Negative electrode material, preparation method thereof, negative electrode sheet, electrode assembly, and battery

Abstract

The application discloses a negative electrode material and a preparation method thereof, a negative electrode sheet, an electrode assembly and a battery. The negative electrode material comprises a silicon-based material, the silicon-based material comprises solid granular silicon-based material with a ring structure and micro-powder silicon-based material for filling the hollow ring of the solid granular silicon-based material and / or the gap between the solid granular silicon-based materials. The technical scheme of the application can improve the capacity performance of the negative electrode material by using the silicon-based material. Meanwhile, the hollows penetrating through the solid granular silicon-based material and / or the gaps between the solid granular silicon-based materials can provide a buffer space when the silicon-based material expands in volume due to lithium intercalation, so that the stress generated by the expansion of the silicon-based material is more easily dissipated, the volume expansion effect of the silicon-based material is relieved, the outward expansion of the negative electrode material is reduced, the silicon-based material is inhibited from peeling off from the current collector, and the cycle stability of the battery is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a negative electrode material, a preparation method thereof, a negative electrode sheet, an electrode assembly, a battery and an electric device. BACKGROUND

[0002] Lithium ion batteries are widely used due to their high energy density and long cycle life. The performance of the negative electrode material is one of the key factors affecting the overall performance of the lithium ion battery. Graphite is the most commonly used negative electrode material for lithium ion batteries. However, the theoretical specific capacity of graphite is only 372 mAh / g, which cannot meet the requirements of high energy density for various consumer electronic devices, especially energy storage devices and electric vehicles. Silicon-based materials have attracted attention due to their high theoretical specific capacity and abundant reserves. However, the volume of silicon-based materials tends to expand during the cycle process, leading to electrode pulverization and even peeling off from the current collector, resulting in rapid capacity decay of the battery. SUMMARY

[0003] In view of the above problems, the present application provides a negative electrode material, a preparation method thereof, a negative electrode sheet, an electrode assembly, a battery and an electric device, aiming to alleviate the problem of expansion of silicon-based negative electrode materials.

[0004] In a first aspect, the embodiments of the present application provide a negative electrode material, comprising a silicon-based material, wherein the silicon-based material comprises a solid particle silicon-based material with a ring structure and a micro-powder silicon-based material for filling the hollow ring of the solid particle silicon-based material and / or the gap between the solid particle silicon-based materials.

[0005] By designing the negative electrode material to include a silicon-based material with a higher theoretical specific capacity, and the silicon-based material including a solid particle silicon-based material and a micro-powder silicon-based material, wherein the solid particle silicon-based material has a ring structure, i.e. the solid particle silicon-based material has a shape similar to a "donut", and the solid particle silicon-based material has a hollow formed therein, and the micro-powder silicon-based material fills the hollow of the solid particle silicon-based material and / or the gap between the solid particle silicon-based materials. By using a silicon-based material, the capacity performance of the negative electrode material can be improved, and by using the hollows in the solid particle silicon-based material and / or the gaps between the solid particle silicon-based materials, when the silicon-based material expands in volume due to lithium intercalation, the hollows and / or gaps can provide a buffer space, making it easier for the stress generated by the expansion of the silicon-based material to dissipate, alleviating the volume expansion effect of the silicon-based material, reducing the outward expansion of the negative electrode material, inhibiting the peeling of the silicon-based material from the current collector, and improving the cycle stability of the battery.

[0006] In some embodiments, the chemical formula of the silicon-based material is SiO x , wherein 0≤x<2.

[0007] By setting the silicon-based material as elemental silicon and / or silicon suboxide with a high theoretical specific capacity, it is beneficial to improve the theoretical specific capacity of the anode material, thereby increasing the energy density of the battery.

[0008] In some embodiments, 0.9 ≤ x ≤ 1.1.

[0009] By setting x to 0.9 to 1.1, i.e., the silicon-based material is silicon suboxide, and the oxygen content in silicon suboxide is close to the silicon content, silicon suboxide in this ratio range not only has a much higher specific capacity than graphite, but also does not undergo drastic volume expansion during charging like elemental silicon. At the same time, it can also ensure that enough elemental silicon is generated during lithiation, ensuring conductivity and effective capacity.

[0010] In some embodiments, the outer diameter of the solid particulate silicon-based material is 6 μm to 9 μm, and the inner diameter is 1 μm to 3 μm.

[0011] An excessively large outer diameter will increase the volume of the solid particulate silicon-based material, while an excessively small inner diameter will increase the wall thickness of the ring-shaped solid particulate silicon-based material, both of which are detrimental to the diffusion and migration of lithium ions within the solid particulate silicon-based material. By setting the outer diameter of the solid particulate silicon-based material to 6μm to 9μm and the inner diameter to 1μm to 3μm, the anode material prepared within this range exhibits better rate performance.

[0012] In some embodiments, the specific surface area of ​​the solid particulate silicon-based material is 2.4 m². 2 / g~3.6m 2 / g.

[0013] In some embodiments, the specific surface area of ​​the negative electrode material is 3m². 2 / g~5m 2 / g.

[0014] Increasing the specific surface area of ​​solid silicon-based materials or anode materials can enhance the number of reactive sites, accelerate interfacial reactions, and improve battery kinetics. However, this increased surface area also increases the area of ​​the SEI film, leading to increased lithium-ion consumption. By setting the specific surface area within a certain range, the electrochemical performance of the anode material is optimized.

[0015] In some embodiments, the SiO x It is an amorphous material, and the surface of the solid particulate silicon-based material is coated with a carbon layer.

[0016] Due to SiO x As an amorphous material, the disordered atomic distribution results in low electronic conductivity. By coating the surface of solid particulate silicon-based materials with a carbon layer, the conductivity of the solid particulate silicon-based materials can be improved, thereby enhancing the rate performance of the anode material.

[0017] In some embodiments, the solid particulate silicon-based material is in a spherical or spheroid shape.

[0018] By setting the solid particulate silicon-based material in a spherical or spheroid shape, it is beneficial for the solid particulate silicon-based material to form voids between each other, which can provide a buffer space when the solid particulate silicon-based material expands, so that the stress generated by the expansion of the solid particulate silicon-based material is more easily dissipated. In some embodiments, the median particle size of the fine silicon-based material is 0.1-0.5 μm.

[0019] Generally, the smaller the median particle size of the fine silicon-based material, the more the fine silicon-based material can be filled into the hollow rings of the solid particulate silicon-based material and the voids between the solid particulate silicon-based materials, thereby improving the capacity of the negative electrode material. However, the smaller the median particle size of the fine silicon-based material, the lower the porosity of the negative electrode material layer when the negative electrode material layer is formed, thereby causing the expansion rate of the negative electrode material to increase, and the manufacturing cost of the fine silicon-based material to increase. Generally, the larger the median particle size of the fine silicon-based material, the less the fine silicon-based material can be filled into the hollow rings of the solid particulate silicon-based material and the voids between the solid particulate silicon-based materials, and the larger the median particle size of the fine silicon-based material, the more difficult it is for lithium ions to diffuse in the fine silicon-based material, thereby reducing the rate performance of the negative electrode material. Therefore, by reasonably setting the median particle size of the fine silicon-based material, the capacity, expansion, and rate performance of the negative electrode material can be simultaneously considered.

[0020] In some embodiments, the mass ratio of the solid particulate silicon-based material to the fine silicon-based material is 4: (1-2).

[0021] By setting the mass ratio of the solid particulate silicon-based material to the fine silicon-based material to be 4: (1-2), within this range, the volume of the solid particulate silicon-based material and the fine silicon-based material expanded when intercalating lithium can be just absorbed by the hollows of the solid particulate silicon-based material and the voids between the solid particulate silicon-based materials, preventing the negative electrode material from excessively expanding outward.

[0022] In some embodiments, the negative electrode material further comprises graphite, and the median particle size of the graphite is greater than the outer diameter of the solid particulate silicon-based material.

[0023] Since the graphite has a small self-volume expansion during the charging and discharging process, and the median particle size of the graphite is larger than the outer diameter of the solid particle silicon-based material, by adding the graphite into the solid particle silicon-based material with a ring structure, it is beneficial to build a gap between the graphite and the solid particle silicon-based material to relieve the expansion of the silicon-based material and slow down the outward expansion of the negative electrode material; meanwhile, since the main component of the solid particle silicon-based material with a ring structure is elemental silicon and / or silicon oxide, the conductivity is poor, by adding the graphite into the negative electrode material, a conductive network is built in the negative electrode material by using the good conductivity of the graphite, and better contact between the solid particle silicon-based material and the current collector and between the solid particle silicon-based materials is ensured.

[0024] In some embodiments, the median particle size of the graphite is 10 μm to 20 μm.

[0025] As the negative electrode active material, if the median particle size of the graphite is too large, the rate of the negative electrode material will be reduced, and if the median particle size of the graphite is too small, the porosity of the negative electrode material will be reduced, and the expansion stress of the silicon-based material cannot be well buffered. By setting the median particle size of the graphite to be 10 μm to 20 μm, the anti-expansion property and the rate performance of the negative electrode material prepared in this range are better.

[0026] In some embodiments, the theoretical mass specific capacity of the negative electrode material is 1100 mAh / g to 1400 mAh / g.

[0027] By setting the theoretical mass specific capacity of the negative electrode material to be 1100 mAh / g to 1400 mAh / g, compared with the traditional graphite negative electrode material, the theoretical mass specific capacity of the negative electrode material is improved, and compared with the elemental negative electrode material, the volume expansion rate of the negative electrode material is well inhibited.

[0028] In a second aspect, the embodiments of the present application provide a preparation method of a negative electrode material, comprising:

[0029] providing a solid particle silicon-based material with a ring structure and a micro-powder silicon-based material;

[0030] mixing and processing the solid particle silicon-based material and the micro-powder silicon-based material, so that the micro-powder silicon-based material is filled in the hollow ring of the solid particle silicon-based material and / or in the gap between the solid particle silicon-based materials.

[0031] By mixing the solid particle silicon-based material and the micro-powder silicon-based material, the micro-powder silicon-based material fills in the cavities of the solid particle silicon-based material and / or the gaps between the solid particle silicon-based material. When the silicon-based material expands in volume after lithium insertion, the cavities and / or gaps can provide a buffer space, so that the stress generated by the expansion of the silicon-based material is more easily dissipated, the volume expansion effect of the silicon-based material is alleviated, the outward expansion of the negative electrode material is reduced, the peeling of the silicon-based material from the current collector is inhibited, and the cycle stability of the battery is improved.

[0032] In some embodiments, the method further comprises preparing the solid particle silicon-based material, comprising: providing a silicon-based material initial material;

[0033] The silicon-based material initial material is crushed to obtain crushed particles;

[0034] The crushed particles are prepared into a suspension solution, and the suspension solution is subjected to spray drying treatment to obtain a solid particle silicon-based material with a ring structure.

[0035] By crushing the silicon-based material initial material and then preparing it into a suspension solution for spray drying treatment, a solid particle silicon-based material with a ring structure is obtained, which is simple and easy to operate.

[0036] In some embodiments, the spray drying treatment comprises atomizing the suspension solution and then injecting it into a hot air stream for drying, the temperature of the drying air being 90-110°C, and the solution flow rate being 80-120 L / min.

[0037] By atomizing the suspension solution prepared from the crushed particles into small droplets and then injecting it into a hot air stream, and controlling the temperature of the drying air to be 90-110°C and the solution flow rate to be 80-120 L / min, the crushed particles wrapped in the small droplets are deformed by rapid vaporization and drying in the hot air, thereby preparing a solid particle silicon-based material with a ring structure, i.e., a solid particle silicon-based material with a donut structure. This preparation method is simple and has a considerable yield.

[0038] In some embodiments, the method of preparing the negative electrode material further comprises a pre-lithiation treatment of the solid particle silicon-based material.

[0039] The first efficiency of the negative electrode material can be improved to 92% by the pre-lithiation treatment.

[0040] In some embodiments, the method of preparing the negative electrode material further comprises a step of carbon-coating the solid particle silicon-based material with a ring structure.

[0041] The carbon layer is coated on the surface of the solid particle silicon-based material through carbon coating treatment. Compared with silicon material, the carbon material has better conductivity. The carbon layer coated on the solid particle silicon-based material can effectively improve the conductivity of the negative electrode material and optimize the rate performance of the negative electrode material.

[0042] In a third aspect, the embodiments of the present application provide a negative electrode sheet, comprising a negative electrode current collector and a negative electrode material layer arranged on at least one side of the negative electrode current collector, wherein the negative electrode material layer comprises the negative electrode material provided in the first aspect of the embodiments of the present application or the negative electrode material prepared by the preparation method provided in the second aspect of the embodiments of the present application.

[0043] By using the solid particle silicon-based material with a ring structure in the negative electrode material layer, and the solid particle silicon-based material comprising a silicon-based material with a higher theoretical specific capacity, the theoretical specific capacity of the negative electrode material can be improved by using the silicon-based material. Meanwhile, by using the hollows penetrating through the solid particle silicon-based material, the hollows can provide a buffer space when the silicon-based material expands in volume due to lithium intercalation, so that the stress generated by the expansion of the silicon-based material is more easily dissipated, the volume expansion effect of the silicon-based material is alleviated, the silicon-based material is inhibited from peeling off from the current collector, and the cycle stability of the battery is improved.

[0044] In some embodiments, the porosity of the negative electrode material layer gradually increases from the inside to the surface along the thickness direction of the negative electrode material layer.

[0045] Generally, during the lithiation process of the negative electrode material layer, the electrolyte first wets the negative electrode material, and then the lithium ions in the electrolyte gradually migrate and diffuse into the inside of the negative electrode material layer and react with the active material of the negative electrode material layer to generate lithium compounds. The closer to the outer surface of the negative electrode material layer, the higher the concentration of lithium ions, and the more lithium compounds are generated. Therefore, the expansion of the negative electrode material is more serious. By setting the negative electrode material layer to have a porosity gradually increasing from the inside to the surface, the overall stress distribution of the negative electrode material layer during charging can be uniform, and the local stress of the negative electrode material layer is inhibited from being too large to cause the negative electrode material layer to fall off. At the same time, the pores in the negative electrode material layer can also act as channels for the diffusion of lithium ions. The porosity of the negative electrode material layer gradually increases from the inside to the surface, so that a gradient mass transfer can be formed on the negative electrode material layer, which is beneficial to the rapid diffusion of lithium ions into the inside of the negative electrode material layer and improves the rate performance of the battery.

[0046] In some embodiments, the negative electrode material is located on the surface layer of the negative electrode material layer.

[0047] By arranging the above negative electrode material with the surface layer of the negative electrode material layer, the negative electrode material is beneficial to contact with the electrolyte. Since the above negative electrode material comprises the solid particle silicon-based material and the micro-powder silicon-based material, the hollows on the solid particle silicon-based material can serve as channels for the electrolyte to infiltrate the negative electrode material, and the micro-powder silicon-based material has more active sites, which can accelerate the interface reaction and improve the rate performance of the negative electrode sheet.

[0048] In a fourth aspect, an embodiment of the present application provides an electrode assembly, comprising:

[0049] The negative electrode sheet provided in the third aspect of the embodiments of the present application;

[0050] A separator film covering at least one side of the negative electrode sheet.

[0051] By using the negative electrode sheet provided in the third aspect of the embodiments of the present application, the energy density of the electrode assembly is improved, and the expansion rate of the negative electrode sheet is effectively inhibited.

[0052] In a fifth aspect, an embodiment of the present application provides a battery comprising the electrode assembly provided in the fourth aspect of the embodiments of the present application.

[0053] By using the electrode assembly provided in the fourth aspect of the embodiments of the present application, the energy density of the battery is improved, and the expansion rate of the negative electrode sheet is effectively inhibited.

[0054] In a sixth aspect, an embodiment of the present application provides a power utilization device comprising the battery provided in the fifth aspect of the embodiments of the present application.

[0055] By using the battery provided in the fifth aspect of the embodiments of the present application, the working stability and endurance of the power utilization device are improved.

[0056] The above description is only a summary of the technical solutions of the present application. In order to enable one skilled in the art to better understand the technical means of the present application, the following specific embodiments of the present application are implemented in accordance with the content of the description, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the following specific embodiments of the present application are implemented. BRIEF DESCRIPTION OF DRAWINGS

[0057] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are intended to depict only preferred embodiments of the application, and therefore should not be considered to narrow the scope of the present application. Rather, the entire scope of the present application is to be read and understood by reading the description below along with the accompanying drawings. In the drawings:

[0058] Figure 1 Structure schematic diagram of a vehicle for some embodiments of the present application;

[0059] Figure 2 An exploded structural schematic view of a battery according to some embodiments of the present application;

[0060] Figure 3 An exploded structural schematic view of a battery cell according to some embodiments of the present application;

[0061] Figure 4 A structural schematic view of an electrode assembly according to some embodiments of the present application;

[0062] Figure 5 A sectional structural schematic view of an electrode tab according to some embodiments of the present application;

[0063] Figure 6 A TEM image of a solid particulate silicon-based material according to Embodiment 1 of the present application;

[0064] Figure 7 A XRD image of a solid particulate silicon-based material according to Embodiment 1 of the present application, in which the abscissa is twice the incident angle of x-rays and the ordinate is the diffraction intensity.

[0065] Reference signs in the detailed description of the embodiments are as follows:

[0066] 10 - electrode tab; 1 - current collector; 2 - active material layer;

[0067] 20 - electrode assembly; 101 - negative electrode tab; 102 - positive electrode tab; 201 - negative electrode tab; 202 - positive electrode tab; 203 - separator;

[0068] 30 - battery cell; 301 - shell; 302 - end cap; 303 - negative electrode adapter tab; 304 - positive electrode adapter tab; 305 - insulating member;

[0069] 40 - battery; 401 - box body; 4011 - box body; 4012 - box cover;

[0070] 50 - electric device; 501 - controller; 502 - motor. DETAILED DESCRIPTION

[0071] The embodiments of the technical solutions of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, and cannot limit the protection scope of the present application.

[0072] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of this application; the use of the terms "including," "comprising," or "having" and variations thereof herein is intended to be broad and encompass the terms "consisting of" and "consisting essentially of" and variations thereof. Unless otherwise required by context, singular terms shall include pluralities and vice versa. Unless otherwise required by context, the use herein of the singular is also to be construed as a reference to the plural and vice versa.

[0073] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0074] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification is not necessarily all referring to the same embodiment, or to a particular embodiment, or to a particular set of embodiments. It will be explicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0075] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " herein generally represents an "or" relationship between the front and rear associated objects.

[0076] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two), and similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0077] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as limiting the embodiments of the present application, which do not indicate or imply that the indicated devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application.

[0078] In the description of the embodiments of the present application, unless otherwise explicitly specified and limited, the technical terms "mounting", "connection", "connecting", "fixing" and the like should be understood in a broad sense, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through an intermediate medium, can be internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0079] Lithium ion batteries are widely used due to their high energy density and long cycle life. The performance of the negative electrode material is one of the key factors affecting the overall performance of the lithium ion battery. Currently, graphite is the most commonly used negative electrode material for lithium ion batteries. However, the theoretical specific capacity of graphite is only 372 mAh / g, which cannot meet the requirements of high energy density for various consumer electronic devices, especially energy storage devices and electric vehicles. Silicon-based materials have attracted attention due to their high theoretical specific capacity and abundant reserves. However, silicon-based materials are prone to volume expansion during the cycle process, which leads to electrode pulverization and even peeling off from the current collector, resulting in rapid capacity decay of the battery.

[0080] Therefore, the inventors designed a negative electrode material containing a silicon-based material with a high theoretical specific capacity, thereby improving the theoretical specific capacity of the negative electrode material. The silicon-based material is designed to include solid particle silicon-based material and micro-powder silicon-based material. The solid particle silicon-based material has a ring structure, i.e., it has a shape similar to a "donut". The micro-powder silicon-based material is mixed with the solid particle silicon-based material and fills the hollow ring of the solid particle silicon-based material and / or the gaps between the solid particle silicon-based materials. Since the granular silicon-based material has a through hole, when the silicon-based material expands in volume during lithium intercalation, the hole and / or gap can provide a buffer space to alleviate the volume expansion effect of the silicon-based material, inhibit the silicon-based material from peeling off from the current collector, and improve the cycle stability of the battery.

[0081] Some embodiments of the present application disclose a battery that can be used in an electric device such as a vehicle, a ship or an aircraft, but is not limited thereto. The power supply system of the electric device can be composed of the battery disclosed in the present application.

[0082] Some embodiments of the present application provide a power consuming device using a battery as a power source. The power consuming device can be, but is not limited to, a vehicle, a mobile phone, a portable device, a notebook computer, a ship, a spacecraft, an electric toy, an electric tool, and the like. The vehicle can be, but is not limited to, a fuel vehicle, a gas vehicle, or a new energy vehicle. The new energy vehicle can be, but is not limited to, a pure electric vehicle, a hybrid electric vehicle, or a range extended electric vehicle. The spacecraft includes an airplane, a rocket, a space shuttle, a spacecraft, and the like. The electric toy includes a fixed or mobile electric toy, such as a game console, an electric vehicle toy, an electric ship toy, an electric airplane toy, and the like. The electric tool includes a metal cutting electric tool, a grinding electric tool, an assembling electric tool, and a railway electric tool, such as an electric drill, an electric grinder, an electric wrench, an electric screwdriver, an electric hammer, an impact electric drill, a concrete vibrator, an electric planer, and the like.

[0083] The following embodiments are described by taking a vehicle 50 as an example for convenience of description.

[0084] Please refer to Figure 1 , Figure 1 A structural schematic diagram of the vehicle 50 is provided for some embodiments of the present application. The vehicle 50 is internally provided with a battery 40, which can be arranged at the bottom, the head, or the tail of the vehicle 50. The battery 40 can be used for power supply of the vehicle 50, for example, the battery 40 can be used as an operating power source of the vehicle 50. The vehicle 50 can further include a controller 501 and a motor 502. The controller 501 is used to control the battery 40 to supply power to the motor 502, for example, to meet the power demand of the vehicle 50 during starting, navigation, and driving.

[0085] In some embodiments of the present application, the battery 40 can not only be used as an operating power source of the vehicle 50, but also be used as a driving power source of the vehicle 50, to replace or partially replace fuel or natural gas to provide driving power for the vehicle 50.

[0086] In some embodiments of the present application, the battery 40 is a secondary battery. The secondary battery has various forms, including but not limited to a battery monomer, a battery module, a battery pack, and the like. Here, the secondary battery refers to a battery that can be activated by charging after discharging.

[0087] Please refer to Figure 2 , Figure 2 An exploded view of the battery 40 is provided for some embodiments of the present application. The battery 40 includes a box body 401 and a battery monomer 30, and the battery monomer 30 is accommodated in the box body 401. The box body 401 is used to provide an accommodation space for the battery monomer 30, and the box body 401 can adopt various structures.

[0088] In some embodiments, the box 401 can include a box body 4011 and a box cover 4012, which are coupled to each other and together define a containing space for containing the battery cell 30. Optionally, the box body 4011 can be a hollow structure with one end open, and the box cover 4012 can be a plate-shaped structure, which is coupled to the open end of the box body 4011.

[0089] In the battery 40, the battery cell 30 can be multiple, and the multiple battery cells 30 can be connected in series, in parallel, or in a mixed connection. The mixed connection means that the multiple battery cells 30 are connected in series and in parallel. The multiple battery cells 30 can be directly connected in series, in parallel, or in a mixed connection, and then the multiple battery cells 30 are contained in the box 401; of course, the battery 40 can also be that the multiple battery cells 30 are first connected in series, in parallel, or in a mixed connection to form a battery module, and then the multiple battery modules are connected in series, in parallel, or in a mixed connection to form a whole, and are contained in the box 401. The battery 40 can also include other structures, such as a busbar component (not shown in the figure), for realizing the electrical connection between the multiple battery cells 30.

[0090] Among them, the battery cell 30 can be a secondary battery or a primary battery; it can also be a lithium-sulfur battery, a sodium-ion battery, or a magnesium-ion battery, but is not limited thereto. The battery cell 30 can be in the shape of a cylinder, a flat body, a cuboid, or other shapes.

[0091] Please refer to Figure 3 , Figure 3 for the exploded view of the battery cell 30 in some embodiments of the present application. The battery cell 30 refers to the smallest unit that constitutes a battery. As Figure 3 , the battery cell 30 includes a shell 301, an end cover 302, an electrode assembly 20, and other functional components.

[0092] The shell 301 is a hollow structure with one end open, and the shell 301 is used to cooperate with the end cover 302 to form an internal environment for containing the electrode assembly 20, the electrolyte, and other functional components. The shell 301 can be in various shapes and sizes, such as a cuboid, a cylinder, a hexagonal prism, etc. Specifically, the shape of the shell 301 can be determined according to the specific shape and size of the electrode assembly 20. The material of the shell 301 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not limited herein.

[0093] The end cover 302 refers to a component that covers the opening of the housing 301 to isolate the internal environment of the battery cell 30 from the external environment. Optionally, the shape of the end cover 302 can be adapted to the shape of the housing 301 to fit the housing 301. Optionally, the end cover 302 can be made of a material with certain hardness and strength, such as aluminum alloy, so that the end cover 302 is less likely to deform when subjected to extrusion collision, allowing the battery cell 30 to have higher structural strength and improved safety performance. The material of the end cover 302 can be, but is not limited to, copper, iron, aluminum, stainless steel, aluminum alloy, plastic, etc., which is not limited herein.

[0094] The housing 301 can contain one or more electrode assemblies 20.

[0095] In some embodiments, the battery cell 30 further includes functional components such as a negative tab 303 and a positive tab 304, where the negative tab 303 is used to electrically connect with the negative tab on the electrode assembly 20, and the positive tab 304 is used to electrically connect with the positive tab on the electrode assembly 20 for outputting or inputting the electrical energy of the battery cell 30. It can be understood that the negative tab 303 is made of conductive material, and the material of the negative tab 303 can be, but is not limited to, copper, iron, aluminum, etc. The positive tab 304 is made of conductive material, and the material of the positive tab 304 can be, but is not limited to, copper, iron, aluminum, etc.

[0096] In some embodiments, the battery cell 30 further includes an insulating member 305 located inside the housing 301 for isolating the housing 301 from the electrode assembly 20 to reduce the risk of short circuit. For example, the insulating member 305 can be plastic, rubber, etc.

[0097] Please refer to Figure 4 , Figure 4 is a structural schematic diagram of the electrode assembly 20 in some embodiments of the present application. The electrode assembly 20 is a component in the battery cell 30 where electrochemical reactions occur. The electrode assembly 20 is mainly formed by winding or stacking the electrode sheet structure integrated by the negative electrode sheet 101 and the positive electrode sheet 102, and a separator 203 is usually arranged between adjacent negative electrode sheets 101 and positive electrode sheets 102.

[0098] The negative electrode sheet 101 includes a negative current collector and a negative material layer coated on the surface of the negative current collector. Taking a lithium ion battery as an example, the material of the negative current collector can be copper, and the negative material layer includes a negative material, which can be a silicon-based material, etc.

[0099] The positive electrode tab 102 includes a positive current collector and a positive material layer coated on the surface of the positive current collector. Taking a lithium ion battery as an example, the material of the positive current collector can be aluminum, and the positive material layer includes a positive material, which can be lithium cobalt oxide, lithium iron phosphate, ternary lithium, or lithium manganate, etc.

[0100] The separator 203 is a porous plastic film that allows lithium ions in the electrolyte to pass freely, but separates the negative electrode tab 101 and the positive electrode tab 102, so that the electrons inside the battery cannot pass freely. The material of the separator 203 can be PP (polypropylene) or PE (polyethylene), etc.

[0101] The negative current collector and the positive current collector also have parts that are not coated with the active material layer, and these parts without the active material layer are provided with the connecting tabs. Specifically, the negative current collector is connected with the negative tab 201, and the positive current collector is connected with the positive tab 202. During the charging and discharging process of the battery, the positive material layer and the negative material layer react with the electrolyte, the tab 201 is connected with the negative adapter tab 303 and the positive tab 202 is connected with the positive adapter tab 304 to form a current loop. Of course, in some embodiments, the parts of the negative current collector and the positive current collector that are not coated with the active material layer each constitute a tab.

[0102] Please refer to Figure 5 , Figure 5 for the structure of the electrode tab 10 in some embodiments of the present application. The electrode tab 10 includes a current collector 1 and an active material layer 2, and the active material layer 2 is arranged on at least one side of the current collector 1.

[0103] The current collector 1 refers to a component for converging current. The current collector 1 can be a negative current collector or a positive current collector according to different applications. When the current collector 1 is a negative current collector, the active material layer 2 coated on the negative current collector is a negative material layer, and the resulting electrode tab 10 is a negative electrode tab; when the current collector 1 is a positive current collector, the active material layer 2 coated on the positive current collector is a positive material layer, and the resulting electrode tab 10 is a positive electrode tab. Taking a lithium ion battery as an example, the negative current collector can be a copper foil, and the positive current collector can be an aluminum foil. In addition, the current collector 1 can have various shapes, such as a strip shape or a square shape, which are not limited herein.

[0104] The active material layer 2 includes an active material, a conductive agent, and a binder. The active material refers to a material that participates in an electrochemical oxidation / reduction reaction. Optionally, the active material is a powder. When the active material layer 2 is a negative electrode material layer, the active material is a negative electrode material. When the active material layer 2 is a positive electrode material layer, the active material is a positive electrode material. Taking a lithium ion battery as an example, the negative electrode material can be silicon and / or a silicon oxide; the positive electrode material can be, but is not limited to, lithium cobaltate, lithium manganate, lithium iron phosphate, lithium iron manganese phosphate, lithium nickel cobaltate, lithium nickel manganate, lithium nickel cobalt manganate, lithium-rich manganese-based material, etc. The conductive agent refers to a material that collects micro-currents between the active materials, between the active material and the current collector 1. The conductive agent can be, but is not limited to, conductive graphite, carbon nanotubes, acetylene black, etc. The binder is a material that binds the active material together to enhance the electronic contact between the active material and the conductive agent and between the active material and the current collector 1. The binder can be, but is not limited to, styrene-butadiene rubber (SBR), acrylonitrile, acrylate, polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), etc.

[0105] The current collector 1 has a first surface and a second surface opposite along the thickness direction of the current collector 1. At least one side of the current collector 1 includes the first surface and / or the second surface of the current collector 1. Understandably, the active material layer 2 can be disposed on the first surface, on the second surface, or on both the first surface and the second surface. In some embodiments, the current collector 1 can also be a porous mesh structure, which is that the active material layer 2 can also be located in the mesh holes of the current collector 1.

[0106] In some embodiments of the present application, the negative electrode material includes a silicon-based material, which includes a solid particle silicon-based material with a ring structure and a micro-powder silicon-based material for filling the voids in the hollow ring of the solid particle silicon-based material and / or between the solid particle silicon-based materials.

[0107] Here, the silicon-based material refers to a negative electrode material containing a silicon element. The silicon-based material includes, but is not limited to, elemental silicon or silicon suboxide.

[0108] The solid particle silicon-based material with a ring structure refers to a solid particle silicon-based material that is generally ring-shaped, i.e., a hollow is formed through the solid particle silicon-based material, so that the solid particle silicon-based material presents a shape similar to a "doughnut", and through the hollow, the other side surface of the solid particle silicon-based material can be directly reached from one side surface of the solid particle silicon-based material. Here, the solid particle silicon-based material can be a spherical particle, a round cake-shaped particle, or a special-shaped particle.

[0109] The micro-powder silicon-based material refers to a micro-powder structure silicon-based material, specifically a silicon-based material with a median particle size D50 less than 1 μm. Optionally, the median particle size of the micro-powder silicon-based material is set to be less than the outer diameter of the solid particle silicon-based material, and the micro-powder silicon-based material with small particles can be filled between the solid particle silicon-based materials with larger median particle size, indirectly realizing the contact between the solid particle silicon-based materials and reducing the short circuit phenomenon in the electrode. Optionally, the median particle size of the micro-powder silicon-based material is set to be less than the inner diameter of the solid particle silicon-based material, and the micro-powder silicon-based material can be filled in the hollow ring of the solid particle silicon-based material. For example, the inner diameter of the solid particle silicon-based material is 2 times, 4 times, 6 times, 8 times or 10 times of the median particle size of the micro-powder silicon-based material. Optionally, the inner diameter of the solid particle silicon-based material is 1 μm-3 μm, and the median particle size of the micro-powder silicon-based material is 0.1 μm-0.5 μm. Generally, since the solid particle silicon-based material is a geometric body with a certain volume size, a gap will be formed between the solid particle silicon-based materials, and the gap will increase as the size of the solid particle silicon-based material increases. Since the median particle size of the micro-powder silicon-based material is set to be less than the inner diameter of the solid particle silicon-based material, the micro-powder silicon-based material will also be filled in the gap between the solid particle silicon-based materials.

[0110] By designing the negative electrode material to include a silicon-based material with a higher theoretical specific capacity, while the silicon-based material includes a solid particle silicon-based material and a micro-powder silicon-based material, wherein the solid particle silicon-based material has a ring structure, i.e., the solid particle silicon-based material has a shape similar to a "doughnut", and the solid particle silicon-based material has a hollow formed thereon, and the micro-powder silicon-based material is filled in the hollow of the solid particle silicon-based material and / or the gap between the solid particle silicon-based materials. By using the silicon-based material, the capacity performance of the negative electrode material can be improved, and by using the hollows through the solid particle silicon-based material and / or the gaps between the solid particle silicon-based materials, when the silicon-based material expands in volume during lithium intercalation, the hollows and / or gaps can provide a buffer space, so that the stress generated by the expansion of the silicon-based material is more easily dissipated, the volume expansion effect of the silicon-based material is alleviated, the outward expansion of the negative electrode material is reduced, the peeling of the silicon-based material from the current collector is inhibited, and the cycle stability of the battery is improved.

[0111] At the same time, the hollows on the solid particle silicon-based material can also serve as channels for the electrolyte to infiltrate the negative electrode material, and lithium ions can diffuse and migrate from different outer surfaces of the solid particle silicon-based material to the interior of the solid particle silicon-based material, with a shorter migration path, thereby improving the rate performance of the battery. In addition, the specific surface area of the micro-powder silicon-based material is larger, with more reaction active sites, accelerating the interface reaction and improving the kinetic performance of the battery.

[0112] According to some embodiments of the present application, the chemical formula of the silicon-based material is SiO x , wherein 0≤x<2.

[0113] The chemical formula of the silicon-based material is SiO x , and 0≤x<2. Understandably, the silicon-based material herein can be elemental silicon or can be silicon monoxide, i.e., an incomplete oxide of silicon. Herein, x represents the oxygen content in the silicon-based material, and x can be 0 or any value between 0 and 2, such as 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or 1.99, etc. When x=0, the silicon-based material contains elemental silicon. When 0

[0114] It should be noted that the silicon-based material includes solid particle silicon-based material and micro-powder silicon-based material, and the compositions of the solid particle silicon-based material and the micro-powder silicon-based material can be the same or different. For example, in some embodiments, the solid particle silicon-based material contains elemental silicon, and the micro-powder silicon-based material contains silicon monoxide; in other embodiments, the solid particle silicon-based material and the micro-powder silicon-based material both contain silicon monoxide.

[0115] By setting the silicon-based material to be elemental silicon and / or silicon monoxide with a higher theoretical specific capacity, the theoretical specific capacity of the negative electrode material is improved, and the energy density of the battery is improved.

[0116] According to some embodiments of the present application, 0.9≤x≤1.1.

[0117] The main reason for the large volume effect of the silicon-based material is that the silicon-based material forms Li x Si during lithiation. Generally, SiO x generates elemental silicon, lithium oxide, and lithium silicate (Li x SiO y ) during the first lithiation process. The elemental silicon generated by the reaction is the real lithium storage function. Therefore, the volume effect of SiO x is closely related to the oxygen content, i.e., the value of x. The value of x decreases, the content of elemental silicon increases, the effective capacity increases, but the volume effect also increases, and the cycle stability of the negative electrode material decreases. The value of x increases, the content of elemental silicon decreases, the effective capacity decreases, and the conductivity decreases, but the volume effect is slowed down, and the cycle stability of the negative electrode material is improved.

[0118] Alternatively, x is 0.9, 0.95, 1.0, 1.05, or 1.1.

[0119] By setting x as 0.9-1.1, i.e. the silicon-based material is silicon monoxide, and the content of oxygen in the silicon monoxide is close to the content of silicon, the silicon monoxide in the ratio range not only has a much higher specific capacity than graphite, but also does not have a violent volume expansion during the charging process like elemental silicon, and can ensure the generation of sufficient elemental silicon during the lithiation process, ensuring the electrical conductivity and effective capacity.

[0120] According to some embodiments of the present application, the outer diameter of the solid particulate silicon-based material is 6-9 μm, and the inner diameter is 1-3 μm.

[0121] Here, the outer diameter refers to the maximum distance value of the outer surface of the solid particulate silicon-based material; and the inner diameter refers to the minimum distance value of the inner surface of the hollow ring of the solid particulate silicon-based material. Optionally, the outer diameter is 6 μm, 6.5 μm, 7 μm, 7.5 μm, 8 μm, 8.5 μm or 9 μm. Optionally, the inner diameter is 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm. The outer diameter and the inner diameter of the solid particulate silicon-based material can be measured by a method known in the art, for example, the average diameter can be obtained by using NanoMeasurer software to statistically analyze and calculate the results according to SEM and TEM test results.

[0122] A too large outer diameter will increase the volume of the solid particulate silicon-based material, and a too small inner diameter will increase the wall thickness of the ring-shaped solid particulate silicon-based material, both of which are not conducive to the diffusion and migration of lithium ions in the solid particulate silicon-based material; by setting the outer diameter of the solid particulate silicon-based material as 6-9 μm and the inner diameter as 1-3 μm, the rate performance of the negative electrode material prepared in this range is better.

[0123] According to some embodiments of the present application, the surface area of the solid particulate silicon-based material is 3.14 μm 2 -12.56 μm 2 .

[0124] The surface area here refers to the surface area of a single solid particulate silicon-based material, including the outer surface area and the inner surface area of the hollow ring. Optionally, the surface area of the solid particulate silicon-based material is 3.14 μm 2 , 4 μm 2 , 5 μm 2 , 6 μm 2 , 7 μm 2 , 8 μm 2 , 9 μm 2 , 10 μm 2 , 11 μm 2 , 12 μm 2 or 12.56 μm 2 .

[0125] As an example, the solid particulate silicon-based material can be approximated as a sphere, the average diameter of the solid particulate silicon-based material can be measured by TEM, and the surface area of the solid particulate silicon-based material can be calculated using the surface area formula of a sphere.

[0126] The increase of the surface area of the solid particulate silicon-based material can increase the number of reaction active sites of the negative electrode material, accelerate the interface reaction, and improve the kinetic performance of the battery. However, the increase of the surface area of the solid particulate silicon-based material can also increase the area of the SEI film, thereby increasing the consumption of lithium ions. The surface area of the solid particulate silicon-based material is set to 3.14 μm 2 ~ 12.56 μm 2 In this range, the electrochemical performance of the negative electrode material is relatively good.

[0127] According to some embodiments of the present application, the specific surface area of the solid particulate silicon-based material is 2.4 m 2 / g ~ 3.6 m 2 / g.

[0128] The specific surface area refers to the total area per unit mass of the material. The specific surface area of the solid particulate silicon-based material can be measured by nitrogen adsorption / desorption measurement. Alternatively, the specific surface area of the solid particulate silicon-based material is 2.4 m 2 / g, 2.5 m 2 / g, 2.6 m 2 / g, 2.7 m 2 / g, 2.8 m 2 / g, 2.9 m 2 / g, 3.0 m 2 / g, 3.1 m 2 / g, 3.2 m 2 / g, 3.3 m 2 / g, 3.4 m 2 / g, 3.5 m 2 / g, or 3.6 m 2 / g.

[0129] The increase of the specific surface area of the solid particulate silicon-based material can increase the number of reaction active sites of the negative electrode material, accelerate the interface reaction, and improve the kinetic performance of the battery. However, the increase of the specific surface area of the solid particulate silicon-based material can also increase the area of the SEI film, thereby increasing the consumption of lithium ions. The specific surface area of the solid particulate silicon-based material is in the above range, and the electrochemical performance of the negative electrode material is relatively good.

[0130] According to some embodiments of the present application, the specific surface area of the negative electrode material is 3 m 2 / g ~ 5 m 2 / g.

[0131] The specific surface area of the negative electrode material can also be measured by nitrogen adsorption / desorption measurement method. Optionally, the specific surface area of the negative electrode material is 3.0 m 2 / g, 3.2 m 2 / g, 3.4 m 2 / g, 3.6 m 2 / g, 3.8 m 2 / g, 4.0 m 2 / g, 4.2 m 2 / g, 4.4 m 2 / g, 4.6 m 2 / g, 4.8 m 2 / g, or 5.0 m 2 / g.

[0132] Compared with the solid particle silicon-based material, the specific surface area of the negative electrode material loaded with the micro-powder silicon-based material increases because the micro-powder silicon-based material has a higher specific surface area. Generally, the increase of the specific surface area of the negative electrode material can increase the number of active sites of the negative electrode material, accelerate the interface reaction, and improve the kinetic performance of the battery. However, the increase of the specific surface area will also increase the area of the SEI film, thereby increasing the consumption of lithium ions. When the specific surface area of the negative electrode material is within the above range, the electrochemical performance of the negative electrode material is relatively optimal.

[0133] According to some embodiments of the present application, the SiO x is an amorphous material, and the surface of the solid particle silicon-based material is wrapped with a carbon layer.

[0134] The amorphous material refers to a material in which the arrangement of atoms or molecules inside the material is chaotic and has no periodicity. The surface of the solid particle silicon-based material includes the outer surface and the inner surface of the hollow ring.

[0135] Since the SiO x is an amorphous material, the disorder of atomic distribution leads to low electronic conductivity. By wrapping the surface of the solid particle silicon-based material with a carbon layer, the electrical conductivity of the solid particle silicon-based material is improved, thereby improving the rate performance of the negative electrode material.

[0136] According to some embodiments of the present application, the solid particle silicon-based material is a sphere or a sphere-like body.

[0137] The sphere refers to a rotational body formed by rotating a semicircle around a diameter along a straight line. The sphere-like body refers to a geometric body with a shape close to the sphere.

[0138] By setting the solid particle silicon-based material as a sphere or a sphere-like body, the solid particle silicon-based materials are beneficial to form voids, which can provide a buffer space when the solid particle silicon-based material expands, so that the stress generated by the expansion of the solid particle silicon-based material is more easily dissipated.

[0139] According to some embodiments of the present application, the median median particle size of the fine silicon-based material is 0.1-0.5 μm.

[0140] The grain size, also known as particle size or diameter, refers to the size of the fine powder particles in the fine silicon-based material, specifically the median particle size D50. Optionally, the median particle size of the fine silicon-based material is 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm or 0.5 μm.

[0141] Generally, the smaller the median particle size of the fine silicon-based material, the more the fine silicon-based material can be filled into the hollow rings of the solid particulate silicon-based material and the gaps between the solid particulate silicon-based materials, thereby improving the capacity of the negative electrode material. However, the smaller the median particle size of the fine silicon-based material, the lower the porosity of the negative electrode material layer during the formation of the negative electrode material layer, which leads to an increase in the expansion rate of the negative electrode material, and the manufacturing cost of the fine silicon-based material also increases. Generally, the larger the median particle size of the fine silicon-based material, the less the fine silicon-based material can be filled into the hollow rings of the solid particulate silicon-based material and the gaps between the solid particulate silicon-based materials, and the larger the median particle size of the fine silicon-based material, the more difficult it is for lithium ions to diffuse in the fine silicon-based material, which reduces the rate performance of the negative electrode material. Therefore, by reasonably setting the median particle size of the fine silicon-based material, the capacity, expansion and rate performance of the negative electrode material can be simultaneously considered.

[0142] According to some embodiments of the present application, the mass ratio of the solid particulate silicon-based material to the fine silicon-based material is 4:(1-2).

[0143] Since the fine silicon-based material also expands in volume when lithium is inserted, the larger the amount of the fine silicon-based material filled in the solid particulate silicon-based material, the larger the volume of the fine silicon-based material that expands when lithium is inserted. If the volume of the fine silicon-based material that expands exceeds a limit, it can also cause the electrode to expand and even cause the negative electrode material to fall off.

[0144] Optionally, the mass ratio of the solid particulate silicon-based material to the fine silicon-based material is 4:1, 4:1.2, 4:1.4, 4:1.6, 4:1.8 or 4:2.

[0145] Optionally, the outer diameter of the solid particulate silicon-based material is 6-9 μm, and the inner diameter is 1-3 μm.

[0146] By setting the mass ratio of the solid particulate silicon-based material to the fine silicon-based material to be 4:(1-2), within this range, the volume of the solid particulate silicon-based material and the fine silicon-based material that expands when lithium is inserted can be just absorbed by the hollows of the solid particulate silicon-based material and the gaps between the solid particulate silicon-based materials, preventing the negative electrode material from expanding excessively outward.

[0147] According to some embodiments of the present application, the negative material further comprises graphite, and a median particle size of the graphite is greater than an outer diameter of the solid particulate silicon-based material.

[0148] Graphite is a material that is resistant to high temperature and corrosion, and has good electrical conductivity, thermal conductivity and stable chemical properties. Here, the graphite can be, but is not limited to, natural graphite, artificial graphite and composite graphite. The graphite can be, but is not limited to, flaky, massive and the like.

[0149] The median particle size of the graphite is greater than the median particle size of the solid particulate silicon-based material. When the negative material further comprises a micro-powder silicon-based material, because the median particle size of the solid particulate silicon-based material is greater than the median particle size of the micro-powder silicon-based material, the median particle size of the micro-powder silicon-based material is also less than the median particle size of the graphite. The micro-powder silicon-based material is used to fill between the graphite and the solid particulate silicon-based material with a ring structure. Because the expansion of the graphite is small, the graphite is used to buffer the expansion stress of the silicon-based material. When the negative material forms a negative material layer, the local stress of the negative material layer is prevented from being too large to cause fragmentation. At the same time, the small particles of the micro-powder silicon-based material are used to fill between the large particles of the graphite and the solid particulate silicon-based material, to improve the contact between the large and small particles and to improve the electrical conductivity effect. Otherwise, a large amount of conductive agent needs to be added to link the solid particulate silicon-based material, which reduces the specific capacity of the negative material. In addition, because the median particle sizes of the graphite, the solid particulate silicon-based material and the micro-powder silicon-based material are distributed in a stepped growth manner, the graphite with a large median particle size is matched with the solid particulate silicon-based material with a medium median particle size and the micro-powder silicon-based material with a small median particle size, which is conducive to avoiding agglomeration between different materials and reducing the rate performance of the negative material. Here, large, medium and small refer to the comparison among the three.

[0150] Because the volume of the graphite expands less during charging and discharging, and the median particle size of the graphite is greater than the outer diameter of the solid particulate silicon-based material, by adding the graphite in the solid particulate silicon-based material with a ring structure, a gap is constructed between the graphite and the solid particulate silicon-based material to relieve the expansion of the silicon-based material and slow down the outward expansion of the negative material. At the same time, because the main component of the solid particulate silicon-based material with a ring structure is elemental silicon and / or silicon oxide, the electrical conductivity is poor. By adding the graphite in the negative material, the graphite is used to construct an electrical conductivity network in the negative material to ensure better contact between the solid particulate silicon-based material and the current collector and between the solid particulate silicon-based materials.

[0151] According to some embodiments of the present application, the median particle size of the graphite is 10 μm to 20 μm.

[0152] Optionally, the median particle size of the graphite is 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm.

[0153] As the negative active material, if the median particle size of the graphite is too large, the rate capability of the negative active material is reduced, and if the median particle size of the graphite is too small, the porosity of the negative active material is reduced, and the expansion stress of the silicon-based material cannot be well buffered. By setting the median particle size of the graphite to be 10 μm to 20 μm, the negative active material prepared in this range has better expansion resistance and rate capability.

[0154] According to some embodiments of the present application, the theoretical mass specific capacity of the negative active material is 1100 mAh / g to 1400 mAh / g.

[0155] The theoretical mass specific capacity of the negative active material refers to the weighted average of the theoretical mass specific capacities of the components in the negative active material. Optionally, the negative active material includes a solid particulate silicon-based material in a ring shape, a micro-powder silicon-based material, and graphite. For example, the negative active material contains 0.3 g of a solid particulate silicon-based material, 0.1 g of a micro-powder silicon-based material, and 0.6 g of graphite, wherein the solid particulate silicon-based material is silicon monoxide, the micro-powder silicon-based material is elemental silicon, the theoretical mass specific capacity of the silicon monoxide is 2100 mAh / g, the theoretical mass specific capacity of the elemental silicon is 4200 mAh / g, and the theoretical mass specific capacity of the graphite is 372 mAh / g. The theoretical mass specific capacity of the negative active material is (0.3 g*2100 mAh / g+0.1 g*4200 mAh / g+0.6 g*372 mAh / g) / (0.3 g+0.1 g+0.6 g)=1273.2 mAh / g.

[0156] Generally, the theoretical mass specific capacity of the negative active material can be changed by changing the components in the negative active material, and the theoretical mass specific capacity of the negative active material can also be changed by changing the proportions of the components in the negative active material. The theoretical mass specific capacity of the negative active material is 1100 mAh / g to 1400 mAh / g, and it is known that the negative active material cannot be entirely elemental silicon, because the theoretical mass specific capacity of the elemental silicon is much higher than 1400 mAh / g, and the volume expansion rate of the elemental silicon is also higher during the charging and discharging process. Therefore, the negative active material must contain a substance whose theoretical mass specific capacity is less than that of the elemental silicon, including but not limited to silicon monoxide or carbon material, etc. The volume expansion rate of these substances during the charging and discharging process is also often less than that of the elemental silicon.

[0157] Optionally, the theoretical mass specific capacity of the negative active material is 1100 mAh / g, 1150 mAh / g, 1200 mAh / g, 1250 mAh / g, 1300 mAh / g, 1350 mAh / g, or 1400 mAh / g.

[0158] By setting the theoretical mass specific capacity of the negative electrode material to 1100mAh / g-1400mAh / g, compared with the traditional graphite negative electrode material, the theoretical mass specific capacity of the negative electrode material is improved, and compared with the single-element negative electrode material, the volume expansion rate of the negative electrode material is well inhibited.

[0159] Some embodiments of the present application also provide a negative electrode sheet, which comprises a negative electrode current collector and a negative electrode material layer arranged on at least one side of the negative electrode current collector, and the negative electrode material layer comprises the negative electrode material described above.

[0160] Optionally, the negative electrode material layer is arranged on one side of the negative electrode current collector. Optionally, the negative electrode material layer is arranged on the opposite surfaces of the negative electrode current collector along the thickness direction.

[0161] By using the solid particle silicon-based material with a ring structure in the negative electrode material layer, and the solid particle silicon-based material containing a silicon-based material with a higher theoretical specific capacity, the theoretical specific capacity of the negative electrode material can be improved by using the silicon-based material, and at the same time, by using the hollows penetrating through the solid particle silicon-based material, when the silicon-based material expands in volume due to lithium intercalation, the hollows can provide a buffer space, so that the stress generated by the expansion of the silicon-based material is more easily dissipated, the volume expansion effect of the silicon-based material is alleviated, the peeling of the silicon-based material from the current collector is inhibited, and the cycle stability of the battery is improved.

[0162] According to some embodiments of the present application, along the thickness direction of the negative electrode material layer, the porosity of the negative electrode material layer gradually increases from the inside to the surface.

[0163] The negative electrode material layer is arranged on the current collector, and along the thickness direction of the negative electrode material layer, the inside to the surface of the negative electrode material layer refers to the direction from the side close to the current collector to the side away from the current collector. The porosity of the negative electrode material layer gradually increases from the inside to the surface refers to the porosity of the area closer to the current collector is smaller, and the porosity of the area farther away from the current collector is larger, that is, the porosity of the area closer to the outer surface of the negative electrode material layer is larger.

[0164] Generally, in the process of lithiation of the negative material layer, the electrolyte first infiltrates the negative material, and then lithium ions in the electrolyte gradually migrate and diffuse into the negative material layer and react with the active material of the negative material layer to form lithium compounds. The closer to the outer surface of the negative material layer, the higher the concentration of lithium ions, and the more lithium compounds are generated. Therefore, the expansion of the negative material is more serious. By setting the negative material layer to have gradually increasing porosity from the inside to the surface, the overall stress distribution of the negative material layer during charging can be uniform, and the local stress of the negative material layer can be inhibited from being too large to cause the negative material layer to fall off. At the same time, the pores in the negative material layer can also serve as channels for lithium ion diffusion. The negative material layer has gradually increasing porosity from the inside to the surface, thereby forming a gradient mass transfer on the negative material layer, which is beneficial to the rapid diffusion of lithium ions into the interior of the negative material layer and improves the rate performance of the battery.

[0165] According to some embodiments of the present application, the above-mentioned negative material is located in the surface layer of the negative material layer.

[0166] Here, the surface layer of the negative material layer refers to the portion of the material layer on the negative material layer that is away from the current collector. The thickness of the surface layer is less than the total thickness of the negative material layer.

[0167] Optionally, the negative material layer includes a first sub-layer disposed on the surface of the current collector and a second sub-layer disposed on the surface of the first sub-layer, the second sub-layer containing the above-mentioned negative material, and the first sub-layer containing a carbon material, including but not limited to petroleum coke and graphite. In preparation, the first sub-layer is first coated on the surface of the current collector, and then the second sub-layer is coated on the surface of the first sub-layer.

[0168] By arranging the above-mentioned negative material on the surface layer of the negative material layer, the negative material is in contact with the electrolyte. Since the above-mentioned negative material contains solid particle silicon-based material and micro-powder silicon-based material, the hollows on the solid particle silicon-based material can serve as channels for the electrolyte to infiltrate the negative material. At the same time, the micro-powder silicon-based material has more active sites, which can accelerate the interface reaction and improve the rate performance of the negative electrode sheet.

[0169] According to some embodiments of the present application, a preparation method of the negative material is also provided, comprising:

[0170] providing a solid particle silicon-based material and a micro-powder silicon-based material with a ring structure;

[0171] mixing and processing the solid particle silicon-based material and the micro-powder silicon-based material so that the micro-powder silicon-based material is filled in the hollow ring of the solid particle silicon-based material and / or in the gap between the solid particle silicon-based materials.

[0172] The solid particle silicon-based material and the micro-powder silicon-based material can be directly purchased materials or prepared materials.

[0173] Mixing solid particulate silicon-based materials and micronized silicon-based materials refers to blending solid particulate silicon-based materials and micronized silicon-based materials together. Optionally, after blending the solid particulate silicon-based materials and micronized silicon-based materials together, a stirring process is also included to disperse the solid particulate silicon-based materials and micronized silicon-based materials to achieve a uniform state.

[0174] By mixing solid particulate silicon-based materials and micronized silicon-based materials, and using the micronized silicon-based materials to fill the voids in the solid particulate silicon-based materials and / or the gaps between the solid particulate silicon-based materials, these voids and / or gaps can provide a buffer space when the silicon-based materials undergo volume expansion due to lithium intercalation. This makes it easier to dissipate the stress generated by the expansion of the silicon-based materials, alleviate the volume expansion effect of the silicon-based materials, reduce the outward expansion of the negative electrode materials, inhibit the peeling of the silicon-based materials from the current collector, and improve the cycle stability of the battery.

[0175] According to some embodiments of this application, the preparation of a solid particulate silicon-based material with a ring structure is further included before providing the solid particulate silicon-based material with a ring structure, specifically including:

[0176] Provide silicon-based material starting materials;

[0177] The initial silicon-based material is pulverized to obtain pulverized particles;

[0178] The pulverized particles are prepared into a suspension solution, and the suspension solution is spray-dried to obtain a silicon-based material comprising solid particles with a ring structure.

[0179] Silicon-based material starting material refers to the chemical formula SiO x Materials for which 0 ≤ x < 2. It can be understood that the initial material for silicon-based materials can be elemental silicon or silicon suboxide. The initial material for silicon-based materials can be granular or bulk; this is not limited here.

[0180] Optionally, the silicon-based material starting material is silicon suboxide, i.e., 0 < x < 2. Before providing the silicon-based material starting material, the process also includes preparing the silicon-based material starting material, specifically including: preparing silicon suboxide (SiO) from a mixed raw material comprising elemental silicon and silicon dioxide using chemical vapor deposition. x The deposited product, where 0 < x < 2. Optionally, the elemental silicon (Si) is high-purity silicon with a purity of not less than 99.9%. Optionally, the silicon dioxide (SiO2) is high-purity silicon dioxide with a purity of not less than 99.9%. Optionally, the molar ratio of elemental silicon to silicon dioxide is (0.9 to 1.1):1, for example, a molar ratio of 0.9:1, 1:1, or 1.1:1.

[0181] Optionally, the mixed raw material including elemental silicon and silicon dioxide is prepared into a deposition product including silicon monoxide by a chemical vapor deposition method, specifically including: mixing and grinding the elemental silicon and the silicon dioxide to obtain a mixed raw material; under a protective atmosphere, heating the mixed raw material to 900-1100°C at a rate of 3-5°C / min to generate silicon monoxide by a centering reaction; continuing to heat to 1100-1500°C at a rate of 5-10°C / min to vaporize the silicon monoxide; mixing the vaporized silicon monoxide with an inert gas and introducing the mixture into a chemical vapor deposition furnace to obtain the deposition product including silicon monoxide by chemical vapor deposition. Optionally, the initial temperature in the chemical vapor deposition furnace is 600-900°C, and the temperature is lowered to 200-450°C for chemical vapor deposition. Optionally, the pressure is constant at 1-100 MPa during the chemical vapor deposition.

[0182] The pulverization treatment includes at least one of mechanical pulverization and air flow pulverization. Optionally, the mechanical pulverization includes ball milling. Optionally, the pulverized particles obtained by the air flow pulverization have a median particle size of 3-15 μm, such as 3 μm, 5 μm, 7 μm, 9 μm, 11 μm, 13 μm or 15 μm.

[0183] The suspension solution refers to a substance distributed in a liquid without being dissolved but merely dispersed therein. Optionally, the pulverized particles are added to a solvent, such as deionized water, and then stirred to obtain the suspension solution.

[0184] The silicon-based material with a ring structure is prepared by pulverizing the initial material of the silicon-based material, preparing a suspension solution and performing a dry spray treatment, which is simple and easy to operate.

[0185] According to some embodiments of the present application, the spray drying treatment includes atomizing the suspension solution and injecting it into a hot air stream for drying, the temperature of the drying air being 90-110°C, and the solution flow rate being 80-120 L / min.

[0186] The atomization treatment refers to an operation of dispersing a liquid into small droplets by a nozzle or using a high-speed air flow. The atomization of the suspension solution refers to dispersing the suspension solution into small droplets, and the pulverized particles are wrapped in the small droplets.

[0187] The temperature of the drying air is 90-110°C, and optionally, the temperature of the drying air is 90°C, 95°C, 100°C, 105°C or 110°C.

[0188] The solution flow rate is 80 L / min to 120 L / min, and the solution flow rate is 80 L / min, 85 L / min, 90 L / min, 95 L / min, 100 L / min, 105 L / min, 110 L / min, 115 L / min or 120 L / min.

[0189] The suspension solution prepared by crushing the particles is atomized into small droplets and then injected into a hot air stream, and the temperature of the drying air is controlled to be 90°C to 110°C, the solution flow rate is 80 L / min to 120 L / min, and the small droplets are quickly vaporized and dried in the hot air, and the crushed particles wrapped in the small droplets are deformed, thereby preparing a solid particle silicon-based material with a ring structure, i.e., a solid particle silicon-based material with a donut structure. The preparation method is simple, and the yield is considerable.

[0190] According to some embodiments of the present application, the preparation method of the negative electrode material further comprises a pre-lithiation treatment of the solid particle silicon-based material.

[0191] The pre-lithiation treatment refers to a process of providing an external lithium source. Optionally, the reaction of vaporized metallic lithium and SiO x The pre-lithiated negative electrode material can be obtained by reacting the vaporized metallic lithium with SiO

[0192] The first efficiency of the negative electrode material can be improved to 92% by the pre-lithiation treatment.

[0193] According to some embodiments of the present application, the preparation method of the negative electrode material further comprises a step of carbon-coating treatment of the obtained solid particle silicon-based material with a ring structure.

[0194] The carbon-coating treatment refers to a process of coating a carbon layer on the surface of the solid particle silicon-based material. Optionally, the method of carbon-coating treatment includes one of solid-phase coating, liquid-phase coating and gas-phase coating.

[0195] The carbon layer is coated on the surface of the solid particle silicon-based material by the carbon-coating treatment. Compared with silicon material, the carbon material has better electrical conductivity, and the carbon layer coated on the solid particle silicon-based material can effectively improve the electrical conductivity of the negative electrode material and optimize the rate performance of the negative electrode material.

[0196] The following will be described in conjunction with specific embodiments.

[0197] Example 1

[0198] S1: Preparation of a solid particle silicon-based material:

[0199] Mixing and grinding silicon element and silicon dioxide with a molar ratio of 0.95:1 to obtain a mixed raw material; under a protective atmosphere, heating the mixed raw material to 1050°C at a rate of 5°C / min to perform a centering reaction to generate silicon monoxide; continuing to heat to 1300°C at a rate of 8°C / min to vaporize the silicon monoxide; mixing the vaporized silicon monoxide with an inert gas and introducing it into a chemical vapor deposition furnace to obtain a deposition product including silicon monoxide by chemical vapor deposition. The initial temperature in the chemical vapor deposition furnace is 650°C, and the temperature is lowered to 400°C to perform chemical vapor deposition. The pressure is constant at 10 MPa during the chemical vapor deposition process.

[0200] The product obtained by chemical vapor deposition is crushed into particles with a median particle size of 6 μm by airflow crushing.

[0201] The crushed particles are added to a solvent, deionized water, and stirred to prepare a suspension solution; the suspension solution is atomized and injected into a hot air stream for drying, with the temperature of the drying air being 95°C and the solution flow rate being 90 L / min, to obtain solid particulate silicon-based material.

[0202] The product obtained by chemical vapor deposition is crushed into particles with a median particle size of 0.3 μm by airflow crushing.

[0203] S2: Preparation of a negative electrode material: mixing and matching solid particulate silicon-based material (inner diameter 3 μm, outer diameter 7 μm), graphite (median particle size 20 μm), and micro-powder silicon-based material (median particle size 0.3 μm) to obtain a negative electrode material. The solid particulate silicon-based material: graphite: micro-powder silicon-based material = 4:5:1. The theoretical specific capacity of the negative electrode material is 1100 mAh / g.

[0204] S3: Preparation of a battery

[0205] (1) The positive electrode slurry is coated on a 10 μm thick aluminum foil, pressed, and a positive electrode sheet with a thickness of 400 μm is obtained. The positive electrode slurry is NCM98:SP:SWCNT:PVDF = 96:2:0.6:0.2:1.2; the positive electrode slurry viscosity is 7500 mpa·s, and the solid content is 68 wt%. The above NCM98 is a positive electrode material, SP is conductive carbon black, SWCNT is a carbon nanotube, and PVDF is a binder.

[0206] (2) The negative electrode slurry is coated on a 4.5 μm thick copper foil, with a coating thickness of 125 μm, and a negative electrode sheet with a thickness of 110 μm is obtained. The negative electrode slurry is SiO:SP:SWCNT:PAALi = 96.8:1.04:0.06:2.1, where SiO refers to the negative electrode material prepared in the above step S2, SP is conductive carbon black, SWCNT is a carbon nanotube, and PAALi is a binder.

[0207] (3) The negative electrode tab, the positive electrode tab, the separator and the electrolyte were assembled into a soft package battery, and the battery was placed at 45°C for 24h.

[0208] (4) After high-temperature standing, formation and capacity distribution were performed to record the first efficiency and the medium voltage. The specific steps of formation and capacity distribution included: the battery after high-temperature standing was placed for 12h, then constant current charging was performed at a current of 0.02C to 3.5V, then constant current discharging was performed at a current of 0.1C to 4.6V, then constant voltage charging was performed at a voltage of 4.6V to a current of 0.02C, the standing time was 3min, 0.1C constant current discharging was performed to 2.5V, pressure reduction and air extraction were performed, and the battery was sealed, and formation and capacity distribution were completed.

[0209] (5) After formation and capacity distribution, 0.5C cycling was performed.

[0210] Example 2

[0211] The difference from Example 1 is that the solid particulate silicon-based material: graphite: micro-powder silicon-based material = 4:4.5:1.5. The theoretical gram capacity of the negative electrode material is 1174mAh / g.

[0212] Example 3

[0213] The difference from Example 1 is that the solid particulate silicon-based material: graphite: micro-powder silicon-based material = 4:4:2. The theoretical gram capacity of the negative electrode material is 1248mAh / g.

[0214] Comparative Example 1

[0215] The difference from Example 1 is that the negative electrode material comprises a solid particulate silicon-based material and graphite, and the solid particulate silicon-based material: graphite = 5:5. The theoretical gram capacity of the negative electrode material is 1100mAh / g.

[0216] Comparative Example 2

[0217] The difference from Example 1 is that the negative electrode material is graphite, and the theoretical gram capacity of the negative electrode material is 360mAh / g.

[0218] Comparative Example 3

[0219] The difference from Example 1 is that the negative electrode material is micro-powder silicon-based material, and the theoretical gram capacity of the negative electrode material is 1840mAh / g.

[0220] In order to verify the progressiveness of the embodiments of the present application, the samples of the examples and the comparative examples were respectively tested as follows:

[0221] 1. The morphology of the solid particulate silicon-based material prepared in step S1 in Example 1 was observed, as shown in FIG. 1.

[0222] 1. The morphology of the solid particulate silicon-based material prepared in step S1 in Example 1 was observed, as shown in FIG. 1. Figure 6TEM images, it can be seen that the prepared solid particulate silicon-based material is a hollow ring structure, and the solid particulate silicon-based material is generally spherical, approximately in the shape of a "doughnut". Figure 6 TEM images, it can be seen that the prepared solid particulate silicon-based material is a hollow ring structure, and the solid particulate silicon-based material is generally spherical, approximately in the shape of a "doughnut".

[0223] 2, the solid particulate silicon-based material prepared in step S1 in example 1 was subjected to x-ray diffraction test, and the x-ray diffraction (XRD) test results are shown in the following figure. Figure 7 The x-ray diffraction (XRD) test results show that the silicon-based material contained in the prepared solid particulate silicon-based material is amorphous material.

[0224] 3, the battery energy density of the battery prepared in examples 1 to 3 and comparative examples 1 to 3 was tested, and the test results are shown in table 1. From the results in table 1, it can be seen that in examples 1 to 3, with the increase of the proportion of micro-powder silicon-based material in the negative electrode material, the theoretical gram capacity of the negative electrode material also increases, thereby increasing the energy density of the finally prepared battery. Compared with the graphite electrode in the prior art (comparative example 2), the energy density of the battery is significantly increased.

[0225] 4, the expansion rate of the electrode sheet prepared in examples 1 to 33 and comparative examples 1 to 3 was tested, wherein the thickness of the electrode sheet after cold pressing at the initial test was L0, the full charge thickness at the initial test was L1, and P1=(L1-L0) / L0*100% was calculated; the full charge thickness L2 at the storage end point was tested, and P2=(L2-L0) / L0*100% was calculated, and the test results are shown in table 1. From the results in table 1, it can be seen that in examples 1 to 3, with the increase of the proportion of micro-powder silicon-based material in the negative electrode material, the expansion rate of the electrode sheet increases. Compared with example 1, in the case of the same capacity, without adding micro-powder silicon-based material, the expansion rate of the electrode sheet increases. At the same time, compared with the silicon powder electrode in the prior art (comparative example 3), after adding the doughnut structure solid particulate silicon-based material in the negative electrode material, the expansion rate of the electrode sheet is well inhibited.

[0226] Table 1

[0227] Energy density (Wh / Kg) P1(％) P2(％) Example 1 430 40 45 Example 2 440 44 49 Example 3 450 52 60 Comparative Example 1 430 70 75 Comparative Example 2 290 25 30 Comparative Example 3 455 90 95

[0228] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not intended to limit the present application; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some or all of the technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application, and they should be covered in the scope of the claims and the description of the present application. In particular, as long as there is no structural conflict, each technical feature mentioned in each embodiment can be combined in any way. The present application is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A negative electrode material, characterized by, The silicon-based material comprises solid particle silicon-based material with ring structure and micro-powder silicon-based material for filling the interspace in the hollow ring of the solid particle silicon-based material and / or between the solid particle silicon-based materials.

2. The negative electrode material according to claim 1, characterized in that, The chemical formula of the silicon-based material is SiO x wherein 0≤x<2.

3. The negative electrode material according to claim 2, characterized in that, 0.9≤x≤1.1。 4. The negative electrode material of claim 1, wherein, The solid particle silicon-based material has an outer diameter of 6-9 μm and an inner diameter of 1-3 μm.

5. The negative electrode material of claim 1, wherein, The solid particulate silicon-based material has a specific surface area of 2.4 m 2 / g ~ 3.6 m 2 / g; and / or the negative electrode material has a specific surface area of 3 m 2 / g ~ 5 m 2 / g.

6. The negative electrode material of claim 2, wherein, The SiO x The solid particulate silicon-based material is an amorphous material, the surface of which is coated with a carbon layer.

7. The negative electrode material of claim 1, wherein, The solid particle silicon-based material is spherical or spheroid.

8. The negative electrode material according to any one of claims 1 to 7, characterized in that, The micro-powder silicon-based material has a median particle size of 0.1-0.5 μm.

9. The negative electrode material according to any one of claims 1 to 7, characterized by, The mass ratio of the solid particle silicon-based material to the micro-powder silicon-based material is 4:1-2.

10. The negative electrode material according to any one of claims 1 to 7, characterized by, The negative electrode material further comprises graphite, and the median particle size of the graphite is greater than the outer diameter of the solid particle silicon-based material.

11. The negative electrode material according to claim 10, characterized in that, The median particle size of the graphite is 10-20 μm.

12. The negative electrode material according to any one of claims 1 to 7, characterized by, The theoretical mass specific capacity of the negative electrode material is 1100-1400 mAh / g.

13. A method for preparing a negative electrode material, characterized in that, The method comprises: providing solid particle silicon-based material with ring structure and micro-powder silicon-based material; mixing the solid particle silicon-based material and the micro-powder silicon-based material to fill the interspace in the hollow ring of the solid particle silicon-based material and / or between the solid particle silicon-based materials.

14. The method of claim 13, wherein the method is characterized by: The method further comprises preparing the solid particle silicon-based material, comprising: providing silicon-based material initial material; crushing the silicon-based material initial material to obtain crushed particles; preparing the crushed particles into a suspension solution, and performing spray drying treatment on the suspension solution to obtain solid particle silicon-based material with ring structure.

15. The method of claim 14, wherein the method further comprises a step of mixing the carbon material and the metal compound. The spray drying treatment comprises atomizing the suspension solution and then injecting it into a hot air stream for drying, and the temperature of the drying air is 90-110 ℃, and the solution flow rate is 80-120 L / min.

16. The method of claim 14, wherein the method is characterized by: The method further comprises pre-lithiation treatment on the solid particle silicon-based material.

17. The method of claim 14, wherein the method further comprises: The method further comprises a step of carbon-coating the solid particle silicon-based material with ring structure.

18. A negative electrode sheet characterized by comprising: The electrode assembly comprises:

19. The negative electrode sheet according to claim 18, wherein the negative electrode sheet according to any one of claims 18-20; 20. The negative electrode sheet according to claim 18, wherein a separator film covering at least one side of the negative electrode sheet.

21. An electrode assembly, characterized by, The electrode assembly comprises: the electrode assembly according to claim 21. The battery comprises:

22. A battery, characterized by the battery according to claim 22.

23. An electrical device, comprising: ​

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