Silicon-based electrode active material, electrode composite active material, preparation method and use

Abstract

The present application relates to the technical field of secondary batteries, and in particular relates to a silicon-based electrode active material, an electrode composite active material, a preparation method and the use. The silicon-based electrode active material comprises silicon-based particles, a bonding layer and an electrically conductive substance, wherein the conductivity of the electrically conductive substance is larger than that of the silicon-based particles, and the electrically conductive substance is attached to the silicon-based particles by means of the bonding layer and can be kept attached to the silicon-based particles during the expansion and shrinkage process of the silicon-based particles.

Description

Silicon-based electrode active materials, electrode composite active materials, preparation methods and applications

[0001] Related applications

[0002] This application claims priority to Chinese patent application filed on December 31, 2024, application number 2024120001049, entitled "Silicon-based electrode active material, electrode composite active material, preparation method and application", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of secondary battery technology, and in particular to a silicon-based electrode active material, an electrode composite active material, a preparation method, and an application. Background Technology

[0004] As electronic devices strive for longer battery life and thinner, higher demands are being placed on battery energy density. Traditional graphite materials have a theoretical specific capacity of 372 mAh / g, which is relatively low, and current technology has already approached the theoretical value. Therefore, continuing to use traditional graphite anode systems limits further improvements in battery energy density, necessitating the development of next-generation anode materials.

[0005] Silicon has a theoretical specific capacity of 4200 mAh / g, making it the most promising anode material for next-generation high-energy-density batteries. However, its cycle performance is poor and cannot meet market demands. Summary of the Invention

[0006] Based on this, this application provides a silicon-based electrode active material, an electrode composite active material, a preparation method, and an application.

[0007] The first aspect of this application provides a silicon-based electrode active material, the technical solution of which is as follows:

[0008] A silicon-based electrode active material includes silicon-based particles, an adhesive layer, and a conductive material. The conductive material has a higher conductivity than the silicon-based particles. The conductive material is attached to the silicon-based particles through the adhesive layer and is able to remain attached to the silicon-based particles during their expansion and contraction.

[0009] A second aspect of this application provides an electrode composite active material, the technical solution of which is as follows:

[0010] An electrode composite active material includes a silicon-based electrode active material and active particles as described above. The active particles are independently and freely dispersed in the gaps between the silicon-based electrode active material, or are covered by the adhesive layer, or are connected to the silicon-based particles through the adhesive layer.

[0011] A third aspect of this application provides a method for preparing a silicon-based electrode active material, the technical solution of which is as follows:

[0012] A method for preparing a silicon-based electrode active material includes the following steps:

[0013] Silicon-based particles and a conductive material are mixed to obtain a dry powder mixture, wherein the conductivity of the conductive material is greater than that of the silicon-based particles;

[0014] The dry powder mixture, binder and solvent are mixed to obtain a slurry with a solid content of 50wt% to 90wt%.

[0015] After diluting the slurry, the solvent is removed, allowing the adhesive material to form an adhesive layer. This adhesive layer attaches the conductive material to the silicon-based particles and enables the conductive material to remain attached to the silicon-based particles during their expansion and contraction.

[0016] The fourth aspect of this application provides a method for preparing an electrode composite active material, the technical solution of which is as follows:

[0017] A method for preparing an electrode composite active material includes the following steps: mixing a silicon-based electrode active material and active particles, wherein the silicon-based electrode active material is prepared as described above, or by the preparation method described above.

[0018] The fifth aspect of this application provides a method for preparing an electrode composite active material, the technical solution of which is as follows:

[0019] A method for preparing an electrode composite active material includes the following steps:

[0020] A dry powder mixture is obtained by mixing silicon-based particles, a portion of active particles, and a conductive material, wherein the conductivity of the conductive material is greater than that of the silicon-based particles.

[0021] The dry powder mixture, binder and solvent are mixed to obtain a slurry with a solid content of 50wt% to 90wt%.

[0022] After diluting the slurry, the solvent is removed, allowing the binder material to form a binder layer. The binder layer attaches the conductive material to the silicon-based particles, ensuring that the conductive material remains attached to the silicon-based particles during their expansion and contraction. The active particles are either coated by the binder layer or connected to the silicon-based particles through the binder layer, or connected to the conductive material through the binder layer, thus obtaining a premixed powder.

[0023] Mix the premixed powder with the remaining portion of the active particles.

[0024] The sixth aspect of this application provides a method for preparing an electrode composite active material, the technical solution of which is as follows:

[0025] A method for preparing an electrode composite active material includes the following steps:

[0026] A dry powder mixture is obtained by mixing silicon-based particles, active particles, and a conductive material, wherein the conductivity of the conductive material is greater than that of the silicon-based particles.

[0027] The dry powder mixture, binder and solvent are mixed to obtain a slurry with a solid content of 50wt% to 90wt%.

[0028] After diluting the slurry, the solvent is removed, allowing the adhesive material to form an adhesive layer. The adhesive layer attaches the conductive material to the silicon-based particles and enables the conductive material to remain attached to the silicon-based particles during their expansion and contraction. The active particles are either coated by the adhesive layer or connected to the silicon-based particles through the adhesive layer, or connected to the conductive material through the adhesive layer.

[0029] The seventh aspect of this application provides an electrode sheet, the technical solution of which is as follows:

[0030] An electrode electrode includes a current collector and an electrode active layer located on the current collector. The electrode active layer includes a silicon-based electrode active material as described above, or an electrode composite active material as described above, or a silicon-based electrode active material prepared by the preparation method as described above, or an electrode composite active material prepared by the preparation method as described above.

[0031] This application provides a battery in an eighth aspect, the technical solution of which is as follows:

[0032] A battery includes a positive electrode, a negative electrode, and a separator, wherein the separator is located between the positive electrode and the negative electrode. The negative electrode may be as described above, or may include a silicon-based electrode active material as described above, or may include an electrode composite active material as described above, or may include a silicon-based electrode active material prepared by the preparation method described above, or may include an electrode composite active material prepared by the preparation method described above.

[0033] Details of one or more embodiments of this application are set forth in the following description, and other features, objects, and advantages of this application will become apparent from the specification and its claims. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 is a schematic diagram of the structure of a silicon-based electrode active material according to one embodiment;

[0036] Figure 2 is a schematic diagram of the structure of an electrode composite active material according to one embodiment;

[0037] Figure 3 is a SEM image of the silicon-based electrode active material of Example 1;

[0038] Figure 4 is a SEM image of the premixed powder of Example 4;

[0039] Figure 5 is a SEM image of the electrode sheet of Example 1 before coin cell cycling;

[0040] Figure 6 is a SEM image of the electrode of Example 1 after coin cell cycling. Detailed Implementation

[0041] The present application will be further described in detail below with reference to specific embodiments. The present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0043] the term

[0044] Unless otherwise stated or in case of conflict, the terms or phrases used in this application shall have the following meanings:

[0045] In this application, the terms "optionally," "optionally," and "optional" refer to options that are optional, meaning they can be selected from either "with" or "without." If multiple "optional" options appear in a technical solution, unless otherwise specified and there are no contradictions or mutual constraints, each "optional" option is independent.

[0046] In this application, the terms "first aspect," "second aspect," "third aspect," and "fourth aspect," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first," "second," "third," and "fourth," etc., serve only a non-exhaustive enumeration purpose and should be understood not to constitute a closed limitation on quantity.

[0047] In this application, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0048] In this application, when an element is referred to as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. It should also be understood that, in interpreting the connection or positional relationship of elements, although not explicitly described, connection and positional relationships are interpreted to include a range of error, which should be within the acceptable deviation range of a specific value as determined by a person skilled in the art.

[0049] The first aspect of this application provides a silicon-based electrode active material. In one embodiment, the silicon-based electrode active material includes silicon-based particles, an adhesive layer, and a conductive material. The conductive material has a higher conductivity than the silicon-based particles. The conductive material is attached to the silicon-based particles through the adhesive layer and is able to remain attached to the silicon-based particles during the expansion and contraction of the silicon-based particles.

[0050] The inventors discovered that the cycling performance of silicon-based electrodes is related to the instability of the conductive connections between the active materials of the silicon-based electrodes. Specifically, silicon-based electrode active materials are typically blended with active particles, with the active particles filling the gaps between the active materials. During charge and discharge, the active materials of the silicon-based electrodes undergo significant expansion and contraction, creating large gaps between them and the surrounding active particles. These gaps lead to increased polarization, and in some cases, the active materials of the silicon-based electrodes may completely lose their conductive connections, losing their lithium storage activity, resulting in decreased kinetic performance, reduced capacity, and even lithium plating. Based on these findings, the above-described embodiment introduces a conductive material with a conductivity greater than that of the silicon-based particles into the active material of the silicon-based electrodes through a bonding layer. This conductive material not only adheres to the silicon-based particles but also remains attached to them during the expansion and contraction of the silicon-based particles during charge and discharge. This conductive material acts as a bridge, enabling stable conductive connections between the active materials of the silicon-based electrodes during charge and discharge. Simultaneously, the conductive material can also bridge the gaps between the silicon-based particles and the active particles, enhancing their conductive connection. The silicon-based electrode active material described above exhibits good lithium storage activity and kinetic performance, and has a high capacity retention rate during charge-discharge cycles.

[0051] In the above embodiments, the adhesive layer can prevent the conductive material from detaching from the silicon-based particles. The conductive material can be attached to the silicon-based particles in various ways. Optionally, the adhesive layer covers the silicon-based particles. Optionally, the conductive material is independently dispersed within the adhesive layer, located on the surface of the adhesive layer, or covered by the adhesive layer.

[0052] Please refer to Figure 1, which is a schematic diagram of the structure of a silicon-based electrode active material according to an embodiment. The silicon-based electrode active material 100 includes silicon-based particles 11, an adhesive layer 12, and a conductive material 13. The adhesive layer 12 covers the silicon-based particles 11, and the conductive material 13 is independently located on the outer surface of the adhesive layer 12.

[0053] Optionally, the silicon-based particles comprise silicon and other elements, and optionally, the silicon content is 5 wt% to 95 wt%. For example, the silicon content is 5 wt%, 10 wt%, 25 wt%, 50 wt%, 65 wt%, 80 wt%, or 95 wt%. Optionally, the other elements include one or more of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, boron, copper, silver, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron. The sum of the silicon content and the content of the other elements is 100%.

[0054] Optionally, the particle size D50 of the silicon-based particles satisfies: 0.1 μm ≤ D50 ≤ 30 μm. For example, the particle size D50 is 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, or 30 μm. The silicon-based particles may be spherical.

[0055] Optionally, the conductive material accounts for 0.04% to 50% of the mass of the silicon-based electrode active material. For example, the percentages are 0.04%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, and 50%.

[0056] Optionally, the conductive material includes one or more of conductive carbon black, carbon nanotubes, graphene, carbon fibers, copper nanoparticles, and silver nanoparticles.

[0057] The size of the conductive material can be adjusted and selected according to its shape. Optionally, the conductive material is irregularly shaped, with a particle size D50 satisfying: 0.01μm ≤ D50 ≤ 10μm. For example, the particle size D50 is 0.5μm, 1μm, 5μm, or 10μm. Optionally, the conductive material is nearly spherical, with a particle size D50 satisfying: 0.01μm ≤ D50 ≤ 10μm. For example, the particle size D50 is 0.5μm, 1μm, 5μm, or 10μm. Optionally, the conductive material is fibrous or tubular, with an average length L satisfying: 0.5μm ≤ D50 ≤ 100μm, and an aspect ratio L / D satisfying: 1 ≤ D50 ≤ 200000. For example, the length L is 0.5μm, 1μm, 5μm, 10μm, 50μm, or 100μm. The aspect ratio L / D is 1, 10, 100, 1000, 10000, 100000, or 200000. Optionally, the conductive material is in sheet form with a thickness h satisfying: 0.1 nm ≤ h ≤ 10 μm. For example, the thickness h is 0.1 nm, 1 nm, 10 nm, 100 nm, 1 μm, or 10 μm. The maximum distance L1 between two points on the front side satisfies: 0.05 μm ≤ L1 ≤ 100 μm. For example, L1 is 0.05 μm, 0.5 μm, 5 μm, 50 μm, or 100 μm. The maximum distance L2 between two points on the back side satisfies: 0.05 μm ≤ L2 ≤ 100 μm. For example, L2 is 0.05 μm, 0.5 μm, 5 μm, 50 μm, or 100 μm. Optionally, the conductive material is in the form of a strip, with a thickness h satisfying: 0.1 nm ≤ h ≤ 10 μm, and an average length L satisfying: 0.05 μm ≤ L ≤ 100 μm. For example, L can be 0.05 μm, 0.5 μm, 5 μm, 50 μm, or 100 μm. The average width W satisfies: 1 nm ≤ W ≤ 50 μm. For example, the average width W can be 1 nm, 10 nm, 100 nm, 1 μm, 10 μm, or 50 μm.

[0058] Optionally, the mass of the adhesive layer accounts for 0.04% to 50% of the mass of the silicon-based electrode active material. For example, the percentages are 0.04%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, and 50%.

[0059] Optionally, the adhesive layer may be made of one or more of a polymeric adhesive material, a partially carbide of the polymeric adhesive material, and a fully carbide of the polymeric adhesive material. The partially carbide and fully carbide of the polymeric adhesive material are formed by heating and carbonizing part or all of the polymeric adhesive material.

[0060] Optionally, the structure of the polymeric adhesive material includes one or more of the following: acrylate groups, carboxylic acid groups, cyano groups, amide groups, hydroxyl groups, benzene rings, carbon-carbon double bonds, carbon-carbon triple bonds, pyrrole, amino groups, and imine groups. For example, the polymeric adhesive material includes one or more of PAA (polyacrylic acid), CMC (carboxymethyl cellulose), SBR (styrene-butadiene rubber), PAN (polyacrylonitrile), PAM (polyacrylamide), PVA (polyvinyl alcohol), PPy (polypyrrole), and PANI (polyaniline). The aforementioned polymeric adhesive material can be a conductive polymeric adhesive material, a semi-conductive polymeric adhesive material, or an insulating polymeric adhesive material.

[0061] Optionally, the specific surface area of ​​the silicon-based electrode active material is ≤30m². 2 / g. For example, a specific surface area of ​​5m². 2 / g, 10m 2 / g, 15m 2 / g、20m 2 / g、25m 2 / g、30m 2 / g.

[0062] Optionally, the primary particle size D10 of the silicon-based electrode active material satisfies: 0.01 μm ≤ D10 ≤ 50 μm. The particle size D50 satisfies: 0.01 μm ≤ D50 ≤ 50 μm. The particle size D90 satisfies: 0.01 μm ≤ D90 ≤ 50 μm. For example, D10 can be 0.01 μm, 1 μm, 10 μm, or 50 μm. D50 can be 0.01 μm, 1 μm, 10 μm, or 50 μm. D90 can be 0.01 μm, 1 μm, 10 μm, or 50 μm.

[0063] Optionally, the particle size D50 of the secondary particles of the silicon-based electrode active material satisfies: 0.15μm≤D50≤100μm. For example, D50 is 0.15μm, 0.2μm, 0.5μm, 1μm, 5μm, 10μm, 20μm, 30μm, 50μm, 80μm, or 100μm.

[0064] Optionally, the resistivity of the silicon-based electrode active material is 0.5 Ω·mm to 1500 Ω·mm. For example, the resistivity is 0.5 Ω·mm, 1 Ω·mm, 10 Ω·mm, 100 Ω·mm, 1000 Ω·mm, or 1500 Ω·mm.

[0065] Optionally, the silicon-based electrode active material is a silicon-based negative electrode active material.

[0066] A second aspect of this application provides an electrode composite active material. In one embodiment, the electrode composite active material includes a silicon-based electrode active material and active particles as described above. This is beneficial for further improving the electrochemical performance of the silicon-based electrode active material. Optionally, the active particles are independently and freely dispersed in the gaps between the silicon-based electrode active material, or are coated by the adhesive layer, or are connected to the silicon-based particles through the adhesive layer, or are connected to the conductive material through the adhesive layer.

[0067] The active particles possess a certain theoretical specific capacity and high conductivity. Their addition further enhances the stability of the conductive connection. The active particles can exist in various forms. Understandably, the active particles are freely dispersed in the gaps between the silicon-based electrode active material, meaning that the active particles can have intervals or direct contact with the silicon-based particles, and their position is not restricted. This state can be achieved by co-blending the silicon-based electrode active material and the active particles. Furthermore, the active particles can also be coated by the adhesive layer, or connected to the silicon-based particles through the adhesive layer, or connected to the conductive material through the adhesive layer. In this case, it can be achieved by preparing a premixed powder.

[0068] The active particles are coated with a binder layer. This binder layer can coat the active particles alone or simultaneously coat both the silicon-based particles and the active particles. Coating both silicon-based and active particles simultaneously is equivalent to "binding" them together. This "binding" creates a direct conductive connection between them. During charging and discharging, the expanding silicon-based material maintains this conductive connection with the active particles. Furthermore, because the active particles have a low expansion rate in a certain direction when fully lithium-intercalated, they are better able to maintain electrical connectivity with the surrounding system in that direction, thus providing a more stable conductive structure to maintain capacity retention and kinetic performance during cycling. This effect is also beneficial when the active particles are connected to the silicon-based particles via the binder layer. Similarly, the effect is also beneficial when the active particles are connected to a conductive material via the binder layer, and vice versa.

[0069] Optionally, the adhesive layer covers both the silicon-based particles and the active particles. When the adhesive layer covers both the silicon-based particles and the active particles, the conductive connection between them is more stable, and the conductive material can still adhere to the silicon-based particles in various ways. Optionally, the conductive material is independently dispersed within the adhesive layer, located on the surface of the adhesive layer, or covered by the adhesive layer.

[0070] Please refer to Figure 2, which is a schematic diagram of the structure of an electrode composite active material according to one embodiment. The electrode composite active material 200 includes silicon-based particles 21, a binder layer 22, a conductive material 23, and active particles 24. The binder layer 22 covers the silicon-based particles 21 and the active particles 24, and the conductive material 23 is independently located on the outer surface of the binder layer 22.

[0071] Optionally, each of the active particles satisfies the following conditions:

[0072] 1) The theoretical specific capacity of the active particles is ≥100mAh / g;

[0073] 2) The conductivity of the active particles is greater than that of the silicon-based particles;

[0074] 3) The expansion rate of the active particles in a certain direction under the fully lithium-intercalated state is less than the expansion rate of the silicon-based particles in that direction under the fully lithium-intercalated state.

[0075] Optionally, the active particles account for 1% to 95% of the mass of the silicon-based electrode active material. For example, 1%, 25%, 50%, 75%, and 95%.

[0076] Optionally, the active particles include one or more of the following: artificial graphite, natural graphite, hard carbon, soft carbon, carbon microspheres, lithium metal, lithium titanate, silicon-based materials, and tin-based materials. Understandably, when the active particles are silicon-based materials, the elements or content of the silicon-based materials differ from those of the silicon-based particles.

[0077] Optionally, the particle size D50 of the active particles satisfies: 0.1 μm ≤ D50 ≤ 50 μm. For example, D50 is 0.1 μm, 0.5 μm, 1 μm, 5 μm, 10 μm, 20 μm, 30 μm, or 50 μm. The active particles may be spherical.

[0078] Understandably, the electrode composite active material is a negative electrode composite active material.

[0079] A third aspect of this application provides a method for preparing a silicon-based electrode active material. In one embodiment, the method for preparing the silicon-based electrode active material includes the following steps:

[0080] Silicon-based particles and conductive materials are mixed to obtain a dry powder mixture;

[0081] The dry powder mixture, binder and solvent are mixed to obtain a slurry with a solid content of 50wt% to 90wt%.

[0082] After diluting the slurry, the solvent is removed, allowing the adhesive material to form an adhesive layer. The adhesive layer attaches the conductive material to the silicon-based particles and enables the conductive material to remain attached to the silicon-based particles during their expansion and contraction. The conductive material has a higher conductivity than the silicon-based particles.

[0083] In the process of mixing raw materials, mixing dry powder first and then controlling the solid content of slurry is beneficial to preparing silicon-based electrode active materials with good adhesion of conductive materials, and also beneficial to the adhesion of conductive materials during the expansion and contraction of silicon-based particles.

[0084] The solid content of the slurry can be 50wt%, 60wt%, 70wt%, 80wt%, or 90wt%. This range of solid content is conducive to the thorough mixing of the raw materials and the formation of a bonding layer.

[0085] The silicon-based particles and conductive materials are described above and will not be repeated here.

[0086] Optionally, the structure of the adhesive material includes one or more of the following: acrylate groups, carboxylic acid groups, cyano groups, amide groups, hydroxyl groups, benzene rings, carbon-carbon double bonds, carbon-carbon triple bonds, pyrrole, amino groups, and imine groups. For example, polymeric adhesive materials include one or more of PAA (polyacrylic acid), CMC (carboxymethyl cellulose), SBR (styrene-butadiene rubber), PAN (polyacrylonitrile), PAM (polyacrylamide), PVA (polyvinyl alcohol), PPy (polypyrrole), and PANI (polyaniline). The aforementioned polymeric adhesive materials can be conductive, semi-conductive, or insulating.

[0087] Optionally, the mass of the binder material accounts for 0.04% to 50% of the mass of the silicon-based electrode active material. For example, the percentages are 0.04%, 0.5%, 1%, 2%, 5%, 10%, 15%, 20%, 25%, 30%, 40%, and 50%.

[0088] Optionally, the solvent includes water. Optionally, the method for removing the solvent includes spray drying. Optionally, prior to spray drying, the method further includes the step of diluting the slurry to a solid content of 1 wt% to 50 wt%. For example, diluting to solid contents of 1 wt%, 5 wt%, 10 wt%, 20 wt%, 30 wt%, 40 wt%, or 50 wt%. The above solid content ranges are advantageous for spray drying. It is understood that the diluent solvent can be removed by spray drying. Optionally, the diluent includes water.

[0089] After removing the solvent, the binder material can form a binder layer, which at this point does not contain carbides. Optionally, after removing the solvent, the process further includes heating to partially or completely carbonize the binder material to form the binder layer. Heating causes partial or complete carbonization of the binder material, forming carbides, at which point the binder layer includes partial or complete carbides. The inclusion of partial or complete carbides in the binder layer is more beneficial for improving the conductivity of the electrode active material.

[0090] The degree of carbonization of the adhesive layer is related to the heating temperature. Optionally, the heating temperature is 60℃ to 700℃. For example, the heating temperatures are 60℃, 100℃, 200℃, 300℃, 400℃, 500℃, 600℃, and 700℃.

[0091] The fourth aspect of this application provides a method for preparing an electrode composite active material. In one embodiment, the method for preparing the electrode composite active material includes the following steps: mixing a silicon-based electrode active material and active particles, wherein the silicon-based electrode active material is prepared as described above or by the preparation method described above.

[0092] The active particles have a certain theoretical specific capacity and high conductivity. The addition of active particles can further enhance the stability of the conductive connection.

[0093] Optionally, the active particles account for 1% to 95% of the mass of the silicon-based electrode active material. For example, 1%, 25%, 50%, 75%, and 95%.

[0094] The fifth aspect of this application provides a method for preparing an electrode active composite material. In one embodiment, the method for preparing the electrode composite active material includes the following steps:

[0095] A method for preparing an electrode composite active material includes the following steps:

[0096] A dry powder mixture is obtained by mixing silicon-based particles, a portion of active particles, and a conductive material, wherein the conductivity of the conductive material is greater than that of the silicon-based particles.

[0097] The dry powder mixture, binder and solvent are mixed to obtain a slurry with a solid content of 50wt% to 90wt%.

[0098] After diluting the slurry, the solvent is removed, allowing the binder material to form a binder layer. The binder layer attaches the conductive material to the silicon-based particles, ensuring that the conductive material remains attached to the silicon-based particles during their expansion and contraction. The active particles are either coated by the binder layer or connected to the silicon-based particles through the binder layer, or connected to the conductive material through the binder layer, thus obtaining a premixed powder.

[0099] Mix the premixed powder with the remaining portion of the active particles.

[0100] Compared to blending silicon-based electrode active materials and active particles, the preparation of the above-mentioned premixed powder can more tightly bond a portion of the active particles, silicon-based particles, and conductive materials, so that a portion of the active particles are coated by the adhesive layer, or connected to the silicon-based particles through the adhesive layer, or connected to the conductive materials through the adhesive layer.

[0101] After removing the solvent, the binder material can form an adhesive layer, which at this point does not contain carbides. Optionally, after removing the solvent, the process further includes heating to partially or completely carbonize the binder material to form the adhesive layer. Heating causes partial or complete carbonization of the binder material, forming carbides, at which point the adhesive layer includes partial or complete carbides. The inclusion of partial or complete carbides in the adhesive layer is more beneficial for improving the electrical conductivity of the premixed powder.

[0102] Optionally, the active particles account for 1% to 95% of the total mass of the silicon-based particles, the binder layer, and the conductive material. For example, 1%, 25%, 50%, 75%, and 95%.

[0103] Optionally, the particle size D10 of the primary particles of the premixed powder satisfies: 0.01 μm ≤ D10 ≤ 50 μm. The particle size D50 satisfies: 0.01 μm ≤ D50 ≤ 50 μm. The particle size D90 satisfies: 0.01 μm ≤ D90 ≤ 50 μm. For example, D10 can be 0.01 μm, 1 μm, 10 μm, or 50 μm. D50 can be 0.01 μm, 1 μm, 10 μm, or 50 μm. D90 can be 0.01 μm, 1 μm, 10 μm, or 50 μm.

[0104] Optionally, the resistivity of the premixed powder is 0.5 Ω·mm to 1500 Ω·mm. For example, the resistivity is 0.5 Ω·mm, 1 Ω·mm, 10 Ω·mm, 100 Ω·mm, 1000 Ω·mm, or 1500 Ω·mm.

[0105] Understandably, other information regarding the active particles is as described above and will not be repeated here. Silicon-based particles, conductive materials, and binders are also described above and will not be repeated here. Except for the addition of active particles, the other steps follow the same method as described above for preparing silicon-based electrode active materials and will not be repeated here.

[0106] The sixth aspect of this application provides a method for preparing an electrode composite active material. In one embodiment, the method for preparing the electrode composite active material includes the following steps:

[0107] A dry powder mixture is obtained by mixing silicon-based particles, active particles, and a conductive material, wherein the conductivity of the conductive material is greater than that of the silicon-based particles.

[0108] The dry powder mixture, binder and solvent are mixed to obtain a slurry with a solid content of 50wt% to 90wt%.

[0109] After diluting the slurry, the solvent is removed, allowing the adhesive material to form an adhesive layer. The adhesive layer attaches the conductive material to the silicon-based particles and enables the conductive material to remain attached to the silicon-based particles during their expansion and contraction. The active particles are either coated by the adhesive layer or connected to the silicon-based particles through the adhesive layer, or connected to the conductive material through the adhesive layer.

[0110] Compared to blending silicon-based electrode active materials and active particles, the preparation of the above-mentioned electrode composite active material can more tightly bond the active particles, silicon-based particles and conductive materials, so that the active particles are coated by the adhesive layer, or connected to the silicon-based particles through the adhesive layer, or connected to the conductive material through the adhesive layer.

[0111] After removing the solvent, the binder material can form a binder layer, which at this point does not contain carbides. Optionally, after removing the solvent, the process further includes heating to partially or completely carbonize the binder material to form the binder layer. Heating causes partial or complete carbonization of the binder material, forming carbides, at which point the binder layer includes partial or complete carbides. The inclusion of partial or complete carbides in the binder layer is more beneficial for improving the conductivity of the electrode composite active material.

[0112] Optionally, the active particles account for 1% to 95% of the total mass of the silicon-based particles, the binder layer, and the conductive material. For example, 1%, 25%, 50%, 75%, and 95%.

[0113] Optionally, the primary particle size D10 of the electrode composite active material satisfies: 0.01 μm ≤ D10 ≤ 50 μm. The particle size D50 satisfies: 0.01 μm ≤ D50 ≤ 50 μm. The particle size D90 satisfies: 0.01 μm ≤ D90 ≤ 50 μm. For example, D10 can be 0.01 μm, 1 μm, 10 μm, or 50 μm. D50 can be 0.01 μm, 1 μm, 10 μm, or 50 μm. D90 can be 0.01 μm, 1 μm, 10 μm, or 50 μm.

[0114] Optionally, the resistivity of the electrode composite active material is 0.5 Ω·mm to 1500 Ω·mm. For example, the resistivity is 0.5 Ω·mm, 1 Ω·mm, 10 Ω·mm, 100 Ω·mm, 1000 Ω·mm, or 1500 Ω·mm.

[0115] Understandably, other information regarding the active particles is as described above and will not be repeated here. Silicon-based particles, conductive materials, and binders are also described above and will not be repeated here. Except for the addition of active particles, the other steps follow the same method as described above for preparing silicon-based electrode active materials and will not be repeated here.

[0116] The seventh aspect of this application provides an electrode sheet. In one embodiment, the electrode sheet includes a current collector and an electrode active layer located on the current collector. The electrode active layer includes a silicon-based electrode active material as described above, or an electrode composite active material as described above, or a silicon-based electrode active material prepared by the preparation method as described above, or an electrode composite active material prepared by the preparation method as described above.

[0117] Optionally, the electrode active layer further includes a conductive agent and a binder. The conductive agent fills the gaps between the silicon-based electrode active materials, making the flow of current smoother. Optionally, the conductive agent includes SP, CNT, and graphene. Optionally, the binder includes PAA.

[0118] Understandably, the electrode plate is a negative electrode plate.

[0119] The eighth aspect of this application provides a battery. In one embodiment, the battery includes a positive electrode, a negative electrode, and a separator, the separator being located between the positive electrode and the negative electrode. The negative electrode may be as described above, or may include a silicon-based electrode active material as described above, or may include an electrode composite active material as described above, or may include a silicon-based electrode active material prepared by the preparation method described above, or may include an electrode composite active material prepared by the preparation method described above.

[0120] Understandably, the battery can be a lithium-ion battery.

[0121] The following description is further illustrated with specific embodiments and comparative examples. Unless otherwise specified, the raw materials involved in the following specific embodiments and comparative examples are all commercially available. Unless otherwise specified, the instruments used are all commercially available. Unless otherwise specified, the processes involved are conventionally selected by those skilled in the art.

[0122] Among them, silicon-based materials are silicon-based particles. Silicon-based anode materials are silicon-based electrode active materials. Anode composite active materials are electrode composite active materials.

[0123] Example 1

[0124] This embodiment provides a silicon-based anode material, an anode composite active material, and a method for preparing the same, with the following steps:

[0125] Step 1: Add 100g of silicon-based material and 1g of conductive carbon black to a mixer and mix the dry powders for 30 minutes to obtain a dry powder mixture.

[0126] Step 2: Add 5g of 10wt% PAA aqueous solution, 25g of 0.4wt% CNT aqueous solution and 50g of pure water to the dry powder mixture, knead and stir for 30 minutes to obtain a slurry with a solid content of 65wt%.

[0127] Step 3: Add pure water to the slurry to dilute it to a solid content of 15 wt%, and then spray dry it to obtain a solid powder.

[0128] Step 4: Heat the solid powder at 100℃ for 2 hours, and after cooling, obtain silicon-based anode active material 1.

[0129] Step 5: Mix silicon-based anode active material 1 with graphite at a mass ratio of 10:90 to obtain anode composite active material 1.

[0130] Example 2

[0131] This embodiment provides a silicon-based anode material, an anode composite active material, and a method for preparing the same, with the following steps:

[0132] Step 1: Add 100g of silicon-based material and 1g of conductive carbon black to a mixer and mix the dry powders for 30 minutes to obtain a dry powder mixture.

[0133] Step 2: Add 5g of 10wt% PAA aqueous solution, 25g of 0.4wt% CNT aqueous solution and 50g of pure water to the dry powder mixture, knead and stir for 30 minutes to obtain a slurry with a solid content of 65wt%.

[0134] Step 3: Add 300g of pure water to the slurry and dilute it to a solid content of 15wt%. Then spray dry to obtain solid powder.

[0135] Step 4: Heat the solid powder at 500℃ for 2 hours, and after cooling, obtain silicon-based anode active material 2.

[0136] Step 5: Mix silicon-based anode active material 2 with graphite at a mass ratio of 10:90 to obtain anode composite active material 2.

[0137] Example 3

[0138] This embodiment provides a silicon-based anode material, an anode composite active material, and a method for preparing the same, with the following steps:

[0139] Step 1: Add 100g of silicon-based material and 1g of carbon nanofiber to a mixer and mix the dry powder for 30 minutes to obtain a dry powder mixture.

[0140] Step 2: Add 5g of 10wt% PAA aqueous solution, 5g of 2wt% graphene aqueous solution and 50g of pure water to the dry powder mixture, knead and stir for 30 minutes to obtain a slurry with a solid content of 65wt%.

[0141] Step 3: Add pure water to the slurry to dilute it to a solid content of 15 wt%, and then spray dry it to obtain a solid powder.

[0142] Step 4: Heat the solid powder at 500℃ for 2 hours, and after cooling, obtain silicon-based anode active material 3.

[0143] Step 5: Mix silicon-based anode active material 3 with graphite at a mass ratio of 10:90 to obtain anode composite active material 3.

[0144] Example 4

[0145] This embodiment provides a negative electrode composite active material and its preparation method, the steps of which are as follows:

[0146] Step 1: Add 50g of silicon-based material, 50g of graphite and 1g of conductive carbon black to a mixer and mix the dry powders for 30 minutes to obtain a dry powder mixture.

[0147] Step 2: Add 5g of 10wt% PAA aqueous solution, 25g of 0.4wt% CNT aqueous solution and 50g of pure water to the dry powder mixture, knead and stir for 30 minutes to obtain a slurry with a solid content of 65wt%.

[0148] Step 3: Add pure water to the slurry to dilute it to a solid content of 15 wt%, and then spray dry it to obtain a solid powder.

[0149] Step 4: Heat the solid powder at 100℃ for 2 hours, and then cool it to obtain premixed powder 4.

[0150] Step 5: Mix the premixed powder 4 with graphite at a mass ratio of 20:80 to obtain the negative electrode composite active material 4.

[0151] Example 5

[0152] This embodiment provides a negative electrode composite active material and its preparation method, the steps of which are as follows:

[0153] Step 1: Add 30g of silicon-based material, 70g of hard carbon and 0.5g of conductive carbon black to a mixer and mix the dry powders for 30 minutes to obtain a dry powder mixture.

[0154] Step 2: Add 5g of 10wt% PAA aqueous solution, 25g of 0.4wt% CNT aqueous solution, 5g of 2wt% graphene aqueous solution and 40g of pure water to the dry powder mixture, knead and stir for 30 minutes to obtain a slurry with a solid content of 65wt%.

[0155] Step 3: Add pure water to the slurry to dilute it to a solid content of 15 wt%, and then spray dry it to obtain a solid powder.

[0156] Step 4: Heat the solid powder at 100℃ for 2 hours, and then cool it to obtain premixed powder 5.

[0157] Step 5: Mix the premixed powder 5 with graphite at a mass ratio of 33.3:66.7 to obtain the negative electrode composite active material 5.

[0158] Example 6

[0159] This embodiment provides a negative electrode composite active material and its preparation method, the steps of which are as follows:

[0160] Step 1: Add 30g of silicon-based material, 70g of graphite and 1g of conductive carbon black to a mixer and mix the dry powders for 30 minutes to obtain a dry powder mixture.

[0161] Step 2: Add 10g of 10wt% PAA aqueous solution, 25g of 0.4wt% CNT aqueous solution and 50g of pure water to the dry powder mixture, knead and stir for 30 minutes to obtain a slurry with a solid content of 65wt%.

[0162] Step 3: Add pure water to the slurry to dilute it to a solid content of 15 wt%, and then spray dry it to obtain a solid powder.

[0163] Step 4: Heat the solid powder at 500℃ for 2 hours, and then cool it to obtain premixed powder 6.

[0164] Step 5: Mix the premixed powder 6 with graphite at a mass ratio of 33.3:66.7 to obtain the negative electrode composite active material 6.

[0165] Comparative Example 1

[0166] This comparative example provides a silicon-based anode material, an anode composite active material, and a method for preparing the same, with the following steps:

[0167] Step 1: Add 100g of silicon-based material, 5g of 10wt% PAA aqueous solution, and 50g of pure water to a mixer, knead and stir for 30 minutes to obtain a slurry.

[0168] Step 2: Add pure water to the slurry to dilute it to a solid content of 15 wt%, and then spray dry it to obtain a solid powder.

[0169] Step 3: Heat the solid powder at 100℃ for 2 hours, and after cooling, obtain silicon-based anode active material 7.

[0170] Step 4: Mix silicon-based anode active material 7 with graphite at a mass ratio of 10:90 to obtain anode composite active material 7.

[0171] Comparative Example 2

[0172] This comparative example provides a silicon-based anode material, an anode composite active material, and a method for preparing the same, with the following steps:

[0173] Step 1: Add 100g of silicon-based material, 1g of conductive carbon black, 25g of 0.4wt% CNT aqueous solution and 50g of pure water to a mixer, knead and stir for 30 minutes to obtain a slurry.

[0174] Step 2: Add pure water to the slurry to dilute it to a solid content of 15 wt%, and then spray dry it to obtain a solid powder.

[0175] Step 3: Heat the solid powder at 100℃ for 2 hours, and after cooling, obtain silicon-based anode active material 8.

[0176] Step 4: Mix silicon-based anode active material 8 with graphite at a mass ratio of 10:90 to obtain anode composite active material 8.

[0177] The silicon-based anode materials or anode composite active materials in the above embodiments and comparative examples were tested using the following methods:

[0178] 1) Particle size distribution tests were performed on the silicon-based anode active materials in Examples 1, 2, 3 and Comparative Examples 1, 2, and the premixed powders in Examples 4, 5, 6. The measured D10, D50, and D90 of the primary particles are shown in Table 1. The resistivity of the silicon-based anode active materials in Examples 1, 2, 3 and Comparative Examples 1, 2, and the premixed powders in Examples 4, 5, 6 was tested using the four-probe method. The measured powder resistivity is shown in Table 1.

[0179] 2) Mix the negative electrode composite active material, SP, PAA, and water of each embodiment and comparative example to form a slurry, wherein SP accounts for 1% of the mass of the negative electrode composite active material and PAA accounts for 2% of the mass of the negative electrode composite active material. Coat the slurry onto copper foil, vacuum dry and roll-press the coated electrode sheets, and assemble the rolled electrode sheets into coin cell half-cells, with lithium sheet as counter electrode. The button cell half-cells underwent rate and cycle testing: 0.1C discharge to 5mV, 0.02C discharge to 5mV, rest for 10 min, 0.1C charge to 1.5V, rest for 10 min; 1C discharge to 5mV, rest for 10 min, 0.1C charge to 1.5V, rest for 10 min; 2C discharge to 5mV, rest for 10 min, 0.1C charge to 1.5V, rest for 10 min; 0.5C discharge to 5mV, rest for 10 min, 0.5C charge to 1.5V, rest for 10 min, for a total of 50 cycles. The 1C capacity retention rate = 1C discharge capacity / 0.1C discharge capacity, and the 2C capacity retention rate = 1C discharge capacity / 0.1C discharge capacity. The measured results are shown in Table 2.

[0180] 3) Scanning electron microscopy tests were performed on the silicon-based anode active material of Example 1 and the premixed powder of Example 4. The results are shown in Figures 3 and 4. It can be seen that in the silicon-based anode active material of Example 1 and the premixed powder of Example 4, the conductive material is attached to the silicon-based particles.

[0181] 4) Before the rate and cycle tests of the coin cell, the electrode prepared by the silicon-based negative electrode active material in Example 1 was subjected to scanning electron microscopy (SEM) test. After 50 cycles, the electrode was subjected to SEM test again. The results are shown in Figures 5 and 6, respectively.

[0182] Table 1

[0183] Table 2

[0184] As can be seen from the test results above, in the silicon-based anode active material or anode composite active material of each embodiment, the conductive material can be attached to the silicon-based particles, and the adhesion is good, exhibiting better conductivity, higher rate performance, and better cycle performance.

[0185] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0186] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A silicon-based electrode active material, characterized in that, It includes silicon-based particles, an adhesive layer, and a conductive material. The conductive material has a higher conductivity than the silicon-based particles. The conductive material is attached to the silicon-based particles through the adhesive layer and can remain attached to the silicon-based particles during their expansion and contraction.

2. The silicon-based electrode active material according to claim 1, characterized in that, The adhesive layer covers the silicon-based particles, and the conductive material is independently dispersed within the adhesive layer, located on the surface of the adhesive layer, or covered by the adhesive layer.

3. The silicon-based electrode active material according to any one of claims 1 to 2, characterized in that, The conductive material accounts for 0.04% to 50% of the mass of the silicon-based electrode active material.

4. The silicon-based electrode active material according to any one of claims 1 to 2, characterized in that, The mass of the adhesive layer accounts for 0.04% to 50% of the mass of the silicon-based electrode active material.

5. The silicon-based electrode active material according to any one of claims 1 to 4, characterized in that, The conductive material includes one or more of the following: conductive carbon black, carbon nanotubes, graphene, carbon fibers, copper nanoparticles, and silver nanoparticles.

6. The silicon-based electrode active material according to any one of claims 1 to 4, characterized in that, The adhesive layer is made of one or more of the following: a polymer adhesive material, a partial carbide of the polymer adhesive material, and a complete carbide of the polymer adhesive material.

7. The silicon-based electrode active material according to claim 6, characterized in that, The structure of the polymeric adhesive material includes one or more of the following: acrylate group, carboxylic acid group, cyano group, amide group, hydroxyl group, benzene ring, carbon-carbon double bond, carbon-carbon triple bond, pyrrole, amino group and imine group.

8. The silicon-based electrode active material according to any one of claims 1 to 7, characterized in that, Includes at least one of the following features: 1) The particle size D50 of the silicon-based particles satisfies: 0.1μm≤D50≤30μm; 2) The conductive material has an irregular shape or is spherical, and the particle size D50 satisfies: 0.01μm≤D50≤10μm; 3) The conductive material is fibrous or tubular, with an average length L satisfying: 0.05μm≤D50≤100μm, and an aspect ratio L / D satisfying: 1≤L / D≤200000; 4) The conductive material is in sheet form with a thickness h satisfying: 0.1nm≤h≤10μm, and the maximum distance L1 between two points on the front side satisfies: 0.05μm≤L1≤100μm, and the maximum distance L2 between two points on the back side satisfies: 0.05μm≤L2≤100μm; 5) The conductive material is in the form of a strip, with a thickness h satisfying: 0.1nm≤h≤10μm, an average length L satisfying: 0.05μm≤L≤100μm, and an average width W satisfying: 1nm≤W≤50μm; 6) The primary particle size D10 of the silicon-based electrode active material satisfies: 0.01μm≤D10≤50μm, the particle size D50 satisfies: 0.01μm≤D50≤50μm, and the particle size D90 satisfies: 0.01μm≤D90≤50μm; 7) The resistivity of the silicon-based electrode active material is 0.5 Ω·mm to 1500 Ω·mm; 8) The silicon-based electrode active material is a silicon-based negative electrode active material.

9. The silicon-based electrode active material according to claims 1 to 8, characterized in that, The silicon-based particles comprise silicon and other elements, and satisfy at least one of the following conditions: 1) The silicon content is 5wt% to 95wt%; 2) The other elements include one or more of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, boron, copper, silver, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum and iron.

10. An electrode composite active material, characterized in that, The active material comprises a silicon-based electrode active material and active particles as described in any one of claims 1 to 9, wherein the active particles are independently and freely dispersed in the gaps between the silicon-based electrode active material, or are coated by the adhesive layer, or are connected to the silicon-based particles through the adhesive layer, or are connected to the conductive material through the adhesive layer.

11. The electrode composite active material according to claim 10, characterized in that, The adhesive layer covers the silicon-based particles and the active particles, and the conductive material is independently dispersed within the adhesive layer, located on the surface of the adhesive layer, or covered by the adhesive layer.

12. The electrode composite active material according to any one of claims 10 to 11, characterized in that, Each of the aforementioned active particles satisfies the following conditions: 1) The theoretical specific capacity of the active particles is ≥100mAh / g; 2) The conductivity of the active particles is greater than that of the silicon-based particles; 3) The expansion rate of the active particles in a certain direction under the fully lithium-intercalated state is less than the expansion rate of the silicon-based particles in that direction under the fully lithium-intercalated state.

13. The electrode composite active material according to claim 12, characterized in that, The active particles satisfy at least one of the following conditions: 1) The active particles account for 1% to 95% of the mass of the silicon-based electrode active material; 2) The active particles include one or more of the following: artificial graphite, natural graphite, hard carbon, soft carbon, carbon microspheres, lithium metal, lithium titanate, silicon-based materials, and tin-based materials; 3) The particle size D50 of the active particles satisfies: 0.1μm≤D50≤50μm.

14. A method for preparing a silicon-based electrode active material, characterized in that, Includes the following steps: Silicon-based particles and a conductive material are mixed to obtain a dry powder mixture, wherein the conductivity of the conductive material is greater than that of the silicon-based particles; The dry powder mixture, binder, and solvent are mixed to obtain a slurry with a solid content of 50 wt% to 90 wt%. After diluting the slurry, the solvent is removed, allowing the adhesive material to form an adhesive layer. This adhesive layer attaches the conductive material to the silicon-based particles and enables the conductive material to remain attached to the silicon-based particles during their expansion and contraction.

15. The method for preparing the silicon-based electrode active material according to claim 14, characterized in that, The solvent is removed by spray drying. Before spray drying, the slurry is diluted to a solid content of 1 wt% to 50 wt%.

16. The method for preparing the silicon-based electrode active material according to any one of claims 14 to 15, characterized in that, After removing the solvent, the process further includes the following step: heating the adhesive material to partially or completely carbonize it, thereby forming the adhesive layer.

17. The method for preparing the silicon-based electrode active material according to claim 16, characterized in that, The heating temperature is 60℃~700℃.

18. A method for preparing an electrode composite active material, characterized in that, The method includes the following steps: mixing silicon-based electrode active material and active particles, wherein the silicon-based electrode active material is as described in any one of claims 1 to 9, or is prepared by the preparation method described in any one of claims 10 to 17.

19. A method for preparing an electrode composite active material, characterized in that, Includes the following steps: A dry powder mixture is obtained by mixing silicon-based particles, a portion of active particles, and a conductive material, wherein the conductivity of the conductive material is greater than that of the silicon-based particles. The dry powder mixture, binder, and solvent are mixed to obtain a slurry with a solid content of 50 wt% to 90 wt%. After diluting the slurry, the solvent is removed, allowing the binder material to form a binder layer. The binder layer attaches the conductive material to the silicon-based particles, ensuring that the conductive material remains attached to the silicon-based particles during their expansion and contraction. The active particles are either coated by the binder layer or connected to the silicon-based particles through the binder layer, or connected to the conductive material through the binder layer, thus obtaining a premixed powder. Mix the premixed powder with the remaining portion of the active particles.

20. A method for preparing an electrode composite active material, characterized in that, Includes the following steps: A dry powder mixture is obtained by mixing silicon-based particles, active particles, and a conductive material, wherein the conductivity of the conductive material is greater than that of the silicon-based particles. The dry powder mixture, binder, and solvent are mixed to obtain a slurry with a solid content of 50 wt% to 90 wt%. After diluting the slurry, the solvent is removed, allowing the adhesive material to form an adhesive layer. The adhesive layer attaches the conductive material to the silicon-based particles and enables the conductive material to remain attached to the silicon-based particles during their expansion and contraction. The active particles are either coated by the adhesive layer or connected to the silicon-based particles through the adhesive layer, or connected to the conductive material through the adhesive layer.

21. An electrode sheet, characterized in that, The device includes a current collector and an electrode active layer located on the current collector. The electrode active layer includes a silicon-based electrode active material according to any one of claims 1 to 9, or an electrode composite active material according to any one of claims 10 to 13, or a silicon-based electrode active material prepared by the preparation method according to any one of claims 14 to 17, or an electrode composite active material prepared by the preparation method according to any one of claims 18 to 20.

22. The electrode sheet according to claim 21, characterized in that, The electrode active layer also includes a conductive agent and a binder.

23. A battery, characterized in that, It includes a positive electrode, a negative electrode, and a separator, wherein the separator is located between the positive electrode and the negative electrode, and the negative electrode is as described in any one of claims 21 to 22, or includes a silicon-based electrode active material as described in any one of claims 1 to 9, or includes an electrode composite active material as described in any one of claims 10 to 13, or includes a silicon-based electrode active material prepared by the preparation method as described in any one of claims 14 to 17, or includes an electrode composite active material prepared by the preparation method as described in any one of claims 18 to 20.

Images