Anionic waterborne polyurethane resin for battery negative electrode binder as well as preparation method and application of anionic waterborne polyurethane resin

Abstract

The invention relates to anionic waterborne polyurethane resin for a battery negative electrode binder as well as a preparation method and application of the anionic waterborne polyurethane resin, and mainly solves the problems of low binding strength, poor electrolyte resistance stability and low conductivity of a common battery negative electrode binder in the prior art. According to the technical scheme of the anionic waterborne polyurethane resin with the structural formula (I) for the battery negative electrode binder and the preparation method of the anionic waterborne polyurethane resin, the problems are well solved, and the anionic waterborne polyurethane resin can be applied to the battery negative electrode binder.

Description

TECHNICAL FIELD

[0001] The present application relates to an anionic water-based polyurethane resin for battery negative electrode binder, its preparation method and application. BACKGROUND

[0002] The most common materials of battery negative electrode binder on the market are mainly SBR and CMC, which are often used together. In addition, PAA is also commonly used.

[0003] SBR and CMC compound solution is the most commonly used binder for battery negative electrode at present, which has the advantages of low cost, good processability and strong adaptability to graphite negative electrode, but has the disadvantages of long gluing time, low bonding strength, and gradually highlighted limitations in the face of high-capacity, high-volume expansion of new negative electrode (such as silicon-based) and high-performance battery demand.

[0004] Using PAA as a battery negative electrode binder has the advantages of high cohesion and excellent electrolyte resistance, but the disadvantage is that the material is hard and lacks flexibility, which can easily lead to the peeling of the negative electrode material after expansion when used alone, and it is usually necessary to be used in combination with a flexible binder such as SBR. In addition, the carboxylic acid group may be reduced, causing interface side reactions and affecting battery performance.

[0005] Water-based polyurethane binder has excellent bonding performance and interface compatibility, good flexibility and anti-volume expansion ability, outstanding electrolyte resistance performance, is easy to process and environmentally friendly, and is a good choice as a battery negative electrode binder.

[0006] Chinese patent CN117987050A discloses a water-based binder, a preparation method, a battery pole piece and a sodium ion battery material. The binder includes, by mass fraction: polyethylene glycol 5-25 parts, diisocyanate 5-25 parts, acrylic ester 1-15 parts, acrylic acid 5-20 parts, acrylonitrile 5-15 parts, and acrylamide 5-15 parts. The polyurethane modified acrylic water-based binder is rich in polar functional groups and linear structure, which can provide strong adhesion, cohesion and flexibility, and can effectively replace the SBR+CMC system in amorphous carbon material application. However, there is no mention of electrolyte resistance stability and electrical conductivity, and the maximum peel strength is 0.0657 N / m; the polyurethane modified polyamide (i.e. PUA) molecular chain does not have positive and negative ions, and additional charged additives are needed to improve the conductivity, which is a complex process; and the polyethylene glycol modified acrylic acid does not improve the heat resistance of PUA, and the bonding performance will decrease significantly at high temperatures (> 80 degrees); in addition, the PUA urethane group is also prone to hydrolysis, which requires higher conditions during use and storage. SUMMARY

[0007] The present application solves one of the technical problems that the existing ordinary battery negative electrode binder has low bonding strength, poor electrolyte stability and low conductivity, and provides an anionic water-based polyurethane resin for a battery negative electrode binder, which has the advantages of high bonding strength, good electrolyte stability and high conductivity.

[0008] The second technical problem solved by the present application is to provide a preparation method of the water-based polyurethane resin corresponding to the first technical problem.

[0009] The third technical problem solved by the present application is to provide an application of the water-based polyurethane resin corresponding to the first technical problem.

[0010] To solve the first technical problem, the technical solution adopted by the present application is as follows: an anionic water-based polyurethane resin for a battery negative electrode binder has a chemical structural formula (I) as follows:

[0011]

[0012] In the formula, n is an integer in the range of 1-100;

[0013] R1 is a polyol with a molecular weight of 1000-3000, and its general structure is as follows:

[0014]

[0015] R2 is a diisocyanate, and its general structure is as follows:

[0016]

[0017] R3 is a small molecular alcohol chain extender with a molecular weight of less than 500, and its general structure is as follows:

[0018]

[0019] R4 is a binary small molecular amine selected from at least one of isophorone diamine, ethylenediamine and hydroxyethylenediamine, and its general structure is at least one of the following structures:

[0020]

[0021] R5 is a hydrophilic chain extender selected from at least one of sulfonate modified polyol, hydroxyl sulfonate, aminosulfonate aqueous solution and small molecular sulfonate diamine, and its general structure is at least one of the following structures:

[0022]

[0023] To solve the above technical problems, the application adopts the following technical solutions: a preparation method of an anionic water-based polyurethane resin for battery negative electrode binder, comprising the following steps in sequence by weight fraction:

[0024] (1) first dehydrate 150-300 parts of polyol at 100-120 DEG C for 20-40 min, then cool to 70-90 DEG C, add 10-100 parts of diisocyanate and 0.02-0.05 parts of catalyst mixture, react for 2-4 h;

[0025] (2) add 1-3 parts of crosslinking agent and 3-6 parts of small molecule alcohol chain extender, continue to react at 70-90 DEG C for 1-3 h;

[0026] (3) after cooling to 40-50 DEG C, add 300-850 parts of diluent to reduce viscosity, stir for 10-15 min, then add 10-20 parts of hydrophilic chain extender and 4-8 parts of dihydric small molecule amine, react at 40-50 DEG C for 10-20 min, then add 300-850 parts of water dispersion, after the solution is deacetoned, add a latent curing agent to obtain an anionic water-based polyurethane resin for battery negative electrode binder.

[0027] In the above technical solution, the diisocyanate is selected from one or more of tetramethylxylylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, 1,6-hexane diisocyanate, naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate and polymethylene polyphenyl isocyanate.

[0028] In the above technical solution, the polyol is selected from one or more of adipic acid-based polyester polyol, phthalic anhydride-based polyester polyol, polycaprolactone polyol, aromatic polyester polyol, polypropylene oxide polyol, polyethylene oxide polyol, polytetrahydrofuran polyol and polycarbonate polyol.

[0029] In the above technical solution, the catalyst is selected from one or more of organic bismuth, dibutyltin dilaurate and triazine trimerization catalyst.

[0030] In the above technical solution, the small molecule alcohol chain extender is selected from one or more of propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanediol, ethyl butyl propylene glycol, cyclohexane dimethanol and ethylene glycol.

[0031] In the above technical solution, the crosslinking agent is selected from one or more of trimethylolpropane, glycerol and low molecular weight polycaprolactone.

[0032] The diluent is selected from one or a combination of dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, butanone and acetone.

[0033] In the technical solution, the water is deionized water.

[0034] To solve the above-mentioned technical problems, the application adopts the technical solution as follows: application of an anionic water-based polyurethane resin for battery negative electrode binder in a battery negative electrode binder.

[0035] The application provides an anionic water-based polyurethane resin for a battery negative electrode binder and a preparation method and application thereof. Different types of polyols are selected as PUD soft segment structures, so that the binder is endowed with flexibility and certain polarity adjustability. Different isocyanates are used as hard segment structures, so that the binder is endowed with high cohesion, and the binder has high bonding strength. By adjusting the ratio of the soft segment and the hard segment, different application requirements of the battery negative electrode binder can be met. The sulfonate is used as a hydrophilic chain extender. The chemical inertness of the sulfonate endows the PUD with excellent electrolyte resistance and weather resistance. The ionic structure also improves the conductivity of the PUD film. The PUD used as the battery negative electrode binder can realize zero VOC, non-toxicity and flammability risk, and meets environmental protection regulations. The application optimizes the molecular chain structure design and the formula process during the synthesis of the water-based polyurethane, and prepares the water-based polyurethane resin with high bonding strength, good electrolyte resistance stability and high conductivity, so that the product meets the mechanical properties (peeling strength of 30.68-40.27 N) of the adhesion of the battery negative electrode material in the use process, provides a good conductive environment due to the unique ionic structure, and also has the environmental protection property of the water-based material, and good technical results are achieved. DETAILED DESCRIPTION

[0036] The following is only a preferred embodiment of the application, and is not a limitation on the protection scope of the application. Any technical solution falling within the idea of the application should fall within the protection scope of the application. Minor improvements and refinements of the application made by those skilled in the art without departing from the principles of the application should also fall within the protection scope of the application.

[0037] Table 1: Raw material list

[0038]

[0039]

[0040] Example 1

[0041] (1) 300g PTMG2000 is first dehydrated at 120℃ for 20min, and then cooled to 75℃, 48g HDI, 12g IPDI and 200ppm organic bismuth are added and reacted for 3h;

[0042] (2) Add 1 g of TMP and 5 g of BDO, continue to react at 75°C for 2 h;

[0043] (3) After cooling to 50°C, add 620 g of acetone to reduce viscosity, stir for 10 min, then add 18 g of A95 and 6 g of AEEA, react at 40°C for 20 min, then add 620 g of water to disperse, and after removing acetone, an anionic waterborne polyurethane resin for battery negative electrode binder is obtained.

[0044] Example 2

[0045] (1) First, 300 g of PTMG2000 is vacuum dehydrated at 120°C for 20 min, then cooled to 75°C, 89 g of HMDI and 100 ppm of organic bismuth are added and reacted for 3 h;

[0046] (2) Add 1 g of TMP and 7 g of CHDM, continue to react at 75°C for 2 h;

[0047] (3) After cooling to 50°C, add 580 g of acetone to reduce viscosity, stir for 10 min, then add 16 g of A95 and 6 g of AEEA, react at 40°C for 20 min, then add 650 g of water to disperse, and after removing acetone, an anionic waterborne polyurethane resin for battery negative electrode binder is obtained.

[0048] Example 3

[0049] (1) First, 150 g of PCL2000 is vacuum dehydrated at 120°C for 30 min, then cooled to 80°C, 31 g of HDI and 100 ppm of organic bismuth are added and reacted for 3 h;

[0050] (2) Add 1 g of TMP and 2.5 g of BDO, continue to react at 80°C for 2 h;

[0051] (3) After cooling to 50°C, add 220 g of acetone to reduce viscosity, stir for 10 min, then add 9 g of A95 and 1.8 g of EDA, react at 40°C for 20 min, then add 220 g of water to disperse, and after removing acetone, an anionic waterborne polyurethane resin for battery negative electrode binder is obtained.

[0052] Example 4

[0053] (1) First, 200 g of PCDL2000 is vacuum dehydrated at 100°C for 40 min, then cooled to 75°C, 42.7 g of HMDI, 10.7 g of MDI and 100 ppm of organic bismuth are added and reacted for 3 h;

[0054] (2) Add 0.7 g of TMP and 2.7 g of BDO, continue to react at 75°C for 2 h;

[0055] (3) After cooling to 50°C, 373 g of acetone was added to reduce the viscosity, and after stirring for 10 min, 12 g of A95 and 4 g of AEEA were added. The reaction was carried out at 40°C for 20 min, and then 373 g of water was added for dispersion. After removing the acetone, an anionic waterborne polyurethane resin for a battery negative electrode binder was obtained.

[0056] Example 5

[0057] (1) 150 g of PCDL2000 was first dehydrated at 120°C for 25 min, and then cooled to 75°C. 50.74 g of TDI and 50 ppm of organic bismuth were added and reacted for 3 h;

[0058] (2) 3 g of TMP and 6 g of BDO were added, and the reaction was continued at 75°C for 2 h;

[0059] (3) After cooling to 50°C, 300 g of acetone was added to reduce the viscosity, and after stirring for 10 min, 9 g of A95 and 7 g of AEEA were added. The reaction was carried out at 40°C for 20 min, and then 300 g of water was added for dispersion. After removing the acetone, an anionic waterborne polyurethane resin for a battery negative electrode binder was obtained.

[0060] Example 6

[0061] (1) 150 g of PCL2000 was first dehydrated at 120°C for 25 min, and then cooled to 90°C. 71.42 g of MDI, 9.4 g of IPDI, and 50 ppm of organic bismuth were added and reacted for 3 h;

[0062] (2) 3 g of TMP and 11.59 g of CHDM were added, and the reaction was continued at 75°C for 2 h;

[0063] (3) After cooling to 50°C, 300 g of acetone was added to reduce the viscosity, and after stirring for 10 min, 9 g of A95 and 4 g of EDA were added. The reaction was carried out at 40°C for 20 min, and then 300 g of water was added for dispersion. After removing the acetone, an anionic waterborne polyurethane resin for a battery negative electrode binder was obtained.

[0064] Comparative Example 1

[0065] CMC-Na powder was slowly added to deionized water (solid content 4%), and stirred at 700 rpm for 30 min until completely dissolved (no lumping), forming a transparent or translucent viscous solution, and standing to remove bubbles. The SBR latex (solid content 45%) was added to the CMC aqueous solution in proportion, and stirred at 300 rpm for 20 min to uniformly disperse the SBR latex particles in the CMC solution, forming a stable binder.

[0066] Comparative Example 2

[0067] The acrylic acid is added with sodium hydroxide to adjust the pH value to 6-8 to prepare an acrylic acid salt neutralization liquid, the acrylic acid salt neutralization liquid, acrylonitrile and acrylamide are stirred at 15 rad / s for 1 h to obtain a pre-emulsion, wherein the molar ratio of the hydroxyl acrylic acid monomer, acrylonitrile and acrylamide is 1.5:1.05:1.2. Under the protection of nitrogen atmosphere, the rotation speed is adjusted to 25 rad / s, the temperature is raised to 65°C, the initiator (ammonium persulfate aqueous solution, 0.05% of the monomer mass fraction) is added dropwise, the reaction temperature is controlled to be not higher than 80°C, and the reaction is carried out for 2 h. Water is added and stirred uniformly to obtain a PAA water-based adhesive.

[0068] Preparation of negative electrode slurry

[0069] The prepared adhesives of Examples 1-5 and Comparative Examples 1-2 are added to a negative electrode slurry system (the mass ratio of silicon-oxygen negative electrode, conductive carbon black, single-walled carbon nanotube and adhesive emulsion is 95:1:0.05:3.95), high-speed shearing stirring is carried out at 2000 r, the solid content is controlled to be 50%, the viscosity is controlled to be 5000 MPa*s (25°C), and finally a uniform negative electrode slurry is formed.

[0070] Table 2: Performance data of the battery negative electrode adhesives prepared in Examples 1-6 and Comparative Examples 1-2

[0071]

[0072] As shown in Table 2, the peel strength (30.68-40.27 N) and the cycle capacity retention rate (89.25-96.88%) of Examples 1-6 are better than those of Comparative Examples. The higher the peel strength, the higher the adhesive strength. The higher the cycle capacity retention rate, the better the electrolyte stability, and the higher the electrical conductivity. The molecular chain structure design and formula process optimization during the synthesis of the water-based polyurethane resin in the application prepare a water-based polyurethane resin with high adhesive strength, good electrolyte stability and high electrical conductivity. The product meets the mechanical properties of the battery negative electrode material adhesion during use, provides a good conductive environment due to the unique ion structure, and also has the environmental protection properties of water-based materials, achieving good technical results.

Claims

1. An anionic aqueous polyurethane resin for battery negative electrode binder, having a chemical formula of (I) as follows: ###0001### wherein n is an integer of 1-100; R1 is a polyol with a molecular weight of 1000-3000; R2 is a diisocyanate; R3 is a small molecular alcohol chain extender with a molecular weight of less than 500; R4 is a binary small molecular amine selected from at least one of isophorone diamine, ethylenediamine and hydroxyethylenediamine; and R5 is a hydrophilic chain extender selected from at least one of sulfonate modified polyol, hydroxysulfonate, aminosulfonate aqueous solution and small molecular sulfonate diamine.

2. A preparation method of the anionic aqueous polyurethane resin for battery negative electrode binder according to claim 1, comprising the following steps in sequence by weight fraction: (1) first dehydrating 150-300 parts of polyol at 100-120°C for 20-40 min, then cooling to 70-90°C, adding 10-100 parts of diisocyanate and 0.02-0.05 parts of catalyst for mixing, and reacting for 2-4 h; (2) adding 1-3 parts of crosslinking agent and 3-6 parts of small molecular alcohol chain extender, and continuing to react for 1-3 h at 70-90°C; (3) cooling to 40-50°C, adding 300-850 parts of diluent for viscosity reduction, stirring for 10-15 min, then adding 10-20 parts of hydrophilic chain extender and 4-8 parts of binary small molecular amine, and reacting for 10-20 min at 40-50°C, followed by adding 300-850 parts of water for dispersion, and adding latent curing agent to the solution after removal of acetone to obtain the anionic aqueous polyurethane resin for battery negative electrode binder. The diisocyanate is selected from one or more of tetramethylxylylene diisocyanate, toluene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, 1,6-hexanediisocyanate, naphthalene-1,5-diisocyanate, hexamethylene diisocyanate, methylcyclohexyl diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate and polymethylene polyphenyl isocyanate. The polyol is selected from one or more of adipic acid-based polyester polyol, phthalic anhydride-based polyester polyol, polycaprolactone polyol, aromatic polyester polyol, polypropylene oxide polyol, polyethylene oxide polyol, polytetrahydrofuran polyol and polycarbonate polyol. The catalyst is selected from one or more of organic bismuth, dibutyltin dilaurate and triazine-based trimerization catalyst. The small molecular alcohol chain extender is selected from one or more of propylene glycol, 1,4-butanediol, neopentyl glycol, 1,4-cyclohexanediol, ethyl butyl propylene glycol, cyclohexane dimethanol and ethylene glycol.

3. The method for preparing an anionic water-based polyurethane resin for a battery negative electrode binder according to claim 2, characterized by, The crosslinking agent is selected from one or more of trimethylolpropane, glycerol and low molecular weight polycaprolactone.

4. The method for preparing anionic aqueous polyurethane resin for battery negative electrode binder according to claim 2, characterized in that, The diluent is selected from a combination of one or more of dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, butanone and acetone.

5. The method for preparing anionic aqueous polyurethane resin for battery negative electrode binder according to claim 2, characterized in that, The water is deionized water.

6. The method for preparing anionic aqueous polyurethane resin for battery negative electrode binder according to claim 2, characterized in that, 10. Use of the anionic aqueous polyurethane resin for battery negative electrode binder according to claim 1 in a battery negative electrode binder.

7. The method for preparing anionic aqueous polyurethane resin for battery negative electrode binder according to claim 2, characterized in that, ​ 8. The method for preparing anionic aqueous polyurethane resin for battery negative electrode binder according to claim 2, characterized in that, ​ 9. The method for preparing anionic aqueous polyurethane resin for battery negative electrode binder according to claim 2, characterized in that, ​ ​

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