Battery outer packaging material

Abstract

The application discloses a battery outer packaging material and belongs to the technical field of battery packaging. The battery outer packaging material comprises, from outside to inside, a substrate layer, an adhesive layer, a metal layer and a sealing layer; the substrate layer is a biaxial stretching polymer film with a thickness of 10-50 microns; the metal layer is a metal with a thickness of 10-100 microns; the sealing layer is a thermoplastic resin; and the adhesive layer comprises, by weight fraction, polyester polyol, comb copolymer and modified polyisocyanate curing agent. The comb copolymer prepared by copolymerization of unsaturated acrylic ester monomer and unsaturated polyether monomer reduces the difficulty of high-performance polyester polyol polycondensation synthesis, improves the water resistance and high temperature and high humidity resistance of the product. The battery outer packaging material prepared by the application has high peeling performance and forming performance, high product forming limit and good long-term stability, is suitable for harsh external environment and has wide application prospect.

Description

Technical Field

[0001] This invention relates to the technical field of battery packaging, specifically to battery outer packaging materials. Background Technology

[0002] In recent years, the production and sales of new energy vehicles have experienced explosive growth. As one of the main components of new energy vehicles, lithium-ion power batteries are receiving increasing attention for their safety and driving range. Currently, lithium-ion power batteries are mainly packaged in cylindrical and square shells, primarily made of aluminum alloy or steel. They are heavy and prone to explosion upon severe impact.

[0003] To address the aforementioned issues, lithium-ion pouch batteries have emerged, and their application rate is gradually increasing. Pouch battery packaging materials are primarily composite materials consisting of a thin metal layer and a polymer film. Their main structural components, from the outside in, can be divided into a substrate layer, an adhesive layer, a metal layer, and a sealing layer. The adhesive tightly bonds the substrate layer and the metal layer, and its performance directly affects important properties such as the molding limit and peel strength of the packaging material. Currently, the most widely used outer layer adhesives on the market are two-component curing polyurethane adhesives. The two components are a main agent and a curing agent, with the main agent primarily being a polyester polyol macromolecule. This polyester polyol is typically formed by the condensation polymerization of aromatic polyacids and aliphatic polyols. However, facing product demands for higher molding limits and peel strength, simply controlling the polyester polyol structure is insufficient to simultaneously meet these requirements. Furthermore, the condensation polymerization itself is difficult to control, and the introduction of rigid polyacids and long-chain aliphatic polyacids presents even greater challenges and difficulties to the reaction itself and the product structure. Considering the current safety of lithium batteries, the high temperature resistance of packaging materials is also receiving attention. The ester bonds of polyester polyols are prone to hydrolysis in high temperature and high humidity environments, which will lead to a decrease in the bonding strength of the outer adhesive layer, and thus the risk of delamination and cracking.

[0004] Therefore, there is a need for a battery packaging material with high adhesive layer bonding strength, higher molding limit, and applicability in high temperature and high humidity environments. Summary of the Invention

[0005] To address the existing technical problems, this invention provides a battery outer packaging material, comprising, from the outside in, a substrate layer, an adhesive layer, a metal layer, and a sealing layer;

[0006] The substrate layer is a biaxially stretched polymer film with a thickness of 10μm to 50μm;

[0007] The metal layer is a metal with a thickness of 10μm to 100μm;

[0008] The sealing layer is made of thermoplastic resin.

[0009] Preferably or optionally, the substrate layer is one or more of polyethylene terephthalate film, polybutylene terephthalate film, and polyamide film.

[0010] Preferably or optionally, the adhesive layer comprises, by weight, ~ parts polyester polyol, ~ parts comb copolymer, and ~ parts modified polyisocyanate curing agent.

[0011] Preferably or optionally, the polyester polyol contains a dicarboxylic acid component, wherein the dicarboxylic acid contains an aromatic diacid, which accounts for 60 mol% to 90 mol% of the dicarboxylic acid.

[0012] Preferably or optionally, the number average molecular weight of the polyester polyol is 6,000 to 30,000; the comb copolymer is a copolymer with a molecular weight of 1,000 to 6,000 obtained by copolymerizing unsaturated acrylate monomers and unsaturated polyether monomers.

[0013] Preferably or optionally, the unsaturated acrylate monomers include one or more of methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate; the unsaturated polyether monomers include one or more of allyl polyethylene glycol ether, isobutylene polyethylene glycol ether, isopentenyl polyethylene glycol ether, and ethylene glycol monovinyl polyethylene glycol ether.

[0014] Preferably or optionally, the modified polyisocyanate curing agent is a polyisocyanate treated with a chain extender, wherein the polyisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; and the chain extender is one of trimethylolpropane, methylpentane glycol, dimethylbutane glycol, ethylene glycol, and glycerol (GLY).

[0015] Preferably or optionally, the isocyanate group [NCO] of the modified polyisocyanate curing agent and the hydroxyl group [OH] of the polyester polyol and polycarboxylic acid comb copolymer have an equivalent ratio [NCO] / [OH] of 5 to 25, as measured by a molar concentration meter.

[0016] A battery, characterized in that, within the battery outer packaging material described in any one of the preceding claims, a battery element having at least a positive electrode, a negative electrode, and an electrolyte is housed.

[0017] Beneficial Effects: This invention provides a battery outer packaging material. During the adhesive preparation process, a comb-shaped copolymer, obtained by copolymerizing unsaturated acrylate monomers and unsaturated polyether monomers, is introduced. Through the mutual repulsion between the lipophilic acrylate segments and the hydrophilic polyether segments, the degree of molecular chain entanglement within the system is reduced, thereby simplifying the high-performance polyester polyol condensation polymerization and imparting higher peel and molding properties to the battery outer packaging material. Furthermore, the high salt resistance of the comb-shaped copolymer reduces the corrosive effect of battery electrolytes on the outer packaging material. In addition, the polyether segments in the comb-shaped copolymer structure, after cross-linking with an isocyanate curing agent, can improve the product's water resistance and high-temperature and high-humidity resistance, giving the battery outer packaging material longer-lasting stability and better performance in harsh environments such as high temperature and high humidity. This invention uses hot-melt resin to heat-fuse the sealing layer around the battery element for sealing and isolating the electrolyte. The invention also chemically treats the surface of the metal layer to further prevent corrosion from electrolytes and other substances. By selecting a biaxially stretched polymer film of appropriate thickness, the stress during bulging or deep drawing is reduced while ensuring strength, thereby improving formability. This invention controls the [NCO] / [OH] ratio to be between 5 and 25, at which the adhesive exhibits good bonding strength and mechanical properties. Too low a [NCO] / [OH] ratio leads to low peel strength, which is detrimental to the adhesion between the substrate layer and the metal layer, increasing the risk of detachment. Too high a [NCO] / [OH] ratio results in excessively high overall hardness of the adhesive layer, causing a decrease in the molding performance of the packaging material. The battery packaging material obtained by this invention possesses high peel and molding performance, a high molding limit, and good long-term stability, making it suitable for harsh external environments and showing broad application prospects. Detailed Implementation

[0018] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention.

[0019] The present invention will be further described below with reference to the embodiments. These embodiments are intended to explain the invention and should not be construed as limiting it. Where specific techniques and reaction conditions are not specified in the embodiments, they can be performed according to the techniques or conditions described in the literature or product instructions in the art. All reagents, instruments, or equipment without a specified manufacturer are commercially available.

[0020] Examples 1-5 below first describe the synthesis and preparation of the adhesive layer, which is mainly composed of a two-component solvent-based polyurethane adhesive. This adhesive comprises a main agent (component A) and a curing agent (component B), wherein component A further includes a polyester polyol (A1) and a comb copolymer (A2). The synthesis details are discussed in the following examples.

[0021] Example 1

[0022] I. Preparation of the adhesive layer:

[0023] The molar ratio of polyester polyol (A1) to comb copolymer (A2) was determined to be 1;

[0024] The A1 component polyester polyol is formed by high-temperature condensation polymerization of 99.67g isophthalic acid, 58.45g adipic acid, and 104.15g neopentyl glycol, wherein the aromatic diacid accounts for 60% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 6000.

[0025] Component A2 is prepared by free radical copolymerization of 86.08g of methyl acrylate and 250g of allyl polyethylene glycol ether with a number average molecular weight of 1000, wherein methyl acrylate accounts for 80% of the total molar content and the copolymer has a molecular weight of 10000.

[0026] Component B is a trimer formed by the reaction of isocyanate TDI and chain extender TMP, with a final [NCO] / [OH] ratio of 5.

[0027] After mixing A1, A2, and B evenly, adhesive 1 is prepared and used as the adhesive layer for the outer packaging material of the battery.

[0028] II. Production of battery packaging materials:

[0029] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating it with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Subsequently, the outer adhesive layer is coated on one side at a rate of 3 g / m². 2 After being treated in an 80°C oven, a 25μm biaxially stretched polyamide film (i.e., the substrate layer) was laminated onto the outer adhesive layer and then laminated using a hot roller. The film was aged at 60°C for 7 days. After aging, a 40μm acid-modified polyolefin (sealing layer) was laminated onto the inner layer of the aluminum foil and then treated at 180°C. The film was then cooled to room temperature to obtain battery packaging material 1.

[0030] Peel strength and molding performance were tested.

[0031] Example 2

[0032] I. Preparation of the adhesive layer:

[0033] The molar ratio of polyester polyol (A1) to comb copolymer (A2) was determined to be 2;

[0034] The A1 component polyester polyol is formed by high-temperature condensation polymerization of 116.13g isophthalic acid, 43.84g adipic acid, and 118.17g hexanediol, wherein the aromatic diacid accounts for 70% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 10000.

[0035] Component A2 is a free radical copolymer of 100.11g of ethyl acrylate and 500g of isobutylene-based polyethylene glycol ether with a number average molecular weight of 2000. Ethyl acrylate accounts for 80% of the total molecular weight, and the copolymer has a molecular weight of 15000.

[0036] Component B is a trimer formed by the reaction of isocyanate TDI and chain extender TMP, with a final [NCO] / [OH] ratio of 10.

[0037] After mixing A1, A2, and B evenly, adhesive 2 is prepared and used as the adhesive layer for the outer packaging material of the battery.

[0038] II. Production of battery packaging materials:

[0039] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating it with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Subsequently, the outer adhesive layer is coated on one side at a rate of 3 g / m². 2 After being treated in an 80°C oven, a 25μm biaxially stretched polyamide film (i.e., the substrate layer) was laminated onto the outer adhesive layer and then laminated using a hot roller. The film was aged at 60°C for 7 days. After aging, a 40μm acid-modified polyolefin (sealing layer) was laminated onto the inner layer of the aluminum foil and then treated at 180°C. The film was then cooled to room temperature to obtain battery packaging material 2.

[0040] Example 3

[0041] I. Preparation of the adhesive layer:

[0042] The molar ratio of polyester polyol (A1) to comb copolymer (A2) was determined to be 3;

[0043] The A1 component polyester polyol is formed by high-temperature condensation polymerization of 132.9g isophthalic acid, 29.22g adipic acid, and 118.17g hexanediol, wherein the aromatic diacid accounts for 80% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 15000.

[0044] Component A2 is a free radical copolymer of 100.16g of methyl methacrylate and 1285.71g of isopentenyl polyethylene glycol ether with a number average molecular weight of 3000. Methyl methacrylate accounts for 80% of the total molecular weight, and the copolymer has a molecular weight of 20000.

[0045] Component B is a trimer formed by the reaction of isocyanate MDI and chain extender TMP, with a final [NCO] / [OH] ratio of 15.

[0046] After mixing A1, A2, and B evenly, adhesive 1 is prepared and used as the adhesive layer for the outer packaging material of the battery.

[0047] II. Production of battery packaging materials:

[0048] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating it with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Subsequently, the outer adhesive layer is coated on one side at a rate of 3 g / m². 2 After being treated in an 80°C oven, a 25μm biaxially stretched polyamide film (i.e., the substrate layer) was laminated onto the outer adhesive layer and then laminated using a hot roller. The film was aged at 60°C for 7 days. After aging, a 40μm acid-modified polyolefin (sealing layer) was laminated onto the inner layer of the aluminum foil and then treated at 180°C. The film was then cooled to room temperature to obtain battery packaging material 1.

[0049] Example 4

[0050] I. Preparation of the adhesive layer:

[0051] The molar ratio of polyester polyol (A1) to comb copolymer (A2) was determined to be 4;

[0052] The A1 component polyester polyol is formed by high-temperature condensation polymerization of 149.51g isophthalic acid, 14.61g adipic acid, and 118.17g hexanediol, wherein the aromatic diacid accounts for 90% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 20,000.

[0053] Component A2 is a free radical copolymer of 114.14g of ethyl methacrylate and 1714.28g of ethylene glycol monovinyl polyethylene glycol ether with a number average molecular weight of 4000. Ethyl methacrylate accounts for 70% of the total molar content, and the copolymer has a molecular weight of 25000.

[0054] Component B is a trimer formed by the reaction of isocyanate MDI and chain extender GLY, with a final [NCO] / [OH] ratio of 15.

[0055] After mixing A1, A2, and B evenly, adhesive 4 is prepared and used as the adhesive layer for the outer packaging material of the battery.

[0056] II. Production of battery packaging materials:

[0057] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating it with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Subsequently, the outer adhesive layer is coated on one side at a rate of 3 g / m². 2 After being treated in an 80°C oven, a 25μm biaxially stretched polyamide film (i.e., the substrate layer) was laminated onto the outer adhesive layer and then laminated using a hot roller. The film was aged at 60°C for 7 days. After aging, a 40μm acid-modified polyolefin (sealing layer) was laminated onto the inner layer of the aluminum foil and then treated at 180°C. The film was then cooled to room temperature to obtain battery packaging material 1.

[0058] Example 5

[0059] I. Preparation of the adhesive layer:

[0060] The molar ratio of polyester polyol (A1) and comb copolymer (A2) was determined to be 5;

[0061] The A1 component polyester polyol is formed by high-temperature condensation polymerization of 99.67g isophthalic acid, 58.45g adipic acid, and 62.06g ethylene glycol, wherein the aromatic diacid accounts for 80% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 25,000.

[0062] Component A2 is a free radical copolymer of 142.19g butyl methacrylate and 3333.33g allyl polyethylene glycol ether with a number average molecular weight of 5000. The butyl methacrylate accounts for 60% of the total molecular weight, and the copolymer has a molecular weight of 30000.

[0063] Component B is a trimer formed by the reaction of isocyanate IPDI and chain extender GLY, with a final [NCO] / [OH] ratio of 20.

[0064] After mixing A1, A2, and B evenly, adhesive 5 is prepared and used as the adhesive layer for the outer packaging material of the battery.

[0065] II. Production of battery packaging materials:

[0066] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating it with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Subsequently, the outer adhesive layer is coated on one side at a rate of 3 g / m².2 After being treated in an 80°C oven, a 25μm biaxially stretched polyamide film (i.e., the substrate layer) was laminated onto the outer adhesive layer and then laminated using a hot roller. The film was aged at 60°C for 7 days. After aging, a 40μm acid-modified polyolefin (sealing layer) was laminated onto the inner layer of the aluminum foil and then treated at 180°C. The film was then cooled to room temperature to obtain battery packaging material 5.

[0067] Example 6

[0068] I. Preparation of the adhesive layer:

[0069] The molar ratio of polyester polyol (A1) to comb copolymer (A2) was determined to be 1;

[0070] The A1 component polyester polyol is formed by high-temperature condensation polymerization of 116.13g isophthalic acid, 43.84g adipic acid, and 76.1g propylene glycol, wherein the aromatic diacid accounts for 70% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 30,000.

[0071] Component A2 is a free radical copolymer of 142.19g butyl methacrylate and 4000g isobutylene-based polyethylene glycol ether with a number average molecular weight of 6000. The butyl methacrylate accounts for 60% of the total molar content, and the copolymer has a molecular weight of 30000.

[0072] Component B is a trimer formed by the reaction of isocyanate IPDI and chain extender GLY, with a final [NCO] / [OH] ratio of 25.

[0073] After mixing A1, A2, and B evenly, adhesive 6 is prepared and used as the adhesive layer for the outer packaging material of the battery.

[0074] II. Production of battery packaging materials:

[0075] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating it with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Subsequently, the outer adhesive layer is coated on one side at a rate of 3 g / m². 2 After being treated in an 80°C oven, a 25μm biaxially stretched polyamide film (i.e., the substrate layer) was laminated onto the outer adhesive layer and then laminated using a hot roller. The film was aged at 60°C for 7 days. After aging, a 40μm acid-modified polyolefin (sealing layer) was laminated onto the inner layer of the aluminum foil and then treated at 180°C. The film was then cooled to room temperature to obtain battery packaging material 6.

[0076] Comparative Example 1

[0077] I. Preparation of the adhesive layer:

[0078] The adhesive layer consists of a two-component solvent-based polyurethane adhesive, which is a mixture of a main agent (referred to as component A) and a curing agent (referred to as component B). Component A, polyester polyol, is formed by high-temperature condensation polymerization of 99.67g isophthalic acid, 58.45g adipic acid, and 104.15g neopentyl glycol, wherein the aromatic diacid accounts for 60% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 6000. Component B is a trimer formed by the reaction of isocyanate TDI and chain extender TMP, with a final [NCO] / [OH] ratio of 5.

[0079] After mixing A and B evenly, adhesive 7 is prepared, which is used as the adhesive layer of the battery outer packaging material.

[0080] II. Production of battery packaging materials:

[0081] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Then, an outer adhesive layer is coated on one side at a coating amount of 3 g / m2, and oven-dried at 80°C. A 25-micron biaxially stretched polyamide film (i.e., the substrate layer) is then bonded to the outer adhesive layer using a hot roller, and aged at 60°C for 7 days. After aging, a 40-micron acid-modified polyolefin (sealing layer) is bonded to the inner layer of the aluminum foil and treated at 180°C, then cooled to room temperature to obtain battery packaging material 7.

[0082] Comparative Example 2

[0083] I. Preparation of the adhesive layer:

[0084] The adhesive layer is composed of a two-component solvent-based polyurethane adhesive, which includes a main agent (referred to as component A) and a curing agent (referred to as component B). Component A contains polyester polyol (A1) and comb copolymer (A2), and the molar ratio of polyester polyol (A1) and comb copolymer (A2) is determined to be 0.5.

[0085] The A1 component polyester polyol is formed by high-temperature condensation polymerization of 99.67g isophthalic acid, 58.45g adipic acid, and 104.15g neopentyl glycol, wherein the aromatic diacid accounts for 60% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 6000.

[0086] Component A2 is prepared by free radical copolymerization of 86.08g of methyl acrylate and 250g of allyl polyethylene glycol ether with a number average molecular weight of 1000, wherein methyl acrylate accounts for 80% of the total molar content and the copolymer has a molecular weight of 10000.

[0087] Component B is a trimer formed by the reaction of isocyanate TDI and chain extender TMP, with a final [NCO] / [OH] ratio of 5.

[0088] After mixing A1, A2, and B evenly, adhesive 8 is prepared and used as the adhesive layer for the outer packaging material of the battery.

[0089] II. Production of battery packaging materials:

[0090] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Then, an outer adhesive layer is coated on one side at a coating amount of 3 g / m2, and oven-dried at 80°C. A 25-micron biaxially stretched polyamide film (i.e., the substrate layer) is then bonded to the outer adhesive layer using a hot roller, and aged at 60°C for 7 days. After aging, a 40-micron acid-modified polyolefin (sealing layer) is bonded to the inner layer of the aluminum foil and treated at 180°C, then cooled to room temperature to obtain battery packaging material 8.

[0091] Comparative Example 3

[0092] I. Preparation of the adhesive layer:

[0093] The adhesive layer is composed of a two-component solvent-based polyurethane adhesive, which includes a main agent (referred to as component A) and a curing agent (referred to as component B). Component A contains polyester polyol (A1) and comb copolymer (A2), and the molar ratio of polyester polyol (A1) and comb copolymer (A2) is determined to be 8.

[0094] The A1 component polyester polyol is formed by high-temperature condensation polymerization of 99.67g isophthalic acid, 58.45g adipic acid, and 104.15g neopentyl glycol, wherein the aromatic diacid accounts for 60% of the diacid molar ratio, and the number average molecular weight of the polyester polyol is 6000.

[0095] Component A2 is prepared by free radical copolymerization of 86.08g of methyl acrylate and 250g of allyl polyethylene glycol ether with a number average molecular weight of 1000, wherein methyl acrylate accounts for 80% of the total molar content and the copolymer has a molecular weight of 10000.

[0096] Component B is a trimer formed by the reaction of isocyanate TDI and chain extender TMP, with a final [NCO] / [OH] ratio of 5.

[0097] After mixing A1, A2, and B evenly, adhesive 9 is prepared and used as the adhesive layer for the outer packaging material of the battery.

[0098] II. Production of battery packaging materials:

[0099] From the outside in, the layers are stacked sequentially as follows: substrate layer 1, outer adhesive layer 2, metal layer 3, and sealing layer 4. First, a 40-micron aluminum foil (i.e., the metal layer) is surface-treated by coating with a phosphoric acid solution of chromic acid and acrylic resin, and then oven-dried at 190°C for 1 minute. Then, an outer adhesive layer is coated on one side at a coating amount of 3 g / m2, and oven-dried at 80°C. A 25-micron biaxially stretched polyamide film (i.e., the substrate layer) is then bonded to the outer adhesive layer using a hot roller, and aged at 60°C for 7 days. After aging, a 40-micron acid-modified polyolefin (sealing layer) is bonded to the inner layer of the aluminum foil and treated at 180°C, then cooled to room temperature to obtain the battery packaging material 9.

[0100] Table 1 below shows the composition and proportion of the adhesives in Examples 1-6 and Comparative Examples 1-3:

[0101] Table 1

[0102]

[0103]

[0104] Performance and Testing

[0105] The peel strength, molding limit, and post-molding performance of the battery packaging materials prepared in each embodiment and comparative example were tested.

[0106] The test results are shown in Table 2 below:

[0107] Table 2

[0108]

[0109] According to the test results in Table 2 above, the peel strength, molding limit, and long-term performance after molding of each embodiment are significantly better than those of the comparative examples. This indicates that the adhesive strength and drawing performance of the products in each embodiment are improved compared to the comparative examples. This is because the addition of the comb copolymer can improve the water resistance and crosslinking density of the adhesive, and increase the strength of the polymer interpenetrating network. Specifically, compared with Example 1, the results of Comparative Example 1 show the necessity of adding the comb copolymer, which can significantly improve moldability and water resistance; the results of Comparative Example 2 show that adding too much comb copolymer will lead to a decrease in molding limit and peel strength; the results of Comparative Example 3 show that adding too little comb copolymer cannot effectively improve the overall performance of the sample. In summary, the addition of an appropriate proportion of comb copolymer can significantly improve the peel performance and molding performance of battery packaging materials, giving the product a higher molding limit and long-term stability, and bringing the product a wider range of applications and scenarios.

[0110] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. Battery outer packaging material, characterized in that, From the outside in, it includes a substrate layer, an adhesive layer, a metal layer, and a sealing layer. The substrate layer is a biaxially stretched polymer film with a thickness of 10μm to 50μm; The metal layer is a metal with a thickness of 10μm to 100μm; The sealing layer is made of thermoplastic resin; The adhesive layer comprises, by molar fraction, 5–25 mol% polyester polyol, 1–5 mol% comb copolymer, and 20–100 mol% modified polyisocyanate curing agent; The dicarboxylic acid segment of the polyester polyol includes an aromatic dicarboxylic acid segment, and the molar fraction of the aromatic dicarboxylic acid segment in the dicarboxylic acid segment is 60-90 mol%. The number average molecular weight of the polyester polyol is 6,000 to 30,000; the comb copolymer is a copolymer with a molecular weight of 1,000 to 6,000, obtained by copolymerizing unsaturated acrylate monomers and unsaturated polyether monomers. The unsaturated acrylate monomers include one or more of methyl acrylate, ethyl acrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, hydroxybutyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, and butyl methacrylate; the unsaturated polyether monomers include one or more of allyl polyethylene glycol ether, isobutylene polyethylene glycol ether, isopentenyl polyethylene glycol ether, and ethylene glycol monovinyl polyethylene glycol ether.

2. The battery outer packaging material according to claim 1, characterized in that, The substrate layer is one or more of polyethylene terephthalate film, polybutylene terephthalate film, and polyamide film.

3. The battery outer packaging material according to claim 1, characterized in that, The modified polyisocyanate curing agent is a polyisocyanate treated with a chain extender, wherein the polyisocyanate is one or more of hexamethylene diisocyanate, isophorone diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; and the chain extender is one or more of trimethylolpropane, methylpentane glycol, dimethylbutane glycol, ethylene glycol, and glycerol.

4. The battery outer packaging material according to claim 1, characterized in that, According to the molar concentration meter, the isocyanate group [NCO] of the modified polyisocyanate curing agent and the hydroxyl group [OH] of the polyester polyol and polycarboxylic acid comb copolymer have an equivalent ratio of [NCO] / [OH] of 5 to 25.

5. The battery outer packaging material according to claim 1, characterized in that, The thermoplastic resin is one or more of polyolefin, cyclic polyolefin, acid-modified polyolefin, and acid-modified cyclic polyolefin.

6. A battery, characterized in that, The battery outer packaging material according to any one of claims 1 to 5 contains a battery element having at least a positive electrode, a negative electrode, and an electrolyte.

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