Silicon-carbon composite material and preparation method thereof, negative pole piece, battery and electronic equipment

Abstract

The invention provides a silicon-carbon composite material and a preparation method thereof, a negative pole piece, a battery and electronic equipment. The silicon-carbon composite material provided by the embodiment of the invention comprises a plurality of silicon-based particles, the average maximum length of the projections of the plurality of silicon-based particles is Lmax, the average minimum length of the projections of the plurality of silicon-based particles is Lmin, and the average length-width ratio AR of the plurality of silicon-based particles is equal to Lmax / Lmin, so that the range of the average length-width ratio AR of the plurality of silicon-based particles is greater than or equal to 1.28 and less than or equal to 10. The silicon-carbon composite material provided by the embodiment of the invention has a relatively low expansion rate and a relatively high cycle capacity retention rate.

Description

Technical Field

[0001] The present application relates to the field of battery materials, and specifically to a silicon-carbon composite material and a preparation method thereof, a negative electrode sheet, a battery and an electronic device. Background Art

[0002] With the development of electronic devices, higher demands are being placed on the energy density of batteries in terms of longer battery life and thinner size. Traditional graphite materials have a relatively low theoretical specific capacity of 372mAh / g, and have now been developed to a value close to the theoretical value. Therefore, the continued use of traditional graphite negative electrode systems limits the further improvement of battery energy density, and there is an urgent need to develop the next generation of negative electrode materials. Silicon materials have a higher theoretical specific capacity (the theoretical specific capacity of silicon is 4200mAh / g) and are the most promising negative electrode materials for the next generation of high energy density batteries. However, silicon itself will undergo huge expansion during the lithium insertion process, causing the solid electrolyte interface (Solid Electrolyte Interphase, SEI film for short) of the negative electrode material to rupture. The SEI film needs to be repeatedly repaired during repeated discharges, which accelerates the consumption of the electrolyte, and then causes the battery's cycle capacity retention rate to drop too quickly, reducing the battery's service life. Summary of the Invention

[0003] The embodiments of the present application provide a silicon-carbon composite material having a lower expansion rate and a higher cycle capacity retention rate.

[0004] In a first aspect, an embodiment of the present application provides a silicon-carbon composite material, comprising a plurality of silicon-based particles, wherein the average maximum length of the projections of the plurality of silicon-based particles is Lmax, the average minimum length of the projections of the plurality of silicon-based particles is Lmin, and the average aspect ratio AR of the plurality of silicon-based particles is AR=Lmax / Lmin, and the range of the average aspect ratio AR of the plurality of silicon-based particles is 1.28≤AR≤10.

[0005] In a second aspect, an embodiment of the present application further provides a method for preparing a silicon-carbon composite material, which comprises:

[0006] Provide carbon source;

[0007] shaping the carbon source so as to form a precursor powder having a preset shape;

[0008] Carbonizing and activating the precursor powder to form pores to obtain a porous carbon skeleton having a plurality of pores; and

[0009] A plurality of silicon particles are deposited in the plurality of pores of the porous carbon skeleton to obtain a silicon-carbon composite material; wherein the silicon-carbon composite material includes a plurality of silicon-based particles, the silicon-based particles include a porous carbon skeleton and a plurality of silicon particles, the range of the average aspect ratio AR of the plurality of silicon-based particles is 1.28≤AR≤10, the average aspect ratio AR of the plurality of silicon-based particles is AR=Lmax / Lmin, the average maximum length of the projections of the plurality of silicon-based particles is Lmax, and the average minimum length of the projections of the plurality of silicon-based particles is Lmin.

[0010] In a third aspect, an embodiment of the present application further provides a negative electrode plate, the negative electrode plate comprising:

[0011] a negative electrode current collector; and

[0012] A negative electrode active layer, wherein the negative electrode active layer comprises the silicon-carbon composite material according to the first or second embodiment of the present application.

[0013] In a fourth aspect, an embodiment of the present application further provides a battery, comprising:

[0014] electrolyte;

[0015] a positive electrode sheet, wherein the positive electrode sheet is at least partially immersed in the electrolyte;

[0016] a diaphragm, the diaphragm being located on one side of the positive electrode plate and at least partially immersed in the electrolyte, and

[0017] The negative electrode plate described in the embodiment of the third aspect of the present application is arranged on the side of the diaphragm away from the positive electrode plate and is at least partially immersed in the electrolyte.

[0018] In a fifth aspect, an embodiment of the present application further provides an electronic device, comprising:

[0019] the device itself; and

[0020] The battery described in the fourth embodiment of the present application is used to power the device body.

[0021] The silicon-carbon composite material of the present application designs the average aspect ratio of a plurality of silicon-based particles so that the average aspect ratio AR of the plurality of silicon-based particles is in the range of 1.28≤AR≤10. This results in a shorter ion transmission path from the surface to the center of the silicon-based particles, thereby improving the dynamic performance of the battery using the silicon-carbon composite material; in addition, there are more contact points between adjacent silicon-based particles, and the conductive connection between adjacent silicon-based particles is better, thereby improving the conductivity of the silicon-carbon composite material and improving the rate performance and cycle performance of the battery; furthermore, the silicon-based particles of the silicon-carbon composite material have a larger aspect ratio AR, so that when the silicon-based particles are rolled on the negative electrode sheet, the long axis direction of the silicon-based particles (i.e., the maximum length direction of the projection) tends to be parallel to the extension direction of the negative electrode collector of the negative electrode sheet, and the short axis direction of the silicon-based particles (i.e., the minimum length direction of the projection) tends to be perpendicular to the extension direction of the negative electrode collector (i.e., parallel to the thickness direction of the negative electrode sheet, also known as the Z-axis direction), thereby reducing the expansion rate of the negative electrode sheet along the thickness direction during the process of metal ion insertion (e.g., lithium insertion) of the negative electrode sheet, reducing the probability of silicon-based particle damage, and thereby improving the cycle capacity retention rate of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 Schematic diagram of the structure of silicon-based particles according to an embodiment of the present application.

[0024] Figure 2 This is a schematic structural diagram of silicon-based particles according to another embodiment of the present application.

[0025] Figure 3 This is a schematic structural diagram of silicon-based particles according to another embodiment of the present application.

[0026] Figure 4 Schematic diagram of a process for preparing a silicon-carbon composite material according to an embodiment of the present application.

[0027] Figure 5 It is a schematic flow chart of a method for preparing a silicon-carbon composite material according to another embodiment of the present application.

[0028] Figure 6 Schematic diagram of the carbonization and pore-forming process in the method for preparing a silicon-carbon composite material according to an embodiment of the present application.

[0029] Figure 71 is a flow chart of a method for preparing a silicon-carbon composite material according to another embodiment of the present application.

[0030] Figure 8 Schematic diagram of the structure of the negative electrode sheet of one embodiment of the present application.

[0031] Figure 9 Schematic diagram of the structure of a battery according to an embodiment of the present application.

[0032] Figure 10 The battery of one embodiment of the present application is Figure 9 Schematic diagram of the cross-sectional structure in the AA direction.

[0033] Figure 11 It is a structural schematic diagram of the positive electrode plate of an embodiment of the present application.

[0034] Figure 12 It is a structural diagram of an electronic device according to an embodiment of the present application.

[0035] Figure 13 It is a schematic diagram of the exploded structure of an electronic device according to an embodiment of the present application.

[0036] Figure 14 This is a circuit block diagram of an electronic device according to an embodiment of the present application.

[0037] Description of reference numerals:

[0038] 100-silicon-based particles, 10-porous carbon skeleton, 11-pores, 20-silicon particles, 30-carbon coating layer, 400-negative electrode plate, 410-negative current collector, 420-negative active layer, 500-battery, 510-positive electrode plate, 511-positive current collector, 512-positive active layer, 520-diaphragm, 540-housing, 541-receiving cavity, 600-electronic device, 610-device body, 611-display, 613-middle frame, 615-housing, 616-processor, 617-memory, 618-camera module. DETAILED DESCRIPTION

[0039] In order to enable those skilled in the art to better understand the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0040] The terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish between different objects, not to describe a particular order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0041] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0042] It should be noted that, for the convenience of explanation, in the embodiments of the present application, the same reference numerals represent the same components, and for the sake of brevity, detailed descriptions of the same components are omitted in different embodiments.

[0043] With the development of electronic devices, there is a growing demand for higher battery energy density, both for longer battery life and thinner dimensions. Traditional graphite materials have a relatively low theoretical specific capacity of 372 mAh / g, and development has already reached close to this theoretical value. Therefore, continued use of traditional graphite anode systems limits further improvements in battery energy density, necessitating the development of next-generation anode materials.

[0044] Silicon has a high theoretical specific capacity (4200 mAh / g) and is the most promising anode material for next-generation, high-energy-density batteries. However, silicon itself expands significantly during lithium insertion, causing the solid electrolyte interphase (SEI) membrane in the anode material to rupture. Repeated discharge requires repeated repair of the SEI membrane, which accelerates electrolyte consumption, leading to a rapid decrease in the battery's cycle capacity retention rate and shortening the battery's service life.

[0045] See Figure 1 An embodiment of the present application provides a silicon-carbon composite material, which includes a plurality of silicon-based particles 100, wherein the average maximum length of the projections of the plurality of silicon-based particles 100 is Lmax, the average minimum length of the projections of the plurality of silicon-based particles 100 is Lmin, and the average aspect ratio AR of the plurality of silicon-based particles 100 is AR=Lmax / Lmin, then the range of the average aspect ratio AR of the plurality of silicon-based particles 100 is 1.28≤AR≤10.

[0046] The silicon-carbon composite material of the present application can be used as the negative electrode active material for the negative electrode active layer of the negative electrode sheet of a battery. Optionally, the battery can be, but is not limited to, a lithium battery. Optionally, the lithium battery can be, but is not limited to, at least one of a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, and the like.

[0047] It can be understood that the average aspect ratio AR of the silicon-carbon composite material is in the range of 1.28≤AR≤10.

[0048] It is understood that the average maximum length of the projections of the plurality of silicon-based particles 100 refers to the average of the maximum lengths of the projections of the plurality of silicon-based particles 100. The average minimum length of the projections of the plurality of silicon-based particles 100 refers to the average of the minimum lengths of the projections of the plurality of silicon-based particles 100. The average aspect ratio AR of the plurality of silicon-based particles 100 refers to the average of the aspect ratios AR of the plurality of silicon-based particles 100.

[0049] It should be noted that the maximum length of the projection of the silicon-based particle 100 can be the Feret Maximum Diameter, and the minimum length of the projection of the silicon-based particle 100 can be the Feret Minimum Diameter. The term "Feret Maximum Diameter" is a metric that describes the longest possible distance of a particle or object in a two-dimensional projection, defined as the maximum distance between parallel tangents in any direction. Simply put, it is the maximum projected length of an object after all possible angles of rotation. The "Feret Minimum Diameter" is the minimum projected length in all directions.

[0050] It should be noted that "a plurality" refers to greater than or equal to two. For example, it can be, but is not limited to, 2, 5, 10, 20, 30, 50, 100, 300, 500, 800, 1000, 1500, 3000, 5000, 10000, etc. The silicon-carbon composite material contains a large number of silicon-based particles 100, the specific number of which is related to the quality of the silicon-carbon composite material.

[0051] For example, if 5 grams of the silicon-carbon composite material is weighed, the average aspect ratio AR of the plurality of silicon-based particles 100 is the average of the aspect ratios of all the silicon-based particles 100 contained in the 5 grams of the silicon-carbon composite material.

[0052] As another example, when the silicon-carbon composite material is applied to the negative electrode active layer, the average aspect ratio AR of the plurality of silicon-based particles 100 is the average of the aspect ratios of all the silicon-based particles 100 on the negative electrode active layer.

[0053] Specifically, the average aspect ratio AR of the plurality of silicon-based particles 100 may be, but is not limited to, 1.28, 1.3, 1.5, 1.8, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, etc. If the average aspect ratio AR of the multiple silicon-based particles 100 is too small, the ion transmission path from the surface of the silicon-based particle 100 to the center of the silicon-based particle 100 becomes longer, thereby reducing the dynamic performance of the battery using the silicon-carbon composite material; in addition, if the average aspect ratio AR of the multiple silicon-based particles 100 is too small, there are too few contact points between adjacent silicon-based particles 100, and the conductive connection between adjacent silicon-based particles 100 is reduced, thereby reducing the conductivity of the silicon-carbon composite material, increasing the impedance of the negative electrode sheet using the silicon-carbon composite material, and reducing the rate performance and cycle performance of the battery; furthermore, if the average aspect ratio AR of the multiple silicon-based particles 100 is too small, the orientation angle of the silicon-based particles 100 in the negative electrode sheet using the silicon-carbon composite material will increase the expansion rate of the silicon-carbon composite material after the insertion of metal ions (such as lithium). If the average aspect ratio AR of the multiple silicon-based particles 100 is too large, the compressive resistance of the silicon-based particles 100 is reduced, so that when the negative electrode sheet is rolled during the process of making the silicon-carbon composite material into a negative electrode sheet, the silicon-based particles 100 are easily crushed; or the silicon-based particles 100 are easily broken during the battery cycle, and the electrolyte needs to be continuously consumed to repair the SEI film of the negative electrode sheet, which reduces the cycle performance of the battery.

[0054] Furthermore, in some embodiments, the average aspect ratio AR of the plurality of silicon-based particles 100 is in the range of 2≤AR≤5. This allows the silicon-based particles 100 to have a shorter ion transmission path from the surface to the center, thereby improving the dynamic performance of the battery using the silicon-carbon composite material; in addition, there are more contact points between adjacent silicon-based particles 100, and the conductive connection between adjacent silicon-based particles 100 is better, thereby improving the conductivity of the silicon-carbon composite material and improving the rate performance and cycle performance of the battery; furthermore, the silicon-based particles 100 of the silicon-carbon composite material have a larger aspect ratio AR, so that when the silicon-based particles 100 are rolled on the negative electrode sheet, the silicon-based particles The long axis direction of 100 (i.e., the maximum length direction of the projection) tends to be parallel to the extension direction of the negative electrode current collector of the negative electrode plate, and the short axis direction of the silicon-based particle 100 (i.e., the minimum length direction of the projection) tends to be perpendicular to the extension direction of the negative electrode current collector (i.e., parallel to the thickness direction of the negative electrode plate, also known as the Z-axis direction), thereby reducing the expansion rate of the negative electrode plate along the thickness direction during the process of metal ion insertion (such as lithium insertion), reducing the probability of damage to the silicon-based particle 100, and thus improving the cycle capacity retention rate of the battery.

[0055] The silicon-carbon composite material of the present application is designed to have an average aspect ratio of multiple silicon-based particles 100, so that the average aspect ratio AR of the multiple silicon-based particles 100 is in the range of 1.28≤AR≤10. This makes the silicon-based particles 100 have a shorter ion transmission path from the surface to the center, improving the dynamic performance of the battery using the silicon-carbon composite material; in addition, there are more contact points between adjacent silicon-based particles 100, and the conductive connection between adjacent silicon-based particles 100 is better, which improves the conductivity of the silicon-carbon composite material and improves the rate performance and cycle performance of the battery; furthermore, the silicon-based particles 100 of the silicon-carbon composite material have a larger aspect ratio AR, so that when the silicon-based particles 100 are rolled on the negative electrode sheet, the silicon-based particles 100 are The long axis direction of 00 (i.e. the maximum length direction of the projection) tends to be parallel to the extension direction of the negative electrode current collector of the negative electrode plate, and the short axis direction of the silicon-based particle 100 (i.e. the minimum length direction of the projection) tends to be perpendicular to the extension direction of the negative electrode current collector (i.e. parallel to the thickness direction of the negative electrode plate, also called the Z-axis direction), thereby reducing the expansion rate of the negative electrode plate along the thickness direction during the process of metal ion insertion (such as lithium insertion), reducing the probability of damage to the silicon-based particle 100, and thus improving the cycle capacity retention rate of the battery.

[0056] In some embodiments, the curvature of any point on the surface of the silicon-based particle 100 is H, and the average area ratio of the curvature H≧0 on the surfaces of the plurality of silicon-based particles 100 is greater than or equal to 70%.

[0057] It should be noted that the proportion of the area on the surface of the silicon-based particle 100 with a curvature greater than or equal to 0 refers to the ratio of the sum of the areas of all points on the surface of the silicon-based particle 100 with a curvature H≥0 to the surface area of ​​the silicon-based particle 100.

[0058] For example, the silicon-carbon composite material includes four silicon-based particles 100, and the area ratios of the surface curvature H ≥ 0 of the four silicon-based particles 100 are 80%, 65%, 90%, and 75%, respectively. Then, the average area ratio of the surface curvature H ≥ 0 of the four silicon-based particles 100 is 77.5%. It should be noted that the silicon-carbon composite material contains a large number of silicon-based particles 100. The example here is only for better illustrating how to calculate the average area ratio and should not be construed as limiting the silicon-carbon composite material and silicon-based particles 100 of the embodiments of the present application.

[0059] Specifically, the average value of the area ratio of the curvature H≥0 on the surface of the multiple silicon-based particles 100 can be but not limited to 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, 90%, 92%, 94%, 96%, 98%, etc.

[0060] In this embodiment, if the average of the area ratios of curvature H ≥ 0 on the surfaces of the plurality of silicon-based particles 100 is too small, the surfaces of the silicon-based particles 100 have more concave structures. During the rolling and lithium insertion and delithiation processes of the silicon-carbon composite material, the silicon-based particles 100 are susceptible to locally concentrated stress, which can easily lead to cracking and pulverization. This increases the side reactions and electrolyte consumption of the battery using the silicon-carbon composite material, and reduces the cycle performance of the battery. In this embodiment, the average of the area ratios of curvature H ≥ 0 on the surfaces of the plurality of silicon-based particles 100 of the silicon-carbon composite material is greater than or equal to 70%, indicating that the surfaces of the silicon-based particles 100 have more convex structures. The convex structures of the silicon-based particles 100 can effectively disperse the stress of the silicon-based particles 100 during the rolling and lithium insertion and delithiation processes through the geometric curvature effect, thereby improving the compressive resistance and integrity of the silicon-based particles 100, and inhibiting crack propagation and pulverization of the silicon-based particles 100, so that the battery using the silicon-carbon composite material has better cycle performance and higher cycle capacity retention.

[0061] In some embodiments, an average maximum length Lmax of the projected silicon-based particles 100 is in a range of 1 μm≤Lmax≤20 μm.

[0062] Specifically, the average maximum length Lmax of the projections of the plurality of silicon-based particles 100 can be, but is not limited to, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, etc.

[0063] In this embodiment, if the average maximum length Lmax of the projections of the plurality of silicon-based particles 100 is too small, the specific surface area of ​​the silicon-carbon composite material is too high, which increases the side reactions of the battery using the silicon-carbon composite material during the charge and discharge cycle, reduces the cycle performance of the battery, and reduces the cycle capacity retention rate and cycle life of the battery. If the average maximum length Lmax of the projections of the plurality of silicon-based particles 100 is too large, the size of the entire silicon-based particle 100 is large, and the transmission path of the metal ions during the charge and discharge process of the battery is too long, which reduces the dynamic performance and rate performance of the battery. In addition, if the average maximum length Lmax of the projections of the plurality of silicon-based particles 100 is too large, the average aspect ratio AR of the plurality of silicon-based particles 100 is too large, which reduces the compressive strength of the silicon-based particles 100. When the negative electrode sheet is rolled during the process of making the silicon-carbon composite material into a negative electrode sheet, the silicon-based particles 100 are easily crushed; or the silicon-based particles 100 are easily broken during the battery cycle, requiring continuous consumption of electrolyte to repair the SEI film of the negative electrode sheet, which reduces the cycle performance of the battery.

[0064] In some embodiments, an average minimum length Lmin of the projections of the plurality of silicon-based particles 100 is in the range of 0.1 μm≤Lmin≤10 μm.

[0065] Specifically, the average minimum length Lmin of the projections of the plurality of silicon-based particles 100 may be, but is not limited to, 0.1 μm, 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, etc.

[0066] In this embodiment, if the average minimum length Lmin of the projections of the multiple silicon-based particles 100 is too small, the average aspect ratio AR of the multiple silicon-based particles 100 is too large, which reduces the compressive resistance of the silicon-based particles 100, making it easy for the silicon-based particles 100 to be crushed when the negative electrode sheet is rolled during the process of making the silicon-carbon composite material into the negative electrode sheet; or the silicon-based particles 100 are easily broken during the battery cycle, requiring continuous consumption of electrolyte to repair the SEI film of the negative electrode sheet, thereby reducing the cycle performance of the battery. If the average minimum length Lmin of the projections of the multiple silicon-based particles 100 is too large, the average aspect ratio AR of the multiple silicon-based particles 100 is too small, and the ion transmission path from the surface of the silicon-based particle 100 to the center of the silicon-based particle 100 becomes longer, thereby reducing the dynamic performance of the battery using the silicon-carbon composite material; in addition, there are too few contact points between adjacent silicon-based particles 100, and the conductive connection between adjacent silicon-based particles 100 is reduced, which reduces the conductivity of the silicon-carbon composite material, increases the impedance of the negative electrode sheet using the silicon-carbon composite material, and reduces the rate performance and cycle performance of the battery; furthermore, the orientation angle of the silicon-based particles 100 in the negative electrode sheet using the silicon-carbon composite material will increase the expansion rate of the silicon-carbon composite material after the insertion of metal ions (such as lithium).

[0067] See Figure 2 In some embodiments, the silicon-based particles 100 include a porous carbon skeleton 10 and a plurality of silicon particles 20 , wherein the porous carbon skeleton 10 has a plurality of pores 11 ; the plurality of silicon particles 20 are distributed in the plurality of pores 11 of the porous carbon skeleton 10 .

[0068] It should be noted that the silicon particles 20 do not fill the entire pores 11 , that is, after the silicon particles 20 are deposited in the pores 11 , part of the pores 11 remain, thereby better buffering the expansion of the silicon particles 20 during the lithium insertion process.

[0069] In this embodiment, the silicon-based particles 100 include a porous carbon skeleton 10 and a plurality of silicon particles 20, and the plurality of silicon particles 20 are distributed in the plurality of pores 11 of the porous carbon skeleton 10. During the lithium insertion process of the silicon-based particles 100, the porous carbon skeleton 10 can buffer the expansion of the silicon particles 20 during the lithium insertion process, and confine the silicon particles 20 in the porous carbon skeleton 10, so that the silicon-based particles 100 are not easily broken during the lithium insertion process. When applied to batteries, it can reduce the expansion rate of the negative electrode of the battery, reduce the side reactions of the battery, and thus increase the cycle capacity retention rate of the battery.

[0070] In some embodiments, the mass fraction of the silicon particles 20 in the silicon-based particles 100 ranges from 5% to 95%.

[0071] In the embodiments of the present application, when a numerical value range from a to b is involved, unless otherwise specified, it means that the numerical value can be any numerical value between a and b, including the endpoint numerical value a and the endpoint numerical value b.

[0072] In other words, the mass fraction of silicon in the silicon-based particles 100 ranges from 5% to 95%.

[0073] Specifically, the mass fraction of the silicon particles 20 in the silicon-based particles 100 can be, but is not limited to, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, etc.

[0074] In this embodiment, if the mass fraction of the silicon particles 20 in the silicon-based particles 100 is too low, the pores 11 of the porous carbon skeleton 10 remain relatively large (i.e., more pores 11 are not filled with silicon particles 20, or even if there are silicon particles 20, the space occupied by the silicon particles 20 is too small), which increases the side reactions of the battery using the silicon-carbon composite material at high temperatures (such as 45°C, 60°C, etc.), deteriorates the high-temperature cycle performance of the battery, and reduces the gram capacity of the silicon-carbon composite material. If the mass fraction of the silicon particles 20 in the silicon-based particles 100 is too high, the carbon content of the silicon-based particles 100 is too low, that is, the proportion of the porous carbon skeleton 10 is too small, then in the process of lithium insertion of the silicon particles 20, the expansion rate of the silicon particles 20 is too high, and the porous carbon skeleton 10 does not have enough space to buffer the expansion of the silicon particles 20, thereby making the silicon-based particles 100 easy to break, increasing the expansion rate of the battery, and reducing the cycle capacity retention rate of the battery.

[0075] It should be noted that the main components of the silicon-based particles 100 are carbon and silicon (silicon particles 20 ). In addition, the silicon-based particles 100 also contain a small amount of oxygen and other impurity elements (such as phosphorus, sulfur, metals, etc.).

[0076] In some embodiments, the average size of the silicon particles 20 (ie, the average particle diameter of the silicon particles 20 ) ranges from 0.2 nm to 20 nm.

[0077] Specifically, the average size of the silicon particles 20 may be, but is not limited to, 0.2 nm, 0.4 nm, 0.6 nm, 0.8 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, etc.

[0078] In this embodiment, if the size of the silicon particles 20 is too small, a silicon phase cannot be formed (smaller than the size of a single silicon atom). If the size of the silicon particles 20 is too large, the silicon particles 20 are prone to rupture during the lithium insertion and delithiation process, resulting in excessive volume deformation, which is difficult to be buffered by the surrounding pores 11, thereby increasing the expansion rate of the silicon-based particles 100 and reducing the cycle performance of the battery using the silicon-carbon composite material.

[0079] Furthermore, in some embodiments, the average size of the silicon particles 20 ranges from 0.2 nm to 10 nm. This allows for better formation of the silicon phase and minimizes deformation of the silicon particles 20 during lithium insertion and extraction. The silicon particles 20 are better buffered by the surrounding porous carbon skeleton 10, making them less susceptible to rupture. This reduces the expansion rate of the silicon-based particles 100, resulting in higher cycle performance for batteries using the silicon-carbon composite material.

[0080] Furthermore, in some embodiments, the average size of the silicon particles 20 ranges from 0.2 nm to 7 nm. This allows for better formation of the silicon phase and minimizes deformation of the silicon particles 20 during lithium insertion and extraction. The silicon particles 20 are better buffered by the surrounding porous carbon skeleton 10, making them less susceptible to rupture. This reduces the expansion rate of the silicon-based particles 100, resulting in higher cycle performance for batteries using the silicon-carbon composite material.

[0081] Furthermore, the average size of the silicon particles 20 ranges from 0.2 nm to 3 nm. This allows for better formation of the silicon phase and minimizes deformation of the silicon particles 20 during lithium insertion and extraction. The silicon particles 20 are better buffered by the surrounding porous carbon skeleton 10, making them less susceptible to rupture. This reduces the expansion rate of the silicon-based particles 100, resulting in higher cycle performance for batteries using the silicon-carbon composite material.

[0082] In some embodiments, the porosity 11 of the porous carbon skeleton 10 ranges from 20% to 99%.

[0083] Specifically, the porosity 11 of the porous carbon skeleton 10 can be but is not limited to 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, etc.

[0084] In this embodiment, if the porosity 11 of the porous carbon skeleton 10 is too low, the proportion of silicon particles 20 in the silicon-based particles 100 is too low, thereby reducing the gram capacity of the silicon-based particles 100. If the porosity 11 of the porous carbon skeleton 10 is too high, the mechanical strength of the porous carbon skeleton 10 is reduced, and the compressive strength of the silicon-based particles 100 is reduced. The expansion force exerted on the porous carbon skeleton 10 by the silicon particles 20 during the lithium insertion process can easily cause the porous carbon skeleton 10 to pulverize or break, thereby reducing the cycle performance of the silicon-based particles 100. In addition, if the porosity 11 of the porous carbon skeleton 10 is too high, the surface of the silicon-based particles 100 has more open pores, and the electrolyte can easily enter the open pores, thereby increasing the side reactions of the silicon-carbon composite material and reducing the cycle performance of the battery.

[0085] Furthermore, the porosity 11 of the porous carbon skeleton 10 is in the range of 40% to 80%. This allows the silicon-based particles 100 to have a higher gram capacity, and the porous carbon skeleton 10 has higher mechanical strength, which can better resist and buffer the expansion force generated by the expansion of the silicon particles 20 during the lithium insertion process, making the silicon-based particles 100 less likely to pulverize or break, thereby improving the cycle performance of the battery using the silicon-carbon composite material.

[0086] In some embodiments, the average pore diameter of the pores 11 ranges from 0.4 nm to 20 nm.

[0087] Specifically, the average pore diameter of the pores 11 can be, but is not limited to, 0.4 nm, 0.6 nm, 0.8 nm, 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, etc.

[0088] In this embodiment, if the average pore size of the pores 11 is too small, it will be difficult for silane molecules to enter the pores 11 and deposit during the preparation of the silicon-based particles 100, thereby reducing the proportion of silicon particles 20 in the silicon-based particles 100 and the gram capacity of the silicon-based particles 100. If the average pore size of the pores 11 is too large, the size of the silicon particles 20 within the pores 11 will be too large, thereby reducing the inhibitory effect of the through-porous carbon skeleton on the expansion of the silicon particles 20 during lithium insertion. In addition, the larger silicon particles 20 are prone to rupture during the lithium insertion process, thereby deteriorating the cycling performance of the battery.

[0089] Furthermore, in some embodiments, the average pore size of the pores 11 ranges from 0.6 nm to 10 nm. This facilitates the deposition of silane molecules into the pores 11 of the porous carbon framework 10, resulting in a higher proportion of silicon particles 20 in the silicon-based particles 100 and a higher gram capacity. It also prevents the silicon particles 20 from being too large, improving the porous carbon framework 10's ability to suppress the expansion of the silicon particles 20 during lithium insertion, and thus improving the battery's cycling performance.

[0090] Furthermore, in some embodiments, the average pore size of the pores 11 ranges from 0.6 nm to 5 nm. This facilitates the deposition of silane molecules into the pores 11 of the porous carbon framework 10, resulting in a higher proportion of silicon particles 20 in the silicon-based particles 100 and a higher gram capacity. It also prevents the silicon particles 20 from becoming too large, enhancing the porous carbon framework 10's ability to suppress the expansion of the silicon particles 20 during lithium insertion, and improving the battery's cycling performance.

[0091] In some embodiments, the pore volume of the porous carbon skeleton 10 is in the range of 0.1 cm 3 / g to 5.5cm 3 / g.

[0092] Specifically, the pore volume of the porous carbon skeleton 10 may be, but is not limited to, 0.1 cm 3 / g, 0.3cm 3 / g, 0.5cm 3 / g, 0.8cm 3 / g, 1.0cm 3 / g, 1.3cm 3 / g, 1.5cm 3 / g, 1.8cm 3 / g, 2.0cm 3 / g, 2.3cm 3 / g, 2.5cm 3 / g, 2.8cm 3 / g, 3.0cm 3 / g, 3.3cm 3 / g, 3.5cm 3 / g, 3.8cm 3 / g, 4.0cm 3 / g, 4.3cm 3 / g, 4.5cm 3 / g, 4.8cm 3 / g, 5.0cm 3 / g, 5.3cm 3 / g, 5.5cm 3 / g, etc.

[0093] In this embodiment, if the pore volume of the porous carbon skeleton 10 is too small, the proportion of silicon particles 20 that can be deposited in the silicon-based particles 100 is reduced, and the gram capacity of the silicon-based particles 100 is reduced. If the pore volume of the porous carbon skeleton 10 is too large, the mechanical strength of the porous carbon skeleton 10 is reduced, the compressive strength of the silicon-based particles 100 is reduced, and the expansion force exerted on the porous carbon skeleton 10 by the silicon particles 20 during the lithium insertion process is easily caused to pulverize or break the porous carbon skeleton 10, thereby reducing the cycle performance of the silicon-based particles 100. In addition, if the porosity 11 of the porous carbon skeleton 10 is too high, the surface of the silicon-based particles 100 has more open pores, and the electrolyte easily enters the open pores, which increases the side reactions of the silicon-carbon composite material and reduces the cycle performance of the battery.

[0094] Furthermore, in some embodiments, the pore volume of the porous carbon skeleton 10 is in the range of 0.5 cm 3 / g to 4cm 3 This allows the silicon-based particles 100 to have a higher gram capacity, and the porous carbon skeleton 10 to have higher mechanical strength, which can better resist and buffer the expansion force generated by the silicon particles 20 during lithium insertion, making the silicon-based particles 100 less likely to pulverize or break, thereby improving the cycle performance of batteries using the silicon-carbon composite material.

[0095] Furthermore, in some embodiments, the pore volume of the porous carbon skeleton 10 is in the range of 0.5 cm 3 / g to 2cm 3 This allows the silicon-based particles 100 to have a higher gram capacity, and the porous carbon skeleton 10 to have higher mechanical strength, which can better resist and buffer the expansion force generated by the silicon particles 20 during lithium insertion, making the silicon-based particles 100 less likely to pulverize or break, thereby improving the cycle performance of batteries using the silicon-carbon composite material.

[0096] See Figure 3 In some embodiments, the silicon-based particle 100 further includes a carbon coating layer 30 , and the carbon coating layer 30 is wrapped around the surface of the porous carbon skeleton 10 .

[0097] Optionally, the carbon coating layer 30 closes the plurality of pores 11 of the porous carbon skeleton 10 .

[0098] It can be understood that the carbon coating layer 30 is used to wrap the porous carbon skeleton 10 and wrap the silicon particles 20 in the multiple pores 11 of the porous carbon skeleton 10 to minimize the direct exposure of the silicon particles 20 to the silicon-based particles 100. When the silicon particles 20 are exposed to the surface, the silicon particles 20 are in direct contact with the electrolyte, side reactions will occur, and the active silicon particles 20 will be consumed, thereby reducing the specific capacity of the silicon-based particles 100 and causing the cycle capacity retention rate of the silicon-based particles 100 to continue to decrease with the increase in the number of cycles. In this embodiment, the silicon-based particles 100 have a carbon coating layer 30. When applied to a battery, it can prevent the silicon particles 20 from directly contacting the electrolyte, thereby avoiding more side reactions, so that the silicon-based particles 100 have a higher cycle capacity retention rate, especially high-temperature cycle performance. In addition, the carbon coating layer 30 also provides an increase in the electronic conductivity of the silicon-based particles 100 and improves the kinetic performance of the silicon-based particles 100.

[0099] Optionally, the carbon coating layer 30 has a thickness ranging from 1 nm to 1 μm (1000 nm).

[0100] Specifically, the thickness of the carbon coating layer 30 may be, but is not limited to, 1 nm, 5 nm, 10 nm, 20 nm, 30 nm, 50 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, etc.

[0101] In this embodiment, if the thickness of the carbon coating layer 30 is too thin, the effect of the carbon coating layer 30 on reducing the side reaction between the silicon particles 20 and the electrolyte and improving the electronic conductivity of the silicon-based particles 100 is not obvious; if the thickness of the carbon coating layer 30 is too thick, the impedance of lithium ion diffusion is increased, which will also reduce the kinetic performance of the battery. In addition, the amount of active material in the silicon-based particles 100 is reduced, thereby reducing the gram capacity of the silicon-based particles 100.

[0102] In some embodiments, the specific surface area S of the silicon-based particles 100 is in the range of 0.5 m2 / g≤S≤30 m2 / g.

[0103] Specifically, the specific surface area S of the silicon-based particles 100 can be, but is not limited to, 0.5 m2 / g, 0.8 m2 / g, 1 m2 / g, 2 m2 / g, 4 m2 / g, 6 m2 / g, 8 m2 / g, 12 m2 / g, 14 m2 / g, 16 m2 / g, 18 m2 / g, 22 m2 / g, 24 m2 / g, 26 m2 / g, 28 m2 / g, 30 m2 / g, etc.

[0104] In this embodiment, if the specific surface area S of the silicon-based particles 100 is too low, the area for metal ion embedding during the battery's charge and discharge process is too small, resulting in increased polarization of the negative electrode plate, prone to lithium deposition, and reduced battery dynamic performance. If the specific surface area S of the silicon-based particles 100 is too high, the battery using the silicon-carbon composite material increases side reactions during the charge and discharge cycle, reducing the battery's cycle performance, cycle capacity retention rate, and cycle life.

[0105] Furthermore, in some embodiments, the specific surface area S of the silicon-based particles 100 is in the range of 1 m2 / g≤S≤25 m2 / g. This allows the silicon-based particles 100 to have higher dynamic performance and higher cycle capacity retention.

[0106] In some embodiments, the shape of the silicon-based particles 100 includes at least one of an oblate spheroid, an ellipsoid, a plate, a sheet, a cuboid, a rod, a column, a needle, and a fiber. The use of silicon-based particles 100 of these shapes can reduce the difficulty of preparing the silicon-based particles 100 and simplify the preparation process of the silicon-based particles 100. In addition, the average aspect ratio of the silicon-based particles 100 can be better made to be in the range of 1.28≤AR≤10, thereby better improving the dynamic performance and cycle capacity retention rate of the battery using the silicon-carbon composite material of this embodiment. Furthermore, the silicon-based particles 100 of these shapes are more conducive to buffering the stress generated during the lithium insertion process of the silicon-based particles 100, that is, the silicon-based particles 100 of these shapes have a stress buffering effect.

[0107] The silicon-carbon composite materials of the embodiments of the present application can be prepared by the methods described in the following embodiments of the present application. In addition, they can also be prepared by other methods. The preparation methods of the embodiments of the present application are merely one or more preparation methods of the silicon-carbon composite materials of the present application and should not be understood as limiting the silicon-carbon composite materials provided in the embodiments of the present application.

[0108] See Figure 4 , the present application embodiment provides a method for preparing a silicon-carbon composite material, which comprises:

[0109] S201, providing a carbon source;

[0110] S202, shaping the carbon source to form a precursor powder having a preset shape;

[0111] Optionally, the preset shape may include, but is not limited to, at least one of an oblate spheroid, an ellipsoid, a plate, a sheet, a cuboid, a rod, a column, a needle, and a fiber. Using precursor powders with these preset shapes can reduce the difficulty of preparing the precursor powders of the preset shapes and simplify the preparation process of the silicon-based particles 100. Furthermore, the average aspect ratio of the prepared silicon-based particles 100 can be optimized to be within the range of 1.28 ≤ AR ≤ 10, thereby further improving the dynamic performance and cycle capacity retention of batteries using the silicon-carbon composite material of this embodiment.

[0112] S203, carbonizing and activating the precursor powder to form pores to obtain a porous carbon skeleton 10, wherein the porous carbon skeleton 10 has a plurality of pores 11; and

[0113] S204, depositing a plurality of silicon particles 20 in the plurality of pores 11 of the porous carbon skeleton 10 to obtain a silicon-carbon composite material; wherein the silicon-carbon composite material includes a plurality of silicon-based particles 100, the silicon-based particles 100 include a porous carbon skeleton 10 and a plurality of silicon particles 20, the range of the average aspect ratio AR of the plurality of silicon-based particles 100 is 1.28≤AR≤10, the average aspect ratio AR of the plurality of silicon-based particles 100 is AR=Lmax / Lmin, the average maximum length of the projections of the plurality of silicon-based particles 100 is Lmax, and the average minimum length of the projections of the plurality of silicon-based particles 100 is Lmin.

[0114] Specifically, the average aspect ratio AR of the plurality of silicon-based particles 100 may be, but is not limited to, 1.28, 1.3, 1.5, 1.8, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, 9.0, 9.5, 10, etc. If the average aspect ratio AR of the multiple silicon-based particles 100 is too small, the ion transmission path from the surface of the silicon-based particle 100 to the center of the silicon-based particle 100 becomes longer, thereby reducing the dynamic performance of the battery using the silicon-carbon composite material; in addition, if the average aspect ratio AR of the multiple silicon-based particles 100 is too small, there are too few contact points between adjacent silicon-based particles 100, and the conductive connection between adjacent silicon-based particles 100 is reduced, thereby reducing the conductivity of the silicon-carbon composite material, increasing the impedance of the negative electrode sheet using the silicon-carbon composite material, and reducing the rate performance and cycle performance of the battery; furthermore, if the average aspect ratio AR of the multiple silicon-based particles 100 is too small, the orientation angle of the silicon-based particles 100 in the negative electrode sheet using the silicon-carbon composite material will increase the expansion rate of the silicon-carbon composite material after the insertion of metal ions (such as lithium). If the average aspect ratio AR of the multiple silicon-based particles 100 is too large, the compressive resistance of the silicon-based particles 100 is reduced, so that when the negative electrode sheet is rolled during the process of making the silicon-carbon composite material into a negative electrode sheet, the silicon-based particles 100 are easily crushed; or the silicon-based particles 100 are easily broken during the battery cycle, and the electrolyte needs to be continuously consumed to repair the SEI film of the negative electrode sheet, which reduces the cycle performance of the battery.

[0115] For detailed descriptions of other aspects of the silicon-carbon composite material, silicon-based particles 100, porous carbon skeleton 10, pores 11, silicon particles 20, etc., please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0116] The preparation method of the silicon-carbon composite material of the present application is to shape the carbon source before carbonization and activation pore formation, so that the carbon source is formed into a precursor powder with a preset shape. Compared with the solution of directly carbonizing and activating the carbon source without shaping, the solution of the present application first shapes and then activates the pore formation, so that the average aspect ratio AR of the multiple silicon-based particles 100 obtained can be in the range of 1.28≤AR≤10. By designing the preset shape of the precursor powder, the average aspect ratio AR of the multiple silicon-based particles 100 of the obtained silicon-carbon composite material can be in the range of 1.28≤AR≤10. As a result, the silicon-based particles 100 have a shorter ion transmission path from the surface to the center, which improves the dynamic performance of the battery using the silicon-carbon composite material. In addition, there are more contact points between adjacent silicon-based particles 100, and the conductive connection between adjacent silicon-based particles 100 is better, which improves the conductivity of the silicon-carbon composite material and improves the rate performance and cycle performance of the battery. Furthermore, the silicon-based particles 100 of the silicon-carbon composite material have a larger aspect ratio AR, so that when the silicon-based particles 100 are rolled on the negative electrode sheet, the silicon-based particles 100 are The long axis direction of 00 (i.e. the maximum length direction of the projection) tends to be parallel to the extension direction of the negative electrode current collector of the negative electrode plate, and the short axis direction of the silicon-based particle 100 (i.e. the minimum length direction of the projection) tends to be perpendicular to the extension direction of the negative electrode current collector (i.e. parallel to the thickness direction of the negative electrode plate, also called the Z-axis direction), thereby reducing the expansion rate of the negative electrode plate along the thickness direction during the process of metal ion insertion (such as lithium insertion), reducing the probability of damage to the silicon-based particle 100, and thus improving the cycle capacity retention rate of the battery.

[0117] Alternatively, the carbon source may include a deformable organic precursor, or an organic and inorganic composite precursor, or a mixture of multiple organic precursors.

[0118] Optionally, the organic precursor may include at least one of polymer-based organic matter, biomass-based organic matter, and organic matter containing heteroatoms.

[0119] Optionally, the polymer organic matter may include at least one of phenolic resin, polyimide, polystyrene, polycarbonate, polymethyl methacrylate, epoxy resin, polyacrylonitrile, polyaniline, polyetheretherketone, polyurethane, polypyrrole, asphalt, coal tar, etc.

[0120] Optionally, the biomass organic matter may include at least one of glucose, sucrose, starch, cellulose, lignin, chitosan, and the like.

[0121] Optionally, the organic substance containing heteroatoms may include at least one of melamine, dopamine, thiophenol, thiourea, and the like.

[0122] It should be noted that the carbon source in the examples of this application can be prepared by oneself or purchased from the market, and this application does not make any specific limitation on this.

[0123] Illustratively, the carbon source is phenolic resin, and providing the carbon source includes: dissolving phenol, formaldehyde and a catalyst in water, heating to 20° C. to 350° C. for polymerization reaction, and spray drying to obtain phenolic resin powder (ie, carbon source).

[0124] Specifically, the polymerization temperature can be, but is not limited to, 20° C., 50° C., 80° C., 100° C., 130° C., 150° C., 180° C., 200° C., 230° C., 250° C., 280° C., 300° C., 330° C., 350° C., etc. If the polymerization temperature is too low, the polymerization will be incomplete; if the polymerization temperature is too high, the generated phenolic resin will easily undergo thermal decomposition.

[0125] Optionally, the polymerization reaction time ranges from 20 min to 36 h. Specifically, the polymerization reaction time can be, but is not limited to, 20 min, 30 min, 50 min, 1 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 8 h, 10 h, 13 h, 15 h, 18 h, 20 h, 23 h, 25 h, 28 h, 30 h, 33 h, 36 h, etc.

[0126] Optionally, the catalyst may be, but is not limited to, an aqueous NaOH solution, an aqueous KOH solution, aqueous ammonia, or the like.

[0127] Optionally, the shape of the phenolic resin powder may be, but is not limited to, spherical.

[0128] In some embodiments, the ratio of the maximum length of the projection of the precursor powder to the minimum length of the projection of the precursor powder is between 1.28 and 10, and its proportion is greater than or equal to 50%.

[0129] Specifically, the ratio of the maximum length of the precursor powder projection to the minimum length of the precursor powder projection is between 1.28 and 10, and the proportion can be but not limited to 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 100%, etc.

[0130] Optionally, an average value of the ratio of the maximum length of the projection of the precursor powder to the minimum length of the projection of the precursor powder ranges from 1.28 to 10.

[0131] If the ratio of the maximum length of the precursor powder projection to the minimum length of the precursor powder projection is between 1.28 and 10, the average aspect ratio of the plurality of silicon-based particles 100 produced may be too large or too small. If the average aspect ratio AR of the plurality of silicon-based particles 100 is too small, the ion transmission path from the surface of the silicon-based particle 100 to the center of the silicon-based particle 100 becomes longer, reducing the dynamic performance of the battery using the silicon-carbon composite material. In addition, if the average aspect ratio AR of the plurality of silicon-based particles 100 is too small, there are too few contact points between adjacent silicon-based particles 100, and the conductive connection between adjacent silicon-based particles 100 is reduced, which reduces the conductivity of the silicon-carbon composite material, increases the impedance of the negative electrode sheet using the silicon-carbon composite material, and reduces the rate performance and cycle performance of the battery. Furthermore, if the average aspect ratio AR of the plurality of silicon-based particles 100 is too small, the orientation angle of the silicon-based particles 100 in the negative electrode sheet using the silicon-carbon composite material will increase the expansion rate of the silicon-carbon composite material after metal ion insertion (e.g., lithium insertion). If the average aspect ratio AR of the multiple silicon-based particles 100 is too large, the compressive resistance of the silicon-based particles 100 is reduced, so that when the negative electrode sheet is rolled during the process of making the silicon-carbon composite material into a negative electrode sheet, the silicon-based particles 100 are easily crushed; or the silicon-based particles 100 are easily broken during the battery cycle, and the electrolyte needs to be continuously consumed to repair the SEI film of the negative electrode sheet, which reduces the cycle performance of the battery.

[0132] In some embodiments, shaping the carbon source to form a precursor powder having a predetermined shape includes:

[0133] The carbon source is subjected to at least one process selected from the group consisting of hot pressing (also known as molding), molding, rolling, extrusion, ball milling, and electrospinning to shape the carbon source so that the carbon source forms a precursor powder having a preset shape.

[0134] Hot pressing can be used to produce oblate spherical precursor powders, while electrospinning can be used to produce rod-shaped precursor powders, allowing for better selection of processes based on desired shapes. Furthermore, hot pressing is simpler and less expensive than electrospinning.

[0135] In this embodiment, these processes are used to shape the carbon source, which is simple, easy to implement, and has a low preparation cost. In addition, these processes can better control the aspect ratio of the obtained precursor powder, thereby better controlling the average aspect ratio of the obtained silicon-based particles 100, so that the silicon-carbon composite material has higher cycle performance and rate performance.

[0136] In some embodiments, the carbon source is shaped so that the carbon source forms a precursor powder having a preset shape, comprising: applying a pressure of 0 MPa to 1000 MPa at a temperature of 0°C to 350°C and subjecting the carbon source to at least one of hot pressing, molding, rolling, extrusion, ball milling, and electrospinning to shape the carbon source so that the carbon source forms a precursor powder having a preset shape. In this embodiment, these processes are used to shape the carbon source, which is simple, easy to implement, and has a low preparation cost. In addition, these processes can better control the aspect ratio of the obtained precursor powder, thereby better controlling the average aspect ratio of the obtained silicon-based particles 100, so that the silicon-carbon composite material has higher cycle performance and rate performance. This embodiment controls the morphology of the cured resin or semi-cured resin (carbon source) by regulating the external force field and temperature to construct a precursor powder with a unique morphology.

[0137] Specifically, the shaping temperature may be, but is not limited to, 0° C., 10° C., 30° C., 50° C., 80° C., 100° C., 130° C., 150° C., 180° C., 200° C., 230° C., 250° C., 280° C., 300° C., 330° C., 350° C., etc. If the shaping temperature is too low, shaping is not conducive; if the shaping temperature is too high, shaping is also not conducive, and in addition, oxidation and thermal decomposition of the carbon source may occur, affecting the formation and performance of the final porous carbon framework 10.

[0138] Optionally, when the carbon source is phenolic resin, the shaping temperature ranges from 0° C. to 200° C. Further, when the carbon source is phenolic resin, the shaping temperature ranges from 80° C. to 180° C.

[0139] Optionally, when the carbon source is other than phenolic resin, the shaping temperature ranges from 0° C. to 350° C. Further, when the carbon source is other than phenolic resin, the shaping temperature ranges from 80° C. to 250° C.

[0140] Specifically, the shaping pressure may be, but is not limited to, 0 MPa, 1 MPa, 3 MPa, 5 MPa, 8 MPa, 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 80 MPa, 100 MPa, 200 MPa, 300 MPa, 400 MPa, 500 MPa, 600 MPa, 700 MPa, 800 MPa, 900 MPa, 1000 MPa, etc. If the shaping pressure is too low, shaping is not conducive; if the shaping pressure is too high, shaping is also not conducive; in addition, the shaping cost is increased, and the preparation cost of the porous carbon skeleton 10 is increased.

[0141] When the carbon source is shaped using the electrospinning process, no pressure needs to be applied, that is, the applied pressure is 0 MPa. In addition, the electrospinning process is carried out under the action of an electric field.

[0142] It should be noted that when the carbon source is shaped by the electrospinning process, the phenolic resin stock solution or the phenolic resin aqueous solution can be directly used for electrospinning, and the formed silk threads are then broken and spray-dried to obtain rod-shaped phenolic resin powder.

[0143] See Figure 5 In some embodiments, the precursor powder is a semi-cured resin. Before carbonizing and activating the precursor powder to form pores, the preparation method further includes:

[0144] S202', dispersing a precursor powder having a preset shape and a curing agent in a solvent, and curing at a temperature of 60°C to 180°C.

[0145] It should be noted that when the precursor powder is a curing resin, S202 ′ can be omitted.

[0146] Optionally, the curing degree of the semi-cured resin ranges from 70% to 80%; specifically, it can be, but is not limited to, 70%, 72%, 74%, 76%, 78%, 80%, etc.

[0147] Optionally, a precursor powder having a preset shape and a curing agent are dispersed in a solvent (e.g., water), placed at a temperature of 60°C to 180°C, stirred at 1000rpm to 5000rpm (e.g., 1000rpm, 2000rpm, 3000rpm, 4000rpm, 5000rpm, etc.), and the curing reaction is carried out for 30min to 10h (e.g., 30min, 1h, 3h, 5h, 7h, 10h, etc.).

[0148] Optionally, the curing agent may be, but is not limited to, at least one of an amine curing agent, an acidic curing agent, an alkaline curing agent, and a metal ion catalyst. Optionally, the acidic curing agent may be, but is not limited to, at least one of hydrochloric acid, oxalic acid, phosphoric acid, p-toluenesulfonic acid, and benzenesulfonic acid. The alkaline curing agent may be, but is not limited to, at least one of sodium hydroxide, potassium hydroxide, calcium oxide, aqueous ammonia, and sodium carbonate. The amine curing agent may be, but is not limited to, at least one of hexamethylenetetramine, ethylenediamine, and m-phenylenediamine. The metal ion catalyst may be, but is not limited to, at least one of zinc acetate and sodium carbonate.

[0149] Specifically, the curing temperature may be, but is not limited to, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, etc. If the curing temperature is too low, the reaction between the precursor powder and the curing agent is incomplete, affecting the mechanical strength and other properties of the porous carbon skeleton 10. If the curing temperature is too high, the curing agent may decompose and become ineffective. In addition, if the curing temperature is too high, the curing speed is too fast, the stress distribution of the precursor powder is uneven, and the precursor powder is prone to microcracks, which affects the mechanical strength of the porous carbon skeleton 10.

[0150] See Figure 6 In some embodiments, in S203, the carbonization and activation of the precursor powder to form pores to obtain the porous carbon skeleton 10 includes:

[0151] S2031, placing the precursor powder in an inert atmosphere and carbonizing it at a temperature of 400° C. to 1200° C. to obtain an intermediate carbon matrix; and

[0152] Optionally, the inert atmosphere may be nitrogen, argon, etc. The inert gas is used to isolate oxygen and protect the prepared intermediate carbon matrix.

[0153] Specifically, the carbonization temperature may be, but is not limited to, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, 1200°C, etc.

[0154] In this embodiment, if the carbonization temperature is too low, the carbonization of the intermediate carbon matrix is ​​incomplete, and too many non-carbon elements remain in the intermediate carbon matrix, which increases the side reaction between the silicon-based particles 100 and the battery electrolyte and reduces the initial efficiency of the battery. If the carbonization temperature is too high, the intermediate carbon matrix is ​​over-carbonized, the degree of graphitization is too high, and activation and pore formation are difficult, resulting in an excessively small pore volume of the porous carbon skeleton 10, which reduces the amount of silicon particles 20 that can be deposited in the porous carbon skeleton 10 and reduces the gram capacity of the silicon-based particles 100.

[0155] Optionally, the carbonization time ranges from 10 min to 100 h. Specifically, the carbonization time can be, but is not limited to, 10 min, 20 min, 30 min, 50 min, 1 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 10 h, 20 h, 30 h, 40 h, 50 h, 60 h, 70 h, 80 h, 90 h, 100 h, etc. If the carbonization time is too short, the carbonization of the intermediate carbon matrix is ​​incomplete, and too many non-carbon elements are retained in the intermediate carbon matrix, which increases the side reaction between the silicon-based particles 100 and the electrolyte of the battery and reduces the initial efficiency of the battery; if the carbonization time is too long, the intermediate carbon matrix is ​​over-carbonized and the degree of graphitization is too high, making it difficult to activate and form pores, so that the pore volume of the porous carbon skeleton 10 is too small, reducing the amount of silicon particles 20 that can be deposited in the porous carbon skeleton 10 and reducing the gram capacity of the silicon-based particles 100.

[0156] S2032 , placing the intermediate carbon matrix in a water vapor atmosphere, or a carbon dioxide atmosphere, or a strong alkaline solution at a temperature of 400° C. to 1200° C. for activation and pore formation, so as to obtain a porous carbon skeleton 10 .

[0157] It can be understood that the intermediate carbon matrix forms a porous carbon skeleton 10 after being activated and pore-formed.

[0158] Specifically, the activation pore-forming temperature may be, but is not limited to, 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700° C., 750° C., 800° C., 850° C., 900° C., 950° C., 1000° C., 1050° C., 1100° C., 1150° C., 1200° C., etc. If the activation pore-forming temperature is too low, the activation reaction degree of the intermediate carbon matrix is ​​insufficient, and sufficient pores 11 cannot be formed. The porosity 11 ratio of the porous carbon skeleton 10 obtained is too low, the pore volume is too small, and the amount of silicon particles 20 that can be deposited in the pores 11 of the porous carbon skeleton 10 is too small, thereby reducing the gram capacity of the silicon-based particles 100 obtained. If the activation pore-forming temperature is too high, the pores 11 of the porous carbon skeleton 10 obtained will become larger and the pore size distribution will become wider. After the silicon particles 20 are deposited in the porous carbon skeleton 10, the size of the silicon particles 20 will easily become too large and the size distribution of the silicon particles 20 will become wider. They will easily break during the lithium insertion and delithiation process, resulting in excessive volume deformation, which is not easy to be buffered by the surrounding pores 11, thereby increasing the expansion rate of the silicon-based particles 100 and reducing the battery cycle performance using the silicon-carbon composite material.

[0159] Alternatively, the activation pore-forming time may be 10 min to 100 h. Specifically, the activation pore-forming time may be, but is not limited to, 10 min, 20 min, 30 min, 50 min, 1 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, 10 h, 20 h, 30 h, 40 h, 50 h, 60 h, 70 h, 80 h, 90 h, 100 h, etc. If the activation pore-forming time is too short, the pores 11 of the porous carbon skeleton 10 obtained are easily unevenly distributed, the porosity 11 rate is too low, the pore volume is too small, and the amount of silicon particles 20 that can be deposited in the pores 11 of the porous carbon skeleton 10 is too small, thereby reducing the gram capacity of the silicon-based particles 100 obtained. If the activation and pore-forming time is too long, the pores 11 of the porous carbon skeleton 10 obtained will easily become larger and the pore size distribution will become wider. After the silicon particles 20 are deposited in the porous carbon skeleton 10, the size of the silicon particles 20 will easily become too large and the size distribution of the silicon particles 20 will become wider. They will easily break during the lithium insertion and delithiation process, resulting in excessive volume deformation, which is not easy to be buffered by the surrounding pores 11, thereby increasing the expansion rate of the silicon-based particles 100 and reducing the battery cycle performance using the silicon-carbon composite material.

[0160] Optionally, when the intermediate carbon matrix is ​​activated in a water vapor atmosphere or a carbon dioxide atmosphere for pore formation, the activation temperature is 400° C. to 1100° C. When the intermediate carbon matrix is ​​activated in a strong base for pore formation, the activation temperature is 400° C. to 1200° C.

[0161] Optionally, when the intermediate carbon matrix is ​​placed in a strong base for activation and pore formation, the intermediate carbon matrix is ​​first mixed with the strong base and then placed at a temperature of 400° C. to 1200° C. for activation and pore formation to obtain the porous carbon skeleton 10 .

[0162] Optionally, the strong alkaline solution may be, but is not limited to, at least one of a sodium hydroxide solution, a potassium hydroxide solution, and a lithium hydroxide solution.

[0163] Optionally, the mass ratio of the intermediate carbon matrix to the strong base is in the range of 0.2 to 2. Specifically, the mass ratio of the intermediate carbon matrix to the strong base can be, but is not limited to, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2, etc. If the mass ratio of the intermediate carbon matrix to the strong base is too small, the amount of strong base added is too much, which will cause the pores 11 of the porous carbon skeleton 10 to become larger and the pore size distribution to become wider. After the silicon particles 20 are deposited in the porous carbon skeleton 10, the size of the silicon particles 20 is easily made too large, the size distribution of the silicon particles 20 is widened, and the silicon particles 20 are easily broken during the lithium insertion and delithiation process, resulting in excessive volume deformation, which is not easily buffered by the surrounding pores 11, thereby increasing the expansion rate of the silicon-based particles 100 and reducing the cycle performance of the battery using the silicon-carbon composite material. If the mass ratio of the intermediate carbon matrix to the strong base is too large, the amount of strong base added is too small, resulting in insufficient activation reaction of the intermediate carbon matrix, and failure to form enough pores 11. The porosity 11 rate of the porous carbon skeleton 10 obtained is too low, and the pore volume is too small. The amount of silicon particles 20 that can be deposited in the pores 11 of the porous carbon skeleton 10 is too small, thereby reducing the gram capacity of the silicon-based particles 100 obtained.

[0164] In some embodiments, in S204, depositing a plurality of silicon particles 20 in the plurality of pores 11 of the porous carbon skeleton 10 includes:

[0165] A first mixed gas is introduced into the porous carbon skeleton 10 and placed at a temperature of 400° C. to 800° C. to perform a first chemical vapor deposition to deposit a plurality of silicon particles 20 in the plurality of pores 11 of the porous carbon skeleton 10 , wherein the first mixed gas includes silane and a first protective gas.

[0166] Optionally, the first mixed gas includes silane and a first protective gas.

[0167] Optionally, the silane may include but is not limited to at least one of monosilane, disilane, dichlorosilane, trichlorosilane, and the like.

[0168] Optionally, the first protective gas may be, but is not limited to, at least one of nitrogen, argon, and the like.

[0169] Specifically, the temperature of the first chemical vapor deposition can be, but is not limited to, 400°C, 430°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 580°C, 600°C, 630°C, 650°C, 680°C, 700°C, 730°C, 750°C, 780°C, 800°C, etc. If the temperature of the first chemical vapor deposition is too low, silane is difficult to be completely reduced, resulting in low production capacity. If the temperature of the first chemical vapor deposition is too high, the silicon particles 20 are easily converted from amorphous silicon to crystalline silicon, thereby making the silicon particles 20 have expansion anisotropy, increasing the expansion rate of the silicon particles 20 when lithium is inserted, and also easily generating chemically inert silicon carbide, thereby reducing the energy density of the silicon-based particles 100.

[0170] Optionally, the time of the first chemical vapor deposition is 10 minutes to 100 hours. Specifically, the time of the first chemical vapor deposition can be, but is not limited to, 10 minutes, 20 minutes, 30 minutes, 50 minutes, 1 hour, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, 100 hours, etc. If the time of the first chemical vapor deposition is too short, the silicon particles 20 cannot be completely deposited in the multiple pores 11 of the porous carbon skeleton 10, which easily makes the deposition of the silicon particles 20 in the porous carbon skeleton 10 uneven. If the first chemical vapor deposition time is too long, silicon particles 20 are easily deposited on the surface of the porous carbon skeleton 10, so that the silicon particles 20 on the surface of the porous carbon skeleton 10 have no buffer space when lithium is embedded, thereby increasing the expansion rate of the silicon-based particles 100 and reducing the service life of the silicon-based particles 100.

[0171] See Figure 7 , an embodiment of the present application provides a method for preparing a silicon-carbon composite material, the preparation method further comprising:

[0172] S301, providing a carbon source;

[0173] S302, shaping the carbon source to form a precursor powder having a preset shape;

[0174] S303, carbonizing and activating the precursor powder to form pores to obtain a porous carbon skeleton 10, wherein the porous carbon skeleton 10 has a plurality of pores 11; and

[0175] S304, depositing a plurality of silicon particles 20 in the plurality of pores 11 of the porous carbon skeleton 10; and

[0176] For detailed descriptions of other aspects of S301 to S304 , please refer to the descriptions of the corresponding parts of the above embodiments, which will not be repeated here.

[0177] S305 , depositing a carbon coating layer 30 on the surface of the porous carbon skeleton 10 having the plurality of silicon particles 20 to obtain a silicon-carbon composite material.

[0178] Optionally, the depositing of a carbon coating layer 30 on the surface of the porous carbon skeleton 10 having a plurality of silicon particles 20 includes: introducing a second mixed gas into the porous carbon skeleton 10 having a plurality of silicon particles 20, and placing the mixture at a temperature of 400°C to 1000°C for performing a second chemical vapor deposition to form a carbon coating layer 30 on the surface of the porous carbon skeleton 10, wherein the second mixed gas includes an organic gas source and a second protective gas to obtain a silicon-carbon composite material.

[0179] Among them, the silicon-carbon composite material includes a plurality of silicon-based particles 100, the silicon-based particles 100 include a porous carbon skeleton 10, a plurality of silicon particles 20 and a carbon coating layer 30, the average aspect ratio AR of the plurality of silicon-based particles 100 is in the range of 1.28≤AR≤10, the average aspect ratio AR of the plurality of silicon-based particles 100 is AR=Lmax / Lmin, the average maximum length of the projections of the plurality of silicon-based particles 100 is Lmax, and the average minimum length of the projections of the plurality of silicon-based particles 100 is Lmin.

[0180] Optionally, the organic gas source may include but is not limited to at least one of acetylene, ethylene, methane, etc.

[0181] Optionally, the second protective gas may be, but is not limited to, at least one of nitrogen, argon, and the like.

[0182] Optionally, the temperature of the second chemical vapor deposition may be, but is not limited to, 400°C, 430°C, 450°C, 460°C, 470°C, 480°C, 490°C, 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, 580°C, 600°C, 630°C, 650°C, 680°C, 700°C, 730°C, 750°C, 780°C, 800°C, 850°C, 900°C, 950°C, 1000°C, etc. If the temperature of the second chemical vapor deposition is too low, the organic gas source is difficult to be reduced, and it is difficult to form the carbon coating layer 30. The carbon coating layer 30 is difficult to completely cover the porous carbon skeleton 10, so that part of the silicon particles 20 are exposed, thereby increasing the side reaction between the silicon particles 20 and the electrolyte; if the temperature of the second chemical vapor deposition is too high, inert silicon carbide is easily generated, which reduces the energy density of the silicon-based particles 100.

[0183] Optionally, the second chemical vapor deposition time is 10 minutes to 100 hours. Specifically, the second chemical vapor deposition time can be, but is not limited to, 10 minutes, 20 minutes, 30 minutes, 50 minutes, 1 hour, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 10 hours, 20 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 90 hours, 100 hours, etc. If the second chemical vapor deposition time is too short, the organic gas source is difficult to be reduced, and the carbon coating layer 30 is difficult to completely cover the porous carbon skeleton 10, so that part of the silicon particles 20 is exposed, thereby increasing the side reaction between the silicon particles 20 and the electrolyte; if the second chemical vapor deposition time is too long, inert silicon carbide is easily generated, and the formed carbon coating layer 30 is too thick, which reduces the energy density of the silicon-based particles 100.

[0184] See Figure 8 The embodiment of the present application further provides a negative electrode plate 400 , which includes a negative electrode current collector 410 and a negative electrode active layer 420 , and the negative electrode active layer 420 includes the silicon-carbon composite material described in the embodiment of the present application.

[0185] It should be noted that the negative electrode active layer 420 can be arranged on one surface or multiple surfaces of the negative electrode current collector 410. In the drawings and descriptions of this application, the negative electrode active layer 420 is arranged on two opposite surfaces of the negative electrode current collector 410 as an example, which should not be understood as a limitation on the negative electrode plate 400 of this application.

[0186] Optionally, the negative electrode current collector 410 may be, but is not limited to, copper foil or copper sheet.

[0187] Optionally, the negative electrode active layer 420 may include a negative electrode active material, a negative electrode conductor, and a negative electrode binder.

[0188] Optionally, the negative electrode active material includes at least one of the silicon-carbon composite material, graphite, and the like.

[0189] Optionally, the negative electrode conductive agent may be, but is not limited to, at least one of conductive carbon black (SP for short), acetylene black, carbon nanotubes (CNTs), carbon fibers, graphene, and the like.

[0190] Optionally, the negative electrode binder may be, but is not limited to, at least one of polyacrylic acid (PAA), styrene butadiene rubber (SBR), polyvinylidene fluoride (PVDF), sodium carboxymethyl cellulose (CMC), and the like.

[0191] See Figure 9 and Figure 10 The present embodiment further provides a battery 500, comprising an electrolyte, a positive electrode sheet 510, a separator 520, and the negative electrode sheet 400 described in the embodiment of the present application. The positive electrode sheet 510 is at least partially immersed in the electrolyte; the separator 520 is located on one side of the positive electrode sheet 510 and is at least partially immersed in the electrolyte; the negative electrode sheet 400 is disposed on a side of the separator 520 facing away from the positive electrode sheet 510 and is at least partially immersed in the electrolyte.

[0192] The battery 500 in the embodiment of the present application may be, but is not limited to, a lithium-ion secondary battery, a lithium-ion primary battery, a lithium-sulfur battery, a sodium-lithium-ion battery, or the like.

[0193] Optionally, the battery 500 may be, but is not limited to, at least one of a cylindrical battery, a square battery, a blade battery, etc. The drawings in this application illustrate only one or more possible forms of the battery 500 and should not be construed as limiting the battery 500 of the embodiments of this application.

[0194] It can be understood that the positive electrode sheet 510 and the negative electrode sheet 400 are respectively located on opposite sides of the separator 520 , that is, the separator 520 is located between the positive electrode sheet 510 and the negative electrode sheet 400 to separate the positive electrode sheet 510 from the negative electrode sheet 400 .

[0195] Optionally, the positive electrode sheet 510, separator 520, and negative electrode sheet 400 are stacked in sequence to form an electrode assembly, which is then wound as a whole to form a battery cell. It should be noted that the positive electrode sheet 510 and the negative electrode sheet 400 can be collectively referred to as electrode sheets. In other words, the electrode sheet includes the positive electrode sheet 510 and the negative electrode sheet 400.

[0196] Optionally, the electrolyte includes an electrolyte salt and an organic solvent. Optionally, the electrolyte salt may be, but is not limited to, lithium hexafluorophosphate (LiPF6).

[0197] Alternatively, the organic solvent comprises at least one of a linear carbonate and a cyclic carbonate. Alternatively, the cyclic carbonate may include but is not limited to at least one of ethylene carbonate (abbreviated as EC), propylene carbonate (abbreviated as PC) etc. The dielectric constant of ethylene carbonate is much greater than that of propylene carbonate, and ethylene carbonate can better promote the formation of SEI film. Alternatively, the linear carbonate may include but is not limited to at least one of dimethyl carbonate (abbreviated as DMC), diethyl carbonate (abbreviated as DEC), ethyl methyl carbonate (abbreviated as EMC) etc.

[0198] Optionally, the electrolyte further includes a film-forming additive, which can be used to promote the formation of a SEI film on at least one of the positive electrode sheet 510 and the negative electrode sheet 400 and maintain the stability of the SEI film.

[0199] Optionally, the film-forming additive includes at least one of fluoroethylene carbonate (FEC), diethylene sulfate (DTD), vinylene carbonate (VC), and the like.

[0200] Optionally, the diaphragm 520 may be, but is not limited to, at least one of a polypropylene film (PP film for short), a polyethylene film (PE film for short), a ceramic diaphragm 520 , and the like.

[0201] See Figure 11 Optionally, the positive electrode sheet 510 includes a positive electrode current collector 511 and a positive electrode active layer 512, wherein the positive electrode active layer 512 is disposed on the surface of the positive electrode current collector 511. It is understood that the positive electrode active layer 512 may cover one surface or two opposite surfaces of the positive electrode current collector 511.

[0202] Optionally, the positive electrode current collector 511 may be, but is not limited to, an aluminum sheet, aluminum foil, or the like.

[0203] Optionally, the positive electrode active layer 512 includes a positive electrode active material, a positive electrode conductor, a positive electrode binder, and a positive electrode thickener.

[0204] Optionally, the positive electrode active material may be, but is not limited to, lithium cobalt oxide.

[0205] Optionally, the positive electrode conductive agent may be, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, carbon fibers, graphene, and the like.

[0206] Optionally, the positive electrode binder may be, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyvinylether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene butadiene rubber (SBR).

[0207] Please see again Figure 9 and Figure 10Optionally, the battery 500 further includes a housing 540 , wherein the housing 540 has a closed receiving cavity 541 , and the receiving cavity 541 is used to receive the electrolyte, the positive electrode sheet 510 , the diaphragm 520 and the negative electrode sheet 400 .

[0208] The silicon-carbon composite material and battery of the present application are further described below through specific examples.

[0209] Example 1 to Example 11

[0210] The silicon-carbon composite material of each embodiment is prepared by the following steps:

[0211] (1) Phenol (100 g), formaldehyde solution (37%, 120 mL) and ammonia water (25%, 3.5 mL) were dissolved in deionized water and stirred at 85°C for 8 hours. The reaction solution was spray-dried to obtain spherical phenolic resin powder (i.e., carbon source);

[0212] (2) then hot-pressing the phenolic resin powder at 120° C. and 15 MPa for 2 hours to obtain a phenolic resin powder having a predetermined shape (i.e., a precursor powder);

[0213] (3) carbonizing the phenolic resin powder having a predetermined shape at 800° C. for 3 hours;

[0214] (4) introducing water vapor at 500° C. for 30 minutes to activate and form pores, thereby forming a porous carbon skeleton 10 having a plurality of pores 11;

[0215] (5) introducing a mixture of monosilane and nitrogen at 550° C. and performing a deposition reaction for 24 hours to deposit silicon particles 20 in the pores 11 of the porous carbon skeleton 10; and

[0216] (6) Heating to 650° C. and introducing acetylene gas for 2 h to form a carbon coating layer 30 on the surface of the porous carbon skeleton 10 having silicon particles 20, and cooling to obtain a silicon-carbon composite material.

[0217] The average aspect ratio AR of the silicon-carbon composite materials prepared in various embodiments and the average value of the area ratio of the curvature H≥0 on the surface of the plurality of silicon-based particles 100 are shown in Table 1 below.

[0218] Example 12

[0219] The silicon-carbon composite material of this embodiment is prepared by the following steps:

[0220] (1) Phenol (100 g), formaldehyde solution (37%, 120 mL) and ammonia water (25%, 3.5 mL) were dissolved in deionized water and stirred at 85°C for 8 hours. The reaction solution was spray-dried to obtain spherical phenolic resin powder (i.e., carbon source);

[0221] (2) rolling the phenolic resin powder at 150° C. and 200 MPa to obtain a phenolic resin powder (i.e., precursor powder) having a predetermined shape;

[0222] (3) carbonizing the phenolic resin powder having a predetermined shape at 800° C. for 3 hours;

[0223] (4) introducing water vapor at 500° C. for 30 minutes to activate and form pores, thereby forming a porous carbon skeleton 10 having a plurality of pores 11;

[0224] (5) introducing a mixture of monosilane and nitrogen at 550° C. and performing a deposition reaction for 24 hours to deposit silicon particles 20 in the pores 11 of the porous carbon skeleton 10; and

[0225] (6) Heating to 650° C. and introducing acetylene gas for 2 h to form a carbon coating layer 30 on the surface of the porous carbon skeleton 10 having silicon particles 20, and cooling to obtain a silicon-carbon composite material.

[0226] Example 13

[0227] The silicon-carbon composite material of this embodiment is prepared by the following steps:

[0228] (1) Phenol (100 g), formaldehyde solution (37%, 120 mL) and ammonia water (25%, 3.5 mL) were dissolved in deionized water and stirred and polymerized at 85°C for 6 hours to obtain a phenolic resin stock solution;

[0229] (2) electrospinning the phenolic resin stock solution, and crushing the resulting filaments to obtain phenolic resin powder (i.e., precursor powder) having a predetermined shape;

[0230] (3) mixing the phenolic resin powder having a predetermined shape with a water solvent and hexamethylenetetramine, heating the mixture to 90° C. and stirring the mixture for 3 h at a stirring rate of 2000 rpm to allow the phenolic resin powder and the hexamethylenetetramine to undergo a curing reaction;

[0231] (4) carbonizing the cured phenolic resin powder at 800° C. for 3 hours;

[0232] (5) introducing water vapor at 500° C. for 30 minutes to activate and form pores, thereby forming a porous carbon skeleton 10 having a plurality of pores 11;

[0233] (6) introducing a mixture of monosilane and nitrogen at 550° C. and performing a deposition reaction for 24 hours to deposit silicon particles 20 in the pores 11 of the porous carbon skeleton 10; and

[0234] (7) Heating to 650° C. and introducing acetylene gas for 2 h to form a carbon coating layer 30 on the surface of the porous carbon skeleton 10 having silicon particles 20, and cooling to obtain a silicon-carbon composite material.

[0235] Comparative Example 1

[0236] The silicon-carbon composite material of each embodiment is prepared by the following steps:

[0237] (1) Phenol (100 g), formaldehyde solution (37%, 120 mL) and ammonia water (25%, 3.5 mL) were dissolved in deionized water and stirred at 85°C for 8 hours. The reaction solution was spray-dried to obtain phenolic resin powder (i.e., carbon source);

[0238] (2) carbonizing the phenolic resin powder at 800° C. for 3 hours;

[0239] (3) introducing water vapor at 500° C. for 30 minutes to activate and form pores, thereby forming a porous carbon skeleton 10 having a plurality of pores 11;

[0240] (4) introducing a mixture of monosilane and nitrogen at 550° C. and performing a deposition reaction for 24 hours to deposit silicon particles 20 in the pores 11 of the porous carbon skeleton 10; and

[0241] (5) Heating to 650° C. and introducing acetylene gas for 2 h to form a carbon coating layer 30 on the surface of the porous carbon skeleton 10 having silicon particles 20, and cooling to obtain a silicon-carbon composite material.

[0242] Comparative Example 2

[0243] The silicon-carbon composite material of this comparative example is different from that of Example 1 in that, after hot pressing, the average aspect ratio of the phenolic resin powder is different, so that the average aspect ratio of the prepared silicon-carbon composite material is as shown in Table 1 below.

[0244] Comparative Example 3

[0245] The difference between the silicon-carbon composite material in this comparative example and Example 4 is that after hot pressing treatment, the average value of the area ratio of the curvature H≥0 on the surface of the phenolic resin powder is different, so that the average value of the area ratio of the curvature H≥0 on the surface of the prepared silicon-carbon composite material is different from that in Example 4.

[0246] Comparative Example 4

[0247] The silicon-carbon composite material of each embodiment is prepared by the following steps:

[0248] (1) Phenol (100 g), formaldehyde solution (37%, 120 mL) and ammonia water (25%, 3.5 mL) were dissolved in deionized water and stirred at 85°C for 15 hours. The reaction solution was spray-dried to obtain phenolic resin powder (i.e., carbon source);

[0249] (2) crushing the phenolic resin powder by air flow to form irregular phenolic resin powder;

[0250] (3) carbonizing the irregular phenolic resin powder at 800° C. for 3 hours;

[0251] (4) introducing water vapor at 500° C. for 30 minutes to activate and form pores, thereby forming a porous carbon skeleton 10 having a plurality of pores 11;

[0252] (5) introducing a mixture of monosilane and nitrogen at 550° C. and performing a deposition reaction for 24 hours to deposit silicon particles 20 in the pores 11 of the porous carbon skeleton 10; and

[0253] (6) Heating to 650° C. and introducing acetylene gas for 2 h to form a carbon coating layer 30 on the surface of the porous carbon skeleton 10 having silicon particles 20, and cooling to obtain a silicon-carbon composite material.

[0254] The silicon-carbon composite materials obtained in each embodiment and comparative example are assembled into a battery 500 according to the following steps: (1) Preparation of negative electrode sheet 400: Silicon-carbon composite material (negative electrode active material), graphite (negative electrode active material), PAA (negative electrode binder), and carbon nanotubes CNT (negative electrode conductive agent) are mixed in a mass ratio of 10:87:2.8:0.2 to prepare negative electrode slurry, and the negative electrode slurry is coated on copper foil (negative electrode current collector 410), dried at 100°C, and rolled with a pressure of 5t, and then cut into strips and sheets to obtain negative electrode sheet 400; (2) Preparation of positive electrode sheet 510 Preparation: Lithium cobalt oxide (positive electrode active material) is mixed with carbon nanotubes CNT (positive electrode conductive agent) and PVDF (positive electrode binder) in a mass ratio of 98:1:1 to prepare a positive electrode slurry, which is then coated on aluminum foil (positive electrode current collector 511), dried, rolled, slit, and cut to obtain a positive electrode sheet 510; (3) a polyethylene porous film is used as a separator 520, the positive electrode sheet 510, the separator 520, and the negative electrode sheet 400 are stacked in sequence and wound into a battery cell, which is then packaged with aluminum-plastic film, dried, injected (electrolyte injected), formed, secondary packaged, and capacity divided to obtain a battery 500.

[0255] The following performance tests were performed on the silicon-carbon composite materials and the battery 500 of each embodiment and comparative example:

[0256] (1) Average aspect ratio: measured using a scanning electron microscope (SEM).

[0257] (2) Average area ratio of curvature H ≥ 0 on the surface of silicon-based particles 100: Measurements were performed using a scanning electron microscope (SEM) to capture SEM images. Each image included at least 100 silicon-based particles 100. The average value was calculated based on the percentage of H ≥ 0 on a two-dimensional plane for each silicon-based particle 100 in the SEM image. Because the orientations and angles of multiple silicon-based particles 100 may vary, the calculated average value can effectively measure the average area ratio of curvature H ≥ 0 on the surface of the silicon-based particles 100.

[0258] (3) Rate performance test: Battery 500 was charged to 4.48 V at 0.2 C constant current and constant voltage, with a cut-off current of 0.02 C, and allowed to stand for 10 min. It was then discharged to 3.0 V at 0.2 C, and allowed to stand for 10 min. The discharge capacity was recorded as the initial discharge capacity. It was then charged to 4.48 V at 3 C constant current and constant voltage, with a cut-off current of 0.02 C, and allowed to stand for 10 min. It was then discharged to 3.0 V at 0.2 C, and allowed to stand for 10 min. The discharge capacity was recorded as the 3 C discharge capacity.

[0259] 3C capacity retention rate = 100% × 3C discharge capacity / initial discharge capacity.

[0260] The 3C capacity retention rate was used to measure the rate performance of the battery 500 of each embodiment and comparative example.

[0261] (4) Cycle capacity retention rate: Battery 500 was subjected to a charge and discharge cycle test on a charge and discharge instrument at a test temperature of 25°C. Battery 500 was charged to 4.48V at a constant current and constant voltage of 3C, with a cut-off current of 0.02C, and allowed to stand for 10 minutes; then discharged to 3.0V at a constant current and constant voltage of 0.5C, and allowed to stand for 10 minutes. The charge and discharge cycles were repeated 500 times, and the discharge capacity of the 500th cycle was recorded.

[0262] Cycle capacity retention rate=(discharge capacity at the 500th cycle / initial discharge capacity)×100%.

[0263] (5) Expansion rate after 500 cycles: Expansion rate = thickness of the battery at full charge after 500 cycles / thickness of the battery at initial full charge.

[0264] The measurement results of each embodiment and comparative example are shown in Table 1 below.

[0265] Table 1 Performance parameters of the silicon-carbon composite material and battery 500 of each embodiment and comparative example

[0266]

[0267] From the test results of Examples 1 to 8, Comparative Examples 1 and 2 in Table 1, it can be seen that when the average value of the area ratio of the curvature H ≥ 0 on the surface of the silicon-based particles 100 is basically the same, as the average aspect ratio AR of the silicon-based particles 100 increases, the 3C capacity retention rate of the battery 500 gradually increases, and then the increase trend gradually slows down. When the average aspect ratio AR of the silicon-based particles 100 further increases, the 3C capacity retention rate of the battery 500 slightly decreases. In addition, when the average value of the area ratio of the curvature H ≥ 0 on the surface of the silicon-based particles 100 is similar, as the average aspect ratio AR of the silicon-based particles 100 increases, the cycle capacity retention of the battery 500 after 500 cycles first gradually increases, then gradually decreases, and the expansion of the battery 500 after 500 cycles first gradually decreases, and then gradually increases. When the average aspect ratio AR of the silicon-based particles 100 ranges from 1.3 to 10, the battery 500 has a higher 3C capacity retention rate (better rate performance), a higher 500-cycle capacity retention rate, and a lower 500-cycle expansion rate.

[0268] From the test results of Examples 4, 9 to 11 and Comparative Example 3, it can be seen that when the average aspect ratio AR of the silicon-based particles 100 remains unchanged, as the average value of the area ratio of the curvature H≥0 on the surface of the silicon-based particles 100 increases, the 3C capacity retention rate of the battery 500 changes little, but the cycle capacity retention rate of the battery 500 after 500 cycles gradually increases, and the expansion rate of the battery 500 after 500 cycles gradually decreases. When the average value of the area ratio of the curvature H≥0 on the surface of the silicon-based particles 100 is too low (such as in Comparative Example 3), the cycle capacity retention rate of the battery 500 after 500 cycles is greatly reduced, and the expansion rate of the battery 500 after 500 cycles increases.

[0269] It can be seen from the test results of Comparative Example 4 that when the average aspect ratio AR of the silicon-based particles 100 is too small and the average value of the area proportion of the curvature H≥0 on the surface of the silicon-based particles 100 is also too small, the 3C capacity retention rate and 500 cycle capacity retention rate of the battery 500 are greatly reduced, and the 500 cycle expansion rate of the battery 500 is greatly increased.

[0270] From the test results of Examples 1 to 13, it can be seen that when the average aspect ratio AR of the silicon-based particles 100 is 1.3 to 10, and the average value of the area proportion of the curvature H≥0 on the surface of the silicon-based particles 100 is greater than or equal to 70%, the battery 500 has a higher 3C capacity retention rate, a higher 500 cycle capacity retention rate, and a lower 500 cycle expansion rate.

[0271] See Figure 12The embodiment of the present application further provides an electronic device 600 , which includes a device body 610 and the battery 500 described in the embodiment of the present application, and the battery 500 is used to power the device body 610 .

[0272] The electronic device 600 of the embodiment of the present application can be, but is not limited to, a portable electronic device 600 such as a mobile phone, a tablet computer, a laptop computer, a desktop computer, a smart toy, smart glasses, a smart bracelet, a smart watch, an e-reader, a game console, or a toy.

[0273] For a detailed description of the battery 500 , please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0274] It can be understood that the electronic device 600 described in this embodiment is merely a form of electronic device 600 used by the battery 500, and should not be understood as a limitation on the electronic device 600 provided in this application, nor should it be understood as a limitation on the battery 500 provided in each embodiment of this application.

[0275] See Figure 13 and Figure 14 Optionally, the device body 610 of the embodiment of the present application further includes a display screen 611, a middle frame 613, and a housing 615. The housing 615 is disposed opposite to the display screen 611, the middle frame 613 is located between the display screen 611 and the housing 615, and the sidewalls of the middle frame 613 are exposed to the display screen 611 and the housing 615. The middle frame 613 and the housing 615 enclose an accommodating space, and the accommodating space is used to accommodate the battery 500. The display screen 611 is electrically connected to the battery 500, and the battery 500 provides power for the display screen 611.

[0276] Optionally, the display screen 611 may be, but is not limited to, one or more of a liquid crystal display screen, a light emitting diode display screen (LED display screen), a micro light emitting diode display screen (Micro LED display screen), a sub-millimeter light emitting diode display screen (Mini LED display screen), an organic light emitting diode display screen (OLED display screen), etc.

[0277] Optionally, the device body 610 of the present application further includes a processor 616 and a memory 617. The processor 616 and the memory 617 are disposed in the accommodation space, and the processor 616 is electrically connected to the battery 500, the display screen 611, and the memory 617, respectively. The processor 616 is configured to control the display screen 611 for display, and the memory 617 is configured to store program codes required for the operation of the processor 616, program codes required to control the display screen 611, and display content of the display screen 611.

[0278] Optionally, the processor 616 includes one or more general-purpose processors, where a general-purpose processor can be any type of device capable of processing electronic instructions, including a central processing unit (CPU), a microprocessor, a microcontroller, a main processor, a controller, and an ASIC. The processor 616 is used to execute various types of digital storage instructions, such as software or firmware programs stored in the memory 617, which enables the computing device to provide a wide variety of services.

[0279] Optionally, the memory 617 may include volatile memory, such as random access memory (RAM); the memory 617 may also include non-volatile memory (NVM), such as read-only memory (ROM), flash memory (FM), hard disk drive (HDD), or solid-state drive (SSD). The memory 617 may also include a combination of the above types of memory 617.

[0280] In some embodiments, the device body 610 of the present embodiment further includes a camera module 618, which is disposed in the accommodation space. The camera module 618 is electrically connected to the processor 616 and the battery 500, respectively, for capturing images under the control of the processor 616. The battery 500 also provides power to the camera module 618.

[0281] Optionally, the housing 615 has a light-transmitting portion (not shown), and the camera module 618 can capture images through the light-transmitting portion on the housing 615. That is, the camera module 618 in this embodiment is a rear-facing camera module 618. It is understood that in other embodiments, the light-transmitting portion can be provided on the display screen 611, that is, the camera module 618 is a front-facing camera module 618. In the schematic diagram of this embodiment, the light-transmitting portion is illustrated as an opening. In other embodiments, the light-transmitting portion may not be an opening, but may be made of a light-transmitting material, such as plastic or glass.

[0282] Mentioning "embodiments" and "implementation methods" in this application means that the specific features, structures or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrases in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments. In addition, it should be understood that the features, structures or characteristics described in the various embodiments of the present application can be arbitrarily combined to form another embodiment that does not deviate from the spirit and scope of the technical solution of the present application, unless there is a contradiction between them.

[0283] Finally, it should be noted that the above implementation modes are only used to illustrate the technical solutions of the present application and are not limiting. Although the present application has been described in detail with reference to the above preferred implementation modes, ordinary technicians in this field should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A silicon-carbon composite material, characterized in that: The silicon-carbon composite material includes a plurality of silicon-based particles, the average maximum length of the projections of the plurality of silicon-based particles is Lmax, the average minimum length of the projections of the plurality of silicon-based particles is Lmin, and the average aspect ratio AR of the plurality of silicon-based particles is AR=Lmax / Lmin. Then, the range of the average aspect ratio AR of the plurality of silicon-based particles is 1.28≤AR≤10.

2. The silicon-carbon composite material according to claim 1, characterized in that The curvature of any point on the surface of the silicon-based particle is H, and an average value of area proportions of curvature H≧0 on the surfaces of the plurality of silicon-based particles is greater than or equal to 70%.

3. The silicon-carbon composite material according to claim 1, characterized in that An average maximum length Lmax of the projections of the plurality of silicon-based particles is in the range of 1 μm≤Lmax≤20 μm.

4. The silicon-carbon composite material according to claim 1, characterized in that An average minimum length Lmin of the projections of the plurality of silicon-based particles is in the range of 0.1 μm≤Lmin≤10 μm.

5. The silicon-carbon composite material according to claim 1, characterized in that The silicon-based particles include: A porous carbon skeleton having a plurality of pores; and a plurality of silicon particles, wherein the plurality of silicon particles are distributed in the plurality of pores of the porous carbon skeleton; Wherein, the mass fraction of the silicon particles in the silicon-based particles ranges from 5% to 95%.

6. The silicon-carbon composite material according to claim 5, characterized in that The average size of the silicon particles ranges from 0.2 nm to 20 nm.

7. The silicon-carbon composite material according to claim 5, characterized in that The porous carbon skeleton satisfies at least one of the following conditions: The porosity of the porous carbon skeleton ranges from 20% to 99%; The average pore size of the pores ranges from 0.4 nm to 20 nm; and The pore volume of the porous carbon skeleton is in the range of 0.1 cm 3 / g to 5.5cm 3 / g.

8. The silicon-carbon composite material according to claim 5, characterized in that The silicon-based particles further include a carbon coating layer, which is wrapped around the surface of the porous carbon skeleton. The thickness of the carbon coating layer is in a range of 1 nm to 1 μm.

9. The silicon-carbon composite material according to claim 1, characterized in that The specific surface area S of the silicon-based particles is in the range of 0.5 m2 / g≤S≤30 m2 / g.

10. The silicon-carbon composite material according to any one of claims 1 to 9, characterized in that: The shape of the silicon-based particles includes at least one of an oblate spheroid, an ellipsoid, a plate, a flake, a cuboid, a rod, a column, a needle, and a fiber.

11. A method for preparing a silicon-carbon composite material, characterized in that: include: Provide carbon source; shaping the carbon source so as to form a precursor powder having a preset shape; Carbonizing and activating the precursor powder to form pores to obtain a porous carbon skeleton having a plurality of pores; as well as A plurality of silicon particles are deposited in the plurality of pores of the porous carbon skeleton to obtain a silicon-carbon composite material; wherein the silicon-carbon composite material includes a plurality of silicon-based particles, the silicon-based particles include a porous carbon skeleton and a plurality of silicon particles, the range of the average aspect ratio AR of the plurality of silicon-based particles is 1.28≤AR≤10, the average aspect ratio AR of the plurality of silicon-based particles is AR=Lmax / Lmin, the average maximum length of the projections of the plurality of silicon-based particles is Lmax, and the average minimum length of the projections of the plurality of silicon-based particles is Lmin.

12. The method for preparing the silicon-carbon composite material according to claim 11, wherein: The ratio of the maximum length of the projection of the precursor powder to the minimum length of the projection of the precursor powder is between 1.28 and 10, and the proportion of the ratio is greater than or equal to 50%.

13. The method for preparing the silicon-carbon composite material according to claim 11, wherein: Shaping the carbon source so as to form a precursor powder having a preset shape includes: The carbon source is subjected to at least one process of hot pressing, rolling, extrusion, ball milling, and electrospinning to shape the carbon source so that the carbon source forms a precursor powder with a preset shape.

14. The method for preparing the silicon-carbon composite material according to claim 11, wherein: The precursor powder is a semi-cured resin. Before carbonizing and activating the precursor powder to form pores, the preparation method further includes: Precursor powder with a preset shape and a curing agent are dispersed in a solvent and cured at a temperature of 60° C. to 180° C.

15. The method for preparing the silicon-carbon composite material according to claim 11, wherein: The step of carbonizing and activating the precursor powder to form pores to obtain a porous carbon skeleton comprises: placing the precursor powder in an inert atmosphere and carbonizing it at a temperature of 400° C. to 1200° C. to obtain an intermediate carbon matrix; and The intermediate carbon matrix is ​​placed in a water vapor atmosphere, a carbon dioxide atmosphere, or a strong base at a temperature of 400° C. to 1200° C. for activation and pore formation, so as to obtain a porous carbon skeleton.

16. The method for preparing the silicon-carbon composite material according to claim 11, characterized in that: The step of depositing a plurality of silicon particles in a plurality of pores of the porous carbon skeleton comprises: A first mixed gas is introduced into the porous carbon skeleton and placed at a temperature of 400° C. to 800° C. to perform a first chemical vapor deposition to deposit multiple silicon particles in multiple pores of the porous carbon skeleton, wherein the first mixed gas includes silane and a first protective gas.

17. The method for preparing the silicon-carbon composite material according to any one of claims 11 to 16, characterized in that: The silicon-based particles further include a carbon coating layer, which is wrapped around the surface of the porous carbon skeleton; after depositing a plurality of silicon particles in the plurality of pores of the porous carbon skeleton, the preparation method further includes: A second mixed gas is introduced into the porous carbon skeleton having multiple silicon particles, and a second chemical vapor deposition is performed at a temperature of 400°C to 1000°C to form a carbon coating layer on the surface of the porous carbon skeleton. The second mixed gas includes an organic gas source and a second protective gas.

18. A negative electrode plate, characterized in that: The negative electrode plate comprises: a negative electrode current collector; and A negative electrode active layer, wherein the negative electrode active layer comprises the silicon-carbon composite material according to any one of claims 1 to 10 or the silicon-carbon composite material prepared by the method for preparing the silicon-carbon composite material according to any one of claims 11 to 17.

19. A battery, characterized in that: include: electrolyte; a positive electrode sheet, wherein the positive electrode sheet is at least partially immersed in the electrolyte; a diaphragm, the diaphragm being located on one side of the positive electrode plate and at least partially immersed in the electrolyte, and The negative electrode plate according to claim 18 is arranged on a side of the diaphragm away from the positive electrode plate and is at least partially immersed in the electrolyte.

20. An electronic device, characterized in that: include: Equipment body; as well as The battery according to claim 19 is used to power the device body.

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