High-adhesion polyurethane adhesive for lithium ion battery and preparation method of high-adhesion polyurethane adhesive

Abstract

The invention discloses a high-adhesion polyurethane adhesive for a lithium ion battery and a preparation method of the high-adhesion polyurethane adhesive. The polyurethane adhesive is obtained by reacting (A) polyisocyanate, (B1) polyolefin polyol and optional polycarbonate polyol, (C) dihydric alcohol or diamine containing cyano groups, (D) a compound with groups having affinity with metals and more than one reactive hydrogen, and (E) a cross-linking agent, alternatively, (A) a polyisocyanate, (B2) an acrylonitrile-modified polyolefin polyol, (D) a compound having a group having affinity for metals and one or more reactive hydrogen atoms, and (E) a cross-linking agent are used to react with each other. The cyano group can be introduced by using acrylonitrile modified polyolefin polyol or cyano group-containing dihydric alcohol or diamine, so that the adhesive strength of the polyurethane adhesive can be improved, and the adhesion of an active substance and the current collector is facilitated.

Description

Technical Field

[0001] The present invention relates to the fields of batteries and adhesives, and particularly to a polyurethane adhesive for lithium-ion batteries. Background Art

[0002] Lithium-ion batteries have higher battery efficiency and energy density compared to other secondary batteries, and thus are the most widely used secondary batteries. Their working principle is to achieve repeated charging through the reversible insertion and extraction of lithium ions into and out of the positive and negative electrode materials. According to predictions, by 2030, the compound annual growth rate of lithium-ion battery shipments will exceed 25%, and the usage amount of the negative electrode adhesive will also increase significantly, presenting a very broad market prospect.

[0003] During the production process of lithium-ion batteries, the positive and negative electrode active materials and conductive materials need to be adhered to the metal foil serving as the current collector through an adhesive. Therefore, the performance of the battery is not only related to the main materials such as the active materials, conductive materials, electrolyte, and current collector used, but also affected by the adhesive used. Specifically, the electrode active materials are adhered to the current collector through the adhesive force provided by the adhesive. Therefore, the stronger the adhesive force of the adhesive, the smoother the movement of lithium ions and electrons between the active materials and between the active materials and the current collector, the lower the internal resistance of the battery, and the higher the charge-discharge efficiency. At the same time, in the battery anode, regardless of whether the active material used is graphite or silicon-carbon, silicon-oxygen, these active materials will undergo significant system expansion and contraction during charge and discharge. Among them, the system expansion of graphite is relatively small, about 30% or so, while the system expansion of the silicon-based negative electrode active material can even be higher than 300%. Therefore, the adhesive needs to have sufficient adhesive force to ensure the conduction of electrons and lithium ions between the active materials and between the active materials and the current collector during the process of volume expansion and contraction of the active materials.

[0004] CN113711383A discloses a polyurethane binder composition for electrodes with high durability, in which the polyurethane is obtained by reacting a polyisocyanate, a polyol, a compound having a hydrophilic group and more than 1 active hydrogen, and a chain extender. The adhesive of this patent has flexibility, and thus can maintain the characteristic that the electrode composite layer is not easily peeled off during electrode processing, but the adhesive force performance is poor. CN107200824A discloses a polyurethane aqueous dispersion with good expansion performance and high char residue amount during combustion used as a fireproof coating. By introducing a cyano group into the polyurethane and utilizing its "secondary film-forming" characteristic, that is, forming a nitrogen-containing condensed ring compound during the combustion process, and then de-nitrifying at high temperature to form a condensed ring carbon compound structure similar to graphite, the char residue amount during the pyrolysis of the latex film is increased, effectively improving the flame retardant performance of the coating film. Summary of the Invention

[0005] Aiming at the problem of poor adhesive force of existing adhesives for lithium-ion batteries, the purpose of the present invention is to provide a polyurethane adhesive for lithium-ion batteries with high adhesive force and its preparation method. By introducing cyano groups into the polyurethane or polyurethane-urea system, the adhesive force of the adhesive is improved, and it can be applied to the positive and negative electrodes of lithium-ion batteries.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The present invention provides a polyurethane adhesive for lithium-ion batteries with high adhesive force, which comprises the following components:

[0008] (1) When introducing cyano groups into the hard segment of polyurethane,

[0009] (A) The dosage of polyisocyanate is 10.0 - 35.0 wt%, preferably 18.0 - 26.0 wt%;

[0010] (B1) The dosage of polyolefin polyol is 50.0 - 75.0 wt%, and the dosage of polycarbonate polyol is 0.0 - 10.0 wt%;

[0011] (C) The dosage of diol or diamine containing cyano is 0.1 - 10.0 wt%, preferably 0.5 - 5.0 wt%;

[0012] (D) The dosage of a compound having an affinity group for metal and more than 1 active hydrogen is 1.0 - 15.0 wt%, preferably 1.5 - 10.0 wt%;

[0013] (E) The dosage of crosslinking agent is 0.5 - 1.5 wt%, preferably 0.6 - 1.0 wt%;

[0014] Or; (2) When introducing cyano groups into the soft segment of polyurethane,

[0015] (A) The dosage of polyisocyanate is 15.0 - 25.0 wt%;

[0016] (B2) The dosage of acrylonitrile-modified polyolefin polyol is 65.0 - 80.0 wt%;

[0017] (D) The dosage of a compound having an affinity group for metal and more than 1 active hydrogen is 1.0 - 15.0 wt%, preferably 1.5 - 10.0 wt%;

[0018] (E) The dosage of crosslinking agent is 0.5 - 1.5 wt%, preferably 0.6 - 1.0 wt%.

[0019] The (A) polyisocyanate in the present invention is one or more of aliphatic isocyanates, alicyclic isocyanates, and aromatic isocyanates. Suitable examples include, but are not limited to, toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, dodecamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate, benzenedimethylene diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, etc., and also includes any one or more of the polymers or modified products of these polyisocyanates.

[0020] The polyolefin polyol in the (B1) of the present invention is one or more of polyisoprene polyol, hydrogenated polyisoprene polyol, hydroxyl-terminated polybutadiene-acrylonitrile, hydroxyl-terminated polyisoprene-acrylonitrile, polybutadiene polyol, hydrogenated polybutadiene polyol, and their modified products. The number-average molecular weight of the polyolefin polyol is preferably 500 - 8000 g / mol, more preferably 1000 - 5000 g / mol.

[0021] The polycarbonate polyol in the (B1) of the present invention includes, but is not limited to, one or more of polycarbonate diols. The number-average molecular weight of the polycarbonate polyol is preferably 350 - 4000 g / mol, preferably 500 - 2000 g / mol.

[0022] The acrylonitrile-modified polyolefin polyol in the (B2) of the present invention is hydroxyl-terminated polybutadiene-acrylonitrile or hydroxyl-terminated polyisoprene-acrylonitrile, in which the mass fraction of acrylonitrile is 1.0 - 30.0 wt%, preferably 3.0 - 22.0 wt%.

[0023] The (C) diol or diamine containing a cyano group in the present invention has the structural formula: Wherein, X represents an alkyl group, a cycloalkyl group, or an aromatic group, Y represents a hydroxyl group or an amino group, and n is an integer selected from 1 - 3.

[0024] As a preferred embodiment, the (C) includes, but is not limited to, one or more of diaminomaleonitrile, 2,4-dihydroxy-3,3-dimethylbutyronitrile, (S)-3,4-dihydroxybutyronitrile, 3,4-diaminobenzonitrile, 2,3-dicyanohydroquinone, 3,6-dihydroxyphthalonitrile, 2,3-dihydroxybenzonitrile, 2,4-dihydroxybenzonitrile, 2,3-diamino-1,4-phthalodinitrile, 1,4-diamino-2,5-dicyanobenzene, 2,5-diaminobenzonitrile. Among them, the diamine containing a cyano group is preferred because it can introduce more hydrogen bond donors, increase the interaction between hard segments, and further improve the peel strength.

[0025] The (D) in the present invention is a compound having a group affinity for metal and one or more active hydrogens. The group having an affinity for metal includes, but is not limited to, one or more of carboxyl group, hydroxyl group, sulfonic acid group, pyridyl group, ester group, amide group, ethoxy group, cyano group, carboxylic anhydride, epoxy group, mercapto group, quinolinyl group, oxazolinyl group. Suitable examples include, but are not limited to, carboxylic acid compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, 2,6-dihydroxybenzoic acid, dihydroxymaleic acid and their salts; amino acid compounds such as glycine, alanine, aminobutyric acid, aminovaleric acid, aminohexanoic acid, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine; sulfonic acid compounds such as 1,2-dihydroxy-3-propanesulfonic acid, 2-(2-aminoethyl)aminoethanesulfonic acid, 2-(2-aminoethyl)aminopropanesulfonic acid and 1,4-butanediol-2-sulfonic acid and their salts.

[0026] The (E) crosslinking agent in the present invention is not particularly limited and can be a triamine or a tetraamine, etc. For example, triamines such as diethylenetriamine, dipropylenetriamine, and tetraamines such as triethylenetetramine.

[0027] A method for preparing the polyurethane adhesive of the present invention includes the following steps:

[0028] (1) When introducing a cyano group into the polyurethane hard segment,

[0029] (1-1): React component A, component B1, component C and component D until the NCO reaches the theoretical value to generate a prepolymer;

[0030] (1-2-1): After cooling the prepolymer, neutralize it, add water and shear-disperse to obtain an emulsion, add component E, and remove the solvent to obtain an aqueous polyurethane emulsion; or,

[0031] (1-2-2): Neutralize the prepolymer after cooling, and add Component E to obtain the polyurethane solution;

[0032] (2) When introducing a cyano group into the soft segment of the polyurethane,

[0033] (2-1): React Component A, Component B2, and Component D until the NCO reaches the theoretical value to generate a prepolymer;

[0034] (2-2-1): Neutralize the prepolymer after cooling, add water and shear to disperse to obtain an emulsion, add Component E, and remove the solvent to obtain an aqueous polyurethane emulsion; or,

[0035] (2-2-2): Neutralize the prepolymer after cooling, and add Component E to obtain the polyurethane solution.

[0036] The preparation method described in the present invention can occur under solvent-free conditions or in organic solvents. The selection of solvents includes but is not limited to: any one or more of dioxane, methyl ethyl ketone, acetone, dimethylformamide, diethylformamide, dimethylacetamide, tetrahydrofuran, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone, N-butyl-2-pyrrolidone, benzene, toluene, xylene, mesitylene, chlorobenzene, dichlorobenzene, n-pentane, n-hexane, n-heptane, cyclohexane, propylene glycol monomethyl ether acetate; preferably, the solvents used are any one or more of methyl ethyl ketone, acetone, dimethylformamide, N-methyl-2-pyrrolidone, N-butyl-2-pyrrolidone, xylene, n-hexane, cyclohexane, chlorobenzene; more preferably, any one or more of methyl ethyl ketone, N-butyl-2-pyrrolidone, xylene, cyclohexane, chlorobenzene; particularly preferably, a mixed solvent of any one or more of methyl ethyl ketone, N-butyl-2-pyrrolidone, xylene.

[0037] The content of Component (B1) polyolefin polyol is preferably 50% by mass or more and 80% by mass or less relative to 100% by mass of the polyurethane, or the content of Component (B2) acrylonitrile-modified polyolefin polyol is preferably 65% by mass or more and 80% by mass or less relative to 100% by mass of the polyurethane. When the content is within this range, the electrochemical stability and electrolyte resistance of the polyurethane adhesive are particularly excellent.

[0038] The technical solution of the present invention has the following beneficial effects: Introducing a cyano group into the polyurethane chain structure, which has complexing properties and strong complexing ability with metals, can improve the adhesion between the main material and the current collector when used as a battery adhesive. Detailed implementation mode

[0039] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are shown in the examples, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0040] <Raw material source information>

[0041] Polyolefin polyol I: polybutadiene glycol, Mn=2000 g / mol, (LBH-P2000, CRAY VALLEY);

[0042] Polyolefin polyol II: hydrogenated polybutadiene diol, Mn=3000 g / mol, (HLBH-P3000, CRAYVALLEY);

[0043] Polyolefin polyol-acrylonitrile: acrylonitrile-modified polybutadiene diol, Mn=3000 g / mol, (HTBN-Ⅱ, Qilong Chemical);

[0044] Polycarbonate polyol: polycarbonate diol, Mn=1000 g / mol, (Eternacoll UH-100, UBE, Japan);

[0045] Polyisocyanate I: Hexamethylene diisocyanate ( HDI, Wanhua Chemical);

[0046] Polyisocyanate II: 1,4-cyclohexylmethane diisocyanate ( HMDI, Wanhua Chemical);

[0047] N-(2-aminoethyl)-2-aminoethanesulfonate ( A95, EVONIK, USA);

[0048] Dimethylolpropionic acid (DMPA, Pandex (Shanghai) International Trading Co., Ltd.);

[0049] Diethylenetriamine (DETA, MacLean)

[0050] 3,4-Diaminobenzonitrile (DABN, Inokane)

[0051] 3,6-Dihydroxyphthalonitrile (DCDQ, Aladdin)

[0052] Diaminomaleonitrile (DAMN, Inokane)

[0053] Dimethylbis[(neodecanoyl)oxy]dimethyltin(Sn Cat.BiDePharma)

[0054] N-Butylpyrrolidone (NBP, Komiou)

[0055] Butanone (Kermione)

[0056] Example 1 (Emulsion-type Anode Binder)

[0057] Add 170 g of dehydrated LBH-P2000, 60 g of HMDI, 5 g of DAMN, 10 g of DMPA, 250 g of methyl ethyl ketone, and 0.3 g of Sn Cat. into a 1 L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring, and heat to 90 °C for reaction for 4 h. Measure that the residual NCO in the prepolymer is 0.5%. After cooling the prepolymer to 60 °C, add 250 g of methyl ethyl ketone and continue to cool to 40 °C. Add 30 g of aqueous solution of 3.7 g of NaOH and stir for 10 min. Disperse in 750 g of aqueous solution with high-speed stirring for 10 min, then add 20 g of aqueous solution of 1.85 g of DETA, and continue stirring for 30 min. After distilling the crude emulsion to separate methyl ethyl ketone, adjust the solid content of the emulsion to 30 wt%.

[0058] Example 2 (Emulsion-type Anode Binder)

[0059] Add 120 g of dehydrated HLBH-P3000, 16 g of dehydrated UH-100, 50 g of HMDI, 6 g of DCDQ, 10 g of DMPA, 200 g of methyl ethyl ketone, and 0.3 g of Sn Cat. into a 1 L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring, and heat to 90 °C for reaction for 4 h. Measure that the residual NCO in the prepolymer is 0.5%. After cooling the prepolymer to 60 °C, add 250 g of methyl ethyl ketone and continue to cool to 40 °C. Add 30 g of aqueous solution of 3.7 g of NaOH and stir for 10 min. Disperse in 750 g of aqueous solution with high-speed stirring for 10 min, then add 20 g of aqueous solution of 1.5 g of DETA, and continue stirring for 30 min. After distilling the crude emulsion to separate methyl ethyl ketone, adjust the solid content of the emulsion to 30 wt%.

[0060] Example 3 (Emulsion-type Anode Binder)

[0061] Add 190 g of dehydrated HTBN-II, 54 g of HMDI, 7 g of HDI, 20 g of DMPA, 250 g of methyl ethyl ketone, and 0.3 g of Sn Cat. into a 1 L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring, and heat to 90 °C for reaction for 4 h. Measure that the residual NCO in the prepolymer is 0.5%. After cooling the prepolymer to 60 °C, add 250 g of methyl ethyl ketone and continue to cool to 40 °C. Add 30 g of aqueous solution of 3.7 g of NaOH and stir for 10 min. Disperse in 800 g of aqueous solution with high-speed stirring for 10 min, then add 20 g of aqueous solution of 2 g of DETA, and continue stirring for 30 min. After distilling the crude emulsion to separate methyl ethyl ketone, adjust the solid content of the emulsion to 30 wt%.

[0062] Example 4 (Emulsion-type Anode Binder)

[0063] Add 170 g of dehydrated LBH-P2000, 60 g of HMDI, 5 g of DABN, 10 g of DMPA, 250 g of methyl ethyl ketone, and 0.3 g of Sn Cat. into a 1-L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring, and heat to 90 °C for reaction for 4 h. Measure that the residual NCO in the prepolymer is 0.5%. After cooling the prepolymer to 60 °C, add 250 g of methyl ethyl ketone and continue to cool to 40 °C. Add 30 g of aqueous solution of 3.7 g of NaOH and stir for 10 min. Disperse in 750 g of aqueous solution under high-speed stirring for 10 min, then add 20 g of aqueous solution of 1.85 g of DETA and continue stirring for 30 min. After distilling the crude emulsion to separate methyl ethyl ketone, adjust the solid content of the emulsion to 30 wt%.

[0064] Example 5 (Solution-type Cathode Binder)

[0065] Add 170 g of dehydrated LBH-P2000, 61 g of HMDI, 2 g of DAMN, 13 g of DMPA, 990 g of NBP, and 0.3 g of Sn Cat. into a 2-L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring, and heat to 90 °C for reaction for 4 h. Add 1.8 g of DETA and continue stirring for 30 min to obtain a solution-type binder with a solid content of 20%.

[0066] Example 6 (Solution-type Cathode Binder)

[0067] Add 120 g of dehydrated HLBH-P3000, 16 g of dehydrated UH-100, 50 g of HMDI, 6 g of DCDQ, 10 g of DMPA, 815 g of NBP, and 0.3 g of Sn Cat. into a 2-L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring, and heat to 90 °C for reaction for 4 h. Add 1.5 g of DETA and continue stirring for 30 min to obtain a solution-type binder with a solid content of 20%.

[0068] Example 7 (Solution-type Cathode Binder)

[0069] Add 191 g of dehydrated HTBN-II, 47 g of HMDI, 12 g of DMPA, 1000 g of NBP, and 0.3 g of Sn Cat. into a 2-L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring, and heat to 90 °C for reaction for 4 h. Add 2 g of DETA and continue stirring for 30 min to obtain a solution-type binder with a solid content of 20%.

[0070] Example 8 (Solution-Type Positive Electrode Binder)

[0071] Add 170 g of dehydrated LBH-P2000, 64 g of HMDI, 12 g of DABN, 5 g of DMPA, 990 g of NBP, and 0.3 g of Sn Cat. into a 2 L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring and heat to 90 °C for reaction for 4 h. Add 1.74 g of DETA and continue stirring for 30 min to obtain a solution-type binder with a solid content of 20%.

[0072] Comparative Example 1 (Emulsion-Type Negative Electrode Binder)

[0073] Add 175 g of dehydrated LBH-P2000, 59 g of HMDI, 14 g of DMPA, 250 g of methyl ethyl ketone, and 0.3 g of Sn Cat. into a 1 L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring and heat to 90 °C for reaction for 4 h. Measure that the residual NCO in the prepolymer is 0.5%. After cooling the prepolymer to 60 °C, add 250 g of methyl ethyl ketone and continue to cool to 40 °C. Add 3.7 g of NaOH in 30 g of aqueous solution and stir for 10 min. Disperse in 750 g of aqueous solution with high-speed stirring for 10 min, then add 1.83 g of DETA in 20 g of aqueous solution and continue stirring for 30 min. After distilling the crude emulsion to separate out methyl ethyl ketone, adjust the solid content of the emulsion to 30 wt%.

[0074] Comparative Example 2 (Emulsion-Type Negative Electrode Binder)

[0075] Add 170 g of dehydrated HLBH-P3000, 18 g of dehydrated UH-100, 48 g of HMDI, 10 g of DMPA, 250 g of methyl ethyl ketone, and 0.3 g of Sn Cat. into a 1 L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring and heat to 90 °C for reaction for 4 h. Measure that the residual NCO in the prepolymer is 0.5%. After cooling the prepolymer to 60 °C, add 250 g of methyl ethyl ketone and continue to cool to 40 °C. Add 3.7 g of NaOH in 30 g of aqueous solution and stir for 10 min. Disperse in 750 g of aqueous solution with high-speed stirring for 10 min, then add 1.8 g of DETA in 20 g of aqueous solution and continue stirring for 30 min. After distilling the crude emulsion to separate out methyl ethyl ketone, adjust the solid content of the emulsion to 30 wt%.

[0076] Comparative Example 3 (Solution-Type Positive Electrode Binder)

[0077] Add 120 g of dehydrated HLBH-P3000, 16 g of dehydrated UH-100, 50 g of HMDI, 15 g of DMPA, 815 g of NBP, and 0.3 g of Sn Cat. into a 2 L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring and heat to 90 °C for reaction for 4 h. Add 1.5 g of DETA and continue stirring for 30 min to obtain a solution-type binder with a solid content of 20%.

[0078] Comparative Example 4 (Solution-Type Positive Electrode Binder)

[0079] Add 185 g of dehydrated LBH-P2000, 53 g of HMDI, 12 g of DMPA, 1000 g of NBP, and 0.3 g of Sn Cat. into a 2 L four-necked round-bottom flask. Introduce nitrogen into the four-necked round-bottom flask, start stirring and heat to 90 °C for reaction for 4 h. Add 2 g of DETA and continue stirring for 30 min to obtain a solution-type binder with a solid content of 20%.

[0080] Preparation of Electrode Sheets

[0081] (1) Preparation of negative electrode sheet: Add 1 part of sodium carboxymethyl cellulose (CMC) to 99 parts of deionized water and stir at high speed for half an hour. Then add 1 part of conductive carbon black (Super P), 96 parts of graphite, and 2 parts of the above-prepared emulsion-type negative electrode binder, and stir at high speed for about ten minutes to obtain a negative electrode slurry. Coat the negative electrode slurry evenly on the copper foil with a thickness of 200 μm, place it in an oven at 90 °C for drying for 5 minutes, take it out and cool it to room temperature, and roll it to obtain a negative electrode sheet with a thickness of 120 μm.

[0082] (2) Preparation of positive electrode sheet: Add 95 parts of active material (five-series ternary material), 2 parts of conductive agent (acetylene black), and 3 parts of the above-prepared solution-type positive electrode binder to 100 parts of NMP, and stir at high speed for about half an hour to obtain a positive electrode slurry. Coat the positive electrode slurry evenly on the aluminum foil with a thickness of 200 μm, place it in an oven at 120 °C for drying for half an hour, take it out and cool it to room temperature, and roll it to obtain a positive electrode sheet with a thickness of 120 μm.

[0083] Evaluation of electrolyte swelling: Dry the above-prepared emulsion-type negative electrode binder or solution-type positive electrode binder into a film in an oven at 90 °C, and take a film piece with a mass of M1. Immerse the film piece in the electrolyte and place it in an oven at 60 °C for heat preservation for 48 hours. Wipe the electrolyte on the surface of the film piece dry with filter paper and weigh it as M2. Electrolyte swelling degree = (M2 - M1) / M1 × 100%.

[0084] Peeling Strength Evaluation: The test method for peeling strength refers to the American Society for Testing and Materials (ASTM) standard ASTM D3330, and the equipment used is a computerized tensile testing machine (KJ-1065).

[0085] Diaphragm Mechanical Property Evaluation: Take 30 g of adhesive and place it in a mold with dimensions of 20 * 20 cm, and dry it in an oven at 90 °C for 24 h to obtain an adhesive diaphragm. Take some diaphragms and conduct tensile tests in accordance with GB / T 1040.1-2018.

[0086] The performance test results are shown in Table 1.

[0087] Table 1 Performance Test Results

[0088]

[0089]

Claims

1. A polyurethane adhesive for high adhesion lithium-ion batteries, which comprises the following components: (1) When introducing a cyano group into the polyurethane hard segment, (A) The dosage of polyisocyanate is 10.0 - 35.0 wt%, preferably 18.0 - 26.0 wt%; (B1) The dosage of polyolefin polyol is 50.0 - 75.0 wt%, and the dosage of polycarbonate polyol is 0.0 - 10.0 wt%; (C) The dosage of diol or diamine containing a cyano group is 0.1 - 10.0 wt%, preferably 0.5 - 5.0 wt%; (D) The dosage of a compound having a group affinity for metal and more than 1 active hydrogen is 1.0 - 15.0 wt%, preferably 1.5 - 10.0 wt%; (E) The dosage of crosslinking agent is 0.5 - 1.5 wt%, preferably 0.6 - 1.0 wt%; Or; (2) When introducing a cyano group into the polyurethane soft segment, (A) The dosage of polyisocyanate is 15.0 - 25.0 wt%; (B2) The dosage of acrylonitrile-modified polyolefin polyol is 65.0 - 80.0 wt%; (D) The dosage of a compound having a group affinity for metal and more than 1 active hydrogen is 1.0 - 15.0 wt%, preferably 1.5 - 10.0 wt%; (E) The dosage of crosslinking agent is 0.5 - 1.5 wt%, preferably 0.6 - 1.0 wt%.

2. The polyurethane adhesive according to claim 1, wherein, The (A) polyisocyanate is one or more of aliphatic chain isocyanates, alicyclic isocyanates and aromatic isocyanates; preferably toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,4-cyclohexane diisocyanate, dodecamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 1,5-naphthalene diisocyanate, 1,4-phenylene diisocyanate, benzylidene diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2-methylpentane-1,5-diisocyanate, 3-methylpentane-1,5-diisocyanate, or one or more of the polymers or modified products of these polyisocyanates.

3. The polyurethane adhesive according to claim 1 or 2, characterized in that, The polyolefin polyol in (B1) is one or more of polyisoprene polyol, hydrogenated polyisoprene polyol, hydroxyl-terminated polybutadiene-acrylonitrile, hydroxyl-terminated polyisoprene-acrylonitrile, polybutadiene polyol, hydrogenated polybutadiene polyol and their modified products; the number average molecular weight of the polyolefin polyol is 500 - 8000 g / mol, preferably 1000 - 5000 g / mol.

4. The polyurethane adhesive according to any one of claims 1-3, characterized in that, The polycarbonate polyol in (B1) is selected from one or more of polycarbonate diols; the number average molecular weight of the polycarbonate polyol is 350 - 4000 g / mol, preferably 500 - 2000 g / mol.

5. The polyurethane adhesive according to any one of claims 1-4, characterized in that, The (B2) acrylonitrile-modified polyolefin polyol is hydroxyl polybutadiene-acrylonitrile or hydroxyl-terminated polyisoprene-acrylonitrile, wherein the mass fraction of acrylonitrile is 1.0-30.0 wt%, preferably 3.0-22.0 wt%.

6. The polyurethane adhesive according to any one of claims 1-5, characterized in that, The (C) is a cyanide group-containing diol or diamine, and its structural formula is: wherein, X represents an alkyl group, a cycloalkyl group or an aryl group, Y represents a hydroxyl group or an amino group, and n is an integer selected from 1 to 3.

7. The polyurethane adhesive according to any one of claims 1-6, characterized in that, The (C) is selected from one or more of diaminomaleonitrile, 2,4-dihydroxy-3,3-dimethylbutyronitrile, (S)-3,4-dihydroxybutyronitrile, 3,4-diaminobenzonitrile, 2,3-dicyanohydroquinone, 3,6-dihydroxyphthalonitrile, 2,3-dihydroxybenzonitrile, 2,4-dihydroxybenzonitrile, 2,3-diamino-1,4-phthalodinitrile, 1,4-diamino-2,5-D dicyanobenzene, 2,5-diaminobenzonitrile.

8. The polyurethane adhesive according to any one of claims 1-7, characterized in that, The (D) is selected from carboxylic acid-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 2,2-dimethylolvaleric acid, 2,6-dihydroxybenzoic acid, dihydroxymaleic acid and their salts; amino acids such as glycine, alanine, aminobutyric acid, aminovaleric acid, aminohexanoic acid, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, histidine; sulfonic acid-containing compounds such as 1,2-dihydroxy-3-propanesulfonic acid, 2-(2-aminoethyl)aminoethanesulfonic acid, 2-(2-aminoethyl)aminopropanesulfonic acid and 1,4-butanediol-2-sulfonic acid and their salts.

9. The polyurethane adhesive according to any one of claims 1-8, characterized in that, The (E) crosslinking agent is selected from diethylenetriamine, dipropylenetriamine, triethylenetetramine.

10. A method for preparing the polyurethane adhesive according to any one of claims 1-9, comprising the following steps: (1) When introducing a cyano group into the polyurethane hard segment, (1-1): React component A, component B1, component C and component D until the NCO reaches the theoretical value to generate a prepolymer; (1-2-1): Cool the prepolymer, neutralize it, shear-disperse it with water to obtain an emulsion, add component E, and remove the solvent to obtain an aqueous polyurethane emulsion; or, (1-2-2): Cool the prepolymer, neutralize it, add component E to obtain a polyurethane solution; (2) When introducing a cyano group into the polyurethane soft segment, (2-1): React component A, component B2 and component D until the NCO reaches the theoretical value to generate a prepolymer; (2-2-1): Cool the prepolymer, neutralize it, shear-disperse it with water to obtain an emulsion, add component E, and remove the solvent to obtain an aqueous polyurethane emulsion; or, (2-2-2): Cool the prepolymer, neutralize it, add component E to obtain a polyurethane solution.

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