layer may be peeled off, thereby shortening the life of the battery. The same situation occurs when the initial adhesion between the anticorrosive layer and the intermediate metal layer is deteriorated. The invention can inhibit the alloy from being separated out from the metal layer in the middle through the adjustment of the alloy components and the adjustment of the alloy ratio in a certain range. In addition, in the annealing step during rolling, the temperature and time conditions can be easily controlled.

The method for testing the surface wettability of metal layers in Zhongyuan can employ "national Standard of the people's republic of China GB/T225638.5-2016, method of the aluminum foil test, part 5: detection of wettability ". The contact angle test method of the metal layer in Zhongyuan can adopt the methods of "national standard of the people's republic of China GB/T22638.9-2008, part 9 of the aluminum foil test method: determination of hydrophilicity "

And (3) an anticorrosive layer:

the anti-corrosion layer is used in the packing material of lithium ion battery to avoid hydrogen fluoride generated by the reaction of electrolyte and water to corrode the surface of the intermediate metal layer, prevent the intermediate metal layer and the internal heat welding resin layer from separating, and maintain the surface homogeneity of the intermediate metal layer, so that the change of the adhesion (wettability) is small, and the anti-corrosion layer has the effect of preventing the intermediate metal layer and the internal heat welding resin layer in the metal composite film from delaminating. Preferably, the corrosion-preventing layer is formed by applying the corrosion-preventing liquid to at least the surface of the intermediate metal layer opposite to the outer base resin side, and preferably, the corrosion-preventing layer is formed on both sides of the intermediate metal layer. The anti-corrosion layer is formed on the surface of the intermediate metal layer in contact with the outer base resin layer, so that the surface uniformity of the intermediate metal layer is stable, the change of the cohesiveness (wettability) is reduced, the composite film is stored for a long time in a high-temperature and high-humidity environment, and the anti-delamination effect is achieved between the outer base resin layer and the intermediate metal layer of the metal composite film.

As an anticorrosion layer formed by chemical conversion treatment, various anticorrosion liquids mainly containing phosphates, nitric acid, chromates, fluorides, rare earth oxides, and the like have been known.

Chemical conversion treatments using phosphates and chromates include, for example, chromium chromate treatment, chromium phosphate treatment, phosphoric acid-chromate treatment, and the like, and examples of chromium compounds used in these treatments include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium diphosphonate, chromium acetate, chromium chloride, and chromium sulfate. The chromate treatment method mainly includes etching chromate treatment, electrolytic chromate treatment, coating chromate treatment, and the like, but coating chromate treatment is preferable. In the coating chromate treatment, a treatment liquid containing a metal phosphate such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, Zn (lead metalloid) phosphate, or a mixture of these metal salts as a main component, or a treatment liquid containing a mixture of a nonmetal phosphate and these nonmetal salts as a main component is mixed with a synthetic resin and then applied to the degreased surface by a known coating method such as a roll coating method, a gravure printing method, or an immersion method, followed by drying. Various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester compound solvents, and ether solvents can be used as the treatment liquid, but water is preferred. As the resin component used in the present invention, a water-soluble polymer such as an aminated phenol or a polyacrylic acid-based resin can be selected.

An example of the corrosion-preventing layer is formed by applying a particulate material in which a metal oxide such as alumina, titanium oxide, cerium oxide, or tin oxide and precipitated barium sulfate are dispersed in phosphoric acid to the surface of the intermediate metal layer and then performing a sintering treatment at 150 ℃.

Other examples of the corrosion-preventing layer mainly include a thin film obtained by a coating-type corrosion-preventing treatment containing at least one component selected from the group consisting of an oxide sol of a rare earth element, an anionic polymer, and a cationic polymer. The coating agent may contain phosphoric acid, phosphate, or a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of a rare earth element oxide (for example, particles having an average particle diameter of 100nm or less) are dispersed in a liquid dispersion medium. The rare earth element oxide mainly contains cerium oxide, yttrium oxide, neodymium oxide, lanthanum oxide, and the like, and cerium oxide is preferable from the viewpoint of further improving the adhesion. The rare earth element oxide contained in the corrosion prevention layer may be used alone or in combination of two or more. As the liquid dispersion medium of the rare earth element oxide sol, various solvents such as water, an alcohol-based solvent, a hydrocarbon-based solvent, a ketone-based solvent, an ester-based solvent, and an ether-based solvent can be used, and water is preferred. The cationic polymer mainly includes polyethylene pipe imine, a complex ion polymer complex formed by a polymer containing polyethylene pipe imine and carboxylic acid, a primary amine grav-torr acrylic resin obtained by graft copolymerization of primary amine on an acrylic main chain, polyacetic acid or its derivative, aminated phenol, and the like. Further, as the anionic polymer, a copolymer mainly containing poly (meth) acrylic acid or a salt thereof, or (meth) acrylic acid or a salt thereof is preferable. The crosslinking agent is preferably at least 1 of a compound having any one of an isocyanate chemical group, a glycidyl chemical group, a carboxyl chemical group, and an oxazoline chemical group, and a silane coupling agent.

The anticorrosive layer mainly comprises a trivalent chromium compound, an inorganic acid, fluoride, organic resin and water, and the proportion of the trivalent chromium compound, the inorganic acid, the fluoride and the organic resin in the anticorrosive layer coated on the intermediate metal layer is controlled to be (19-60): (3-60): (0-10): (6-60). Wherein the ratio of the trivalent chromium compound to the organic resin is in the range of (3-100): 10;

the trivalent chromium compound in the preservative solution at least comprises one of chromium nitrate, chromium phosphate, chromium fluoride and chromium chloride; the inorganic acid is at least one of nitric acid and phosphoric acid; the fluoride is composed of chromium fluoride; the organic resin is composed of polyacrylic resin and polyvinyl alcohol; 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, ammonium salt and other derivatives thereof, and has a weight average molecular weight of 10000-800000.

The anti-corrosion layer is an aqueous solution mainly composed of a trivalent chromium compound, an inorganic acid, an organic resin, an organic solvent and titanate, and the proportion of the trivalent chromium compound, the inorganic acid, the organic resin and the titanate in the anti-corrosion layer formed on the intermediate metal layer is controlled to be (25-38): (1-8): (10-12): (0-5). Wherein, the proportion of the trivalent chromium compound to the organic resin is controlled to be (2-4): 1, in the above range.

The trivalent chromium compound in the anti-corrosion liquid at least comprises one of chromium nitrate, chromium fluoride, chromium chloride and chromium phosphate, the inorganic acid at least comprises one of nitric acid and hydrofluoric acid, and the organic resin is polyvinyl alcohol.

The anticorrosive layer of the present invention is mainly composed of a resin containing an aminophenol polymer, a trivalent chromium compound and a phosphorus compound, and the ratio of the aminophenol polymer, the trivalent chromium compound and the phosphorus compound in the anticorrosive layer coated on the aluminum alloy foil layer is about 1 to 200mg per m2 parts of the aminophenol polymer of the resin film layer, and preferably, the ratio is controlled within a range of about 0.5 to 50mg in terms of chromium of the trivalent chromium compound and about 0.5 to 50mg in terms of phosphorus of the phosphorus compound. The aminated phenol multimer, trivalent chromium compound and phosphorus compound can use the compounds shown above.

The corrosion prevention layer of the present invention is mainly composed of at least 2 layers of a 1 st layer composed of cerium oxide, phosphoric acid or phosphate formed on the aluminum foil side and a layer composed of a cationic or anionic polymer formed on the inner layer adhesive layer side. In the layer 1, phosphoric acid or a phosphate is preferably used in an amount of 1 to 100 parts by mass based on 100 parts by mass of the acid value cerium. The phosphate, cationic polymer, or anionic polymer may be those described above.

Examples of the fluoride include hydrofluoric acid, chromium fluoride, magnesium fluoride, an iron fluoride element, cobalt fluoride, nickel fluoride, ammonium fluoride, titanium fluoride and a complex thereof, a zirconium fluoride salt or a complex thereof, magnesium fluoride, and ammonium hydrogen fluoride. In the present invention, chromium fluoride is preferred.

In the present invention, the titanate is not particularly limited, and may be selected from one or more of titanous sulfate, titanium oxysulfate, titanium ammonium sulfate, titanium nitrate, titanium ammonium nitrate, titanium sulfate, fluorotitanic acid and a complex thereof, ethyl acetoacetate, trimethylethanol, melamine, and n-butylhydroquinone.

The polyacrylic resin is preferably polyacrylic acid, an acrylic acid methacrylate copolymer, an acrylic acid maleic acid copolymer, a styrene acetate copolymer, or a derivative thereof such as a sodium salt, an ammonium salt, or an amine salt. Particularly preferred are polyacrylic acid derivatives such as ammonium salts, sodium salts, and amine salts of polyacrylic acid. Polyacrylic acid here means a polymer of acrylic acid. The polyacrylic resin is preferably a copolymer of acrylic acid and dicarboxylic acid or dicarboxylic anhydride, and is preferably an ammonium salt, sodium salt or amine salt of a copolymer of acrylic acid and carboxylic acid or dicarboxylic anhydride. The polyacrylic resin may be used alone, or two or more kinds may be used in combination.

The weight average molecular weight of the polypropylene resin is preferably about 1000 to 100 ten thousand, more preferably about 3000 to 80 ten thousand, and the higher the molecular weight is, the higher the corrosion resistance is, but the water solubility of the polyacrylic resin is low, the unstable corrosion-resistant solution to be formulated is, and the production stability is poor. Further, the smaller the molecular weight, the lower the corrosion resistance. In the present invention, the polyacrylic resin has a weight average molecular weight of 1000 or more, and has high durability, and good production stability when 100 ten thousand or less.

As the formation of the corrosion prevention layer, at least the internal thermal adhesive resin layer of the intermediate metal layer is degreased by a treatment method such as an alkali immersion method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an oxygen activation method, or a heat treatment (annealing treatment) for calendering. Then, the anti-corrosion liquid of the invention is used to perform coating by a bar coating method, a roll coating method, a gravure coating method, a dipping method and the like, and high-temperature chemical combination reaction is performed on the surface of the intermediate metal layer, and the intermediate metal layer coated with the anti-corrosion liquid is subjected to heat treatment at the high temperature of 130-.

The thickness of the corrosion-preventing layer is not particularly limited, but is preferably 1nm to 3.0. mu.m, more preferably 1nm to 1.5. mu.m, from the viewpoint of the adhesion force between the intermediate metal layer and the hot-melt resin layer. In addition, the amount of the chromium in the anti-corrosion layer ranges from 8mg per square meter to 50mg per square meter, preferably from 10mg per square meter to 30mg per square meter.

Inner adhesive layer:

in the packaging material for a lithium ion battery of the present invention, the inner adhesive layer is an intermediate layer provided to firmly bond the intermediate metal layer and the inner heat-fusible layer.

The inner adhesive layer is formed of a resin capable of bonding the intermediate metal layer and the inner heat-fusible layer. As a resin for forming the inner adhesive layer. The internal heat-sealing resin layer may be a polyolefin, a cyclic polyolefin, or a modified polyolefin resin such as a carboxylic acid-modified polyolefin, a carboxylic acid-modified cyclic polyolefin, a methacrylic acid-modified polyolefin, an acrylic acid-modified polyolefin, a crotonic acid-modified polyolefin, or an imide-modified polyolefin. From the viewpoint of improving the adhesion between the intermediate metal layer and the inner heat fusion layer, the modified polyolefin is preferably a modified polyolefin resin such as acrylic acid, methacrylic acid, maleic acid, anhydrous maleic anhydride, or polyamide. The resin constituting the inner adhesive layer may or may not contain a polyolefin backbone, preferably a polyolefin backbone. Whether or not the resin constituting the inner adhesive layer contains a polyolefin main chain can 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 inner layer adhesive may be the same as the resin used in the inner heat-sealable resin layer, and may be a polypropylene resin or a copolymer of propylene and ethylene.

From the viewpoint of long-term use stability of the packaging material for lithium ion batteries, the inner adhesive layer may be a resin composition containing an acid-modified polyolefin and a curing agent. The acid-modified polyolefin is particularly preferably a maleic anhydride-or acrylic acid-modified polyolefin.

The curing agent is not particularly limited as long as it is a curing agent for curing the acid-modified polyolefin. Curing agents such as epoxy curing agents, polyfunctional isocyanate curing agents, carbodiimide curing agents, and oxazoline curing agents 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 polyglycerol polyglycidyl ether are used.

The polyfunctional isocyanate curing agent is not particularly limited as long as it is a compound having 2 or more isocyanate groups in the molecule. For example, isophorone diisocyanate (IPDI), Hexamethylene Diisocyanate (HDI), Toluene Diisocyanate (TDI), polymerized or added components of diphenylmethane diisocyanate (MDI) or the like, or reactants of such mixtures with other polymers, are used.

The carbodiimide-based curing agent is not particularly limited as long as it is a compound having at least 1 carbodiimide group (-N ═ C ═ N-) in the molecule. Polycarbodiimide compounds having at least 2 or more carbodiimide groups are preferred.

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 adhesion between the inner adhesive layer and the inner heat-fusible layer.

The thickness of the inner adhesive layer is not particularly limited as long as it functions as an adhesive layer, and is preferably about 1 to 80 μm, and more preferably about 1 to 50 μm.

The inner layer adhesive layer may be formed by a solution type inner layer adhesive layer or a hot melt type inner layer adhesive layer when the intermediate metal layer and the inner heat-fusible resin layer are laminated.

The main component of the inner layer adhesive layer of the invention is one of modified polyolefin resin, block copolymerized propylene resin (B-PP) with polypropylene (PP) content more than 50%, random copolymerized propylene resin (R-PP) and homogeneous polypropylene resin (H-PP), which is a single layer or more than two layers of film layers composed of mixture of more than two.

Polypropylene has swelling but insolubilizing properties in the case of electrolyte penetration. If the content is less than 50%, the other additive components are affected by the electrolyte solution, and the possibility of swelling and dissolution increases, so that the inner layer adhesive layer dissolves in the electrolyte solution during long-term storage, and the strength of the intermediate metal layer and the internal heat adhesive layer cannot be maintained.

The inner layer adhesive layer of the present invention is formed by dissolving an acid-denatured polyolefin resin as a main agent and one or more kinds of isocyanate, epoxy resin, oxyphosphates, amine compounds, or the like as a curing agent in at least one or more kinds of solvents such as water, ethanol, isopropanol, ethyl acetate, methyl ethyl ketone, toluene methylcyclohexane, or the like, uniformly applying the solution to the surface of the metal subjected to the corrosion prevention treatment, heating the solution, and then volatilizing the solvent to obtain a desired thickness of the inner layer adhesive layer.

The inner layer adhesive layer of the present invention is preferably about 1 to 10 μm, more preferably 1 to 5 μm. When the thickness is less than 1 μm, the thickness becomes thin, the adhesion between the intermediate metal layer and the inner heat-fusible layer is lowered, and the adhesion becomes a problem. When the thickness exceeds 10 μm, there is no problem in adhesion, but when the curing agent is reacted, a hard resin layer is formed, the bending resistance is deteriorated, the flexibility of the metal composite film is lowered, cracks may be generated during bending, and the intermediate metal layer and the internal heat fusion layer may be peeled off. The preferred curing agent of the invention contains more than 50% of a mixture of isocyanurate derivatives of Pentamethylene Diisocyanate (PDI) or isocyanurate derivatives of Pentamethylene Diisocyanate (PDI) and allophanate (allophane) of pentamethylene diisocyanate, and the preferred amine compound is one or more than one of triethylamine and dimethylethanolamine. Wherein the functionality of the pentamethylene diisocyanate is between 3.0 and 4.5.

When the content of the Pentamethylene Diisocyanate (PDI) isocyanurate derivative or the isocyanurate derivative of Pentamethylene Diisocyanate (PDI) and the allophanate (allophanate) derivative of pentamethylene diisocyanate is less than 50%, the electrolyte resistance and acid resistance of the cured inner adhesive layer become low, the inner layer adhesive layer is easily dissolved, and the adhesiveness to the passivation layer or the inner layer heat-bonding layer becomes poor.

Further, if the functionality of pentamethylene diisocyanate is less than 3, many linear reaction products are generated. The linear reaction product is likely to be decomposed by permeation of the electrolyte and the generated hydrofluoric acid. When the functional group degree exceeds 4.5, the amount of the linear reactive component decreases, and the amount of the reaction product in a state of a dense three-dimensional structure increases. When a honey-like structure is generated, the internal stress of the adhesive layer increases, and the peel strength between the intermediate metal layer and the heat-fusion bonding layer tends to decrease.

Examples of the acid-denatured polypropylene acid-denaturing agent used in the inner adhesive layer of the present invention include anhydrous maleic acid, linolenic acid, methacrylic acid, acrylic acid, and succinic acid. Further, the acid-denatured polypropylene resin has a melting point of 60 to 97 ℃, preferably 75 to 90 ℃ and a weight-average molecular weight of 6000-. The acid value of the inner layer adhesive used in the inner layer adhesive layer is 0.5 to 5.0mgKOH/g, preferably 1.0 to 3.0 mgKOH/g. If the melting point is less than 60 ℃, the heat resistance is low, and the intermediate metal layer and the internally heated molten resin layer may be peeled off at a high temperature. If the temperature exceeds 97 ℃, the heat resistance is good, but when the temperature is reacted with a curing agent, a hard resin layer is formed, and the flexibility of the metal composite film is lowered due to poor bendability, so that cracks are generated at bending, and the intermediate metal layer and the inner heat fusion layer may be peeled off. When the weight average molecular weight is less than 6000, the fluidity of the resin is high during heating, the thickness is remarkably small during heat sealing, the adhesion strength between the intermediate metal layer and the inner heat fusion layer (in the case of adding a curing agent reaction) is reduced, and the sealing property is problematic. When the weight average molecular weight exceeds 80000, the intermediate metal layer and the internal heat fusion layer (in the case of adding a curing agent to react) form a hard resin layer, the bending resistance is deteriorated, the flexibility of the metal composite film is reduced, or cracks are generated by breaking, and the intermediate metal layer and the internal heat fusion layer may be peeled off. When the acid value of the acid-modified polyolefin resin is less than 0.5mgKOH/g, the curing reaction with the curing agent is small, and the adhesiveness between the intermediate metal layer and the inner heat-fusible layer is unstable. When the acid value exceeds 5.0mgKOH/g, the curing reaction between the curing agent and the acid-modified polyolefin resin becomes too high, a hard resin layer is formed, the bending resistance is deteriorated, the flexibility of the metal composite film is lowered, cracks are generated at the bending, and the intermediate metal layer and the inner heat-sealing layer may be peeled off.

Internal heat welding layer:

in the exterior material for a lithium ion battery of the present invention, the internal heat fusion layer corresponds to the innermost layer and is a layer (heat seal layer) that functions to seal the battery element by thermally fusing the heat-fusible resin layers to each other when the battery is assembled.

The resin constituting the inner heat-fusible layer is not particularly limited, and is mainly heat-fusible, and a resin having a polyolefin main chain such as polyolefin and 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 copolymer (for example, a block copolymer of propylene and ethylene), and polypropylene random copolymer (for example, a random copolymer of propylene and ethylene); propylene- α -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-based resins may be used alone in 1 kind, or may be used in 2 or more kinds.

The acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization with a polyolefin using an acid component. As the acid-modified polyolefin, a copolymer obtained by copolymerizing the above polyolefin with a polar molecule such as polyacrylic acid or methacrylic acid, or the like, may be used. In addition, as the acid component used for acid modification, carboxylic acids or sulfonic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, and anhydrides thereof can be used, and acrylic acid, maleic acid, and anhydrides thereof are preferably used.

The internal heat fusion layer may be composed of 1 resin alone, or may be composed of a combination of 2 or more resins. The inner heat-sealing layer may have only 1 layer, or may be composed of 2 or more layers of the same or different resins.

The inner heat-sealing layer may contain a slipping agent or the like as required. When the internal thermal bonding layer contains a slipping agent, the moldability of the exterior material for lithium ion batteries can be improved. The type of the slipping agent is not particularly limited and may be selected from known ranges. The slipping agent can be used alone 1 kind, or 2 kinds or more.

The lubricant is not particularly limited, but an amide-based lubricant is preferably used. The slipping agent can be used alone 1 kind, or 2 kinds or more.

When a slipping agent is present on the surface of the inner heat-sealing layer, the content thereof is not particularly limited, but from the viewpoint of improving moldability of the material for electronic packaging, 10 to 50mg/m2 is preferably used, and 15 to 40mg/m2 is more preferably used.

The slipping agent present on the surface of the internal heat fusion layer may be one that bleeds out from the resin constituting the internal heat fusion layer, or one that is applied to the surface of the internal heat fusion layer.

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

The inner heat-sealing layer may contain an antioxidant or the like as needed. The internal heat fusion layer containing an antioxidant can suppress thermal deterioration in the production process. The kind of the antioxidant is not particularly limited, and may be selected from known ranges. The antioxidant may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

The internal heat welding resin is a single layer or a composite layer composed of one or a mixture of two or more of acid-denatured polyolefin resin, homogeneous polypropylene resin, block copolymerized propylene resin, random copolymerized propylene resin and polyethylene resin.

The resin used for the internal heat fusion layer has a melting point of 120-162 ℃, more preferably 130-162 ℃, MFR (230 ℃) of 2-15g/10min, more preferably 3-12g/10min, and a thickness of 20-120 μm, more preferably 25-80 μm. When the inner heat-seal layer is a composite layer, the thickness of the back-side resin in contact with the intermediate metal layer is 2 μm or more, and the melting point is 130-152 ℃. When the melting point is 120 ℃ or lower, the fluidity during heating is high, the thickness becomes thin during pressure heat sealing, and the adhesion to the intermediate metal layer is reduced. In addition, the resin in the pressed portion of the battery flows to the edge portion which is not pressed by the pressing, cracks are generated due to external force of expansion and contraction of the battery, bending processing, and the like, and the electrolyte penetrates into the intermediate metal layer through the cracks, so that the insulation resistance of the internal thermal-bonding resin layer is reduced, a leakage phenomenon occurs, and the battery life is shortened. When the melting point exceeds 162 ℃, the crystallinity of the resin is improved, the fluidity at the time of pressure heat sealing is relatively lowered, and the heat resistance is improved, but the high crystalline resin forms a hard and brittle resin layer after heat sealing. Therefore, cracks are likely to occur in the resin layer due to external forces such as expansion and contraction of the battery and bending, and stable sealing properties over a long period of time cannot be obtained. When the resin MFR (230 ℃) is less than 2g/10min, the fluidity of the resin is low at the time of pressure heat sealing, and it is difficult to obtain stable sealing properties. When the MFR (230 ℃) of the resin exceeds 15g/10min, the fluidity of the resin becomes high at the time of pressure heat sealing, the thickness of the resin becomes thin, and the sealing property also becomes unstable. Further, the resin in the pressed portion inside the battery flows to the edge portion not pressed by the pressing, and cracks are generated due to external force of expansion and contraction of the battery, bending processing, or the like, and the electrolyte penetrates into the intermediate metal layer through the cracks, so that the insulation resistance of the internal heat-fusion resin layer is lowered, a leakage phenomenon occurs, and the battery life is shortened. When the thickness of the inner heat fusion layer is less than 20 μm, the thickness cannot sufficiently cover variations in machining dimensions and variations in conditions of a heat fusion device or the like, and thus it is difficult to obtain a uniform heat fusion portion, and stable sealing properties cannot be obtained. In addition, by pressurizing the resin flow of the pressed part in the battery to the non-pressed edge part, the thickness of the internal heat fusion layer becomes thin, cracks are easily caused by expansion and contraction of the battery, external force of bending processing and the like, the electrolyte penetrates into the intermediate metal layer through the cracks, the insulation resistance of the internal heat fusion layer is reduced, electric leakage occurs, and the service life of the battery is shortened. When the thickness of the internal heat fusion layer exceeds 120 μm, the amount of water vapor transmission increases, the internal moisture of the battery increases, gas is generated by reaction with the electrolyte, the risk of expansion, rupture, and leakage easily occurs, the battery life decreases, the adhesion strength between the intermediate metal layer and the internal heat fusion layer of the metal layer subjected to corrosion prevention treatment by excess hydrogen fluoride decreases, and leakage of the electrolyte easily occurs.

A composite process:

deoiling treatment of metal: the surface wettability of the intermediate metal layer 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 of the intermediate metal layer and the surface water contact angle exceed a predetermined range, rolling oil may remain on the surface in the production stage, which may deteriorate the interfacial adhesion capability formed between the anticorrosive layer, the intermediate metal layer, and the internal heat fusion layer, and the interfacial adhesion capability formed between the intermediate metal layer and the internal heat fusion layer may deteriorate during long-term storage of the battery, resulting in a risk of separation, and thus, leakage of the battery may easily occur. As a preventive measure, a method of performing heat treatment (annealing treatment) at 150 ℃ or higher after rolling, a plasma treatment method, or degreasing with alkali solution to remove residual oil on the surface can be used. The alkali degreasing method comprises the steps of immersing metal into 50-65 ℃ alkali liquor, washing with deionized water twice after certain time treatment, and drying to obtain the metal without grease;

and (3) corrosion prevention treatment of metal: coating a corrosion-proof liquid on at least one surface of the metal layer, which is at least connected with the internal heat welding layer, and then carrying out heat treatment at high temperature for a certain time;

coating and compounding of the outer-layer adhesive: coating an outer layer adhesive dissolved by an organic solvent between the metal layer and the outer layer base material resin layer, baking for a period of time at a certain temperature to volatilize the organic solvent to form an outer adhesive layer, compounding the middle metal layer and the outer base material resin layer at a certain temperature and pressure, curing for a period of time at a certain temperature to cure the outer adhesive layer to obtain the composite resin consisting of the outer base material resin layer, the outer adhesive layer and the middle metal layer. In the case where no outer layer adhesive is used for the lamination of the outer base resin layer and the intermediate metal layer, the intermediate metal layer and the outer base resin layer are laminated by heating and pressing, and the outer base resin layer and the intermediate metal layer are bonded by heat treatment, ultraviolet treatment, electron beam treatment, or the like, whereby a composite resin layer composed of the outer base resin layer and the intermediate metal layer can be obtained.

Compounding internal heat welding resin: in the present invention, there are 2 types of methods for forming the inner heat seal layer in the composite film formed by laminating the outer base resin. The method specifically comprises the following steps: a. dry compounding method: the method is mainly characterized in that a mixture of solution type acid modified polypropylene and aromatic isocyanate solution is coated on a metal surface which is compounded with outer base material resin and subjected to anticorrosion treatment, a bonding layer is formed after drying, the bonding layer is thermally compounded with the bonding surface of the thermal welding resin at a certain temperature, and then curing treatment is carried out. Forming a composite finished product of an outer base material resin layer/an outer adhesive layer/an intermediate metal layer/an inner adhesive layer/an inner heat-sealing layer. The adhesive surface of the hot-melt resin film in contact with the inner adhesive layer is subjected to corona treatment in advance; b. a heat bonding method: dissolving reactive acid modified polypropylene with the melting point of more than 145 ℃ into the solution, and then adding epoxy resin and methanesulfonic acid resin to obtain the adhesive resin glue solution. The composite product of the outer base material resin layer/the outer adhesive layer/the middle metal layer/the inner adhesive layer/the inner heat-sealing layer is formed by uniformly coating a mixed glue solution of reactive acid modified polypropylene, epoxy resin and methanesulfonic acid resin as a cross-linking agent on an antiseptic treated metal surface of a composite film compounded with the outer base material resin, drying to form a bonding layer, thermally compounding the bonding layer with a corona treated surface of the inner heat-sealing resin, and further thermally treating at a high temperature for a certain time.

The test method comprises the following steps:

(1) inner layer adhesive resin melting point measurement

The test was carried out using a Differential Scanning Calorimeter (Differential Scanning Calorimeter), and the temperature increase and decrease rates were set at 10 ℃/min, and four stages were set: 1. heating to 150 deg.C at 25 deg.C, cooling to 25 deg.C at 2 deg.C and 150 deg.C, and heating to 150 deg.C at 3 deg.C and 25 deg.C. 4. The melting point was obtained by measuring the peak top temperature of the second endothermic peak at 150 ℃ down to 25 ℃.

(2) Molecular weight measurement of inner layer adhesive resin

The weight average molecular weight Mw of the polymeric resin was measured using high temperature GPC;

and (3) testing conditions are as follows: and (3) testing temperature: 150 ℃; mobile phase: trichlorobenzene (TCB); and (3) standard substance: polystyrene (PS); sample system: polyolefin samples, common samples PP and PE; the test sample amount: 5 mg;

the instrument model is as follows: PL-GPC 220; the type of the chromatographic column: PLGel MIXED-B LS300x7.5mm; a detector: a differential refractive detector;

sample preparation: the sample is completely dissolved in trichlorobenzene, filtered by an organic filter membrane of 0.22um and then directly tested on a machine, and the test value of the weight average molecular weight Mw is directly read.

(3) And measuring the acid value of the inner bonding layer.

Dissolving the inner-layer adhesive into a sample solution by using an organic solvent, neutralizing the titration sample solution by using a standard titration solution of potassium hydroxide (KOH) or sodium hydroxide (NaOH), judging a titration end point according to the corresponding color change of the indicator, and finally calculating the acid value of the sample solution according to the volume of the standard titration solution consumed by the end point. The calculation formula is as follows:

Δ V: titration of the number of KOH or NaOH volumes consumed (ml)

C: molar concentration (mol/L) of KOH or NaOH standard solutions

m: mass (g) of resin

(4) Initial peel strength test

And preparing the finished metal composite film into a straight strip shape, wherein the size of a sample strip is 100 x 15mm, and performing T-shaped stripping measurement on two stripping surfaces at a drawing speed of 50mm/min by using a drawing test device. 5 bars/group were tested in parallel.

(5) Electrolyte resistance test of finished product

Directly soaking a metal composite film finished sample bar in a solution containing 1mol/L LiPF₆Dimethyl carbonate (DMC): diethyl carbonate (DEC): soaking the sample in a mixed solvent with the weight ratio of Ethylene Carbonate (EC) substances of 1:1:1 at 85 ℃ for 3 days, taking out, washing with water for 15min, wiping off the moisture on the surface of the sample, and measuring the peel strength between the metal layer and the inner welding resin layer according to the method of an initial peel strength test.

(6) Finished product water-adding electrolyte resistance test

Stripping the metal/inner welding resin composite layer of the metal composite film finished product sample bar for a short section, and soaking in dimethyl carbonate (DMC) containing 1mol/L LiPF 6: diethyl carbonate (DEC): adding 1000PPM water accounting for the total mass of the electrolyte into a mixed solvent with the mass ratio of Ethylene Carbonate (EC) substances being 1:1:1, soaking at the temperature of 85 ℃ for 3 days, taking out, washing with water for 15min, not wiping off water, and measuring the peel strength between the metal layer and the inner welding resin layer according to the method of an initial peel strength test.

The following provides specific embodiments of a high electrolyte resistance lithium ion battery device packaging material and battery of the present invention:

composite formation

The composite product consists of an outer base material resin layer, an outer adhesive layer, an intermediate metal layer, an inner adhesive layer and an inner heat-sealing layer.

The lamination method is as follows: and carrying out corona treatment on the resin film of the outer substrate layer in contact with the outer adhesive layer. Specifically, a two-component polyurethane adhesive (polyurethane-modified polyester polyol or polyester polyol and an aromatic isocyanate compound) is applied to one surface of a metal foil (aluminum foil, nickel-plated iron foil, stainless steel foil, or the like) to form an adhesive layer on the metal foil. And thermally compounding the outer adhesive layer on the metal foil and the outer base resin film, and curing at 60 ℃ for 3 days to form an outer base resin layer/outer adhesive layer/metal layer semi-finished product. Both sides of the metal layer are previously subjected to an anticorrosive treatment.

The outer layer adhesive of the following formulation was applied to one side of the metal foil:

mixing non-crystalline polyester polyol with the weight-average molecular weight of 8000, the Tg of 79 ℃ and the hydroxyl value of 16mg KOH/g with non-crystalline polyester polyol with the weight-average molecular weight of 6500, the Tg of-3 ℃ and the hydroxyl value of 10mg KOH/g according to the weight ratio of 10:5, and adding toluene diisocyanate to form mixed outer-layer binding solution with the NCO/OH ratio of 21;

both sides of the metal are pre-treated for corrosion protection.

Uniformly coating the anti-corrosion liquid on two surfaces of the aluminum foil by a coating roller according to a certain proportion, and then baking for 2min at 190 ℃, wherein the coating wet film amount of the anti-corrosion layer treatment liquid is 5g/m²In examples 1 to 4, 6 and 7 and comparative examples 1, 2 and 3, the surface of the aluminum foil was coated with Cr in an amount of 15mg/m²。

Inner adhesive layer compounding mode

The obtained semi-finished product: and an inner adhesive layer is compounded on the metal surface of the outer base material resin layer/the outer adhesive layer/the middle metal layer. The inner adhesive layer is a two-component adhesive. Adopting a dry compounding method: the composite product of the outer base material resin layer/the outer adhesive layer/the middle metal layer/the inner adhesive layer/the inner heat-sealing layer is formed by coating a mixture of solvent type acid modified polypropylene and a curing agent on a metal surface which is compounded with outer base material resin and subjected to antiseptic treatment, drying to form a bonding layer, thermally compounding the bonding layer with the bonding surface of the heat-sealing resin at the temperature of 90 ℃, and curing at the temperature of 50 ℃ for 7 days. The adhesive surface of the heat-fusible resin film in contact with the inner adhesive layer is subjected to corona treatment in advance.

Internal heat welding layer

And (3) finishing compounding the semi-finished product packaging material of the outer base material resin layer/the outer adhesive layer/the middle metal layer/the inner adhesive layer with the inner heat welding layer in a dry compounding way, and aging for three days at the temperature of 60 ℃ to obtain the finished product lithium ion battery device external packaging material. The specific formula of the internal heat welding layer is as follows:

the internally heat-sealing resin consists of three layers, the surface contacting with the internal adhesive layer is processed by corona treatment, and the structure is as follows:

resin layer in contact with inner adhesive layer: a layer composed of a random copolymerized polypropylene having a melting point of 151 ℃ and an MFR (230 ℃) of 5.5g/10 min;

an intermediate resin layer: 50 wt% of block copolymer polypropylene having a melting point of 162 ℃ and an MFR (230 ℃) of 2g/10 min; 20% of a random copolymer polypropylene having a melting point of 155 ℃ and an MFR (230 ℃) of 5g/10 min; 20% having a melting point of 160 ℃, an MFR (230 ℃) of 9.5g/10min and a density of 0.87g/cm³A mixture layer of the propylene-butene-based polymer elastomer of (1) and a 10% amorphous propylene-based elastomer having an MFR (230 ℃) of 3g/10 min.

Innermost resin layer: a layer composed of a random copolymerized polypropylene having a melting point of 145 ℃ and an MFR (230 ℃) of 12g/10 min;

the thickness ratio of three layers of resin from the contact layer with the inner adhesive layer to the innermost layer in the internal heat welding resin is 3:6: 1.

Example 1

The outer substrate layer is a 25 μm biaxially oriented nylon film which is compounded to an 8021 series aluminum material with the surface wettability of 68dyn/cm and the thickness of 35 μm through an outer adhesive. And performing anticorrosion treatment on two surfaces of the metal foil to form an anticorrosion layer.

And (4) carrying out anticorrosion treatment on the metal foil by using the anticorrosion liquid on the two sides. The content ratio of trivalent chromium compound, inorganic acid and organic resin on the surface of the aluminum foil is 2:2: 1. the trivalent chromium compound is chromium phosphate, the inorganic acid is nitric acid, and the organic resin is polyacrylic resin.

The internal heat welding layer is prepared by adding 100 mass percent of pentamethylene diisocyanate into modified polypropylene with the weight average molecular weight of 7000, the content of crystalline polypropylene of which is 55 percent, the melting point of 65 ℃ and the acid value of 2mgKOH/g to prepare an internal adhesive, and compounding the internal adhesive on a semi-finished product to obtain a finished product. Wherein the pentamethylene diisocyanate used has a functionality of 3.3.

Example 2

The outer substrate layer is a 25 μm biaxially oriented nylon film which is compounded to a 40 μm thick 8079 series aluminum material with a surface wettability of 70dyn/cm by an outer adhesive. The two sides of the metal foil are subjected to antiseptic treatment in advance to form an antiseptic layer.

And (4) carrying out anticorrosion treatment on the metal foil by using the anticorrosion liquid on the two sides. The content ratio of the trivalent chromium compound, the inorganic acid and the organic resin on the surface of the aluminum foil is 3:1:2 on the surface of the metal foil. The trivalent chromium compound is prepared by mixing chromium nitrate and chromium fluoride according to a ratio of 1:1, the inorganic acid is prepared by mixing phosphoric acid and nitric acid according to a ratio of 1:1, and the organic resin is prepared by mixing polyvinyl alcohol and polyacrylic resin according to a ratio of 2: 8.

The inner heat-sealing layer is prepared by compounding an inner adhesive obtained by adding 100 mass percent of pentamethylene diisocyanate serving as a curing agent into modified polypropylene with the weight-average molecular weight of 24000, the content of crystalline polypropylene of which is 75 percent, the melting point of which is 75 ℃ and the acid value of which is 4.6mgKOH/g, and the semi-finished product with the inner adhesive obtained by-NCO/-OH ═ 3. Wherein the functionality of the pentamethylene diisocyanate used is 3.0.

Example 3

The outer substrate layer material is a two-way synchronous stretching nylon film with the thickness of 25 mu m, the two-way synchronous stretching nylon film is compounded on a stainless steel foil with the thickness of 38 mu m after heat treatment through an outer layer adhesive, and the surface water contact angle is 15 degrees. The two sides of the metal foil are subjected to antiseptic treatment in advance to form an antiseptic layer.

And (4) carrying out anticorrosion treatment on the metal foil by using the anticorrosion liquid on the two sides. The content ratio of the trivalent chromium compound, the inorganic acid and the organic resin on the surface of the metal foil is 15:1: 5. The trivalent chromium compound is chromium fluoride, the inorganic acid is hydrofluoric acid, and the organic resin is polyvinyl alcohol resin.

The inner heat-sealing layer is compounded on a semi-finished product through modified polypropylene with the weight-average molecular weight of 68000, the content of crystalline polypropylene of which is 85 percent, the melting point of 80 ℃ and the acid value of 3mgKOH/g, and an inner adhesive which is obtained by adding a mixture of 80 mass percent of pentamethylene diisocyanate and 20 mass percent of allophanate modified pentamethylene diisocyanate as a curing agent to obtain a finished product. Wherein the functionality of the pentamethylene diisocyanate is 3.5.

Example 4

The outer substrate layer material is a 25 μm biaxially oriented nylon film which is compounded to a 50 μm thick steel plate with a surface degree of 1 μm nickel layer having a surface wettability of 72dyn/cm by an outer adhesive. The two sides of the metal foil are subjected to antiseptic treatment in advance to form an antiseptic layer.

And (4) carrying out anticorrosion treatment on the metal foil by using the anticorrosion liquid on the two sides. The content ratio of the trivalent chromium compound, the inorganic acid and the organic resin on the surface of the metal foil is 3:1: 2. The trivalent chromium compound is chromium nitrate, the inorganic acid is phosphoric acid, and the organic resin is polyacrylic resin.

The inner heat welding layer is compounded to a semi-finished product through modified polypropylene with the weight-average molecular weight of 78000, the content of crystalline polypropylene of 75 percent, the melting point of 88 ℃ and the acid value of 1.4mgKOH/g, and an inner adhesive prepared by adding a mixture of 75 mass percent of pentamethylene diisocyanate and 25 mass percent of hexamethylene diisocyanate as a curing agent to the semi-finished product to obtain a finished product. Wherein the functionality of the pentamethylene diisocyanate is 3.3.

Example 5

The outer substrate layer is a 25-micron biaxially oriented nylon film which is compounded on the 8021 series aluminum material with the thickness of 40 microns and the surface water contact angle of 15 degrees through the outer adhesive. The two sides of the metal foil are subjected to antiseptic treatment in advance to form an antiseptic layer. The anticorrosive layer was formed by forming 0.1 μ thick layers of 95 wt% cerium oxide (CeO2) and 5 wt% aminopropyltrimethoxysilane on both sides of the middle metal layer, and further forming 0.1 μ thick layers of an epichlorohydrin adduct of polyallylamine resin and 1, 6-hexanediol on the above layers.

The internal heat welding layer is compounded on a semi-finished product to obtain a finished product by adding a mixture of 75 mass percent of modified pentamethylene diisocyanate and 25 mass percent of hexamethylene diisocyanate as a curing agent into modified polypropylene with the weight-average molecular weight of 65000, the content of crystalline polypropylene of which is 95 percent, the melting point of 88 ℃ and the acid value of 1.4mgKOH/g, and compounding an internal adhesive of-NCO/-OH ═ 3 on the semi-finished product. Wherein the functionality of the pentamethylene diisocyanate is 4.5.

Example 6

The outer substrate layer is made of a 25 mu m biaxially oriented nylon film, and is compounded on an 8079 series aluminum material with the surface wettability of 70dyn/cm and the thickness of 80 mu m through an outer layer adhesive. The two sides of the metal foil are subjected to antiseptic treatment in advance to form an antiseptic layer. The content ratio of the trivalent chromium compound, the inorganic acid, the fluoride and the aminated phenol resin on the surface of the metal foil is 15:2:2: 3. The trivalent chromium compound is chromium nitrate and the inorganic acid is phosphoric acid.

The internal heat welding layer is compounded on a semi-finished product to obtain a finished product by adding a mixture consisting of 60 mass percent of pentamethylene diisocyanate and 40 mass percent of hexamethylene isocyanate as a curing agent into modified polypropylene with the weight-average molecular weight of 35000, the content of crystalline polypropylene of which is 92 percent, the melting point of 75 ℃ and the acid value of 1.5mgKOH/g, and compounding the internal adhesive of-NCO/-OH ═ 3 on the semi-finished product. Wherein the functionality of the pentamethylene diisocyanate is 3.8.

Example 7

The outer substrate layer is a 25 μm biaxially oriented nylon film which is compounded to a 50 μm thick 8021 series aluminum foil with a surface water contact angle of 10 degrees by an outer layer adhesive. The two sides of the metal foil are subjected to antiseptic treatment in advance to form an antiseptic layer.

And (4) carrying out anticorrosion treatment on the metal foil by using the anticorrosion liquid on the two sides. The content ratio of the trivalent chromium compound, the inorganic acid and the organic resin on the surface of the metal foil is 3:1: 2. the trivalent chromium compound is obtained by mixing chromium nitrate and chromium fluoride according to the ratio of 1:2, the inorganic acid is nitric acid, and the organic resin is polyacrylic resin.

The internal heat welding layer is compounded on a semi-finished product to obtain a finished product by adding a curing agent consisting of 80 mass percent of pentamethylene diisocyanate and 20 mass percent of Toluene Diisocyanate (TDI) into modified polypropylene with the weight-average molecular weight of 78000, the content of crystalline polypropylene of which is 92 percent, the melting point of 92 ℃ and the acid value of 3mgKOH/g, and then compounding the internal adhesive with the semi-finished product to obtain the-NCO/-OH ═ 3. Wherein the functionality of the pentamethylene diisocyanate is 3.3.

Comparing examples 1, 3, 4 and 5, it was found that increasing the content of the crystalline polypropylene resin in the adhesive layer resin improved the initial peel strength, indicating that a higher content of the crystalline polypropylene resin improved the peel strength between the inner heat-sealing layer and the intermediate metal layer.

Comparing examples 3 to 6, it was found that increasing the content of pentamethylene diisocyanate or a mixture of pentamethylene diisocyanate and allophanate thereof, the peel strength maintenance rate of the 3-day electrolyte resistance test and the 3-day electrolyte resistance test with water added was increased, indicating that increasing the content of pentamethylene diisocyanate can improve the electrolyte resistance of the inner layer thermal bonding layer and the intermediate metal layer.

In comparison of examples 1, 2, 4 and 5, it was found that the initial peel strength of the inner layer heat-seal layer and the intermediate metal layer was gradually increased by increasing the molecular weight of the inner layer adhesive resin, indicating that the peel strength of the inner layer heat-seal layer and the intermediate metal layer could be increased by increasing the molecular weight of the inner layer adhesive resin.

Comparative example 1

The resin of the outer substrate layer is a 25-micron biaxially oriented nylon film, and the outer substrate layer is compounded on a 40-micron 8021 series aluminum foil with a surface water contact angle of 10 degrees through an outer layer adhesive to obtain a semi-finished product. The surface of the aluminum foil is treated by using an anti-corrosion solution. The two sides of the metal foil are pre-treated with corrosion-resistant treatment to form corrosion-resistant layers

And (4) carrying out anticorrosion treatment on the metal foil by using the anticorrosion liquid on the two sides. The content ratio of the trivalent chromium compound, the inorganic acid, the fluoride and the aminated phenol resin on the surface of the metal foil is 15:2:2: 3. The trivalent chromium compound is chromium nitrate and the inorganic acid is phosphoric acid.

The internal heat welding layer is prepared by compounding modified polypropylene with the weight-average molecular weight of 80000, the content of crystalline polypropylene of which is 30%, the melting point of which is 50 ℃ and the acid value of which is 3mgKOH/g, and an inner-layer adhesive of-NCO/-OH ═ 3 prepared by taking 100% of pentamethylene diisocyanate as a curing agent in parts by mass onto a semi-finished product. Wherein the functionality of the pentamethylene diisocyanate is 2.8.

Comparative example 2

The resin of the outer substrate layer is a 25-micron biaxially oriented nylon film, and the outer substrate layer is compounded on a 40-micron 8021 series aluminum foil with a surface water contact angle of 10 degrees through an outer layer adhesive to obtain a semi-finished product. The two sides of the metal foil are subjected to antiseptic treatment in advance to form an antiseptic layer.

And (4) carrying out anticorrosion treatment on the metal foil by using the anticorrosion liquid on the two sides. The content ratio of the trivalent chromium compound, the inorganic acid and the organic resin on the surface of the metal foil is 2:2: 1. The trivalent chromium compound is chromium phosphate, the inorganic acid is nitric acid, and the organic resin is polyacrylic resin.

The inner heat welding layer is prepared by compounding modified polypropylene with weight average molecular weight of 5600, crystalline polypropylene content of 95%, melting point of 120 ℃ and acid value of 0.3mgKOH/g and inner layer adhesive of-NCO/-OH ═ 3 prepared by 100% by mass of pentamethylene diisocyanate as curing agent on the semi-finished product. Wherein the functionality of the pentamethylene diisocyanate is 4.7.

Comparative example 3

The inner heat-sealing layer is prepared by compounding modified polypropylene with the weight-average molecular weight of 78000, the crystalline polypropylene content of 92 percent, the melting point of 88 ℃ and the acid value of 5.4mgKOH/g and an inner-layer adhesive prepared by taking the mixture of 70 mass percent of Toluene Diisocyanate (TDI) and 30 mass percent of pentamethylene isocyanate as a curing agent onto a semi-finished product. Wherein the functionality of the pentamethylene diisocyanate is 4.7.

TABLE 1 evaluation results of peel strength between intermediate metal layer and inner heat welded layer

The above is statistics of the evaluation results of the peel strength between the intermediate metal layer and the internal heat welded layer in the examples and comparative examples of the present invention, wherein the maintenance rate refers to the ratio of the peel strength between the intermediate metal layer and the internal heat welded layer to the initial strength after electrolyte resistance.

Comparative example 1, the melting point of the inner layer adhesive was less than 60 c, in which the crystalline polypropylene content was less than 50% and the functionality of pentamethylene diisocyanate was 2.8. Although the peel strength is better under the initial condition, the peel strength is obviously reduced in a 3-day electrolyte resistance test and a 3-day electrolyte resistance test by adding water, and the maintenance rates are respectively 75.3% and 60.5%.

Comparative example 2, the inner layer adhesive had a higher viscosity due to a higher melting point, resulting in an unstable formation of the inner layer adhesive and thus a failure to obtain a good peel strength in the initial state; meanwhile, the functional degree of the pentamethylene diisocyanate used by the inner layer adhesive is 4.7, and the molecular weight and acid value of the resin are lower, so that the peel strength is greatly reduced in electrolyte resistance experiments and electrolyte resistance experiments by adding water, and the maintenance rates are only 73% and 59%, respectively.

Comparative example 3, the amount of pentamethylene isocyanate added was less than 50%. Although the adhesive layer has higher strength due to higher acid value in the initial stage, the cured adhesive layer is easy to break, and the peel strength is greatly reduced in the electrolyte resistance test of 3 days and the electrolyte resistance test of 3 days after adding water, and is only 72% and 59%, respectively.

The present invention is not intended to be limited to the particular embodiments shown and described, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein. The technical scope of the present invention is not limited to the content of the specification, and must be determined according to the scope of the claims.

Claims

1. An outer packaging material for an electrolyte-resistant lithium ion battery device, characterized in that: comprises an outer base material resin layer, an intermediate metal layer, an inner adhesive layer and an inner heat welding layer; the inner adhesive layer is formed by an adhesive containing acid modified polypropylene resin and a curing agent; the acid modified polypropylene resin is at least one of block copolymerization polypropylene, random copolymerization polypropylene and homopolymerization polypropylene, wherein the content of crystalline polypropylene is more than 50%.

2. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 1, characterized in that: the acid modifier used for the acid modified polypropylene resin is one of anhydrous maleic acid, methacrylic acid, acrylic acid and succinic acid.

3. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 1, characterized in that: the melting point of the acid modified polypropylene resin is between 60 and 97 ℃, and the weight average molecular weight is between 6000 and 80000.

4. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 3, characterized in that: the melting point of the acid modified polypropylene resin is between 75 and 90 ℃.

5. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 1, characterized in that: the acid value of the inner layer adhesive used in the inner adhesive layer is 0.5-5 mgKOH/g.

6. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 5, characterized in that: the acid value of the inner layer adhesive used in the inner layer adhesive layer is 1-3 mgKOH/g.

7. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 1, characterized in that: the curing agent is at least one of resin containing isocyanate component, epoxy resin, methanesulfonic acid resin and amine compound.

8. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 7, characterized in that: when the curing agent is a resin containing an isocyanate component, it is a mixture containing 50% or more of an isocyanate derivative of pentamethylene diisocyanate, or an isocyanate mixture of an isocyanate derivative of pentamethylene diisocyanate and an allophanate of pentamethylene diisocyanate; wherein the functionality of the pentamethylene diisocyanate is between 3.0 and 4.5.

9. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 1, characterized in that: at least one surface of the middle metal layer, which is in contact with the inner adhesive layer, is treated by a preservative solution; the corrosion-resistant liquid comprises, by mass, 19-60 parts of a trivalent chromium compound, 3-60 parts of an inorganic acid, 6-60 parts of an organic resin and 0-10 parts of a fluoride; the trivalent chromium compound at least comprises one of chromium nitrate, chromium phosphate and chromium chloride.

10. The exterior packaging material for an electrolyte-resistant lithium ion battery device according to claim 9, characterized in that: the inorganic acid is at least one of nitric acid and phosphoric acid; the fluoride is at least one of chromium fluoride and aluminum fluoride; the organic resin is composed of polyacrylic resin and polyvinyl alcohol; the polyacrylic resin is one or more of polyacrylic acid, polymethyl acrylate, a copolymer of acrylic acid and maleic acid, a copolymer of acrylic acid and styrene and sodium salt and ammonium salt derivatives thereof, and the weight average molecular weight of the polyacrylic resin is 10000-800000.

11. The exterior material for an electrolyte-resistant lithium ion battery device according to claim 1, characterized in that: and an outer anti-corrosion layer is arranged on one side of the middle metal layer, which is in contact with the outer base material resin layer.

12. A battery, characterized by: the use of the electrolyte-resistant lithium ion battery pack outer packaging material according to any one of claims 1 to 11.