WO2023093072A1

WO2023093072A1 - Outer packaging material of electrolyte-resistant lithium ion battery device, and battery

Info

Publication number: WO2023093072A1
Application number: PCT/CN2022/104943
Authority: WO
Inventors: 庄志; 曹舒勇; 王小明; 冯宝平; 程跃
Original assignee: 江苏睿捷新材料科技有限公司
Priority date: 2021-11-26
Filing date: 2022-07-11
Publication date: 2023-06-01
Also published as: CN114156576A

Abstract

The present invention relates to the technical field of production of packaging materials of lithium ion batteries, and in particular to a packaging material of a lithium ion battery and a battery, wherein the packaging material comprises an inner adhesive layer (7) for improving the resistance to electrolyte stripping of a hot-melt resin layer (8) and an intermediate metal layer (5).

Description

A kind of outer packaging material and battery for electrolyte-resistant lithium-ion battery device

technical field

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

Background technique

At present, lithium-ion batteries are mainly divided into three categories: square, cylindrical, and soft packs. The square and cylindrical shells are mainly made of hard shells such as aluminum alloy and stainless steel. The aluminum alloy shell can be pure aluminum, while the shell of the soft pack is made of aluminum plastic. film, which greatly improves the problem of inflexible shape design of hard-mounted batteries.

The composition of the aluminum-plastic film from the outside to the inside is the outer substrate resin layer, the outer adhesive layer, the middle metal layer, the inner adhesive layer and the inner thermal fusion layer. As a battery outsourcing material, the aluminum-plastic film is required to be resistant to electrolyte corrosion, so as to prevent the battery pack from leaking and other problems and ensure the service life of the battery.

Generally, the inner thermal fusion layer and the middle metal layer in the outer packaging material for lithium-ion battery devices are bonded together by the inner adhesive layer to prevent delamination between the inner thermal fusion layer and the middle metal layer, and reduce the electrolyte and the middle metal layer. Contact, improve its service life and safety. Therefore, the adhesive in the outer packaging material of the lithium-ion battery device has a great influence on its service life and safety.

At present, the inner adhesive layer of lithium-ion battery outer packaging materials is mainly a solvent-based adhesive composed of acid-modified polypropylene and 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 using these inner adhesive layers can have a better maintenance of its bonding strength under the condition of ordinary electrolyte. However, part of the moisture in the environment will be absorbed in the electrolyte that has been placed for a long time, and the moisture dissolved in the electrolyte will react with the electrolyte to produce highly corrosive acids that will corrode the inner adhesive layer. Storage causes the electrolyte to dissolve in the inner adhesive layer causing it to expand, and the bond strength between the middle metal layer and the inner heat-welded layer decreases. As a result, the aluminum-plastic film is prone to interlayer separation, resulting in the risk of electrolyte leakage. In severe cases, thermal runaway of the battery will result in more serious losses, which will affect the popularization and application of the aluminum-plastic film in the field of lithium-ion batteries.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies of the prior art and provide an outer packaging material for lithium-ion battery devices with stronger electrolyte corrosion resistance.

To achieve the above object, technical solution of the present invention is achieved in that:

The object of the present invention is to provide an outer packaging material for an electrolyte-resistant lithium-ion battery device, comprising an outer substrate resin layer, an intermediate metal layer, an inner adhesive layer, and an inner heat-welding layer; the inner adhesive layer is composed of acid-modified Formed by an adhesive composed of polypropylene resin and a curing agent; the acid-modified polypropylene resin is at least one of block copolymerized polypropylene, random copolymerized polypropylene, and homopolypropylene with a crystalline polypropylene content greater than 50%. kind.

Further, the acid modifier used in the acid-modified polypropylene resin includes acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, crotonic acid, succinic acid, etc. , half-esters, half-amides, etc. of unsaturated dicarboxylic acids. Among them, acrylic acid, methacrylic acid, maleic acid, maleic anhydride, and succinic acid are preferable, and maleic anhydride and succinic acid are more particularly preferable. In addition, the form of the acid component is not limited as long as it is copolymerized with the polyolefin resin, and the state of the copolymerization includes random copolymerization, block copolymerization, graft copolymerization (graft modification), and copolymerization by thermal subtractive method. wait.

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

Furthermore, the melting point of the acid-modified polypropylene resin is between 75-90°C.

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

Furthermore, the inner layer adhesive used in the inner adhesive layer has an acid value of 1-3 mgKOH/g.

Further, the curing agent is at least one of resins containing isocyanate components, epoxy resins, methanesulfonic acid resins, and amine compounds.

Furthermore, when the curing agent is a resin containing isocyanate components, it is a mixture of isocyanate derivatives containing more than 50% of pentamethylene diisocyanate, or isocyanate derivatives of pentamethylene diisocyanate and pentamethylene diisocyanate Isocyanate mixtures of allophanates of methylene diisocyanate. Wherein, the functional group degree of the pentamethylene diisocyanate is between 3.0 and 4.5.

Here, a hydrogen bond is generated between the isocyanate group (-NCO) and the urethane group (-NHCOO-) and the material containing active hydrogen, which strengthens the intramolecular force and increases the bonding strength.

Further, at least the side where the middle metal layer is in contact with the inner adhesive layer is treated with an anti-corrosion solution; in parts by mass, in the anti-corrosion solution, there are 19-60 parts of trivalent chromium compound, 3-60 parts of inorganic acid, 6-60 parts of Organic resin, 0-10 parts of fluoride; the trivalent chromium compound is composed of at least one of chromium nitrate, chromium phosphate and chromium chloride.

Here, the trivalent chromium compound can form a coordination cross-linking structure centered on Cr atoms on the metal surface, which can increase the cross-linking degree of the anti-corrosion film on the metal surface.

Furthermore, the expression of the above-mentioned parts by mass is only within the formula range of certain examples, and the actual quality can be multiplied several times according to the size of the production volume. Therefore, the key is to limit the proportional relationship between the components in the preservative solution , that is, the ratio of the trivalent chromium compound, inorganic acid, organic resin, and 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 anti-corrosion film on the metal surface will become hard, and the folding resistance of the corresponding metal composite film will deteriorate. If bending or forming is performed, the anti-corrosion layer will crack , the entry of the electrolyte will lead to a decrease in insulation, and hydrogen fluoride corrosion will cause the peeling of the intermediate metal layer and the inner heat welding layer, resulting in leakage of the electrolyte; when the proportion of the trivalent chromium compound is lower than the above range, it will cause metal surface The anti-corrosion film has a low degree of cross-linking and cannot play the role of anti-corrosion.

Here, when the ratio of the inorganic acid exceeds the above-mentioned range, the ratio of the content of the trivalent chromium compound and the organic resin in the anticorrosion layer will decrease, and the anticorrosion layer with high corrosion resistance cannot be obtained, so that the corrosion resistance of hydrogen fluoride will be deteriorated. Poor, when the proportion of inorganic acid is lower than the above range, the oxide film on the metal surface will not be removed cleanly, and the adhesion between the anti-corrosion layer and the middle metal layer will become poor. In the long-term storage of the device, the middle metal layer and the inner thermal fusion layer may peel off.

Here, when the proportion of the organic resin is lower than the above range, the anticorrosion film on the metal surface will be delaminated and easily broken, and the corrosion resistance of the corresponding metal composite film will be deteriorated; when the proportion of the organic resin exceeds the above range, it will cause metal corrosion. If the surface anticorrosion film is too thick, it is also easy to break, and it is easy to absorb water, and it is easy to generate hydrofluoric acid in the electrolyte environment, which corrodes the metal surface, so the corrosion resistance of the corresponding metal composite film becomes poor.

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

Here, when the ratio of fluoride exceeds the above-mentioned range, the bridging property of trivalent chromium will become poor, which will affect the formation of the anti-corrosion layer, and the risk of peeling off between the intermediate metal layer and the inner thermal welding layer will also result in waste of resources; When the ratio of the fluoride is lower than the above range, the hydrofluoric acid corrosion resistance effect is poor, and the anticorrosion effect of protecting the metal surface cannot be obtained.

Furthermore, the inorganic acid is composed of at least one of nitric acid and phosphoric acid; the fluoride is composed of 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 of polyacrylic acid, polymethyl acrylate, copolymer of acrylic acid and maleic acid, copolymer of acrylic acid and styrene, and its sodium salt and ammonium salt derivatives one or more species.

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

Here, the polyacrylic resin plays a role of improving the film-forming property of the anticorrosion layer on the metal surface.

Here, the fluoride serves to increase the hydrofluoric acid resistance of the metal film.

Preferably, the weight average molecular weight of the polyacrylic resin is preferably about 10 million to 1 million, more preferably about 30 million to 800,000, and still more preferably about 10,000 to 800,000.

Here, the greater the weight-average molecular weight of the polyacrylic resin, the higher its durability, but the water solubility of the polyacrylic resin decreases and the coating liquid becomes unstable, affecting production stability. On the contrary, the smaller the weight average molecular weight of the polyacrylic resin, the lower its durability. When the weight-average molecular weight of the polyacrylic resin is 1,000 or more, its durability is high; when the weight-average molecular weight is 1 million or less, the coating stability during production is good.

Further, the outer packaging material for the electrolyte-resistant lithium-ion battery device also includes an outer adhesive layer between the outer substrate resin layer and the intermediate metal layer; the outer layer adhesive used in the outer adhesive layer is a double-pack One or more components of polyester polyol and isocyanate solvent; the thickness of the outer adhesive layer is 2-5 μm.

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

Further, it also includes that the side of the middle metal layer in contact with the outer adhesive layer is provided with an outer anti-corrosion layer.

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

Further, the outer packaging material for the electrolyte-resistant lithium-ion battery device further includes an outer anti-corrosion layer on the side where the intermediate metal layer is in contact with the outer substrate resin layer.

Another object of the present invention is to provide a battery using any of the above electrolyte-resistant lithium-ion battery device outer packaging materials.

Description of drawings

Fig. 1 is a schematic diagram of the structure of the application:

The markings in the attached drawings are:

1 is the outer substrate resin layer;

2 is the outer adhesive layer;

3 is the coloring layer;

4 is the corrosion-resistant layer;

5 is the middle metal layer;

6 is the corrosion-resistant layer;

7 is the inner adhesive layer;

8 is a thermal fusion resin layer;

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

Outer substrate resin layer:

In the present invention, the purpose of providing the outer base resin layer is to enable it to function as a base material for lithium ion battery packaging materials. The outer base resin layer is located on the outer layer side of the lithium ion battery packaging material.

The raw material for forming the outer base resin layer is not particularly limited as long as it has at least insulating properties as a function of the base material. For example, it can be made of resin, and additives can also be added to the resin.

There are many methods for making the resin layer of the outer base material. For example, a resin film may be directly formed from a resin, or a coated resin may be used. The resin film may be an unstretched film or a stretched film. The stretched film may be a uniaxially stretched film or a biaxially stretched film, and is preferably a biaxially stretched film. As the production method of the biaxially stretched film, there are, for example, a stepwise biaxial stretching method, a blown film method, and a simultaneous stretching method. As the resin coating method, for example, a roll coating method, a dimple coating method, an extrusion coating method, or the like.

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 phenolic resin, or modified products of these resins. In addition, the resin forming the resin layer of the outer base material may be a copolymer of these resins, may be a modified product of the copolymer, or may be a mixture of these resins.

Among the resins that form the resin layer of the outer base material, polyester and polyamide mentioned above are preferable.

Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, Copolyester etc. Moreover, as a copolyester, the copolyester etc. which have ethylene terephthalate as a main repeating unit are mentioned. Specifically, the copolymer polyester obtained by polymerizing ethylene terephthalate as the main body of the repeating unit and ethylene isophthalate (hereinafter referred to as copolyester (terephthalate) / isophthalate)), copolyester (terephthalate / adipate), copolyester (terephthalate / sodium isophthalate), copolyester (terephthalate dicarboxylate/phenyl-dicarboxylate), copolyester (terephthalate/decane dicarboxylate), etc. These polyesters may be used alone or in combination of two or more.

In addition, examples of polyamides specifically include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; Nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I means isophthalic acid, t means terephthalic acid) and other hexamethylenediamine-isophthalic acid-terephthalic acid structural units of isophthalic acid Aromatic polyamides such as copolyamide and polyamide MXD6 (polyamide PACM6 (polybis(4-aminocyclohexyl)methane azide amide). These polyamides may be used alone or in combination of two or more.

The outer substrate resin layer preferably contains at least one of polyester film, polyamide film and polyolefin film; preferably contains at least one of stretched polyester film and stretched polyamide film and stretched polyolefin film; further Preferably at least one of stretched polyethylene terephthalate film, stretched polybutylene terephthalate film, stretched nylon film, stretched polypropylene film; At least one of ethylene terephthalate film, biaxially oriented polybutylene terephthalate film, biaxially oriented nylon film, and biaxially oriented polypropylene film.

The outer base resin layer may be a single layer, or may be composed of two or more layers. When the outer base resin layer consists of two 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 to form two or more layers. In addition, the resin composite film formed by co-extruding the resin to form two or more layers may be used as the outer base resin layer in an unstretched state, or may be used as the outer base resin layer after being uniaxially stretched or biaxially stretched. .

In the outer base resin layer, specific examples of a laminate of two or more resin films include a composite film of a polyester film and a nylon film, a nylon composite film of two or more layers, and a polyester composite film of two or more layers. wait. A laminate of a stretched nylon film and a stretched polyester film, a stretched nylon composite film of two or more layers, and a stretched polyester composite film of two or more layers are preferable. For example, when the outer substrate resin layer is used as a two-layer resin composite film, a composite film of a polyester resin film and a polyester resin film, a composite film of a polyamide resin film and a polyamide resin film, or a polyester resin film and a composite film of a polyamide resin film are preferred. A composite film of a polyamide resin film, more preferably a composite film of a polyethylene terephthalate film and a polyethylene terephthalate film, a polybutylene terephthalate film and a polyethylene terephthalate film A composite film of a butylene formate 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. In addition, the polyester resin is unlikely to change color when the electrolyte is attached to the surface. Therefore, when using a resin composite film with two or more outer base resin layers, it is preferable that the polyester resin film is located in the outermost layer of the outer base resin layer.

When the resin layer of the outer base material is a resin composite film of two or more layers, the resin films of two or more layers may also be composited by an adhesive. As a preferred adhesive, glue with the same composition as the outer layer adhesive can be used. In addition, the method of laminating two or more resin films is not particularly limited, and dry lamination, sandwich lamination, extrusion lamination, thermal lamination, etc. can be used, and dry lamination is preferred. When laminating by a dry lamination method, it is preferable to use a polyurethane adhesive as the adhesive for the outer layer. At this time, the thickness of the adhesive layer may be about 2-5 μm.

In addition, one or more of lubricants, flame retardants, anti-blocking agents, antioxidants, light stabilizers, tackifiers, antistatic agents and other additives can be added to the surface and inside of the outer substrate resin layer.

From the viewpoint of improving the formability of the lithium ion battery packaging material, it is preferable to form-coat the lubricant on the surface of the outer base resin layer. The lubricant is not particularly limited, but amide-based lubricants are preferred. Amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylol amides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid amides and aromatic bisamides. Taking saturated fatty acid amide as an example, lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, etc. can be used. Examples of unsaturated fatty acid amides include oleic acid amide, erucic acid amide, and the like. Substituted amides include N-oleyl palmitamide, N-stearamide, N-stearamide, N-oleyl stearamide, and N-stearamide. In addition, methylolamide includes methylolstearic acid amide and the like. Saturated fatty acid bisamides include methylenebisstearamide, ethylenebiscaprylamide, ethylenebislauricamide, ethylenebisstearamide, ethylenebishydroxystearamide, ethylene Hexamethylene bisbehenamide and hexamethylene bis-behenamide, hexamethylene hydroxystearamide, n,n'-distearyl adipamide, n , n'-distearyl sebacic acid amide, etc. Unsaturated fatty acid bisamides include ethylene bisoleamide, ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, n,n'-dioleyl adipamide and n,n'-dioleyl decane acid amide. Fatty acid ester amides include stearamidoethyl stearate and the like. In addition, aromatic bisamides include m-xylyl bisstearic acid amide, m-xylyl bishydroxystearic acid amide, n,n'-distearyl isophthalic acid amide, and the like. A lubricant may be used alone or in combination of two or more.

When there is a lubricant on the surface of the outer base resin layer, the coating amount is not particularly limited, but it is preferably about 3 mg/m ² or more, more preferably about 4-30 mg/m ² .

The lubricant existing on the surface of the outer base resin layer may be the lubricant exuded from the base resin layer containing the lubricant, or the lubricant may be coated on 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 material. It is preferably about 3-50 μm, more preferably about 10-35 μm. When the outer base resin layer is a resin composite film of two or more layers, the thickness of the resin film constituting each layer is preferably about 2 to 30 μm.

Outer adhesive layer:

In the lithium ion battery packaging material of the present invention, when the outer base material resin layer and the intermediate metal layer are combined, an outer layer adhesive layer is provided. The outer adhesive layer is a layer formed for the purpose of improving, for example, the adhesiveness between the outer base resin layer and the intermediate metal layer.

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 to form the outer adhesive layer is not limited. For example, it may be a two-component curing adhesive (two-component adhesive), or a one-component curing adhesive (one-component adhesive). contact agent). And the adhesive used when forming the outer adhesive layer may be any one of chemical reaction type, solvent volatilization type, hot melt type, hot press type and the like. In addition, the outer adhesive layer may be a single layer or multiple layers.

The outer adhesive layer is a two-component polyurethane adhesive formed with polyester polyol and polyurethane-modified polyol as the main diol, and aromatic or aliphatic isocyanate as the curing agent. The curing agent can be selected according to the functional groups of the adhesive components, such as multifunctional epoxy resins, polymers containing methanesulfonic acid, polyamine resins, inorganic acids, and the like. In addition, the main agents used in the outer adhesive layer include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene isophthalate, copolymer Polyester resin such as polyester; polyether resin; polyurethane resin; epoxy resin; phenolic resin; polyamide resin such as nylon 6, nylon 66, nylon 12, and copolyamide; Polyolefin-based resins such as olefins and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; polyimide resins; polycarbonate; amino resins such as urea resins and melamine resins; chlorine Butadiene rubber, nitrile rubber, styrene-butadiene rubber and other rubber; silicone resin, etc. These adhesive components may be used alone or in combination of two or more.

The more preferred combination of the outer adhesive layer in the present invention is one or two kinds of two or more polyesters, polyurethane-modified polyesters and isocyanate. Isocyanates are not particularly defined as compounds having two or more isocyanate groups in the molecule. For example, one or two polymers such as isophorone diisocyanate (IPDI), toluene diisocyanate (TDI), diphenylmethane-4,4'-diisocyanate (MDI), 1,6-hexamethylene diisocyanate above mixture.

In addition, as long as the outer adhesive layer does not interfere with the adhesiveness, other components are allowed to be added, and may contain colorants, thermoplastic elastomers, tackifiers, fillers, and the like. When the outer adhesive layer contains a coloring agent, the lithium ion battery packaging material can be colored. As the colorant, colorants such as pigments and dyes can be used. In addition, one type of coloring agent may be used, and two or more types may be mixed and used.

The type of pigment is not particularly limited as long as it is within a range that does not impair the adhesiveness of the outer adhesive layer. As organic pigments, for example, pigments such as azo-based, phthalocyanine-based, quinacridone-based, anthraquinone-based, dioxazine-based, indothioindigo-based, perylene-based, and isoindoline-based pigments can be used; as inorganic pigments, Carbon black-based, titanium oxide-based, cadmium-based, lead-based, and isoindoline-based pigments can be used. 7. Among the colorants, for example, carbon black is preferable 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 it can be selected from about 0.05 to 5 μm, preferably about 0.08 to 2 μm. In addition, the average particle diameter of a pigment is the median diameter measured with the laser diffraction/scattering type 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, but it 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 it can bond the outer base material resin layer and the intermediate metal layer. As a lower limit, for example, it can be more than about 1 μm or more than about 2 μm, and as an upper limit, it can be about 10 μm or less or about 2 μm. 5 micrometers or less, about 1-10 micrometers are mentioned as a preferable range, More preferably, about 1-5 micrometers are mentioned.

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 material resin layer and the outer adhesive layer. In addition, a colored layer may be provided on the outer side of the outer base resin layer. By providing a colored layer, the lithium ion battery packaging material can be colored.

The colored layer can be formed, for example, by applying an 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, colorants such as pigments and dyes can be used. In addition, only one type of coloring agent may be used, or two or more types may be used in combination.

As specific examples of the colorant contained in the colored layer, reference may be made to the examples described for the outer adhesive layer.

Middle metal layer:

In the outer packaging material for lithium ion batteries, the intermediate metal layer is a barrier layer capable of at least suppressing the intrusion of water.

The metal material used as the intermediate metal layer can be specifically aluminum alloy, stainless steel, titanium steel, nickel-plated iron plate, etc., and when used as a metal foil, it can be one or more layers. It is preferable to contain at least one of aluminum alloy foil, nickel-plated iron plate, and stainless steel foil.

Generally, the selection of aluminum alloy foil is as follows. From the viewpoint of improving the formability of packaging materials for lithium-ion batteries, it is more preferable to use soft aluminum alloy foil composed of annealed aluminum alloy or the like to further improve formability. From the viewpoint of aluminum alloy foil is preferably iron-containing aluminum alloy foil. Silica, magnesium, and the like may be added as required for resistance to electrolytic solutions and the like.

Examples of the stainless steel foil include austenitic, ferritic, austenitic-ferritic, martensitic, and precipitation-hardened stainless steel foils. From the viewpoint of providing a lithium ion battery packaging material with better formability, the stainless steel foil is preferably made of austenitic stainless steel.

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

When the intermediate metal layer is a metal foil, it only needs to be thick enough to at least function as an intermediate metal layer that suppresses intrusion of water, 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, more preferably about 50 μm or less.

In addition, in the past, after the addition of alloy components, the alloy components were precipitated on the surface of the intermediate metal layer, or the volatility of the rolling oil was affected in the annealing process performed after the rolling process. Therefore, in the adjustment of the alloy composition, the management of the surface cleanliness becomes very important. The cleanliness of the surface can be managed either by wettability with a wetting reagent test or by contact angle. As an index of wettability, it is grade D or higher, preferably grade B. In addition, as an indicator of the contact angle, when tested with pure water, the contact angle is 25° or less, preferably 20° or less, more preferably 15° or less. If the wettability is lower than class D, or if the contact angle exceeds 25°, the reactivity with the anticorrosion layer described later or initial adhesion will deteriorate. If the reactivity deteriorates, the reaction between the anticorrosion layer and the intermediate metal layer becomes insufficient, and the permeation resistance to the electrolyte solution as the battery content and the resistance to hydrogen fluoride generated in the reaction of the electrolyte and water decrease. As time goes by, the adhesion of the anti-corrosion layer to the middle metal layer decreases, the anti-corrosion layer dissolves, and the middle metal layer and the anti-corrosion layer may peel off, thereby shortening the life of the battery. In addition, the same situation occurs when the initial adhesion between the anti-corrosion layer and the intermediate metal layer deteriorates. The present invention can suppress alloy precipitation from the intermediate metal layer by adjusting the alloy composition and keeping the ratio of the alloy within a certain range. In addition, in the annealing step during rolling, the management of temperature and time conditions can be facilitated.

The test method for the surface wettability of the intermediate metal layer can be used in "National Standard GB/T225638.5-2016 of the People's Republic of China, Aluminum Foil Test Method, Part 5: Wettability Test". The test method for the contact angle of the intermediate metal layer can be used in "National Standard GB/T22638.9-2008 of the People's Republic of China, Aluminum Foil Test Method Part 9: Determination of Hydrophilicity"

Anti-corrosion layer:

In the packaging materials for lithium-ion batteries, the anti-corrosion layer is to prevent the hydrogen fluoride generated by the reaction of the electrolyte and water from corroding the surface of the intermediate metal layer, prevent the separation between the intermediate metal layer and the internal thermal fusion resin layer, and maintain the uniformity of the surface of the intermediate metal layer. The change of adhesiveness (wettability) is small, and it has the effect of preventing delamination between the intermediate metal layer and the inner heat fusion resin layer in the metal composite film. Preferably, an anti-corrosion solution is applied to at least the intermediate metal layer opposite to the resin side of the outer base material to form an anti-corrosion layer, preferably on both sides of the intermediate metal layer. An anti-corrosion layer is formed on the intermediate metal layer in contact with the resin layer of the outer base material, which can stabilize the surface uniformity of the intermediate metal layer and reduce the change of adhesion (wettability). There is an anti-delamination effect between the outer substrate resin layer and the middle metal layer of the film.

As the anticorrosion layer formed by the chemical conversion treatment, various anticorrosion solutions are known, mainly containing phosphate, nitric acid, chromate, fluoride, rare earth oxide and the like.

The chemical conversion treatment using phosphate and chromate mainly includes, for example, chromium chromate treatment, chromium phosphate treatment, phosphoric acid-chromate treatment, chromate treatment, etc. As the chromium compound used in these treatments, there may be listed Chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium diphosphate, chromium acetate, chromium chloride, chromium sulfate. Chromate treatment methods mainly include etching chromate treatment, electrolytic chromate treatment, coating type chromate treatment, etc., but coating type chromate treatment is preferred. In this coating-type chromate treatment, phosphoric acid such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, Zn (submetallic lead) phosphate, etc. Metal salt and the mixture of these metal salts as the main component of the treatment liquid, or the treatment liquid of the non-metallic phosphate and the mixture of these non-metal salts as the main component, mixed with synthetic resin as the treatment liquid, by roller coating method, gravure printing Coating and drying are performed by known coating methods such as dipping and dipping. Various solvents such as water, alcohol-based solvents, hydrocarbon-based solvents, ketone-based solvents, ester-based compound-based solvents, and ether-based solvents can be used for the treatment liquid, but water is preferred. In addition, as the resin component used therein, a water-soluble polymer such as aminated phenol or polyacrylic resin can be selected.

As an example of an anti-corrosion layer, the particulate matter dispersed in phosphoric acid, such as aluminum oxide, titanium oxide, cerium oxide, tin oxide, and precipitated barium sulfate, is coated on the surface of the intermediate metal layer. Anti-corrosion layer formed by sintering.

Other examples of the anti-corrosion layer mainly include thin films obtained by coating type anti-corrosion treatment containing at least one selected from oxide sols of rare earth elements, anionic polymers and cationic polymers. an ingredient. The coating agent may contain phosphoric acid, phosphate, and a crosslinking agent for crosslinking the polymer. In the rare earth element oxide sol, fine particles of the rare earth element oxide (for example, particles with an average particle diameter of 100 nm or less) are dispersed in a liquid dispersion medium. The rare earth element oxide mainly contains cerium oxide, yttrium oxide, neodymium oxide, lanthanum oxide, etc., and cerium oxide is preferable from the viewpoint of further improving adhesion. The rare earth element oxide contained in the anticorrosion 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, alcohol solvents, hydrocarbon solvents, ketone solvents, ester compound solvents, and ether solvents can be used, and water is preferable. As a cationic polymer, it mainly includes polyethylene pipe imine, a complex ionic polymer complex formed by a polymer having polyethylene pipe imine and carboxylic acid, and a primary polymer of primary amines grafted and copolymerized on the main chain of acrylic. Aminegraf-toacrylic resin, polyacetic acid or its derivatives, aminated phenol, etc. Moreover, as an anionic polymer, the copolymer mainly containing poly (meth)acrylic acid or its salt, or (meth)acrylic acid and its salt as a main component is preferable. The crosslinking agent is preferably at least one of a compound having any one of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, and a silane coupling agent.

The anti-corrosion layer of the present invention is mainly made up of trivalent chromium compound, inorganic acid, fluoride, organic resin and water, controls the trivalent chromium compound, inorganic acid, fluoride, organic resin in the anti-corrosion layer coated on the intermediate metal layer The ratio is in the range of (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 anticorrosion solution is composed of at least one of chromium nitrate, chromium phosphate, chromium fluoride, and chromium chloride; the inorganic acid is composed of at least one of nitric acid and phosphoric acid; Composed of chromium; organic resin is composed of polyacrylic resin and polyvinyl alcohol; polyacrylic resin is polyacrylic acid, polymethyl acrylate, copolymer of acrylic acid and maleic acid, copolymer of acrylic acid and styrene and its One or more of derivatives such as sodium salt and ammonium salt, and the weight average molecular weight of the polyacrylic resin is 10,000-800,000.

The anticorrosion layer of the present invention is an aqueous solution mainly composed of trivalent chromium compounds, inorganic acids, organic resins, organic solvents, and titanates, and controls the trivalent chromium compounds, inorganic acids, and organic resins in the anticorrosion layer formed on the intermediate metal layer. , The ratio of titanate is in (25-38):(1-8):(10-12):(0-5). Wherein, the ratio of the trivalent chromium compound to the organic resin should be controlled within the range of (2-4):1.

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

The anticorrosion layer of the present invention is mainly composed of resin containing aminated phenolic polymer, trivalent chromium compound and phosphorus compound, and the aminated phenolic polymer, trivalent chromium compound in the anticorrosive layer coated on the aluminum alloy foil layer The proportion of the phosphorus compound is about 1 to 200 mg per m2 of the aminated phenolic polymer of the resin film layer, preferably controlled at about 0.5 to 50 mg for the trivalent chromium compound in terms of chromium, and about 0.5 mg for the phosphorus compound in terms of phosphorus. ~50mg range. As the aminated phenol polymer, the trivalent chromium compound, and the phosphorus compound, the compounds shown above can be used.

The anticorrosion layer of the present invention is mainly composed of at least two layers: a first layer formed of cerium oxide, phosphoric acid or phosphate formed on the side of the aluminum foil, and a layer formed of a cationic or anionic polymer formed on the side of the inner adhesive layer. . Preferably, the first layer contains 1 to 100 parts by mass of phosphoric acid or a phosphate salt with respect to 100 parts by mass of acid value cerium. As the phosphate, cationic or anionic polymer, those shown above can be used.

Examples of the fluoride include hydrofluoric acid, chromium fluoride, magnesium fluoride, elemental iron fluoride, cobalt fluoride, nickel fluoride, ammonium fluoride, titanium fluoride and its complex, zirconium fluoride salt, or Its complexes, magnesium fluoride, ammonium bifluoride, etc. In the present invention, chromium fluoride is preferred.

In the present invention, the titanate is not particularly limited, and titanous sulfate, titanium oxysulfate, ammonium titanium sulfate, titanium nitrate, ammonium titanium nitrate, titanium sulfate, fluorotitanic acid and its complexes, ethyl acetoacetate , trimethylethanol, melamine, n-butylhydroquinone or one or more of them.

As the polyacrylic resin, polyacrylic acid, acrylate-methacrylate copolymer, acrylic acid-maleic acid copolymer, acetate-styrene copolymer, or derivatives thereof such as sodium salt, ammonium salt, and amine salt are preferable. Derivatives of polyacrylic acid such as ammonium salts, sodium salts or amine salts of polyacrylic acid are particularly preferred. Here, polyacrylic acid refers to a polymer of acrylic acid. In addition, the polyacrylic resin is preferably a copolymer of acrylic acid and dicarboxylic acid or anhydrous dicarboxylic acid, and is also preferably an ammonium salt, sodium salt or amine salt of a copolymer of acrylic acid and carboxylic acid or disulfuric anhydride. The polyacrylic resin may be used alone or in combination of two or more.

The weight average molecular weight of the polypropylene resin is preferably about 1,000 to 1,000,000, more preferably about 30,000 to 800,000. The larger the molecular weight, the higher the corrosion resistance, but the water solubility of the polyacrylic resin is low, and the anti-corrosion effect of the formulation is low. The corrosive liquid is unstable and the production lacks stability. In addition, the smaller the molecular weight, the lower the corrosion resistance. In the present invention, when the weight average molecular weight of the polyacrylic resin is 1,000 or more, durability is high, and when it is 1 million or less, production stability is good.

As the formation of the anti-corrosion layer, first, the intermediate metal layer is treated with alkali dipping method, electrolytic cleaning method, acid cleaning method, electrolytic acid cleaning method, oxygen activation method, heat treatment (annealing treatment) during rolling, etc. At least the inner thermal bonding resin layer is degreased. Secondly, using the anti-corrosion solution of the present invention, it is applied on the surface of the intermediate metal layer by means of bar coating, roll coating, gravure coating, dipping, etc., and the high-temperature chemical reaction acts on the surface of the intermediate metal layer. The layer is heat-treated at a high temperature of 130-200°C for 0.5-5min to form an anti-corrosion layer.

The thickness of the anticorrosion layer is not particularly limited, but is preferably 1 nm to 3.0 μm, more preferably 1 nm to 1.5 μm, from the viewpoint of adhesion between the intermediate metal layer and the hot-melt resin layer. In addition, the amount of chromium in the anti-corrosion layer is between 8 mg/㎡ and 50 mg/㎡, preferably 10 mg/㎡ and 30 mg/㎡.

Inner Adhesive Layer:

In the lithium ion battery packaging material of the present invention, the inner adhesive layer is an intermediate layer provided for firmly bonding the intermediate metal layer and the inner heat-sealing layer.

The inner adhesive layer is formed of a resin capable of bonding the intermediate metal layer and the inner heat-sealing layer. As the resin used to form the inner adhesive layer. The above-mentioned internal heat welding resin layer can use polyolefin, cyclic polyolefin, etc., and can also use carboxylic acid-modified polyolefin, carboxylic acid-modified cyclic polyolefin, methacrylic acid-modified polyolefin, acrylic-modified polyolefin, croton, etc. Modified polyolefin-based resins such as acid-modified polyolefin and imide-modified polyolefin. From the viewpoint of enhancing the adhesiveness between the intermediate metal layer and the inner heat-sealing 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, and the analysis method is not particularly limited. The polyolefin and its modified resin used in the adhesive of the inner layer may be the same as the resin used in the inner heat-sealing resin layer, which is a polypropylene resin or a copolymer of propylene and ethylene.

From the perspective of long-term use stability of packaging materials for lithium-ion batteries, the inner adhesive layer can also be a resin combination containing acid-modified polyolefin and a curing agent. As the acid-modified polyolefin, maleic anhydride- or acrylic-modified polyolefin is particularly preferable.

The curing agent is not particularly limited as long as it cures the acid-modified polyolefin. Curing agents such as epoxy-based curing agents, polyfunctional isocyanate-based curing agents, carbodiimide-based curing agents, and oxazoline-based curing agents can be used.

The epoxy-based curing agent is not particularly limited as long as it is a compound having at least one epoxy group. For example, epoxy resins such as bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, novolak 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 two or more isocyanate groups in the molecule. For example, the polymerized or added components of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) or the above Reactants of class mixtures with other polymers.

The carbodiimide-based curing agent is not particularly limited as long as it is a compound having at least one carbodiimide group (—N=C=N—) in the molecule. A polycarbodiimide compound having at least two or more carbodiimide groups is preferable.

The oxazoline-based curing agent is not particularly limited as long as it is a compound having an oxazoline skeleton.

From the viewpoint of improving the adhesiveness between the inner adhesive layer and the inner heat-sealing layer, etc., the curing agent may be composed of two or more compounds.

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

For the inner layer adhesive layer, when the intermediate metal layer and the inner thermally welded resin layer are combined, a solution-type inner-layer adhesive layer method or a hot-melt-type inner-layer adhesive resin layer method may be used.

The main components of the inner adhesive layer of the present invention are denatured polyolefin resin, polyolefin resin, block copolymerized polypropylene resin (B-PP) with polypropylene (PP) content exceeding 50%, random copolymerized polypropylene resin (R-PP) ), one of the same polypropylene resin (H-PP) is a single layer or two or more film layers composed of two or more mixtures.

Polypropylene has the property of swelling but not dissolving when the electrolyte is infiltrated. When the content is less than 50%, other added ingredients are affected by the electrolyte, and the possibility of swelling and dissolution becomes high, and the inner adhesive layer dissolves in the electrolyte during long-term storage, and the middle metal layer and the inner thermal bonding layer cannot be maintained. Strength of.

The inner adhesive layer of the present invention uses acid-modified polyolefin resin as the main agent, and one or more of isocyanate, epoxy resin, oxyphospholipids, or amine compounds as hardeners, and is mixed with water, ethanol, isocyanate, etc. After dissolving at least one or two or more solvents such as propanol, ethyl acetate, methyl ethyl ketone, and toluene methylcyclohexane, they are uniformly placed on the metal surface that has undergone anti-corrosion treatment, and the solvent is evaporated after heating, so that The thickness of the inner adhesive layer achieves the desired effect.

The inner layer adhesive layer of the present invention is preferably about 1-10 μm, more preferably 1-5 μm. When the thickness is less than 1 μm, the thickness becomes thinner, the adhesive force between the intermediate metal layer and the inner heat-welded layer decreases, and adhesiveness becomes a problem. When the thickness exceeds 10 μm, there is no problem with the adhesion, but when the curing agent reacts, a hard resin layer is formed, the bending resistance is deteriorated, the flexibility of the metal composite film is reduced, and cracks may occur when bending. The metal layer and the inner heat weld layer sometimes peel off. The preferred curing agent of the present invention contains more than 50% of a mixture of isocyanurate derivatives of pentamethylene diisocyanate (PDI), or a mixture of isocyanurate derivatives of pentamethylene diisocyanate (PDI) and pentamethylene diisocyanate (PDI). The allophanate of methylene diisocyanate, preferably the amine compound is one or more mixtures of triethylamine and dimethylethanolamine. Among them, the functional group degree of pentamethylene diisocyanate is between 3.0 and 4.5.

When pentamethylene diisocyanate (PDI) isocyanurate derivatives, or pentamethylene diisocyanate (PDI) isocyanurate derivatives and pentamethylene diisocyanate allophanate ( When the content of the allophanate) derivative is less than 50%, the electrolyte resistance and acid resistance of the inner adhesive layer after curing become lower, the inner adhesive layer is easily dissolved, and the adhesion with the passivation layer or the inner heat-sealing layer becomes weaker. Connectivity deteriorates.

In addition, if the functionality of pentamethylene diisocyanate is less than 3, many linear reaction products will be produced. The linear reaction products are likely to be decomposed due to the penetration of the electrolyte and the generation of hydrogen fluoride acid. In addition, when the degree of functional group exceeds 4.5, there are few linear reactive components, and there are many reaction products in a densely packed three-dimensional structure. When the honey-like structure is formed, the internal stress of the adhesive bond layer increases, and the peel strength between the intermediate metal layer and the heat-sealing layer tends to decrease.

Anhydrous maleic acid, linolenic acid, methacrylic acid, acrylic acid, succinic acid, etc. are the acidic denaturants of the acid-denatured polypropylene used in the inner adhesive layer of the present invention. In addition, the melting point of the acid-modified polypropylene resin is between 60-97° C., preferably between 75-90° C., and the weight average molecular weight is between 6,000-80,000. In addition, the acid value of the inner layer adhesive used for the inner adhesive layer is 0.5-5.0 mgKOH/g, preferably 1.0-3.0 mgKOH/g. If the melting point is lower than 60° C., the heat resistance is low, and the intermediate metal layer and the internal heat fusion resin layer may be peeled off at high temperature. In addition, if it exceeds 97°C, the heat resistance is good, but when it reacts with the curing agent, a hard resin layer is formed. Due to poor flexibility, the flexibility of the metal composite film decreases, cracks occur when bent, and sometimes the middle metal layer and the inner heat are welded together. Layers peeled off. When the weight-average molecular weight is less than 6000, the fluidity of the resin is high when heated, the thickness is significantly thinner when heat-sealed, the adhesion strength of the intermediate metal layer and the inner heat-welded layer (in the case of a curing agent reaction) is reduced, and the sealing performance is problematic. When the weight-average molecular weight exceeds 80,000, the middle metal layer and the inner heat-welding layer (in the case of adding a curing agent) form a hard resin layer, the bending resistance becomes poor, the flexibility of the metal composite film decreases, or breaks to produce cracks, the middle The metal layer and the inner heat weld layer will peel off. When the acid value of the acid-modified polyolefin resin is less than 0.5 mgKOH/g, the curing reaction with the curing agent is less, and the adhesiveness between the intermediate metal layer and the inner thermal fusion layer is unstable. When the acid value exceeds 5.0mgKOH/g, the curing reaction between the curing agent and the acid-modified polyolefin resin is too high, a hard resin layer is formed, the bending resistance is deteriorated, the flexibility of the metal composite film is reduced, cracks are generated when bending, and the intermediate metal Layers and inner heat weld layers sometimes peel off.

Inner thermal welding layer:

In the lithium ion battery outer packaging material of the present invention, the inner heat-sealing layer corresponds to the innermost layer, and is a layer (heat-sealing layer) that performs the function of heat-sealing the heat-sealing resin layers to seal the battery element when the battery is assembled.

The resin constituting the inner heat-sealing layer is mainly heat-weldable, and is not particularly limited, and resins containing polyolefin main chains such as polyolefins and acid-modified polyolefins are preferred.

As polyolefins, specifically, polyethylene-α-olefin copolymers such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; homopolypropylene, polypropylene block Polypropylene such as copolymers (such as block copolymers of propylene and ethylene), random copolymers of polypropylene (such as random copolymers of propylene and ethylene); propylene-α-olefin copolymers; ethylene-butene-propylene terpolymers, etc. Among them, polypropylene is preferable. The polyolefin resin used as a copolymer may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

Acid-modified polyolefins are polymers modified by block polymerization or graft polymerization of polyolefins with acid components. As the acid-modified polyolefin, a copolymer obtained by copolymerizing a polar molecule such as the above-mentioned polyacrylic acid or methacrylic acid with the above-mentioned polyolefin can also be used. In addition, as the acid component used in the acid modification, carboxylic acids or sulfonic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride, and their anhydrides can be used, preferably acrylic acid or maleic acid. Toric acid and its anhydrides.

The inner heat-sealing layer may be composed of only one type of resin, or may be composed of two or more types of resins in combination. In addition, the inner heat-sealing layer may be only one layer, or may be composed of two or more layers, made of the same or different resins.

The inner heat-sealing layer may contain a slip agent or the like as necessary. When the inner thermally welded layer contains a slip agent, the formability of the lithium ion battery exterior material can be improved. The type of slip agent is not particularly limited, and can be selected and used within a known range. The slip agent may be used alone or in combination of two or more.

The slip agent is not particularly limited, but an amide-based slip agent is preferably used. The slip agent may be used alone or in combination of two or more.

When there is a slip agent on the surface of the inner heat welding layer, its content is not particularly limited, but from the viewpoint of improving the formability of electronic packaging materials, it is preferably 10-50 mg/m2, more preferably 15-40 mg/m2 .

The slip agent existing on the surface of the inner heat-sealing layer may be a slip agent exuded from the resin constituting the inner heat-sealing layer, or may be a slip agent coated on the surface of the inner heat-sealing layer.

The thickness of the inner thermally welded layer is not particularly limited, as long as the thermally weldable resin layers are thermally welded to each other to perform the function of sealing the battery element, it can be about 100 μm or less, more preferably about 25-80 μm.

The inner heat-sealing layer may also contain components such as an antioxidant as needed. The inner heat-sealing layer containing an antioxidant can suppress thermal deterioration during the manufacturing process. The type of antioxidant is not particularly limited, and can be selected and used within a known range. Antioxidants may be used alone or in combination of two or more.

The internal heat welding resin of the present invention is a single layer or a composite layer composed of one or more mixtures of acid-modified polyolefin resin, homogeneous polypropylene resin, block copolymerized polypropylene resin, random copolymerized polypropylene resin, and polyethylene resin.

The melting point of the resin used for the inner thermal welding layer is 120-162°C, more preferably 130-162°C, MFR (230°C) is 2-15g/10min, more preferably MFR (230°C) is 3-12g/10min A single layer or a multilayer composed of one or more than two mixtures has a thickness of 20-120 μm, more preferably 25-80 μm. In addition, when the inner thermally welded layer is a composite layer, the resin on the back side in contact with the intermediate metal layer has a thickness of 2 μm or more and a melting point of 130-152° C. When the melting point is below 120°C, the fluidity during heating is high, and the thickness becomes thin during pressure heat sealing, and the adhesion with the intermediate metal layer decreases. In addition, by applying pressure, the resin in the pressed part of the battery flows to the edge part that is not pressed, and cracks are generated due to the expansion and contraction of the battery and the external force of bending, and the electrolyte penetrates into the middle metal layer through the cracks, and the inside is thermally welded. The insulation resistance of the resin layer decreases, and leakage occurs, shortening the battery life. When the melting point exceeds 162°C, the crystallinity of the resin increases, the fluidity during pressure heat sealing is relatively reduced, and the heat resistance is improved. However, after the highly crystalline resin is heat-sealed, a hard and brittle resin layer is formed. Therefore, cracks are likely to occur in the resin layer due to expansion and contraction of the battery, external force of bending, etc., and long-term stable sealing properties cannot be obtained. When the resin MFR (230° C.) is less than 2 g/10 min, the fluidity of the resin during pressure heat sealing is low, and it is difficult to obtain stable sealing performance. When the MFR (230° C.) of the resin exceeds 15 g/10 min, the fluidity of the resin increases during pressure heat sealing, the thickness of the resin becomes thinner, and the sealing performance becomes unstable. In addition, by pressurization, the resin in the pressed part of the battery flows to the edge part that is not pressed, and cracks are generated due to the expansion and contraction of the battery and the external force of bending, and the electrolyte penetrates into the middle metal layer through the cracks, and the resin is thermally fused inside. The insulation resistance of the layer decreases, leakage occurs, and the battery life is shortened. When the thickness of the inner thermally welded layer is less than 20 μm, the thickness cannot sufficiently cover the variation in machining dimensions and conditions of the thermally welded device, so it is difficult to obtain a uniform thermally welded portion and stable sealing performance cannot be obtained. In addition, when the resin in the pressed part of the pressurized battery flows to the unpressed edge part, the thickness of the inner thermal welding layer becomes thinner, and the expansion and contraction of the battery and the external force of the bending process easily cause cracks, and the electrolyte penetrates into the middle through the cracks. The insulation resistance of the metal layer and the inner thermal welding layer is reduced, leakage occurs, and the battery life is shortened. When the thickness of the inner thermal welding layer exceeds 120 μm, the amount of water vapor permeation increases, and the moisture inside the battery increases, which reacts with the electrolyte to generate gas, which is prone to expansion, rupture, and leakage, and the battery life is reduced. Excess hydrogen fluoride corrodes to prevent corrosion The adhesion strength between the middle metal layer and the inner thermal welding layer of the treated metal layer is reduced, and problems such as electrolyte leakage are likely to occur.

Composite process:

Metal degreasing treatment: the surface wettability of the intermediate metal layer is 65 dyn/cm, preferably 70 dyn/cm or more, or the titration contact angle of distilled water is 15 degrees or less, preferably 10 degrees or less. If the wettability and surface water contact angle of the intermediate metal layer exceed the predetermined range, the rolling oil in the manufacturing stage may remain on the surface, which may cause formation of In the long-term storage of the battery, the interfacial adhesion formed between the intermediate metal layer and the inner heat-welded layer becomes poor, and there is a risk of falling off, which is prone to battery leakage. As preventive measures, heat treatment (annealing treatment) at 150°C or higher after rolling, plasma treatment method, and alkaline degreasing can be used to remove residual oil on the surface. The alkali degreasing method is to immerse the metal in the lye at 50-65°C, after a certain period of time, rinse it twice with deionized water, and dry it to get the metal without grease;

Anti-corrosion treatment of metal: coating anti-corrosion liquid on at least the side of the metal layer that is welded with the inner thermal fusion layer, and then heat-treating at high temperature for a certain period of time;

Coating and compounding of the outer layer adhesive: apply an outer layer adhesive dissolved in an organic solvent between the metal layer and the outer substrate resin layer, and heat it at a certain temperature for a period of time to make the organic solvent volatilize to form an outer adhesive layer. Then compound the middle metal layer and the outer substrate resin layer at a certain temperature and pressure, and cure for a period of time at a certain temperature to cure the outer adhesive layer to obtain an outer substrate resin layer, an outer adhesive layer and an intermediate metal layer. composed of composite resins. In the case where the outer layer adhesive is not used in 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 heat and pressure, through heat treatment, ultraviolet treatment, electron beam treatment, etc. By bonding the outer base resin layer and the intermediate metal layer, a composite resin layer composed of the outer base resin layer and the intermediate metal layer can be obtained.

Combination of internal thermal fusion resin: In the present invention, there are two ways of compounding the composite film with external base material resin and internal thermal fusion layer. Specifically, it can be divided into: a. Dry composite method: mainly apply the mixture of solution-type acid-modified polypropylene and aromatic isocyanate solution to the metal surface of the composite film that has been composited with the resin of the outer substrate, and dry it. Finally, the bonding layer is formed, and at a certain temperature, it is thermally compounded with the bonding surface of the heat-melting resin, and then it is cured. A composite finished product of the outer substrate resin layer/outer adhesive layer/intermediate metal layer/inner adhesive layer/inner thermal fusion layer is formed. The adhesive surface of the heat-melt resin film that is in contact with the inner adhesive layer is pre-corona treated; b. Thermal bonding method: dissolve the reactive acid-modified polypropylene with a melting point above 145°C into the solution, and then add epoxy Resin and methanesulfonic acid resin, the obtained bonding resin glue. Apply the mixed glue of reactive acid-modified polypropylene, epoxy resin and methanesulfonic acid resin as cross-linking agent evenly on the metal surface of the composite film that has been compounded with outer substrate resin and has been treated with anticorrosion, and form after drying The adhesive layer is thermally compounded with the corona-treated surface of the inner heat fusion resin, and further heat-treated at high temperature for a certain period of time, thus forming the outer substrate resin layer/outer adhesive layer/intermediate metal layer/inner adhesive layer/ Composite finished product with inner thermally welded layers.

Test Methods:

(1) Measurement of the melting point of the inner adhesive resin

Use a differential scanning calorimeter (Differential Scanning Calorimeter) to test, set the heating and cooling rate to 10°C/min, set four stages: 1, 25°C to 150°C, 2, 150°C to 25°C, 3. Heat up from 25°C to 150°C. 4. Cool down from 150°C to 25°C, measure the peak temperature of the second endothermic peak, and obtain its melting point.

(2) Molecular weight measurement of inner adhesive resin

Use high-temperature GPC to test the weight-average molecular weight Mw of the polymer resin;

Test conditions: test temperature: 150°C; mobile phase: trichlorobenzene (TCB); standard: polystyrene (PS); sample system: polyolefin samples, common samples PP and PE; test sample volume: 5mg;

Instrument model: PL‐GPC 220; Chromatographic column model: PLgel MIXED‐B LS 300x7.5mm; Detector: differential refractive index detector;

Sample preparation: Dissolve the sample completely in trichlorobenzene, filter it with a 0.22um organic filter membrane and test it directly on the machine, and read the test value of the weight average molecular weight Mw directly.

(3) Measurement of the acid value of the inner adhesive layer.

Use an organic solvent to dissolve the inner layer adhesive into a sample solution, then neutralize the titration sample solution with potassium hydroxide (KOH) or sodium hydroxide (NaOH) standard titration solution, and determine the titration end point by the corresponding color change of the indicator, and finally pass Calculate the acid value of the sample solution based on the volume of the standard titration solution consumed at the end point. Calculated as follows:

△V: Volume of KOH or NaOH consumed by titration (ml)

C: Molar concentration of KOH or NaOH standard solution (mol/L)

m: mass of resin (g)

(4) Initial peel strength test

Prepare the finished metal composite film into a straight strip with a sample size of 100*15mm. Use a tensile test device to perform a T-shaped peel measurement with the two peeling surfaces at 180° at a tensile speed of 50mm/min. 5 strips/group as a parallel test.

(5) Electrolyte resistance test of finished products

The finished sample of the metal composite film is directly soaked in dimethyl carbonate (DMC) containing 1mol/L LiPF ₆ : diethyl carbonate (DEC): ethylene carbonate (EC) with a ratio of 1:1:1. After soaking in a mixed solvent for 3 days at a temperature of 85°C, take it out, wash it with water for 15 minutes, wipe off the moisture on the surface of the sample, and measure the peel strength between the metal layer and the inner fusion resin layer according to the initial peel strength test method.

(6) Water-resistant electrolyte test of the finished product

The metal//internal fusion resin composite layer of the metal composite film finished sample is peeled off for a short period and soaked in dimethyl carbonate (DMC) containing 1mol/L LiPF6: diethyl carbonate (DEC): ethylene carbonate (EC) In a mixed solvent with a substance ratio of 1:1:1, add 1000PPM water accounting for the total mass of the electrolyte to the mixed solvent, soak it at 85°C for 3 days, take it out, wash it with water for 15 minutes, and keep the water dry. The peel strength between the metal layer and the inner fusion resin layer was measured according to the initial peel strength test method.

The specific embodiment of a kind of highly resistant electrolyte lithium-ion battery device packaging material and battery of the present invention is provided below:

Composite

The composite product is composed of outer substrate resin layer/outer adhesive layer/intermediate metal layer/inner adhesive layer/inner thermal welding layer.

The lamination method is as follows: Corona treatment is performed on the resin film of the outer substrate layer in contact with the outer adhesive layer. Specifically, one side of the metal foil (aluminum foil, nickel-plated iron foil or stainless steel foil, etc.) is coated with a two-component polyurethane adhesive (polyurethane-modified polyester polyol or polyester polyol and aromatic isocyanate compound) , forming an adhesive layer on the metal foil. After thermal lamination of the outer adhesive layer on the metal foil and the outer base material resin film, aging treatment is carried out at a temperature of 60° C. for 3 days to form an outer base material resin layer/outer adhesive layer/metal layer semi-finished product. Both sides of the metal layer are pre-corrosion treated.

Coat one side of the foil with an outer layer adhesive formulated as follows:

Amorphous polyester polyol with weight average molecular weight of 8000, Tg of 79°C and hydroxyl value of 16 mg KOH/g was mixed with amorphous polyester polyol of weight average molecular weight of 6500, Tg of -3°C and hydroxyl value of 10 mg KOH/g Non-reactive polyester polyols are mixed in a ratio of 10:5 by weight, and toluene diisocyanate is added to form a mixed outer layer bonding solution with an NCO/OH ratio of 21;

Both sides of the metal are pre-corrosion treated.

The anti-corrosion solution is evenly coated on both sides of the aluminum foil by a coating roller according to a certain ratio, and then baked at 190°C for ² minutes. , 6, 7 and Comparative Examples 1, 2, 3, the aluminum foil surface was coated with a Cr content of 15 mg/m ² .

Inner adhesive layer composite method

The obtained semi-finished product: outer substrate resin layer/outer adhesive layer/inner adhesive layer compounded on the metal surface of the middle metal layer. The inner adhesive layer is a two-component adhesive. Dry composite method: mainly apply the mixture of solvent-based acid-modified polypropylene and curing agent to the anti-corrosion treated metal surface of the composite film that has been composited with the outer substrate resin, and form a bonding layer after drying. Under the temperature of ℃, it is thermally compounded with the bonding surface of the hot-melt resin, and then it is cured at a temperature of 50°C for 7 days to form the outer substrate resin layer/outer adhesive layer/intermediate metal layer/inner adhesive layer/inner heat Composite products with welded layers. The bonding surface of the heat-melt resin film which is in contact with the inner adhesive layer is corona-treated in advance.

Inner thermal welding layer

The semi-finished packaging material that completes the outer substrate resin layer/outer adhesive layer/intermediate metal layer/inner adhesive layer is composited with the inner thermal fusion layer through dry lamination, and aged at 60°C for three days to the outside of the finished lithium-ion battery device Packaging Materials. The specific inner heat welding layer uses the following formula:

The internal heat welding resin is composed of three layers, and the side that is in contact with the inner adhesive layer is treated with corona, and its structure is:

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

Intermediate resin layer: by weight, 50% of the melting point is 162 ° C, MFR (230 ° C) is 2 g/10min block copolymer polypropylene; 20% of the melting point is 155 ° C, MFR (230 ° C) is 5 g/10 min 20% propylene-butene polymer elastomer with a melting point of 160°C, an MFR (230°C) of 9.5g/10min, and a density of 0.87g/cm ³ and 10% of MFR ( 230° C.) is a mixture layer formed of 3 g/10 min of non-crystalline propylene-based elastomer.

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

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

Example 1

A biaxially stretched nylon film with a material of 25 μm in the outer substrate layer is composited to a 35 μm thick 8021 series aluminum material with a surface wettability of 68 dyn/cm through an outer adhesive. Anti-corrosion treatment is carried out on both sides of the metal foil to form an anti-corrosion layer.

Anti-corrosion treatment on both sides of the metal foil. On the surface of the aluminum foil, 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 acid resin.

The inner thermal fusion layer is made by adding 100% by mass of pentamethylene diisocyanate to the modified polypropylene with a weight average molecular weight of 7000, a crystalline polypropylene content of 55%, a melting point of 65°C and an acid value of 2mgKOH/g. The internal adhesive is compounded to the semi-finished product to obtain the finished product. Wherein the functional group degree of pentamethylene diisocyanate used is 3.3.

Example 2

A biaxially stretched nylon film with a material of 25 μm in the outer substrate layer is composited to a 40 μm thick 8079 series aluminum material with a surface wettability of 70 dyn/cm through an outer layer adhesive. Both sides of the metal foil are anti-corrosion treated to form an anti-corrosion layer.

Anti-corrosion treatment on both sides of the metal foil. On the surface of the metal foil, the content ratio of trivalent chromium compound, inorganic acid and organic resin on the surface of the aluminum foil is 3:1:2. The trivalent chromium compound is chromium nitrate and chromium fluoride in a ratio of 1:1, the inorganic acid is phosphoric acid and nitric acid in a ratio of 1:1, and the organic resin is prepared by polyvinyl alcohol and polyacrylic resin in a ratio of 2:8.

The inner thermal fusion layer has a weight-average molecular weight of 24,000, wherein the crystalline polypropylene content is 75%, the melting point is 75°C, and the acid value is 4.6mgKOH/g Modified polypropylene, adding 100% by mass of pentamethylene diisocyanate As a curing agent, the inner adhesive obtained by both -NCO/-OH=3 is compounded on the semi-finished product to obtain the finished product. Wherein the functional group degree of pentamethylene diisocyanate used is 3.0.

Example 3

The material of the outer substrate layer is 25 μm bidirectional synchronously stretched nylon film, which is composited on the heat-treated 38 μm stainless steel foil through the outer layer adhesive, and the surface water contact angle is 15°. Both sides of the metal foil are anti-corrosion treated to form an anti-corrosion layer.

Anti-corrosion treatment on both sides of the metal foil. The content ratio of trivalent chromium compound, inorganic acid and 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-welding layer has a weight-average molecular weight of 68,000, wherein the crystalline polypropylene content is 85%, the melting point is 80° C., and the acid value is 3 mgKOH/g modified polypropylene, and 80% by mass of pentamethylene diisocyanate and 20% by mass of allophanate-modified pentamethylene diisocyanate is used as a curing agent to obtain an internal adhesive compounded on a semi-finished product to obtain a finished product. Wherein the functional group degree of pentamethylene diisocyanate is 3.5.

Example 4

The material of the outer substrate layer is a biaxially stretched nylon film of 25 μm, which is composited to a 50 μm thick steel plate with a surface degree of 72 dyn/cm and a nickel layer of 1 μm through the outer layer adhesive. Both sides of the metal foil are anti-corrosion treated to form an anti-corrosion layer.

Anti-corrosion treatment on both sides of the metal foil. The content ratio of trivalent chromium compound, inorganic acid and 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 acid resin.

The inner thermal fusion layer has a weight-average molecular weight of 78,000, wherein the crystalline polypropylene content is 75%, the melting point is 88°C, and the acid value is 1.4mgKOH/g. Add 75% of pentamethylene diisocyanate and 25% by mass of hexamethylene diisocyanate as an internal adhesive compounded on the semi-finished product to obtain a finished product. Among them, the functional group degree of pentamethylene diisocyanate is 3.3.

Example 5

The material of the outer substrate layer is a biaxially stretched nylon film of 25 μm, which is compounded to a 40 μm thick 8021 series aluminum material with a surface water contact angle of 15° through an outer layer adhesive. Both sides of the metal foil are anti-corrosion treated to form an anti-corrosion layer. Its anticorrosion layer is to form the layer that is made of 95% by weight cerium oxide (CeO2) and the aminopropyl trimethoxysilane of 5% by weight that thickness is 0.1 μ on both sides of the middle metal layer, and on the above-mentioned layer again A layer composed of a polyallylamine resin and an epichlorohydrin adduct of 1,6-hexanediol was formed with a thickness of 0.1 μ.

The inner thermal fusion layer has a weight-average molecular weight of 65,000, wherein the content of crystalline polypropylene is 95%, its melting point is 88°C, and its acid value is 1.4 mgKOH/g, and 75% by mass of modified pentamethylenediyl A mixture of isocyanate and 25% by mass of hexamethylene diisocyanate is used as a curing agent to prepare an internal adhesive with -NCO/-OH=3, which is compounded on a semi-finished product to obtain a finished product. Wherein the functional group degree of pentamethylene diisocyanate is 4.5.

Example 6

A biaxially stretched polynylon film with a material of 25 μm in the outer substrate layer is composited to an 80 μm thick 8079 series aluminum material with a surface wettability of 70 dyn/cm through an outer adhesive. Both sides of the metal foil are anti-corrosion treated to form an anti-corrosion layer. The content ratio of trivalent chromium compound, inorganic acid, fluoride and aminated phenolic 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 inner thermal welding layer is modified polypropylene with a weight-average molecular weight of 35,000, wherein the crystalline polypropylene content is 92%, the melting point is 75°C, and the acid value is 1.5mgKOH/g, and 60% by mass of pentamethylene di A mixture composed of isocyanate and 40% by mass of hexamethylene isocyanate is used as a curing agent to prepare an internal adhesive with -NCO/-OH=3, which is compounded on a semi-finished product to obtain a finished product. Wherein the functional group degree of pentamethylene diisocyanate is 3.8.

Example 7

The biaxially stretched nylon film with an outer substrate layer of 25 μm is composited to a 50 μm thick 8021 series aluminum foil with a surface water contact angle of 10° through an outer layer adhesive. Both sides of the metal foil are anti-corrosion treated to form an anti-corrosion layer.

Anti-corrosion treatment on both sides of the metal foil. The content ratio of trivalent chromium compound, inorganic acid and 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 at a ratio of 1:2, the inorganic acid is nitric acid, and the organic resin is polyacrylic acid resin.

The inner thermal fusion layer is modified polypropylene with a weight-average molecular weight of 78000, wherein the crystalline polypropylene content is 92%, the melting point is 92°C, and the acid value is 3mgKOH/g, and 80% by mass of pentamethylene diisocyanate is added. and a curing agent composed of 20% by mass of toluene diisocyanate (TDI) to prepare an internal adhesive with -NCO/-OH=3 and compound it on a semi-finished product to obtain a finished product. Wherein the functional group degree of pentamethylene diisocyanate is 3.3.

Comparing Examples 1, 3, 4, and 5, it is found that increasing the content of crystalline polypropylene resin in the adhesive layer resin improves the initial peel strength, indicating that a higher content of crystalline polypropylene resin can improve the internal thermal welding layer. Peel strength with intermediate metal layer.

Comparing Examples 3-6, it is found that the content of the mixture of pentamethylene diisocyanate or pentamethylene diisocyanate and allophanate thereof is improved, and its 3-day resistance to electrolyte test and 3-day addition of water resistance to electrolyte test The peel strength maintenance rate increased, indicating that increasing the content of pentamethylene diisocyanate can improve the electrolyte resistance of the inner heat-welding layer and the middle metal layer.

Comparing Examples 1, 2, 4, and 5, it is found that increasing the molecular weight of the inner adhesive layer resin finds that the peeling strength of the inner heat-welded layer and the middle metal layer gradually increases, indicating that increasing the molecular weight of the inner adhesive layer resin can improve the inner layer. The peel strength between the heat-welded layer and the intermediate metal layer.

Comparative example 1

The resin of the outer substrate layer is selected as 25 μm bidirectional synchronously stretched nylon film, and the outer layer adhesive is compounded on the 40 μm 8021 series aluminum foil with a surface water contact angle of 10° to obtain a semi-finished product. The surface of the aluminum foil is treated with an antiseptic solution. Anti-corrosion treatment is carried out on both sides of the metal foil to form an anti-corrosion layer

Anti-corrosion treatment on both sides of the metal foil. The content ratio of trivalent chromium compound, inorganic acid, fluoride and aminated phenolic 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 inner thermal fusion layer is made of modified polypropylene with a weight average molecular weight of 80,000, a crystalline polypropylene content of 30%, a melting point of 50°C, and an acid value of 3 mgKOH/g, and solidified with 100% by mass of pentamethylene diisocyanate The inner layer adhesive of -NCO/-OH=3 prepared by compounding the semi-finished product to make the finished product. Among them, the functional group degree of pentamethylene diisocyanate is 2.8.

Comparative example 2

The resin of the outer substrate layer is selected as 25 μm bidirectional synchronously stretched nylon film, and the outer layer adhesive is compounded on the 40 μm 8021 series aluminum foil with a surface water contact angle of 10° to obtain a semi-finished product. Both sides of the metal foil are anti-corrosion treated to form an anti-corrosion layer.

Anti-corrosion treatment on both sides of the metal foil. The content ratio of trivalent chromium compound, inorganic acid and 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 acid resin.

The inner thermal fusion layer is made of modified polypropylene with a weight-average molecular weight of 5600, wherein the crystalline polypropylene content is 95%, the melting point is 120°C, and the acid value is 0.3mgKOH/g, and 100% by mass of pentamethylene diisocyanate The inner layer adhesive of -NCO/-OH=3 prepared for the curing agent is compounded on the semi-finished product to obtain the finished product. Wherein the functional group degree of pentamethylene diisocyanate is 4.7.

Comparative example 3

Inner thermal fusion layer is by using weight-average molecular weight 78000, wherein crystalline polypropylene content is 92%, fusing point 88 ℃, the modified polypropylene of acid value 5.4mgKOH/g, with the toluene diisocyanate (TDI) of 70% mass parts and 30% by mass of the mixture of pentamethylene isocyanate is used as the curing agent, and the inner layer adhesive is compounded on the semi-finished product to obtain a finished product. Among them, the functional group degree of pentamethylene diisocyanate is 4.7.

Table 1 Evaluation results of the peel strength between the middle metal layer and the inner thermally welded layer

The above is the statistics of the evaluation results of the peel strength between the middle metal layer and the inner thermally 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 middle metal layer and the inner welded layer to the initial strength measured after resisting the electrolyte.

Compared with Comparative Example 1, the melting point of the inner layer adhesive is lower than 60°C, the content of crystalline polypropylene is lower than 50%, and the functional group degree of pentamethylene diisocyanate is 2.8. Although it has a good peel strength under the initial conditions, there was a significant decline in the 3-day electrolyte resistance test and the 3-day water-added electrolyte resistance test, and the maintenance rates were 75.3% and 60.5%, respectively.

Compared with Comparative Example 2, due to the higher melting point, the inner adhesive layer has a higher viscosity, which leads to the inability to form an inner adhesive layer stably and thus cannot obtain better peel strength in the initial situation; at the same time, because the inner adhesive used The functional group degree of pentamethylene diisocyanate is 4.7 and the molecular weight and acid value of the resin are low, which leads to a large drop in peel strength in the electrolyte resistance test and water resistance electrolyte test, and the maintenance rate is only 73% and 59% respectively .

Compared with Comparative Example 3, the amount of pentamethylene isocyanate added is less than 50%. Although the strength was higher at the initial stage due to the higher acid value, the adhesive layer after curing was easy to break, and the peel strength also dropped significantly in the 3-day electrolyte resistance test and the 3-day water-added electrolyte resistance test, respectively. Only 72% and 59%.

The above descriptions are only some specific embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection. The technical scope of the present invention is not limited to the content in the specification, but must be determined according to the scope of the claims.

Claims

An outer packaging material for an electrolyte-resistant lithium-ion battery device, characterized in that: it includes an outer substrate resin layer, an intermediate metal layer, an inner adhesive layer, and an inner heat-welding layer; the inner adhesive layer is made of acid-modified polypropylene The adhesive composed of resin and curing agent is formed; the acid-modified polypropylene resin is at least one of block copolymerized polypropylene, random copolymerized polypropylene and homopolypropylene with a crystalline polypropylene content greater than 50%.
The outer packaging material for electrolyte-resistant lithium-ion battery devices according to claim 1, wherein the acid modifier used in the acid-modified polypropylene resin is anhydrous maleic acid, maleic acid, methyl One of acrylic acid, acrylic acid, and succinic acid.
The outer packaging material for electrolyte-resistant lithium-ion battery devices according to claim 1, characterized in that: the melting point of the acid-modified polypropylene resin is between 60-97°C, and the weight-average molecular weight is between 6000-80000 .
The outer packaging material for electrolyte-resistant lithium-ion battery devices according to claim 3, characterized in that: the melting point of the acid-modified polypropylene resin is between 75-90°C.
The outer packaging material for an electrolyte-resistant lithium-ion battery device according to claim 1, wherein the inner layer adhesive used in the inner adhesive layer has an acid value of 0.5-5 mgKOH/g.
The outer packaging material for an electrolyte-resistant lithium-ion battery device according to claim 5, wherein the inner layer adhesive used in the inner layer adhesive layer has an acid value of 1-3 mgKOH/g.
The outer packaging material for electrolyte-resistant lithium-ion battery devices according to claim 1, wherein the curing agent is at least one of resins containing isocyanate components, epoxy resins, methanesulfonic acid resins, and amine compounds. A sort of.
The outer packaging material for electrolyte-resistant lithium-ion battery devices according to claim 7, wherein when the curing agent is a resin containing an isocyanate component, it is an isocyanate containing more than 50% of pentamethylene diisocyanate A mixture of derivatives, or an isocyanate mixture of isocyanate derivatives of pentamethylene diisocyanate and allophanate of pentamethylene diisocyanate; wherein the functional group of pentamethylene diisocyanate is between 3.0 and 4.5 .
The outer packaging material for an electrolyte-resistant lithium-ion battery device according to claim 1, wherein at least the side where the intermediate metal layer contacts the inner adhesive layer is treated with an anti-corrosion solution; in parts by mass, the anti-corrosion solution contains 19-60 parts of trivalent chromium compound, 3-60 parts of inorganic acid, 6-60 parts of organic resin, 0-10 parts of fluoride; the trivalent chromium compound is at least composed of a composition.
The outer packaging material for an electrolyte-resistant lithium-ion battery device according to claim 9, wherein the inorganic acid is at least one of nitric acid and phosphoric acid; the fluoride is at least chromium fluoride, A composition of aluminum fluoride; the organic resin is composed of polyacrylic resin and polyvinyl alcohol; the polyacrylic resin is a copolymer of polyacrylic acid, polymethyl acrylate, acrylic acid and maleic acid, acrylic acid One or more of the copolymer of styrene and its sodium salt and ammonium salt derivatives, and the weight average molecular weight of the polyacrylic resin is 10,000-800,000.
The outer packaging material for electrolyte-resistant lithium-ion battery devices according to claim 1, further comprising an outer anti-corrosion layer on the side where the intermediate metal layer is in contact with the outer base material resin layer.
A battery characterized by using the outer packaging material for an electrolyte-resistant lithium-ion battery device according to any one of claims 1 to 11.