An aqueous polyurethane adhesive, a preparation method thereof and application thereof in new energy batteries

Abstract

The application discloses a kind of water-based polyurethane adhesive and its preparation method and application in new energy battery.The preparation method of water-based polyurethane adhesive of the application includes the following steps: the modified polyurethane prepolymer of polysaccharide or its derivative is mixed with at least one of the organic acid containing carbon-carbon double bond or its derivative, and free radical polymerization reaction occurs under the action of initiator, to obtain water-based polyurethane adhesive.The hydroxyl group in polysaccharide or its derivative is reacted with the isocyanate group in polyurethane prepolymer to form the modified polyurethane prepolymer of reticular structure, then free polymerization reaction occurs with the organic acid containing carbon-carbon double bond or its derivative to form three-dimensional interpenetrating network structure, and then effectively inhibit the volume expansion of silicon-based negative electrode material in the process of charging and discharging, so as to improve the cycle performance of battery.

Description

Technical Field

[0001] This invention relates to the field of polymer compound technology, and more specifically, to an aqueous polyurethane adhesive, its preparation method, and its application in new energy batteries. Background Technology

[0002] Compared to traditional gasoline-powered vehicles, electric vehicles (EVs), lacking engines and transmission systems, offer significant weight advantages when combined with high-strength steel, aluminum alloys, and plastic composite materials. Furthermore, the absence of combustion and the substantial energy consumption during transmission greatly enhances their energy efficiency. New energy batteries are the key energy storage component in EVs, primarily including lithium-ion and sodium-ion batteries. Currently, commercially available lithium-ion battery anode materials mainly consist of carbon materials, primarily graphite-based, and non-carbon materials, primarily silicon-based. Non-carbon materials, primarily silicon-based, have a higher theoretical specific capacity and are more suitable for high-energy-density lithium-ion batteries. However, in practical applications, it has been found that silicon-based anode materials experience severe volume expansion during lithium insertion / extraction, leading not only to electrochemical performance degradation but also to silicon particle cracking and pulverization, severely impacting the cycle performance of lithium-ion batteries.

[0003] To suppress the volume expansion of silicon-based anode materials during cycling, current methods mainly focus on the morphological structure design of the silicon-based anode materials (controlling particle size, surface modification, etc.) and the selection of highly elastic polymer binders. For example, existing technologies disclose a binder and a battery containing this binder, which uses acrylic polymers to form a three-dimensional network structure framework. The framework is connected by hydrogen bonds with polyurethane ternary polymers. The three-dimensional network structure and abundant hydrogen bonds provide good toughness and self-healing ability, but the effect of suppressing the volume expansion of silicon-based anode materials is limited, resulting in poor battery cycle performance. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects or deficiencies of existing polyurethane anode binders in effectively suppressing the volume expansion of silicon anode materials, and to provide a method for preparing a waterborne polyurethane binder.

[0005] Another object of the present invention is to provide a waterborne polyurethane adhesive.

[0006] Another object of the present invention is to provide an application of a waterborne polyurethane adhesive in new energy batteries.

[0007] Another object of the present invention is to provide a negative electrode slurry.

[0008] Another objective of this invention is to provide a negative electrode sheet.

[0009] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0010] This invention protects a method for preparing a waterborne polyurethane adhesive, specifically comprising the following steps:

[0011] A polyurethane prepolymer modified with polysaccharides or their derivatives is mixed with at least one of organic acids or their derivatives containing carbon-carbon double bonds, and undergoes a free radical polymerization reaction under the action of an initiator to obtain an aqueous polyurethane adhesive.

[0012] The polysaccharide- or derivative-modified polyurethane prepolymer is obtained by reacting polysaccharide or derivative with isocyanate-terminated polyurethane prepolymer via the reaction of hydroxyl groups and isocyanate groups.

[0013] This invention utilizes the reaction of hydroxyl groups in polysaccharides or their derivatives with isocyanate groups in polyurethane prepolymers to form a modified polyurethane prepolymer with a network structure. Under the action of an initiator, organic acids containing carbon-carbon double bonds or their derivatives undergo free polymerization with the modified polyurethane prepolymer to form an aqueous polyurethane binder with a rich cross-linked structure. The combination of isocyanate hard segments and polyether polyol soft segments in the polyurethane prepolymer forms a supporting framework that provides the necessary mechanical properties, toughness, and elasticity. Simultaneously, the reaction of hydroxyl groups in polysaccharides or their derivatives with isocyanate groups connects different polyurethane prepolymer segments to form a network structure, which then freely polymerizes with organic acids containing carbon-carbon double bonds or their derivatives to form a three-dimensional interpenetrating network structure. This effectively suppresses the volume expansion of silicon-based anode materials during charge and discharge, thereby improving the cycle performance of the battery.

[0014] Moreover, since polysaccharides or their derivatives contain abundant hydroxyl groups, a large number of hydroxyl groups remain after reacting with isocyanate groups. These hydroxyl groups, in combination with carboxyl groups in organic acids, can not only improve the water solubility and adhesion of waterborne polyurethane binders, but also form a large number of hydrogen bonds with amino groups (-NH-) in polyurethane segments. This allows water-soluble polyurethane binders to better adapt to volume changes while suppressing the volume expansion of the negative electrode material, thereby significantly improving the stability of the electrolytic structure.

[0015] In addition, the polysaccharide or its derivative-modified polyurethane prepolymer is obtained by reacting polysaccharide or its derivative with isocyanate-terminated polyurethane prepolymer through the reaction of hydroxyl groups and isocyanate groups.

[0016] The isocyanate-terminated polyurethane prepolymer can be a polyurethane prepolymer with one end of the molecular chain terminated by isocyanate, or a polyurethane prepolymer with both ends of the molecule terminated by isocyanate. Specifically, the polysaccharide-modified polyurethane prepolymer or its derivative is obtained by reacting the polysaccharide or its derivative with an isocyanate-terminated (-N=C=O) polyurethane prepolymer.

[0017] Optionally, the temperature of the above free radical polymerization reaction is 70-85℃ and the time is 2-4h; specifically, the temperature can be 72℃, 74℃, 76℃, 78℃, 80℃, 82℃ or 84℃, and the time can be 2.5h, 3h or 3.5h.

[0018] Optionally, the polysaccharide-modified polyurethane prepolymer is obtained by reacting the polysaccharide or its derivative with an isocyanate-terminated polyurethane prepolymer at 60–75°C for 2–5 h.

[0019] Specifically, the above-mentioned isocyanate-terminated polyurethane prepolymer can be prepared by the following method:

[0020] In an inert gas atmosphere, diisocyanate and polyether polyol are reacted at 60–75°C for 2–5 hours to obtain isocyanate-terminated polyurethane prepolymer.

[0021] The molar ratio of isocyanate groups to hydroxyl groups in the above diisocyanate is >1, to ensure that an excess of isocyanate groups forms an isocyanate-terminated polyurethane prepolymer.

[0022] Optionally, the polyether polyol is polypropylene glycol and / or polytetrahydrofuran glycol, and the molecular weight of the polyether polyol is 1000-3000 g / mol, specifically 1500 g / mol, 2000 g / mol or 2500 g / mol.

[0023] Optionally, the molar mass ratio of the diisocyanate, polyether polyol, polysaccharide or its derivative, to the organic acid containing carbon-carbon double bonds is (0.007-0.015) mol: (0.007-0.015) mol: (10-20) g: (0.03-0.07) mol.

[0024] Specifically, the diisocyanate can be 0.008 mol, 0.009 mol, 0.01 mol, 0.011 mol, 0.012 mol, 0.013 mol, or 0.014 mol; the polyether polyol can be 0.008 mol, 0.009 mol, 0.01 mol, 0.011 mol, 0.012 mol, 0.013 mol, or 0.014 mol; the polysaccharide or its derivative can be 11 g, 12 g, 13 g, 14 g, 15 g, 16 g, 17 g, 18 g, or 19 g; and the organic acid containing carbon-carbon double bonds can be 0.04 mol, 0.05 mol, or 0.06 mol.

[0025] Specifically, the polysaccharide or its derivative is at least one selected from guar gum, sodium carboxymethyl cellulose, hydroxymethyl cellulose, mannan, chitosan, or carrageenan. Optionally, the molecular weight of the polysaccharide or its derivative is 1000–3000 g / mol, specifically 1000 g / mol, 1500 g / mol, 2000 g / mol, or 2500 g / mol.

[0026] It should also be noted that the molecular weights of the aforementioned polyether polyols, polysaccharides, or their derivatives are generally number-average molecular weights as understood by those skilled in the art.

[0027] Optionally, the organic acid containing a carbon-carbon double bond or its derivative is at least one of 2-acrylamido-2-methylpropanesulfonic acid, sodium allyl sulfonate, 3-methacrylic acid sulfonate, styrene sulfonic acid, allyl vinyl sulfonate, 2-methyl-2-propene-1-sulfonic acid, acrylic acid, methacrylic acid, 2-hydroxy-3-phenoxypropyl (meth)acrylic acid, 3-hydroxy-1-adamantyl (meth)acrylic acid, 1,4-cyclohexanediol mono (meth)acrylic acid, glycerol monomethacrylate, triallyl phosphate, 3-sulfonate propyl methacrylic acid, diphenyl-2-(meth)acryloyloxyethyl phosphate, dibutyl-2-(meth)acryloyloxyethyl phosphate, 2-methacryloyloxyethyl phosphate, or monomethyl-2-(meth)acryloyloxyethyl phosphate.

[0028] Specifically, the isocyanate is one or more of toluene diisocyanate, 4,4'-methylene bis(phenyl isocyanate), dicyclohexylmethane diisocyanate, hexamethylene diisocyanate, 4,4-diisocyanate dicyclohexylmethane, isophorone diisocyanate, bio-based 1,5-pentane diisocyanate, or bio-based L-lysine diisocyanate; the polyol is one or more of polypropylene oxide glycol (PPG), polytetrahydrofuran glycol (PTMG), or tetrahydrofuran-propylene oxide copolydiol.

[0029] In addition, the initiator in the above preparation method is one or more of cerium ammonium nitrate, potassium persulfate, potassium permanganate, or ammonium persulfate; the mass fraction of the initiator relative to the polymer monomer is 0.1% to 5%.

[0030] A waterborne polyurethane adhesive prepared by the above method is also within the scope of protection of this invention.

[0031] This invention also protects the application of the above-mentioned waterborne polyurethane adhesive in new energy batteries.

[0032] This invention protects a negative electrode slurry comprising the aforementioned aqueous polyurethane binder, active material, and conductive agent. Specifically, the conductive agent is one or more of single-walled carbon nanotubes, graphene, conductive graphite, conductive carbon black, Ketjen black, or carbon fiber; the active material is a silicon-based material, or a mixture of carbon-based and silicon-based materials; the silicon-based material is monocrystalline silicon or silicon oxide.

[0033] The present invention also protects a negative electrode sheet comprising a current collector and a negative electrode material coated on at least one side of the current collector, the negative electrode material being obtained by drying the aforementioned negative electrode slurry.

[0034] Furthermore, this invention also protects a lithium-ion or sodium-ion battery comprising a positive electrode, an electrolyte, and the aforementioned negative electrode.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] This invention utilizes the reaction of hydroxyl groups in polysaccharides or their derivatives with isocyanate groups in polyurethane prepolymers to form a modified polyurethane prepolymer with a network structure. Under the action of an initiator, organic acids containing carbon-carbon double bonds or their derivatives undergo free polymerization with the modified polyurethane prepolymer to form an aqueous polyurethane binder with a rich cross-linked structure. The combination of isocyanate hard segments and polyether polyol soft segments in the polyurethane prepolymer forms a supporting skeleton that provides the necessary mechanical properties, toughness, and elasticity. Simultaneously, the reaction of hydroxyl groups in polysaccharides or their derivatives with isocyanate groups connects different polyurethane prepolymer segments to form a network structure, which then freely polymerizes with organic acids containing carbon-carbon double bonds or their derivatives to form a three-dimensional interpenetrating network structure. This effectively suppresses the volume expansion of silicon-based anode materials during charge and discharge, thereby improving the cycle performance of the battery. Attached Figure Description

[0037] Figure 1 The rate performance of coin cells assembled using the negative electrode sheets prepared with the binder in Examples 5 and 6 of the present invention and Comparative Example 1 is shown. Detailed Implementation

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field.

[0039] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0040] Polypropylene glycol, with a molecular weight of 2000 g / mol, is commercially available.

[0041] Polytetrahydrofuran diol, with a molecular weight of 2000 g / mol, is commercially available.

[0042] Chitosan, with a molecular weight of 1000 g / mol, is commercially available.

[0043] Guar gum, with a molecular weight of 2000 g / mol, is commercially available.

[0044] Carrageenan, with a molecular weight of 2000 g / mol, is commercially available.

[0045] Example 1

[0046] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0047] S1. Mix 0.011 mol of 4,4'-methylenebis(phenyl isocyanate) with 0.01 mol of polyoxypropylene glycol and react at 70°C for 3 h in a nitrogen atmosphere to obtain prepolymer 1;

[0048] S2. Prepolymer 1 from S1 is mixed with 10g of chitosan and reacted at 70°C for 3h under a nitrogen atmosphere to obtain prepolymer 2.

[0049] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol sodium allyl sulfonate from S2, react them at 80°C for 3 hours in a nitrogen atmosphere to obtain the waterborne polyurethane adhesive.

[0050] Example 2

[0051] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0052] S1. Mix 0.011 mol of 4,4'-methylenebis(phenyl isocyanate) with 0.01 mol of polyoxypropylene glycol and react at 60°C for 5 h in a nitrogen atmosphere to obtain prepolymer 1;

[0053] S2. Prepolymer 1 from S1 is mixed with 20g of carrageenan and reacted at 75°C for 2h in a nitrogen atmosphere to obtain prepolymer 2.

[0054] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol sodium allyl sulfonate from S2, react them at 70°C for 5 hours in a nitrogen atmosphere to obtain the waterborne polyurethane adhesive.

[0055] Example 3

[0056] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0057] S1. Mix 0.011 mol of 4,4'-methylenebis(phenyl isocyanate) with 0.01 mol of polyoxypropylene glycol and react at 75°C for 2 h in a nitrogen atmosphere to obtain prepolymer 1;

[0058] S2. Prepolymer 1 from S1 is mixed with 20g of guar gum and reacted at 60°C for 5h in a nitrogen atmosphere to obtain prepolymer 2.

[0059] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol sodium allyl sulfonate from S2, react them at 85°C for 2 hours in a nitrogen atmosphere to obtain the water-based polyurethane adhesive.

[0060] Example 4

[0061] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0062] S1. Mix 0.011 mol of 4,4-diisocyanate dicyclohexylmethane with 0.01 mol of polyoxypropylene glycol and react at 70°C for 3 h under a nitrogen atmosphere to obtain prepolymer 1;

[0063] S2. Prepolymer 1 from S1 is mixed with 20g of guar gum and reacted at 70°C for 3h in a nitrogen atmosphere to obtain prepolymer 2.

[0064] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol of acrylic acid in S2, react them in a nitrogen atmosphere at 80°C for 3 hours to obtain the water-based polyurethane adhesive.

[0065] Example 5

[0066] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0067] S1. Mix 0.011 mol toluene diisocyanate with 0.01 mol polytetrahydrofuran diol and react at 70°C for 3 h in a nitrogen atmosphere to obtain prepolymer 1;

[0068] S2. Prepolymer 1 from S1 is mixed with 20g of guar gum and reacted at 70°C for 3h in a nitrogen atmosphere to obtain prepolymer 2.

[0069] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol of acrylic acid in S2, react them in a nitrogen atmosphere at 80°C for 3 hours to obtain the water-based polyurethane adhesive.

[0070] Example 6

[0071] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0072] S1. Mix 0.011 mol isophorone diisocyanate with 0.01 mol polytetrahydrofuran diol and react at 70°C for 3 h in a nitrogen atmosphere to obtain prepolymer 1;

[0073] S2. Prepolymer 1 from S1 is mixed with 20g of guar gum and reacted at 70°C for 3h in a nitrogen atmosphere to obtain prepolymer 2.

[0074] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol sodium allyl sulfonate from S2, react them at 80°C for 3 hours in a nitrogen atmosphere to obtain the waterborne polyurethane adhesive.

[0075] Example 7

[0076] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0077] S1. Mix 0.011 mol hexamethylene diisocyanate with 0.01 mol polytetrahydrofuran glycol and react at 70°C for 3 h under a nitrogen atmosphere to obtain prepolymer 1;

[0078] S2. Prepolymer 1 from S1 is mixed with 20g of guar gum and reacted at 70°C for 3h in a nitrogen atmosphere to obtain prepolymer 2.

[0079] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol of acrylic acid in S2, react them in a nitrogen atmosphere at 80°C for 3 hours to obtain the water-based polyurethane adhesive.

[0080] Example 8

[0081] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0082] S1. Mix 0.011 mol isophorone diisocyanate with 0.01 mol polytetrahydrofuran diol and react at 70°C for 3 h in a nitrogen atmosphere to obtain prepolymer 1;

[0083] S2. Prepolymer 1 from S1 is mixed with 20g of guar gum and reacted at 70°C for 3h in a nitrogen atmosphere to obtain prepolymer 2.

[0084] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol 2-acrylamido-2-methylpropanesulfonic acid from S2, react them at 80°C for 3 hours in a nitrogen atmosphere to obtain the waterborne polyurethane adhesive.

[0085] Example 9

[0086] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0087] S1. Mix 0.011 mol of dicyclohexylmethane diisocyanate with 0.01 mol of polyoxypropylene glycol and react at 70°C for 3 h in a nitrogen atmosphere to obtain prepolymer 1;

[0088] S2. Prepolymer 1 from S1 is mixed with 20g of guar gum and reacted at 70°C for 3h in a nitrogen atmosphere to obtain prepolymer 2.

[0089] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol of 3-hydroxy-1-adamantyl (meth)acrylic acid from S2, react them at 80°C for 3 hours in a nitrogen atmosphere to obtain the waterborne polyurethane adhesive.

[0090] Comparative Example 1

[0091] A composite adhesive is obtained by mixing CMC adhesive and SBR adhesive in a mass ratio of 1:1.

[0092] Comparative Example 2

[0093] A method for preparing a waterborne polyurethane adhesive includes the following steps:

[0094] S1. Mix 0.011 mol of 4,4'-methylenebis(phenyl isocyanate) with 0.01 mol of polypropylene glycol and react at 70°C for 3 h in a nitrogen atmosphere to obtain prepolymer 1;

[0095] S2. Prepolymer 1 from S1 is mixed with 10g of hydroxyethyl methacrylate and reacted at 70°C for 3h under a nitrogen atmosphere to obtain prepolymer 2;

[0096] S3. After mixing the prepolymer 2, initiator (cerium ammonium nitrate) and 0.05 mol sodium allyl sulfonate from S2, react them at 80°C for 3 hours in a nitrogen atmosphere to obtain the waterborne polyurethane adhesive.

[0097] Performance testing

[0098] 1. Battery performance test

[0099] Negative electrode sheet: A negative electrode slurry is prepared using the binders in Examples 1-9 and Comparative Examples 1-2 as the negative electrode binder. The negative electrode slurry is then coated onto the surface of the current collector and dried to obtain the negative electrode sheet.

[0100] The specific preparation method is as follows: binder, nano-silicon, graphite and Ketjen black are mixed in a mass ratio of 3:10:90:1, and then deionized water is added and mixed evenly to form a negative electrode slurry with a solid content of 35%; then the negative electrode slurry is coated onto the surface of copper foil (thickness of 4μm), dried at 60℃ and then rolled by a roller press to obtain a negative electrode sheet.

[0101] Positive electrode sheet: using LiNi as the positive electrode active material 0.8 Co 0.1 Mn 0.1O2, conductive agent and polyvinylidene fluoride are mixed with NMP solvent in a mass ratio of 95:2.5:2.5 to form a positive electrode slurry; then the positive electrode slurry is coated onto the surface of aluminum foil, dried at 60°C and then rolled using a roller press to obtain the positive electrode sheet.

[0102] Separator: Polyolefin separator; Electrolyte: 1M LiPF6, the solvent in the electrolyte is a 1:1 volume ratio of ethylene carbonate / diethyl carbonate mixed solution.

[0103] The above-mentioned positive electrode, negative electrode, separator and electrolyte were assembled into a coin cell, and then the charge-discharge cycle performance was tested in accordance with GB / T18287-2000. The results are shown in Table 1.

[0104] 2. Electrode Expansion Rate Test

[0105] Electrode expansion rate (%) = (h - h0) / h0 × 100%;

[0106] In the above formula, h0 is the thickness (μm) of the negative electrode sheet before it is assembled into a button cell, and h is the thickness (μm) of the negative electrode sheet after 30 charge-discharge cycle tests at room temperature (25℃) and 0.2C.

[0107] 3. Peel strength test

[0108] The peel strength was tested according to the national standard GB-T2790-1995, and the results are shown in Table 1.

[0109] Table 1 Performance of each embodiment and comparative example

[0110]

[0111]

[0112] According to the data in Table 1, the batteries corresponding to the aqueous polyurethane binders in Examples 1-9 have a first-cycle discharge capacity of over 392 mAh / g and a first-cycle efficiency of over 86%. After 100 cycles at 25°C and 0.5C, the capacity retention rate is ≥87%. Simultaneously, the peel strength is over 0.60 kN / mm and the electrode expansion rate is ≤3.6%, indicating that the aqueous polyurethane binder of this invention can effectively suppress the volume expansion of silicon-based anode materials during charge and discharge, giving the battery excellent cycle stability. Furthermore, according to... Figure 1 It can be seen that, compared with the conventional negative electrode binder in Comparative Example 1, the waterborne polyurethane binders in Examples 5 and 6 have good rate performance.

[0113] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A negative electrode slurry, comprising a binder, a silicon active material, a conductive agent, and graphite, characterized in that, The method for preparing the adhesive includes the following steps: A polyurethane prepolymer modified with polysaccharides or their derivatives is mixed with at least one of organic acids or their derivatives containing carbon-carbon double bonds, and undergoes a free radical polymerization reaction under the action of an initiator to obtain an aqueous polyurethane adhesive. The polysaccharide or its derivative-modified polyurethane prepolymer is obtained by reacting polysaccharide or its derivative with isocyanate-terminated polyurethane prepolymer through the reaction of hydroxyl groups and isocyanate groups. The organic acid or its derivative is at least one of 2-acrylamido-2-methylpropanesulfonic acid, sodium allyl sulfonate, styrene sulfonic acid, allyl vinyl sulfonate, 2-methyl-2-propene-1-sulfonic acid, acrylic acid, methacrylic acid, 2-hydroxy-3-phenoxypropyl (meth)acrylic acid, 3-hydroxy-1-adamantyl (meth)acrylic acid, 1,4-cyclohexanediethanol mono (meth)acrylate, glycerol monomethacrylate, or 3-sulfonic acid propyl methacrylic acid.

2. The negative electrode slurry according to claim 1, characterized in that, The polysaccharide-modified polyurethane prepolymer is obtained by reacting the polysaccharide or its derivative with an isocyanate-terminated polyurethane prepolymer at 60-75°C for 2-5 hours.

3. The negative electrode slurry according to claim 2, characterized in that, The polysaccharide or its derivative is at least one of guar gum, sodium carboxymethyl cellulose, hydroxymethyl cellulose, mannan, chitosan or carrageenan.

4. The negative electrode slurry according to claim 1, characterized in that, The isocyanate-terminated polyurethane prepolymer was prepared by the following method: In an inert gas atmosphere, diisocyanate and polyether polyol are reacted at 60-75°C for 2-5 hours to obtain isocyanate-terminated polyurethane prepolymer.

5. The negative electrode slurry according to claim 4, characterized in that, The polyether polyol is polypropylene glycol and / or polytetrahydrofuran glycol.

6. A negative electrode sheet, comprising a current collector and a negative electrode material coated on at least one side of the current collector, characterized in that, The negative electrode material is obtained by drying the negative electrode slurry according to any one of claims 1 to 5.

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