Negative electrode material for lithium battery and application thereof

Abstract

The application belongs to the field of lithium battery manufacturing, and provides a negative electrode material for lithium battery and application thereof, which comprises a graphite negative electrode material, a modified silicon-oxygen negative electrode material, and an active composite material obtained by compounding the two in different proportions. x The mechanical strength of the modified silicon-oxygen negative electrode material (TiO2 / SiO x particles) is significantly improved, the stress caused by volume change of the silicon-based negative electrode material in the charging and discharging process is effectively relieved, the volume expansion of the silicon-based material is effectively inhibited, the structure stability of the negative electrode material in the cycle process is maintained, the interface stability is good, and the cycle stability of the battery is further improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium battery manufacturing, and specifically relates to a negative electrode material for lithium batteries and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] With increasing awareness of energy conservation and environmental protection, new energy sources (solar, hydro, wind, etc.) have received much attention. As a new energy storage device, lithium-ion batteries have become a new generation of green and high-energy industry, widely used in mobile phones, automobiles, aviation, and other fields. Positive and negative electrode materials, as important components of lithium-ion batteries, directly affect the battery's capacity, voltage platform, and energy density, thus attracting great attention from researchers.

[0004] Compared to consumer lithium batteries, power lithium batteries have more stringent requirements for capacity, voltage platform, and energy density. Current mainstream cathode materials include ternary cathodes, lithium iron phosphate cathodes, and lithium manganese iron phosphate cathodes. While improvements in the specific capacity of cathode materials have largely reached a bottleneck, there is still significant room for improvement in the specific capacity of anodes. Currently, conventional anode materials are mainly graphite, but graphite anodes have a relatively low theoretical specific capacity, affecting the battery's energy density. This low specific capacity is usually addressed by doping with silicon-based or tin-based anode materials, which have higher specific capacity. However, doping with silicon-based materials inevitably leads to large anode rebound due to expansion issues, resulting in poor interparticle contact and ultimately, battery performance degradation.

[0005] Therefore, there is an urgent need to develop a negative electrode material and its preparation method that can meet the requirements of high specific capacity, high voltage platform, effective suppression of expansion problems, excellent cycle performance, and production and processing performance. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a negative electrode material for lithium batteries and its applications. This invention utilizes SiO₂... x The modified silicon-oxygen anode material is prepared by first physically coating TiO2 onto the particle surface and then chemically modifying it with amino groups. This dual physical and chemical coating effectively suppresses expansion, maintains excellent cycle performance, and facilitates production and processing, meeting the requirements of high specific capacity and high voltage platform. On the other hand, the modified silicon-oxygen anode material contains amino groups, which can better combine with the carboxyl-containing binder CMC, improving the electrochemical performance of lithium batteries.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a negative electrode material for lithium batteries, comprising:

[0009] SiO x The particles react with a hydroxylating agent to obtain hydroxyl-modified SiO₂. x Particles;

[0010] The hydroxyl-modified SiO₂ was prepared using a titanium source solution. x The particles are physically coated and calcined to obtain TiO2 / SiO2. x Particles;

[0011] For the TiO2 / SiO x The particles were aminated to obtain a modified silicon-oxygen anode material;

[0012] The modified silicon-oxygen anode material is compounded with graphite anode material at a mass ratio of 99:1-50:50 to obtain the final product.

[0013] Preferably, the mass ratio of the graphite anode material to the modified silicon-oxygen anode material is 98:2-80:20, or 95:5-85:15. The graphite anode is a conventional carbon material, while the modified silicon-oxygen anode material contains a carbon-silicon oxide composite material, and the expansion is suppressed by modifying its surface with functional groups.

[0014] Preferably, the hydroxylating agent is a mixture of hydrogen peroxide and sulfuric acid, wherein the mass ratio of hydrogen peroxide to sulfuric acid is 1:1 to 5:1.

[0015] Preferably, the SiO x The mass ratio of the granules to the mixture of hydrogen peroxide and sulfuric acid is 1:10-3:1.

[0016] Preferably, the titanium source is at least one selected from titanium tert-butoxide, tetrabutyl titanate, tetraethyl titanate, tetraisopropyl titanate, titanium sulfate, titanium oxysulfate, and titanium tetrachloride; more preferably, the titanium source is titanium tert-butoxide.

[0017] Preferably, the SiO₂ containing hydroxyl groups x The ratio of particles to titanium tert-butoxide is 1:3 to 5:1. The treated SiO₂... x The particle surface has a large number of hydroxyl groups attached, which are hydroxyl-containing silicon oxide compounds SiO x Particles added to titanium C containing tert-butoxide 16 H 36 In an ethanol solution of O4Ti, it binds to titanium tert-butoxide C through chemical bonds. 16 H 36 O4Ti has a tighter bond, which effectively improves the cycle performance of lithium batteries.

[0018] Preferably, the calcination conditions are calcination at 600℃~800℃ for 3h~5h.

[0019] Preferably, the acidity adjustment time is 1 to 1.5 hours, the pH of the adjusted solution is 2.5 to 4.5, and the concentration of hydrochloric acid is 5% to 15%.

[0020] Preferably, the amination modification method is to modify the TiO2 / SiO2. x The particles react with 3-aminopropyltrimethoxysilane.

[0021] Preferably, TiO2 / SiO x The mass ratio of particles to 3-aminopropyltrimethoxysilane is 2:1 to 8:1. The modified silicon-oxygen anode material exhibits significantly improved mechanical strength, effectively alleviating the stress caused by volume changes during charge and discharge of the silicon-based anode material. This effectively suppresses the volume expansion of the silicon-based material, maintains the structural stability of the anode material during cycling, and demonstrates good interfacial stability, thereby further improving the cycle stability of the battery.

[0022] In a second aspect, the present invention also provides a negative electrode material for lithium batteries prepared by the above method, wherein the particle size range of the product is 3-10 μm, preferably 4-7 μm.

[0023] A third aspect of the present invention also provides a lithium-ion battery, comprising: a positive electrode, a negative electrode, a separator, and an electrolyte; the preparation method is as follows:

[0024] The above-mentioned negative electrode material is mixed with carbon black Super-P, carboxyl-containing binder CMC and SBR, and added to a solvent and mixed evenly to obtain a negative electrode slurry; the negative electrode slurry is coated onto copper foil, and after drying, rolling and cutting, a negative electrode sheet is obtained;

[0025] The negative electrode, positive electrode, and separator are assembled together, encapsulated, and injected with electrolyte to perform formation and capacity testing, thereby obtaining a lithium-ion battery.

[0026] Preferably, the preparation method of the carboxyl-containing adhesive CMC includes: adding vinyl ethylene carbonate to a styrene-butadiene polymerization system for reaction, wherein the amount of vinyl ethylene carbonate added is 50% to 60% of the total mass of the styrene-butadiene polymerization system; after the reaction is completed, diluting to a concentration of 1% to 5% and then adjusting the pH to neutral to obtain the carboxyl-containing adhesive.

[0027] Preferably, the cathode material is selected from one or more of the following: ternary cathode, lithium iron phosphate cathode, lithium manganese iron phosphate cathode, and lithium manganese oxide cathode.

[0028] More preferably, the positive electrode active material is one or more of the following: polycrystalline ternary positive electrode material, nano-lithium manganese iron phosphate positive electrode material, and spinel-type lithium manganese oxide positive electrode material.

[0029] Beneficial effects of the present invention

[0030] (1) In this invention, silicon-oxygen materials are coated and surface-modified with functional groups. By mixing modified silicon-oxygen materials with graphite anodes, anode materials for lithium batteries are prepared. The mechanical strength of the modified anode materials is significantly improved. At the same time, due to the introduction of functional groups, they can also work together to alleviate the stress changes of silicon-based anode materials, effectively suppress the volume expansion of silicon-based materials, maintain the structural stability of anode materials during cycling, and have good interface stability, thereby further improving the cycle stability of batteries.

[0031] (2) This invention uses one or more of the following materials as the positive electrode of a lithium-ion battery: polycrystalline ternary cathode material, nano-lithium manganese iron phosphate cathode material, and spinel-type lithium manganese oxide cathode material. Graphite and modified silicon oxide materials are combined to serve as the negative electrode of the lithium-ion battery. The battery is assembled using separators with different porosities and different types of electrolytes. After the formation and capacity test is completed, the charge and discharge test is performed, which significantly improves the battery cycle performance.

[0032] (3) Compared with existing TiO2 / SiO x Compared to composite materials, this invention has advantages in SiO2. x The modified silicon-oxygen anode material is prepared by first physically coating TiO2 onto the particle surface and then chemically modifying it with amino groups. This dual physical and chemical coating can more effectively suppress expansion and maintain excellent cycle performance. At the same time, the modified silicon-oxygen anode material contains amino groups, which can better combine with the carboxyl-containing binder CMC to improve the electrochemical performance of lithium batteries.

[0033] (4) The preparation method of the present invention is simple, practical and easy to promote. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. Exemplary embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0035] Figure 1 The amino-containing TiO2 / SiO2 prepared in Example 1 of this invention x SEM image of the particles;

[0036] Figure 2 The charge-discharge curves of the lithium-ion battery prepared in Example 1 are shown. Detailed Implementation

[0037] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0038] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are explanations of the present invention and not limitations thereof.

[0039] In the following examples, the preparation method of the carboxyl-containing adhesive CMC is as follows: at room temperature, vinyl ethylene carbonate is added to a styrene and butadiene polymerization system (styrene and butadiene are mixed in a mass ratio of 1:1) for reaction. The amount of vinyl ethylene carbonate added is 50% of the mass of the styrene and butadiene polymerization system. After the reaction is completed, the mixture is diluted to a concentration of 3% and then the pH is adjusted to neutral to obtain the carboxyl-containing adhesive.

[0040] Example 1:

[0041] A method for preparing a lithium-ion battery includes the following steps:

[0042] (a) Preparation of lithium-ion battery anode

[0043] 100g of silicon oxide compound SiO x The particles were placed in a 1000 mL mixture of hydrogen peroxide and sulfuric acid (sulfuric acid concentration 10% and hydrogen peroxide concentration 15%) and reacted thoroughly to obtain SiO₂ containing hydroxyl groups. x Particles, wherein the mass ratio of hydrogen peroxide to sulfuric acid is 2:1; treated SiO x The particle surface has a large number of hydroxyl groups attached, which are hydroxyl-containing silicon oxide compounds SiO x Add granules to 100g containing titanium tert-butoxide C 16 H 36 In an ethanol solution of O4Ti (where the mass concentration of titanium tert-butoxide is 10%), it is chemically bonded to C of titanium tert-butoxide. 16 H 36 The O4Ti structure is more tightly bonded. After uniform stirring, filtration, and vacuum drying, it is calcined at 600℃ for 4 hours in a tube furnace filled with inert gas to obtain TiO2 / SiO2. x Particles.

[0044] ② 100g of prepared TiO2 / SiO xThe particles were ultrasonically dispersed in deionized water, and 10% hydrochloric acid (HCl) was added to adjust the pH to approximately 3 for 1 hour. Then, 20 g of 3-aminopropyltrimethoxysilane was added dropwise to the acidic solution using a peristaltic pump. After the addition, the reaction was allowed to proceed for 12 hours. The mixture was then washed and dried by centrifugation with water and ethanol to obtain amino-containing TiO2 / SiO2. x Particles, i.e., modified silicon-oxygen anodes, as shown in SEM images. Figure 1 As shown.

[0045] A graphite anode and a modified silicon-oxygen anode were composited at a mass ratio of 95:5 to form a composite active material for the anode. The composite active material for the anode was then mixed with carbon black Super-P, a carboxyl-containing binder CMC, and SBR at a mass ratio of 96:1:1.3:1.7. The mixture was then added to pure water and stirred thoroughly to obtain a negative electrode slurry. The negative electrode slurry was coated onto a 6μm copper foil, and after drying, rolling, and cutting, a negative electrode sheet was obtained.

[0046] (b) Preparation of lithium-ion battery cathode

[0047] NCM positive electrode active material, conductive agent Super-P, carbon nanotube slurry (CNT), and binder PVDF are mixed in a mass ratio of 96.5:1:0.5:2 and added to solvent NMP through a multi-step process. After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is then coated onto a 12μm aluminum foil, and after drying, rolling, and die-cutting, a positive electrode sheet is obtained.

[0048] (c) Preparation of lithium-ion batteries

[0049] The prepared positive and negative electrode sheets from (a) and (b) were assembled with the separator, encapsulated, and injected with electrolyte. Formation and capacity testing were performed to obtain the desired lithium-ion battery, which was then subjected to charge-discharge tests. The voltage plateau was as follows: Figure 2 As shown.

[0050] Figure 2 The charging and discharging curves are shown at different rates. Compared with the charging and discharging at 0.33C, the polarization is greater and the charging voltage plateau is higher and the discharging voltage plateau is lower under the 1C high-rate charging and discharging condition.

[0051] Example 2:

[0052] A method for preparing a lithium-ion battery includes the following steps:

[0053] (a) Preparation of lithium-ion battery anode

[0054] The graphite anode and the modified silicon-oxygen anode from Example 1 were combined at a mass ratio of 92:8 to form the anode composite active material. The anode composite active material was mixed with carbon black Super-P, carboxyl-containing binder CMC and SBR at a mass ratio of 96:1:1.3:1.7 and added to pure water solvent to dissolve and stir fully to obtain anode slurry. The anode slurry was coated onto a 6μm copper foil, and after drying, rolling and cutting, anode sheets were obtained.

[0055] (b) Preparation of lithium-ion battery cathode

[0056] NCM positive electrode active material, conductive agent Super-P, carbon nanotube slurry (CNT), and binder PVDF are mixed in a mass ratio of 96.5:1:0.5:2 and added to solvent NMP through a multi-step process. After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is then coated onto a 12μm aluminum foil, and after drying, rolling, and die-cutting, a positive electrode sheet is obtained.

[0057] (c) Preparation of lithium-ion batteries

[0058] The positive and negative electrode sheets prepared in (a) and (b) are assembled with the separator, packaged and injected with electrolyte, and subjected to formation and capacity testing to obtain the desired lithium-ion battery and charge-discharge test.

[0059] Example 3:

[0060] A method for preparing a lithium-ion battery includes the following steps:

[0061] (a) Preparation of lithium-ion battery anode

[0062] The graphite anode and the modified silicon-oxygen anode from Example 1 were combined at a mass ratio of 90:10 to form the anode composite active material. The anode composite active material was mixed with carbon black Super-P, carboxyl-containing binder CMC and SBR at a mass ratio of 96:1:1.3:1.7 and added to pure water solvent to dissolve and stir fully to obtain anode slurry. The anode slurry was coated onto a 6μm copper foil, and after drying, rolling and cutting, anode sheets were obtained.

[0063] (b) Preparation of lithium-ion battery cathode

[0064] NCM positive electrode active material, conductive agent Super-P, carbon nanotube slurry (CNT), and binder PVDF are mixed in a mass ratio of 96.5:1:0.5:2 and added to solvent NMP through a multi-step process. After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is then coated onto a 12μm aluminum foil, and after drying, rolling, and die-cutting, a positive electrode sheet is obtained.

[0065] (c) Preparation of lithium-ion batteries

[0066] The positive and negative electrode sheets prepared in (a) and (b) are assembled with the separator, packaged and injected with electrolyte, and subjected to formation and capacity testing to obtain the desired lithium-ion battery and charge-discharge test.

[0067] Example 4:

[0068] A method for preparing a lithium-ion battery includes the following steps:

[0069] (a) Preparation of lithium-ion battery anode

[0070] The graphite anode and the modified silicon-oxygen anode from Example 1 were combined at a mass ratio of 85:15 to form the anode composite active material. The anode composite active material was mixed with carbon black Super-P, carboxyl-containing binder CMC and SBR at a mass ratio of 96:1:1.3:1.7 and added to pure water solvent to dissolve and stir fully to obtain anode slurry. The anode slurry was coated onto a 6μm copper foil, and after drying, rolling and cutting, anode sheets were obtained.

[0071] (b) Preparation of lithium-ion battery cathode

[0072] NCM positive electrode active material, conductive agent Super-P, carbon nanotube slurry (CNT), and binder PVDF are mixed in a mass ratio of 96.5:1:0.5:2 and added to solvent NMP through a multi-step process. After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is then coated onto a 12μm aluminum foil, and after drying, rolling, and die-cutting, a positive electrode sheet is obtained.

[0073] (c) Preparation of lithium-ion batteries

[0074] The positive and negative electrode sheets prepared in (a) and (b) are assembled with the separator, packaged and injected with electrolyte, and subjected to formation and capacity testing to obtain the desired lithium-ion battery and charge-discharge test.

[0075] Comparative Example 1

[0076] A method for preparing a lithium-ion battery includes the following steps:

[0077] (a) Preparation of lithium-ion battery anode

[0078] Graphite anode was used as the anode active material. The anode active material was mixed with carbon black Super-P, carboxyl-containing binder CMC and SBR in a mass ratio of 96:1:1.3:1.7. The mixture was added to pure water and stirred to obtain anode slurry. The anode slurry was coated onto a 6μm copper foil and then dried, rolled, and cut to obtain anode sheet.

[0079] (b) Preparation of lithium-ion battery cathode

[0080] NCM positive electrode active material, conductive agent Super-P, carbon nanotube slurry (CNT), and binder PVDF are mixed in a mass ratio of 96.5:1:0.5:2 and added to solvent NMP through a multi-step process. After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is then coated onto a 12μm aluminum foil, and after drying, rolling, and die-cutting, a positive electrode sheet is obtained.

[0081] (c) Preparation of lithium-ion batteries

[0082] The positive and negative electrode sheets prepared in (a) and (b) are assembled with the separator, packaged and injected with electrolyte, and subjected to formation and capacity testing to obtain the desired lithium-ion battery and charge-discharge test.

[0083] Comparative Example 2

[0084] A method for preparing a lithium-ion battery includes the following steps:

[0085] (a) Preparation of lithium-ion battery anode

[0086] A graphite anode and an unmodified silicon-oxygen anode were composited at a mass ratio of 95:5 to form a composite active material for the anode. The composite active material for the anode was then mixed with carbon black Super-P, a carboxyl-containing binder CMC, and SBR at a mass ratio of 96:1:1.3:1.7. The mixture was then added to pure water and stirred until fully dissolved to obtain a negative electrode slurry. The negative electrode slurry was coated onto a 6μm copper foil, and after drying, rolling, and cutting, a negative electrode sheet was obtained.

[0087] (b) Preparation of lithium-ion battery cathode

[0088] NCM positive electrode active material, conductive agent Super-P, carbon nanotube slurry (CNT), and binder PVDF are mixed in a mass ratio of 96.5:1:0.5:2 and added to solvent NMP through a multi-step process. After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is then coated onto a 12μm aluminum foil, and after drying, rolling, and die-cutting, a positive electrode sheet is obtained.

[0089] (c) Preparation of lithium-ion batteries

[0090] The positive and negative electrode sheets prepared in (a) and (b) are assembled with the separator, packaged and injected with electrolyte, and subjected to formation and capacity testing to obtain the desired lithium-ion battery and charge-discharge test.

[0091] Comparative Example 3

[0092] The difference from Example 1 is that a commercially available "adhesive CMC" is used instead of "carboxyl-containing adhesive CMC".

[0093] A method for preparing a lithium-ion battery includes the following steps:

[0094] (a) Preparation of lithium-ion battery anode

[0095] The graphite anode and the modified silicon-oxygen anode from Example 1 were combined at a mass ratio of 95:5 to form the anode composite active material. The anode composite active material was mixed with carbon black Super-P, conventional binder CMC and SBR at a mass ratio of 96:1:1.3:1.7 and added to pure water solvent to dissolve and stir fully to obtain anode slurry. The anode slurry was coated onto a 6μm copper foil, and after drying, rolling and cutting, anode sheets were obtained.

[0096] (b) Preparation of lithium-ion battery cathode

[0097] NCM positive electrode active material, conductive agent Super-P, carbon nanotube slurry (CNT), and binder PVDF are mixed in a mass ratio of 96.5:1:0.5:2 and added to solvent NMP through a multi-step process. After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is then coated onto a 12μm aluminum foil, and after drying, rolling, and die-cutting, a positive electrode sheet is obtained.

[0098] (c) Preparation of lithium-ion batteries

[0099] The positive and negative electrode sheets prepared in (a) and (b) are assembled with the separator, packaged and injected with electrolyte, and subjected to formation and capacity testing to obtain the desired lithium-ion battery and charge-discharge test.

[0100] Comparative Example 4

[0101] The difference from Example 1 is that the "TiO2 / SiO2" prepared using patent CN115332524A is used. x "Bulk bicontinuous structure electrode material" replaces the "TiO2 / SiO" prepared in Example 1. x Particles.

[0102] A method for preparing a lithium-ion battery includes the following steps:

[0103] (a) Preparation of lithium-ion battery anode

[0104] The graphite anode and the "TiO2 / SiOx bulk dual continuous structure electrode material" prepared by patent CN115332524A were combined at a mass ratio of 95:5 to form the anode composite active material. The anode composite active material was mixed with carbon black Super-P, carboxyl-containing binder CMC and SBR at a mass ratio of 96:1:1.3:1.7 and added to pure water solvent to fully dissolve and stir to obtain anode slurry. The anode slurry was coated onto a 6μm copper foil, and after drying, rolling and cutting, anode sheets were obtained.

[0105] (b) Preparation of lithium-ion battery cathode

[0106] NCM positive electrode active material, conductive agent Super-P, carbon nanotube slurry (CNT), and binder PVDF are mixed in a mass ratio of 96.5:1:0.5:2 and added to solvent NMP through a multi-step process. After thorough stirring, a positive electrode slurry is obtained. The positive electrode slurry is then coated onto a 12μm aluminum foil, and after drying, rolling, and die-cutting, a positive electrode sheet is obtained.

[0107] (c) Preparation of lithium-ion batteries

[0108] The positive and negative electrode sheets prepared in (a) and (b) are assembled with the separator, packaged and injected with electrolyte, and subjected to formation and capacity testing to obtain the desired lithium-ion battery and charge-discharge test.

[0109] The lithium-ion batteries in Examples 1-4 and Comparative Examples 1-4 were subjected to charge-discharge tests (long-cycle tests) under the following conditions: 25℃ & 100% DOD, 1C / 1C cycle, voltage range of 2.8~4.4V. The results are shown in the table below:

[0110] Table 1 Capacity Retention Rate of Lithium-ion Batteries

[0111] Capacity retention Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 100 weeks 99.5％ 99.8％ 99.2％ 98.9％ 98.2％ 97.1％ 97.5％ 96.3％ 200 weeks 98.8％ 99.1％ 98.2％ 96.7％ 95.4％ 93.8％ 94.3％ 92.4％ 500 weeks 94.9％ 95.3％ 93.7％ 91.4％ 89.5％ 85.9％ 86.6％ 85.1％ 1000 weeks 90.2％ 91.1％ 88.6％ 86.3％ 85.7％ 76.5％ 80.2％ 75.5％

[0112] A comparison of Example 1 and Comparative Example 1 shows that the addition of the modified silicon-oxygen anode significantly improves the battery's cycle performance. A comparison of Comparative Example 1 and Comparative Example 2 shows that the unmodified silicon-oxygen anode has negligible effect on suppressing expansion; adding the unmodified silicon-oxygen anode actually has a negative impact on battery cycle performance. Therefore, adding the unmodified graphite anode to the graphite anode is less effective than using a pure graphite anode. A comparison of Example 1 and Comparative Example 3 shows that using a "carboxyl-containing binder (CMC)" is more beneficial for improving battery cycle performance. A comparison of Example 1 and Comparative Example 4 shows that the TiO2 / SiO2 prepared in this invention... x Particles can better improve the cycle performance of batteries.

[0113] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a negative electrode material for lithium batteries, characterized in that, include: SiO x The particles react with a hydroxylating agent to obtain hydroxyl-modified SiO₂. x Particles; The hydroxyl-modified SiO₂ was treated with titanium tert-butoxide solution. x The particles are physically coated and calcined to obtain TiO2 / SiO2. x Particles; For the TiO2 / SiO x The particles were aminated to obtain a modified silicon-oxygen anode material; The modified silicon-oxygen anode material is combined with the graphite anode material at a mass ratio of 99:1-50:50 to obtain a composite active anode material. The hydroxyl-modified SiO x The mass ratio of particles to titanium tert-butoxide is 1:3-5:1; The hydroxylating agent is a mixture of hydrogen peroxide and sulfuric acid, wherein the mass ratio of hydrogen peroxide to sulfuric acid is 1:1-5:1; Or, the SiO x The mass ratio of the granules to the mixture of hydrogen peroxide and sulfuric acid is 1:10-3:1; The amination modification method is to modify the TiO2 / SiO2. x The particles react with 3-aminopropyltrimethoxysilane, wherein the TiO2 / Si ... x The mass ratio of the particles to 3-aminopropyltrimethoxysilane is 2:1 to 8:

1.

2. The method for preparing the negative electrode material for lithium batteries as described in claim 1, characterized in that, The mass ratio of the graphite anode material to the modified silicon-oxygen anode material is 98:2-80:20, or 95:5-85:

15.

3. The method for preparing the negative electrode material for lithium batteries as described in claim 1, characterized in that, The calcination conditions are calcination at 600℃-800℃ for 3-5 hours.

4. The negative electrode material for lithium batteries prepared by the method according to any one of claims 1-3.

5. A lithium-ion battery, characterized in that, include: Positive electrode, negative electrode, membrane, and electrolyte; The negative electrode material described in claim 4 is mixed with carbon black Super-P, a carboxyl-containing binder CMC, and SBR, and then added to a solvent and mixed evenly to obtain a negative electrode slurry; the negative electrode slurry is coated onto a copper foil, and after drying, rolling, and cutting, a negative electrode sheet is obtained; The negative electrode, positive electrode, and separator are assembled together, encapsulated, and injected with electrolyte to perform formation and capacity testing, thereby obtaining a lithium-ion battery.

6. The lithium-ion battery as described in claim 5, characterized in that, The preparation method of the carboxyl-containing binder CMC includes: adding vinyl ethylene carbonate to a styrene and butadiene polymerization system for reaction, wherein the amount of vinyl ethylene carbonate added is 50% to 60% of the total mass of the styrene and butadiene polymerization system; after the reaction is completed, dilution is performed, and then the pH is adjusted to neutral to obtain the carboxyl-containing binder.

7. The lithium-ion battery as described in claim 5, characterized in that, The positive electrode active material is one or more of the following: polycrystalline ternary positive electrode material, nano-lithium manganese iron phosphate positive electrode material, and spinel-type lithium manganese oxide positive electrode material.

Images