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

Abstract

The present application provides a negative electrode active particle, a preparation method therefor, a negative electrode sheet, a battery, and an electronic device. The negative electrode active particle of the present application comprises a matrix particle, and a plurality of carbon microspheres, wherein the plurality of carbon microspheres are distributed on the surface of the matrix particle, and the average particle size d1 of the carbon microspheres and the average particle size d2 of the matrix particle satisfy the following relational expression: 0.001≤d1 / d2≤0.5. The negative electrode active particle of the present application have good cycle performance.

Description

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

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

[0002] With the development of electronic devices, there is a growing demand for higher energy density in batteries, with the goal of longer battery life and thinner dimensions. However, existing materials with high theoretical specific capacities (such as silicon, which has a theoretical specific capacity of 4200 mAh / g) suffer from poor cycling performance. Summary of the Invention

[0003] In a first aspect, the present application provides a negative electrode active particle, wherein the negative electrode active particle comprises:

[0004] base particles; and

[0005] A plurality of carbon microspheres are distributed on the surface of the matrix particles, and an average particle size d1 of the carbon microspheres and an average particle size d2 of the matrix particles satisfy the relationship: 0.001≤d1 / d2≤0.5.

[0006] In a second aspect, the present application further provides a method for preparing negative electrode active particles, which comprises:

[0007] providing substrate particles; and

[0008] A plurality of carbon microspheres are formed on the surface of the base particles, wherein an average particle size d1 of the carbon microspheres and an average particle size d2 of the base particles satisfy the relationship: 0.001≤d1 / d2≤0.5.

[0009] In a third aspect, the present application further provides a negative electrode active particle, the negative electrode active particle comprising: a base particle, the base particle comprising:

[0010] A porous skeleton having a plurality of pores;

[0011] silicon particles, the silicon particles being located in the plurality of pores, with gaps between the silicon particles and inner walls of the pores; and

[0012] A carbon coating layer, wherein the carbon coating layer is wrapped around the periphery of the porous skeleton to seal the gaps and form closed pores in the gaps;

[0013] Among them, the average sphericity of the base particles is greater than or equal to 0.8, the average mass fraction of the silicon particles in the negative electrode active material composed of multiple negative electrode active particles is A, greater than or equal to 80%, and the mass fraction of the silicon particles in the negative electrode active particles ranges from A-10wt% to A+10wt%.

[0014] In a fourth aspect, the present application further provides a method for preparing negative electrode active particles, wherein the negative electrode active particles include matrix particles, and the preparation method comprises:

[0015] Providing a porous skeleton, wherein the porous skeleton has a plurality of pores, and the average sphericity of the porous skeleton is greater than or equal to 0.8;

[0016] introducing a silicon source gas into the porous skeleton to deposit silicon particles in the plurality of pores; and

[0017] A carbon coating layer is formed on the surface of the porous skeleton having the silicon particles to obtain base particles; wherein the base particles include a porous skeleton, silicon particles and a carbon coating layer; the silicon particles are located in the multiple pores, and there is a gap between the silicon particles and the inner wall of the pore; the carbon coating layer is wrapped around the periphery of the porous skeleton to seal the gap and form the gap into a closed hole; the average sphericity of the base particles is greater than or equal to 0.8, the average mass fraction of the silicon particles in the negative electrode active material composed of the multiple negative electrode active particles is A, which is greater than or equal to 80%, and the mass fraction of the silicon particles in the negative electrode active particles ranges from A-10wt% to A+10wt%.

[0018] In a fifth aspect, the present application further provides a negative electrode sheet, comprising:

[0019] a negative electrode current collector; and

[0020] A negative electrode active layer is provided on the surface of the negative electrode current collector, and the negative electrode active layer comprises the negative electrode active particles described in the embodiment of the present application or the negative electrode active particles prepared by the preparation method of the negative electrode active particles described in the embodiment of the present application.

[0021] In a sixth aspect, the present application further provides a battery comprising:

[0022] electrolyte;

[0023] a positive electrode sheet, wherein the positive electrode sheet is at least partially immersed in the electrolyte;

[0024] a diaphragm, the diaphragm being located on one side of the positive electrode sheet and at least partially immersed in the electrolyte, and

[0025] The negative electrode plate described in the embodiment of the present application is arranged on the side of the separator away from the positive electrode plate and is at least partially immersed in the electrolyte.

[0026] In a seventh aspect, the present application further provides an electronic device, comprising:

[0027] the device itself; and

[0028] The battery described in the embodiment of the present application is used to power the device body. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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.

[0030] FIG1 is a schematic diagram of the structure of negative electrode active particles according to an embodiment of the present application.

[0031] FIG2 is a schematic structural diagram of negative electrode active particles according to another embodiment of the present application.

[0032] FIG3 is a schematic structural diagram of a base particle according to an embodiment of the present application.

[0033] FIG4 is a schematic structural diagram of negative electrode active particles according to another embodiment of the present application.

[0034] FIG5 is a schematic structural diagram of negative electrode active particles according to another embodiment of the present application.

[0035] FIG6 is a schematic flow chart of a method for preparing negative electrode active particles according to an embodiment of the present application.

[0036] FIG7 is a schematic flow chart of a method for preparing base particles according to an embodiment of the present application.

[0037] FIG8 is a schematic structural diagram of a negative electrode plate according to an embodiment of the present application.

[0038] FIG9 is a schematic structural diagram of a battery according to an embodiment of the present application.

[0039] FIG10 is a schematic cross-sectional view of a battery according to an embodiment of the present application along the AA direction in FIG9 .

[0040] FIG11 is a schematic structural diagram of a positive electrode plate according to an embodiment of the present application.

[0041] FIG12 is a scanning electron microscope image of the base particles of Example 1 of the present application.

[0042] FIG13 is a color spectrometer image of the base particles of Example 1 of the present application.

[0043] FIG14 is a grayscale spectrometer diagram of the matrix particles of Example 1 of the present application.

[0044] FIG15 is a scanning electron microscope image of the negative electrode active particles of Example 6 of the present application.

[0045] FIG16 is a schematic structural diagram of an electronic device according to an embodiment of the present application.

[0046] FIG17 is a schematic diagram of the exploded structure of an electronic device according to an embodiment of the present application.

[0047] FIG18 is a circuit block diagram of an electronic device according to an embodiment of the present application.

[0048] Explanation of the figure numbers: 100-negative electrode active particles, 10-base particles, 11-porous skeleton, 111-pores, 12-silicon particles, 13-carbon coating layer, 14-closed pores, 20-carbon microspheres, 30-wrapping layer, 400-negative electrode plate, 410-negative electrode current collector, 420-negative electrode active layer, 500-battery, 510-positive electrode plate, 511-positive electrode current collector, 513-positive electrode active layer, 530-diaphragm, 550-housing, 570-end cover assembly, 600-electronic device, 610-device body, 611-display, 613-middle frame, 615-housing, 616-memory, 617-processor, 618-camera module. DETAILED DESCRIPTION

[0049] 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.

[0050] 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.

[0051] The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

[0052] 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.

[0053] 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.

[0054] Silicon material has a high theoretical specific capacity (the theoretical specific capacity of silicon is 4200mAh / g) and is the most promising negative electrode material for the next generation of high-energy density batteries. However, silicon itself will undergo a huge expansion during the lithium insertion process, which can easily cause the silicon particles to break, causing the silicon particles to repeatedly generate a new solid electrolyte interface (Solid Electrolyte Interphase, referred to as SEI film) during the charge and discharge process, which will accelerate the consumption of the electrolyte and cause the battery's cycle capacity retention rate to drop too quickly. In addition, the silicon particles will undergo a huge volume expansion during the lithium insertion process. The expansion and contraction of the silicon particles will also cause them to separate from the surrounding binder and conductive agent, causing the silicon particles to lose their conductive network, further increasing the expansion of the negative electrode sheet and further deteriorating the cycle performance.

[0055] Please refer to Figure 1. An embodiment of the present application provides a negative electrode active particle 100, which includes a base particle 10 and a plurality of carbon microspheres 20. The plurality of carbon microspheres 20 are distributed on the surface of the base particle 10. The average particle size d1 of the carbon microspheres 20 and the average particle size d2 of the base particle 10 satisfy the relationship: 0.001≤d1 / d2≤0.5.

[0056] Optionally, the base particles 10 may be, but are not limited to, silicon-based particles.

[0057] The negative electrode active particles 100 of the present application can be used in batteries (e.g., lithium batteries). Specifically, the negative electrode active particles 100 can be used as the negative electrode active material of the negative electrode active layer of the negative electrode sheet of the battery. The negative electrode active layer includes the negative electrode active particles 100, a negative electrode binder, and a negative electrode conductive agent.

[0058] Optionally, the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the matrix particles 10 can be, but is not limited to, 0.001, 0.002, 0.004, 0.006, 0.008, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc. If the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the base particles 10 is too small, it means that the size of the carbon microspheres 20 is small, the concave-convex structure on the surface of the negative electrode active particles 100 is not obvious, and the surface is too smooth. When applied to the negative electrode plate, it is not easy to be tightly entangled and connected with the negative electrode binder and the negative electrode conductive agent. In the process of lithium insertion and delithiation of the negative electrode active particles 100, the negative electrode active particles 100 are easily separated from the negative electrode binder and the negative electrode conductive agent, so that the negative electrode active layer of the negative electrode plate is easily pulverized, which reduces the cycle performance of the battery; if the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the base particles 10 is too large, the compaction density of the negative electrode active particles 100 will be reduced, the gram capacity of the negative electrode active particles 100 will be reduced, and the energy density of the battery using the negative electrode active particles 100 will be reduced. When the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the base particles 10 is between 0.001 and 0.5, a more suitable concave-convex structure can be formed on the surface of the negative electrode active particles 100. When applied to the negative electrode active layer of the negative electrode plate, the negative electrode active particles 100 can be entangled and connected with the binder and negative electrode conductive agent in the negative electrode active layer, thereby reducing the separation of the negative electrode binder and negative electrode conductive agent from the negative electrode active particles 100, which helps to maintain better cycle performance. In addition, the carbon microspheres 20 themselves have good electrical conductivity. The raised areas of the carbon microspheres 20 can also enable the negative electrode active particles 100 to maintain electrical contact with surrounding graphite particles or other negative electrode active particles 100, reducing the polarization phenomenon of the negative electrode plate and facilitating the improvement of the kinetic performance of the negative electrode active particles 100.

[0059] Furthermore, the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the matrix particles 10 is in the range of 0.005≤d1 / d2≤0.4. This allows a more suitable concave-convex structure to be formed on the surface of the negative electrode active particles 100. When applied to the negative electrode active layer of the negative electrode pole piece, it can be entangled and connected with the binder and negative electrode conductive agent in the negative electrode active layer, thereby reducing the situation where the negative electrode binder and negative electrode conductive agent are separated from the negative electrode active particles 100, which helps to maintain better cycle performance. In addition, the carbon microspheres 20 themselves have good conductivity. The raised positions of the carbon microspheres 20 can also enable the negative electrode active particles 100 to maintain electrical contact with the surrounding graphite particles or other negative electrode active particles 100, reduce the polarization phenomenon of the negative electrode pole piece, and help to improve the kinetic performance of the negative electrode active particles 100.

[0060] Furthermore, the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the matrix particles 10 is in the range of 0.01≤d1 / d2≤0.35. This allows the surface of the negative electrode active particles 100 to form a more suitable concave-convex structure. When applied to the negative electrode active layer of the negative electrode pole piece, it can be entangled and connected with the binder and negative electrode conductive agent in the negative electrode active layer, thereby reducing the situation where the negative electrode binder and negative electrode conductive agent are separated from the negative electrode active particles 100, which helps to maintain better cycle performance. In addition, the carbon microspheres 20 themselves have good conductivity. The raised positions of the carbon microspheres 20 can also enable the negative electrode active particles 100 to maintain electrical contact with the surrounding graphite particles or other negative electrode active particles 100, reduce the polarization phenomenon of the negative electrode pole piece, and help improve the kinetic performance of the negative electrode active particles 100.

[0061] Optionally, the plurality of carbon microspheres 20 may be closely arranged on the surface of the base particle 10 , or may be spaced apart on the surface of the base particle 10 .

[0062] The negative electrode active particles 100 of the embodiment of the present application include a base particle 10 and a plurality of carbon microspheres 20, the plurality of carbon microspheres 20 being distributed on the surface of the base particle 10, and the average particle size d1 of the carbon microspheres 20 and the average particle size d2 of the base particle 10 satisfy the relationship: 0.001≤d1 / d2≤0.5. This allows a relatively suitable concave-convex structure to be formed on the surface of the negative electrode active particles 100. When applied to the negative electrode active layer of the negative electrode plate, the negative electrode active particles 100 can be entangled and connected with the binder and negative electrode conductive agent in the negative electrode active layer, thereby reducing the negative electrode binder and negative electrode conductive agent from being separated from the negative electrode active particles 100 and losing the conductive network, thereby helping to maintain better cycle performance. In addition, the carbon microspheres 20 themselves have good conductivity. The raised positions of the carbon microspheres 20 can also enable the negative electrode active particles 100 to maintain electrical contact with the surrounding graphite particles or other negative electrode active particles 100, reducing the polarization phenomenon of the negative electrode plate, and helping to improve the kinetic performance of the negative electrode active particles 100.

[0063] In some embodiments, the average particle size d1 of the carbon microspheres 20 is in the range of 50 nm ≤ d1 ≤ 2000 nm (i.e., 2 μm). Specifically, the average particle size d1 of the carbon microspheres 20 can be, but is not limited to, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm, 2000 nm, etc. If the average particle size of the carbon microspheres 20 is too small, the negative electrode active particles 100 cannot play a network connection role when applied to the negative electrode plate of the battery, so that the negative electrode active particles 100 are easily separated from the negative electrode binder and the negative electrode conductive agent during the process of lithium insertion and delithiation, thereby making the negative electrode active layer of the negative electrode plate easily pulverized, reducing the cycle performance of the battery; if the average particle size d1 of the carbon microspheres 20 is too large, the compaction density of the negative electrode active particles 100 will be reduced, the gram capacity of the negative electrode active particles 100 will be reduced, and the energy density of the battery using the negative electrode active particles 100 will be reduced. When the average particle size of the carbon microspheres 20 is 50nm to 2000nm, the negative electrode active particles 100 can be used in the negative electrode plate of the battery to have a better network connection with the binder and the negative electrode conductive agent, thereby reducing the negative electrode active particles 100 from being easily separated from the negative electrode binder and the negative electrode conductive agent during the process of lithium insertion and delithiation, thereby improving the cycle performance of the battery; in addition, the negative electrode plate can have a more suitable compaction density, thereby increasing the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0064] Furthermore, the average particle size d1 of the carbon microspheres 20 is in the range of 80nm≤d1≤1500nm. This allows the negative electrode active particles 100 to form a better network connection with the binder and negative electrode conductive agent when used in the negative electrode plate of the battery, reducing the negative electrode active particles 100 from being easily separated from the negative electrode binder and negative electrode conductive agent during lithium insertion and removal, thereby improving the battery's cycle performance. In addition, the negative electrode plate can have a more appropriate compaction density, thereby increasing the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0065] Furthermore, the average particle size d1 of the carbon microspheres 20 is in the range of 100 nm ≤ d1 ≤ 1000 nm. This allows the negative electrode active particles 100 to form a better network connection with the binder and negative electrode conductive agent when used in the negative electrode plate of the battery, reducing the negative electrode active particles 100 from being easily separated from the negative electrode binder and negative electrode conductive agent during lithium insertion and removal, thereby improving the battery's cycle performance. In addition, the negative electrode plate can have a more appropriate compaction density, thereby increasing the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0066] Furthermore, the average particle size d1 of the carbon microspheres 20 is in the range of 100nm≤d1≤800nm. This allows the negative electrode active particles 100 to form a better network connection with the binder and negative electrode conductive agent when used in the negative electrode plate of the battery, reducing the negative electrode active particles 100 from being easily separated from the negative electrode binder and negative electrode conductive agent during lithium insertion and removal, thereby improving the battery's cycle performance. In addition, the negative electrode plate can have a more appropriate compaction density, thereby increasing the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0067] In some embodiments, the mass fraction of the plurality of carbon microspheres 20 in the negative electrode active particles 100 ranges from 0.05 wt % to 5 wt %. Specifically, the mass fraction of the plurality of carbon microspheres 20 in the negative electrode active particles 100 may be, but is not limited to, 0.05 wt %, 0.08 wt %, 0.1 wt %, 0.2 wt %, 0.4 wt %, 0.6 wt %, 0.8 wt %, 1 wt %, 1.5 wt %, 2 wt %, 2.5 wt %, 3 wt %, 3.5 wt %, 4 wt %, 4.5 wt %, 5 wt %, etc. In the negative electrode active particles 100, if the mass fraction of the multiple carbon microspheres 20 is too low, the number of carbon microspheres 20 is too small or the particle size of the carbon microspheres 20 is too small, which makes it impossible for the negative electrode active particles 100 to play a network connection role when applied to the negative electrode plate of the battery. The negative electrode active particles 100 are easily separated from the negative electrode binder and the negative electrode conductive agent during the process of lithium insertion and delithiation, thereby making the negative electrode active layer of the negative electrode plate easily pulverized, reducing the cycle performance of the battery; if the mass fraction of the carbon microspheres 20 is too large, it means that the particle size of the carbon microspheres 20 is too large, which will reduce the compaction density of the negative electrode active particles 100 and the gram capacity of the negative electrode active particles 100, thereby reducing the energy density of the battery using the negative electrode active particles 100. When the mass fraction of the plurality of carbon microspheres 20 in the negative electrode active particles 100 is in the range of 0.05wt% to 5wt%, the negative electrode active particles 100 can be used in the negative electrode plate of the battery to have a better network connection with the binder and the negative electrode conductive agent, thereby reducing the negative electrode active particles 100 from being easily separated from the negative electrode binder and the negative electrode conductive agent during the process of lithium insertion and delithiation, thereby improving the cycle performance of the battery; in addition, the negative electrode plate can have a more suitable compaction density, thereby improving the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0068] Furthermore, in the negative electrode active particles 100, the mass fraction of the plurality of carbon microspheres 20 ranges from 0.1 wt% to 4.5 wt%. This allows the negative electrode active particles 100 to form a better network connection with the binder and negative electrode conductive agent when used in the negative electrode sheet of the battery, reducing the likelihood of the negative electrode active particles 100 being easily separated from the negative electrode binder and negative electrode conductive agent during lithium insertion and removal, thereby improving the battery's cycle performance. Furthermore, the negative electrode sheet can have a more appropriate compaction density, thereby increasing the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0069] Furthermore, in the negative electrode active particles 100, the mass fraction of the plurality of carbon microspheres 20 ranges from 0.5 wt% to 4 wt%. This allows the negative electrode active particles 100 to form a better network connection with the binder and negative electrode conductive agent when used in the negative electrode sheet of the battery, reducing the likelihood of the negative electrode active particles 100 being easily separated from the negative electrode binder and negative electrode conductive agent during lithium insertion and removal, thereby improving the battery's cycle performance. Furthermore, the negative electrode sheet can have a more appropriate compaction density, thereby increasing the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0070] In some embodiments, the carbon microspheres 20 include carbon and a first doping element. Doping the carbon microspheres 20 with the first doping element can improve the first efficiency or kinetic performance of the negative electrode active particles 100.

[0071] Optionally, the mass fraction of the carbon element in the carbon microspheres 20 ranges from 50wt% to 100wt%; the first doping element includes at least one of nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; the mass fraction of the first doping element in the carbon microspheres 20 ranges from 0 to 50%.

[0072] 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.

[0073] It should be noted that when the mass fraction of the carbon element in the carbon microspheres 20 is 100 wt % and the mass fraction of the first doping element is 0, the carbon microspheres 20 only include the carbon element and do not contain other elements.

[0074] Specifically, the mass fraction of the carbon element in the carbon microspheres 20 can be, but is not limited to, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, 100wt%, etc.

[0075] Specifically, the mass fraction of the first doping element in the carbon microspheres 20 can be, but is not limited to, 0wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, etc.

[0076] In this embodiment, the doping of oxygen elements can alleviate the expansion of the matrix particles 10 during the lithium insertion process of the negative electrode active particles 100, thereby reducing the expansion rate of the negative electrode active particles 100 and improving the cycle performance of the battery using the negative electrode active particles 100; sulfur, nitrogen, and phosphorus doping can improve the conductivity of the negative electrode active particles 100, thereby improving the kinetic performance of the battery using the negative electrode active particles 100; lithium doping has a lithium replenishing effect, which is beneficial to improving the initial efficiency of the battery using the negative electrode active particles 100; aluminum, magnesium, titanium, sodium, copper, and iron can improve the conductivity of the carbon microspheres 20, thereby improving the kinetic performance of the battery using the negative electrode active particles 100.

[0077] Optionally, the shape of the carbon microspheres 20 may be, but is not limited to, spherical, ellipsoidal or other irregular shapes.

[0078] Please refer to Figure 2. In some embodiments, the negative electrode active particles 100 further include a coating layer 30, which is disposed on the surface of the plurality of carbon microspheres 20. The coating layer 30 includes at least one of a conductive agent and a binder. The coating layer 30 having a conductive agent or a binder is formed on the surface of the carbon microspheres 20. The conductive agent can improve the electronic conductivity of the negative electrode active particles 100. When the negative electrode active particles 100 are made into negative electrode sheets, the electrical connection between the negative electrode active particles 100 and adjacent negative electrode active particles 100 can be increased, thereby improving the dynamic performance of the negative electrode sheet. When the negative electrode active particles 100 are made into negative electrode sheets, the binder can enhance the bonding between adjacent negative electrode active particles 100, reduce the expansion of the negative electrode sheet during the lithium insertion and delithiation process, and improve the cycle performance of the negative electrode sheet.

[0079] Optionally, the conductive agent may be, but is not limited to, at least one of carbon nanotubes, graphene, etc. These conductive agents have good electrical conductivity and can better improve the electrical conductivity of the negative electrode active particles 100, thereby improving the kinetic performance and cycle performance of the negative electrode active particles 100.

[0080] Optionally, the mass fraction of the conductive agent in the negative electrode active particles 100 ranges from 0.01 wt % to 5 wt %. Specifically, the mass fraction of the conductive agent in the negative electrode active particles 100 may be, but is not limited to, 0.01 wt %, 0.05 wt %, 0.1 wt %, 0.3 wt %, 0.5 wt %, 0.8 wt %, 1 wt %, 1.5 wt %, 2 wt %, 2.5 wt %, 3 wt %, 3.5 wt %, 4 wt %, 4.5 wt %, 5 wt %, etc. If the mass fraction of the conductive agent in the negative electrode active particles 100 is too small, the conductivity of the negative electrode active particles 100 will not be improved; if the mass fraction of the conductive agent in the negative electrode active particles 100 is too large, the gram capacity of the negative electrode active particles 100 will be reduced.

[0081] Optionally, the binder may include at least one of polyacrylic acid (PAA), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polyacrylamide (PAM), and polyvinyl alcohol (PVA). These binders can better wrap around the surface of the carbon microspheres 20, thereby increasing the bonding performance between adjacent negative electrode active particles 100. This can effectively reduce the expansion rate of the negative electrode sheet when the negative electrode active particles 100 are applied to the negative electrode sheet.

[0082] Optionally, the mass fraction of the binder in the negative electrode active particles 100 ranges from 0.01 wt % to 5 wt %. Specifically, the mass fraction of the binder in the negative electrode active particles 100 may be, but is not limited to, 0.01 wt %, 0.05 wt %, 0.1 wt %, 0.3 wt %, 0.5 wt %, 0.8 wt %, 1 wt %, 1.5 wt %, 2 wt %, 2.5 wt %, 3 wt %, 3.5 wt %, 4 wt %, 4.5 wt %, 5 wt %, etc. If the mass fraction of the binder in the negative electrode active particles 100 is too small, it will not increase the bonding between adjacent negative electrode active particles 100. If the mass fraction of the binder in the negative electrode active particles 100 is too large, the gram capacity of the negative electrode active particles 100 will be reduced.

[0083] Please refer to Figures 3 to 5. In some embodiments, the base particle 10 includes a porous skeleton 11, silicon particles 12 and a carbon coating layer 13; the porous skeleton 11 has a plurality of pores 111, and the average sphericity of the porous skeleton 11 is greater than or equal to 0.8; the silicon particles 12 are located in the plurality of pores 111, and there is a gap between the silicon particles 12 and the inner wall of the pore 111; the carbon coating layer 13 is wrapped around the outer periphery of the porous skeleton 11 to close the gap and form the gap into a closed hole 14.

[0084] It can be understood that the carbon coating layer 13 is used to seal the pores 111 of the porous skeleton 11 to prevent the silicon particles 12 from being exposed on the surface of the negative electrode active particles 100. The porous skeleton 11 and the silicon particles 12 are all wrapped in the carbon coating layer 13, and the gaps between the silicon particles 12 and the porous inner wall form closed pores 14. When the silicon particles 12 are exposed on the surface of the negative electrode active particles 100, the silicon particles 12 are in direct contact with the electrolyte, and side reactions will occur, consuming active silicon and electrolyte, reducing the specific capacity of the silicon particles 12, and causing 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 carbon coating layer 13 can prevent the silicon particles 12 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.

[0085] It should be noted that there are a plurality of closed pores 14 , and the plurality of closed pores 14 are dispersed in the negative electrode active particles 100 .

[0086] Specifically, the average sphericity of the porous skeleton 11 can be, but not limited to, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1.0, etc. If the sphericity of the porous skeleton 11 is too low, the uniformity of the distribution of the silicon particles 12 and the uniformity of the size of the silicon particles 12 during silicon deposition in the porous skeleton 11 are reduced, thereby making the anisotropy of the porous skeleton 11 more obvious. In the process of lithium insertion of the negative electrode particles, the isotropic expansion rates of the negative electrode active particles 100 vary greatly, thereby reducing the cycle capacity retention rate of the battery using the negative electrode active particles 100. The better the sphericity of the porous skeleton 11, the more conducive it is to improving the transmission of the silicon source gas in the porous skeleton 11 during silicon deposition, so that the silicon source gas More uniform deposition in the multiple pores 111 of the porous skeleton 11 allows the silicon particles 12 to be deposited more evenly, improving the uniformity of the distribution of the silicon particles 12 in the porous skeleton 11 and the uniformity of the size of the silicon particles 12, so that the expansion of the silicon particles 12 can be better dispersed when the negative electrode active particles 100 are embedded in lithium. Each silicon particle 12 in the porous skeleton 11 has more sufficient expansion space to buffer the expansion of the silicon particles 12, reducing the damage to the negative electrode active particles 100 during the lithium embedding process, and improving the cycle performance of the negative electrode active particles 100.

[0087] In this embodiment, the base particles 10 include a porous skeleton 11, silicon particles 12 and a carbon coating layer 13; the average sphericity of the porous skeleton 11 is greater than or equal to 0.8, which can improve the transmission of silicon source gas in the porous skeleton 11 during silicon deposition, so that the silicon source gas is more evenly deposited in the multiple pores 111 of the porous skeleton 11, so that the silicon particles 12 can be more evenly deposited, and the uniformity of the distribution of silicon particles 12 in the porous skeleton 11 and the uniformity of the size of silicon particles 12 are improved. In addition, the isotropy of the base particles 10 can also be improved, so that the expansion of the silicon particles 12 in the negative electrode active particles 100 can be better dispersed when lithium is inserted, and each silicon particle 12 in the porous skeleton 11 has more sufficient expansion space to buffer the expansion of the silicon particles 12, reduce the damage to the negative electrode active particles 100 during the lithium insertion process, and improve the cycle performance of the negative electrode active particles 100. There is a gap between the silicon particles 12 and the inner wall of the pore 111. The gap can better buffer the expansion of the silicon particles 12 when the negative electrode active particles 100 are embedded with lithium, thereby reducing the expansion rate of the negative electrode active particles 100; the carbon coating layer 13 can better confine the silicon particles 12 within the pore 111, thereby preventing the silicon particles 12 from overflowing during the lithium embedding process, reducing the side reactions of the silicon particles 12, and improving the cycle performance of the negative electrode active particles 100.

[0088] Optionally, the average sphericity of the base particles 10 is greater than or equal to 0.8. Specifically, the sphericity of the porous skeleton 11 can be, but is not limited to, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1.0, etc. If the sphericity of the base particles 10 is too small, the anisotropy of the base particles 10 increases, which increases the anisotropy of the expansion of the base particles 10 when the silicon particles 12 are embedded in lithium, and reduces the cycle performance of the negative electrode active particles 100; when the average sphericity of the base particles 10 is greater than or equal to 0.8, the isotropy of the base particles 10 can be improved, so that when the negative electrode active particles 100 are embedded in lithium, the expansion of the silicon particles 12 can be better dispersed, and each silicon particle 12 in the porous skeleton 11 has more sufficient expansion space to buffer the expansion of the silicon particles 12, reduce the expansion rate of the base particles 10, reduce the damage to the negative electrode active particles 100 during the lithium embedding process, and improve the cycle performance of the negative electrode active particles 100.

[0089] Optionally, the porous skeleton 11 may be a primary particle or a secondary particle. When the porous skeleton 11 is a primary particle, the porous skeleton 11 has better sphericity, so that the silicon particles 12 are deposited more uniformly on the porous skeleton 11.

[0090] In some embodiments, the porous skeleton 11 includes a carbon element and a second doping element, wherein the second doping element includes at least one of nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, silicon, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the porous skeleton 11, the mass fraction of the carbon element is greater than or equal to 80 wt%.

[0091] Optionally, in the porous skeleton 11 , the mass fraction of the carbon element ranges from 80 wt % to 100 wt %, and the mass fraction of the second doping element ranges from 0 to 20 wt %.

[0092] Specifically, in the porous skeleton 11, the mass fraction of the carbon element can be but is not limited to 80wt%, 82wt%, 84wt%, 86wt%, 88wt%, 90wt%, 92wt%, 94wt%, 86wt%, 98wt%, 100wt%, etc.

[0093] Specifically, in the porous skeleton 11, the mass fraction of the second doping element can be but is not limited to 0wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt%, 20wt%, etc.

[0094] In this embodiment, by doping the second doping element into the porous skeleton 11, the porous skeleton 11 can have higher strength, which can better prevent the negative electrode active particles 100 from breaking during the lithium insertion process, and improve the cycle capacity retention rate of the battery using the negative electrode active particles 100; in addition, the second doping element can improve the conductivity of the porous skeleton 11, and can improve the kinetic performance of the negative electrode active particles 100, thereby improving the kinetic performance of the battery using the negative electrode active particles 100.

[0095] In other embodiments, the porous skeleton 11 may be at least one of porous carbon, porous carbide (e.g., titanium carbide, TiC), porous nitride, porous metal organic compound, etc. Using these compounds as the porous skeleton 11 can better suppress the expansion of the silicon particles 12 during the lithium insertion process of the negative electrode active particles 100.

[0096] Optionally, the porous carbide may be, but is not limited to, at least one of VxC, TixC, SixC, WxC, TaxC, NbxC, ZrxC, BxC, MoxC, FexC, TixAlyC, TixSiyC, etc.

[0097] Optionally, the mass fraction of carbon element in the porous carbide ranges from 5% to 99%; specifically, the mass fraction of carbon element in the porous carbide can be but is not limited to 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%, etc.

[0098] Optionally, the porous nitride may be, but is not limited to, at least one of SixN, BxN, AlxN, TixN, GaxN, ZrxN, VxN, MoxN, WxN, etc.

[0099] Optionally, in the porous nitride, the mass fraction of nitrogen element ranges from 5% to 99%; specifically, in the porous nitride, the mass fraction of nitrogen element can be but is not limited to 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%, etc.

[0100] Optionally, the porous metal organic compound may be, but is not limited to, at least one of a Zn-based metal organic framework, a Ni-based metal organic framework, a Mn-based metal organic framework, a Cu-based metal organic framework, and the like.

[0101] Optionally, the average size of the pores 111 is less than or equal to 4 nm. Specifically, the average size of the pores 111 can be, but is not limited to, 4.0 nm, 3.8 nm, 3.6 nm, 3.4 nm, 3.0 nm, 3 nm, 2.8 nm, 2.6 nm, 2.4 nm, 2.2 nm, 2.0 nm, 1.8 nm, 1.6 nm, 1.4 nm, 1.2 nm, 1.0 nm, 0.8 nm, 0.6 nm, 0.5 nm, etc.

[0102] Furthermore, the average size of the pores 111 ranges from 0.8 nm to 4 nm.

[0103] Optionally, the pores 111 of the porous skeleton 11 may be tested by nitrogen adsorption-desorption method.

[0104] Optionally, the size of the closed pores 14 is less than or equal to 4 nm. Specifically, the size of the closed pores 14 may be, but is not limited to, less than or equal to 4.0 nm, less than or equal to 3.5 nm, less than or equal to 3 nm, less than or equal to 2.8 nm, less than or equal to 2.5 nm, less than or equal to 2.3 nm, less than or equal to 2 nm, less than or equal to 1.8 nm, less than or equal to 1.5 nm, less than or equal to 1.3 nm, less than or equal to 1 nm, less than or equal to 0.8 nm, less than or equal to 0.5 nm, etc.

[0105] Furthermore, the size of the closed pores 14 may be, but is not limited to, 0.4 nm to 4 nm. Furthermore, the size of the closed pores 14 may be, but is not limited to, 0.4 nm to 3 nm. Furthermore, the size of the closed pores 14 may be, but is not limited to, 0.4 nm to 2 nm.

[0106] In this embodiment, if the size of the closed pores 14 is too small, when the negative electrode active particles 100 are applied to the battery, during the charge and discharge process of the battery, the closed pores 14 are insufficient to buffer the expansion of the silicon particles 12 during the lithium insertion process, thereby increasing the expansion rate of the negative electrode active particles 100, increasing the rate of electrolyte consumption, and reducing the cycle capacity retention rate of the battery; if the size of the closed pores 14 is too large, the energy density of the negative electrode active particles 100 is reduced.

[0107] Optionally, the pore volume V of the porous skeleton 11 is greater than or equal to 0.3 cm 3 The “pore volume” in this application refers to the total volume of the pores 111 of the porous skeleton 11 per unit mass.

[0108] Optionally, the pore volume V of the porous skeleton 11 is in the range of 0.3 cm 3 / g to 1.5cm 3 Specifically, the pore volume V of the porous skeleton 11 may be, but is not limited to, 0.3 cm 3 / g, 0.4cm 3 / g, 0.5cm 3 / g, 0.6cm 3 / g, 0.7cm 3 / g, 0.8cm 3 / g, 0.9cm 3 / g, 1.0cm 3 / g, 1.1cm 3 / g, 1.2cm 3 / g, 1.3cm 3 / g, 1.4cm 3 / g, 1.5cm 3 / g, etc. If the pore volume of the porous skeleton 11 is too small, it is insufficient to deposit sufficient silicon particles 12, thereby reducing the gram capacity of the negative electrode active particles 100; if the pore volume of the porous skeleton 11 is too large, there are too many pores, which will also reduce the energy density of the negative electrode active particles 100. The porous skeleton 11 has a small proportion and is easily broken, thereby reducing the cycle performance of the negative electrode active particles 100.

[0109] In some embodiments, the average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is A, and the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from A-10wt% to A+10wt%.

[0110] Specifically, the average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is A, and the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from A-10wt% to A+10wt%, or A-8wt% to A+8wt%, or A-6wt% to A+6wt%, or A-4wt% to A+4wt%, or A-2wt% to A+2wt%.

[0111] Specifically, the mass fraction of the silicon particles 12 of the negative electrode active particles 100 may be greater than or equal to 80% and range from A-10wt% to A+10wt%; or, the mass fraction of the silicon particles 12 of the negative electrode active particles 100 may be greater than or equal to 85% and range from A-10wt% to A+10wt%; or, the mass fraction of the silicon particles 12 of the negative electrode active particles 100 may be greater than or equal to 90% and range from A-10wt% to A+10wt%; or, the mass fraction of the silicon particles 12 of the negative electrode active particles 100 may be greater than or equal to 95% and range from A-10wt% to A+10wt%; or, the mass fraction of the silicon particles 12 of the negative electrode active particles 100 may be greater than or equal to 98% and range from A-10wt% to A+10wt%.

[0112] In one specific embodiment, if the average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is 40 wt %, then the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from 30 wt % to 50 wt %. In another specific embodiment, if the average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is 50 wt %, then the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from 40 wt % to 60 wt %. In another specific embodiment, if the average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is 50 wt %, then the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from 45 wt % to 55 wt %. In another specific embodiment, if the average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is 50 wt %, then the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from 48 wt % to 52 wt %. In another specific embodiment, if the average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is 60 wt %, then the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from 50 wt % to 70 wt %.

[0113] In this embodiment, by ensuring that the mass fraction of the silicon particles 12 in more than 80% of the negative electrode active particles 100 is within the range of ±10wt%, the mass fraction of the silicon particles 12 in each negative electrode active particle 100 is more balanced, and the expansion rates of the negative electrode active particles 100 are closer when the negative electrode active particles 100 are embedded with lithium, thereby avoiding excessively high silicon particle 12 content and excessive expansion rate in some negative electrode active particles 100, thereby ensuring that the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0114] Optionally, in the negative electrode active particles 100, the mass fraction of the silicon particles 12 ranges from 20 wt% to 80 wt%. Specifically, in the negative electrode active particles 100, the mass fraction of the silicon particles 12 may be, but is not limited to, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, etc. In this embodiment, if the mass fraction of the silicon particles 12 is too low, the active material in the negative electrode active particles 100 is too little, thereby reducing the specific capacity of the negative electrode active particles 100; if the mass fraction of the silicon particles 12 is too high, the porous skeleton 11 is insufficient to support the expansion of the silicon particles 12 during the lithium insertion process of the negative electrode active particles 100, making the negative electrode active particles 100 easily ruptured, thereby affecting the cycle performance of the battery using the negative electrode active particles 100.

[0115] Optionally, greater than or equal to 90 wt % of the silicon particles 12 are distributed within the plurality of pores 111. It is understood that most of the silicon elements or silicon particles 12 in the negative electrode active particles 100 are distributed within the porous skeleton 11, and the content of silicon particles 12 outside the porous skeleton 11 is less than 10 wt %. Specifically, greater than or equal to 90 wt % of the silicon particles 12 can be distributed within the plurality of pores 111; or greater than or equal to 93 wt % of the silicon particles 12 can be distributed within the plurality of pores 111; or greater than or equal to 95 wt % of the silicon particles 12 can be distributed within the plurality of pores 111; or greater than or equal to 98 wt % of the silicon particles 12 can be distributed within the plurality of pores 111; or 100 wt % of the silicon particles 12 can be distributed within the plurality of pores 111, etc. The silicon particles 12 distributed outside the porous skeleton 11 are not constrained by the porous skeleton 11 when inserting lithium. Therefore, the more silicon particles 12 distributed outside the porous skeleton 11, the higher the expansion rate of the negative electrode active particles 100 when inserting lithium. When greater than or equal to 90wt% of the silicon particles 12 are distributed in the multiple pores 111, the expansion rate of the negative electrode active particles 100 when inserting lithium can be better reduced, thereby improving the cycle capacity retention rate of the negative electrode active particles 100.

[0116] In some embodiments, the silicon particles 12 meet at least one of the following conditions:

[0117] The silicon particles 12 include silicon element, and the mass fraction of the silicon element in the silicon particles 12 is greater than or equal to 50 wt %;

[0118] The silicon particles 12 also include a third doping element, which includes at least one of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the silicon particles 12, the mass fraction of the third doping element is less than or equal to 50 wt%.

[0119] It is understood that in some embodiments, the silicon particles 12 only include silicon. In other embodiments, the silicon particles 12 include silicon and a third doping element.

[0120] It can be understood that the mass fraction of the silicon element in the silicon particles 12 ranges from 50 wt % to 100 wt %; the mass fraction of the third doping element in the silicon particles 12 ranges from 0 to 50 wt %.

[0121] Specifically, in the silicon particles 12, the mass fraction of the silicon element can be but is not limited to 50wt%, 52wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, 100wt%, etc.

[0122] Specifically, in the silicon particles 12, the mass fraction of the third doping element can be but is not limited to 0, 1wt%, 3wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, etc.

[0123] In this embodiment, the doping of oxygen elements can alleviate the expansion of the matrix particles 10 during the lithium insertion process of the negative electrode active particles 100, thereby reducing the expansion rate of the negative electrode active particles 100 and improving the cycle performance of the battery using the negative electrode active particles 100; sulfur, nitrogen, and phosphorus doping can improve the conductivity of the negative electrode active particles 100, thereby improving the kinetic performance of the battery using the negative electrode active particles 100; lithium doping has a lithium replenishing effect, which is beneficial to improving the initial efficiency of the battery using the negative electrode active particles 100; aluminum, magnesium, titanium, sodium, copper, and iron can improve the conductivity of the silicon particles 12, thereby improving the kinetic performance of the battery using the negative electrode active particles 100.

[0124] Optionally, the range of the average particle size d3 of the silicon particles 12 is: 0.4nm≤d3≤4nm. Specifically, the average particle size d3 of the silicon particles 12 can be, but is not limited to, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1.0nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, 2.0nm, 2.3nm, 2.5nm, 2.8nm, 3.0nm, 3.3nm, 3.5nm, 3.8nm, 4.0nm, etc. If the average particle size of the silicon particles 12 is too small, silicon is in an atomic state and cannot form a silicon phase, which reduces the embedding of lithium ions and thereby reduces the specific capacity of the negative electrode active particles 100; if the average particle size of the silicon particles 12 is too large, it is easy to generate Li during the process of lithium embedding of the negative electrode active particles 100. 15 The Si4 crystal phase and phase transition cause higher internal stress and greater volume change in the negative electrode active particles 100, making the negative electrode active particles 100 more susceptible to breakage and reducing the cycle capacity retention rate of the negative electrode active particles 100. When the average particle size d3 of the silicon particles 12 is 0.4nm≤d3≤4nm, the silicon particles 12 are sufficiently small to minimize the pressure on the silicon particles 12 during lithium insertion and removal, thereby reducing the breakage of the negative electrode active particles 100 and ensuring the stability of the silicon structure, thereby further improving the cycle performance of the negative electrode active particles 100.

[0125] Furthermore, the average particle size d3 of the silicon particles 12 is in the range of 0.4 nm ≤ d3 ≤ 2 nm. When the average particle size of the silicon particles 12 is in this range, it is less likely to generate Li during the lithium insertion process of the negative electrode active particles 100. 15 The Si4 crystal phase can better improve the structural stability of the negative electrode active particles 100, so that the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0126] Furthermore, the average particle size d3 of the silicon particles 12 is in the range of 0.5 nm ≤ d3 ≤ 1.8 nm. When the average particle size of the silicon particles 12 is in this range, it is less likely to generate Li during the lithium insertion process of the negative electrode active particles 100. 15 The Si4 crystal phase can better improve the structural stability of the negative electrode active particles 100, so that the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0127] Furthermore, the average particle size d3 of the silicon particles 12 is in the range of 0.7 nm ≤ d3 ≤ 1.8 nm. When the average particle size of the silicon particles 12 is in this range, it is less likely to generate Li during the lithium insertion process of the negative electrode active particles 100.15 The Si4 crystal phase can better improve the structural stability of the negative electrode active particles 100, so that the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0128] Optionally, the average particle size of the silicon particles 12 can be measured in the following manner: the negative electrode active particles 100 are heated to 700°C in an inert atmosphere (such as nitrogen or argon) for 2 hours, and then cooled to room temperature, and an X-ray diffraction pattern of the heat-treated negative electrode active particles 100 is obtained. The half-width of the diffraction peak of Si (111) near the diffraction angle 2θ = 28.4° in the X-ray diffraction pattern of the heat-treated negative electrode active particles 100 is used to calculate the average particle size of the silicon particles 12 by the Scherrer method.

[0129] In some embodiments, the closed pores 14 and the silicon particles 12 satisfy the relationship 0.5≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° in the X-ray diffraction pattern of the negative electrode active particles 100, and 2θ is the intensity of the diffraction peak of Si(111) in the range of 2θ of 28.2° to 28.5° in the X-ray diffraction pattern of the negative electrode active particles 100; 2θ is the diffraction angle.

[0130] It should be noted that in the X-ray diffraction pattern of the negative electrode active particle 100, the diffraction intensity at a diffraction angle 2θ of 8.8° is the diffraction intensity of the closed pores 14 with a size of 0.4 nm in the negative electrode active particle 100. The diffraction intensity at a diffraction angle 2θ of 22° is the diffraction intensity of the closed pores 14 with a size of 1 nm in the negative electrode active particle 100. Ia is the minimum diffraction intensity of the closed pores 14 with a size of 0.4 nm to 1 nm in the X-ray diffraction pattern.

[0131] It should be noted that, during the actual test process, the diffraction angle of the diffraction peak of Si(111) may shift, but is basically within the range of 28.2° to 28.5°.

[0132] It should be noted that Ib is the intensity of the diffraction peak of Si(111) in the X-ray diffraction pattern.

[0133] It should be noted that in the X-ray diffraction pattern, the diffraction intensity at a diffraction angle 2θ of 8.8° is the diffraction intensity of closed pores 14 with a width of 0.4 nm in the X-ray diffraction pattern. The diffraction intensity at a diffraction angle 2θ of 22° is the diffraction intensity of closed pores 14 with a width of 1 nm in the X-ray diffraction pattern. Ia is the minimum diffraction intensity of closed pores 14 with a width ranging from 0.4 nm to 1 nm in the X-ray diffraction pattern.

[0134] Specifically, Ia / Ib can be, but is not limited to, 0.5, 0.52, 0.55, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.73, 0.75, 0.78, 0.8, 0.83, 0.85, 0.88, 0.9, 0.92, 0.95, etc. If Ia / Ib is too small, it means that the content of closed pores 14 is too low. When the negative electrode active particles 100 are used in a battery, during the charge and discharge process of the battery, the closed pores 14 are insufficient to buffer the expansion of the silicon particles 12 during lithium insertion, thereby increasing the expansion rate of the negative electrode active particles 100, making the negative electrode active particles 100 easily broken, and further, repeatedly forming a new SEI film on the surface of the negative electrode active particles 100, increasing the rate of electrolyte consumption and reducing the cycle capacity retention rate of the battery. If Ia / Ib is too large, it means that the content of closed pores 14 is too high, which reduces the energy density of the negative electrode active particles 100.

[0135] Furthermore, the closed pores 14 and the silicon particles 12 satisfy the relationship 0.6≤Ia / Ib≤0.95. This allows for better matching of the expansion of the closed pores 14 and the silicon particles 12 during lithium insertion in the negative electrode active particles 100, resulting in a lower expansion rate for the negative electrode active particles 100 during lithium insertion, making the negative electrode active particles 100 less susceptible to breakage during lithium insertion, thereby achieving a higher cycle capacity retention rate. Furthermore, the negative electrode active particles 100 also have a higher energy density.

[0136] Furthermore, the closed pores 14 and the silicon particles 12 satisfy the relationship 0.6≤Ia / Ib≤0.85. This allows for better matching of the expansion of the closed pores 14 and the silicon particles 12 during lithium insertion in the negative electrode active particles 100, resulting in a lower expansion rate for the negative electrode active particles 100 during lithium insertion, making the negative electrode active particles 100 less susceptible to breakage during lithium insertion, thereby achieving a higher cycle capacity retention rate. Furthermore, the negative electrode active particles 100 also have a higher energy density.

[0137] Optionally, the thickness of the carbon coating layer 13 ranges from 1 nm to 500 nm. Specifically, the thickness of the carbon coating layer 13 may be, but is not limited to, 1 nm, 3 nm, 5 nm, 8 nm, 10 nm, 15 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 150 nm, 200 nm, 300 nm, 400 nm, 500 nm, etc. In this embodiment, if the thickness of the carbon coating layer 13 is too thick, the carbon content in the negative electrode active particles 100 is too high, the proportion of silicon decreases, and thus the specific capacity of the negative electrode active particles 100 is reduced; if the thickness of the carbon coating layer 13 is too thin, the carbon coating layer 13 does not completely coat the porous skeleton 11, which easily leads to incomplete isolation of the silicon particles 12 from the electrolyte, increases side reactions, and reduces the cycle capacity retention rate of the negative electrode active particles 100.

[0138] Furthermore, the thickness of the carbon coating layer 13 is in the range of 2 nm to 400 nm, which can make the negative electrode active particles 100 have a higher specific capacity and a higher cycle capacity retention rate.

[0139] Furthermore, the thickness of the carbon coating layer 13 is in the range of 2 nm to 300 nm, which can make the negative electrode active particles 100 have a higher specific capacity and a higher cycle capacity retention rate.

[0140] Furthermore, the thickness of the carbon coating layer 13 is in the range of 5 nm to 100 nm, which can make the negative electrode active particles 100 have a higher specific capacity and a higher cycle capacity retention rate.

[0141] In some embodiments, the mass fraction of silicon in the negative electrode active particles 100 ranges from 5 wt % to 95 wt %. Furthermore, the mass fraction of silicon in the negative electrode active particles 100 ranges from 10 wt % to 85 wt %. Furthermore, the mass fraction of silicon in the negative electrode active particles 100 ranges from 15 wt % to 80 wt %. Furthermore, the mass fraction of silicon in the negative electrode active particles 100 ranges from 25 wt % to 70 wt %. Furthermore, the mass fraction of silicon in the negative electrode active particles 100 ranges from 30 wt % to 60 wt %. Specifically, in the negative electrode active particles 100, the mass fraction of the silicon element can be, but is not limited to, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, etc.

[0142] It can be understood that in the negative electrode active particles 100 , the mass fraction of elements other than silicon (ie, other elements) ranges from 5 wt % to 95 wt %.

[0143] It is understandable that, in some embodiments, not all of the silicon elements are present in the negative electrode active particles 100 in the form of silicon particles 12 , and not all of the silicon particles 12 used only include silicon elements.

[0144] Optionally, the negative electrode active particles 100 include silicon and other elements, and the other elements may be, but are not limited to, at least one of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, iron, etc.

[0145] In this embodiment, the mass fraction of silicon is too low, indicating that the mass fractions of other elements are too high, and the active material in the negative electrode active particles 100 is too little, thereby reducing the specific capacity of the negative electrode active particles 100; the mass fraction of silicon is too high, indicating that the mass fractions of other elements are too low, and during the lithium insertion process of the negative electrode active particles 100, the porous skeleton 11 is insufficient to support the expansion of the silicon particles 12, making the negative electrode active particles 100 easily ruptured, thereby affecting the cycle performance of the battery using the negative electrode active particles 100.

[0146] In some embodiments, the median particle size D50 of the negative electrode active particles 100 is in the range of 1 μm≤D50≤20 μm.

[0147] Specifically, the median particle size D50 of the negative electrode active particles 100 may be, but is not limited to, 1 μm, 3 μm, 5 μm, 7 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, etc.

[0148] In this embodiment, if the median particle size D50 of the negative electrode active particles 100 is too large, when the negative electrode active particles 100 are used in a lithium battery, the transmission path of lithium ions within the negative electrode active particles 100 increases, increasing the transmission impedance of lithium ions and leading to poor kinetics. If the median particle size D50 of the negative electrode active particles 100 is too small, the specific surface area of ​​the negative electrode active particles 100 increases, the contact area between the negative electrode active particles 100 and the electrolyte increases, and the SEI film increases. During the charge and discharge cycle of the battery, the repeated destruction and growth of the SEI film consumes more electrolyte, which easily reduces the cycle capacity retention rate of the battery. When the median particle size D50 of the negative electrode active particles 100 is within the range of 1μm≤D50≤20μm, the negative electrode active particles 100 can have good kinetic performance and a high cycle capacity retention rate.

[0149] Furthermore, the median particle size D50 of the negative electrode active particles 100 is in the range of 3 μm ≤ D50 ≤ 15 μm. When the median particle size of the negative electrode active particles 100 is within this range, the negative electrode active particles 100 can have good kinetic performance and high cycle capacity retention.

[0150] Furthermore, the median particle size D50 of the negative electrode active particles 100 is in the range of 5 μm ≤ D50 ≤ 12 μm. When the median particle size of the negative electrode active particles 100 is within this range, the negative electrode active particles 100 can have good kinetic performance and high cycle capacity retention.

[0151] Optionally, the specific surface area S of the negative electrode active particles 100 is in the range of 0.1 m 2 / g≤S≤30m 2 Specifically, the specific surface area S of the negative electrode active particles 100 may be, but is not limited to, 0.1 m 2 / g, 0.3m 2 / g, 0.5m 2 / g, 0.8m 2 / g、1m 2 / g、3m 2 / g、5m 2 / g、8m 2 / g、10m 2 / g、12m 2 / g、14m 2 / g、16m 2 / g、18m 2 / g, 20m 2 / g、22m 2 / g、24m 2 / g、26m 2 / g、28m 2 / g、30m 2 / g, etc. When the specific surface area of ​​the negative electrode active particles 100 is small, the contact area between the negative electrode active particles 100 and the electrolyte can be better reduced, thereby avoiding excessive consumption of electrolyte during the cycle and reducing the cycle capacity retention rate of the negative electrode particles; however, when the specific surface area of ​​the negative electrode active particles 100 is too small, the size of the negative electrode active particles 100 is large. The larger size increases the transmission path of lithium ions inside the negative electrode active particles 100, increases the impedance of lithium ion transmission, and deteriorates the kinetic performance of the negative electrode active particles 100; if the specific surface area of ​​the negative electrode active particles 100 is too large, when applied to a battery, the contact area between the negative electrode active particles 100 and the electrolyte increases, and the SEI film increases. During the charge and discharge cycle of the battery, the repeated destruction and growth of the SEI film consumes more electrolyte, which easily reduces the cycle capacity retention rate of the battery.

[0152] It should be noted that, unless otherwise specified, the "specific surface area" in this application refers to the BET specific surface area, which is the total surface area per unit mass of a material. "BET" is the initials of three scientists: Brunauer, Emmett, and Teller.

[0153] Furthermore, the specific surface area S of the negative electrode active particles 100 is in the range of: 1m 2 / g≤S≤20m 2 This can make the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0154] Furthermore, the specific surface area S of the negative electrode active particles 100 is in the range of: 1m 2 / g≤S≤10m 2 This can make the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0155] Optionally, the compaction density of the negative electrode active particles 100 under a pressure of 2 tons is in the range of 0.6 g / cm 3 to 1.3g / cm 3 Specifically, the compaction density of the negative electrode active particles 100 under a pressure of 2 tons may be, but is not limited to, 0.6 g / cm 3 , 0.7g / cm 3 , 0.8g / cm 3 , 0.9g / cm 3 , 1.0g / cm 3 , 1.1g / cm 3 , 1.2g / cm 3 , 1.3g / cm 3If the compaction density of the negative electrode active particles 100 under a pressure of 2 tons is too low, the energy density of the negative electrode sheet will be reduced when the negative electrode active particles 100 are made into the negative electrode sheet; if the compaction density of the negative electrode active particles 100 under a pressure of 2 tons is too high, the ion transmission rate in the negative electrode sheet will be reduced when the negative electrode active particles 100 are made into the negative electrode sheet, thereby reducing the dynamic performance of the negative electrode sheet; in addition, if the compaction density of the negative electrode active particles 100 under a pressure of 2 tons is too high, the voids in the negative electrode sheet will be too small, which will increase the expansion rate of the negative electrode sheet and reduce the cycle performance of the negative electrode sheet.

[0156] In some embodiments, the initial lithium insertion capacity of the negative electrode active particles 100 ranges from 1700 mAh / g to 2000 mAh / g. Specifically, the initial lithium insertion capacity of the negative electrode active particles 100 may be, but is not limited to, 1700 mAh / g, 1750 mAh / g, 1800 mAh / g, 1850 mAh / g, 1900 mAh / g, 1950 mAh / g, 2000 mAh / g, etc.

[0157] In some embodiments, the first delithiation specific capacity of the negative electrode active particles 100 ranges from 1600 mAh / g to 1900 mAh / g. Specifically, the first delithiation specific capacity of the negative electrode active particles 100 can be, but is not limited to, 1600 mAh / g, 1650 mAh / g, 1700 mAh / g, 1750 mAh / g, 1800 mAh / g, 1850 mAh / g, 1900 mAh / g, etc.

[0158] 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.

[0159] Referring to FIG. 6 , a method for preparing negative electrode active particles 100 according to an embodiment of the present application includes:

[0160] S201, providing base particles 10; and

[0161] For a detailed description of the base particles 10 , please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0162] S202 , forming a plurality of carbon microspheres 20 on the surface of the base particle 10 , wherein the average particle size d1 of the carbon microspheres 20 and the average particle size d2 of the base particle 10 satisfy the relationship: 0.001≤d1 / d2≤0.5.

[0163] For a detailed description of the carbon microspheres 20 , please refer to the corresponding description of the above embodiment, which will not be repeated here.

[0164] The negative electrode active particles 100 prepared by the method for preparing the negative electrode active particles 100 according to the embodiment of the present application include a base particle 10 and a plurality of carbon microspheres 20. The plurality of carbon microspheres 20 are distributed on the surface of the base particle 10. The average particle size d1 of the carbon microspheres 20 and the average particle size d2 of the base particle 10 satisfy the relationship: 0.001≤d1 / d2≤0.5. This allows for a relatively suitable concave-convex structure to be formed on the surface of the negative electrode active particle 100. When applied to the negative electrode active layer of a negative electrode sheet, the structure can be entangled and connected with the binder and negative electrode conductive agent within the negative electrode active layer, thereby reducing the possibility of the negative electrode binder and negative electrode conductive agent detaching from the negative electrode active particle 100 and losing the conductive network, thereby helping to maintain better cycle performance. In addition, the carbon microspheres 20 themselves have good conductivity. The raised positions of the carbon microspheres 20 can also enable the negative electrode active particles 100 to maintain electrical contact with the surrounding graphite particles or other negative electrode active particles 100, reducing the polarization phenomenon of the negative electrode plate, which is beneficial to improving the kinetic performance of the negative electrode active particles 100.

[0165] Referring to FIG. 7 , in some embodiments, in S201 , providing the base particles 10 includes:

[0166] S2011, providing a porous skeleton 11, wherein the porous skeleton 11 has a plurality of pores 111, and the average sphericity of the porous skeleton 11 is greater than or equal to 0.8;

[0167] For a detailed description of other features such as the porous skeleton 11 and the pores 111 , please refer to the description of the corresponding parts of the above embodiments, which will not be repeated here.

[0168] S2012, introducing a silicon source gas into the porous skeleton 11 to deposit silicon particles 12 in the plurality of pores 111; and

[0169] In some embodiments, the step of introducing a silicon source gas into the porous skeleton 11 to deposit silicon particles 12 in the plurality of pores 111 includes:

[0170] At a first temperature T1 of 400° C. ≤ T1 ≤ 700° C., a silicon source gas is introduced to deposit silicon particles 12 in the plurality of pores 111; wherein the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 111 of the porous skeleton 11 is in the range of 0.05 g / cm 3 ≤m / V'≤2.0g / cm 3 .

[0171] It should be noted that "the total volume V' of the plurality of pores 111 of the porous skeleton 11" refers to the sum of the volumes of all the pores 111 of the porous skeleton 11 in the reaction system. For example, the total volume V' of the plurality of pores 111 of the porous skeleton 11 = the weight m of the porous skeleton 11 involved in the reaction × the pore volume V of the porous skeleton 11. In other words, V' = mV.

[0172] Optionally, the silicon source gas may include but is not limited to at least one of monosilane, disilane, dichlorosilane, trichlorosilane, and the like.

[0173] Optionally, before the silicon source gas is introduced into the porous skeleton 11 , the silicon source gas may be mixed with the protective gas before being introduced, or the protective gas may be introduced at the same time as the silicon source gas is introduced.

[0174] Optionally, the protective gas may be, but is not limited to, at least one of argon, nitrogen, and the like.

[0175] Specifically, the first temperature T1 can be, but is not limited to, 400°C, 430°C, 450°C, 480°C, 500°C, 530°C, 550°C, 580°C, 600°C, 630°C, 650°C, 680°C, 700°C, etc. If the first temperature T1 is too high, the reaction speed of the silicon source gas will be too fast, and the silicon source gas will not have time to enter the pores 111 of the porous skeleton 11 before it begins to deposit. The deposition of silicon on the surface of the porous skeleton 11 will cause the negative electrode active particles 100 to embed lithium. When silicon expands, it is not restricted by the space of the porous skeleton 11, which increases the expansion rate of the entire negative electrode active particles 100, and the cycle performance of the battery using the negative electrode active particles 100 deteriorates. In addition, when silicon is deposited on the surface, the size of silicon will not be restricted by the size of the pores 111 in the porous skeleton 11, and will continue to grow. Excessive silicon size will result in the generation of Li when embedding lithium. 15 The Si4 phase further deteriorates the cycle performance of the battery using the negative electrode active particles 100 ; if the first temperature T1 is too low, the silicon source gas is difficult to decompose into silicon and deposit, and silicon particles 12 cannot be formed in the pores 111 of the porous skeleton 11 .

[0176] Specifically, the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 111 of the porous skeleton 11 may be, but is not limited to, 0.05 g / cm 3 , 0.08g / cm 3 , 0.1g / cm 3 , 0.15g / cm 3 , 0.2g / cm 3 , 0.25g / cm 3 , 0.3g / cm 3 , 0.4g / cm 3, 0.5g / cm 3 , 0.6g / cm 3 , 0.8g / cm 3 , 1.0g / cm 3 , 1.2g / cm 3 , 1.4 / cm 3 , 1.6g / cm 3 , 1.8g / cm 3 , 1.9g / cm 3 , 2.0g / cm 3 Etc. If the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 111 of the porous skeleton 11 is too small, the energy density of the negative electrode active particles 100 obtained will be too low; if the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 111 of the porous skeleton 11 is too large, the mass fraction of silicon in the negative electrode active particles 100 obtained will be too high, which will increase the expansion rate of the negative electrode active particles 100. During the lithium insertion process of the negative electrode active particles 100, the porous skeleton 11 is insufficient to support the expansion of the silicon particles 12, making the negative electrode active particles 100 easy to rupture, affecting the cycle performance of the battery using the negative electrode active particles 100. When the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 111 of the porous skeleton 11 is 0.05 g / cm 3 ≤m / V'≤2g / cm 3 When the negative electrode active particles 100 are added, the negative electrode active particles 100 can have a higher energy density and a lower expansion rate, so that the battery using the negative electrode active particles 100 has better cycle performance.

[0177] Furthermore, the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 111 of the porous skeleton 11 is in the range of 0.2 g / cm 3 ≤m / V'≤1.8g / cm 3 This allows the negative electrode active particles 100 to have a higher energy density and a lower expansion rate, thereby allowing the battery using the negative electrode active particles 100 to have better cycle performance.

[0178] Furthermore, the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 111 of the porous skeleton 11 is in the range of 0.5 g / cm 3 ≤m / V'≤1.8g / cm 3 This allows the negative electrode active particles 100 to have a higher energy density and a lower expansion rate, thereby allowing the battery using the negative electrode active particles 100 to have better cycle performance.

[0179] Optionally, the deposition time t of the silicon particles 12 is in the range of 3h≤t≤100h. Specifically, the deposition time t of the silicon particles 12 can be, but is not limited to, 3h, 5h, 8h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 50h, 60h, 70h, 80h, 90h, 100h, etc. If the deposition time t of the silicon particles 12 is too long, it is easy for the silicon particles 12 to grow too large, the formed silicon particles 12 are too large, and the size of the silicon phase in the negative electrode active particles 100 is too large, so that the negative electrode active particles 100 are more likely to generate Li when lithium is inserted. 15 Si4 crystal phase, during the formation of the crystal phase, the negative electrode active particles 100 will cause higher internal stress and produce greater volume changes, which will deteriorate the cycle performance of the negative electrode active particles 100; if the deposition time t of the silicon particles 12 is too short, the silicon content in the negative electrode active particles 100 will be reduced, thereby reducing the specific capacity of the negative electrode active particles 100.

[0180] S2013 , forming a carbon coating layer 13 on the surface of the porous skeleton 11 having the silicon particles 12 to obtain base particles 10 .

[0181] Among them, the base particles 10 include a porous skeleton 11, silicon particles 12 and a carbon coating layer 13; the silicon particles 12 are located in the multiple pores 111, and there is a gap between the silicon particles 12 and the inner wall of the pore 111; the carbon coating layer 13 is wrapped around the outer periphery of the porous skeleton 11 to close the gap and form the gap into a closed pore 14.

[0182] Optionally, forming a carbon coating layer 13 on the surface of the porous skeleton 11 having the silicon particles 12 includes: forming a carbon coating layer 13 on the surface of the porous skeleton 11 having the silicon particles 12 in a first organic carbon source at a second temperature T2 in the range of 500°C≤T2≤900°C.

[0183] Optionally, a first organic carbon source is added to the porous skeleton 11 having silicon particles 12 , and chemical vapor deposition (ie, carbon deposition) is performed at 500° C. to 900° C. to form a carbon coating layer 13 on the surface of the porous skeleton 11 having silicon particles 12 .

[0184] Optionally, the first organic carbon source includes a first organic gas and a first carrier gas; the first organic gas may be, but is not limited to, at least one of acetylene and methane, etc. The first carrier gas may be, but is not limited to, at least one of nitrogen and argon, etc.

[0185] Optionally, the volume concentration V1 of the first organic gas in the first organic carbon source ranges from 1% to 50%. Specifically, the volume concentration V1 of the first organic gas in the first organic carbon source can be, but is not limited to, 1%, 3%, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc. If the volume concentration V1 of the first organic gas in the first organic carbon source is too low, the rate of formation of the carbon coating layer 13 is reduced, thereby reducing production efficiency. If the volume concentration V1 of the first organic gas in the first organic carbon source is too high, the carbon deposition rate is too fast, resulting in uneven carbon deposition and failure to effectively enclose the silicon particles 12 in the pores 111 of the porous framework 11.

[0186] Optionally, the second temperature T2 may be, but is not limited to, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, etc. If the second temperature T2 is too low, the first organic carbon source is difficult to reduce; if the second temperature T2 is too high, carbon deposition is too rapid, which may result in uneven formation of the carbon coating layer 13 and difficulty in completely enclosing the silicon particles 12 within the pores 111 of the porous skeleton 11. This increases side reactions of the silicon particles 12 and reduces the cycle performance of the negative electrode active particles 100. Furthermore, if the second temperature T2 is too high, inert silicon carbide is easily generated, which reduces the energy density of the negative electrode active particles 100.

[0187] Optionally, the deposition time of the carbon coating layer 13 can be 1 minute to 3 hours, for example, 1 minute, 20 minutes, 30 minutes, 45 minutes, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc. If the deposition time of the carbon coating layer 13 is too short, the first organic carbon source is difficult to be reduced, and the carbon coating layer 13 is difficult to completely cover the porous skeleton 11, so that part of the silicon particles 12 is exposed, thereby increasing the side reaction between the negative electrode active particles 100 and the electrolyte; if the deposition time of the carbon coating layer 13 is too long, inert silicon carbide is easily generated, and the formed carbon coating layer 13 is too thick, which reduces the energy density of the negative electrode active particles 100.

[0188] Furthermore, the deposition time of the carbon coating layer 13 may be 1 hour to 3 hours, so that the formed carbon coating layer 13 can better seal the pores 111 or gaps and make the negative electrode active particles 100 have a higher energy density.

[0189] For detailed descriptions of the porous skeleton 11 , silicon particles 12 , carbon coating layer 13 , pores 111 , gaps, and closed pores 14 , please refer to the descriptions of the corresponding parts of the above embodiments, which will not be repeated here.

[0190] In some embodiments, in S202, forming a plurality of carbon microspheres 20 on the surface of the base particle 10 includes: placing the base particle 10 in a second organic carbon source at a third temperature T3 in the range of 300°C≤T3≤900°C to form a plurality of carbon microspheres 20 on the surface of the base particle 10.

[0191] In some embodiments, the second organic carbon source can be an organic carbon source solution, wherein the organic carbon source solution includes at least one of glucose solution, fructose solution, lactose solution, citric acid solution, sucrose solution, and the like.

[0192] In other embodiments, the second organic carbon source includes a second organic gas and a second carrier gas. Optionally, the second organic gas may be, but is not limited to, at least one of acetylene and methane. The second carrier gas may be, but is not limited to, at least one of nitrogen and argon.

[0193] Furthermore, when the second organic carbon source includes a second organic gas and a second carrier gas, the third temperature T3 at which the carbon microspheres 20 are deposited is in the range of 500° C. ≤ T3 ≤ 900° C. When the second organic carbon source includes an organic carbon source solution, the third temperature T3 at which the carbon microspheres 20 are formed is in the range of 300° C. ≤ T3 ≤ 900° C., i.e., the organic carbon source is carbonized at the third temperature to form the carbon microspheres 20.

[0194] Alternatively, the third temperature T3 may be, but is not limited to, 300° C., 350° C., 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700° C., 750° C., 800° C., 850° C., 900° C., etc. If the third temperature T3 is too low, the second organic carbon source may be difficult to reduce or carbonize to form the carbon microspheres 20. Furthermore, if the third temperature T3 is too low and the second organic carbon source includes a second organic gas, a coating layer may easily form after the second organic carbon source is deposited, making it difficult to form the carbon microspheres 20. If the third temperature T3 is too high, inert silicon carbide may be easily generated, thereby reducing the energy density of the negative electrode active particles 100.

[0195] Optionally, the volume concentration V2 of the second organic gas in the second organic carbon source ranges from 5% to 100%. Specifically, the volume concentration V2 of the second organic gas in the second organic carbon source can be, but is not limited to, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, 100%, etc. If the volume concentration V2 of the second organic gas in the second organic carbon source is too low, the carbon deposition rate is reduced, making it difficult to form unevenly deposited carbon microspheres 20 on the surface of the carbon coating layer 13.

[0196] Optionally, the deposition time of the carbon microspheres 20 can be 1 min to 3 h, for example, 1 min, 20 min, 30 min, 45 min, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc. If the deposition time of the carbon microspheres 20 is too short, the first organic carbon source is difficult to be reduced, and the carbon microspheres 20 are difficult to completely cover the porous skeleton 11, so that some silicon particles 12 are exposed, thereby increasing the side reaction between the negative electrode active particles 100 and the electrolyte; if the deposition time of the carbon microspheres 20 is too long, inert silicon carbide is easily generated, and the formed carbon microspheres 20 are too thick, which reduces the energy density of the negative electrode active particles 100.

[0197] Furthermore, the deposition time of the carbon microspheres 20 can be 1 hour to 3 hours, so that the formed carbon microspheres 20 can better close the pores 111 or gaps and make the negative electrode active particles 100 have a higher energy density.

[0198] In some embodiments, the first organic carbon source includes a first organic gas and a first carrier gas, the second organic carbon source includes a second organic gas and a second carrier gas, the second temperature T2 is lower than the third temperature T3, and the volume concentration of the first organic gas in the first organic carbon source is lower than the volume concentration of the second organic gas in the second organic carbon source.

[0199] In this embodiment, by making the second temperature T2 lower than the third temperature T3 and making the volume concentration of the first organic gas in the first organic carbon source lower than the volume concentration of the second organic gas in the second organic carbon source, the carbon deposition rate is slower when the first organic carbon source is used for chemical vapor deposition, so that the carbon deposition can be more uniform, and the pores 111 in the porous skeleton 11 can be better sealed, so that the carbon coating layer 13 can be better formed on the surface of the porous skeleton 11. When the second organic carbon source is used for chemical vapor deposition, the carbon deposition rate is faster, so that carbon microspheres 20 can be formed on the surface of the carbon coating layer 13, so that the surface of the negative active particles 100 forms a concave-convex structure. When applied to the negative active layer of the negative electrode sheet, it can be entangled and connected with the binder and negative conductive agent in the negative active layer, thereby reducing the situation where the negative binder and negative conductive agent are separated from the negative active particles 100 and lose the conductive network, which helps to maintain better cycle performance. In addition, the carbon microspheres 20 themselves have good conductivity. The raised positions of the carbon microspheres 20 can also enable the negative electrode active particles 100 to maintain electrical contact with the surrounding graphite particles or other negative electrode active particles 100, reducing the polarization phenomenon of the negative electrode plate, which is beneficial to improving the kinetic performance of the negative electrode active particles 100.

[0200] In some embodiments, the range of the difference T3-T2 between the third temperature T3 and the second temperature T2 is: 20° C. ≤ T3-T2 ≤ 250° C.;

[0201] Alternatively, a difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source is in the range of: 5%≤V2-V1≤99%;

[0202] Alternatively, the range of the difference T3-T2 between the third temperature T3 and the second temperature T2 is: 20°C ≤ T3-T2 ≤ 250°C, and the range of the difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source is: 5% ≤ V2-V1 ≤ 99%.

[0203] Specifically, the difference T3-T2 between the third temperature T3 and the second temperature T2 can be, but is not limited to, 20°C, 30°C, 50°C, 80°C, 100°C, 130°C, 150°C, 180°C, 200°C, 230°C, 250°C, etc. If the difference T3-T2 between the third temperature T3 and the second temperature T2 is too small, when both the third temperature T3 and the second temperature T2 are low, carbon microspheres 20 may not be formed during deposition. If both the third temperature T3 and the second temperature T2 are high, the carbon coating layer 13 may be deposited at a high carbon deposition rate, resulting in an uneven carbon coating layer 13 and difficulty in completely enclosing the silicon particles 12 within the pores 111 of the porous skeleton 11. This increases side reactions of the silicon particles 12 and reduces the cycle performance of the negative electrode active particles 100. Furthermore, when the second temperature T2 is too high, inert silicon carbide may be generated, reducing the energy density of the negative electrode active particles 100. When the difference T3-T2 between the third temperature T3 and the second temperature T2 is too large, inert silicon carbide is easily generated during the deposition of the silicon particles 12, which reduces the energy density of the negative electrode active particles 100.

[0204] Specifically, the difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source can be but is not limited to 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, 99%, etc. If the difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic carbon source is too small, it is possible that the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source are both high. When the carbon coating layer 13 is deposited, the deposition rate of the carbon coating layer 13 is too high, thereby reducing the uniformity of the deposition of the carbon coating layer 13 and reducing the cycle performance of the negative active particles 100. Or it is possible that the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic carbon source are both low, thereby reducing the production efficiency of the negative active particles 100; if the difference V2-V1 between the volume concentration V2 of the second organic carbon source and the volume concentration V1 of the first organic carbon source is too large, it is possible that the volume concentration V1 of the first organic gas in the first organic carbon source is too low, thereby reducing the production efficiency of the negative active particles 100.

[0205] Please refer to Figure 3 again. The embodiment of the present application also provides a negative electrode active particle 100, which includes a base particle 10, and the base particle 10 includes a porous skeleton 11, silicon particles 12 and a carbon coating layer 13; the porous skeleton 11 has a plurality of pores 111; the silicon particles 12 are located in the plurality of pores 111, and there is a gap between the silicon particles 12 and the inner wall of the pore 111; the carbon coating layer 13 is wrapped around the outer periphery of the porous skeleton 11 to seal the gap and form the gap into a closed hole 14.

[0206] The average sphericity of the base particles 10 is greater than or equal to 0.8. The average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is A, and the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from A-10 wt% to A+10 wt%.

[0207] For detailed descriptions of other aspects such as the negative electrode active particles 100, base particles 10, porous skeleton 11, silicon particles 12, carbon coating layer 13, pores 111, closed pores 14, etc., please refer to the description of the corresponding feature parts of the above embodiment, which will not be repeated here.

[0208] Optionally, the average sphericity of the base particles 10 is greater than or equal to 0.8. Specifically, the sphericity of the porous skeleton 11 can be, but is not limited to, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1.0, etc. If the sphericity of the base particles 10 is too small, the anisotropy of the base particles 10 increases, which increases the anisotropy of the expansion of the base particles 10 when the silicon particles 12 are embedded in lithium, and reduces the cycle performance of the negative electrode active particles 100; when the average sphericity of the base particles 10 is greater than or equal to 0.8, the isotropy of the base particles 10 can be improved, so that when the negative electrode active particles 100 are embedded in lithium, the expansion of the silicon particles 12 can be better dispersed, and each silicon particle 12 in the porous skeleton 11 has more sufficient expansion space to buffer the expansion of the silicon particles 12, reduce the expansion rate of the base particles 10, reduce the damage to the negative electrode active particles 100 during the lithium embedding process, and improve the cycle performance of the negative electrode active particles 100.

[0209] Optionally, the average sphericity of the porous skeleton 11 is greater than or equal to 0.8; specifically, the sphericity of the porous skeleton 11 can be, but is not limited to, 0.8, 0.82, 0.84, 0.86, 0.88, 0.9, 0.92, 0.94, 0.96, 0.98, 1.0, etc. If the sphericity of the porous skeleton 11 is too low, the uniformity of the distribution of the silicon particles 12 and the uniformity of the size of the silicon particles 12 during silicon deposition in the porous skeleton 11 are reduced, thereby making the anisotropy of the porous skeleton 11 more obvious. During the process of lithium insertion of the negative electrode particles, the isotropic expansion rates of the negative electrode active particles 100 vary greatly, thereby reducing the cycle capacity retention rate of the battery using the negative electrode active particles 100; the better the sphericity of the porous skeleton 11, the more conducive it is to improving the transmission of the silicon source gas in the porous skeleton 11 during silicon deposition, so that the silicon source gas More uniform deposition in the multiple pores 111 of the porous skeleton 11 allows the silicon particles 12 to be deposited more evenly, improving the uniformity of the distribution of the silicon particles 12 in the porous skeleton 11 and the uniformity of the size of the silicon particles 12, so that the expansion of the silicon particles 12 can be better dispersed when the negative electrode active particles 100 are embedded in lithium. Each silicon particle 12 in the porous skeleton 11 has more sufficient expansion space to buffer the expansion of the silicon particles 12, reducing the damage to the negative electrode active particles 100 during the lithium embedding process, and improving the cycle performance of the negative electrode active particles 100.

[0210] In addition, in this embodiment, by ensuring that the mass fraction of the silicon particles 12 in more than 80% of the negative electrode active particles 100 is within the range of ±10wt%, the mass fraction of the silicon particles 12 in each negative electrode active particle 100 is more balanced, and the expansion rates of the negative electrode active particles 100 are closer when the negative electrode active particles 100 are embedded with lithium, thereby avoiding excessively high silicon particle 12 content and excessive expansion rate in some negative electrode active particles 100, thereby ensuring that the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0211] In some embodiments, the closed pores 14 and the silicon particles 12 satisfy the relationship 0.5≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° in the X-ray diffraction pattern of the negative electrode active particles 100, and 2θ is the intensity of the diffraction peak of Si(111) in the range of 2θ of 28.2° to 28.5° in the X-ray diffraction pattern of the negative electrode active particles 100; 2θ is the diffraction angle.

[0212] Specifically, Ia / Ib can be, but is not limited to, 0.5, 0.52, 0.55, 0.58, 0.6, 0.62, 0.65, 0.68, 0.7, 0.73, 0.75, 0.78, 0.8, 0.83, 0.85, 0.88, 0.9, 0.92, 0.95, etc. If Ia / Ib is too small, it means that the content of closed pores 14 is too low. When the negative electrode active particles 100 are used in a battery, during the charge and discharge process of the battery, the closed pores 14 are insufficient to buffer the expansion of the silicon particles 12 during lithium insertion, thereby increasing the expansion rate of the negative electrode active particles 100, making the negative electrode active particles 100 easily broken, and further, repeatedly forming a new SEI film on the surface of the negative electrode active particles 100, increasing the rate of electrolyte consumption and reducing the cycle capacity retention rate of the battery. If Ia / Ib is too large, it means that the content of closed pores 14 is too high, which reduces the energy density of the negative electrode active particles 100.

[0213] For detailed descriptions of the closed pores 14, the silicon particles 12 and other aspects, please refer to the description of the corresponding feature parts of the above embodiment, which will not be repeated here.

[0214] In some embodiments, the mass fraction of the silicon particles 12 in the negative electrode active particles 100 ranges from 20 wt % to 80 wt %. Specifically, the mass fraction of the silicon particles 12 in the negative electrode active particles 100 may be, but is not limited to, 20 wt %, 25 wt %, 30 wt %, 35 wt %, 40 wt %, 50 wt %, 60 wt %, 70 wt %, 80 wt %, etc. In this embodiment, if the mass fraction of the silicon particles 12 is too low, the active material in the negative electrode active particles 100 is too small, thereby reducing the specific capacity of the negative electrode active particles 100. If the mass fraction of the silicon particles 12 is too high, the porous skeleton 11 is insufficient to support the expansion of the silicon particles 12 during the lithium insertion process of the negative electrode active particles 100, causing the negative electrode active particles 100 to easily rupture, thereby affecting the cycle performance of the battery using the negative electrode active particles 100.

[0215] Optionally, greater than or equal to 90 wt % of the silicon particles 12 are distributed within the plurality of pores 111. It is understood that most of the silicon elements or silicon particles 12 in the negative electrode active particles 100 are distributed within the porous skeleton 11, and the content of silicon particles 12 outside the porous skeleton 11 is less than 10 wt %. Specifically, greater than or equal to 90 wt % of the silicon particles 12 can be distributed within the plurality of pores 111; or greater than or equal to 93 wt % of the silicon particles 12 can be distributed within the plurality of pores 111; or greater than or equal to 95 wt % of the silicon particles 12 can be distributed within the plurality of pores 111; or greater than or equal to 98 wt % of the silicon particles 12 can be distributed within the plurality of pores 111; or 100 wt % of the silicon particles 12 can be distributed within the plurality of pores 111, etc. The silicon particles 12 distributed outside the porous skeleton 11 are not constrained by the porous skeleton 11 when inserting lithium. Therefore, the more silicon particles 12 distributed outside the porous skeleton 11, the higher the expansion rate of the negative electrode active particles 100 when inserting lithium. When greater than or equal to 90wt% of the silicon particles 12 are distributed in the multiple pores 111, the expansion rate of the negative electrode active particles 100 when inserting lithium can be better reduced, thereby improving the cycle capacity retention rate of the negative electrode active particles 100.

[0216] Optionally, in the negative electrode active particles 100, the mass fraction of silicon is in a range of 5 wt% to 95 wt%. Furthermore, in the negative electrode active particles 100, the mass fraction of silicon is in a range of 10 wt% to 85 wt%. Furthermore, in the negative electrode active particles 100, the mass fraction of silicon is in a range of 15 wt% to 80 wt%. Furthermore, in the negative electrode active particles 100, the mass fraction of silicon is in a range of 25 wt% to 70 wt%. Furthermore, in the negative electrode active particles 100, the mass fraction of silicon is in a range of 30 wt% to 60 wt%. Specifically, in the negative electrode active particles 100, the mass fraction of the silicon element can be, but is not limited to, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, etc.

[0217] For detailed descriptions of other aspects such as the negative electrode active particles 100 , the silicon particles 12 , and the silicon element, please refer to the description of the corresponding feature parts of the above embodiment, which will not be repeated here.

[0218] In some embodiments, the porous skeleton 11 includes a carbon element and a second doping element, wherein the second doping element includes at least one of nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, silicon, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the porous skeleton 11, the mass fraction of the carbon element is greater than or equal to 80 wt%.

[0219] Optionally, in the porous skeleton 11 , the mass fraction of the carbon element ranges from 80 wt % to 100 wt %, and the mass fraction of the second doping element ranges from 0 to 20 wt %.

[0220] Specifically, in the porous skeleton 11, the mass fraction of the carbon element can be but is not limited to 80wt%, 82wt%, 84wt%, 86wt%, 88wt%, 90wt%, 92wt%, 94wt%, 86wt%, 98wt%, 100wt%, etc.

[0221] Specifically, in the porous skeleton 11, the mass fraction of the second doping element can be but is not limited to 0wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 18wt%, 20wt%, etc.

[0222] In this embodiment, by doping the second doping element into the porous skeleton 11, the porous skeleton 11 can have higher strength, which can better prevent the negative electrode active particles 100 from breaking during the lithium insertion process, and improve the cycle capacity retention rate of the battery using the negative electrode active particles 100; in addition, the second doping element can improve the conductivity of the porous skeleton 11, and can improve the kinetic performance of the negative electrode active particles 100, thereby improving the kinetic performance of the battery using the negative electrode active particles 100.

[0223] In other embodiments, the porous skeleton 11 may be at least one of a porous carbide (e.g., titanium carbide, TiC), a porous nitride, a porous metal organic compound, etc. Using these compounds as the porous skeleton 11 can better suppress the expansion of the silicon particles 12 during the lithium insertion process of the negative electrode active particles 100.

[0224] Optionally, the porous carbide may be, but is not limited to, at least one of VxC, TixC, SixC, WxC, TaxC, NbxC, ZrxC, BxC, MoxC, FexC, TixAlyC, TixSiyC, etc.

[0225] Optionally, the mass fraction of carbon element in the porous carbide ranges from 5% to 99%; specifically, the mass fraction of carbon element in the porous carbide can be but is not limited to 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%, etc.

[0226] Optionally, the porous nitride may be, but is not limited to, at least one of SixN, BxN, AlxN, TixN, GaxN, ZrxN, VxN, MoxN, WxN, etc.

[0227] Optionally, in the porous nitride, the mass fraction of nitrogen element ranges from 5% to 99%; specifically, in the porous nitride, the mass fraction of nitrogen element can be but is not limited to 5%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 99%, etc.

[0228] Optionally, the porous metal organic compound may be, but is not limited to, at least one of a Zn-based metal organic framework, a Ni-based metal organic framework, a Mn-based metal organic framework, a Cu-based metal organic framework, and the like.

[0229] In some embodiments, the silicon particles 12 meet at least one of the following conditions:

[0230] The silicon particles 12 include silicon element, and the mass fraction of the silicon element in the silicon particles 12 is greater than or equal to 50 wt %;

[0231] The silicon particles 12 also include a third doping element, which includes at least one of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the silicon particles 12, the mass fraction of the third doping element is less than or equal to 50 wt%.

[0232] It is understood that in some embodiments, the silicon particles 12 only include silicon. In other embodiments, the silicon particles 12 include silicon and a third doping element.

[0233] It can be understood that the mass fraction of the silicon element in the silicon particles 12 ranges from 50 wt % to 100 wt %; the mass fraction of the third doping element in the silicon particles 12 ranges from 0 to 50 wt %.

[0234] Specifically, in the silicon particles 12, the mass fraction of the silicon element can be but is not limited to 50wt%, 52wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 85wt%, 90wt%, 95wt%, 100wt%, etc.

[0235] Specifically, in the silicon particles 12, the mass fraction of the third doping element can be but is not limited to 0, 1wt%, 3wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, etc.

[0236] In this embodiment, the doping of oxygen elements can alleviate the expansion of the matrix particles 10 during the lithium insertion process of the negative electrode active particles 100, thereby reducing the expansion rate of the negative electrode active particles 100 and improving the cycle performance of the battery using the negative electrode active particles 100; sulfur, nitrogen, and phosphorus doping can improve the conductivity of the negative electrode active particles 100, thereby improving the kinetic performance of the battery using the negative electrode active particles 100; lithium doping has a lithium replenishing effect, which is beneficial to improving the initial efficiency of the battery using the negative electrode active particles 100; aluminum, magnesium, titanium, sodium, copper, and iron can improve the conductivity of the silicon particles 12, thereby improving the kinetic performance of the battery using the negative electrode active particles 100.

[0237] Optionally, the size of the closed pores 14 is less than or equal to 4 nm. Specifically, the size of the closed pores 14 may be, but is not limited to, less than or equal to 4.0 nm, less than or equal to 3.5 nm, less than or equal to 3 nm, less than or equal to 2.8 nm, less than or equal to 2.5 nm, less than or equal to 2.3 nm, less than or equal to 2 nm, less than or equal to 1.8 nm, less than or equal to 1.5 nm, less than or equal to 1.3 nm, less than or equal to 1 nm, less than or equal to 0.8 nm, less than or equal to 0.5 nm, etc. In this embodiment, if the size of the closed pores 14 is too small, when the negative electrode active particles 100 are used in a battery, during the charge and discharge process of the battery, the closed pores 14 are insufficient to buffer the expansion of the silicon particles 12 during lithium insertion, thereby increasing the expansion rate of the negative electrode active particles 100, increasing the rate of electrolyte consumption, and reducing the cycle capacity retention rate of the battery. If the size of the closed pores 14 is too large, the energy density of the negative electrode active particles 100 is reduced.

[0238] Optionally, the range of the average particle size d3 of the silicon particles 12 is: 0.4nm≤d3≤4nm. Specifically, the average particle size d3 of the silicon particles 12 can be, but is not limited to, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1.0nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm, 2.0nm, 2.3nm, 2.5nm, 2.8nm, 3.0nm, 3.3nm, 3.5nm, 3.8nm, 4.0nm, etc. If the average particle size of the silicon particles 12 is too small, silicon is in an atomic state and cannot form a silicon phase, which reduces the embedding of lithium ions and thereby reduces the specific capacity of the negative electrode active particles 100; if the average particle size of the silicon particles 12 is too large, it is easy to generate Li during the process of lithium embedding of the negative electrode active particles 100. 15 The Si4 crystal phase and phase transition cause higher internal stress and greater volume change in the negative electrode active particles 100, making the negative electrode active particles 100 more susceptible to breakage and reducing the cycle capacity retention rate of the negative electrode active particles 100. When the average particle size d3 of the silicon particles 12 is 0.4nm≤d3≤4nm, the silicon particles 12 are sufficiently small to minimize the pressure on the silicon particles 12 during lithium insertion and removal, thereby reducing the breakage of the negative electrode active particles 100 and ensuring the stability of the silicon structure, thereby further improving the cycle performance of the negative electrode active particles 100.

[0239] Please refer to Figure 1 again. The negative electrode active particles 100 also include a base particle 10 and a plurality of carbon microspheres 20. The plurality of carbon microspheres 20 are distributed on the surface of the base particle 10. The average particle size d1 of the carbon microspheres 20 and the average particle size d2 of the base particle 10 satisfy the relationship: 0.001≤d1 / d2≤0.5.

[0240] Optionally, the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the matrix particles 10 can be, but is not limited to, 0.001, 0.002, 0.004, 0.006, 0.008, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc. If the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the base particles 10 is too small, it means that the size of the carbon microspheres 20 is small, the concave-convex structure on the surface of the negative electrode active particles 100 is not obvious, and the surface is too smooth. When applied to the negative electrode plate, it is not easy to be tightly entangled and connected with the negative electrode binder and the negative electrode conductive agent. In the process of lithium insertion and delithiation of the negative electrode active particles 100, the negative electrode active particles 100 are easily separated from the negative electrode binder and the negative electrode conductive agent, so that the negative electrode active layer of the negative electrode plate is easily pulverized, which reduces the cycle performance of the battery; if the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the base particles 10 is too large, the compaction density of the negative electrode active particles 100 will be reduced, the gram capacity of the negative electrode active particles 100 will be reduced, and the energy density of the battery using the negative electrode active particles 100 will be reduced. When the ratio d1 / d2 of the average particle size d1 of the carbon microspheres 20 to the average particle size d2 of the base particles 10 is between 0.001 and 0.5, a more suitable concave-convex structure can be formed on the surface of the negative electrode active particles 100. When applied to the negative electrode active layer of the negative electrode plate, the negative electrode active particles 100 can be entangled and connected with the binder and negative electrode conductive agent in the negative electrode active layer, thereby reducing the separation of the negative electrode binder and negative electrode conductive agent from the negative electrode active particles 100, which helps to maintain better cycle performance. In addition, the carbon microspheres 20 themselves have good electrical conductivity. The raised areas of the carbon microspheres 20 can also enable the negative electrode active particles 100 to maintain electrical contact with surrounding graphite particles or other negative electrode active particles 100, reducing the polarization phenomenon of the negative electrode plate and facilitating the improvement of the kinetic performance of the negative electrode active particles 100.

[0241] In some embodiments, the average particle size d1 of the carbon microspheres 20 is in the range of 50 nm ≤ d1 ≤ 2000 nm (i.e., 2 μm). Specifically, the average particle size d1 of the carbon microspheres 20 can be, but is not limited to, 50 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 600 nm, 800 nm, 1000 nm, 1200 nm, 1400 nm, 1600 nm, 1800 nm, 2000 nm, etc. If the average particle size of the carbon microspheres 20 is too small, the negative electrode active particles 100 cannot play a network connection role when applied to the negative electrode plate of the battery, so that the negative electrode active particles 100 are easily separated from the negative electrode binder and the negative electrode conductive agent during the process of lithium insertion and delithiation, thereby making the negative electrode active layer of the negative electrode plate easily pulverized, reducing the cycle performance of the battery; if the average particle size d1 of the carbon microspheres 20 is too large, the compaction density of the negative electrode active particles 100 will be reduced, the gram capacity of the negative electrode active particles 100 will be reduced, and the energy density of the battery using the negative electrode active particles 100 will be reduced. When the average particle size of the carbon microspheres 20 is 50nm to 2000nm, the negative electrode active particles 100 can be used in the negative electrode plate of the battery to have a better network connection with the binder and the negative electrode conductive agent, thereby reducing the negative electrode active particles 100 from being easily separated from the negative electrode binder and the negative electrode conductive agent during the process of lithium insertion and delithiation, thereby improving the cycle performance of the battery; in addition, the negative electrode plate can have a more suitable compaction density, thereby increasing the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0242] In some embodiments, the mass fraction of the plurality of carbon microspheres 20 in the negative electrode active particles 100 ranges from 0.05 wt % to 5 wt %. Specifically, the mass fraction of the plurality of carbon microspheres 20 in the negative electrode active particles 100 may be, but is not limited to, 0.05 wt %, 0.08 wt %, 0.1 wt %, 0.2 wt %, 0.4 wt %, 0.6 wt %, 0.8 wt %, 1 wt %, 1.5 wt %, 2 wt %, 2.5 wt %, 3 wt %, 3.5 wt %, 4 wt %, 4.5 wt %, 5 wt %, etc. In the negative electrode active particles 100, if the mass fraction of the multiple carbon microspheres 20 is too low, the number of carbon microspheres 20 is too small or the particle size of the carbon microspheres 20 is too small, which makes it impossible for the negative electrode active particles 100 to play a network connection role when applied to the negative electrode plate of the battery. The negative electrode active particles 100 are easily separated from the negative electrode binder and the negative electrode conductive agent during the process of lithium insertion and delithiation, thereby making the negative electrode active layer of the negative electrode plate easily pulverized, reducing the cycle performance of the battery; if the mass fraction of the carbon microspheres 20 is too large, it means that the particle size of the carbon microspheres 20 is too large, which will reduce the compaction density of the negative electrode active particles 100 and the gram capacity of the negative electrode active particles 100, thereby reducing the energy density of the battery using the negative electrode active particles 100. When the mass fraction of the plurality of carbon microspheres 20 in the negative electrode active particles 100 is in the range of 0.05wt% to 5wt%, the negative electrode active particles 100 can be used in the negative electrode plate of the battery to have a better network connection with the binder and the negative electrode conductive agent, thereby reducing the negative electrode active particles 100 from being easily separated from the negative electrode binder and the negative electrode conductive agent during the process of lithium insertion and delithiation, thereby improving the cycle performance of the battery; in addition, the negative electrode plate can have a more suitable compaction density, thereby improving the gram capacity of the negative electrode active particles 100 and the energy density of the battery.

[0243] In some embodiments, the carbon microspheres 20 include carbon and a first doping element. Doping the carbon microspheres 20 with the first doping element can improve the first efficiency or kinetic performance of the negative electrode active particles 100.

[0244] Optionally, the mass fraction of the carbon element in the carbon microspheres 20 ranges from 50wt% to 100wt%; the first doping element includes at least one of nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; the mass fraction of the first doping element in the carbon microspheres 20 ranges from 0 to 50%.

[0245] In this embodiment, the doping of oxygen elements can alleviate the expansion of the matrix particles 10 during the lithium insertion process of the negative electrode active particles 100, thereby reducing the expansion rate of the negative electrode active particles 100 and improving the cycle performance of the battery using the negative electrode active particles 100; sulfur, nitrogen, and phosphorus doping can improve the conductivity of the negative electrode active particles 100, thereby improving the kinetic performance of the battery using the negative electrode active particles 100; lithium doping has a lithium replenishing effect, which is beneficial to improving the initial efficiency of the battery using the negative electrode active particles 100; aluminum, magnesium, titanium, sodium, copper, and iron can improve the conductivity of the carbon microspheres 20, thereby improving the kinetic performance of the battery using the negative electrode active particles 100.

[0246] Please refer to Figure 2 again. In some embodiments, the negative electrode active particles 100 further include a coating layer 30, which is disposed on the surface of the plurality of carbon microspheres 20. The coating layer 30 includes at least one of a conductive agent and a binder. The coating layer 30 having a conductive agent or a binder is formed on the surface of the carbon microspheres 20. The conductive agent can improve the electronic conductivity of the negative electrode active particles 100. When the negative electrode active particles 100 are made into negative electrode sheets, the electrical connection between the negative electrode active particles 100 and adjacent negative electrode active particles 100 can be increased, thereby improving the dynamic performance of the negative electrode sheet. When the negative electrode active particles 100 are made into negative electrode sheets, the binder can bond adjacent negative electrode active particles 100, reduce the expansion of the negative electrode sheet during the lithium insertion and delithiation process, and improve the cycle performance of the negative electrode sheet.

[0247] For detailed descriptions of other aspects such as the wrapping layer 30 , the conductive agent, and the adhesive, please refer to the descriptions of the corresponding parts above, which will not be repeated here.

[0248] Referring again to FIG. 7 , the present embodiment further provides a method for preparing negative electrode active particles, wherein the negative electrode active particles include matrix particles. The preparation method includes:

[0249] S2011, providing a porous skeleton 11, wherein the porous skeleton 11 has a plurality of pores 111, and the average sphericity of the porous skeleton 11 is greater than or equal to 0.8;

[0250] S2012, introducing a silicon source gas into the porous skeleton 11 to deposit silicon particles 12 in the plurality of pores 111; and

[0251] S2013 , forming a carbon coating layer 13 on the surface of the porous skeleton 11 having the silicon particles 12 to obtain base particles 10 .

[0252] Among them, the base particles 10 include a porous skeleton 11, silicon particles 12 and a carbon coating layer 13; the porous skeleton 11 has a plurality of pores 111; the silicon particles 12 are located in the plurality of pores 111, and there is a gap between the silicon particles 12 and the inner wall of the pore 111; the carbon coating layer 13 is wrapped around the outer periphery of the porous skeleton 11 to seal the gap and form the gap into a closed pore 14.

[0253] The average sphericity of the base particles 10 is greater than or equal to 0.8. The average mass fraction of the silicon particles 12 in the negative electrode active material composed of the plurality of negative electrode active particles 100 is A, and the mass fraction of the silicon particles 12 in greater than or equal to 80% of the negative electrode active particles 100 ranges from A-10 wt% to A+10 wt%.

[0254] For detailed descriptions of other aspects such as S2011, S2012, S2013, etc., please refer to the descriptions of the corresponding parts above and will not be repeated here.

[0255] The preparation method of the negative electrode active particles of this embodiment selects the porous skeleton 11 with an average sphericity greater than or equal to 0.8 as the skeleton, which helps to improve the transmission of silicon source gas in the porous skeleton 11 during silicon deposition, so that the silicon source gas is more evenly deposited in the multiple pores 111 of the porous skeleton 11, so that the silicon particles 12 can be deposited more evenly, and the uniformity of the distribution of silicon particles 12 in the porous skeleton 11 and the uniformity of the size of silicon particles 12 are improved, so that when the negative electrode active particles 100 are embedded in lithium, the expansion of the silicon particles 12 can be better dispersed, and each silicon particle 12 in the porous skeleton 11 has more sufficient expansion space to buffer the expansion of the silicon particles 12, reduce the damage to the negative electrode active particles 100 during the lithium embedding process, and improve the cycle performance of the negative electrode active particles 100. In addition, by ensuring that the mass fraction of the silicon particles 12 in more than 80% of the negative electrode active particles 100 is within the range of ±10wt%, the mass fraction of the silicon particles 12 in each negative electrode active particle 100 is more balanced, so that when the negative electrode active particles 100 are embedded with lithium, the expansion rates of the various negative electrode active particles 100 are closer, thereby avoiding excessively high silicon particle 12 content and excessive expansion rate in some negative electrode active particles 100, thereby ensuring that the negative electrode active particles 100 have a higher cycle capacity retention rate.

[0256] In some embodiments, the step of introducing a silicon source gas into the porous skeleton 11 to deposit silicon particles 12 in the plurality of pores 111 comprises: introducing a silicon source gas at a first temperature T1 of 400° C. ≤ T1 ≤ 700° C. to deposit silicon particles 12 in the plurality of pores 111; wherein the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 111 of the porous skeleton 11 is in the range of 0.05 g / cm 3≤m / V'≤2.0g / cm 3 .

[0257] It should be noted that "the total volume V' of the plurality of pores 111 of the porous skeleton 11" refers to the sum of the volumes of all the pores 111 of the porous skeleton 11 in the reaction system. For example, the total volume V' of the plurality of pores 111 of the porous skeleton 11 = the weight m of the porous skeleton 11 involved in the reaction × the pore volume V of the porous skeleton 11. In other words, V' = mV.

[0258] Optionally, the silicon source gas may include but is not limited to at least one of monosilane, disilane, dichlorosilane, trichlorosilane, and the like.

[0259] Optionally, before the silicon source gas is introduced into the porous skeleton 11 , the silicon source gas may be mixed with the protective gas before being introduced, or the protective gas may be introduced at the same time as the silicon source gas is introduced.

[0260] Optionally, the protective gas may be, but is not limited to, at least one of argon, nitrogen, and the like.

[0261] Specifically, the first temperature T1 can be, but is not limited to, 400°C, 430°C, 450°C, 480°C, 500°C, 530°C, 550°C, 580°C, 600°C, 630°C, 650°C, 680°C, 700°C, etc. If the first temperature T1 is too high, the reaction speed of the silicon source gas will be too fast, and the silicon source gas will not have time to enter the pores 111 of the porous skeleton 11 before it begins to deposit. The deposition of silicon on the surface of the porous skeleton 11 will cause the negative electrode active particles 100 to embed lithium. When silicon expands, it is not restricted by the space of the porous skeleton 11, which increases the expansion rate of the entire negative electrode active particles 100, and the cycle performance of the battery using the negative electrode active particles 100 deteriorates. In addition, when silicon is deposited on the surface, the size of silicon will not be restricted by the size of the pores 111 in the porous skeleton 11, and will continue to grow. Excessive silicon size will result in the generation of Li when embedding lithium. 15 The Si4 phase further deteriorates the cycle performance of the battery using the negative electrode active particles 100 ; if the first temperature T1 is too low, the silicon source gas is difficult to decompose into silicon and deposit, and silicon particles 12 cannot be formed in the pores 111 of the porous skeleton 11 .

[0262] Specifically, the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the plurality of pores 111 of the porous skeleton 11 may be, but is not limited to, 0.05 g / cm 3 , 0.08g / cm 3 , 0.1g / cm 3 , 0.15g / cm 3 , 0.2g / cm 3 , 0.25g / cm3 , 0.3g / cm 3 , 0.4g / cm 3 , 0.5g / cm 3 , 0.6g / cm 3 , 0.8g / cm 3 , 1.0g / cm 3 , 1.2g / cm 3 , 1.4 / cm 3 , 1.6g / cm 3 , 1.8g / cm 3 , 1.9g / cm 3 , 2.0g / cm 3 Etc. If the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 111 of the porous skeleton 11 is too small, the energy density of the negative electrode active particles 100 obtained will be too low; if the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 111 of the porous skeleton 11 is too large, the mass fraction of silicon in the negative electrode active particles 100 obtained will be too high, which will increase the expansion rate of the negative electrode active particles 100. During the lithium insertion process of the negative electrode active particles 100, the porous skeleton 11 is insufficient to support the expansion of the silicon particles 12, making the negative electrode active particles 100 easy to rupture, affecting the cycle performance of the battery using the negative electrode active particles 100. When the ratio m / V' of the mass m of the silicon source gas to the total volume V' of the multiple pores 111 of the porous skeleton 11 is 0.05 g / cm 3 ≤m / V'≤2g / cm 3 When the negative electrode active particles 100 are added, the negative electrode active particles 100 can have a higher energy density and a lower expansion rate, so that the battery using the negative electrode active particles 100 has better cycle performance.

[0263] Optionally, the deposition time t of the silicon particles 12 is in the range of 3h≤t≤100h. Specifically, the deposition time t of the silicon particles 12 can be, but is not limited to, 3h, 5h, 8h, 10h, 15h, 20h, 25h, 30h, 35h, 40h, 50h, 60h, 70h, 80h, 90h, 100h, etc. If the deposition time t of the silicon particles 12 is too long, it is easy for the silicon particles 12 to grow too large, the formed silicon particles 12 are too large, and the size of the silicon phase in the negative electrode active particles 100 is too large, so that the negative electrode active particles 100 are more likely to generate Li when lithium is inserted. 15 Si4 crystal phase, during the formation of the crystal phase, the negative electrode active particles 100 will cause higher internal stress and produce greater volume changes, which will deteriorate the cycle performance of the negative electrode active particles 100; if the deposition time t of the silicon particles 12 is too short, the silicon content in the negative electrode active particles 100 will be reduced, thereby reducing the specific capacity of the negative electrode active particles 100.

[0264] Optionally, forming a carbon coating layer 13 on the surface of the porous skeleton 11 having the silicon particles 12 includes: forming a carbon coating layer 13 on the surface of the porous skeleton 11 having the silicon particles 12 in a first organic carbon source at a second temperature T2 in the range of 500°C≤T2≤900°C.

[0265] Optionally, a first organic carbon source is added to the porous skeleton 11 having silicon particles 12 , and chemical vapor deposition (ie, carbon deposition) is performed at 500° C. to 900° C. to form a carbon coating layer 13 on the surface of the porous skeleton 11 having silicon particles 12 .

[0266] Optionally, the first organic carbon source includes a first organic gas and a first carrier gas; the first organic gas may be, but is not limited to, at least one of acetylene and methane, etc. The first carrier gas may be, but is not limited to, at least one of nitrogen and argon, etc.

[0267] Optionally, the volume concentration V1 of the first organic gas in the first organic carbon source ranges from 1% to 50%. Specifically, the volume concentration V1 of the first organic gas in the first organic carbon source can be, but is not limited to, 1%, 3%, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, etc. If the volume concentration V1 of the first organic gas in the first organic carbon source is too low, the rate of formation of the carbon coating layer 13 is reduced, thereby reducing production efficiency. If the volume concentration V1 of the first organic gas in the first organic carbon source is too high, the carbon deposition rate is too fast, resulting in uneven carbon deposition and failure to effectively enclose the silicon particles 12 in the pores 111 of the porous framework 11.

[0268] Optionally, the second temperature T2 may be, but is not limited to, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, etc. If the second temperature T2 is too low, the first organic carbon source is difficult to reduce; if the second temperature T2 is too high, carbon deposition is too rapid, which may result in uneven formation of the carbon coating layer 13 and difficulty in completely enclosing the silicon particles 12 within the pores 111 of the porous skeleton 11. This increases side reactions of the silicon particles 12 and reduces the cycle performance of the negative electrode active particles 100. Furthermore, if the second temperature T2 is too high, inert silicon carbide is easily generated, which reduces the energy density of the negative electrode active particles 100.

[0269] Optionally, the deposition time of the carbon coating layer 13 can be 1 minute to 3 hours, for example, 1 minute, 20 minutes, 30 minutes, 45 minutes, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc. If the deposition time of the carbon coating layer 13 is too short, the first organic carbon source is difficult to be reduced, and the carbon coating layer 13 is difficult to completely cover the porous skeleton 11, so that part of the silicon particles 12 is exposed, thereby increasing the side reaction between the negative electrode active particles 100 and the electrolyte; if the deposition time of the carbon coating layer 13 is too long, inert silicon carbide is easily generated, and the formed carbon coating layer 13 is too thick, which reduces the energy density of the negative electrode active particles 100.

[0270] Furthermore, the deposition time of the carbon coating layer 13 may be 1 hour to 3 hours, so that the formed carbon coating layer 13 can better seal the pores 111 or gaps and make the negative electrode active particles 100 have a higher energy density.

[0271] For detailed descriptions of the porous skeleton 11 , silicon particles 12 , carbon coating layer 13 , pores 111 , gaps, and closed pores 14 , please refer to the descriptions of the corresponding parts of the above embodiments, which will not be repeated here.

[0272] In some embodiments, in S202, the negative electrode active particles also include a plurality of carbon microspheres 20, and the plurality of carbon microspheres 20 are distributed on the surface of the base particles 10. The preparation method also includes: placing the base particles 10 in a second organic carbon source, at a third temperature T3 in the range of 300°C≤T3≤900°C, to form a plurality of carbon microspheres 20 on the surface of the base particles 10.

[0273] In some embodiments, the second organic carbon source can be an organic carbon source solution, wherein the organic carbon source solution includes at least one of glucose solution, fructose solution, lactose solution, citric acid solution, sucrose solution, and the like.

[0274] In other embodiments, the second organic carbon source includes a second organic gas and a second carrier gas. Optionally, the second organic gas may be, but is not limited to, at least one of acetylene and methane. The second carrier gas may be, but is not limited to, at least one of nitrogen and argon.

[0275] Furthermore, when the second organic carbon source includes a second organic gas and a second carrier gas, the third temperature T3 at which the carbon microspheres 20 are deposited is in the range of 500° C. ≤ T3 ≤ 900° C. When the second organic carbon source includes an organic carbon source solution, the third temperature T3 at which the carbon microspheres 20 are formed is in the range of 300° C. ≤ T3 ≤ 900° C., i.e., the organic carbon source is carbonized at the third temperature to form the carbon microspheres 20.

[0276] Alternatively, the third temperature T3 may be, but is not limited to, 300° C., 350° C., 400° C., 450° C., 500° C., 550° C., 600° C., 650° C., 700° C., 750° C., 800° C., 850° C., 900° C., etc. If the third temperature T3 is too low, the second organic carbon source may be difficult to reduce or carbonize to form the carbon microspheres 20. Furthermore, if the third temperature T3 is too low and the second organic carbon source includes a second organic gas, a coating layer may easily form after the second organic carbon source is deposited, making it difficult to form the carbon microspheres 20. If the third temperature T3 is too high, inert silicon carbide may be easily generated, thereby reducing the energy density of the negative electrode active particles 100.

[0277] Optionally, the volume concentration V2 of the second organic gas in the second organic carbon source ranges from 5% to 100%. Specifically, the volume concentration V2 of the second organic gas in the second organic carbon source can be, but is not limited to, 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, 100%, etc. If the volume concentration V2 of the second organic gas in the second organic carbon source is too low, the carbon deposition rate is reduced, making it difficult to form unevenly deposited carbon microspheres 20 on the surface of the carbon coating layer 13.

[0278] Optionally, the deposition time of the carbon microspheres 20 can be 1 min to 3 h, for example, 1 min, 20 min, 30 min, 45 min, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, etc. If the deposition time of the carbon microspheres 20 is too short, the first organic carbon source is difficult to be reduced, and the carbon microspheres 20 are difficult to completely cover the porous skeleton 11, so that some silicon particles 12 are exposed, thereby increasing the side reaction between the negative electrode active particles 100 and the electrolyte; if the deposition time of the carbon microspheres 20 is too long, inert silicon carbide is easily generated, and the formed carbon microspheres 20 are too thick, which reduces the energy density of the negative electrode active particles 100.

[0279] Furthermore, the deposition time of the carbon microspheres 20 can be 1 hour to 3 hours, so that the formed carbon microspheres 20 can better close the pores 111 or gaps and make the negative electrode active particles 100 have a higher energy density.

[0280] In some embodiments, the first organic carbon source includes a first organic gas and a first carrier gas, the second organic carbon source includes a second organic gas and a second carrier gas, the second temperature T2 is lower than the third temperature T3, and the volume concentration of the first organic gas in the first organic carbon source is lower than the volume concentration of the second organic gas in the second organic carbon source.

[0281] In this embodiment, by making the second temperature T2 lower than the third temperature T3 and making the volume concentration of the first organic gas in the first organic carbon source lower than the volume concentration of the second organic gas in the second organic carbon source, the carbon deposition rate is slower when the first organic carbon source is used for chemical vapor deposition, so that the carbon deposition can be more uniform, and the pores 111 in the porous skeleton 11 can be better sealed, so that the carbon coating layer 13 can be better formed on the surface of the porous skeleton 11. When the second organic carbon source is used for chemical vapor deposition, the carbon deposition rate is faster, so that carbon microspheres 20 can be formed on the surface of the carbon coating layer 13, so that the surface of the negative active particles 100 forms a concave-convex structure. When applied to the negative active layer of the negative electrode sheet, it can be entangled and connected with the binder and negative conductive agent in the negative active layer, thereby reducing the situation where the negative binder and negative conductive agent are separated from the negative active particles 100 and lose the conductive network, which helps to maintain better cycle performance. In addition, the carbon microspheres 20 themselves have good conductivity. The raised positions of the carbon microspheres 20 can also enable the negative electrode active particles 100 to maintain electrical contact with the surrounding graphite particles or other negative electrode active particles 100, reducing the polarization phenomenon of the negative electrode plate, which is beneficial to improving the kinetic performance of the negative electrode active particles 100.

[0282] In some embodiments, the range of the difference T3-T2 between the third temperature T3 and the second temperature T2 is: 20° C. ≤ T3-T2 ≤ 250° C.;

[0283] Alternatively, a difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source is in the range of: 5%≤V2-V1≤99%;

[0284] Alternatively, the range of the difference T3-T2 between the third temperature T3 and the second temperature T2 is: 20°C ≤ T3-T2 ≤ 250°C, and the range of the difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source is: 5% ≤ V2-V1 ≤ 99%.

[0285] Specifically, the difference T3-T2 between the third temperature T3 and the second temperature T2 can be, but is not limited to, 20°C, 30°C, 50°C, 80°C, 100°C, 130°C, 150°C, 180°C, 200°C, 230°C, 250°C, etc. If the difference T3-T2 between the third temperature T3 and the second temperature T2 is too small, when both the third temperature T3 and the second temperature T2 are low, carbon microspheres 20 may not be formed during deposition. If both the third temperature T3 and the second temperature T2 are high, the carbon coating layer 13 may be deposited at a high carbon deposition rate, resulting in an uneven carbon coating layer 13 and difficulty in completely enclosing the silicon particles 12 within the pores 111 of the porous skeleton 11. This increases side reactions of the silicon particles 12 and reduces the cycle performance of the negative electrode active particles 100. Furthermore, when the second temperature T2 is too high, inert silicon carbide may be generated, reducing the energy density of the negative electrode active particles 100. When the difference T3-T2 between the third temperature T3 and the second temperature T2 is too large, inert silicon carbide is easily generated during the deposition of the silicon particles 12, which reduces the energy density of the negative electrode active particles 100.

[0286] Specifically, the difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source can be but is not limited to 5%, 7%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, 99%, etc. If the difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic carbon source is too small, it is possible that the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source are both high. When the carbon coating layer 13 is deposited, the deposition rate of the carbon coating layer 13 is too high, thereby reducing the uniformity of the deposition of the carbon coating layer 13 and reducing the cycle performance of the negative active particles 100. Or it is possible that the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic carbon source are both low, thereby reducing the production efficiency of the negative active particles 100; if the difference V2-V1 between the volume concentration V2 of the second organic carbon source and the volume concentration V1 of the first organic carbon source is too large, it is possible that the volume concentration V1 of the first organic gas in the first organic carbon source is too low, thereby reducing the production efficiency of the negative active particles 100.

[0287] Please refer to Figure 8. The embodiment of the present application also provides a negative electrode plate 400, which includes a negative electrode current collector 410 and a negative electrode active layer 420. The negative electrode active layer 420 is arranged on the surface of the negative electrode current collector 410. The negative electrode active layer 420 includes the negative electrode active particles 100 described in the embodiment of the present application or the negative electrode active particles 100 prepared by the preparation method of the negative electrode active particles 100 described in the embodiment of the present application.

[0288] Optionally, the negative electrode active layer 420 may be disposed on one surface or multiple surfaces of the negative electrode current collector 410 .

[0289] Optionally, the negative electrode current collector 410 may be, but is not limited to, a copper sheet.

[0290] Optionally, the negative electrode active layer 420 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 negative electrode binder are uniformly dispersed.

[0291] Optionally, the negative electrode conductive agent may be, but is not limited to, conductive carbon black (SP for short), acetylene black, carbon nanotubes, carbon fibers, and graphite.

[0292] Optionally, the negative electrode binder may be, but is not limited to, at least one of polyacrylic acid (PAA), polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyvinylether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene butadiene rubber (SBR).

[0293] Optionally, the mass fraction of the negative electrode binder in the negative electrode active layer 420 ranges from 2 wt% to 4 wt%. Specifically, the mass fraction of the negative electrode binder in the negative electrode active layer 420 may be, but is not limited to, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, etc. If the mass fraction of the negative electrode binder is too low, the negative electrode active layer 420 may easily pulverize or slag; if the mass fraction of the negative electrode binder is too high, the energy density of the negative electrode sheet 400 may be reduced.

[0294] 9 and 10 , an embodiment of the present application further provides a battery 500, comprising: an electrolyte, a positive electrode sheet 510, a diaphragm 530, and a negative electrode sheet 400 of an embodiment of the present application, wherein the positive electrode sheet 510 is at least partially immersed in the electrolyte; the diaphragm 530 is located on one side of the positive electrode sheet 510 and is at least partially immersed in the electrolyte; and the negative electrode sheet 400 is arranged on a side of the diaphragm 530 away from the positive electrode sheet 510 and is at least partially immersed in the electrolyte.

[0295] It can be understood that the positive electrode sheet 510 , the separator 530 and the negative electrode sheet 400 are stacked in sequence.

[0296] The battery 500 of the embodiment of the present application can be, but is not limited to, a lithium-ion secondary battery 500, a lithium-ion primary battery 500, a lithium-sulfur battery 500, a sodium-lithium-ion battery 500, a sodium-ion battery 500, or a magnesium-ion battery 500.

[0297] 11 , optionally, the positive electrode sheet 510 includes a positive electrode current collector 511 and a positive electrode active layer 513 covering the surface of the positive electrode current collector 511. It is understood that the positive electrode active layer 513 may cover one surface or two opposite surfaces of the positive electrode current collector 511.

[0298] The positive electrode current collector 511 may be, but is not limited to, an aluminum sheet.

[0299] Optionally, the positive electrode active layer 513 includes a positive electrode active material, a positive electrode conductor, and a positive electrode binder.

[0300] Optionally, the positive electrode active material may be, but is not limited to, at least one of lithium iron phosphate, lithium cobalt oxide, and the like.

[0301] Optionally, the positive electrode conductive agent may be, but is not limited to, at least one of conductive carbon black, acetylene black, carbon nanotubes, carbon fibers, graphene, and the like.

[0302] Optionally, the positive electrode binder may be, but is not limited to, at least one of polyvinylidene fluoride (PVDF), polyamide (PA), polyacrylonitrile (PAN), polyacrylate, polyvinylether, polymethyl methacrylate (PMMA), polyhexafluoropropylene, and styrene butadiene rubber (SBR).

[0303] Optionally, the mass fraction of the positive electrode binder in the positive electrode active layer 513 ranges from 2 wt% to 4 wt%. Specifically, the mass fraction of the positive electrode binder in the positive electrode active layer 513 may be, but is not limited to, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, etc. If the mass fraction of the positive electrode binder is too low, the positive electrode active layer 513 may easily pulverize or slag; if the mass fraction of the positive electrode binder is too high, the energy density of the positive electrode sheet 510 may be reduced.

[0304] Optionally, the electrolyte includes an electrolyte salt, an organic solvent and a film-forming additive.

[0305] Optionally, the electrolyte salt is a lithium salt, which may include but is not limited to at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(oxalatoborate) (LiBOB), LiODFP, lithium difluorooxalatoborate (LiODFB), lithium difluorophosphate (LiPO2F2), lithium trifluoromethanesulfonate (CF3SO3Li), etc.

[0306] Optionally, in the electrolyte, the molar concentration M of the lithium salt is in the range of 0.7 mol / L≤M≤1.4 mol / L. In the electrolyte, the molar concentration M of the lithium salt may be, but is not limited to, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 1.0 mol / L, 1.1 mol / L, 1.2 mol / L, 1.3 mol / L, 1.4 mol / L, and the like. In the electrolyte, if the molar concentration M of the lithium salt is too small, the concentration of free ions in the electrolyte is too small, which reduces the conductivity of the electrolyte and thus reduces the kinetic performance of the battery; in the electrolyte, if the molar concentration M of the lithium salt is too large, it is easy for a portion of the electrolyte salt to remain undissociated, and the viscosity of the electrolyte will increase, which in turn reduces the conductivity of the electrolyte and also reduces the kinetic performance of the battery. In the electrolyte, when the molar concentration M of the lithium salt is in the range of 0.7 mol / L≤M≤1.4 mol / L, the electrolyte can have a higher conductivity, thereby enabling the battery to have better kinetic performance.

[0307] Optionally, the organic solvent includes at least one of a cyclic carbonate and a chain carbonate. Cyclic carbonate has a high dielectric constant and high ionic conductivity, and can form a stable SEI film on the surface of the negative electrode plate 400, but its viscosity is relatively high. Chain carbonate has a lower viscosity than cyclic carbonate, better electrochemical stability, and can improve the low-temperature performance of the electrolyte. Therefore, when a mixed solvent of cyclic carbonate and chain carbonate is used, the electrolyte can have a more suitable viscosity and low-temperature stability, and the battery 500 using the electrolyte can also form a better film.

[0308] Optionally, the cyclic carbonate may include but is not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), etc. The dielectric constant of ethylene carbonate is much greater than that of propylene carbonate, and ethylene carbonate can better promote the formation of SEI film.

[0309] Optionally, the chain carbonate may include but is not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and the like.

[0310] Optionally, the organic solvent includes at least one of a cyclic carbonate and a chain carbonate. Cyclic carbonate has a high dielectric constant and high ionic conductivity, and can form a stable SEI film on the surface of the negative electrode plate 400, but its viscosity is relatively high. Chain carbonate has a lower viscosity than cyclic carbonate, better electrochemical stability, and can improve the low-temperature performance of the electrolyte. Therefore, when a mixed solvent of cyclic carbonate and chain carbonate is used, the electrolyte can have a more suitable viscosity and low-temperature stability, and the battery 500 using the electrolyte can also form a better film.

[0311] Optionally, the cyclic carbonate may include but is not limited to at least one of ethylene carbonate (EC), propylene carbonate (PC), etc. The dielectric constant of ethylene carbonate is much greater than that of propylene carbonate, and ethylene carbonate can better promote the formation of SEI film.

[0312] Optionally, the chain carbonate may include but is not limited to at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and the like.

[0313] Optionally, the film-forming additive includes at least one of fluoroethylene carbonate (FEC), vinyl sulfate (PST), vinylene carbonate (VC), vinyl ethylene carbonate (VEC), sulfur tris(trimethylsilyl) phosphate, tris(trimethylsilyl) borate, adiponitrile, succinonitrile, and 1,3,6-hexanetrinitrile.

[0314] Optionally, the mass fraction of the film-forming additive ranges from 1.5% to 3%. Specifically, the mass fraction of the film-forming additive may be, but is not limited to, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3%, etc. The film-forming additive may be used to promote the formation of an interfacial film on at least one of the positive electrode sheet 510 and the negative electrode sheet 400 and maintain the stability of the interfacial film.

[0315] Optionally, the diaphragm 530 may be, but is not limited to, at least one of a polypropylene film (PP), a polyethylene film (PE), a ceramic film, etc. Optionally, the thickness of the diaphragm 530 is 14 μm to 18 μm. Specifically, the thickness of the diaphragm 530 may be, but is not limited to, 14 μm, 14.5 μm, 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, and 18 μm.

[0316] In some embodiments, the battery 500 further includes a housing 550 and an end cap assembly 570. The housing 550 and the end cap assembly 570 enclose a receiving space (not shown) for accommodating the electrolyte, the positive electrode sheet 510, the separator 530, and the negative electrode sheet 400. The end cap assembly 570 includes a positive electrode post (not shown) and a negative electrode post (not shown). The positive electrode post is electrically connected to the positive electrode sheet 510, and the negative electrode post is electrically connected to the negative electrode sheet 400. The positive electrode post and the negative electrode post are used to electrically connect the battery 500 to an electrical device or other battery 500.

[0317] It can be understood that the battery 500 described in this embodiment is merely a form of the battery 500 used by the negative electrode plate 400, and should not be understood as a limitation on the battery 500 provided in this application, nor should it be understood as a limitation on the negative electrode plate 400 provided in each embodiment of this application.

[0318] The base particles 10 and the battery 500 of the present application are further described below through specific embodiments.

[0319] Example 1

[0320] The base particles 10 of this embodiment are prepared by the following steps:

[0321] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.97, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.7 nm, and the pore volume of the porous skeleton 11 was 0.85 cm 3 / g;

[0322] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) for 24 h. The total mass m of the introduced silane was 1000 g.

[0323] 3) Formation of the carbon coating layer 13 : heating to 650° C. and introducing acetylene gas (first organic gas) for 2 hours. After cooling, the resulting black powder is the base particle 10 .

[0324] A scanning electron microscope (SEM) image was taken of the base particles 10 prepared in Example 1, and the obtained SEM image is shown in FIG12 .

[0325] The base particles 10 prepared in Example 1 were subjected to an energy dispersive spectrometer (EDS) scanning test, and the obtained EDS scanning images are shown in FIG. 13 and FIG. 14 .

[0326] Example 2

[0327] The base particles 10 of this embodiment are prepared by the following steps:

[0328] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.85, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.9 nm, and the pore volume of the porous skeleton 11 was 0.7 cm 3 / g;

[0329] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) for 24 h. The total mass m of silane introduced was 900 g.

[0330] 3) Formation of the carbon coating layer 13 : heating to 650° C. and introducing acetylene gas (first organic gas) for 2 hours. After cooling, the resulting black powder is the base particle 10 .

[0331] Example 3

[0332] The base particles 10 of this embodiment are prepared by the following steps:

[0333] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.97, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.7 nm, and the pore volume of the porous skeleton 11 was 0.85 cm 3 / g;

[0334] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) for 24 h. The total mass m of silane introduced was 1200 g.

[0335] 3) Formation of the carbon coating layer 13 : heating to 650° C. and introducing acetylene gas (first organic gas) for 2 hours. After cooling, the resulting black powder is the base particle 10 .

[0336] Example 4

[0337] The base particles 10 of this embodiment are prepared by the following steps:

[0338] 1) 1000 g of spherical titanium carbide as a porous skeleton 11 is placed in a vapor deposition furnace. The average sphericity of the porous skeleton 11 is 0.9, the porous skeleton 11 comprises a plurality of pores 111, the average size of the pores 111 is 1.8 nm, and the pore volume of the porous skeleton 11 is 0.9 cm 3 / g;

[0339] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) for 24 h. The total mass m of the introduced silane was 1000 g.

[0340] 3) Formation of the carbon coating layer 13 : heating to 650° C. and introducing acetylene gas (first organic gas) for 2 hours. After cooling, the resulting black powder is the base particle 10 .

[0341] Comparative Example 1

[0342] The base particles 10 of this comparative example were prepared by the following steps:

[0343] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.67, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.8 nm, and the pore volume of the porous skeleton 11 was 0.85 cm 3 / g;

[0344] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) for 6 h. The total mass m of the introduced silane was 1000 g.

[0345] 3) Formation of the carbon coating layer 13 : heating to 650° C. and introducing acetylene gas (first organic gas) for 2 hours. After cooling, the resulting black powder is the base particle 10 .

[0346] Comparative Example 2

[0347] The base particles 10 of this comparative example were prepared by the following steps:

[0348] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.97, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.7 nm, and the pore volume of the porous skeleton 11 was 0.85 cm 3 / g;

[0349] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) for 24 h. The total mass m of silane introduced was 2000 g.

[0350] 3) Formation of the carbon coating layer 13 : heating to 650° C. and introducing acetylene gas (first organic gas) for 2 hours. After cooling, the resulting black powder is the base particle 10 .

[0351] It should be noted that the base particles 10 of the present application can be directly used as negative electrode active materials and applied to the negative electrode sheet 400 .

[0352] The following tests were performed on the base particles 10 obtained in Examples 1 to 4 and Comparative Examples 1 and 2:

[0353] 1) Ia / Ib Measurement Method: X-ray powder diffraction (XRD) was performed on the base particles 10 in each Example and Comparative Example using CuKα radiation at a wavelength of 0.154 nm to obtain X-ray diffraction patterns for each Example and Comparative Example. Ia and Ib were obtained from the X-ray diffraction patterns, and Ia / Ib was calculated. The Ia / Ib ratios for Examples 1 to 4 and Comparative Examples 1 and 2 are shown in Table 1 below.

[0354] 2) Measurement of the average particle size d3 of the silicon particles 12:

[0355] The base particles 10 in each embodiment and comparative example were heated to 700°C for 2 hours under an inert atmosphere (N2, Ar, vacuum, etc.), and then cooled to room temperature. XRD testing was performed using CuKα rays with a wavelength of 0.154 nm. The X-ray diffraction patterns of the heat-treated base particles 10 of each embodiment and comparative example were measured. The half-width at half maximum (FWHM) of the diffraction peak of Si(111) near 2θ=28.4° in the X-ray diffraction pattern was used to determine the average particle size d3=7.852 / (FWHM*cosθ) of the silicon particles 12 by the Scherrer method. The d3 of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 1 below.

[0356] 3) Preparation of button half-cell 500: The base particles 10 are mixed with conductive carbon black (SP), carbon nanotubes (CNT), and polyacrylic acid (PAA) in a mass ratio of 80:8:2:10 to form a slurry. The slurry is coated on copper foil (i.e., the negative electrode current collector), vacuum dried, and roll-pressed to obtain a negative electrode sheet 400. The negative electrode sheet 400 is then assembled into a button half-cell 500 using a lithium sheet as a counter electrode.

[0357] 4) The button half-cell 500 was subjected to capacity division and cycle testing: discharged at a discharge rate of 0.1C to 5 mV, allowed to stand for 5 min, then discharged at a discharge rate of 0.05C to 5 mV, allowed to stand for 5 min, then discharged at a discharge rate of 0.02C to 5 mV, allowed to stand for 10 min, and charged at 0.1C to 1.5 V. The cycle was repeated 50 times, and the cycle capacity retention rate after 50 cycles was calculated. The 50 cycle capacity retention rates of the button half-cell 500 composed of the base particles 10 of Examples 1 to 4 and Comparative Examples 1 to 2 are shown in Table 2 below.

[0358] 5) The matrix particles 10 of Examples 1-4 and Comparative Examples 1-2 were mixed with graphite, PAA, and CNT in a mass ratio of 10:87:2.8:0.2 to form a slurry. The slurry was then applied to the negative electrode current collector, dried at 100°C, and roll-pressed with a pressure of 5t to produce a negative electrode plate 400. 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 roll-pressed to produce a positive electrode plate. The negative electrode plate 400, the positive electrode plate, and the separator were fabricated into a wound battery 500. The battery 500 was then encapsulated with aluminum-plastic film, dried, injected, formed, re-encapsulated, and capacity divided. The battery 500 was then subjected to a 25°C cycling test. The cycle capacity retention and thickness expansion rate of the battery 500 formed from the matrix particles 10 of Examples 1-4 and Comparative Examples 1-2 after 400 cycles are shown in Table 3 below.

[0359] 6) Calculation of the thickness expansion rate of the battery 500: Thickness expansion rate of the battery 500 = (thickness of the battery 500 after n cycles - initial thickness of the battery 500) / initial thickness of the battery 500 × 100%.

[0360] Table 1

[0361] Table 2

[0362] Table 3

[0363] As shown in Figure 12, the base particles 10 of Example 1 of the present application have good sphericity. As shown in Figures 13 and 14, the distribution of silicon particles 12 (blue dots in Figure 13) in the base particles 10 prepared in Example 1 is very uniform, and the silicon particles 12 are mainly distributed in the pores 111 of the porous skeleton 11. The silicon particles 12 are relatively small in size.

[0364] The test data for each embodiment and comparative example in Tables 1 and 2 show that when the sphericity of the porous skeleton 11 is higher, the average particle size of the silicon particles 12 deposited in the porous skeleton 11 is smaller, and in the negative electrode active material composed of multiple base particles 10, the distribution of the mass fraction of the silicon particles 12 in each base particle 10 is narrower, and the mass fraction of the silicon particles 12 in each base particle 10 is more similar. Consequently, the coin cell 500 produced using this base particle 10 has a higher cycle capacity retention rate. The test data in Table 3 show that when the sphericity of the porous skeleton 11 is higher, the average particle size of the silicon particles 12 is smaller, and in the negative electrode active material composed of multiple base particles 10, the distribution of the mass fraction of the silicon particles 12 in each base particle 10 is narrower, the battery 500 produced using the base particle 10 has a higher cycle capacity retention rate and a lower expansion rate. Furthermore, the thickness expansion rate of the battery 500 produced using the base particles 10 produced in this application is less than or equal to 4.6% after 400 cycles.

[0365] It can be seen from the test data of Example 1 and Comparative Example 2 that when silicon deposition is carried out, when the total mass of silane is too high, the size of the silicon particles 12 in the obtained base particles 10 increases, and the distribution of the mass fraction of the silicon particles 12 in each base particle 10 becomes wider, so that the expansion rates of different base particles 10 when lithium is inserted are different, which increases the expansion rate of the base particles 10 when lithium is inserted and reduces the cycle capacity retention rate of the base particles 10.

[0366] The Ia / Ib of the base particles 10 of Examples 1 to 4 are all between 0.5 and 0.95, and the button half-cells 500 made using the base particles 10 of each embodiment all have a high cycle capacity retention rate, and their cycle capacity retention rates are all above 95.8%. In addition, the base particles 10 of each embodiment have a high specific capacity. The first lithium insertion specific capacity of the base particles 10 of each embodiment is greater than or equal to 1773 mAh / g, and the first lithium removal specific capacity of the base particles 10 of each embodiment is greater than or equal to 1627 mAh / g. This shows that the base particles 10 of the present application have a high lithium insertion specific capacity, and these specific capacities have high reversibility (i.e., they have a high lithium removal specific capacity). It can be seen from the test data of Comparative Examples 1 and 2 that when the Ia / Ib of the base particles 10 is less than 0.5, the cycle capacity retention rate of the button half-cell 500 made from the base particles 10 is greatly reduced. This indicates that when the Ia / Ib of the base particle 10 is between 0.5 and 0.95, the base particle 10 has a higher cycle capacity retention rate and can maintain a higher specific capacity.

[0367] The test data in Tables 1 and 2 show that when the average particle size D1 of the silicon particles 12 in the base particles 10 of Examples 1 to 4 is less than 2 nm, the button-type half-cells 500 produced from these base particles 10 all exhibit high cycle capacity retention rates, with cycle capacity retention rates exceeding 95.8%. Furthermore, the base particles 10 of each example exhibit high specific capacities, with the initial lithium insertion capacity of the base particles 10 of each example being greater than or equal to 1773 mAh / g, and the initial lithium removal capacity of the base particles 10 of each example being greater than or equal to 1627 mAh / g. The test data from Comparative Examples 1 and 2 show that when the average particle size D1 of the silicon particles 12 in the base particles 10 is greater than 2 nm, the cycle capacity retention rate of the button-type half-cells 500 produced from these base particles 10 is significantly reduced. This indicates that when the average particle size D1 of the silicon particles 12 in the base particles 10 is less than 2 nm, the base particles 10 exhibit higher cycle capacity retention rates and can maintain a high specific capacity.

[0368] The negative electrode active particles 100 and the battery 500 of the present application are further described below through specific examples.

[0369] Example 5

[0370] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0371] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.97, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.7 nm, and the pore volume of the porous skeleton 11 was 0.85 cm 3 / g;

[0372] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) and reaction for 24 hours;

[0373] 3) Formation of the carbon coating layer 13: heating to 650° C. and introducing a mixture of acetylene (first organic gas) and nitrogen (first carrier gas) as a first organic carbon source, wherein the volume concentration V1 of acetylene is 10%, and reacting for 1 hour to obtain the base particles 10;

[0374] 4) Formation of carbon microspheres 20: The base particles 10 are heated to 700°C, and a mixture of acetylene (second organic gas) and nitrogen (second carrier gas) is introduced as a second organic carbon source, wherein the volume concentration V1 of acetylene is 50%. The reaction is carried out for 2 hours to obtain negative electrode active particles 100.

[0375] Example 6

[0376] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0377] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.97, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.7 nm, and the pore volume of the porous skeleton 11 was 0.85 cm 3 / g;

[0378] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) and reaction for 24 hours;

[0379] 3) Formation of the carbon coating layer 13: heating to 650° C. and introducing a mixture of acetylene (first organic gas) and nitrogen (first carrier gas) as a first organic carbon source, wherein the volume concentration V1 of acetylene is 10%, and reacting for 1 hour to obtain the base particles 10;

[0380] 4) Formation of carbon microspheres 20: The base particles 10 were mixed with a glucose solution having a mass concentration of 50 wt%, heated to 100° C. and dried for 1 h; and then heated to 700° C. in a nitrogen atmosphere and carbonized for 1 h to obtain negative electrode active particles 100.

[0381] Example 7

[0382] The negative electrode active particles 100 of this embodiment are prepared by the following steps:

[0383] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.92, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.8 nm, and the pore volume of the porous skeleton 11 was 0.7 cm 3 / g;

[0384] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 530° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) and reaction for 24 hours;

[0385] 3) Formation of the carbon coating layer 13: heating to 650° C. and introducing a mixture of acetylene (first organic gas) and nitrogen (first carrier gas) as a first organic carbon source, wherein the volume concentration V1 of acetylene is 10%, and reacting for 1 hour to obtain the base particles 10;

[0386] 4) Formation of carbon microspheres 20: The base particles 10 were heated to 700° C. and a mixture of acetylene (second organic gas) and nitrogen (second carrier gas) was introduced as the second organic carbon source, wherein the volume concentration V1 of acetylene was 50%, and the reaction was carried out for 2 hours;

[0387] 5) Formation of the coating layer 30: The powder in 4) is mixed with a carbon nanotube (conductive agent) dispersion (the mass ratio of the powder to the carbon nanotube is 100:0.5), and dried to obtain the negative electrode active particles 100.

[0388] Comparative Example 3

[0389] The negative electrode active particles 100 of this comparative example were prepared by the following steps:

[0390] 1) 1000 g of spherical porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.97, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.7 nm, and the pore volume of the porous skeleton 11 was 0.85 cm 3 / g;

[0391] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) and reaction for 24 hours;

[0392] 3) Formation of the carbon coating layer 13: Heat to 650°C and introduce a mixed gas of acetylene (first organic gas) / nitrogen (first carrier gas) as the first organic carbon source, wherein the volume concentration V1 of acetylene is 10%, react for 1 hour, and obtain the base particles 10 as the negative electrode active particles 100.

[0393] Comparative Example 4

[0394] The negative electrode active particles 100 of this comparative example were prepared by the following steps:

[0395] 1) 1000 g of irregular porous carbon was placed in a vapor deposition furnace as a porous skeleton 11. The average sphericity of the porous skeleton 11 was 0.59, the porous skeleton 11 included a plurality of pores 111, the average size of the pores 111 was 1.8 nm, and the pore volume of the porous skeleton 11 was 0.7 cm 3 / g;

[0396] 2) Deposition of silicon particles 12: nitrogen was introduced and heated to 500° C., followed by introduction of a mixed gas of silane and nitrogen (protective gas) and reaction for 24 hours;

[0397] 3) Formation of the carbon coating layer 13: heating to 650° C. and introducing a mixture of acetylene (first organic gas) and nitrogen (first carrier gas) as a first organic carbon source, wherein the volume concentration V1 of acetylene is 10%, and reacting for 1 hour to obtain the base particles 10;

[0398] 4) Formation of carbon microspheres 20: The base particles 10 are heated to 700°C, and a mixture of acetylene (second organic gas) and nitrogen (second carrier gas) is introduced as a second organic carbon source, wherein the volume concentration V1 of acetylene is 50%. The reaction is carried out for 2 hours to obtain negative electrode active particles 100.

[0399] The preparation, capacity division and cycle testing methods of the button half-cell 500 are as described in the corresponding parts above and will not be repeated here.

[0400] Various parameters of the negative electrode active particles 100 of Examples 5 to 7, Comparative Examples 3 and 4, and various performance tests of the button-type half-cells 500 composed of the components are shown in Tables 4 and 5 below.

[0401] Table 4

[0402] Table 5

[0403] A scanning electron microscope image of the negative electrode active particles 100 prepared in Example 6 is shown in FIG15 . FIG15 shows that a plurality of carbon microspheres 20 are formed at intervals on the surface of the base particles 10. FIG15 shows that the method of the present application can produce negative electrode active particles 100 having a concave-convex surface structure.

[0404] From the test data of Examples 5 to 7 and Comparative Examples 3 to 4, it can be seen that the battery 500 made from the negative electrode active particles 100 of the present application has a higher initial efficiency and a higher cycle capacity retention rate. The 100 cycle capacity retention rate of the battery 500 made from the negative electrode active particles 100 of the present application is greater than or equal to 96.8%.

[0405] The test data of Example 5 and Comparative Example 3 show that compared to the negative electrode active particles 100 without carbon microspheres 20 on the surface (Comparative Example 3), the base particles 10 of Example 5 having multiple carbon microspheres 20 on the surface, the battery 500 made from the negative electrode active particles 100 of Example 5 exhibited a higher capacity retention rate and a higher initial efficiency after 100 cycles. This indicates that the formation of carbon microspheres 20 on the surface of the base particles 10 is beneficial for improving the cycle performance of the negative electrode active particles 100 and achieving a higher initial efficiency.

[0406] It can be seen from the test data of Example 5 and Comparative Example 4 that, when other conditions are similar, the sphericity of the porous skeleton 11 of Comparative Example 4 is much lower than the sphericity of the porous skeleton 11 of Example 5; compared with the negative electrode active particles 100 of Comparative Example 4, the battery 500 made from the negative electrode active particles 100 of Example 5 has higher first efficiency and higher cycle capacity retention rate.

[0407] The negative electrode active particles 100 of Example 7 have an additional wrapping layer 30 (the wrapping layer 30 includes a conductive agent) compared to the negative electrode active particles 100 of Example 6. Compared to Example 6, the battery 500 made from the negative electrode active particles 100 of Example 7 has a higher initial efficiency and a higher cycle capacity retention rate.

[0408] Please refer to Figures 16 and 17. The embodiment of the present application further provides an electronic device 600, which includes a device body 610 and the battery 500 described in the embodiment of the present application. The battery 500 is used to power the device body 610.

[0409] The electronic device 600 of the embodiment of the present application can be, but is not limited to, a portable electronic device 600 such as a mobile phone, a tablet computer, a laptop computer, a desktop computer, a smart toy, smart glasses, a smart bracelet, a smart watch, an e-reader, a game console, or a toy.

[0410] For a detailed description of the battery 500 , please refer to the description of the corresponding part of the above embodiment, which will not be repeated here.

[0411] It can be understood that the electronic device 600 described in this embodiment is merely a form of electronic device 600 used by the battery 500, and should not be understood as a limitation on the electronic device 600 provided in this application, nor should it be understood as a limitation on the battery 500 provided in each embodiment of this application.

[0412] Optionally, the device body 610 of the embodiment of the present application further includes a display screen 611, a middle frame 613, and a housing 615. The housing 615 is disposed opposite the display screen 611, the middle frame 613 is located between the display screen 611 and the housing 615, and the sidewalls of the middle frame 613 are exposed to the display screen 611 and the housing 615. The middle frame 613 and the housing 615 enclose an accommodating space, which is used to accommodate the battery 500. The display screen 611 is electrically connected to the battery 500, and the battery 500 provides power for the display screen 611.

[0413] Optionally, the display screen 611 may be, but is not limited to, one or more of a liquid crystal display screen, a light emitting diode display screen (LED display screen), a micro light emitting diode display screen (Micro LED display screen), a sub-millimeter light emitting diode display screen (Mini LED display screen), an organic light emitting diode display screen (OLED display screen), etc.

[0414] Please also refer to Figure 18. Optionally, the device body 610 of the present application further includes a processor 617 and a memory 616. The processor 617 and the memory 616 are disposed in the accommodation space. The processor 617 is electrically connected to the battery 500, the display screen 611, and the memory 616, respectively. The processor 617 is configured to control the display screen 611 for display, and the memory 616 is configured to store program codes required for the processor 617 to operate, program codes required to control the display screen 611, and display content of the display screen 611.

[0415] Optionally, the processor 617 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 617 is used to execute various types of digital storage instructions, such as software or firmware programs stored in the memory 616, which enables the computing device to provide a wide variety of services.

[0416] Optionally, the memory 616 may include volatile memory, such as random access memory (RAM); the memory 616 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 616 may also include a combination of the above types of memory 616.

[0417] In some embodiments, the device body 610 of the present embodiment further includes a camera module 618, which is disposed in the accommodation space. The camera module 618 is electrically connected to the processor 617 and the battery 500, respectively, for taking pictures under the control of the processor 617. The battery 500 also provides power to the camera module 618.

[0418] Optionally, the housing 615 has a light-transmitting portion (not shown), and the camera module 618 can capture images through the light-transmitting portion on the housing 615. That is, the camera module 618 in this embodiment is a rear-facing camera module 618. It is understood that in other embodiments, the light-transmitting portion can be provided on the display screen 611, that is, the camera module 618 is a front-facing camera module 618. In the schematic diagram of this embodiment, the light-transmitting portion is illustrated as an opening. In other embodiments, the light-transmitting portion may not be an opening, but may be made of a light-transmitting material, such as plastic or glass.

[0419] 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.

[0420] 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, wherein: The negative electrode active particles include: base particles; and A plurality of carbon microspheres are distributed on the surface of the matrix particles, and an average particle size d1 of the carbon microspheres and an average particle size d2 of the matrix particles satisfy the relationship: 0.001≤d1 / d2≤0.

5.

2. The negative electrode active particle according to claim 1, wherein The average particle size d1 of the carbon microspheres is in the range of 50 nm ≤ d1 ≤ 2000 nm.

3. The negative electrode active particle according to claim 1, wherein In the negative electrode active particles, the mass fraction of the plurality of carbon microspheres ranges from 0.05 wt % to 5 wt %.

4. The negative electrode active particle according to claim 1, wherein The carbon microspheres include carbon and a first doping element, wherein the mass fraction of the carbon element in the carbon microspheres ranges from 50wt% to 100wt%; the first doping element includes at least one of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; and the mass fraction of the first doping element in the carbon microspheres ranges from 0 to 50%.

5. The negative electrode active particle according to any one of claims 1 to 4, wherein: The negative electrode active particles further include a wrapping layer, which is disposed on the surfaces of the plurality of carbon microspheres and includes at least one of a conductive agent and a binder.

6. The negative electrode active particle according to any one of claims 1 to 4, wherein: The matrix particles include: A porous skeleton having a plurality of pores; silicon particles, the silicon particles being located in the plurality of pores, with gaps between the silicon particles and inner walls of the pores; and A carbon coating layer, wherein the carbon coating layer is wrapped around the periphery of the porous skeleton to seal the gaps and form closed pores in the gaps; Wherein, the average sphericity of the matrix particles is greater than or equal to 0.

8.

7. The negative electrode active particle according to claim 6, wherein The average mass fraction of the silicon particles in the negative electrode active material composed of the plurality of negative electrode active particles is A, which is greater than or equal to 80%. The mass fraction of the silicon particles in the negative electrode active particles ranges from A-10wt% to A+10wt%.

8. The negative electrode active particle according to claim 6, wherein In the negative electrode active particles, the mass fraction of the silicon particles ranges from 20 wt % to 80 wt %, and greater than or equal to 90 wt % of the silicon particles are distributed in the plurality of pores.

9. The negative electrode active particle according to claim 6, wherein The closed pores and the silicon particles satisfy the relationship 0.5≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° in the X-ray diffraction pattern of the negative electrode active particles, and 2θ is the intensity of the diffraction peak of Si(111) in the range of 2θ from 28.2° to 28.5° in the X-ray diffraction pattern of the negative electrode active particles; and 2θ is the diffraction angle.

10. The negative electrode active particle according to claim 6, wherein In the negative electrode active particles, the mass fraction of silicon element ranges from 5 wt % to 95 wt %.

11. The negative electrode active particle according to claim 6, wherein The porous skeleton includes a carbon element and a second doping element, wherein the second doping element includes at least one of nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, silicon, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the porous skeleton, the mass fraction of the carbon element is greater than or equal to 80 wt%; or, The porous skeleton is at least one of porous carbide, porous nitride, and porous metal organic compound.

12. The negative electrode active particle according to claim 7, wherein The silicon particles satisfy at least one of the following conditions: The silicon particles include silicon element, and the mass fraction of the silicon element in the silicon particles is greater than or equal to 50 wt %; and The silicon particles also include a third doping element, which includes at least one of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the silicon particles, the mass fraction of the third doping element is less than or equal to 50wt%.

13. The negative electrode active particle according to claim 6, wherein The size of the closed pores is less than or equal to 4 nm; the range of the average particle size d3 of the silicon particles is: 0.4 nm≤d3≤4 nm.

14. A method for preparing negative electrode active particles, wherein: include: providing substrate particles; as well as A plurality of carbon microspheres are formed on the surface of the base particles, wherein an average particle size d1 of the carbon microspheres and an average particle size d2 of the base particles satisfy the relationship: 0.001≤d1 / d2≤0.

5.

15. The method for preparing negative electrode active particles according to claim 14, wherein: The providing of matrix particles comprises: Providing a porous skeleton, wherein the porous skeleton has a plurality of pores, and the average sphericity of the porous skeleton is greater than or equal to 0.8; introducing a silicon source gas into the porous skeleton to deposit silicon particles in the plurality of pores; and A carbon coating layer is formed on the surface of the porous skeleton having the silicon particles to obtain base particles; wherein the base particles include a porous skeleton, silicon particles and a carbon coating layer; the silicon particles are located in the plurality of pores, and there are gaps between the silicon particles and the inner walls of the pores; the carbon coating layer is wrapped around the periphery of the porous skeleton to seal the gaps and form closed pores in the gaps.

16. The method for preparing negative electrode active particles according to claim 15, wherein: The step of introducing a silicon source gas into the porous skeleton to deposit silicon particles in the plurality of pores comprises: At a first temperature T1 of 400°C ≤ T1 ≤ 700°C, silicon source gas is introduced to deposit silicon particles in the plurality of pores; wherein the ratio m of the mass of the silicon source gas to the total volume V' of the plurality of pores of the porous skeleton is in the range of 0.05 g / cm 3 ≤m / V'≤2.0g / cm 3 .

17. The method for preparing negative electrode active particles according to claim 15, wherein: The step of forming a carbon coating layer on the surface of the porous skeleton having the silicon particles comprises: In the first organic carbon source, at a second temperature T2 in the range of 500° C. ≤ T2 ≤ 900° C., a carbon coating layer is formed on the surface of the porous skeleton having the silicon particles.

18. The method for preparing negative electrode active particles according to claim 17, wherein: The forming of a plurality of carbon microspheres on the surface of the base particles comprises: The base particles are placed in a second organic carbon source at a third temperature T3 in the range of 300° C. ≤ T3 ≤ 900° C. to form a plurality of carbon microspheres on the surface of the base particles.

19. The method for preparing negative electrode active particles according to claim 18, wherein: The first organic carbon source includes a first organic gas and a first carrier gas, the second organic carbon source includes a second organic gas and a second carrier gas, the second temperature T2 is lower than the third temperature T3, and the volume concentration of the first organic gas in the first organic carbon source is lower than the volume concentration of the second organic gas in the second organic carbon source.

20. The method for preparing negative electrode active particles according to claim 19, wherein: The range of the difference T3-T2 between the third temperature T3 and the second temperature T2 is: 20°C ≤ T3-T2 ≤ 250°C; Alternatively, a difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source is in the range of: 5%≤V2-V1≤99%; Alternatively, the range of the difference T3-T2 between the third temperature T3 and the second temperature T2 is: 20°C ≤ T3-T2 ≤ 250°C, and the range of the difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source is: 5% ≤ V2-V1 ≤ 99%.

21. A negative electrode active particle, wherein: The negative electrode active particles include matrix particles, and the matrix particles include: A porous skeleton having a plurality of pores; silicon particles, the silicon particles being located in the plurality of pores, with gaps between the silicon particles and inner walls of the pores; and A carbon coating layer, wherein the carbon coating layer is wrapped around the periphery of the porous skeleton to seal the gaps and form closed pores in the gaps; Among them, the average sphericity of the base particles is greater than or equal to 0.8, the average mass fraction of the silicon particles in the negative electrode active material composed of multiple negative electrode active particles is A, greater than or equal to 80%, and the mass fraction of the silicon particles in the negative electrode active particles ranges from A-10wt% to A+10wt%.

22. The negative electrode active particle according to claim 21, wherein The closed pores and the silicon particles satisfy the relationship 0.5≤Ia / Ib≤0.95, wherein Ia is the minimum value of the diffraction intensity in the range of 8.8° to 22° in the X-ray diffraction pattern of the negative electrode active particles, and 2θ is the intensity of the diffraction peak of Si(111) in the range of 2θ from 28.2° to 28.5° in the X-ray diffraction pattern of the negative electrode active particles; and 2θ is the diffraction angle.

23. The negative electrode active particle according to claim 21, wherein In the negative electrode active particles, the mass fraction of the silicon particles ranges from 20 wt % to 80 wt %, and greater than or equal to 90 wt % of the silicon particles are distributed in the plurality of pores; In the negative electrode active particles, the mass fraction of silicon element ranges from 5 wt % to 95 wt %.

24. The negative electrode active particle according to claim 21, wherein The porous skeleton includes a carbon element and a second doping element, wherein the second doping element includes at least one of nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, silicon, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the porous skeleton, the mass fraction of the carbon element is greater than or equal to 80 wt%; or, The porous skeleton is at least one of porous carbide, porous nitride, and porous metal organic compound.

25. The negative electrode active particle according to claim 21, wherein The silicon particles satisfy at least one of the following conditions: The silicon particles include silicon element, and the mass fraction of the silicon element in the silicon particles is greater than or equal to 50 wt %; and The silicon particles also include a third doping element, which includes at least one of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; in the silicon particles, the mass fraction of the third doping element is less than or equal to 50wt%.

26. The negative electrode active particle according to any one of claims 21 to 25, wherein The size of the closed pores is less than or equal to 4 nm; the range of the average particle size d3 of the silicon particles is: 0.4 nm≤d3≤4 nm.

27. The negative electrode active particle according to any one of claims 21 to 25, wherein The negative electrode active particles further include: A plurality of carbon microspheres are distributed on the surface of the matrix particles, and an average particle size d1 of the carbon microspheres and an average particle size d2 of the matrix particles satisfy the relationship: 0.001≤d1 / d2≤0.

5.

28. The negative electrode active particle according to claim 27, wherein The carbon microspheres meet at least one of the following conditions: The average particle size d1 of the carbon microspheres is in the range of 50 nm ≤ d1 ≤ 2000 nm; and In the negative electrode active particles, the mass fraction of the plurality of carbon microspheres ranges from 0.05 wt % to 5 wt %.

29. The negative electrode active particle according to claim 27, wherein The carbon microspheres include carbon and a first doping element, wherein the mass fraction of the carbon element in the carbon microspheres ranges from 50wt% to 100wt%; the first doping element includes at least one of carbon, nitrogen, oxygen, fluorine, chlorine, phosphorus, sulfur, titanium, zirconium, vanadium, molybdenum, tungsten, aluminum, and iron; and the mass fraction of the first doping element in the carbon microspheres ranges from 0 to 50%.

30. The negative electrode active particle according to claim 27, wherein The negative electrode active particles further include a wrapping layer, which is disposed on the surfaces of the plurality of carbon microspheres and includes at least one of a conductive agent and a binder.

31. A method for preparing negative electrode active particles, wherein: The negative electrode active particles include matrix particles, and the preparation method includes: Providing a porous skeleton, wherein the porous skeleton has a plurality of pores, and the average sphericity of the porous skeleton is greater than or equal to 0.8; introducing a silicon source gas into the porous skeleton to deposit silicon particles in the plurality of pores; and A carbon coating layer is formed on the surface of the porous skeleton having the silicon particles to obtain base particles; wherein the base particles include a porous skeleton, silicon particles and a carbon coating layer; the silicon particles are located in the multiple pores, and there is a gap between the silicon particles and the inner wall of the pore; the carbon coating layer is wrapped around the periphery of the porous skeleton to seal the gap and form the gap into a closed hole; the average sphericity of the base particles is greater than or equal to 0.8, the average mass fraction of the silicon particles in the negative electrode active material composed of the multiple negative electrode active particles is A, which is greater than or equal to 80%, and the mass fraction of the silicon particles in the negative electrode active particles ranges from A-10wt% to A+10wt%.

32. The method for preparing negative electrode active particles according to claim 31, wherein: The step of introducing a silicon source gas into the porous skeleton to deposit silicon particles in the plurality of pores comprises: At a first temperature T1 of 400°C ≤ T1 ≤ 700°C, silicon source gas is introduced to deposit silicon particles in the plurality of pores; wherein the ratio m of the mass of the silicon source gas to the total volume V' of the plurality of pores of the porous skeleton is in the range of 0.05 g / cm 3 ≤m / V'≤2.0g / cm 3 ; The step of forming a carbon coating layer on the surface of the porous skeleton having the silicon particles comprises: In the first organic carbon source, at a second temperature T2 in the range of 500° C. ≤ T2 ≤ 900° C., a carbon coating layer is formed on the surface of the porous skeleton having the silicon particles.

33. The method for preparing negative electrode active particles according to claim 32, wherein: The negative electrode active particles further include a plurality of carbon microspheres, which are distributed on the surface of the matrix particles. The preparation method further includes: The base particles are placed in a second organic carbon source at a third temperature T3 in the range of 300° C. ≤ T3 ≤ 900° C. to form a plurality of carbon microspheres on the surface of the base particles.

34. The method for preparing negative electrode active particles according to claim 33, wherein: The first organic carbon source includes a first organic gas and a first carrier gas, the second organic carbon source includes a second organic gas and a second carrier gas, the second temperature T2 is lower than the third temperature T3, and the volume concentration of the first organic gas in the first organic carbon source is lower than the volume concentration of the second organic gas in the second organic carbon source.

35. The method for preparing negative electrode active particles according to claim 34, wherein: The range of the difference T3-T2 between the third temperature T3 and the second temperature T2 is: 20°C ≤ T3-T2 ≤ 250°C; Alternatively, a difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source is in the range of: 5%≤V2-V1≤99%; Alternatively, the range of the difference T3-T2 between the third temperature T3 and the second temperature T2 is: 20°C ≤ T3-T2 ≤ 250°C, and the range of the difference V2-V1 between the volume concentration V2 of the second organic gas in the second organic carbon source and the volume concentration V1 of the first organic gas in the first organic carbon source is: 5% ≤ V2-V1 ≤ 99%.

36. A negative electrode plate, wherein: include: negative electrode current collector; as well as A negative electrode active layer is provided on the surface of the negative electrode current collector, and the negative electrode active layer comprises the negative electrode active particles according to any one of claims 1 to 13 and 21 to 30 or the negative electrode active particles prepared by the preparation method of the negative electrode active particles according to any one of claims 14 to 20 and 31 to 35.

37. A battery, wherein: 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 sheet and at least partially immersed in the electrolyte, and The negative electrode plate according to claim 36 is arranged on the side of the diaphragm away from the positive electrode plate and is at least partially immersed in the electrolyte.

38. An electronic device, wherein: include: Equipment body; as well as The battery according to claim 37 is used to power the device body.

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