A negative electrode sheet for a new energy battery and a method for preparing the negative electrode sheet

Abstract

The present invention discloses a negative electrode sheet for a new energy battery and a method for preparing the negative electrode sheet, belonging to the technical field of negative electrode sheet preparation. The negative electrode sheet for the new energy battery is obtained by coating a negative electrode slurry on an aluminum foil sheet and then drying it under vacuum. The negative electrode slurry is composed of the following components in parts by weight: 42-48 parts of lithium titanate, 6-10 parts of a conductive modifier, 5-12 parts of an interface stabilizer, 2-5 parts of a binder, and 1-4 parts of N-methylpyrrolidone. The negative electrode sheet prepared by this method has excellent safety, conductivity, and cycle stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of negative electrode sheet preparation, and particularly relates to a negative electrode sheet for a new energy battery and a method for preparing the negative electrode sheet. Background Art

[0002] With the urgent global demand for environmental protection and sustainable development, new energy battery technology has developed rapidly. As one of the mainstream technologies of new energy batteries, lithium-ion batteries have the advantages of high energy density, long cycle life, low self-discharge rate, no memory effect, and environmental friendliness, and are widely used in fields such as electric vehicles, portable electronic devices, and energy storage systems. However, traditional lithium-ion battery negative electrode materials, such as graphite, although having stable cycle performance and good electrical conductivity, have limitations in terms of energy density, safety, and charge and discharge rate. Especially with the rapid development under the demand of large energy storage devices such as new energy vehicles and smart power grids, the development of lithium-ion batteries with high energy density, high power density, excellent safety, and long cycle life has become a research hotspot attracting much attention in the current energy storage field.

[0003] Patent CN 106848312 A discloses a modified porous graphene, a negative electrode sheet made of the modified porous graphene, and a preparation method thereof. The modified porous graphene in this invention is obtained by surface treatment and modification with an organolithium compound of porous graphene, and then the modified porous graphene is combined with a dry electrode processing technology to make a negative electrode sheet. By controlling parameters such as the specific surface area, particle size, pore size distribution, and surface functional group content of the porous graphene, the modified porous graphene negative electrode material has the advantages of high Coulomb efficiency and high rate performance. However, there is still room for improvement in the safety, electrical conductivity, and cycle stability of the negative electrode sheet prepared by this method. Summary of the Invention

[0004] The purpose of the present invention is to provide a negative electrode sheet for a new energy battery and a method for preparing the negative electrode sheet, so as to solve the technical problems of poor safety, electrical conductivity, and cycle stability of the negative electrode sheet in the prior art.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] The present invention provides a negative electrode sheet for a new energy battery. The negative electrode sheet for the new energy battery is obtained by coating a negative electrode slurry on an aluminum foil sheet and then performing vacuum drying. The negative electrode slurry is composed of the following components in parts by weight: 42-48 parts of lithium titanate, 6-10 parts of a conductive modifier, 5-12 parts of an interfacial stabilizer, 2-5 parts of a binder, and 1-4 parts of N-methylpyrrolidone. Among them, the conductive modifier is prepared from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 4,4'-diaminodiphenyl ether, hydroxyl-terminated polycaprolactone, diphenylmethane diisocyanate, isophthalic dihydrazide, acrylic acid, and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate. The interfacial stabilizer is prepared from cyanuric chloride, diethylamine, 4,7-dichloroquinoline, and 2-methylpiperazine. The binder is composed of one or more of polyvinylidene fluoride, sodium polyacrylate, sodium alginate, and sodium carboxymethylcellulose.

[0007] Preferably, the preparation method of the conductive modifier includes the following steps:

[0008] Q1: Add 4,4'-(hexafluoroisopropylidene) diphthalic anhydride to a container containing N,N-dimethylacetamide, stir to dissolve it, and then slowly drop it into an N,N-dimethylacetamide solution containing 4,4'-diaminodiphenyl ether. After reacting in an ice bath and then stirring at room temperature, a light yellow liquid is obtained after the reaction ends.

[0009] Q2: Add hydroxyl-terminated polycaprolactone to N,N-dimethylacetamide, heat it under a nitrogen atmosphere, then add diphenylmethane diisocyanate and dibutyltin dilaurate, react to obtain a prepolymer, and then add isophthalic dihydrazide to the prepolymer and react under a nitrogen atmosphere. After the reaction ends, a high molecular substance is obtained.

[0010] Q3: Add acrylic acid to distilled water, stir, then add ammonium persulfate and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, stir evenly, add sodium sulfite, and heat to react to obtain a gel.

[0011] Q4: Add terephthalaldehyde to N,N-dimethylacetamide, add the light yellow liquid and the high molecular substance under stirring conditions, heat and stir to obtain a mixed solution, and stir and mix the mixed solution with the gel to obtain the conductive modifier.

[0012] In the above process, first, an amino-terminated polyamic acid is prepared using 4,4'-(hexafluoroisopropylidene)diphthalic anhydride and 4,4'-diaminodiphenyl ether. Subsequently, a polyurethane-urea is prepared using a hydroxyl-terminated polycaprolactone, diphenylmethane diisocyanate, and isophthalic dihydrazide as raw materials. Then, based on acrylic acid, doped with poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, and using an ammonium persulfate-sodium sulfite redox initiation system, a gel is prepared. A polyamic acid chain segment is introduced into the polyurethane-urea with a polycaprolactone main chain. The rigid polyamic acid chain segments aggregate to form a rigid hard phase structure, and further cross-link the hydrogen bond array-crosslinked polycaprolactone chain segments to form a double-crosslinked reversible crosslinked body. Then, the conductive gel is incorporated into the reversible crosslinked body to obtain a conductive modifier.

[0013] Preferably, in Q1, the molar ratio of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride to 4,4'-diaminodiphenyl ether is (0.25 - 0.5):(0.3 - 0.6), the ice bath reaction time is 4 - 6 h, and the stirring reaction time is 10 - 12 h; in Q2, the average molecular weight of the hydroxyl-terminated polycaprolactone is 2000 Da, and the molar ratio of the hydroxyl-terminated polycaprolactone, diphenylmethane diisocyanate, dibutyltin dilaurate, and isophthalic dihydrazide is (0.5 - 1):(1 - 2):(0.016 - 0.02):(0.62 - 1.25), the heating temperature is 80 - 90 °C, the reaction time is 20 - 24 h, and the reaction time under a nitrogen atmosphere is 22 - 24 h.

[0014] Preferably, in Q3, the dosage ratio of acrylic acid, distilled water, ammonium persulfate, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, and sodium sulfite is (6 - 10) mL:(20 - 25) mL:(0.025 - 0.03) g:(0.4 - 0.6) mL:(0.092 - 0.128) g, the heating reaction temperature is 40 - 50 °C, and the time is 10 - 15 min; in Q4, the dosage ratio of terephthalaldehyde, N,N-dimethylacetamide, light yellow liquid, high molecular substance, and gel is (0.32 - 0.64) g:(25 - 50) mL:(1.4 - 2.8) g:(12.9 - 25.8) g:(0.3 - 0.5) g, the heating and stirring temperature is 90 - 110 °C, the stirring time is 10 - 12 h, and the stirring and mixing time is 2 - 3 h.

[0015] Preferably, the preparation method of the interface stabilizer includes the following steps:

[0016] S1: Add cyanuric chloride to a container containing tetrahydrofuran, stir to dissolve. After dissolving diethylamine in tetrahydrofuran, slowly add it dropwise to the container. After stirring and mixing, add potassium carbonate, react at low temperature, add distilled water to quench the reaction, extract, dry, and purify to obtain Intermediate 1;

[0017] S2: Add 4,7-dichloroquinoline and 2-methylpiperazine to absolute ethanol, stir to dissolve, then heat under reflux. After the reflux ends, distill under reduced pressure and purify to obtain Intermediate 2;

[0018] S3: Add Intermediate 2 to 1,4-dioxane, mix evenly, then add potassium carbonate and Intermediate 1, stir at room temperature, filter, distill under reduced pressure, and purify to obtain the interfacial stabilizer.

[0019] In the above process, the synthesis reaction formula of the interfacial stabilizer is as follows:

[0020]

[0021] The results of mass spectrometry analysis of Intermediate 1 are: m / z: 220.03 (100.0%), 222.03 (64.3%), 224.02(10.2%), 221.03 (9.2%), 223.03 (4.9%); The results of mass spectrometry analysis of Intermediate 2 are: m / z: 261.10(100.0%), 263.10 (32.1%), 262.11 (15.3%), 264.10 (5.2%), 262.10 (1.1%),263.11 (1.1%); The results of mass spectrometry analysis of the interfacial stabilizer are: m / z: 445.15 (100.0%), 447.15(64.0%), 446.16 (23.0%), 448.16 (14.9%), 449.15 (10.6%), 447.16 (3.1%),450.15 (2.6%), 446.15 (2.6%), 448.15 (1.7%), 449.16 (1.6%).

[0022] Preferably, in S1, the dosage ratio of cyanuric chloride, diethylamine and potassium carbonate is 1 g:(0.438 - 0.53) g:(1.8 - 2.1) g, the low-temperature reaction temperature is -10 to -15 °C, the time is 1 - 2 h, extract with ethyl acetate, and dry with anhydrous magnesium sulfate.

[0023] Preferably, in S2, the dosage ratio of 4,7-dichloroquinoline, 2-methylpiperazine and absolute ethanol is 1 g : (10 - 12.5) g : (20 - 25) mL, the heating reflux temperature is 70 - 80 °C, the time is 5 - 7 h, silica gel powder is added for purification, and the eluent is a mixed solution of dichloromethane and methanol with a volume ratio of 10 : 1.

[0024] Preferably, in S3, the molar ratio of intermediate 2, 1,4-dioxane and intermediate 1 is (0.8 - 1.2) : (0.8 - 1.2) : (0.9 - 1.2), the stirring time at room temperature is 12 - 16 h, silica gel powder is added for purification, and the eluent is a mixed solution of ethyl acetate and petroleum ether with a volume ratio of 5 : 1.

[0025] Preferably, the method for preparing the negative electrode sheet for a new energy battery includes the following steps:

[0026] Step 1: Add a binder to N-methylpyrrolidone, then add lithium titanate, after magnetic stirring, add a conductive modifier and an interface stabilizer, and continue magnetic stirring to obtain a negative electrode slurry;

[0027] Step 2: Uniformly coat the negative electrode slurry on aluminum foil, and after vacuum drying, obtain a negative electrode sheet.

[0028] Preferably, in Step 1, the magnetic stirring time is 3 - 5 h, and the continuous magnetic stirring time is 10 - 12 h; in Step 2, the vacuum drying temperature is 80 - 90 °C, the vacuum degree is 0.1 - 0.2 MPa, and the drying time is 10 - 12 h.

[0029] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0030] 1. The present invention first uses 4,4'-(hexafluoroisopropylidene) diphthalic anhydride, 4,4'-diaminodiphenyl ether, hydroxyl-terminated polycaprolactone, diphenylmethane diisocyanate, isophthalic dihydrazide, acrylic acid and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate as raw materials to prepare a conductive modifier, and then uses cyanuric chloride, diethylamine, 4,7-dichloroquinoline and 2-methylpiperazine as raw materials to prepare an interface stabilizer. During the preparation process of the negative electrode sheet, adding the conductive modifier can make lithium titanate have high conductivity while having safety performance, and the addition of the interface stabilizer can provide rich ion transport channels, improve the current density and cycle time of the battery, and improve the service life of the battery.

[0031] 2. By adding a conductive modifier during the preparation process of the electrode sheet, the present invention can effectively improve the conductivity, structural stability, and electrochemical performance of the negative electrode sheet. The poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate introduced in the conductive modifier can construct an efficient conductive network in the negative electrode sheet, enabling electrons to migrate rapidly, significantly reducing the resistance and minimizing battery polarization. Meanwhile, the rigid polyamic acid chain segments and the cross-linked polycaprolactone chain segments together form a stable network structure, effectively withstanding the stress during the ion insertion / extraction process, slowing down the volume change of the negative electrode material, and maintaining the integrity and performance stability of the negative electrode sheet. In addition, the conductive modifier can also improve the interfacial contact between the negative electrode sheet and the electrolyte, promoting the transport, diffusion of ions, as well as the infiltration and penetration of the electrolyte, thereby reducing the ion diffusion resistance, increasing the ion utilization rate, and enhancing the cycle stability of the battery.

[0032] 3. By adding an interface stabilizer to the negative electrode sheet, the present invention can effectively improve the interfacial stability of the negative electrode sheet and simultaneously optimize the ion transport of the negative electrode sheet. The nitrogen atoms contained in the interface stabilizer can form coordination bonds or chemical bonds with the metal atoms on the surface of the negative electrode sheet, thereby enhancing the polarity of the surface of the negative electrode sheet and making the interaction between it and the electrolyte more stable. Through chemical bonding, the interface stabilizer can firmly adsorb on the surface of the negative electrode sheet, forming a dense protective layer, which can effectively prevent the erosion of harmful substances in the electrolyte to the negative electrode sheet and extend the service life of the negative electrode sheet. The presence of the interface stabilizer can also reduce the interfacial tension between the negative electrode sheet and the electrolyte, making the contact between the negative electrode sheet and the electrolyte closer and more stable, reducing unnecessary interfacial reactions and energy losses, and contributing to improving the cycle stability and safety of the battery; moreover, the interface stabilizer can improve the microscopic structure of the surface of the negative electrode sheet, form channels conducive to ion transport, reduce the ion transport resistance, making it easier for ions to diffuse and migrate inside the negative electrode sheet, and enhancing the charge-discharge rate and capacity utilization rate of the battery. Detailed implementation manners

[0033] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Apparently, the described embodiments are only a part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Example 1: This example discloses a preparation method of a conductive modifier, including the following steps:

[0035] Q1: Add 1.38 g of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride into a container containing 7.5 mL of N,N-dimethylacetamide. After stirring and dissolving, slowly drop it into a 6 mL N,N-dimethylacetamide solution containing 0.75 g of 4,4'-diaminodiphenyl ether. After reacting in an ice bath for 4 h, stir and react at room temperature for 12 h. After the reaction is completed, a light yellow liquid is obtained;

[0036] Q2: Add 3 g of hydroxyl-terminated polycaprolactone with an average molecular weight of 2000 Da into 50 mL of N,N-dimethylacetamide. Under a nitrogen atmosphere, heat at 80 °C, then add 0.75 g of diphenylmethane diisocyanate and 0.023 g of dibutyltin dilaurate. After reacting for 24 h, a prepolymer is obtained. Then add 0.36 g of isophthaloyl hydrazide into the prepolymer and react under a nitrogen atmosphere for 24 h. After the reaction is completed, a high molecular substance is obtained;

[0037] Q3: Add 8 mL of acrylic acid into 22.5 mL of distilled water and stir. Then add 0.027 g of ammonium persulfate and 0.5 mL of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate. After stirring evenly, add 0.11 g of sodium sulfite and heat and react at 45 °C for 15 min to obtain a gel;

[0038] Q4: Add 0.48 g of terephthalaldehyde into 35 mL of N,N-dimethylacetamide. Under stirring conditions, add 2.1 g of the light yellow liquid and 19.5 g of the high molecular substance. After heating and stirring at 100 °C for 12 h, a mixed solution is obtained. Mix the mixed solution with 0.4 g of the gel and stir for 2 h to obtain a conductive modifier.

[0039] This example discloses a preparation method of an interfacial stabilizer, including the following steps:

[0040] S1: Add 1 g of cyanuric chloride into a container containing 20 mL of tetrahydrofuran, stir and dissolve. After dissolving 0.48 g of diethylamine in 20 mL of tetrahydrofuran, slowly drop it into the container. After stirring and mixing, add 1.95 g of potassium carbonate and react at -10 °C for 2 h. Add distilled water to quench the reaction, extract with ethyl acetate, dry with anhydrous magnesium sulfate, and purify to obtain intermediate 1;

[0041] S2: Add 1 g of 4,7-dichloroquinoline and 11 g of 2-methylpiperazine into 22.5 mL of absolute ethanol, stir and dissolve. After that, heat and reflux at 80 °C for 6 h. After the reflux is completed, distill under reduced pressure, add silica gel powder and then purify. The eluent is a mixed solution of dichloromethane and methanol with a volume ratio of 10:1 to obtain intermediate 2;

[0042] S3: Add 1.32 g of intermediate 2 to 0.47 g of 1,4-dioxane. After mixing evenly, add 0.65 g of potassium carbonate and 0.9 g of intermediate 1. Stir at room temperature for 16 h, filter, distill under reduced pressure, add silica gel powder and then purify. The eluent is a mixed solution of ethyl acetate and petroleum ether with a volume ratio of 5:1 to obtain an interface stabilizer.

[0043] This example discloses a negative electrode sheet for a new energy battery. The negative electrode sheet for a new energy battery is obtained by coating a negative electrode slurry on an aluminum foil sheet and drying it under vacuum. The negative electrode slurry is composed of the following components in parts by weight: 45 parts of lithium titanate, 8 parts of a conductive modifier, 8.5 parts of an interface stabilizer, 3.5 parts of polyvinylidene fluoride, and 2.5 parts of N-methylpyrrolidone.

[0044] This example discloses a preparation method for a negative electrode sheet for a new energy battery, including the following steps:

[0045] Step 1: Add polyvinylidene fluoride to N-methylpyrrolidone, and then add lithium titanate. After magnetic stirring for 5 h, add a conductive modifier and an interface stabilizer, and continue magnetic stirring for 12 h to obtain a negative electrode slurry.

[0046] Step 2: Uniformly coat the negative electrode slurry on the aluminum foil, and after vacuum drying at 80 °C and 0.2 MPa for 12 h, obtain a negative electrode sheet.

[0047] Example 2: This example discloses a preparation method for a conductive modifier, including the following steps:

[0048] Q1: Add 0.93 g of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride to a container containing 7.5 mL of N,N-dimethylacetamide. After stirring and dissolving, slowly drop it into a 6 mL N,N-dimethylacetamide solution containing 0.5 g of 4,4'-diaminodiphenyl ether. After reacting in an ice bath for 4 h, stir at room temperature for 12 h. After the reaction ends, obtain a light yellow liquid.

[0049] Q2: Add 2 g of hydroxyl-terminated polycaprolactone with an average molecular weight of 2000 Da to 50 mL of N,N-dimethylacetamide. Heat at 80 °C under a nitrogen atmosphere, then add 1 g of diphenylmethane diisocyanate and 0.025 g of dibutyltin dilaurate, react for 24 h to obtain a prepolymer, and then add 0.24 g of isophthaloyl hydrazide to the prepolymer and react for 24 h under a nitrogen atmosphere. After the reaction ends, obtain a high molecular substance.

[0050] Q3: Add 6 mL of acrylic acid to 20 mL of distilled water, stir, then add 0.025 g of ammonium persulfate and 0.4 mL of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate. After stirring evenly, add 0.092 g of sodium sulfite, and react at 45 °C for 15 min to obtain a gel.

[0051] Q4: Add 0.32 g of terephthalaldehyde to 25 mL of N,N-dimethylacetamide. Under stirring conditions, add 1.4 g of a light yellow liquid and 12.9 g of a high molecular substance. After heating and stirring at 100 °C for 12 h, a mixed solution is obtained. Stir and mix the mixed solution with 0.3 g of the gel for 2 h to obtain a conductive modifier.

[0052] This example discloses a preparation method of an interface stabilizer, including the following steps:

[0053] S1: Add 1 g of cyanuric chloride to a container containing 20 mL of tetrahydrofuran, stir to dissolve. After dissolving 0.438 g of diethylamine in 20 mL of tetrahydrofuran, slowly drop it into the container. After stirring and mixing, add 1.8 g of potassium carbonate, react at -10 °C for 2 h, add distilled water to quench the reaction, extract with ethyl acetate, dry with anhydrous magnesium sulfate, and purify to obtain intermediate 1.

[0054] S2: Add 1 g of 4,7-dichloroquinoline and 10 g of 2-methylpiperazine to 25 mL of absolute ethanol, stir to dissolve, then heat and reflux at 80 °C for 6 h. After the reflux ends, perform vacuum distillation, add silica gel powder and then purify. The eluent is a mixed solution of dichloromethane and methanol with a volume ratio of 10:1 to obtain intermediate 2.

[0055] S3: Add 1.05 g of intermediate 2 to 0.38 g of 1,4-dioxane, mix evenly, then add 0.65 g of potassium carbonate and 0.75 g of intermediate 1, stir at room temperature for 16 h, filter, perform vacuum distillation, add silica gel powder and then purify. The eluent is a mixed solution of ethyl acetate and petroleum ether with a volume ratio of 5:1 to obtain the interface stabilizer.

[0056] This example discloses a negative electrode sheet for a new energy battery. The negative electrode sheet for a new energy battery is obtained by coating negative electrode slurry on an aluminum foil sheet and then vacuum drying. The negative electrode slurry is composed of the following components in parts by weight: 42 parts of lithium titanate, 6 parts of conductive modifier, 5 parts of interface stabilizer, 2 parts of polyvinylidene fluoride, and 1 part of N-methylpyrrolidone.

[0057] This example discloses a preparation method of a negative electrode sheet for a new energy battery, including the following steps:

[0058] Step 1: Add polyvinylidene fluoride to N-methylpyrrolidone, then add lithium titanate. After magnetic stirring for 5 h, add a conductive modifier and an interfacial stabilizer, and continue magnetic stirring for 12 h to obtain a negative electrode paste.

[0059] Step 2: Uniformly coat the negative electrode paste on aluminum foil, and after vacuum drying at 80 °C and 0.2 MPa for 12 h, obtain a negative electrode sheet.

[0060] Example 3: This example discloses a preparation method of a conductive modifier, which includes the following steps:

[0061] Q1: Add 1.85 g of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride to a container containing 7.5 mL of N,N-dimethylacetamide. After stirring and dissolving, slowly drop it into a 6 mL N,N-dimethylacetamide solution containing 1 g of 4,4'-diaminodiphenyl ether. After reacting in an ice bath for 4 h, stir and react at room temperature for 12 h. After the reaction ends, obtain a light yellow liquid.

[0062] Q2: Add 4 g of hydroxyl-terminated polycaprolactone with an average molecular weight of 2000 Da to 50 mL of N,N-dimethylacetamide. Under a nitrogen atmosphere, heat at 80 °C, then add 0.5 g of diphenylmethane diisocyanate and 0.02 g of dibutyltin dilaurate, react for 24 h to obtain a prepolymer, and then add 0.49 g of isophthaloyl hydrazide to the prepolymer, and react under a nitrogen atmosphere for 24 h. After the reaction ends, obtain a high molecular substance.

[0063] Q3: Add 10 mL of acrylic acid to 25 mL of distilled water, stir, then add 0.03 g of ammonium persulfate and 0.6 mL of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate. After stirring evenly, add 0.128 g of sodium sulfite, and heat and react at 45 °C for 15 min to obtain a gel.

[0064] Q4: Add 0.64 g of terephthalaldehyde to 50 mL of N,N-dimethylacetamide, add 2.8 g of the light yellow liquid and 25.8 g of the high molecular substance under stirring conditions, heat and stir at 100 °C for 12 h to obtain a mixed solution, and stir and mix the mixed solution with 0.5 g of the gel for 2 h to obtain a conductive modifier.

[0065] This example discloses a preparation method of an interfacial stabilizer, which includes the following steps:

[0066] S1: Add 1 g of cyanuric chloride to a container containing 20 mL of tetrahydrofuran, stir to dissolve. After dissolving 0.53 g of diethylamine in 20 mL of tetrahydrofuran, slowly add it dropwise to the container. After stirring and mixing, add 2.1 g of potassium carbonate, react at -10 °C for 2 h, add distilled water to quench the reaction, extract with ethyl acetate, dry with anhydrous magnesium sulfate, and purify to obtain Intermediate 1;

[0067] S2: Add 1 g of 4,7-dichloroquinoline and 12 g of 2-methylpiperazine to 20 mL of absolute ethanol, stir to dissolve, heat under reflux at 80 °C for 6 h. After the reflux ends, perform vacuum distillation, add silica gel powder and then purify. The eluent is a mixed solution of dichloromethane and methanol with a volume ratio of 10:1 to obtain Intermediate 2;

[0068] S3: Add 1.57 g of Intermediate 2 to 0.56 g of 1,4-dioxane, mix evenly, add 0.65 g of potassium carbonate and 1 g of Intermediate 1, stir at room temperature for 16 h, filter, perform vacuum distillation, add silica gel powder and then purify. The eluent is a mixed solution of ethyl acetate and petroleum ether with a volume ratio of 5:1 to obtain the interfacial stabilizer.

[0069] This example discloses a negative electrode sheet for a new energy battery. The negative electrode sheet for the new energy battery is obtained by coating a negative electrode paste on an aluminum foil sheet and then vacuum drying. The negative electrode paste is composed of the following components in parts by weight: 48 parts of lithium titanate, 10 parts of a conductive modifier, 12 parts of an interfacial stabilizer, 5 parts of polyvinylidene fluoride, and 4 parts of N-methylpyrrolidone.

[0070] This example discloses a preparation method for a negative electrode sheet for a new energy battery, including the following steps:

[0071] Step 1: Add polyvinylidene fluoride to N-methylpyrrolidone, then add lithium titanate. After magnetic stirring for 5 h, add a conductive modifier and an interfacial stabilizer, and continue magnetic stirring for 12 h to obtain a negative electrode paste;

[0072] Step 2: Uniformly coat the negative electrode paste on the aluminum foil, and after vacuum drying at 80 °C and 0.2 MPa for 12 h, obtain the negative electrode sheet.

[0073] Example 4: This example discloses a preparation method for a conductive modifier, including the following steps:

[0074] Q1: Add 1.15 g of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride to a container containing 7.5 mL of N,N-dimethylacetamide, stir to dissolve and then slowly add it dropwise to a 6 mL N,N-dimethylacetamide solution containing 0.6 g of 4,4'-diaminodiphenyl ether. After reacting in an ice bath for 4 h, stir at room temperature for 12 h. After the reaction ends, obtain a light yellow liquid;

[0075] Q2: Add 2.5 g of hydroxyl-terminated polycaprolactone with an average molecular weight of 2000 Da to 50 mL of N,N-dimethylacetamide. Under a nitrogen atmosphere, heat at 80 °C, then add 0.6 g of diphenylmethane diisocyanate and 0.021 g of dibutyltin dilaurate. After reacting for 24 h, a prepolymer is obtained. Then add 0.28 g of isophthaloyl hydrazide to the prepolymer and react for 24 h under a nitrogen atmosphere. After the reaction is completed, a high-molecular substance is obtained;

[0076] Q3: Add 7 mL of acrylic acid to 22 mL of distilled water, stir, then add 0.026 g of ammonium persulfate and 0.45 mL of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate. After stirring evenly, add 0.098 g of sodium sulfite and heat at 45 °C for 15 min to obtain a gel;

[0077] Q4: Add 0.4 g of terephthalaldehyde to 28 mL of N,N-dimethylacetamide, add 1.8 g of a light yellow liquid and 14.2 g of the high-molecular substance under stirring conditions, heat and stir at 100 °C for 12 h to obtain a mixed solution. Stir and mix the mixed solution with 0.35 g of the gel for 2 h to obtain a conductive modifier.

[0078] This example discloses a preparation method of an interface stabilizer, including the following steps:

[0079] S1: Add 1 g of cyanuric chloride to a container containing 20 mL of tetrahydrofuran, stir to dissolve. After dissolving 0.45 g of diethylamine in 20 mL of tetrahydrofuran, slowly add it dropwise to the container. After stirring and mixing, add 1.9 g of potassium carbonate, react at -10 °C for 2 h, add distilled water to quench the reaction, extract with ethyl acetate, dry with anhydrous magnesium sulfate, and purify to obtain intermediate 1;

[0080] S2: Add 1 g of 4,7-dichloroquinoline and 12.5 g of 2-methylpiperazine to 21 mL of absolute ethanol, stir to dissolve, then heat under reflux at 80 °C for 6 h. After the reflux is completed, distill under reduced pressure, add silica gel powder and then purify. The eluent is a mixed solution of dichloromethane and methanol with a volume ratio of 10:1 to obtain intermediate 2;

[0081] S3: Add 1.21 g of intermediate 2 to 0.42 g of 1,4-dioxane, mix evenly, then add 0.65 g of potassium carbonate and 0.8 g of intermediate 1, stir at room temperature for 16 h, filter, distill under reduced pressure, add silica gel powder and then purify. The eluent is a mixed solution of ethyl acetate and petroleum ether with a volume ratio of 5:1 to obtain the interface stabilizer.

[0082] This embodiment discloses a negative electrode sheet for a new energy battery. The negative electrode sheet for the new energy battery is obtained by coating a negative electrode slurry on an aluminum foil sheet and drying it under vacuum. The negative electrode slurry is composed of the following components in parts by weight: 43 parts of lithium titanate, 7 parts of a conductive modifier, 7 parts of an interfacial stabilizer, 4 parts of polyvinylidene fluoride, and 2 parts of N-methylpyrrolidone.

[0083] This embodiment discloses a preparation method for a negative electrode sheet for a new energy battery, including the following steps:

[0084] Step 1: Add polyvinylidene fluoride to N-methylpyrrolidone, then add lithium titanate. After magnetic stirring for 5 h, add the conductive modifier and the interfacial stabilizer, and continue magnetic stirring for 12 h to obtain a negative electrode slurry;

[0085] Step 2: Uniformly coat the negative electrode slurry on the aluminum foil, and after vacuum drying at 80 °C and 0.2 MPa for 12 h, obtain the negative electrode sheet.

[0086] Example 5: This embodiment discloses a preparation method for a conductive modifier, including the following steps:

[0087] Q1: Add 1.57 g of 4,4'-(hexafluoroisopropylidene) diphthalic anhydride to a container containing 7.5 mL of N,N-dimethylacetamide. After stirring and dissolving, slowly drop it into a 6 mL N,N-dimethylacetamide solution containing 0.8 g of 4,4'-diaminodiphenyl ether. After reacting in an ice bath for 4 h, stir and react at room temperature for 12 h. After the reaction ends, obtain a light yellow liquid;

[0088] Q2: Add 3.5 g of hydroxyl-terminated polycaprolactone with an average molecular weight of 2000 Da to 50 mL of N,N-dimethylacetamide. Under a nitrogen atmosphere, heat at 80 °C, then add 0.8 g of diphenylmethane diisocyanate and 0.024 g of dibutyltin dilaurate, react for 24 h to obtain a prepolymer, and then add 0.41 g of isophthalic dihydrazide to the prepolymer. React under a nitrogen atmosphere for 24 h. After the reaction ends, obtain a high molecular substance;

[0089] Q3: Add 9 mL of acrylic acid to 24 mL of distilled water, stir, then add 0.028 g of ammonium persulfate and 0.55 mL of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate. After stirring evenly, add 0.114 g of sodium sulfite, and heat and react at 45 °C for 15 min to obtain a gel;

[0090] Q4: Add 0.58 g of terephthalaldehyde to 47 mL of N,N-dimethylacetamide. Under stirring conditions, add 2.4 g of the light yellow liquid and 21.7 g of the high molecular substance. After heating and stirring at 100 °C for 12 h, obtain a mixed solution. Stir and mix the mixed solution with 0.45 g of the gel for 2 h to obtain the conductive modifier.

[0091] This embodiment discloses a preparation method of an interface stabilizer, including the following steps:

[0092] S1: Add 1 g of cyanuric chloride to a container containing 20 mL of tetrahydrofuran, stir to dissolve. After dissolving 0.51 g of diethylamine in 20 mL of tetrahydrofuran, slowly drop it into the container. After stirring and mixing, add 2 g of potassium carbonate, react at -10 °C for 2 h, add distilled water to quench the reaction, extract with ethyl acetate, dry with anhydrous magnesium sulfate, and purify to obtain intermediate 1;

[0093] S2: Add 1 g of 4,7-dichloroquinoline and 11.5 g of 2-methylpiperazine to 24 mL of absolute ethanol, stir to dissolve, heat and reflux at 80 °C for 6 h. After the reflux ends, perform vacuum distillation, add silica gel powder and then purify. The eluent is a mixed solution of dichloromethane and methanol with a volume ratio of 10:1 to obtain intermediate 2;

[0094] S3: Add 1.48 g of intermediate 2 to 0.52 g of 1,4-dioxane, mix evenly, then add 0.65 g of potassium carbonate and 0.83 g of intermediate 1, stir at room temperature for 16 h, filter, perform vacuum distillation, add silica gel powder and then purify. The eluent is a mixed solution of ethyl acetate and petroleum ether with a volume ratio of 5:1 to obtain the interface stabilizer.

[0095] This embodiment discloses a negative electrode sheet for a new energy battery. The negative electrode sheet for the new energy battery is obtained by coating a negative electrode slurry on an aluminum foil sheet and then performing vacuum drying. The negative electrode slurry is composed of the following components in parts by weight: 47 parts of lithium titanate, 9 parts of a conductive modifier, 10 parts of an interface stabilizer, 3 parts of polyvinylidene fluoride, and 3 parts of N-methylpyrrolidone.

[0096] This embodiment discloses a preparation method of a negative electrode sheet for a new energy battery, including the following steps:

[0097] Step 1: Add polyvinylidene fluoride to N-methylpyrrolidone, then add lithium titanate. After magnetic stirring for 5 h, add a conductive modifier and an interface stabilizer, and continue magnetic stirring for 12 h to obtain a negative electrode slurry;

[0098] Step 2: Uniformly coat the negative electrode slurry on the aluminum foil, and perform vacuum drying at 80 °C and 0.2 MPa for 12 h to obtain the negative electrode sheet.

[0099] Comparative Example 1: Compared with Example 1, in the process of preparing the conductive modifier in Comparative Example 1, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate is not added, and other conditions remain unchanged.

[0100] Comparative Example 2: Compared with Example 1, in the process of preparing the interfacial stabilizer in Comparative Example 2, cyanuric chloride is not added, and other conditions remain unchanged.

[0101] Comparative Example 3: Compared with Example 1, in the process of preparing the negative electrode sheet in Comparative Example 3, the conductive modifier is not added, and other conditions remain unchanged.

[0102] Comparative Example 4: Compared with Example 1, in the process of preparing the negative electrode sheet in Comparative Example 4, the interfacial stabilizer is not added, and other conditions remain unchanged.

[0103] Experimental Example: The performance of the samples was tested according to GB / T 44027.1-2024, and the test results are shown in Table 1:

[0104] Table 1

[0105] Project <![CDATA[Initial discharge specific capacity / mAh·g -1 > Initial Coulombic Efficiency / % Discharge Capacity Retention Rate / % Example 1 198.44 93.62 88.63 Example 2 197.36 93.16 88.39 Example 3 197.02 92.93 88.31 Example 4 196.86 92.44 88.11 Example 5 197.24 92.16 87.94 Comparative Example 1 185.56 88.49 81.45 Comparative Example 2 186.34 88.37 81.62 Comparative Example 3 183.17 87.64 80.29 Comparative Example 4 182.03 87.46 80.34

[0106] The initial discharge specific capacity reflects the energy storage capacity and discharge performance of the negative electrode material. A high initial discharge specific capacity means that the negative electrode material can store and release more energy during the initial charge and discharge process, improving the overall performance of the battery; the initial Coulomb efficiency reflects the internal loss situation of the battery. A high initial Coulomb efficiency means that the negative electrode material has a low internal loss during the first charge and discharge process and can more effectively use the input electrical energy for energy storage and release; the discharge capacity retention rate is used to evaluate the cycle stability and life of the negative electrode material. A high discharge capacity retention rate means that the negative electrode material can still maintain good energy storage capacity after multiple charge and discharge cycles, thus extending the service life of the battery. It can be seen from the test results in Table 1 that the negative electrode sheets prepared in Examples 1-5 of the present invention have excellent energy storage capacity, low internal loss, and excellent cycle performance. By comparing Comparative Example 1 with Examples 1-5, it can be seen that adding poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate can effectively improve the energy storage capacity and cycle performance of the negative electrode sheet and reduce the internal loss of the battery; by comparing Comparative Example 2 with Examples 1-5, it can be seen that adding cyanuric chloride can effectively improve the energy storage capacity and cycle performance of the negative electrode sheet and reduce the internal loss of the battery; by comparing Comparative Example 3 with Examples 1-5, it can be seen that adding the conductive modifier can effectively improve the energy storage capacity and cycle performance of the negative electrode sheet and reduce the internal loss of the battery; by comparing Comparative Example 4 with Examples 1-5, it can be seen that adding the interfacial stabilizer can effectively improve the energy storage capacity and cycle performance of the negative electrode sheet and reduce the internal loss of the battery.

[0107] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

[0108] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific embodiments. Obviously, according to the content of this specification, many modifications and changes can be made. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A negative electrode sheet for a new energy battery, characterized in that: The negative electrode sheet for new energy batteries is obtained by coating a negative electrode slurry on an aluminum foil and vacuum drying, wherein the negative electrode slurry is composed of the following components in parts by weight: 42-48 parts of lithium titanate, 6-10 parts of a conductive modifier, 5-12 parts of an interface stabilizer, 2-5 parts of a binder, and 1-4 parts of N-methylpyrrolidone, wherein the binder is composed of one or more of polyvinylidene fluoride, sodium polyacrylate, sodium alginate, and sodium carboxymethyl cellulose; The preparation method of the conductive modifier comprises the following steps: Q1: Add 4,4'-(hexafluoroisopropylene) diphthalic anhydride to a container containing N,N-dimethylacetamide, stir to dissolve, and then slowly add dropwise to the N,N-dimethylacetamide solution containing 4,4'-diaminodiphenyl ether. After reacting in an ice bath, stir and react at room temperature. After the reaction is completed, a light yellow liquid is obtained. Q2: Add hydroxyl-terminated polycaprolactone to N,N-dimethylacetamide, heat under nitrogen atmosphere, then add diphenylmethane diisocyanate and dibutyltin dilaurate to react to obtain a prepolymer, then add isophthalic acid hydrazide to the prepolymer, react under nitrogen atmosphere, and obtain a polymer after the reaction is completed; Q3: Add acrylic acid to distilled water, stir, then add ammonium persulfate and poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate, stir evenly, add sodium sulfite, heat and react to obtain a gel; Q4: Add terephthalaldehyde to N,N-dimethylacetamide, add light yellow liquid and polymer substance under stirring, heat and stir to obtain a mixed solution, stir and mix the mixed solution with gel to obtain a conductive modifier; The preparation method of the interface stabilizer comprises the following steps: S1: Add cyanuric chloride to a container containing tetrahydrofuran, stir to dissolve, dissolve diethylamine in tetrahydrofuran, slowly add it dropwise to the container, stir to mix, add potassium carbonate, react at low temperature, add distilled water to quench the reaction, extract, dry, and purify to obtain intermediate 1; S2: Add 4,7-dichloroquinoline and 2-methylpiperazine to anhydrous ethanol, stir to dissolve, heat to reflux, and after the reflux is completed, perform vacuum distillation and purification to obtain intermediate 2; S3: Add intermediate 2 to 1,4-dioxane, mix well, add potassium carbonate and intermediate 1, stir at room temperature, filter, distill under reduced pressure, and purify to obtain an interfacial stabilizer.

2. The negative electrode sheet for new energy batteries according to claim 1, characterized in that: In Q1, the molar ratio of 4,4'-(hexafluoroisopropylene) diphthalic anhydride and 4,4'-diaminodiphenyl ether is (0.25-0.5):(0.3-0.6), the ice bath reaction time is 4-6 hours, and the stirring reaction time is 10-12 hours; in Q2, the average molecular weight of the hydroxyl-terminated polycaprolactone is 2000Da, and the molar ratio of the hydroxyl-terminated polycaprolactone, diphenylmethane diisocyanate, dibutyltin dilaurate and isophthalic acid hydrazide is (0.5-1):(1-2):(0.016-0.02):(0.62-1.25), the heating temperature is 80-90°C, the reaction time is 20-24 hours, and the reaction time under nitrogen atmosphere is 22-24 hours.

3. The negative electrode sheet for new energy batteries according to claim 1, characterized in that: In the Q3, the usage ratio of acrylic acid, distilled water, ammonium persulfate, poly(3,4-ethylenedioxythiophene)-polystyrene sulfonate and sodium sulfite is (6-10) mL: (20-25) mL: (0.025-0.03) g: (0.4-0.6) mL: (0.092-0.128) g, the heating reaction temperature is 40-50° C., and the reaction time is 10-15 min. In the Q4, the usage ratio of terephthalaldehyde, N,N-dimethylacetamide, light yellow liquid, polymer substance and gel is (0.32-0.64) g: (25-50) mL: (1.4-2.8) g: (12.9-25.8) g: (0.3-0.5) g, the heating and stirring temperature is 90-110° C., the stirring time is 10-12 h, and the stirring and mixing time is 2-3 h.

4. The negative electrode sheet for new energy batteries according to claim 1, characterized in that: In the S1, the usage ratio of cyanuric chloride, diethylamine and potassium carbonate is 1g: (0.438-0.53)g: (1.8-2.1)g, the low-temperature reaction temperature is -10 to -15°C, the time is 1-2h, extraction is performed with ethyl acetate, and drying is performed with anhydrous magnesium sulfate.

5. The negative electrode sheet for new energy batteries according to claim 1, characterized in that: In the S2, the dosage ratio of 4,7-dichloroquinoline, 2-methylpiperazine and anhydrous ethanol is 1 g: (10-12.5) g: (20-25) mL, the heating reflux temperature is 70-80°C, the time is 5-7 h, and the purification is carried out after adding silica gel powder. The eluent is a mixed solution of dichloromethane and methanol in a volume ratio of 10:

1.

6. The negative electrode sheet for new energy batteries according to claim 1, characterized in that: In the S3, the molar ratio of intermediate 2, 1,4-dioxane and intermediate 1 is (0.8-1.2): (0.8-1.2): (0.9-1.2), the stirring time at room temperature is 12-16 hours, and purification is carried out after adding silica gel powder. The eluent is a mixed solution of ethyl acetate and petroleum ether in a volume ratio of 5:

1.

7. The method for preparing a negative electrode sheet for a new energy battery according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Add a binder to N-methylpyrrolidone, then add lithium titanate, add a conductive modifier and an interface stabilizer after magnetic stirring, and continue magnetic stirring to obtain a negative electrode slurry; Step 2: Evenly coat the negative electrode slurry on the aluminum foil and vacuum dry it to obtain a negative electrode sheet.

8. The method for preparing a negative electrode sheet for a new energy battery according to claim 7, characterized in that: In the step 1, the magnetic stirring time is 3-5 hours, and the continued magnetic stirring time is 10-12 hours; in the step 2, the vacuum drying temperature is 80-90° C., the vacuum degree is 0.1-0.2 MPa, and the drying time is 10-12 hours.

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