Negative electrode active particle and preparation method therefor, battery and electronic device

Abstract

A negative electrode active particle (100) and a preparation method therefor, a battery (400) and an electronic device (500). The negative electrode active particle (100) comprises: a porous carbon matrix (10), the porous carbon matrix (10) having a plurality of pores (11), and the plurality of pores (11) comprising micropores (111), mesopores (112) and macropores (113), wherein, with respect to the plurality of pores (11), the number of the micropores (111) accounts for 5% to 35%, the number of the mesopores (112) accounts for 60% to 90%, and the number of the macropores (113) accounts for 4% to 6%; and silicon particles (20), the silicon particles (20) being distributed in the plurality of pores (11). The negative electrode active particle (100) has a lower expansion rate and a higher cycle capacity retention rate.

Description

Negative electrode active particles and preparation method thereof, battery and electronic equipment Technical Field

[0001] The present application relates to the field of battery materials, and specifically to a negative electrode active particle and a preparation method thereof, a battery and an electronic device. Background Art

[0002] Silicon has a high theoretical specific capacity (4200 mAh / g) and is the most promising negative electrode material for next-generation, high-energy-density batteries. However, silicon itself undergoes significant expansion during lithium insertion and repeatedly decomposes during charge and discharge to form a new solid electrolyte interphase (SEI) film. This accelerates electrolyte consumption, leading to a rapid decrease in the battery's cycle capacity retention rate and shortening the battery's service life. Summary of the Invention

[0003] The embodiments of the present application provide a negative electrode active particle having a lower expansion rate and a higher cycle capacity retention rate.

[0004] The first embodiment of the present application provides a negative electrode active particle, which includes:

[0005] A porous carbon matrix having a plurality of pores, wherein the plurality of pores include micropores, mesopores, and macropores, wherein the micropores account for 5% to 35%, the mesopores account for 60% to 90%, and the macropores account for 4% to 6% of the plurality of pores; and

[0006] Silicon particles are distributed in the plurality of pores.

[0007] A second embodiment of the present application provides a method for preparing negative electrode active particles, which includes:

[0008] Preparing a porous carbon matrix, wherein the porous carbon matrix has a plurality of pores, wherein the plurality of pores include micropores, mesopores, and macropores, wherein the number of the micropores accounts for 5% to 35%, the number of the mesopores accounts for 60% to 90%, and the number of the macropores accounts for 4% to 6%; and

[0009] A silicon source gas is introduced into the porous carbon matrix to deposit silicon particles in the pores of the porous carbon matrix.

[0010] A third embodiment of the present application provides a battery, comprising:

[0011] electrolyte;

[0012] a positive electrode sheet, wherein the positive electrode sheet is at least partially immersed in the electrolyte;

[0013] a diaphragm, the diaphragm being located on one side of the positive electrode plate and at least partially immersed in the electrolyte, and

[0014] A negative electrode plate, the negative electrode plate is arranged on the side of the separator away from the positive electrode plate and is at least partially immersed in the electrolyte, the negative electrode plate includes a negative electrode collector and a negative electrode active layer arranged on the surface of the negative electrode collector, the negative electrode active layer includes the negative electrode active particles described in the embodiment of the present application.

[0015] A fourth aspect of the present application provides an electronic device, comprising:

[0016] the device itself; and

[0017] The battery described in the embodiment of the present application is used to power the device body. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] 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.

[0019] FIG1 is a schematic diagram of the structure of negative electrode active particles according to an embodiment of the present application.

[0020] FIG2 is an enlarged view of the dotted frame I in FIG1 .

[0021] FIG3 is a schematic structural diagram of negative electrode active particles according to another embodiment of the present application.

[0022] FIG4 is a schematic flow chart of a method for preparing negative electrode active particles according to an embodiment of the present application.

[0023] FIG5 is a schematic diagram of the preparation process of a porous carbon matrix according to an embodiment of the present application.

[0024] FIG6 is a schematic flow chart of a method for preparing negative electrode active particles according to another embodiment of the present application.

[0025] FIG7 is a schematic structural diagram of a battery according to an embodiment of the present application.

[0026] FIG8 is a schematic cross-sectional view of a battery according to an embodiment of the present application along the AA direction in FIG7 .

[0027] FIG9 is a schematic structural diagram of a negative electrode plate according to an embodiment of the present application.

[0028] FIG10 is a schematic structural diagram of a positive electrode plate according to an embodiment of the present application.

[0029] FIG11 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

[0030] FIG12 is a schematic diagram of the exploded structure of an electronic device according to an embodiment of the present application.

[0031] FIG13 is a circuit block diagram of an electronic device according to an embodiment of the present application.

[0032] Explanation of the figure marks: 100-negative electrode active particles, 10-porous carbon matrix, 11-pores, 111-micropores, 112-mesopores, 113-macroporations, 20-silicon particles, 30-carbon coating, 400-battery, 410-positive electrode plate, 411-positive electrode current collector, 412-positive electrode active layer, 420-diaphragm, 430-negative electrode plate, 431-negative electrode current collector, 432-negative electrode active layer, 440-housing, 450-end cover assembly, 500-electronic device, 510-device body, 511-display, 513-middle frame, 515-housing, 516-memory, 517-processor, 518-camera module. DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] This embodiment provides a negative electrode active particle, including:

[0036] A porous carbon matrix having a plurality of pores, wherein the plurality of pores include micropores, mesopores, and macropores, wherein the micropores account for 5% to 35%, the mesopores account for 60% to 90%, and the macropores account for 4% to 6% of the plurality of pores; and

[0037] Silicon particles are distributed in the plurality of pores.

[0038] The pore volume of the porous carbon matrix is ​​in the range of 1.0 cm 3 / g to 2.0cm 3 / g.

[0039] The pore volume of the porous carbon matrix is ​​in the range of 1.0 cm 3 / g to 1.6m 3 / g.

[0040] The specific surface area S of the porous carbon matrix is ​​in the range of 500 m 2 / g≤S≤3000m 2 / g.

[0041] The particle size d1 of the silicon particles is in the range of 6 nm ≤ d1 ≤ 10 nm.

[0042] Wherein, the mass fraction of the silicon particles in the negative electrode active particles is in a range of 45% to 50%.

[0043] Wherein, in the porous carbon matrix, the mass fraction of oxygen atoms is less than or equal to 2%; and the range of the median particle size DV50 of the porous carbon matrix is ​​7 μm≤DV50≤9 μm.

[0044] The negative electrode active particles further include a carbon coating layer, which wraps around the surface of the porous carbon matrix and closes multiple pores of the porous carbon matrix; in the negative electrode active particles, the mass fraction of the carbon coating layer ranges from 10% to 15%.

[0045] Wherein, in the negative electrode active particles, the mass fraction of the carbon coating layer ranges from 10.5% to 14.5%.

[0046] This embodiment provides a method for preparing negative electrode active particles, comprising:

[0047] Preparing a porous carbon matrix, wherein the porous carbon matrix has a plurality of pores, wherein the plurality of pores include micropores, mesopores, and macropores, wherein the number of the micropores accounts for 5% to 35%, the number of the mesopores accounts for 60% to 90%, and the number of the macropores accounts for 4% to 6%; and

[0048] A silicon source gas is introduced into the porous carbon matrix to deposit silicon particles in the pores of the porous carbon matrix.

[0049] Wherein, the preparation of the porous carbon matrix comprises:

[0050] providing a carbon source and carbonizing the carbon source to obtain a first intermediate carbon matrix;

[0051] activating the first intermediate carbon matrix in a strong alkaline solution to form pores to obtain a second intermediate carbon matrix, wherein the molar concentration M of the strong alkaline solution is in the range of 5 mol / L≤M≤10 mol / L, and the mass ratio of the strong alkaline solution to the first intermediate carbon matrix is ​​in the range of 30% to 40%; and

[0052] The second intermediate carbon matrix is ​​calcined to obtain a porous carbon matrix.

[0053] Wherein, providing a carbon source and carbonizing the carbon source to obtain a first intermediate carbon matrix comprises:

[0054] A carbon source is provided, and the carbon source is carbonized in an inert atmosphere at a temperature of 600° C. to 800° C. for a carbonization time of 3 hours to 6 hours to obtain a first intermediate carbon matrix.

[0055] The step of activating the first intermediate carbon matrix in a strong alkaline solution to form pores comprises:

[0056] The first intermediate matrix is ​​mixed with a pore-forming agent and placed in a constant temperature device at 90° C. to 110° C. for activation and pore formation.

[0057] Wherein, after the activation and pore formation and before the calcination of the second intermediate carbon matrix, the preparation method further comprises:

[0058] The second intermediate carbon substrate is cleaned.

[0059] Wherein, the step of introducing a silicon source gas into the porous carbon matrix to deposit silicon particles in a plurality of pores of the porous carbon matrix comprises:

[0060] A first mixed gas is introduced into the porous carbon matrix, and a first chemical vapor deposition is performed at a temperature of 380°C to 450°C to deposit silicon particles in multiple pores of the porous carbon matrix, wherein the first mixed gas includes a silicon source gas and a first protective gas, and the volume fraction of the first protective gas in the first mixed gas ranges from 10% to 30%, and the flow rate of the first mixed gas ranges from 0.1m / s to 0.5m / s.

[0061] The step of introducing the first mixed gas into the porous carbon matrix and performing a first chemical vapor deposition at a temperature of 380° C. to 450° C. to deposit silicon particles in the pores of the porous carbon matrix includes:

[0062] The porous carbon matrix is ​​placed in a rotary furnace / fluidized bed, and a first mixed gas formed by mixing a silicon source gas and a first protective gas is introduced. The first chemical vapor deposition is performed at a temperature of 380°C to 450°C. The time of the first chemical vapor deposition is 1h to 3h to deposit silicon particles in multiple pores of the porous carbon matrix.

[0063] Wherein, the preparation method further comprises: forming a carbon coating layer on the surface of the porous carbon matrix having the silicon particles to close the plurality of pores;

[0064] The method of forming a carbon coating layer on the surface of the porous carbon matrix having the silicon particles to close the multiple pores includes: introducing a second mixed gas into the porous carbon matrix having silicon particles, and performing a second chemical vapor deposition at a temperature of 500°C to 700°C to form a carbon coating layer on the surface of the porous carbon matrix, wherein the second mixed gas includes an organic gas source and a second protective gas, and the flow rate of the second mixed gas ranges from 0.1m / s to 0.5m / s.

[0065] The step of introducing the second mixed gas into the porous carbon matrix having silicon particles and performing a second chemical vapor deposition at a temperature of 500° C. to 700° C. to form a carbon coating layer on the surface of the porous carbon matrix comprises:

[0066] The porous carbon matrix with silicon particles is placed in a rotary furnace / fluidized bed, and a second mixed gas consisting of an organic gas source and a second protective gas is introduced. The porous carbon matrix with silicon particles is soft-carbon coated at a temperature of 500°C to 700°C. The time of the second chemical vapor deposition is 1h to 4h.

[0067] This embodiment provides a battery, comprising:

[0068] electrolyte;

[0069] a positive electrode sheet, wherein the positive electrode sheet is at least partially immersed in the electrolyte;

[0070] a diaphragm, the diaphragm being located on one side of the positive electrode plate and at least partially immersed in the electrolyte, and

[0071] A negative electrode plate, the negative electrode plate is arranged on the side of the diaphragm away from the positive electrode plate and is at least partially immersed in the electrolyte, the negative electrode plate includes a negative electrode collector and a negative electrode active layer arranged on the surface of the negative electrode collector, the negative electrode active layer includes the negative electrode active particles provided in the above embodiment of the present application or the negative electrode active particles prepared by the method for preparing the negative electrode active particles provided in the above embodiment of the present application.

[0072] This embodiment provides an electronic device, including:

[0073] the device itself; and

[0074] The battery provided in the above embodiment of the present application is used to power the device body.

[0075] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0076] 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.

[0077] With the continuous development of lithium-ion battery technology, lithium-ion batteries have advantages over other types of batteries such as lead-acid and nickel-cadmium batteries, such as high specific capacity, no memory effect, high operating voltage, fast charging speed, wide operating temperature range, long cycle life, small size, and light weight. Currently, lithium-ion batteries are widely used in mobile phones, laptops, electric vehicles, energy storage cabinets and other fields, and their application range is becoming increasingly wider.

[0078] Silicon has a high theoretical specific capacity (4200 mAh / g) and is the most promising negative electrode material for next-generation, high-energy-density batteries. However, silicon itself undergoes significant expansion during lithium insertion and repeatedly decomposes during charge and discharge to form a new solid electrolyte interphase (SEI) film. This accelerates electrolyte consumption, leading to a rapid decrease in the battery's cycle capacity retention rate and shortening the battery's service life.

[0079] Please refer to Figures 1 and 2. The present application provides a negative electrode active particle 100, which includes: a porous carbon matrix 10 and silicon particles 20; the porous carbon matrix 10 has a plurality of pores 11, and the plurality of pores 11 include micropores 111, mesopores 112 and macropores 113. Among the plurality of pores 11, the number of the micropores 111 accounts for 5% to 35%, the number of the mesopores 112 accounts for 60% to 90%, and the number of the macropores 113 accounts for 4% to 6%; the silicon particles 20 are distributed in the plurality of pores 11.

[0080] The negative electrode active particles 100 of the present application can be used in batteries (such as lithium batteries) as negative electrode active materials for negative electrode sheets of the battery.

[0081] The term "micropores 111" herein refers to pores 11 with a size of less than 6 nm. The term "mesopores 112" refers to pores 11 with a size between 6 nm and 10 nm. The term "macropores 113" refers to pores 11 with a size greater than 10 nm.

[0082] 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.

[0083] Specifically, among the multiple pores 11 of the porous carbon skeleton, the proportion of the micropores 111 can be, but is not limited to, 5%, 10%, 15%, 20%, 25%, 30%, 35%, etc.

[0084] Specifically, in the multiple pores 11 of the porous carbon skeleton, the proportion of the mesopores 112 can be, but is not limited to, 60%, 65%, 70%, 75%, 80%, 85%, 90%, etc.

[0085] Specifically, among the multiple pores 11 of the porous carbon skeleton, the number of macropores 113 may be, but is not limited to, 4%, 4.3%, 4.5%, 4.8%, 5%, 5.3%, 5.5%, 5.8%, 6.0%, etc.

[0086] In one specific embodiment, among the multiple pores 11 of the porous carbon skeleton, the number of micropores 111 accounts for 30%, the number of mesopores 112 accounts for 65%, and the number of macropores 113 accounts for 5%. In another embodiment, among the multiple pores 11 of the porous carbon skeleton, the number of micropores 111 accounts for 5%, the number of mesopores 112 accounts for 90%, and the number of macropores 113 accounts for 5%.

[0087] The negative electrode active particles 100 of the present embodiment include a porous carbon matrix 10 and silicon particles 20. The porous carbon matrix 10 has a high proportion of mesopores 112 and a low proportion of micropores 111 in the multiple pores 11. By improving the distribution of the pores 11, the negative electrode active particles 100 are suitable for use in batteries. The high proportion of mesopores 112 provides more space for the negative electrode active particles 100 to buffer the expansion of the negative electrode active particles 100 during lithium insertion, thereby reducing the expansion rate of the negative electrode active particles 100. In addition, the high proportion of mesopores 112 in the porous carbon matrix 10 can also reduce the overflow of lithium-silicon alloy from the pores 11 when the negative electrode active particles 100 are inserted into lithium, reduce the side reactions of silicon particles 20 with the electrolyte outside the negative electrode active particles 100 during lithium removal, and increase the service life of the battery cell. Furthermore, the low proportion of macropores 113 can better prevent the negative electrode active particles 100 from breaking during the rolling process, thereby improving the yield rate of the negative electrode sheet.

[0088] In some embodiments, the pore volume of the porous carbon substrate 10 is in the range of 1.0 cm 3 / g to 2cm 3 / g.

[0089] Specifically, the pore volume of the porous carbon substrate 10 may be, but is not limited to, 1.0 cm 3 / g, 1.02cm 3 / g, 1.04cm 3 / g, 1.06cm 3 / g, 1.08cm 3 / g, 1.1cm 3 / g, 1.12cm 3 / g, 1.14cm 3 / g, 1.16cm 3 / g, 1.18cm 3 / g, 1.2cm 3 / g, 1.3cm 3 / g, 1.4cm 3 / g, 1.5cm 3 / g, 1.6cm 3 / g, 1.7cm 3 / g, 1.8cm 3 / g, 1.9cm 3 / g, 2cm 3 / g, etc.

[0090] In this embodiment, if the pore volume of the porous carbon matrix 10 is too small, the expansion rate of the negative electrode active particles 100 increases during the lithium insertion process of the negative electrode active particles 100, and the lithium-silicon alloy easily overflows from the pores 11 during lithium insertion. The silicon particles 20 formed during lithium removal are outside the negative electrode active particles 100, thereby increasing the side reactions with the electrolyte and greatly reducing the service life of the battery. If the pore volume of the porous carbon matrix 10 is too large, the mechanical strength of the negative electrode active particles 100 is reduced, making the negative electrode active particles 100 easily broken during the rolling process of preparing the negative electrode sheet. When the pore volume of the porous carbon matrix 10 is in the range of 1.0 cm 3 / g to 2cm 3 / g, the negative electrode active particles 100 can have a lower expansion rate and fewer side reactions during the lithium insertion process, while also having better mechanical strength and being less likely to break during the rolling process.

[0091] Furthermore, the pore volume of the porous carbon matrix 10 is in the range of 1.0 cm 3 / g to 1.6m 3 This allows the negative electrode active particles 100 to have a lower expansion rate and fewer side reactions during the lithium insertion process, while also allowing the negative electrode active particles 100 to have better mechanical strength and be less likely to break during the rolling process.

[0092] Furthermore, the pore volume of the porous carbon matrix 10 is in the range of 1.0 cm 3 / g to 1.2m 3 This allows the negative electrode active particles 100 to have a lower expansion rate and fewer side reactions during the lithium insertion process, while also allowing the negative electrode active particles 100 to have better mechanical strength and be less likely to break during the rolling process.

[0093] In some embodiments, the specific surface area S of the porous carbon matrix 10 is in the range of 500 m 2 / g≤S≤3000m 2 Specifically, the specific surface area of ​​the porous carbon substrate 10 may be, but is not limited to, 500 m 2 / g、600m 2 / g、800m 2 / g、1000m 2 / g、1500m 2 / g、2000m 2 / g、2500m 2 / g、3000m 2 / g、3500m 2 / g、4000m 2 / g, etc. If the specific surface area of ​​the porous carbon matrix 10 is too high, it means that there are a large number of pores 11 in the porous carbon matrix 10, which makes the content of silicon that can be deposited too high. The silicon particles 20 in the same pore 11 are easily connected to form a continuous silicon phase of larger particles, resulting in excessive expansion of the single silicon particle 20 during the lithium insertion process. If the specific surface area of ​​the porous carbon matrix 10 is too low, the content of deposited silicon is insufficient, which easily makes the specific capacity of the obtained negative electrode active particles 100 too low.

[0094] Furthermore, the specific surface area S of the porous carbon matrix 10 is in the range of 600 m 2 / g≤S≤2500m 2 This can better control the size of the silicon particles 20 in the negative electrode active particles 100, making the size of the silicon particles 20 in the negative electrode active particles 100 smaller, thereby having a better cycle capacity retention rate and making the negative electrode active particles 100 have a higher specific capacity.

[0095] Furthermore, the specific surface area S of the porous carbon matrix 10 is in the range of 800 m 2 / g≤S≤1800m 2 This can better control the size of the silicon particles 20 in the negative electrode active particles 100, making the size of the silicon particles 20 in the negative electrode active particles 100 smaller, thereby having a better cycle capacity retention rate and making the negative electrode active particles 100 have a higher specific capacity.

[0096] In some embodiments, the particle size d1 of the silicon particles 20 is in the range of 6 nm ≤ d1 ≤ 10 nm.

[0097] It should be noted that the particle size of the silicon particles 20 in the present application refers to the average particle size of the silicon particles 20 .

[0098] Specifically, the particle size d1 of the silicon particles 20 may be in the range of, but not limited to, 6 nm, 6.5 nm, 7 nm, 7.5 nm, 8 nm, 8.5 nm, 9 nm, 9.5 nm, 10 nm, etc.

[0099] In this embodiment, the smaller the particle size of the silicon particles 20, the more interfaces between silicon and carbon there are, the more lithium ion transfer interfaces there are, and the greater the impedance, causing the negative electrode active particles 100 to be overpolarized during use. The larger the particle size of the silicon particles 20, the less uniform the lithium insertion within the negative electrode active particles 100 becomes when lithium is inserted into the negative electrode active particles 100, making the negative electrode active particles 100 more susceptible to breakage and increasing their expansion rate. When the particle size of the silicon particles 20 is between 6 nm and 10 nm, the impedance to lithium ion migration is lowered, and the lithium insertion within the negative electrode active particles 100 is more uniform, resulting in a lower expansion rate and a lower likelihood of breakage.

[0100] Furthermore, the particle size d1 of the silicon particles 20 is in the range of 6 nm ≤ d1 ≤ 9 nm. This allows for lower resistance to lithium ion migration and more uniform lithium insertion within the negative electrode active particles 100 during lithium insertion, resulting in a lower expansion rate and less prone to breakage.

[0101] In some embodiments, the mass fraction of the silicon particles 20 in the negative electrode active particles 100 ranges from 45% to 50%.

[0102] Specifically, in the negative electrode active particles 100, the mass fraction of the silicon particles 20 ranges from 45%, 45.5%, 46%, 46.3%, 46.5%, 46.8%, 47%, 47.3%, 47.5%, 47.8%, 48%, 48.5%, 49%, 49.5%, 50%, etc.

[0103] In this embodiment, when the mass fraction of the silicon particles 20 in the negative electrode active particles 100 is too low, the initial efficiency of the negative electrode active particles 100 is reduced, the gram capacity of the positive electrode plate of the battery using the negative electrode active particles 100 is low, and the cost of the battery increases; when the mass fraction of the silicon particles 20 in the negative electrode active particles 100 is too high, the silicon particles 20 expand greatly during the lithium insertion process. During the expansion, the porous carbon matrix 10 is subjected to excessive stress, which causes serious damage to the porous carbon matrix 10. The negative electrode plate using the negative electrode active particles 100 is prone to pulverization, thereby causing the negative electrode active particles 100 to fail and reducing the service life of the battery. When the mass fraction of the silicon particles 20 in the negative electrode active particles 100 is in the range of 45% to 50%, the battery using the negative electrode active particles 100 can have a higher initial efficiency, the gram capacity of the positive electrode plate of the battery can be better utilized, and the cost of the battery can be reduced. At the same time, the negative electrode active particles 100 can have a lower expansion when lithium is inserted, and the negative electrode active particles 100 are not easy to break during the lithium insertion process, which reduces the probability of pulverization of the negative electrode plate and improves the service life of the battery.

[0104] Furthermore, the mass fraction of the silicon particles 20 in the negative electrode active particles 100 ranges from 46% to 48%. This allows batteries using the negative electrode active particles 100 to achieve higher initial efficiency, better utilize the specific capacity of the battery's positive electrode sheet, and reduce battery costs. Furthermore, the negative electrode active particles 100 can exhibit lower expansion during lithium insertion, making them less susceptible to breakage during the lithium insertion process, reducing the probability of negative electrode sheet pulverization and extending the battery's service life.

[0105] In some embodiments, the mass fraction of oxygen atoms in the porous carbon matrix 10 is less than or equal to 2%. Specifically, the mass fraction of oxygen atoms in the porous carbon matrix 10 may be, but is not limited to, less than or equal to 2%, less than or equal to 1.5%, less than or equal to 1.3%, less than or equal to 1%, less than or equal to 0.8%, etc. In this embodiment, the porous carbon matrix 10 has a lower oxygen atom content, which reduces the content of heteroatoms in the porous carbon matrix 10, making the porous carbon matrix 10 have a higher purity. As a result, when the negative electrode active particles 100 are used in a battery, the battery has a higher initial efficiency.

[0106] Optionally, the median particle size DV50 of the porous carbon matrix 10 is in the range of 7 μm≤DV50≤9 μm.

[0107] Specifically, the median particle size DV50 of the porous carbon matrix 10 may be, but is not limited to, 7 μm, 7.2 μm, 7.4 μm, 7.6 μm, 7.8 μm, 8.2 μm, 8.4 μm, 8.6 μm, 8.8 μm, 9 μm, etc.

[0108] In this embodiment, if the median particle size DV50 of the porous carbon matrix 10 is too small, the yield of the negative electrode active particles 100 is low, and the preparation cost of the negative electrode active particles 100 is increased; if the median particle size DV50 of the porous carbon matrix 10 is too large, the impedance of the diffusion of lithium ions in the negative electrode active particles 100 is too large, and the rate performance of the battery using the negative electrode active particles 100 is reduced; in addition, if the median particle size DV50 of the porous carbon matrix 10 is too large, when DV100 is larger than the size of the coating machine roller gap, scratches may be generated when the slurry prepared from the negative electrode active particles 100 is coated to prepare the negative electrode sheet, thereby reducing the production yield of the negative electrode sheet. When the median particle size DV50 of the porous carbon matrix 10 is in the range of 7μm≤DV50≤9μm, the negative electrode active particles 100 can have a lower preparation cost, the impedance of lithium ion diffusion in the negative electrode active particles 100 is low, and the battery using the negative electrode active particles 100 has good rate performance; and the negative electrode sheet prepared using the negative electrode active particles 100 is not prone to scratches during production.

[0109] Referring to FIG. 3 , in some embodiments, the negative electrode active particles 100 further include a carbon coating layer 30 . The carbon coating layer 30 wraps around the surface of the porous carbon matrix 10 and closes the plurality of pores 11 of the porous carbon matrix 10 .

[0110] It can be understood that the carbon coating layer 30 is used to wrap the porous carbon matrix 10 and wrap the silicon particles 20 in the multiple pores 11 of the porous carbon matrix 10 to minimize the direct exposure of the silicon particles 20 to the negative electrode active 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, which will reduce the specific capacity of the negative electrode active particles 100 and cause the cycle capacity retention rate of the negative electrode active particles 100 to continue to decrease with the increase in the number of cycles. In this embodiment, the negative electrode active particles 100 have a carbon coating layer 30. When used in a battery, it can prevent the silicon particles 20 from directly contacting the electrolyte, thereby avoiding more side reactions, so that the negative electrode active particles 100 have a higher cycle capacity retention rate, especially high temperature cycle performance.

[0111] Optionally, in the negative electrode active particles 100 , the mass fraction of the carbon coating layer 30 is in a range of 10% to 15%.

[0112] Specifically, in the negative electrode active particles 100 , the mass fraction of the carbon coating layer 30 may be, but is not limited to, 10%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5%, 15%, etc.

[0113] In this embodiment, when the mass fraction of the carbon coating layer 30 in the negative electrode active particles 100 is too low, the carbon coating layer 30 does not completely cover the pores 11 of the porous carbon matrix 10, which can easily expose some silicon particles 20 and increase side reactions between the silicon particles 20 and the electrolyte. In addition, the increased specific surface area of ​​the negative electrode active particles 100 reduces the initial efficiency of the battery using the negative electrode active particles 100. During homogenization, the contact area between the negative electrode active particles 100 and water increases, which can easily lead to gas generation. When the mass fraction of the carbon coating layer 30 in the negative electrode active particles 100 is too high, the initial efficiency of the battery using the negative electrode active particles 100 is also reduced, the impedance of lithium ion diffusion is increased, and the battery's kinetic performance is reduced. In addition, a high mass fraction of the carbon coating layer 30 can also reduce the specific capacity of the negative electrode active particles 100. When the mass fraction of the carbon coating layer 30 in the negative electrode active particles 100 is in the range of 10% to 15%, the battery using the negative electrode active particles 100 can have a higher initial efficiency, is less likely to produce gas during the homogenization process, reduces the side reaction between the negative electrode active particles 100 and the electrolyte, improves the cycle capacity retention rate of the battery using the negative electrode active particles 100, and at the same time has lower impedance and better kinetic performance.

[0114] Furthermore, the mass fraction of the carbon coating layer 30 in the negative electrode active particles 100 ranges from 10.5% to 14.5%. This allows batteries using the negative electrode active particles 100 to have higher initial efficiency, less likely to generate gas during homogenization, reduce side reactions between the negative electrode active particles 100 and the electrolyte, and improve the cycle capacity retention rate of batteries using the negative electrode active particles 100, while also having lower impedance and better kinetic performance.

[0115] The negative electrode active particles 100 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 negative electrode active particles 100 of the present application and should not be understood as limiting the negative electrode active particles 100 provided in the embodiments of the present application.

[0116] Referring to FIG. 4 , the present embodiment further provides a method for preparing negative electrode active particles 100 , which includes:

[0117] S201, preparing a porous carbon matrix 10, wherein the porous carbon matrix 10 has a plurality of pores 11, wherein the plurality of pores 11 include micropores 111, mesopores 112, and macropores 113, wherein among the plurality of pores 11, the number of the micropores 111 accounts for 5% to 35%, the number of the mesopores 112 accounts for 60% to 90%, and the number of the macropores 113 accounts for 4% to 6%; and

[0118] For detailed description of other aspects of the porous carbon substrate 10 , please refer to the description of the corresponding parts of the above embodiments.

[0119] S202 , introducing a silicon source gas into the porous carbon matrix 10 to deposit silicon particles 20 in the plurality of pores 11 of the porous carbon matrix 10 .

[0120] For detailed description of other aspects of the silicon particles 20 , please refer to the description of the corresponding parts of the above embodiments.

[0121] The negative electrode active particles 100 prepared by the method for preparing the negative electrode active particles 100 of the embodiment of the present application include a porous carbon matrix 10 and silicon particles 20. The porous carbon matrix 10 has a plurality of pores 11, which have a relatively high proportion of mesopores 112 and a relatively low proportion of micropores 111. By improving the distribution of the pores 11, the negative electrode active particles 100 can be used in batteries. The relatively high proportion of mesopores 112 provides the negative electrode active particles 100 with more space during the lithium insertion process to buffer the expansion of the negative electrode active particles 100 during lithium insertion, thereby reducing the expansion rate of the negative electrode active particles 100. In addition, the relatively high proportion of mesopores 112 in the porous carbon matrix 10 can also reduce the overflow of lithium-silicon alloy from the pores 11 when the negative electrode active particles 100 are inserted with lithium, reduce the side reactions of the silicon particles 20 with the electrolyte outside the negative electrode active particles 100 during lithium removal, and increase the service life of the battery cell. Furthermore, a lower proportion of macropores 113 can better prevent the negative electrode active particles 100 from breaking during the rolling process, thereby improving the preparation yield of the negative electrode sheet.

[0122] Referring to FIG. 5 , in some embodiments, the preparation of the porous carbon substrate 10 includes:

[0123] S2011, providing a carbon source and carbonizing the carbon source to obtain a first intermediate carbon matrix;

[0124] Optionally, a carbon source is provided and carbonized in an inert atmosphere at a temperature of 600°C to 800°C for a period of 3 to 6 hours to obtain a first intermediate carbon matrix. In this embodiment, carbonization at a higher temperature and for a longer time can reduce the amount of heteroatoms in the obtained first intermediate carbon matrix while enhancing the carbon structure stability of the obtained first intermediate carbon matrix, thereby achieving the optimal combination of structural stability and initial efficiency of the final negative electrode active particles 100.

[0125] Alternatively, the carbon source may be a resin-based carbon source. The resin-based carbon source may include, but is not limited to, at least one of a phenolic resin-based carbon source and an epoxy resin-based carbon source. Using a resin-based carbon source to prepare the porous carbon substrate 10 can make the resulting porous carbon substrate 10 more structurally stable and have higher pressure resistance.

[0126] Optionally, the carbonization temperature may be, but is not limited to, 600°C, 620°C, 640°C, 660°C, 680°C, 700°C, 720°C, 740°C, 760°C, 780°C, 800°C, etc. If the carbonization temperature is too low, the carbon source cannot be well carbonized, resulting in too much heteroatom content (such as oxygen atoms) in the porous carbon matrix 10, thereby reducing the initial efficiency of the battery using the negative electrode active particles 100; if the carbonization temperature is too high, the gasification reaction during carbonization is intense, which easily leads to a loose structure and poor structural stability of the porous carbon matrix 10. The porous carbon matrix 10 has poor pressure resistance, and the negative electrode active particles 100 are easily broken during the rolling process of preparing the negative electrode sheet using the negative electrode active particles 100.

[0127] Optionally, the carbonization time may be, but is not limited to, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h, etc. If the carbonization time is too short, the carbon source cannot be well carbonized, resulting in too much heteroatom (e.g., oxygen atom) content in the porous carbon matrix 10, thereby reducing the initial efficiency of the battery using the negative electrode active particles 100; if the carbonization time is too long, the structure of the porous carbon matrix 10 obtained is likely to be loose, the structural stability is poor, and the pressure resistance of the porous carbon matrix 10 obtained is poor. In the process of rolling the negative electrode sheet prepared using the negative electrode active particles 100, the negative electrode active particles 100 are easily broken.

[0128] Optionally, the inert atmosphere may be nitrogen, argon, etc. The inert gas is used to isolate oxygen and protect the prepared first intermediate carbon matrix.

[0129] S2012, activating the first intermediate carbon matrix in a strong alkaline solution to form pores to obtain a second intermediate carbon matrix, wherein the molar concentration M of the strong alkaline solution is in the range of 5 mol / L≤M≤10 mol / L, and the mass ratio of the strong alkaline solution to the first intermediate carbon matrix is ​​in the range of 30% to 40%; and

[0130] Optionally, the first intermediate matrix is ​​mixed with a pore-forming agent (i.e., a strong alkaline solution) and placed in a constant temperature device at 90°C to 110°C (specifically, 90°C, 95°C, 100°C, 105°C, 110°C, etc.) for activation and pore formation.

[0131] 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.

[0132] Optionally, the molar concentration M of the strong alkali solution can be, but is not limited to, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, 10 mol / L, etc. If the molar concentration of the strong alkali solution is too low, the pores 11 of the porous carbon matrix 10 (or the second intermediate carbon matrix) finally obtained are easily unevenly distributed, the porosity 11 rate is low, and the number of micropores 111 in the porous carbon matrix 10 obtained is large, and the number of mesopores 112 is small, making it difficult to obtain a porous carbon matrix 10 with a high proportion of mesopores 112; if the molar concentration of the strong alkali solution is too high, it is easy to make the number of mesopores 112 and macropores 113 in the porous carbon matrix 10 obtained too high, the number of micropores 111 is insufficient, and the structure of the porous carbon matrix 10 is loose and the pressure resistance is poor.

[0133] Optionally, the mass ratio of the strong base to the first intermediate carbon matrix in the strong base solution can be, but is not limited to, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, etc. If the mass ratio of the strong base to the first intermediate carbon matrix in the strong base solution is too low, the pores 11 of the porous carbon matrix 10 (or the second intermediate carbon matrix) finally obtained are easily unevenly distributed, the porosity 11 rate is low, and the number of micropores 111 in the porous carbon matrix 10 obtained is large, and the number of mesopores 112 is small, making it difficult to obtain a porous carbon matrix 10 with a high proportion of mesopores 112; if the mass ratio of the strong base to the first intermediate carbon matrix in the strong base solution is too high, it is easy to make the number of mesopores 112 and macropores 113 in the porous carbon matrix 10 obtained too high, the number of micropores 111 is insufficient, and the structure of the porous carbon matrix 10 is loose and the pressure resistance is poor.

[0134] Optionally, the activation pore-forming time (i.e., the corrosion time of the strong alkali) can be 2h to 4h. Specifically, the activation pore-forming time can be, but is not limited to, 2h, 2.5h, 3h, 3.5h, 4h, etc. If the activation pore-forming time is too short, the pores 11 of the porous carbon matrix 10 (or the second intermediate carbon matrix) finally obtained are easily unevenly distributed, the porosity 11 rate is low, and the number of micropores 111 in the porous carbon matrix 10 obtained is large, and the number of mesopores 112 is small, making it difficult to obtain a porous carbon matrix 10 with a high proportion of mesopores 112. If the activation pore-forming time is too long, it is easy to make the number of mesopores 112 and macropores 113 in the porous carbon matrix 10 obtained too high, the number of micropores 111 is insufficient, and the structure of the porous carbon matrix 10 is loose and the pressure resistance is poor.

[0135] In some embodiments, after the activation and pore creation and before the calcining of the second intermediate carbon matrix, the preparation method further comprises: washing the second intermediate carbon matrix.

[0136] Optionally, the cleaning includes first acid washing, then water washing until neutral, and drying. Acid washing can dissolve a large amount of impurities and heteroatoms generated during the pore formation process and can also neutralize residual strong alkali.

[0137] S2013, calcining the second intermediate carbon matrix to obtain a porous carbon matrix 10.

[0138] Optionally, the second intermediate carbon matrix is ​​placed in a tube furnace and calcined at a temperature of 400° C. to 600° C. under an inert atmosphere (e.g., a nitrogen atmosphere or an argon atmosphere) to obtain a porous carbon matrix 10. By calcining the second intermediate carbon matrix at a high temperature, the content of heteroatoms in the obtained porous carbon matrix 10 can be further reduced, thereby improving the initial efficiency of a battery using the porous carbon matrix 10.

[0139] Optionally, the calcination temperature may be, but is not limited to, 400°C, 420°C, 440°C, 460°C, 480°C, 500°C, 520°C, 540°C, 560°C, 580°C, 600°C, etc. If the calcination temperature is too low, the heteroatoms in the second intermediate carbon matrix cannot be removed well, resulting in a high heteroatom content in the porous carbon matrix 10. If the calcination temperature is too high, the structure of the porous carbon matrix 10 obtained will be loose, and the pressure resistance of the porous carbon matrix 10 will deteriorate.

[0140] For the relevant technical features of the porous carbon matrix 10 obtained in the embodiment of the present application, please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0141] In some embodiments, in S202, the silicon source gas is introduced into the porous carbon matrix 10 to deposit silicon particles 20 in multiple pores 11 of the porous carbon matrix 10, including: introducing a first mixed gas into the porous carbon matrix 10, and performing a first chemical vapor deposition at a temperature of 380°C to 450°C to deposit silicon particles 20 in multiple pores 11 of the porous carbon matrix 10, wherein the first mixed gas includes a silicon source gas and a first protective gas, and the volume fraction of the first protective gas in the first mixed gas ranges from 10% to 30%.

[0142] Regarding the relevant technical features of the silicon particles 20, please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0143] Optionally, the porous carbon matrix 10 is placed in a rotary furnace / fluidized bed, and a first mixed gas formed by mixing a silicon source gas and a first protective gas is introduced, and a first chemical vapor deposition is performed at a temperature of 380°C to 450°C. The time of the first chemical vapor deposition is 1h to 3h, so as to deposit silicon particles 20 in multiple pores 11 of the porous carbon matrix 10.

[0144] Optionally, the silicon source gas may include but is not limited to at least one of monosilane, disilane, dichlorosilane, trichlorosilane, and the like.

[0145] Optionally, the first protective gas may be, but is not limited to, at least one of nitrogen, argon, and the like.

[0146] Optionally, the volume fraction of the first shielding gas in the first mixed gas may be, but is not limited to, 10%, 15%, 20%, 25%, 30%, etc. If the proportion of the first shielding gas in the first mixed gas is too low, the risk of silicon particle 20 deposition production increases. If the proportion of the first shielding gas in the first mixed gas is too high, the efficiency of the first chemical vapor deposition process decreases.

[0147] It is understood that the volume fraction of the silicon source gas in the first mixed gas ranges from 70% to 90%. Specifically, the volume fraction of the silicon source gas in the first mixed gas is 70%, 75%, 80%, 85%, or 90%. If the proportion of the silicon source gas in the first mixed gas is too high, the risk of silicon particle 20 deposition increases. If the proportion of the silicon source gas in the first mixed gas is too low, the efficiency of the first chemical vapor deposition is reduced.

[0148] Optionally, the temperature of the first chemical vapor deposition may be, but is not limited to, 380° C., 390° C., 400° C., 410° C., 420° C., 430° C., 440° C., 450° C., etc. If the temperature of the first chemical vapor deposition is too low, the silicon source gas is difficult to be completely reduced, resulting in low productivity. 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 imparting anisotropic expansion to the silicon particles 20, increasing the expansion rate of the silicon particles 20 during lithium insertion, and easily generating chemically inert silicon carbide, thereby reducing the energy density of the negative electrode active particles 100.

[0149] Optionally, the time for the first chemical vapor deposition can be, but is not limited to, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc. If the time for 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 matrix 10, which easily leads to uneven deposition of the silicon particles 20 in the porous carbon matrix 10; if the time for the first chemical vapor deposition is too long, the silicon particles 20 are easily deposited on the surface of the porous carbon matrix 10, so that the silicon particles 20 on the surface of the porous carbon matrix 10 have no buffer space when lithium is inserted, thereby increasing the expansion rate of the negative electrode active particles 100 and reducing the service life of the negative electrode active particles 100.

[0150] Optionally, in this embodiment, the deposition amount of the silicon particles 20 is controlled so that the silicon particles 20 account for 46% to 48% of the mass of the negative electrode active particles 100. In this embodiment, when the mass fraction of the silicon particles 20 in the negative electrode active particles 100 is too low, the initial efficiency of the negative electrode active particles 100 is reduced, the gram capacity of the positive electrode plate of the battery using the negative electrode active particles 100 is low, and the cost of the battery increases; when the mass fraction of the silicon particles 20 in the negative electrode active particles 100 is too high, the silicon particles 20 expand greatly during the lithium insertion process. During the expansion, the porous carbon matrix 10 is subjected to excessive stress, resulting in serious damage to the porous carbon matrix 10. The negative electrode plate using the negative electrode active particles 100 is prone to pulverization, thereby causing the negative electrode active particles 100 to fail and reducing the service life of the battery. When the mass fraction of the silicon particles 20 in the negative electrode active particles 100 is in the range of 45% to 50%, the battery using the negative electrode active particles 100 can have a higher initial efficiency, the gram capacity of the positive electrode plate of the battery can be better utilized, and the cost of the battery can be reduced. At the same time, the negative electrode active particles 100 can have a lower expansion when lithium is inserted, and the negative electrode active particles 100 are not easy to break during the lithium insertion process, which reduces the probability of pulverization of the negative electrode plate and improves the service life of the battery.

[0151] In some embodiments, when the first chemical vapor deposition is carried out in a fluidized bed, the flow rate of the first mixed gas ranges from 0.1 m / s to 0.5 m / s. Specifically, the flow rate of the first mixed gas can be, but is not limited to, 0.1 m / s, 0.15 m / s, 0.2 m / s, 0.25 m / s, 0.3 m / s, 0.35 m / s, 0.4 m / s, 0.45 m / s, 0.5 m / s, etc. If the flow rate of the first mixed gas is too small, the deposition rate of the silicon particles 20 is reduced, and the production capacity of the negative electrode active particles 100 is reduced; if the flow rate of the first mixed gas is too large, the uniformity of the silicon deposition is reduced. In addition, silicon is easily deposited on the surface of the porous carbon matrix 10, thereby increasing the expansion rate of the negative electrode active particles 100 and reducing the cycle capacity retention rate of the negative electrode active particles 100. When the flow rate of the first mixed gas ranges from 0.1 m / s to 0.5 m / s, the silicon particles 20 can be more evenly deposited in the multiple pores 11 of the porous carbon matrix 10, and the pores 11 of the porous carbon matrix 10 can be better blocked, reducing the possibility of silicon overflowing from the porous carbon matrix 10 when lithium is embedded, thereby reducing the side reactions of the battery using the negative electrode active particles 100.

[0152] Referring to FIG. 6 , the present embodiment further provides a method for preparing negative electrode active particles 100 , which includes:

[0153] S301, preparing a porous carbon substrate 10, wherein the porous carbon substrate 10 has a plurality of pores 11, wherein the plurality of pores 11 include micropores 111, mesopores 112, and macropores 113, wherein among the plurality of pores 11, the number of the micropores 111 accounts for 5% to 35%, the number of the mesopores 112 accounts for 60% to 90%, and the number of the macropores 113 accounts for 4% to 6%; and

[0154] S302 , introducing a silicon source gas into the porous carbon matrix 10 to deposit silicon particles 20 in the plurality of pores 11 of the porous carbon matrix 10 .

[0155] For a detailed description of S301 and S302 , please refer to the description of the corresponding parts of the above embodiment, which will not be repeated here.

[0156] S303 , forming a carbon coating layer 30 on the surface of the porous carbon matrix 10 having the silicon particles 20 to close the plurality of pores 11 .

[0157] Optionally, the carbon coating layer 30 is formed on the surface of the porous carbon matrix 10 having the silicon particles 20 to close the multiple pores 11, including: introducing a second mixed gas into the porous carbon matrix 10 having the silicon particles 20, and performing a second chemical vapor deposition at a temperature of 500°C to 700°C to form a carbon coating layer 30 on the surface of the porous carbon matrix 10, wherein the second mixed gas includes an organic gas source and a second protective gas.

[0158] Optionally, the porous carbon matrix 10 having silicon particles 20 is placed in a rotary furnace / fluidized bed, and a second mixed gas consisting of an organic gas source and a second protective gas is introduced. The porous carbon matrix 10 having silicon particles 20 is soft-carbon coated at a temperature of 500°C to 700°C, and the time for the second chemical vapor deposition is 1h to 4h.

[0159] Optionally, the organic gas source may include but is not limited to at least one of acetylene, ethylene, methane, etc.

[0160] Optionally, the second protective gas may be, but is not limited to, at least one of nitrogen, argon, and the like.

[0161] Optionally, the temperature of the second chemical vapor deposition may be, but is not limited to, 500° C., 550° C., 600° C., 650° C., 700° C., etc. If the temperature of the second chemical vapor deposition is too low, the organic gas source is difficult to reduce; 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 negative electrode active particles 100.

[0162] Optionally, the second chemical vapor deposition time can be, but is not limited to, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 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 matrix 10, leaving some silicon particles 20 exposed, thereby increasing the side reaction between the negative electrode active particles 100 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 negative electrode active particles 100.

[0163] In some embodiments, when the second chemical vapor deposition is performed in a fluidized bed, the flow rate of the second mixed gas ranges from 0.1 m / s to 0.5 m / s. Specifically, the flow rate of the second mixed gas may be, but is not limited to, 0.1 m / s, 0.15 m / s, 0.2 m / s, 0.25 m / s, 0.3 m / s, 0.35 m / s, 0.4 m / s, 0.45 m / s, 0.5 m / s, etc. Lowering the flow rate of the second mixed gas can reduce the deposition rate of the carbon coating layer 30, making the deposition of the carbon coating layer 30 more uniform, better blocking the pores 11 of the porous carbon matrix 10, increasing the protection of the carbon coating layer 30 on the silicon particles 20, and better inhibiting the expansion of the silicon particles 20 when lithium is inserted, which is beneficial to the cycle performance of the negative electrode active particles 100; however, if the flow rate of the second mixed gas is too small, the deposition rate of the carbon coating layer 30 is reduced, and the production capacity of the negative electrode active particles 100 is reduced; if the flow rate of the second mixed gas is too high, the uniformity of the deposition of the carbon coating layer 30 is reduced, which is not conducive to blocking the pores 11 of the porous carbon matrix 10, thereby making it easy for the silicon particles 20 to overflow when the negative electrode active particles 100 are inserted with lithium, thereby reducing the cycle performance of the negative electrode active particles 100. When the flow rate of the second mixed gas is in the range of 0.1m / s to 0.5m / s, the negative electrode active particles 100 can have a higher output, and the carbon coating layer 30 can be deposited more evenly, better blocking the multiple pores 11 of the porous carbon matrix 10, reducing the overflow of silicon particles 20 when the negative electrode active particles 100 are embedded with lithium, and increasing the cycle performance of the negative electrode active particles 100.

[0164] Furthermore, when the second chemical vapor deposition is performed in a fluidized bed, the flow rate of the second mixed gas ranges from 0.1 m / s to 0.3 m / s. This allows for a higher yield of the negative electrode active particles 100, more uniform deposition of the carbon coating layer 30, better blocking the pores 11 of the porous carbon matrix 10, reducing the overflow of the silicon particles 20 during lithium insertion into the negative electrode active particles 100, and improving the cycling performance of the negative electrode active particles 100.

[0165] In some embodiments, the flow rate of the second mixed gas may be faster at first and then slowed down during deposition, thereby both creating and blocking the pores 11 of the porous carbon matrix 10. For example, the second mixed gas may be first deposited at a flow rate of 0.4 m / s and then at a flow rate of 0.15 m / s.

[0166] Optionally, in this embodiment, the deposition amount of the carbon coating layer 30 is controlled so that the carbon coating layer 30 accounts for 10% to 15% by mass of the negative electrode active particles 100. In this embodiment, when the mass fraction of the carbon coating layer 30 in the negative electrode active particles 100 is too low, the carbon coating layer 30 does not completely cover the pores 11 of the porous carbon matrix 10, which easily exposes some silicon particles 20 and increases the side reaction between the silicon particles 20 and the electrolyte. In addition, the increased specific surface area of ​​the negative electrode active particles 100 reduces the initial efficiency of the battery using the negative electrode active particles 100, and increases the contact area between the negative electrode active particles 100 and water during homogenization, which easily generates gas. When the mass fraction of the carbon coating layer 30 in the negative electrode active particles 100 is too high, the initial efficiency of the battery using the negative electrode active particles 100 will be reduced, the impedance of lithium ion diffusion will be increased, and the kinetic performance of the battery will be reduced. In addition, when the mass fraction of the carbon coating layer 30 is too high, the specific capacity of the negative electrode active particles 100 will be reduced. When the mass fraction of the carbon coating layer 30 in the negative electrode active particles 100 is in the range of 10% to 15%, the battery using the negative electrode active particles 100 can have a higher initial efficiency, is less likely to produce gas during the homogenization process, reduces the side reaction between the negative electrode active particles 100 and the electrolyte, and improves the cycle capacity retention rate of the battery using the negative electrode active particles 100, while also having lower impedance and better kinetic performance.

[0167] The negative electrode active particles 100 of the present application are further described below through specific examples.

[0168] Example 1

[0169] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0170] 1) carbonizing a phenolic resin-based carbon source in an inert atmosphere at 650° C. for 4 hours to obtain a first intermediate carbon matrix;

[0171] 2) placing the first intermediate carbon matrix in a sodium hydroxide aqueous solution having a molar concentration of 6 mol / L at a temperature of 100° C. for etching for 2 hours to obtain a second intermediate carbon matrix, wherein the mass ratio of the sodium hydroxide in the sodium hydroxide aqueous solution to the mass ratio of the first intermediate carbon matrix is ​​30%;

[0172] 3) The second intermediate substrate was placed in a tube furnace and calcined at 500° C. under a nitrogen atmosphere to obtain a porous carbon substrate 10. The obtained porous carbon substrate 10 had a particle size of 7.5 μm. The pore volume, specific surface area, and pore size distribution of the porous carbon substrate 10 of this embodiment are shown in Table 1 below.

[0173] 4) placing the porous carbon substrate 10 in a rotary kiln and performing a first chemical vapor deposition at 400° C. for 2 h using a first mixed gas of monosilane and nitrogen to deposit silicon particles 20 in the plurality of pores 11 of the porous carbon substrate 10, wherein the volume fraction of nitrogen in the first mixed gas is in the range of 20%, and the particle size of the silicon particles 20 in the porous carbon substrate 10 is 7 nm;

[0174] 5) The porous carbon substrate 10 with the silicon particles 20 deposited thereon is placed in a rotary kiln, and a second mixed gas of acetylene and nitrogen is introduced thereinto. A second chemical vapor deposition is performed at a temperature of 550° C. for 3 hours to form a carbon coating layer 30 .

[0175] In the negative electrode active particles 100 prepared in this embodiment, the mass fraction of the porous carbon skeleton is 43%, the mass fraction of the silicon particles 20 is 48%, and the mass fraction of the carbon coating layer 30 is 9%.

[0176] Example 2

[0177] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0178] 1) carbonizing a phenolic resin-based carbon source in an inert atmosphere at 650° C. for 4 hours to obtain a first intermediate carbon matrix;

[0179] 2) placing the first intermediate carbon matrix in a sodium hydroxide aqueous solution having a molar concentration of 6 mol / L at a temperature of 100° C. for etching for 2 hours to obtain a second intermediate carbon matrix, wherein the mass ratio of the sodium hydroxide in the sodium hydroxide aqueous solution to the mass ratio of the first intermediate carbon matrix is ​​35%;

[0180] 3) The second intermediate substrate was placed in a tube furnace and calcined at 500° C. under a nitrogen atmosphere to obtain a porous carbon substrate 10. The obtained porous carbon substrate 10 had a particle size of 7.5 μm. The pore volume, specific surface area, and pore size distribution of the porous carbon substrate 10 of this embodiment are shown in Table 1 below.

[0181] 4) placing the porous carbon substrate 10 in a rotary kiln and performing a first chemical vapor deposition at 400° C. for 2 h using a first mixed gas of monosilane and nitrogen to deposit silicon particles 20 in the plurality of pores 11 of the porous carbon substrate 10, wherein the volume fraction of nitrogen in the first mixed gas is in the range of 20%, and the particle size of the silicon particles 20 in the porous carbon substrate 10 is 7 nm;

[0182] 5) The porous carbon substrate 10 with the silicon particles 20 deposited thereon is placed in a rotary kiln, and a second mixed gas of acetylene and nitrogen is introduced thereinto. A second chemical vapor deposition is performed at a temperature of 550° C. for 3.5 hours to form a carbon coating layer 30 .

[0183] In the negative electrode active particles 100 prepared in this embodiment, the mass fraction of the porous carbon skeleton is 40%, the mass fraction of the silicon particles 20 is 48%, and the mass fraction of the carbon coating layer 30 is 12%.

[0184] Example 3

[0185] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0186] 1) carbonizing a phenolic resin-based carbon source in an inert atmosphere at 650° C. for 4 hours to obtain a first intermediate carbon matrix;

[0187] 2) placing the first intermediate carbon matrix in a sodium hydroxide aqueous solution at a temperature of 100° C. and a molar concentration of 6 mol / L for etching for 2 hours to obtain a second intermediate carbon matrix, wherein the mass ratio of the sodium hydroxide in the sodium hydroxide aqueous solution to the mass ratio of the first intermediate carbon matrix is ​​40%;

[0188] 3) The second intermediate substrate was placed in a tube furnace and calcined at 500° C. under a nitrogen atmosphere to obtain a porous carbon substrate 10. The obtained porous carbon substrate 10 had a particle size of 7.5 μm. The pore volume, specific surface area, and pore size distribution of the porous carbon substrate 10 of this embodiment are shown in Table 1 below.

[0189] 4) placing the porous carbon substrate 10 in a rotary kiln and performing a first chemical vapor deposition at 400° C. for 2 h using a first mixed gas of monosilane and nitrogen to deposit silicon particles 20 in the plurality of pores 11 of the porous carbon substrate 10, wherein the volume fraction of nitrogen in the first mixed gas is in the range of 20%, and the particle size of the silicon particles 20 in the porous carbon substrate 10 is 7 nm;

[0190] 5) The porous carbon substrate 10 with the silicon particles 20 deposited thereon is placed in a rotary kiln, and a second mixed gas of acetylene and nitrogen is introduced thereinto. A second chemical vapor deposition is performed at a temperature of 550° C. for 4 hours to form a carbon coating layer 30 .

[0191] In the negative electrode active particles 100 prepared in this embodiment, the mass fraction of the porous carbon skeleton is 38%, the mass fraction of the silicon particles 20 is 48%, and the mass fraction of the carbon coating layer 30 is 14%.

[0192] Comparative Example 1

[0193] The negative electrode active particles 100 of this comparative example were prepared by the following steps:

[0194] 1) carbonizing a phenolic resin-based carbon source in an inert atmosphere at 650° C. for 4 hours to obtain a first intermediate carbon matrix;

[0195] 2) placing the first intermediate carbon matrix in a sodium hydroxide aqueous solution having a molar concentration of 6 mol / L at a temperature of 100° C. for etching for 2 hours to obtain a second intermediate carbon matrix, wherein the mass ratio of the sodium hydroxide in the sodium hydroxide aqueous solution to the mass ratio of the first intermediate carbon matrix is ​​25%;

[0196] 3) The second intermediate substrate was placed in a tube furnace and calcined at 500° C. under a nitrogen atmosphere to obtain a porous carbon substrate 10. The obtained porous carbon substrate 10 had a particle size of 7.5 μm. The pore volume, specific surface area, and pore 11 distribution of the porous carbon substrate 10 of this comparative example are shown in Table 1 below.

[0197] 4) placing the porous carbon substrate 10 in a rotary kiln and performing a first chemical vapor deposition at 400° C. for 2 h using a first mixed gas of monosilane and nitrogen to deposit silicon particles 20 in the plurality of pores 11 of the porous carbon substrate 10, wherein the volume fraction of nitrogen in the first mixed gas is in the range of 20%, and the particle size of the silicon particles 20 in the porous carbon substrate 10 is 7 nm;

[0198] 5) The porous carbon substrate 10 with the silicon particles 20 deposited thereon is placed in a rotary kiln, and a second mixed gas of acetylene and nitrogen is introduced thereinto. A second chemical vapor deposition is performed at a temperature of 550° C. for 2.5 hours to form a carbon coating layer 30 .

[0199] In the negative electrode active particles 100 prepared in this comparative example, the mass fraction of the porous carbon skeleton is 45%, the mass fraction of the silicon particles 20 is 48%, and the mass fraction of the carbon coating layer 30 is 7%.

[0200] Comparative Example 2

[0201] The negative electrode active particles 100 of this comparative example were prepared by the following steps:

[0202] 1) carbonizing a phenolic resin-based carbon source in an inert atmosphere at 650° C. for 4 hours to obtain a first intermediate carbon matrix;

[0203] 2) placing the first intermediate carbon matrix in a sodium hydroxide aqueous solution having a molar concentration of 6 mol / L at a temperature of 100° C. for etching for 2 hours to obtain a second intermediate carbon matrix, wherein the mass ratio of the sodium hydroxide in the sodium hydroxide aqueous solution to the mass ratio of the first intermediate carbon matrix is ​​20%;

[0204] 3) The second intermediate substrate was placed in a tube furnace and calcined at 500° C. under a nitrogen atmosphere to obtain a porous carbon substrate 10. The obtained porous carbon substrate 10 had a particle size of 7.5 μm. The pore volume, specific surface area, and pore 11 distribution of the porous carbon substrate 10 of this comparative example are shown in Table 1 below.

[0205] 4) placing the porous carbon substrate 10 in a rotary kiln and performing a first chemical vapor deposition at 400° C. for 2 h using a first mixed gas of monosilane and nitrogen to deposit silicon particles 20 in the plurality of pores 11 of the porous carbon substrate 10, wherein the volume fraction of nitrogen in the first mixed gas is in the range of 20%, and the particle size of the silicon particles 20 in the porous carbon substrate 10 is 7 nm;

[0206] 5) The porous carbon substrate 10 with the silicon particles 20 deposited thereon is placed in a rotary kiln, and a second mixed gas of acetylene and nitrogen is introduced thereinto. A second chemical vapor deposition is performed at a temperature of 550° C. for 2 hours to form a carbon coating layer 30 .

[0207] In the negative electrode active particles 100 prepared in this comparative example, the mass fraction of the porous carbon skeleton is 47%, the mass fraction of the silicon particles 20 is 48%, and the mass fraction of the carbon coating layer 30 is 5%.

[0208] The negative electrode active particles 100 obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were tested:

[0209] 1) Pore 11 distribution and pore volume measurement method: A nitrogen adsorption instrument is used to measure the nitrogen adsorption and desorption performance of the negative electrode active particles 100 at a temperature of 77K to obtain pore volume and pore size data.

[0210] 2) Measurement of the size of the silicon particles 20: Using a laser particle size analyzer, the particle size of the silicon particles 20 is characterized based on the differences in the angles at which the silicon particles 20 of different particle sizes block the laser.

[0211] 3) Specific surface area measurement: A nitrogen adsorption instrument was used to measure the nitrogen adsorption and desorption properties of the negative electrode active particles 100 at a temperature of 77 K to obtain specific surface area data.

[0212] 4) Measurement of the expansion rate of the negative electrode active layer: The negative electrode active particles 100 were mixed with conductive carbon black, carbon nanotubes, and polyacrylic acid in a mass ratio of 82:8:2:8 to form a slurry. The slurry was coated on copper foil, vacuum dried, and roll-pressed to produce a negative electrode sheet. The thickness L1 of the negative electrode sheet was measured. The negative electrode sheet was then assembled into a button half-cell using a lithium sheet as a counter electrode. The button half-cell was discharged to 5 mV (i.e., fully charged), and the thickness L2 of the negative electrode sheet was measured. The expansion rate of the negative electrode active layer = (L2 - L1) / L1 × 100%.

[0213] 5) Battery Capacity Retention after 500 Cycles: 100% of the negative electrode active particles were mixed with graphite, PAA, and CNT in a mass ratio of 10:87:2.8:0.2 (i.e., a 500% gram capacity of the graphite and silicon mixture, i.e., a 1.5V capacity). The mixture was then applied to the negative electrode current collector, dried at 100°C, and roller-pressed with a pressure of 5t to produce the negative electrode sheet. The positive electrode active material, lithium cobalt oxide, was mixed with conductive carbon black (conductive agent) and PVDF as a binder in a mass ratio of 98:1:1 to form a slurry. The slurry was then applied to the positive electrode current collector, dried, and roller-pressed to produce the positive electrode sheet. The negative electrode sheet, the positive electrode sheet and the separator are made into a wound battery, and then aluminum-plastic film packaging, drying, liquid injection, formation, secondary packaging, capacity division and other processes are carried out to obtain the battery. After that, a 25°C cycle test is carried out. One cycle test includes: charging at a rate of 3.5C to 4.5V, charging at a constant voltage of 4.5V to 0.02C cutoff, and then discharging at a rate of 0.7C to 3.0V cutoff.

[0214] The cycle capacity retention rate and thickness expansion rate of the batteries formed by the negative electrode active particles 100 of the embodiments and comparative examples after 500 cycles are shown in Table 1 below.

[0215] The measurement results of each embodiment and comparative example are shown in Table 1 below.

[0216] Table 1 Measurement results of negative electrode active particles 100 of various embodiments and comparative examples

[0217] The test results of Examples 1 to 3 and Comparative Examples 1 to 2 show that the proportion of mesopores 112 in the pores 11 of the porous carbon matrix 10 of the negative electrode active particles 100 of Examples 1 to 3 is relatively high, while the proportion of micropores 111 is relatively low. As a result, the batteries using the negative electrode active particles 100 have a lower expansion rate. In addition, the batteries made using the negative electrode active particles 100 of the present application have a higher cycle capacity retention rate. In Comparative Examples 1 and 2, the proportion of mesopores 112 in the pores 11 of the porous carbon matrix 10 is relatively low, while the proportion of micropores 111 is relatively high. The batteries made using the negative electrode active particles 100 have a higher expansion rate. In addition, the batteries made using the negative electrode active particles 100 have a lower cycle capacity retention rate. This shows that the negative electrode active particles 100 of the embodiments of the present application can better buffer the expansion during lithium insertion overcharge and have a lower expansion rate, thereby enabling the batteries using the negative electrode active particles 100 of the present application to have a better cycle capacity retention rate and a longer service life.

[0218] It can also be seen from the test data in Table 1 that, compared with Comparative Examples 1 and 2, the ultimate compaction density of the negative electrode active particles 100 of Examples 1 to 3 is reduced, but still remains at a relatively high density.

[0219] Referring to Figures 7 to 9, an embodiment of the present application further provides a battery 400, which includes: an electrolyte, a positive electrode sheet 410, a separator 420 and a negative electrode sheet 430, wherein the positive electrode sheet 410 is at least partially immersed in the electrolyte; the separator 420 is located on one side of the positive electrode sheet 410 and is at least partially immersed in the electrolyte; the negative electrode sheet 430 is arranged on the side of the separator 420 away from the positive electrode sheet 410 and is at least partially immersed in the electrolyte, the negative electrode sheet 430 includes a negative electrode collector 431 and a negative electrode active layer 432 arranged on the surface of the negative electrode collector 431, and the negative electrode active layer 432 includes the negative electrode active particles 100 of the embodiment of the present application.

[0220] The battery 400 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, a sodium-ion battery, or a magnesium-ion battery.

[0221] It is understood that the positive electrode sheet 410, the separator 420, and the negative electrode sheet 430 are stacked in sequence. The positive electrode sheet 410, the separator 420, and the negative electrode sheet 430 are stacked in sequence to form an electrode assembly. The electrode assembly can be, but is not limited to, a wound structure, a laminated structure, etc., and this application does not specifically limit this.

[0222] It should be noted that the positive electrode sheet 410 and the negative electrode sheet 430 can be collectively referred to as electrode sheets. In other words, the electrode sheets include the positive electrode sheet 410 and the negative electrode sheet 430 .

[0223] Please also refer to FIG. 10 . Optionally, the positive electrode sheet 410 includes a positive electrode current collector 411 and a positive electrode active layer 412 covering the surface of the positive electrode current collector 411 .

[0224] The positive electrode current collector 411 may be, but is not limited to, an aluminum sheet.

[0225] Optionally, the electrolyte may include but is not limited to lithium hexafluorophosphate (LiPF6) and the like.

[0226] Optionally, the diaphragm 420 may be, but is not limited to, at least one of a polypropylene film (PP) and a polyethylene film (PE).

[0227] Optionally, the negative electrode current collector 431 may be, but is not limited to, a copper sheet.

[0228] Optionally, the negative electrode active layer 432 further includes a negative electrode conductive agent and a negative electrode binder. It can be understood that the negative electrode active particles 100, the negative electrode conductive agent and the binder are uniformly dispersed.

[0229] Optionally, the negative electrode conductive agent may be, but is not limited to, conductive carbon black (SP for short) or carbon nanotubes (CNT for short).

[0230] Optionally, the negative electrode binder may be, but is not limited to, polyacrylic acid (PAA for short).

[0231] Optionally, the negative electrode active layer 432 may be disposed on one surface or multiple surfaces of the negative electrode current collector 431 .

[0232] In some embodiments, the battery 400 further includes a housing 440 and an end cap assembly 450. The housing 440 and the end cap assembly 450 enclose a housing for accommodating the electrolyte, the positive electrode sheet 410, the separator 420, and the negative electrode sheet 430. The end cap assembly 450 includes a positive electrode post and a negative electrode post. The positive electrode post is electrically connected to the positive electrode sheet 410, and the negative electrode post is electrically connected to the negative electrode sheet 430. The positive electrode post and the negative electrode post are used to electrically connect the battery 400 to an electrical device or other battery 400.

[0233] It can be understood that the battery 400 described in this embodiment is merely one form of the battery 400 used by the negative electrode active particles 100, and should not be understood as a limitation on the battery 400 provided in this application, nor should it be understood as a limitation on the negative electrode active particles 100 provided in each embodiment of this application.

[0234] 11 and 12 , an embodiment of the present application further provides an electronic device 500 , which includes a device body 510 and the battery 400 described in the embodiment of the present application, wherein the battery 400 is used to power the device body 510 .

[0235] The electronic device 500 of the embodiment of the present application can be, but is not limited to, a portable electronic device 500 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.

[0236] For a detailed description of the battery 400 , please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0237] It can be understood that the electronic device 500 described in this embodiment is merely a form of electronic device 500 used by the battery 400, and should not be understood as a limitation on the electronic device 500 provided in this application, nor should it be understood as a limitation on the battery 400 provided in each embodiment of this application.

[0238] Optionally, the device body 510 of the embodiment of the present application further includes a display screen 511, a middle frame 513, and a housing 515. The housing 515 is disposed opposite the display screen 511, the middle frame 513 is located between the display screen 511 and the housing 515, and the sidewalls of the middle frame 513 are exposed to the display screen 511 and the housing 515. The middle frame 513 and the housing 515 enclose an accommodating space, which is used to accommodate the battery 400. The display screen 511 is electrically connected to the battery 400, and the battery 400 provides power for the display screen 511.

[0239] Optionally, the display screen 511 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.

[0240] Please also refer to Figure 13. Optionally, the device body 510 of the present application further includes a processor 517 and a memory 516. The processor 517 and the memory 516 are disposed in the accommodation space. The processor 517 is electrically connected to the battery 400, the display screen 511, and the memory 516, respectively. The processor 517 is used to control the display screen 511 to display, and the memory 516 is used to store program codes required for the operation of the processor 517, the program codes required to control the display screen 511, the display content of the display screen 511, etc.

[0241] Optionally, the processor 517 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 517 is used to execute various types of digital storage instructions, such as software or firmware programs stored in the memory 516, which enables the computing device to provide a wide variety of services.

[0242] Optionally, the memory 516 may include volatile memory, such as random access memory (RAM); the memory 516 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 516 may also include a combination of the aforementioned types of memory 516.

[0243] In some embodiments, the device body 510 of the present embodiment further includes a camera module 518, which is disposed in the accommodation space. The camera module 518 is electrically connected to the processor 517 and the battery 400, respectively, for taking pictures under the control of the processor 517. The battery 400 also provides power to the camera module 518.

[0244] Optionally, the housing 515 has a light-transmitting portion (not shown), and the camera module 518 can capture images through the light-transmitting portion on the housing 515. That is, the camera module 518 in this embodiment is a rear-facing camera module 518. It is understood that in other embodiments, the light-transmitting portion can be provided on the display screen 511, that is, the camera module 518 is a front-facing camera module 518. 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, glass, etc.

[0245] 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.

[0246] 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 negative electrode active particle, characterized in that: include: A porous carbon matrix having a plurality of pores, wherein the plurality of pores include micropores, mesopores, and macropores, wherein the micropores account for 5% to 35%, the mesopores account for 60% to 90%, and the macropores account for 4% to 6% of the plurality of pores; and Silicon particles are distributed in the plurality of pores.

2. The negative electrode active particle according to claim 1, characterized in that The pore volume of the porous carbon matrix is in the range of 1.0 cm 3 / g to 2.0cm 3 / g.

3. The negative electrode active particle according to claim 2, characterized in that: The pore volume of the porous carbon matrix is in the range of 1.0 cm 3 / g to 1.6m 3 / g.

4. The negative electrode active particle according to claim 1, characterized in that The specific surface area S of the porous carbon matrix is in the range of 500 m 2 / g≤S≤3000m 2 / g.

5. The negative electrode active particle according to claim 1, characterized in that The particle size d1 of the silicon particles is in the range of 6 nm ≤ d1 ≤ 10 nm.

6. The negative electrode active particle according to claim 1, characterized in that In the negative electrode active particles, the mass fraction of the silicon particles ranges from 45% to 50%.

7. The negative electrode active particle according to claim 1, characterized in that In the porous carbon matrix, the mass fraction of oxygen atoms is less than or equal to 2%; and the range of the median particle size DV50 of the porous carbon matrix is 7 μm≤DV50≤9 μm.

8. The negative electrode active particle according to any one of claims 1 to 7, characterized in that: The negative electrode active particles further include a carbon coating layer, which wraps the surface of the porous carbon matrix and closes multiple pores of the porous carbon matrix; in the negative electrode active particles, the mass fraction of the carbon coating layer ranges from 10% to 15%.

9. The negative electrode active particle according to claim 8, characterized in that: In the negative electrode active particles, the mass fraction of the carbon coating layer ranges from 10.5% to 14.5%.

10. A method for preparing negative electrode active particles, characterized in that: include: Prepare a porous carbon matrix, wherein the porous carbon matrix has a plurality of pores, wherein the plurality of pores include micropores, mesopores, and macropores, wherein the number of the micropores accounts for 5% to 35%, the number of the mesopores accounts for 60% to 90%, and the number of the macropores accounts for 4% to 6%; as well as A silicon source gas is introduced into the porous carbon matrix to deposit silicon particles in the pores of the porous carbon matrix.

11. The method for preparing negative electrode active particles according to claim 10, characterized in that: The preparation of the porous carbon matrix comprises: providing a carbon source and carbonizing the carbon source to obtain a first intermediate carbon matrix; activating the first intermediate carbon matrix in a strong alkaline solution to form pores to obtain a second intermediate carbon matrix, wherein the molar concentration M of the strong alkaline solution is in the range of 5 mol / L≤M≤10 mol / L, and the mass ratio of the strong alkaline solution to the first intermediate carbon matrix is in the range of 30% to 40%; and The second intermediate carbon matrix is calcined to obtain a porous carbon matrix.

12. The method for preparing negative electrode active particles according to claim 11, characterized in that: The providing a carbon source and carbonizing the carbon source to obtain a first intermediate carbon matrix comprises: A carbon source is provided, and the carbon source is carbonized in an inert atmosphere at a temperature of 600° C. to 800° C. for a carbonization time of 3 hours to 6 hours to obtain a first intermediate carbon matrix.

13. The method for preparing negative electrode active particles according to claim 11, wherein: The activating and forming pores in the first intermediate carbon matrix in a strong alkaline solution comprises: The first intermediate matrix is mixed with a pore-forming agent and placed in a constant temperature device at 90° C. to 110° C. for activation and pore formation.

14. The method for preparing negative electrode active particles according to claim 11, wherein: After the activation and pore formation and before the calcination of the second intermediate carbon matrix, the preparation method further comprises: The second intermediate carbon substrate is cleaned.

15. The method for preparing negative electrode active particles according to claim 10, characterized in that: The step of introducing a silicon source gas into the porous carbon matrix to deposit silicon particles in a plurality of pores of the porous carbon matrix comprises: A first mixed gas is introduced into the porous carbon matrix, and a first chemical vapor deposition is performed at a temperature of 380°C to 450°C to deposit silicon particles in multiple pores of the porous carbon matrix, wherein the first mixed gas includes a silicon source gas and a first protective gas, and the volume fraction of the first protective gas in the first mixed gas ranges from 10% to 30%, and the flow rate of the first mixed gas ranges from 0.1m / s to 0.5m / s.

16. The method for preparing negative electrode active particles according to claim 15, characterized in that: The step of introducing the first mixed gas into the porous carbon matrix and performing a first chemical vapor deposition at a temperature of 380° C. to 450° C. to deposit silicon particles in the pores of the porous carbon matrix comprises: The porous carbon matrix is placed in a rotary furnace / fluidized bed, and a first mixed gas formed by mixing a silicon source gas and a first protective gas is introduced. The first chemical vapor deposition is performed at a temperature of 380°C to 450°C. The time of the first chemical vapor deposition is 1h to 3h to deposit silicon particles in multiple pores of the porous carbon matrix.

17. The method for preparing negative electrode active particles according to claim 10, characterized in that: The preparation method further comprises: forming a carbon coating layer on the surface of the porous carbon matrix having the silicon particles to close the plurality of pores; The method of forming a carbon coating layer on the surface of the porous carbon matrix having the silicon particles to close the multiple pores includes: introducing a second mixed gas into the porous carbon matrix having silicon particles, and performing a second chemical vapor deposition at a temperature of 500°C to 700°C to form a carbon coating layer on the surface of the porous carbon matrix, wherein the second mixed gas includes an organic gas source and a second protective gas, and the flow rate of the second mixed gas ranges from 0.1m / s to 0.5m / s.

18. The method for preparing negative electrode active particles according to claim 17, wherein: The second mixed gas is introduced into the porous carbon matrix having silicon particles, and a second chemical vapor deposition is performed at a temperature of 500° C. to 700° C. to form a carbon coating layer on the surface of the porous carbon matrix, comprising: The porous carbon matrix with silicon particles is placed in a rotary furnace / fluidized bed, and a second mixed gas consisting of an organic gas source and a second protective gas is introduced. The porous carbon matrix with silicon particles is soft-carbon coated at a temperature of 500°C to 700°C. The time of the second chemical vapor deposition is 1h to 4h.

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 A negative electrode sheet, wherein the negative electrode sheet is arranged on the side of the separator away from the positive electrode sheet and is at least partially immersed in the electrolyte, the negative electrode sheet includes a negative electrode collector and a negative electrode active layer arranged on the surface of the negative electrode collector, and the negative electrode active layer includes the negative electrode active particles according to any one of claims 1 to 9 or the negative electrode active particles prepared by the preparation method of the negative electrode active particles according to any one of claims 10 to 18.

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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