Negative electrode composite material, preparation method therefor, negative electrode, battery, and electrical device

Abstract

A negative electrode composite material 100, a preparation method therefor, a negative electrode, a battery, and an electrical device. The negative electrode composite material 100 comprises a negative electrode material 10 and a polymer layer 20 wrapping around the negative electrode material 10. The polymer layer 20 is made of a carboxyl group, an amide group, and a sulfonic acid group.

Description

Negative electrode composite material and preparation method thereof, negative electrode, battery and electric device

[0001] The present application claims priority to the Chinese patent application No. 202410433135.0, filed on April 10, 2024, and entitled "Negative electrode composite material and preparation method thereof, negative electrode, battery and electric device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of batteries, and more particularly, to a negative electrode composite material and a preparation method thereof, a negative electrode, a battery and an electric device. BACKGROUND

[0003] A solid electrolyte interface (SEI) film is formed by the reaction of lithium ions and liquid electrolyte and serves as an interface layer between the negative electrode and the electrolyte. The SEI film is usually fragile and uneven, and the volume change of the negative electrode material during charging and discharging will exacerbate the rupture of the SEI film, causing the SEI film to be continuously generated, consuming more lithium ions, rapidly reducing the performance of the battery, and affecting the use of the battery.

[0004] SUMMARY

[0005] Therefore, the present application provides a negative electrode composite material and a preparation method thereof, a negative electrode, a battery and an electric device.

[0006] In a first aspect, the present application provides a negative electrode composite material, comprising a negative electrode material and a polymer layer wrapping the negative electrode material, the material of the polymer layer having a carboxyl group, an amide group and a sulfonic acid group.

[0007] Optionally, the polymer layer has a material comprising a first monomer, a second monomer and a third monomer, the first monomer comprising the carboxyl group, the second monomer comprising the amide group, and the third monomer comprising the sulfonic acid group.

[0008] Optionally, the first monomer comprises acrylic acid.

[0009] Optionally, the second monomer further comprises at least one of an alkenyl group, a carboxyl group and a hydroxyl group.

[0010] Optionally, the third monomer further comprises at least one of an alkenyl group, a carboxyl group and a hydroxyl group.

[0011] Optionally, the material of the polymer layer comprises an acrylic acid-alkenyl amide-alkenyl sulfonate copolymer.

[0012] Optionally, the negative electrode material and the polymer layer have a hydrogen bond therebetween.

[0013] Further, the negative electrode material and the polymer layer have an ester bond.

[0014] Optionally, the thickness of the polymer layer is 1 nm-80 nm.

[0015] Optionally, the coating rate of the polymer layer on the negative electrode material is greater than 90%.

[0016] Optionally, the particle size D50 of the negative electrode material is 8-16 pm.

[0017] Optionally, the particle size D50 of the negative electrode composite material is 8-16.2 pm.

[0018] Optionally, the specific surface area of the negative electrode composite material is 2-4 m 2 2 / g.

[0019] Optionally, the negative electrode material includes at least one of graphite and silicon-based material.

[0020] Optionally, the mass ratio of the polymer layer to the negative electrode material in the negative electrode composite material is 0.4%-8%.

[0021] In a second aspect, the application provides a preparation method of a negative electrode composite material, comprising:

[0022] Optionally, the pre-polymer solution includes a first monomer, a second monomer, a third monomer and an initiator, the first monomer includes the carboxyl group, the second monomer includes the amide group, and the third monomer includes the sulfonic acid group.

[0023] Optionally, the pre-polymer solution includes a first monomer, a second monomer, a third monomer and an initiator, the first monomer includes the carboxyl group, the second monomer includes the amide group, and the third monomer includes the sulfonic acid group.

[0024] Further, the mass ratio of the first monomer, the second monomer and the third monomer is (1-8):(1-3):(1-4).

[0025] Further, the mass ratio of the first monomer, the second monomer and the third monomer is (1-8):(1-3):(1-4).

[0026] Further, the mass ratio of the first monomer, the second monomer and the third monomer is (1-8):(1-3):(1-4).

[0027] ​Further, the initiator includes at least one of a persulfate and an azobisimidozolinium hydrochloride.

[0028] Further, the first monomer includes acrylic acid.

[0029] Further, the second monomer includes at least one of acrylamide, N-vinylcaprolactam, N-tert-butyl acrylamide, N-octyl acrylamide, and N,N-methylenebisacrylamide.

[0030] Further, the third monomer includes at least one of an alpha-alkenyl sulfonate, an allyl sulfonate, a methacryl sulfonate, a hydroxyethyl sulfonate, a styrene sulfonate, and a p-styrene sulfonate.

[0031] Optionally, the pre-polymer solution is mixed with the negative electrode material, and after polymerization and drying, a negative electrode composite material is obtained, wherein the polymerization temperature is 65-80℃, and the polymerization time is 12-20h.

[0032] Optionally, the pre-polymer solution is mixed with the negative electrode material, and after polymerization and drying, a negative electrode composite material is obtained, wherein the drying includes at least one of spray drying and vacuum drying, the inlet temperature of the spray drying is 110-180℃, the outlet temperature of the spray drying is 80-90℃, the temperature of the vacuum drying is 120-150℃, and the vacuum drying time is 20-24h.

[0033] Optionally, the polymer solution is mixed with the negative electrode material, and after drying, the negative electrode composite material is obtained, wherein the drying includes at least one of spray drying and vacuum drying, the inlet temperature of the spray drying is 110-180℃, the outlet temperature of the spray drying is 80-90℃, the temperature of the vacuum drying is 120-150℃, and the vacuum drying time is 20-24h.

[0034] In a third aspect, the present application provides a negative electrode, including a negative electrode active material layer, wherein the negative electrode active material layer includes the negative electrode composite material of the first aspect, or the negative electrode composite material prepared by the preparation method of the second aspect.

[0035] In a fourth aspect, the present application provides a battery, including a positive electrode and the negative electrode of the third aspect.

[0036] In a fifth aspect, the present application provides an electrical device, including the battery of the fourth aspect.

[0037] The polymer layer in the negative electrode composite material has good flexibility, good combination performance between the polymer layer and the negative electrode material, can avoid direct contact between the negative electrode material and the electrolyte, effectively slow down and reduce the reaction between the negative electrode material and the electrolyte; the polymer layer can promote ion transport and improve ion conductivity; the polymer layer can participate in the formation of the SEI film and serve as the main skeleton of the SEI film, the SEI film formed by the polymer layer has high flexibility and can effectively avoid the occurrence of rupture, thereby reducing the consumption of lithium ions and improving the performance of the battery. The preparation method of the negative electrode composite material is simple and convenient, which is conducive to the use of the negative electrode composite material. The negative electrode and the battery with the negative electrode composite material have excellent electrochemical performance, which is conducive to the use of the negative electrode and the battery in electrical equipment and improves the product competitiveness of the electrical equipment. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. The specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0039] FIG. 1 is a cross-sectional schematic view of a negative electrode composite material provided by an embodiment of the present application.

[0040] FIG. 2 is a cross-sectional schematic view of a negative electrode provided by an embodiment of the present application. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be described clearly and completely in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] Referring to FIG. 1, a cross-sectional schematic view of a negative electrode composite material 100 provided by an embodiment of the present application is shown, wherein the negative electrode composite material 100 comprises a negative electrode material 10 and a polymer layer 20 wrapping the negative electrode material 10, and the material of the polymer layer 20 has carboxyl groups, amide groups and sulfonic acid groups. The polymer layer 20 has good flexibility, the carboxyl groups and amide groups can form bonds with the negative electrode material 10, thereby improving the bonding performance between the polymer layer 20 and the negative electrode material 10, and the polymer layer 20 can long-term, stably and relatively uniformly coat the negative electrode material 10, which can avoid direct contact between the negative electrode material 10 and the electrolyte, effectively slow down and reduce the reaction between the negative electrode material 10 and the electrolyte; the polymer layer 20 having carboxyl groups, amide groups and sulfonic acid groups can promote ion transport and improve ionic conductivity; the polymer layer 20 having carboxyl groups, amide groups and sulfonic acid groups can participate in the formation of SEI film and serve as the main skeleton of SEI film, the SEI film formed by the polymer layer 20 has high flexibility and structural stability, and can effectively avoid rupture, thereby reducing the consumption of lithium ions, so that the negative electrode composite material 100 has excellent coulombic efficiency, capacity, rate performance and cycle stability, which is helpful to improve the electrochemical performance of the battery. Compared with the mode of coating a carbon layer or an inorganic oxide layer on the surface of the negative electrode material 10, the negative electrode material 10 is coated by the polymer layer 20 in the present application, which has better flexibility and coating performance, is not easy to break and fall off, and is more conducive to improving the performance of the negative electrode composite material 100 and facilitating its use in the battery.

[0043] The negative electrode material 10 in the present application can be selected from substances capable of serving as battery negative electrode active materials. In an embodiment of the present application, the negative electrode material 10 comprises at least one of graphite and silicon-based materials. The graphite has high specific energy, good chemical stability and long cycle life, and the silicon-based material has high energy density and high specific capacity, which are all conducive to improving the performance of the negative electrode composite material 100. In an embodiment of the present application, the graphite comprises at least one of natural graphite and artificial graphite. Specifically, the graphite can be purchased or obtained by recycling waste batteries. In some embodiments, the graphite can be graphite having a carbon coating layer, i.e., the surface of the natural graphite or artificial graphite has a carbon coating layer, which further improves the conductivity of the negative electrode composite material 100. In an embodiment of the present application, the silicon-based material comprises at least one of elemental silicon, silicon-oxygen material, silicon-carbon material and silicon alloy material. The silicon alloy material can comprise at least one of silicon-copper alloy, silicon-aluminum alloy, silicon-iron alloy and silicon-lithium alloy.

[0044] The negative electrode material 10 can be a primary particle, a secondary particle, or a mixture of primary particles and secondary particles. In an embodiment, the particle size D50 of the negative electrode material 10 is 8-16 μm. Specifically, the particle size D50 of the negative electrode material 10 can be, but is not limited to, 8 μm, 8.5 μm, 9 μm, 10 μm, 10.5 μm, 11 μm, 12 μm, 13 μm, 13.5 μm, 14 μm, 15.5 μm, 15.5 μm, or 16 μm. The particle size D50 in the present application is the particle size corresponding to the cumulative particle size distribution volume percentage of 50%. Physically, the volume of particles with a particle size greater than the particle size D50 accounts for 50%, and the volume of particles with a particle size less than the particle size D50 also accounts for 50%. D50 is also called the median diameter or the median particle size.

[0045] The polymer layer 20 in the present application coats the negative electrode material 10 and participates in the formation of the SEI film when the negative electrode composite material 100 is used in a battery, effectively improving the structural stability of the SEI film, which is beneficial to improving the electrochemical performance of the battery. The synergistic effect of the carboxyl group, the amide group, and the sulfonic acid group further improves the binding performance and coating performance of the polymer layer 20 to the negative electrode material 10 and the stability of the formed SEI film. The material of the polymer layer 20 in the present application is a three-dimensional network structure, which can better and uniformly coat the negative electrode material 10, effectively avoid the contact between the negative electrode material 10 and the electrolyte, improve the performance of the negative electrode material 10, and further improve the performance of the battery. In an embodiment, the coating rate of the polymer layer 20 to the negative electrode material 10 is greater than 90%. The coating rate is the ratio of the orthogonal projection area of the polymer layer 20 on the surface of the negative electrode material 10 to the surface area of the negative electrode material 10. Specifically, the coating rate of the polymer layer 20 to the negative electrode material 10 is greater than 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 100%. In an example, the coating rate of the polymer layer 20 to the negative electrode material 10 is 100%, i.e., the polymer layer 20 completely coats the negative electrode material 10, which can effectively avoid the direct contact between the electrolyte and the negative electrode material 10, and further improve the performance of the negative electrode material 10.

[0046] The material of the polymer layer 20 in the present application is a copolymer. In an embodiment of the present application, the polymer monomers of the copolymer include a first monomer, a second monomer and a third monomer, the first monomer includes a carboxyl group, the second monomer includes an amide group, and the third monomer includes a sulfonic acid group. That is, the first monomer, the second monomer and the third monomer are copolymerized to form the polymer layer 20 with the carboxyl group, the amide group and the sulfonic acid group. In an embodiment of the present application, the first monomer can include acrylic acid, thereby providing the carboxyl group. In an embodiment of the present application, the second monomer can further include at least one of an alkenyl group, a carboxyl group and a hydroxyl group, thereby facilitating the polymerization between the first monomer, the second monomer and the third monomer. For example, the second monomer can include an alkenyl amide. Specifically, the second monomer can include, but is not limited to, at least one of acrylamide, N-vinyl caprolactam, N-tert-butyl acrylamide, N-octyl acrylamide and N,N-methylene bisacrylamide. In an embodiment of the present application, the third monomer further includes at least one of an alkenyl group, a carboxyl group and a hydroxyl group, thereby facilitating the polymerization between the first monomer, the second monomer and the third monomer. For example, the third monomer can include an alkenyl sulfonate. Specifically, the third monomer can include, but is not limited to, at least one of an alpha-alkenyl sulfonate, an allyl sulfonate, a methacryl sulfonate, a hydroxyethyl sulfonate, a styrene sulfonate and a p-styrene sulfonate. The third monomer can be a sulfonic acid group salt, such as at least one of a sodium sulfonate and a potassium sulfonate. In an embodiment of the present application, the copolymer includes an acrylic acid-alkenyl amide-alkenyl sulfonate copolymer. The carboxyl group in the copolymer can be chemically combined with the oxygen-containing groups on the surface of the negative electrode material 10, the amide group can also be combined with the negative electrode material 10 by hydrogen bonding, thereby improving the binding performance and coating performance between the polymer layer 20 and the negative electrode material 10; at the same time, the carboxyl group, the amide group and the sulfonic acid group can all participate in the formation of the SEI film, and are conducive to the conduction of lithium ions, thereby improving the performance of the negative electrode composite material 100 and the battery.

[0047] In the present application, the Fourier infrared spectrum of the polymer layer 20 of the negative electrode composite material 100 can be tested by using a Thermo Nicolet iS50 FTIR spectrometer; for example, the infrared spectrum of the polymer layer 20 of the negative electrode composite material 100 can include a C=O peak at 1650 cm -1 ~1750 cm -1 a C-O peak at 1320 cm -1 ~1210 cm -1 a N-H peak at 3500 cm -1 ~3100 cm -1 a C-N peak at 1420 cm -1 ~1400 cm -1 a C-N peak at 700 cm -1 ~900 cm -1The S-O isosbestic peak of the peak position jointly represents that the material of the polymer layer 20 has a carboxyl group, an amide group and a sulfonic acid group. In the present application, the polymer layer 20 of the negative electrode composite material 100 can also be detected by using a Thermo K-Alpha X-ray photoelectron spectrometer (XPS); for example, the C-N bond appearing at 285eV-286eV in the C1s signal spectrum, the C=O bond appearing at 288eV-289eV, the C-N bond appearing at ~400eV in the N1s signal spectrum, and the S=O at ~533eV in the O1s signal spectrum jointly represent that the material of the polymer layer 20 has a carboxyl group, an amide group and a sulfonic acid group.

[0048] In an embodiment of the present application, the negative electrode material 10 and the polymer layer 20 are combined by hydrogen bonds. The carboxyl group and the amide group of the polymer layer 20 can form hydrogen bonds with the oxygen-containing groups of the negative electrode material 10, thereby improving the combination effect of the negative electrode material 10 and the polymer layer 20. In an embodiment of the present application, the negative electrode material 10 and the polymer layer 20 can also form an ester bond, thereby further improving the combination effect of the negative electrode material 10 and the polymer layer 20. The carboxyl group of the polymer layer 20 can be dehydrated and condensed with the hydroxyl group on the surface of the negative electrode material 10 to form an ester bond.

[0049] In the present application, the Fourier infrared spectrum of the negative electrode composite material 100 can be tested by using a Thermo Nicolet iS50 FTIR spectrometer, and in the infrared spectrum, the strong and wide absorption peak appearing at 3300cm -1 ~3500cm -1 The strong and wide absorption peak appearing at the peak position represents intermolecular hydrogen bonds, the C=O bond appearing at ~1750cm -1 The C=O bond appearing at the peak position and the C-O bond appearing at 1210cm -1 ~1160cm -1 The C-O bond appearing at the peak position jointly represents an ester bond. Specifically, a discharged battery can be disassembled to obtain a negative electrode sheet, the coating in any coating area is scraped, and the scraped material is placed in a centrifuge tube containing an ethanol solution, then ultrasonic cleaning is performed in an ultrasonic cleaning machine for 20min, and the negative electrode composite material 100 is obtained after filtration and drying, and the hydrogen bonds and the ester bonds are detected.

[0050] In an embodiment of the present application, the thickness of the polymer layer 20 is 1 nm-80 nm, which can play a coating role for the negative electrode material 10, and meanwhile, will not affect the transmission of lithium ions, and can also serve as the main skeleton of the subsequent SEI film, improve the flexibility of the SEI film, and improve the use performance of the negative electrode composite material 100 and the battery. Specifically, the thickness of the polymer layer 20 can be, but is not limited to, 1 nm, 5 nm, 8 nm, 10 nm, 13 nm, 15 nm, 17 nm, 19 nm, 20 nm, 23 nm, 25 nm, 28 nm, 30 nm, 35 nm, 40 nm, 45 nm, 48 nm, 50 nm, 53 nm, 55 nm, 57 nm, 60 nm, 65 nm, 70 nm, 75 nm, or 80 nm, etc. In an embodiment of the present application, the thickness of the polymer layer 20 can be 5 nm-60 nm, which can play a better coating effect for the negative electrode material 10, and meanwhile, will not reduce the content of the negative electrode material 10 in the negative electrode composite material 100, and further improve the use performance of the negative electrode composite material 100.

[0051] In an embodiment of the present application, the mass ratio of the polymer layer 20 to the negative electrode material 10 in the negative electrode composite material 100 is 0.4%-8%, which can ensure the coating effect of the polymer layer 20 for the negative electrode material 10, and also ensure the flexibility of the subsequent SEI film, and further ensure the mass content of the negative electrode material 10 in the negative electrode composite material 100, which is beneficial to further improve the use performance of the negative electrode composite material 100. Specifically, the mass ratio of the polymer layer 20 to the negative electrode material 10 in the negative electrode composite material 100 can be, but is not limited to, 0.4%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.7%, 2%, 2.5%, 3%, 3.5%, 3.9%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, or 8%, etc. In an embodiment of the present application, the mass ratio of the polymer layer 20 to the negative electrode material 10 in the negative electrode composite material 100 can be 0.4%-5%, which further improves the use performance of the negative electrode composite material 100.

[0052] In an embodiment of the present application, the particle size D50 of the negative electrode composite material 100 is 8 μm-16.2 μm. Specifically, the particle size D50 of the negative electrode composite material 100 can be, but is not limited to, 8 μm, 8.1 μm, 8.5 μm, 9 μm, 10 μm, 10.5 μm, 11 μm, 12 μm, 13 μm, 13.5 μm, 14 μm, 15.5 μm, 15.5 μm, 16 μm or 16.2 μm, etc. When the particle size D50 of the negative electrode composite material 100 is determined, the test method specifically includes the following steps: a) disassembling the battery with complete discharge to obtain the negative electrode sheet, and then cutting the coating area at any position by argon ion to obtain the negative electrode sheet cross-section sample; b) placing the above-mentioned negative electrode sheet cross-section sample in the SEM for observation, adjusting the electron microscope voltage, the magnification is about 10k, ensuring that enough particles in the above-mentioned sample can be clearly seen and photographed to obtain the SEM photo; c) importing the obtained SEM photo into the gray scale debugging software (Geodict) to statistically analyze the particle size; d) accumulating 20 experiments, the number of particles in each experiment is not less than 500 pcs, and after statistically analyzing the above-mentioned results, the median particle size D50 of the negative electrode composite material 100 in the negative electrode sheet is obtained.

[0053] In an embodiment of the present application, the specific surface area of the negative electrode composite material 100 is 2 m 2 / g-4 m 2 / g. The specific surface area of the negative electrode composite material 100 is small, which can effectively reduce the infiltration of the electrolyte and improve the performance of the negative electrode composite material 100. Specifically, the specific surface area of the negative electrode composite material 100 can be, but is not limited to, 2 m 2 / g, 2.2 m 2 / g, 2.4 m 2 / g, 2.5 m 2 / g, 2.7 m 2 / g, 2 m 2 / g, 3.3 m 2 / g, 3.5 m 2 / g, 3.8 m 2 / g or 4 m 2 / g, etc. In an embodiment of the present application, the specific surface area of the negative electrode composite material 100 can be 2.2 m 2 / g-3.8 m 2 / g, further improving the performance of the negative electrode composite material 100.

[0054] In an embodiment of the present application, the first de-lithiation capacity of the negative electrode composite material 100 is greater than or equal to 350 mAh / g. Specifically, the first de-lithiation capacity of the negative electrode composite material 100 is greater than or equal to 351 mAh / g, greater than or equal to 352 mAh / g, greater than or equal to 353 mAh / g, greater than or equal to 354 mAh / g, greater than or equal to 355 mAh / g, greater than or equal to 357 mAh / g, or greater than or equal to 360 mAh / g, etc. In an embodiment of the present application, the first coulombic efficiency of the negative electrode composite material 100 is greater than or equal to 89%. Specifically, the first coulombic efficiency of the negative electrode composite material 100 is greater than or equal to 90%, greater than or equal to 91%, greater than or equal to 92%, or greater than or equal to 93%, etc. In the above, the negative electrode composite material 100 is mixed with carbon black, sodium carboxymethyl cellulose, and butadiene-styrene rubber in a mass ratio of 96:1.5:1:1.5, and then added to water to be stirred uniformly to form a slurry. The slurry is uniformly coated on a copper foil using a coating machine. The electrode piece is placed in a vacuum drying oven at a temperature of 120°C and vacuum dried for 12 hours. The electrode piece is rolled to form an electrode piece. Then, a CR-2025 button lithium ion battery is assembled in an argon-filled glove box. Lithium is used as the counter electrode. The separator is made of polypropylene. The electrolyte solute is 1M LiPF6. The electrolyte solvent is a mixed solution of ethylene carbonate (EC), methyl ethyl carbonate (EMC), and dimethyl carbonate (DMC) (volume ratio of 1:1:1). The first circle 0.05C constant current discharge (lithium intercalation) is performed to 0.01V, and then constant voltage discharge is performed. The cutoff current is 0.02C. Then, the first charge-discharge capacity and the first coulombic efficiency are tested by charging (de-lithiation) to 2.0V using 0.05C constant current. The first de-lithiation capacity and the first coulombic efficiency are obtained.

[0055] The present application provides a preparation method of the negative electrode composite material 100, which comprises: mixing a prepolymer solution with the negative electrode material 10, and obtaining the negative electrode composite material 100 after polymerization and drying, or mixing a polymer solution with the negative electrode material 10, and obtaining the negative electrode composite material 100 after drying. That is, the prepolymer solution can be mixed with the negative electrode material 10, and the negative electrode composite material 100 can be obtained after polymerization and drying. Alternatively, the polymer solution can be directly mixed with the negative electrode material 10, and the negative electrode composite material 100 can be obtained after drying. The negative electrode composite material 100 in any of the above embodiments can be prepared by the preparation method.

[0056] In an embodiment of the present application, the prepolymer solution comprises a first monomer, a second monomer, a third monomer, and an initiator. The first monomer comprises a carboxyl group. The second monomer comprises an amide group. The third monomer comprises a sulfonic acid group. The specific selection of the first monomer, the second monomer, and the third monomer is as described above, and will not be repeated here. The first monomer, the second monomer, and the third monomer can undergo a free radical polymerization reaction under the action of the initiator to form a copolymer.

[0057] In one embodiment of the present application, the mass ratio of the first monomer, the second monomer, and the third monomer is (1-8): (1-3): (1-4), which is conducive to the copolymerization of the first monomer, the second monomer, and the third monomer to form the polymer layer 20. Specifically, the mass ratio of the first monomer, the second monomer, and the third monomer can be, but is not limited to, (3-8): (2-3): (2-4), (4-8): (2-3): (3-4), (5-8): (1-3): (1-4), or (6-8): (1-3): (1-4). In one embodiment, the mass ratio of the first monomer, the second monomer, and the third monomer can be (5-8): (1-3): (1-4). A high content of carboxyl groups is conducive to the full progress of the polymerization reaction. At the same time, the content of amide groups and sulfonic acid groups also ensures that the subsequently formed polymer layer 20 participates in the formation of the SEI film. For example, the mass ratio of the first monomer, the second monomer and the third monomer can be 1:1:1, 2:3:4, 5:3:1, 7:3:4 or 8:3:4, etc., wherein the first monomer can be acrylic acid, the second monomer can be alkenyl amide, and the third monomer can be sodium alkenyl sulfonate.

[0058] In one embodiment of the present application, the ratio of the sum of the mass of the first monomer, the second monomer, and the third monomer to the mass of the prepolymer solution is 5%-15%. This ensures the mass content of the first monomer, the second monomer, and the third monomer, which is conducive to polymer formation, and also ensures the polymerization reaction. Specifically, the ratio of the sum of the mass of the first monomer, the second monomer, and the third monomer to the mass of the prepolymer solution can be, but is not limited to, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%.

[0059] In one embodiment of the present application, the ratio of the mass of the initiator to the mass sum of the first monomer, the second monomer and the third monomer is 0.4%-2%, which ensures the progress of the polymerization reaction and is conducive to the formation of the copolymer. Specifically, the ratio of the mass of the initiator to the mass sum of the first monomer, the second monomer and the third monomer can be, but is not limited to, 0.4%, 0.5%, 0.7%, 0.8%, 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 1.9% or 2%, etc. In one embodiment of the present application, the initiator includes at least one of persulfate and azobisisobutylimidazoline hydrochloride. Among them, the persulfate can include, but is not limited to, at least one of ammonium persulfate, potassium persulfate and sodium persulfate.

[0060] In the present application, the solvent of the prepolymerization solution is used to dissolve and disperse the first monomer, the second monomer, the third monomer, the initiator, and the negative electrode material 10, and the solvent of the prepolymerization solution does not react with the above substances. Specifically, the solvent of the prepolymerization solution includes at least one of methanol, ethanol, ether, isopropanol, and dimethyl sulfoxide.

[0061] In the present application, the negative electrode material 10 such as graphite, silicon-based material, etc. can be treated (such as low-temperature pre-oxidation) to make the surface of the negative electrode material 10 have oxygen-containing groups such as hydroxyl groups, which is beneficial to the combination between the negative electrode material 10 and the polymer layer 20. In an embodiment of the present application, the mass ratio of the mass sum of the first monomer, the second monomer and the third monomer to the mass of the negative electrode material 10 is 0.4%-8%, which not only ensures the coating effect of the polymer layer 20 on the negative electrode material 10, but also ensures the flexibility of the SEI film formed subsequently, and also ensures the mass content of the negative electrode material 10 in the negative electrode composite material 100, which is beneficial to further improving the use performance of the negative electrode composite material 100. Specifically, the mass ratio of the mass sum of the first monomer, the second monomer and the third monomer to the mass of the negative electrode material 10 can be but is not limited to 0.4%, 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.7%, 2%, 2.5%, 3%, 3.5%, 3.9%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5% or 8%, etc. In an embodiment of the present application, the mass ratio of the mass sum of the first monomer, the second monomer and the third monomer to the mass of the negative electrode material 10 can be 1%-6%, which further improves the use performance of the negative electrode composite material 100. In an embodiment of the present application, the specific surface area of the negative electrode material 10 is 2.5m 2 / g-9m 2 / g. Specifically, the specific surface area of the negative electrode composite material 100 can be but is not limited to 2.5m 2 / g, 3m 2 / g, 4m 2 / g, 5m 2 / g, 6m 2 / g, 7m 2 / g, 8m 2 / g or 9m 2 / g, etc.

[0062] In an embodiment of the present application, the polymerization temperature is 65°C-80°C, and the polymerization time is 12h-20h, which is beneficial to sufficient polymerization and helps the formation of the polymer layer 20. Specifically, the polymerization temperature can be but is not limited to 65°C, 67°C, 68°C, 70°C, 72°C, 75°C, 76°C, 78°C or 80°C, etc., and the polymerization time can be but is not limited to 12h, 13h, 14h, 15h, 16h, 17h, 18h, 19h or 20h, etc. In an embodiment of the present application, the polymerization can be carried out under an inert atmosphere (such as argon, etc.), which improves the quality of the copolymer formed. In an embodiment of the present application, the mixing and polymerization can be carried out at a stirring speed of 400r / min-800r / min, which accelerates uniform mixing and accelerates polymerization.

[0063] In the present application, the solvent is removed by drying to form the polymer layer 20 coated on the negative electrode material 10, and at the same time, a dehydration reaction can occur during the drying process, so that an ester bond is formed between the polymer layer 20 and the oxygen-containing group of the negative electrode material 10, further improving the binding force between the two. In an embodiment of the present application, the drying includes at least one of spray drying and vacuum drying. In an embodiment of the present application, the inlet temperature of the spray drying is 110-180°C, and the outlet temperature of the spray drying is 80-90°C. In an embodiment of the present application, the temperature of the vacuum drying is 120-150°C, and the time of the vacuum drying is 20-24h.

[0064] In the present application, the method of mixing the prepolymer solution and the negative electrode material 10 and then polymerizing, the multiple monomers in situ polymerize during the blending with the negative electrode material 10, and the polymer mixed solution, which is obtained by the polymerization of the prepolymer solution, is directly mixed with the negative electrode material 10, thereby reducing the in situ polymerization process. The whole process is in liquid phase and at a relatively low preparation temperature, which can reduce the preparation cost, is easy to mass-produce, and the thickness and structure of the polymer layer 20 are highly adjustable and have good flexibility. The polymer layer 20 formed by polymerization can be closely combined on the surface of the negative electrode material 10, the polymer distribution has good continuity, and the negative electrode material 10 can be uniformly coated.

[0065] The present application provides a negative electrode including a negative electrode active material layer, wherein the negative electrode active material layer includes the negative electrode composite material 100 in any of the above embodiments or the negative electrode composite material 100 prepared by any of the above embodiments. The negative electrode with the negative electrode composite material 100 has high initial efficiency, excellent rate performance and cycle performance, which is beneficial to its use in batteries.

[0066] In an embodiment of the present application, the mass content of the negative electrode composite material 100 in the negative electrode active material layer is greater than or equal to 80%, which is beneficial to improving the electrochemical performance of the negative electrode. Specifically, the mass content of the negative electrode composite material 100 in the negative electrode active material layer is greater than or equal to 82%, 85%, 88%, 90%, 93%, 95%, 97% or 98%, etc.

[0067] In an embodiment of the present application, the negative active material layer can further include at least one of a negative conductive agent and a negative binder. Specifically, the negative conductive agent can include, but is not limited to, at least one of conductive carbon black, carbon nanotube, carbon fiber, carbon black, and graphite; and the negative binder can include, but is not limited to, at least one of polytetrafluoroethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, butyl-styrene latex, and butyl nitrile rubber. In an embodiment of the present application, the mass content of the negative conductive agent in the negative active material layer is less than or equal to 5%. Specifically, the mass content of the negative conductive agent in the negative active material layer can be, but is not limited to, 0.1%, 0.5%, 1%, 2%, 3%, 4%, or 5%, etc. In an embodiment, the mass content of the negative conductive agent in the negative active material layer can be 0.1%-5%. In an embodiment of the present application, the mass content of the negative binder in the negative active material layer is less than or equal to 10%. Specifically, the mass content of the negative binder in the negative active material layer can be, but is not limited to, 0.1%, 0.5%, 2%, 4%, 5%, 7%, 8%, or 9%, etc. In an embodiment, the mass content of the negative binder in the negative active material layer is 0.1%-10%.

[0068] In an embodiment of the present application, the thickness of the negative active material layer is 10 μm-100 μm, which can ensure the electrochemical performance of the negative electrode while not excessively increasing the weight of the negative electrode. Specifically, the thickness of the negative active material layer can be, but is not limited to, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, or 100 μm, etc.

[0069] In an embodiment of the present application, the negative electrode further includes a negative current collector, and the negative active material layer is disposed on the surface of the negative current collector. Please refer to FIG. 2, which is a schematic cross-sectional view of a negative electrode provided in an embodiment of the present application, wherein the negative electrode 200 includes a negative current collector 210 and a negative active material layer 220 disposed on the surface of the negative current collector 210, and the negative active material layer 220 includes the negative composite material 100. In an embodiment of the present application, the negative current collector is selected from a metal foil or an alloy foil. Specifically, the metal foil includes copper, aluminum, nickel, iron, or cobalt foil, and the alloy foil includes an alloy of at least one of copper, aluminum, nickel, iron, and cobalt or stainless steel. In an embodiment, the material of the negative current collector includes at least one of copper, aluminum, nickel, iron, and cobalt or stainless steel. Specifically, the negative current collector can be a copper foil. In an embodiment of the present application, at least one of a binder and a conductive agent can be mixed with the negative composite material 100 in an organic solvent to form a mixed slurry, the mixed slurry is coated on the surface of the negative current collector, and the negative electrode is obtained after drying.

[0070] The application provides a battery, which comprises a positive electrode and the negative electrode in any of the above embodiments. The battery with the negative electrode has excellent initial efficiency, rate performance and cycle performance, which is beneficial to the use of the battery. Specifically, the battery can be but is not limited to a lithium ion battery.

[0071] In an embodiment of the application, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer disposed on the surface of the positive electrode current collector. In an embodiment of the application, the positive electrode current collector is selected from a metal foil or an alloy foil. Specifically, the metal foil comprises a copper foil, a titanium foil, an aluminum foil, a platinum foil, an iridium foil, a ruthenium foil, a nickel foil, a tungsten foil, a tantalum foil, a gold foil or a silver foil, and the alloy foil comprises stainless steel or an alloy containing at least one of copper, titanium, aluminum, platinum, iridium, ruthenium, nickel, tungsten, tantalum, gold and silver. Specifically, the positive electrode current collector can be an aluminum foil.

[0072] In an embodiment of the application, the positive electrode active material layer comprises at least one of a positive electrode binder and a positive electrode conductive agent, and a positive electrode active material. Specifically, the positive electrode active material comprises at least one of a layered structure oxide (such as lithium cobaltate, lithium nickel cobalt manganese ternary, lithium nickel cobalt aluminate ternary, transition metal layered oxide, etc.), a polyanion material (such as lithium iron phosphate, lithium iron manganese phosphate, lithium iron sodium phosphate, sodium vanadium phosphate, etc.), a spinel oxide (such as lithium manganese oxide, lithium nickel manganese oxide, etc.); the positive electrode conductive agent can comprise but is not limited to at least one of conductive carbon black, carbon nanotube, carbon fiber, carbon black and graphite; the positive electrode binder can comprise but is not limited to at least one of polytetrafluoroethylene, polyvinylidene fluoride, sodium carboxymethyl cellulose, butyl rubber latex and butyl rubber. In an embodiment, the mass content of the positive electrode active material in the positive electrode active material layer is greater than or equal to 80%, which is beneficial to improving the electrochemical performance of the positive electrode. Specifically, the mass content of the positive electrode active material in the positive electrode active material layer can be greater than or equal to 82%, 85%, 88%, 90%, 93%, 95%, 97% or 98%, etc. In an embodiment, the mass content of the positive electrode conductive agent in the positive electrode active material layer is less than or equal to 5%. Specifically, the mass content of the positive electrode conductive agent in the positive electrode active material layer can be but is not limited to 0.1%, 0.5%, 1%, 2%, 3%, 4% or 5%, etc. In an embodiment, the mass content of the positive electrode conductive agent in the positive electrode active material layer can be 0.1%-5%. In an embodiment, the mass content of the positive electrode binder in the positive electrode active material layer is less than or equal to 10%. Specifically, the mass content of the positive electrode binder in the positive electrode active material layer can be but is not limited to 0.1%, 0.5%, 2%, 4%, 5%, 7%, 8% or 9%, etc. In an embodiment, the mass content of the positive electrode binder in the positive electrode active material layer is 0.1%-10%.

[0073] In an embodiment of the present application, the battery further comprises an electrolyte. In an embodiment of the present application, at least part of the positive electrode is immersed in the electrolyte, and at least part of the negative electrode is immersed in the electrolyte, so as to ensure normal operation of the battery. In an embodiment of the present application, the electrolyte comprises a solute and an organic solvent. The solute can be selected according to the type of the battery, for example, the solute of the electrolyte in a lithium ion battery can be lithium salt. Specifically, the lithium salt can include, but is not limited to, at least one of lithium hexafluorophosphate, lithium hexafluoroarsenate, lithium perchlorate, lithium hexafluoroborate and lithium bis-trifluoromethanesulfonimide; and the organic solvent can include, but is not limited to, at least one of ethylene carbonate (EC), methyl ethyl carbonate (EMC), dimethyl carbonate (DMC), diethyl carbonate (DEC), vinylene carbonate (VC) and fluoroethylene carbonate (FEC).

[0074] The present application provides a power consuming device comprising the battery of any of the above embodiments. The battery in the power consuming device provided by the present application has excellent electrochemical performance, thereby improving the use performance and service life of the power consuming device. Specifically, the power consuming device can refer to a vehicle, an electronic device, an energy storage system, etc., and the above battery can be arranged in the power consuming device in the form of a single battery, a battery module, a battery pack, etc.

[0075] The effects of the technical solutions of the present application are further described below through specific examples.

[0076] Embodiment 1

[0077] The acrylic monomer, the alkenyl amide monomer (acrylamide) and the alkenyl sulfonate sodium monomer (allyl sulfonate sodium) are added into a solvent (50% by volume concentration of an aqueous ethanol solution) at a mass ratio of 8:3:4, and then a initiator sodium persulfate (the mass ratio of the initiator to the sum of the masses of the above three monomers is 0.5%) is added and uniformly mixed at room temperature. Subsequently, spherical natural graphite (specific surface area 8.74 m 2 / g) is added, and the mass ratio of the sum of the masses of the above three monomers to the mass of the spherical natural graphite is 3%. The mixture is stirred (at a speed of 700 r / min) under an argon atmosphere and in-situ polymerized at 65°C for 12 h to obtain a mixed solution. The mixed solution is spray dried (the inlet temperature is 150°C and the outlet temperature is 90°C), and then cooled to obtain a negative electrode composite material 100. The negative electrode composite material 100 comprises graphite and a polymer layer 20 wrapping the graphite, and the material of the polymer layer 20 is an acrylic acid-alkenyl amide-alkenyl sulfonate copolymer.

[0078] Embodiment 2

[0079] The embodiment is substantially the same as Embodiment 1, except that the mass ratio of the sum of the masses of the three monomers to the mass of the spherical natural graphite is 5%.

[0080] Embodiment 3

[0081] The same as Example 1 except that the ratio of the mass of the three monomers to the mass of the spherical natural graphite was 0.4%.

[0082] Example 4

[0083] The same as Example 1 except that the ratio of the mass of the three monomers to the mass of the spherical natural graphite was 8%.

[0084] Example 5

[0085] The same as Example 1 except that the ratio of the mass of the initiator to the sum of the masses of the three monomers was 2%.

[0086] Example 6

[0087] The same as Example 1 except that the temperature of the polymerization was 75°C.

[0088] Example 7

[0089] The same as Example 1 except that the time of the polymerization was 20 h.

[0090] Example 8

[0091] The same as Example 1 except that the acrylic monomer, the alkenyl amide monomer, and the sodium alkenyl sulfonate monomer were added to the solvent in a mass ratio of 4:1:1.

[0092] Example 9

[0093] The same as Example 1 except that the acrylic monomer, the alkenyl amide monomer, and the sodium alkenyl sulfonate monomer were added to the solvent in a mass ratio of 1:2:1.

[0094] Example 10

[0095] The same as Example 1 except that the temperature of the polymerization was 80°C.

[0096] Example 11

[0097] The same as Example 1 except that the argon atmosphere was changed to an air atmosphere.

[0098] Example 12

[0099] The same as Example 1 except that the spray drying was changed to vacuum drying (temperature of 150°C, time of 12 h).

[0100] Example 13

[0101] The same as Example 1 except that the spherical natural graphite was changed to carbon-coated natural graphite (specific surface area of 3.5 m 2 / g).

[0102] Example 14

[0103] The same as Example 1, except that the mass ratio of acrylic monomer, alkenyl amide monomer, and sodium alkenyl sulfonate monomer is 8:1:1, and the mass ratio of the three monomers to the mass of the spherical natural graphite is 8%.

[0104] Comparative Example 1

[0105] The spherical natural graphite in Example 1 was directly used.

[0106] Comparative Example 2

[0107] The same as Example 5, except that the acrylic monomer and the alkenyl amide monomer were added to the solvent in a mass ratio of 4:1, and the sodium alkenyl sulfonate monomer was not included.

[0108] Comparative Example 3

[0109] The same as Example 5, except that the acrylic monomer and the sodium alkenyl sulfonate monomer were added to the solvent in a mass ratio of 4:1, and the alkenyl amide monomer was not included.

[0110] Comparative Example 4

[0111] The same as Example 5, except that the alkenyl amide monomer and the sodium alkenyl sulfonate monomer were added to the solvent in a mass ratio of 3:4, and the acrylic monomer was not included.

[0112] Comparative Example 5

[0113] The same as Example 5, except that the acrylic monomer was added to the solvent, and the alkenyl amide monomer and the sodium alkenyl sulfonate monomer were not included.

[0114] Comparative Example 6

[0115] The same as Example 5, except that the alkenyl amide monomer was added to the solvent, and the acrylic monomer and the sodium alkenyl sulfonate monomer were not included.

[0116] Comparative Example 7

[0117] The same as Example 5, except that the sodium alkenyl sulfonate monomer was added to the solvent, and the acrylic monomer and the alkenyl amide monomer were not included.

[0118] Performance Test

[0119] The BET specific surface area of the products prepared in the above examples and comparative examples was detected by a specific surface tester; the thickness of the polymer layer 20 in the negative electrode composite material 100 prepared in the above examples was detected by a transmission electron microscope, and the results are shown in Table 1.

[0120] The product prepared in the above examples and comparative examples was mixed with carbon black, sodium carboxymethyl cellulose, butyl rubber in a mass ratio of 96:1.5:1:1.5, and then added to water to be stirred uniformly to prepare a negative electrode slurry. The negative electrode slurry was uniformly coated on a copper foil using a coating machine, the electrode piece was placed in a vacuum drying oven at a temperature of 120°C and vacuum dried for 12h, and then rolled to prepare a negative electrode piece. Then, a CR-2025 type button lithium ion battery was assembled in an argon-filled glove box, a lithium piece was used as a counter electrode, a separator was made of polypropylene, an electrolyte solute was 1M LiPF6, and an electrolyte solvent was a mixed solution of ethylene carbonate (EC), methyl ethyl carbonate (EMC) and dimethyl carbonate (DMC) (volume ratio of 1:1:1).

[0121] The first cycle coulombic efficiency, rate performance and cycle performance of the battery prepared above were detected, and the results are shown in Table 1; wherein, the first cycle coulombic efficiency test: 0.05C constant current discharge to 0.01V, then constant voltage discharge, the cutoff current is 0.02C, then charge to 2.0V with 0.05C constant current; the rate performance test: discharge to 0.01V with 0.05C constant current, then constant voltage discharge, the cutoff current is 0.02C, then charge to 2.0V with 0.05C constant current, after repeating the above steps three times, discharge to 0.01V with 0.2C, then constant voltage discharge, the cutoff current is 0.05C, then charge to 2.0V with 5C constant current; the cycle performance test: discharge to 0.01V with 0.05C constant current, then constant voltage discharge, the cutoff current is 0.02C, then charge to 2.0V with 0.05C constant current, after repeating the above steps three times, charge and discharge at a rate of 0.5C, and the charge and discharge interval is 0.01V-2.0V.

[0122] Table 1 Performance Test Results

[0123] The specific surface area and the thickness of the polymer layer 20 of the negative electrode composite material 100 prepared by the embodiments of the present application are suitable, and the material of the polymer layer 20 is an acrylic-alkyl amide-alkyl sulfonate copolymer, which has carboxyl, amide and sulfonic acid groups. The comparative example 1 directly uses spherical natural graphite as the negative electrode material 10, which does not contain the polymer layer 20. The negative electrode composite materials 100 provided by the comparative examples 2 to 7 have the polymer layer 20 coated on the spherical natural graphite, but the polymer layer 20 does not contain one or two of the carboxyl, amide and sulfonic acid groups. As can be seen from Table 1, the first circle coulomb efficiency, the first circle lithium extraction specific capacity, the lithium extraction specific capacity under 5C and the capacity retention rate after 200 cycles of the battery prepared by the negative electrode composite material 100 provided by the embodiments of the present application are all better than the performance of the batteries prepared by the comparative examples 1 to 7, especially the comparative example 1. Therefore, the negative electrode composite material 100 provided by the present application containing the polymer layer 20 with carboxyl, amide and sulfonic acid groups can effectively improve the first circle coulomb efficiency, the rate performance and the cycle performance of the battery, which is beneficial to the use of the battery.

[0124] The above describes the preferred embodiments of the present application, but cannot be understood as limiting the scope of the present application. It should be noted that for those skilled in the art, some improvements and refinements can be made without departing from the principles of the present application, and these improvements and refinements are also considered within the protection scope of the present application.

Claims

1. A negative electrode composite material (100), characterized in that: The invention comprises a negative electrode material (10) and a polymer layer (20) wrapping the negative electrode material (10), wherein the material of the polymer layer (20) has a carboxyl group, an amide group and a sulfonic acid group.

2. The negative electrode composite material (100) according to claim 1, characterized in that The polymer monomers of the material of the polymer layer (20) include a first monomer, a second monomer and a third monomer, the first monomer includes the carboxyl group, the second monomer includes the amide group, and the third monomer includes the sulfonic acid group.

3. The negative electrode composite material (100) according to claim 2, characterized in that The first monomer includes acrylic acid; The second monomer further comprises at least one of an alkenyl group, a carboxyl group, and a hydroxyl group; The third monomer further includes at least one of an alkenyl group, a carboxyl group, and a hydroxyl group.

4. The negative electrode composite material (100) according to any one of claims 1 to 3, characterized in that: The material of the polymer layer (20) includes acrylic acid-alkenylamide-alkenylsulfonate copolymer.

5. The negative electrode composite material (100) according to claim 1, characterized in that There is a hydrogen bond between the negative electrode material (10) and the polymer layer (20).

6. The negative electrode composite material (100) according to claim 5, characterized in that There is also an ester bond between the negative electrode material (10) and the polymer layer (20).

7. The negative electrode composite material (100) according to claim 1, characterized in that The thickness of the polymer layer (20) is 1 nm to 80 nm; The coverage rate of the polymer layer (20) on the negative electrode material (10) is greater than 90%; The particle size D50 of the negative electrode material (10) is 8 μm-16 μm; The particle size D50 of the negative electrode composite material (100) is 8 μm-16.2 μm; The specific surface area of ​​the negative electrode composite material (100) is 2 m 2 / g-4m 2 / g; The negative electrode material (10) includes at least one of graphite and silicon-based materials; The mass ratio of the polymer layer (20) to the negative electrode material (10) in the negative electrode composite material (100) is 0.4%-8%.

8. A method for preparing a negative electrode composite material (100), characterized in that: include: A prepolymer solution is mixed with a negative electrode material (10), and after polymerization and drying, a negative electrode composite material (100) is obtained, or a polymer solution is mixed with the negative electrode material (10), and after drying, the negative electrode composite material (100) is obtained. The negative electrode composite material (100) includes the negative electrode material (10) and a polymer layer (20) wrapping the negative electrode material (10), and the material of the polymer layer (20) has a carboxyl group, an amide group, and a sulfonic acid group.

9. The preparation method according to claim 8, wherein The prepolymerization solution includes a first monomer, a second monomer, a third monomer and an initiator, wherein the first monomer includes the carboxyl group, the second monomer includes the amide group, and the third monomer includes the sulfonic acid group; The mass ratio of the first monomer, the second monomer and the third monomer is (1-8):(1-3):(1-4); The ratio of the sum of the mass of the first monomer, the second monomer and the third monomer to the mass of the prepolymerization solution is 5%-15%; The ratio of the mass of the initiator to the mass of the first monomer, the second monomer and the third monomer is 0.4%-2%; The initiator includes at least one of persulfate and azobisisobutylimidazoline hydrochloride; The first monomer includes acrylic acid; The second monomer comprises at least one of acrylamide, N-vinylcaprolactam, N-tert-butylacrylamide, N-octylacrylamide and N,N-methylenebisacrylamide; The third monomer includes at least one of α-olefin sulfonate, allyl sulfonate, methacrylic sulfonate, isethionate, styrene sulfonate and p-styrene sulfonate.

10. The preparation method according to claim 8, characterized in that The prepolymerization solution is mixed with the negative electrode material (10), and after polymerization and drying, a negative electrode composite material (100) is obtained. The polymerization temperature is 65° C.-80° C., and the polymerization time is 12 hours-20 hours.

11. The preparation method according to claim 8, wherein The prepolymer solution is mixed with the negative electrode material (10), polymerized, and dried to obtain a negative electrode composite material (100), wherein the drying comprises at least one of spray drying and vacuum drying, the inlet temperature of the spray drying is 110° C.-180° C., the outlet temperature of the spray drying is 80° C.-90° C., the temperature of the vacuum drying is 120° C.-150° C., and the time of the vacuum drying is 20 h-24 h; or The polymer solution is mixed with the negative electrode material (10), and dried to obtain the negative electrode composite material (100), wherein the drying includes at least one of spray drying and vacuum drying, the inlet temperature of the spray drying is 110°C-180°C, the outlet temperature of the spray drying is 80°C-90°C, the temperature of the vacuum drying is 120°C-150°C, and the time of the vacuum drying is 20h-24h.

12. A negative electrode, characterized in that: The negative electrode active material layer comprises the negative electrode composite material (100) according to any one of claims 1 to 7, or the negative electrode composite material (100) prepared by the preparation method according to any one of claims 8 to 11.

13. A battery, characterized in that: The invention comprises a positive electrode and the negative electrode according to claim 12.

14. An electrical device, characterized in that: Including the battery according to claim 13.

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