Silicon-based material and preparation method thereof, lithium ion battery monomer, battery device and power utilization device

Abstract

The invention provides a silicon-based material and a preparation method thereof, a lithium ion battery monomer, a battery device and a power utilization device, the silicon-based material comprises a porous carbon matrix and silicon nanoparticles located in pores of the porous carbon matrix, the surface of each silicon nanoparticle is provided with a silicon oxide passivation layer formed through a passivation reaction, the ratio of the ID / IG of the silicon-based material to the ID / IG of the porous carbon matrix before the passivation reaction is (0.95-1.05): 1; the mass multiple of the Si element and the C element in the silicon-based material is recorded as A, the mass multiple of the Si element and the C element before the passivation reaction is recorded as B, and the ratio of A to B is (0.95-1.05): 1. According to the invention, the thermal safety performance, the cycle performance and the rate capability of the lithium ion battery monomer can be improved.

Description

Technical Field

[0001] The present disclosure relates to a silicon-based material and a preparation method thereof, a lithium-ion battery cell, a battery device, and an electrical device. Background Art

[0002] In recent years, with the widespread application of lithium-ion battery cells in energy storage power systems such as hydropower, thermal power, wind power and solar power stations, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace and other fields, the energy density and cycle performance of lithium-ion battery cells using graphite as the negative electrode active material can no longer meet the growing technical requirements. Silicon has a moderate lithium insertion potential (0.4V vs. Li / Li + ) and a high theoretical specific capacity (approximately 3579 mAh / g), making it a standout among candidates for new negative electrode active materials. However, silicon expands by as much as 300% during the charge and discharge cycles of lithium-ion battery cells, and it is difficult to form a stable solid electrolyte interface (SEI) film on the silicon surface, resulting in a rapid capacity decay in lithium-ion battery cells. Summary of the Invention

[0003] The present disclosure provides a silicon-based material and a preparation method thereof, a lithium-ion battery cell, a battery device and an electrical device. The lithium-ion battery cell using the silicon-based material has high thermal safety performance, good cycle performance and good rate performance.

[0004] In a first aspect, the present disclosure provides a silicon-based material, comprising a porous carbon matrix and silicon nanoparticles located in the pores of the porous carbon matrix, wherein the surface of the silicon nanoparticles has a silicon oxide passivation layer formed by a passivation reaction. D / I G I of the porous carbon matrix before the passivation reaction D / I G The ratio is (0.95-1.05):1,I D Indicates that the Raman spectrum is at 1350±50cm -1 The D peak intensity at I G Indicates that the Raman spectrum is at 1580±50cm -1 the mass multiple of Si element and C element in the silicon-based material is recorded as A, the mass multiple of Si element and C element before the passivation reaction is recorded as B, A: B is (0.95-1.05): 1.

[0005] The surface of silicon nanoparticles has a silicon oxide passivation layer formed by a passivation reaction, which can reduce the surface activity of silicon nanoparticles, reduce electrolyte side reactions, and alleviate the problem of negative electrode pulverization caused by the volume expansion of silicon nanoparticles. As a result, lithium-ion battery cells using silicon-based materials can have high thermal safety performance, good cycle performance and good rate performance.

[0006] Silicon-based materials I D / I G I of porous carbon matrix before passivation reaction D / I G The ratio is (0.95-1.05):1, the mass multiple of Si element and C element in the silicon-based material is recorded as A, and the mass multiple of Si element and C element before the passivation reaction is recorded as B. A:B is (0.95-1.05):1, which shows that the passivation reaction will not affect the intrinsic properties of the porous carbon matrix, nor will it affect the stability of the silicon-based material.

[0007] In some embodiments, the silicon-based material contains an oxygen content of 2% to 34% by weight. A suitable silicon oxide passivation layer can provide the silicon-based material with both high capacity and high electronic conductivity and a low specific surface area. This reduces electrolyte side reactions and alleviates negative electrode pulverization caused by volume expansion of silicon nanoparticles, thereby further improving the thermal safety, cycling performance, and rate capability of lithium-ion battery cells.

[0008] In some embodiments, the mass content of Si element in the silicon-based material is 25%-60%.

[0009] In some embodiments, the mass content of the C element in the silicon-based material is 20%-60%.

[0010] In some embodiments, the thickness of the silicon oxide passivation layer is less than or equal to 0.4 times the particle size of the silicon nanoparticles having the silicon oxide passivation layer on their surfaces. An appropriate amount of silicon oxide passivation layer can enable silicon-based materials to have both high capacity and high electronic conductivity and low specific surface area, reducing electrolyte side reactions and alleviating negative electrode pulverization caused by volume expansion of silicon nanoparticles, thereby further improving the thermal safety, cycling performance, and rate performance of lithium-ion battery cells.

[0011] In some embodiments, the silicon nanoparticles having a silicon oxide passivation layer on their surfaces have a particle size of 0.4 nm to 45 nm.

[0012] In some embodiments, the pore size of the porous carbon matrix is ​​0.5 nm to 50 nm.

[0013] In some embodiments, the specific surface area of ​​the porous carbon matrix is ​​200 m 2 / g-3000m2 / g.

[0014] In some embodiments, the volume distribution particle size Dv50 of the silicon-based material is 0.8 μm-20 μm.

[0015] In some embodiments, the specific surface area of ​​the silicon-based material is 0.5 m 2 / g-4m 2 / g.

[0016] In a second aspect, the present disclosure provides a method for preparing a silicon-based material, comprising the following steps: providing a porous carbon matrix; depositing silicon nanoparticles in the pores of the porous carbon matrix by vapor deposition to obtain a silicon-carbon material intermediate; subjecting the obtained silicon-carbon material intermediate to a passivation reaction with water in a closed environment and forming a silicon oxide passivation layer on the surface of the silicon nanoparticles to obtain a silicon-based material, wherein the temperature of the passivation reaction is 80°C-300°C, and the mass of the water is 3%-60% of the mass of the silicon-carbon material intermediate.

[0017] The present invention uses water with a mass fraction of 3%-60% compared to the silicon-carbon material intermediate as a conversion agent, and passivates the silicon nanoparticles at a low temperature of 80°C-300°C. This will not affect the intrinsic properties of the silicon-carbon material intermediate, and will form an in-situ silicon oxide passivation layer on the surface of the silicon nanoparticles. It can also improve the electronic conductivity of the silicon-carbon material intermediate and reduce the specific surface area of ​​the silicon-carbon material intermediate, thereby reducing electrolyte side reactions and alleviating the negative electrode pulverization problem caused by the volume expansion of silicon nanoparticles, thereby enabling lithium-ion battery cells using silicon-based materials to have high thermal safety performance, good cycle performance, and good rate performance. In addition, the preparation method of the silicon-based material provided by the present invention has a simple process route, mild reaction conditions, and the prepared silicon-based material is highly controllable, and the coating amount of the silicon oxide passivation layer is easy to adjust.

[0018] In some embodiments, the temperature of the passivation reaction is 120°C-220°C.

[0019] In some embodiments, the mass of the water is 15%-40% of the mass of the silicon-carbon material intermediate.

[0020] In some embodiments, the passivation reaction time is 0.5h-48h, optionally 2h-24h.

[0021] In some embodiments, the pore size of the porous carbon matrix is ​​0.5 nm to 50 nm.

[0022] In some embodiments, the specific surface area of ​​the porous carbon matrix is ​​200 m 2 / g-3000m 2 / g.

[0023] In some embodiments, the silicon nanoparticles have a particle size of 0.4 nm to 40 nm.

[0024] In some embodiments, the step of depositing silicon nanoparticles in the pores of the porous carbon matrix by vapor deposition to obtain a silicon-carbon material intermediate includes the following steps: decomposing silane gas by chemical vapor deposition to deposit silicon nanoparticles in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate.

[0025] In some embodiments, the vapor deposition temperature is 400°C-800°C.

[0026] In some embodiments, the silane gas includes one or more of monosilane, disilane, dichlorosilane, trichlorosilane, tetrafluorosilane, hexamethyldisilane, methylvinyldichlorosilane, dimethylvinylchlorosilane, vinyltrichlorosilane, and tris(trimethylsilyl)silane.

[0027] In a third aspect, the present disclosure provides a lithium-ion battery cell comprising a positive electrode sheet, a negative electrode sheet, and an isolating member, wherein the isolating member is located between the positive electrode sheet and the negative electrode sheet, and the negative electrode sheet comprises the silicon-based material of the first aspect or the silicon-based material prepared by the preparation method of the second aspect.

[0028] In a fourth aspect, the present disclosure provides a battery device comprising a plurality of lithium-ion battery cells according to the third aspect.

[0029] In a fifth aspect, the present disclosure provides an electrical device comprising the lithium-ion battery cell of the third aspect or the battery device of the fourth aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] To more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following briefly introduces the drawings required for use in the embodiments of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on the drawings without inventive effort.

[0031] Figure 1 A schematic diagram showing a lithium-ion battery cell provided by some embodiments of the present disclosure.

[0032] Figure 2 A schematic diagram of an electrical device provided by some embodiments of the present disclosure is shown.

[0033] Figure 3 The Raman spectra of the silicon-based materials prepared in Example 1 and Comparative Example 1 are shown.

[0034] Figure 4X-ray photoelectron spectroscopy (XPS) graphs of the silicon-based materials prepared in Example 1 and Comparative Example 1 are shown.

[0035] Figure 5 The X-ray diffraction (XRD) patterns of the silicon-based materials prepared in Example 1 and Comparative Example 1 are shown.

[0036] Figure 6 Thermogravimetric analysis (TG) graphs of the fully charged negative electrode sheets of Example 1 and Comparative Example 1 are shown.

[0037] Figure 7 The differential scanning calorimetry (DSC) graphs of the fully charged negative electrode sheets of Example 1 and Comparative Example 1 are shown.

[0038] Figure 8 The thermal runaway gas generation diagrams of the lithium-ion battery cells prepared in Example 1 and Comparative Example 1 are shown.

[0039] Figure 9 The figure shows the discharge capacity of the lithium-ion battery cell prepared in Example 1 at different rates.

[0040] Figure 10 The figure shows the discharge capacity of the lithium-ion battery cell prepared in Comparative Example 1 at different rates. DETAILED DESCRIPTION

[0041] Below, with appropriate reference to the accompanying drawings, the embodiments of the silicon-based material and its preparation method, lithium-ion battery cells, battery devices, and electrical devices disclosed herein are described in detail. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there may be cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to limit the subject matter described in the claims.

[0042] " scope " disclosed in the present disclosure is limited in the form of lower limit and upper limit, and given range is limited by selecting a lower limit and an upper limit, and selected lower limit and upper limit define the boundary of special scope.The scope that this mode limits can be to include end value or not include end value, and can be combined arbitrarily, and promptly any lower limit can form a scope with any upper limit combination.For example, if the scope of 60-120 and 80-110 is listed for specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected.In addition, if the minimum range value 1 and 2 listed, and if the maximum range value 3,4 and 5 listed, then the following scope can all be expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5.In the present disclosure, unless otherwise specified, numerical range " ab " represents the abbreviation of any real number combination between a and b, and wherein a and b are all real numbers. For example, a numerical range of "0-5" indicates that all real numbers between "0-5" are listed herein, and "0-5" is simply an abbreviation for these numerical combinations. Furthermore, when a parameter is expressed as an integer ≥ 2, this is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0043] Unless otherwise specified, all embodiments and optional embodiments of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present disclosure.

[0044] Unless otherwise specified, all technical features and optional technical features of the present disclosure can be combined with each other to form new technical solutions, and such technical solutions should be considered to be included in the disclosure content of the present disclosure.

[0045] Unless otherwise specified, all steps of the present disclosure may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0046] If not otherwise specified, in the present disclosure, the terms "first", "second", etc. are used to distinguish different objects rather than to describe a specific order or a primary-secondary relationship.

[0047] In the present disclosure, the terms "plurality" and "multiplicity" refer to two or more.

[0048] In the description of the embodiments of the present disclosure, if there is no special indication, the first feature is "on" or "under" the second feature, which can be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature can be "above", "over" and "on" the second feature, which can be that the first feature is directly above or obliquely above the second feature, or only means that the horizontal height of the first feature is higher than that of the second feature. The first feature can be "under", "below" and "underneath" the second feature, which can be that the first feature is directly below or obliquely below the second feature, or only means that the horizontal height of the first feature is less than that of the second feature.

[0049] Unless otherwise specified, the test temperature of each parameter mentioned in the present disclosure is 25°C.

[0050] The lithium ion battery cell mentioned in the embodiments of the present disclosure can realize the function of charging and discharging alone. The lithium ion battery cell can be in the shape of a cylinder, a cuboid or other shapes, which are not limited in the embodiments of the present disclosure. For example, Figure 1 is a lithium ion battery cell 5 in the shape of a cuboid as an example.

[0051] The battery apparatus mentioned in the embodiments of the present disclosure can include one or more battery cell assemblies for providing voltage and capacity. The battery cell assembly can include a plurality of lithium ion battery cells connected in series, in parallel or in a mixed connection through a busbar component.

[0052] In some embodiments, the battery cell assembly is usually formed by arranging a plurality of lithium ion battery cells.

[0053] As an example, the battery cell assembly can be a battery module formed by arranging and fixing a plurality of lithium ion battery cells into an independent module. As an example, the battery module can be formed by bundling a plurality of lithium ion battery cells with a cable tie.

[0054] In some embodiments, the battery apparatus can be a battery pack including a box body and one or more battery cell assemblies accommodated in the box body.

[0055] As an example, the battery cell assembly can be a battery module, which can be accommodated in the box body by fixing the battery module in the box body.

[0056] As an example, the battery cell assembly can also be accommodated in the box body by directly fixing a plurality of lithium ion battery cells in the box body.

[0057] As an example, the housing may include a first housing and a second housing. The first housing and the second housing engage to form an enclosed space within the housing to house the battery cell assembly. Enclosed here means covered or closed, and can be either sealed or unsealed. The first housing may be a top cover or a bottom plate.

[0058] As an example, the box may include a top cover, a frame, and a bottom plate, wherein the top cover and the bottom plate are respectively connected to the frame to form a closed space inside the box to accommodate the battery cell assembly.

[0059] In some embodiments, the box body can be used as a part of the chassis structure of the vehicle. For example, part of the box body can become at least a part of the floor of the vehicle, or part of the box body can become at least a part of the cross beam and longitudinal beam of the vehicle.

[0060] The technical solutions described in the embodiments of this disclosure are applicable to various electrical devices using lithium-ion battery cells and battery devices, including, but not limited to, mobile devices (e.g., mobile phones, tablet computers, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc. Lithium-ion battery cells and battery devices are used to store or provide electrical energy.

[0061] Figure 2 1 is a schematic diagram of an exemplary electric device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.

[0062] The lithium-ion battery cells provided in the embodiments of the present disclosure include an electrode assembly and an outer packaging, which can be used to encapsulate the electrode assembly. The outer packaging can be a hard shell, such as a hard plastic shell, an aluminum shell, a steel shell, etc. The outer packaging can also be a soft package, such as a bag-type soft package. The material of the soft package can be plastic, such as one or more of aluminum-plastic film, polypropylene, polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0063] Silicon-carbon material is a commonly used silicon-based material, which is usually formed by depositing silicon in a porous carbon matrix. Compared with pure silicon, silicon-carbon material can have smaller volume expansion and higher electronic conductivity. However, the silicon in the silicon-carbon material also has the problems of high reactivity, large volume expansion, and poor electronic conductivity. The volume expansion of silicon can be reduced by surface passivation treatment of the silicon in the silicon-carbon material. However, the surface passivation treatment currently used is usually carried out in a high-temperature environment, which will affect the performance of the porous carbon matrix itself, resulting in the performance of the silicon-carbon material obtained by passivation treatment often failing to meet expectations.

[0064] Based on this, the present disclosure provides a method for preparing silicon-based materials, which will not affect the intrinsic properties of the material before passivation, and can alleviate the problem of negative electrode pulverization caused by the volume expansion of silicon nanoparticles, thereby enabling lithium-ion battery cells using silicon-based materials to have high thermal safety performance, good cycle performance and good rate performance.

[0065] The preparation method of the silicon-based material provided in the embodiment of the present disclosure includes the following steps: providing a porous carbon matrix; depositing silicon nanoparticles in the pores of the porous carbon matrix by vapor deposition to obtain a silicon-carbon material intermediate; passivating the obtained silicon-carbon material intermediate with water in a closed environment and forming a silicon oxide passivation layer on the surface of the silicon nanoparticles to obtain a silicon-based material, the temperature of the passivation reaction is 80°C-300°C, and the mass of water is 3%-60% of the mass of the silicon-carbon material intermediate.

[0066] The preparation method of the silicon-based material provided by the present disclosure uses water as a transformation agent and passivates the silicon nanoparticles of the silicon-carbon material intermediate in a low-temperature environment of 80°C-300°C, which has the advantages of low cost, easy production, and no pollution. The use of water as a transformation agent will not introduce other disturbing elements into the prepared silicon-based material, and can form a silicon oxide passivation layer in situ on the surface of the silicon nanoparticles of the silicon-carbon material intermediate. Passivating the silicon-carbon material intermediate in a low-temperature environment of 80°C-300°C will not affect the intrinsic properties of the silicon-carbon material intermediate, such as not affecting the graphitization degree of the porous carbon matrix and not changing the morphology of the silicon nanoparticles; passivating the silicon-carbon material intermediate in a low-temperature environment of 80°C-300°C will not affect the stability of the prepared silicon-based material.

[0067] During the passivation reaction, the mass of water is 3% to 60% of the mass of the silicon-carbon material intermediate. This allows the coating of the silicon oxide passivation layer to be adjusted, preventing the complete conversion of the silicon nanoparticles into silicon oxide. Complete conversion of silicon nanoparticles into silicon oxide reduces the specific capacity and electronic conductivity of the resulting silicon-based material, hindering the transport of lithium ions within the material and impacting the cycling and rate performance of lithium-ion battery cells.

[0068] Therefore, the present disclosure adopts water with a mass fraction of 3%-60% compared with the silicon-carbon material intermediate as a conversion agent, and passivates the silicon nanoparticles in a low temperature environment of 80°C-300°C. This will not affect the intrinsic properties of the silicon-carbon material intermediate, and will form a silicon oxide passivation layer in situ on the surface of the silicon nanoparticles. It can also improve the electronic conductivity of the silicon-carbon material intermediate and reduce the specific surface area of ​​the silicon-carbon material intermediate, thereby reducing electrolyte side reactions and alleviating the negative electrode pulverization problem caused by the volume expansion of silicon nanoparticles, so that the lithium-ion battery monomer using silicon-based materials can have high thermal safety performance, good cycle performance and good rate performance. In addition, the preparation method of the silicon-based material provided by the present disclosure has a simple process route, mild reaction conditions, and the prepared silicon-based material is highly controllable, and the coating amount of the silicon oxide passivation layer is easy to adjust.

[0069] By adjusting the mass fraction of water, the passivation reaction temperature, and the passivation reaction time parameters, the coating amount of the silicon oxide passivation layer and the mass content of the O element in the prepared silicon-based material can be adjusted.

[0070] The higher the mass fraction of water, the higher the passivation reaction temperature, and the longer the passivation reaction time, the greater the coating amount of the silicon oxide passivation layer, and the greater the mass content of the O element in the prepared silicon-based material.

[0071] The temperature of the passivation reaction is 80°C-300°C, for example, it can be 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, or a range consisting of any of the above values.

[0072] Optionally, the temperature of the passivation reaction can be 100℃-240℃, 110℃-240℃, 120℃-240℃, 100℃-220℃, 110℃-220℃, 120℃-220℃, 100℃-200℃, 110℃-200℃, 120℃-200℃, 100℃-180℃, 110℃-180℃, 120℃-180℃.

[0073] This can better reduce the impact of the passivation treatment on the intrinsic properties of the silicon-carbon material intermediate.

[0074] The mass of water is 3%-60% of the mass of the silicon-carbon material intermediate, for example, it can be 3%, 4%, 5%, 6%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or a range consisting of any of the above values.

[0075] Optionally, the mass of water can be 5%-40%, 8%-40%, 10%-40%, 12%-40%, 15%-40%, 5%-36%, 8%-36%, 10%-36%, 12%-36%, 15%-36%, 5%-32%, 8%-32%, 10%-32%, 12%-32%, 15%-32%, 5%-30%, 8%-30%, 10%-30%, 12%-30%, 15%-30% of the mass of the silicon-carbon material intermediate.

[0076] In some embodiments, the passivation reaction time can be 0.5h-48h, for example, it can be 0.5h, 1h, 2h, 3h, 4h, 5h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h, 48h, or a range consisting of any of the above values.

[0077] Optionally, the passivation reaction time can be 2h-24h, 4h-24h, 6h-24h, 2h-20h, 4h-20h, 6h-20h, 2h-18h, 4h-18h, 6h-18h, 2h-16h, 4h-16h, 6h-16h.

[0078] In some embodiments, the pore size of the porous carbon matrix can be 0.5nm-50nm, for example, it can be 0.5nm, 1nm, 2nm, 4nm, 6nm, 8nm, 10nm, 12nm, 14nm, 16nm, 18nm, 20nm, 22nm, 24nm, 26nm, 28nm, 30nm, 32nm, 34nm, 36nm, 38nm, 40nm, 42nm, 44nm, 46nm, 48nm, 50nm, or a range consisting of any of the above values.

[0079] In some embodiments, the specific surface area of ​​the porous carbon matrix can be 200 m 2 / g-3000m 2 / g, for example, 200m 2 / g, 400m2 / g、600m 2 / g、800m 2 / g、1000m 2 / g、1200m 2 / g、1400m 2 / g、1600m 2 / g、1800m 2 / g、2000m 2 / g、2200m 2 / g、2400m 2 / g、2600m 2 / g、2800m 2 / g、3000m 2 / g, or any range consisting of the above values.

[0080] In some embodiments, the silicon nanoparticles formed by deposition may be amorphous silicon.

[0081] In some embodiments, before the passivation reaction, the particle size of the deposited silicon nanoparticles is 0.4 nm-40 nm, for example, 0.4 nm, 1 nm, 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, or a range consisting of any of the above values.

[0082] In some embodiments, the step of depositing silicon nanoparticles in the pores of the porous carbon matrix by vapor deposition to obtain a silicon-carbon material intermediate includes the following steps: decomposing silane gas by chemical vapor deposition to deposit silicon nanoparticles in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate.

[0083] Optionally, the temperature of vapor deposition can be 400℃-800℃, for example, it can be 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 560℃, 580℃, 600℃, 620℃, 640℃, 660℃, 680℃, 700℃, 720℃, 740℃, 760℃, 780℃, 800℃, or a range consisting of any of the above values.

[0084] Optionally, the silane gas includes silane, and the silane may include one or more of monosilane, disilane, dichlorosilane, trichlorosilane, tetrafluorosilane, hexamethyldisilane, methylvinyldichlorosilane, dimethylvinylchlorosilane, vinyltrichlorosilane, and tris(trimethylsilyl)silane.

[0085] Optionally, the silane gas may further include one or more of nitrogen, argon, and helium.

[0086] Optionally, the volume proportion of silane in the silane gas may be 10%-50%.

[0087] Alternatively, the deposition apparatus may be a rotary kiln or a fluidized bed.

[0088] Optionally, the porous carbon matrix may include one or more of coconut shell carbon, resin carbon, and petroleum coke carbon.

[0089] The embodiments of the present disclosure also provide a silicon-based material.

[0090] The silicon-based material provided by the embodiment of the present disclosure includes a porous carbon matrix and silicon nanoparticles located in the pores of the porous carbon matrix. The surface of the silicon nanoparticles has a silicon oxide passivation layer formed by a passivation reaction. D / I G I of porous carbon matrix before passivation reaction D / I G The ratio is (0.95-1.05):1,I D Indicates that the Raman spectrum is at 1350±50cm -1 The D peak intensity at I G Indicates that the Raman spectrum is at 1580±50cm -1 The G peak intensity at ; the mass multiple of Si element and C element in the silicon-based material is recorded as A, the mass multiple of Si element and C element before passivation reaction is recorded as B, and A:B is (0.95-1.05):1.

[0091] The surface of silicon nanoparticles has a silicon oxide passivation layer formed by a passivation reaction, which can reduce the surface activity of silicon nanoparticles, reduce electrolyte side reactions, and alleviate the problem of negative electrode pulverization caused by the volume expansion of silicon nanoparticles. As a result, lithium-ion battery cells using silicon-based materials can have high thermal safety performance, good cycle performance and good rate performance.

[0092] Silicon-based materials I D / I G I of porous carbon matrix before passivation reaction D / I G The ratio is (0.95-1.05):1, the mass multiple of Si element and C element in the silicon-based material is recorded as A, and the mass multiple of Si element and C element before the passivation reaction is recorded as B. A:B is (0.95-1.05):1, which shows that the passivation reaction will not affect the intrinsic properties of the porous carbon matrix, nor will it affect the stability of the silicon-based material.

[0093] Silicon-based materials I D / I GI of porous carbon matrix before passivation reaction D / I G The ratio is (0.95-1.05):1, for example, it can be 0.95:1, 0.952:1, 0.954:1, 0.956:1, 0.958:1, 0.96:1, 0.962:1, 0.964:1, 0.966:1, 0.968:1, 0.97:1, 0.972:1, 0.974:1, 0.976:1, 0.978:1, 0.98:1, 0.982:1, 0.984:1, 0.986:1, 0.988:1, 0.99:1, 0.992:1, 0.994:1, 0.996:1, 0.99 1, 1.042:1, 1.044:1, 1.046:1, 1.048:1, 1.05:1, or a range consisting of any of the foregoing.

[0094] Optionally, the I of the silicon-based material D / I G I of porous carbon matrix before passivation reaction D / I G The ratios are (0.96-1.04):1, (0.97-1.03):1.

[0095] The mass multiple of Si element and C element in the silicon-based material is recorded as A, and the mass multiple of Si element and C element before the passivation reaction is recorded as B. A:B is (0.95-1.05):1, for example, it can be 0.95:1, 0.952:1, 0.954:1, 0.956:1, 0.958:1, 0.96:1, 0.962:1, 0.964:1, 0.966:1, 0.968:1, 0.97:1, 0.972:1, 0.974:1, 0.976:1, 0.978:1, 0.98:1, 0.982:1, 0.984:1, 0.986:1, 0.988:1, 0.99:1, 0.992: 1, 0.994:1, 0.996:1, 0.998:1, 1, 1.002:1, 1.004:1, 1.006:1, 1.008:1, 1.01:1, 1.012:1, 1.014:1, 1.016:1, 1.018:1, 1.02:1, 1.022:1, 1.024:1, 1.026:1, 1.028:1, 1.03:1, 1.032:1, 1.034:1, 1.036:1, 1.038:1, 1.04:1, 1.042:1, 1.044:1, 1.046:1, 1.048:1, 1.05:1, or a range consisting of any of the above values.

[0096] Optionally, A:B is (0.96-1.04):1, (0.97-1.03):1, (0.98-1.02):1, (0.99-1.01):1, (0.992-1.008):1, (0.994-1.006):1.

[0097] In some embodiments, the mass content of the O element in the silicon-based material can be 2%-34%, for example, it can be 2%, 3%, 4%, 5%, 6%, 8%, 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, or a range consisting of any of the above values.

[0098] An appropriate amount of silicon oxide passivation layer can enable silicon-based materials to have high electronic conductivity and low specific surface area while having high capacity, reduce electrolyte side reactions, and alleviate the problem of negative electrode pulverization caused by the volume expansion of silicon nanoparticles, thereby better improving the thermal safety performance, cycle performance and rate performance of lithium-ion battery cells.

[0099] Optionally, the mass content of O element in the silicon-based material can be 4%-34%, 6%-34%, 8%-34%, 10%-34%, 12%-34%, 14%-34%, 4%-32%, 6%-32%, 8%-32%, 10%-32%, 12%-32%, 14%-32%, 4%-30%, 6%-30%, 8%-30%, 10%-30%, 12%-30%, 14%-30%, 4%-28%, 6%-28%, 8%-28%, 10%-28%, 12%-28%, 14%-28%, 4%-26%, 6%-26%, 8%-26%, 10%-26%, 12%-26%, 14%-36%.

[0100] In some embodiments, the mass content of Si element in the silicon-based material can be 25%-60%, for example, it can be 25%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or a range consisting of any of the above values.

[0101] In some embodiments, the mass content of the C element in the silicon-based material can be 20%-60%, for example, it can be 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, 40%, 42%, 44%, 46%, 48%, 50%, 52%, 54%, 56%, 58%, 60%, or a range consisting of any of the above values.

[0102] The mass content of O element in silicon-based materials can be tested with reference to GB / T 38976-2020.

[0103] The mass content of C element in silicon-based materials can be tested with reference to GB / T 32573-2016.

[0104] The mass content of Si element in silicon-based materials can be tested with reference to GB / T 20975.5-2020.

[0105] In some embodiments, the thickness of the silicon oxide passivation layer may be less than or equal to 0.4 times the particle size of the silicon nanoparticles having the silicon oxide passivation layer on their surfaces.

[0106] An appropriate amount of silicon oxide passivation layer can enable silicon-based materials to have high electronic conductivity and low specific surface area while having high capacity, reduce electrolyte side reactions, and alleviate the problem of negative electrode pulverization caused by the volume expansion of silicon nanoparticles, thereby better improving the thermal safety performance, cycle performance and rate performance of lithium-ion battery cells.

[0107] Optionally, the thickness of the silicon oxide passivation layer can be 0.01 times to 0.4 times, 0.01 times to 0.35 times, 0.01 times to 0.3 times, 0.01 times to 0.25 times, 0.01 times to 0.2 times, 0.02 times to 0.4 times, 0.02 times to 0.35 times, 0.02 times to 0.3 times, 0.02 times to 0.25 times, 0.02 times to 0.2 times, 0.05 times to 0.4 times, 0.05 times to 0.35 times, 0.05 times to 0.3 times, 0.05 times to 0.25 times, 0.05 times to 0.2 times,

[0108] The thickness of the silicon oxide passivation layer refers to the distance between the inner surface and the outer surface of the silicon oxide passivation layer. The distance between the inner surface and the outer surface of the silicon oxide passivation layer can be measured at multiple positions (for example, more than 10) in the image of the cross-section of the silicon-based material and then the average value is taken.

[0109] In some embodiments, the particle size of the silicon nanoparticles having a silicon oxide passivation layer on the surface can be 0.4 nm-45 nm, for example, 0.4 nm, 0.5 nm, 1 nm, 2 nm, 4 nm, 6 nm, 8 nm, 10 nm, 12 nm, 14 nm, 16 nm, 18 nm, 20 nm, 22 nm, 24 nm, 26 nm, 28 nm, 30 nm, 32 nm, 34 nm, 36 nm, 38 nm, 40 nm, 42 nm, 45 nm, or a range consisting of any of the above values.

[0110] In some embodiments, the pore size of the porous carbon matrix can be 0.5nm-50nm, for example, it can be 0.5nm, 1nm, 2nm, 4nm, 6nm, 8nm, 10nm, 12nm, 14nm, 16nm, 18nm, 20nm, 22nm, 24nm, 26nm, 28nm, 30nm, 32nm, 34nm, 36nm, 38nm, 40nm, 42nm, 44nm, 46nm, 48nm, 50nm, or a range consisting of any of the above values.

[0111] In some embodiments, the specific surface area of ​​the porous carbon matrix can be 200 m 2 / g-3000m 2 / g, for example, 200m 2 / g, 400m 2 / g、600m 2 / g、800m 2 / g、1000m 2 / g、1200m 2 / g、1400m 2 / g、1600m 2 / g、1800m 2 / g、2000m 2 / g、2200m 2 / g、2400m 2 / g、2600m 2 / g、2800m 2 / g、3000m 2 / g, or any range consisting of the above values.

[0112] In some embodiments, the volume distribution particle size Dv50 of the silicon-based material can be 0.8μm-20μm, for example, it can be 0.8μm, 1μm, 2μm, 4μm, 6μm, 8μm, 10μm, 12μm, 14μm, 16μm, 18μm, 20μm, or a range consisting of any of the above values.

[0113] In some embodiments, the specific surface area of ​​the silicon-based material can be 0.5 m 2 / g-4m 2 / g, for example, 0.5m 2 / g, 0.6m 2 / g, 0.8m 2 / g、1m 2 / g, 1.2m 2 / g, 1.4m 2 / g, 1.6m 2 / g, 1.8m 2 / g, 2m 2 / g, 2.2m 2 / g, 2.4m 2 / g, 2.6m 2 / g, 2.8m 2 / g、3m 2 / g, 3.2m 2 / g, 3.4m 2 / g, 3.6m 2 / g, 3.8m 2 / g、4m 2 / g, or any range consisting of the above values.

[0114] The silicon-based material provided in the present disclosure is prepared by the method for preparing the silicon-based material disclosed in the present disclosure.

[0115] The present disclosure also provides a lithium-ion battery cell, which includes a positive electrode sheet, a negative electrode sheet, and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet.

[0116] [Negative electrode]

[0117] In some embodiments, the negative electrode sheet may include a negative electrode current collector and a negative electrode film layer located on at least one surface of the negative electrode current collector, wherein the negative electrode film layer includes a negative electrode active material, wherein the negative electrode active material includes a silicon-based material prepared by the preparation method of the present disclosure. The negative electrode current collector has two surfaces that oppose each other in its thickness direction, and the negative electrode film layer is disposed on either or both of the two opposing surfaces of the negative electrode current collector.

[0118] In some embodiments, the negative electrode film layer may further include other negative electrode active materials, for example, including but not limited to one or more of natural graphite, artificial graphite, soft carbon, hard carbon, and lithium titanate.

[0119] In some embodiments, the negative electrode film layer may further include a negative electrode binder, which may include butadiene styrene rubber (SBR), sodium carboxymethyl cellulose, water-soluble unsaturated resin SR-1B, polyacrylic acid, polymethacrylic acid, sodium polyacrylate, polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), carboxymethyl chitosan (CMCS), methyl vinyl silicone rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), thermoplastic styrene butadiene rubber (SBS), isoprene rubber, butadiene rubber (BR), ethyl cellulose, fluororubber, and one or more of acrylate rubber.

[0120] In some embodiments, the negative electrode film layer may further include a negative electrode conductive agent, which may include but is not limited to one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor grown carbon fibers (VGCF).

[0121] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. As examples of metal foils, copper foil, copper alloy foil, nickel foil, nickel alloy foil, aluminum foil, and aluminum alloy foil may be used. As examples of three-dimensional porous current collectors, copper mesh, nickel mesh, aluminum mesh, foam copper, foam nickel, and foam aluminum may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include, but is not limited to, one or more of copper, copper alloy, aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene, and polyethylene.

[0122] The negative electrode film layer is typically formed by coating the negative electrode slurry onto the negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing the negative electrode active material, negative electrode conductive agent, negative electrode binder, and other optional additives in a solvent and stirring them evenly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0123] [Positive electrode]

[0124] In some embodiments, the positive electrode sheet may include a positive electrode current collector and a positive electrode film layer located on at least one surface of the positive electrode current collector, wherein the positive electrode film layer includes a positive electrode active material. The positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode film layer is disposed on either or both of the two opposing surfaces of the positive electrode current collector.

[0125] In some embodiments, the positive electrode active material may include one or more of lithium transition metal oxides and modified materials thereof, lithium-containing phosphates and modified materials thereof.

[0126] Optionally, examples of lithium transition metal oxides may include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and lithium manganese-rich based materials.

[0127] Optionally, examples of lithium-containing phosphates may include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium iron manganese phosphate, and a composite material of lithium iron manganese phosphate and carbon.

[0128] In some embodiments, in order to further improve the energy density of lithium-ion battery cells, the positive electrode active material may include a general formula of Li a Ni b Co c M d O e A f One or more lithium transition metal oxides and modified materials thereof. 0.8≤a≤1.2, 0.5≤b<1, 0<c<1, 0<d<1, 1≤e≤2, 0≤f≤1, M may include one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A may include one or more of N, F, S and Cl.

[0129] As an example, the positive electrode active material may include but is not limited to LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3O2 (abbreviated as NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (abbreviated as NCM523), LiNi 0.5 Co 0.25 Mn 0.25 O2 (abbreviated as NCM211), LiNi 0.6 Co 0.2 Mn 0.2 O2 (abbreviated as NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (abbreviated as NCM811), LiNi 0.83 Mn 0.08 Co 0.07 O2 (abbreviated as Ni83), LiNi 0.90 Mn 0.05 Co 0.05 O2 (abbreviated as Ni90), LiNi 0.94 Mn 0.03 Co 0.03 O2 (abbreviated as Ni94), LiNi 0.96 Co 0.02 Mn 0.02 O2 (abbreviated as Ni96), LiNi 0.80 Co 0.15 Al 0.05 One or more of O2, LiFePO4, LiMnPO4 and their respective modified materials.

[0130] Lithium-ion battery cells undergo lithium intercalation and deintercalation during the charge and discharge process, resulting in different molar contents of lithium in different discharge states. The molar contents of lithium in the positive electrode active materials listed in this disclosure refer to the initial state of the material, i.e., the state before the materials are added. The molar contents of lithium in the positive electrode active materials used in lithium-ion battery cells will change after charge and discharge cycles. The molar contents of oxygen in the positive electrode active materials listed in this disclosure are only theoretical values. Lattice oxygen release can cause the molar content of oxygen to change, and the actual molar content of oxygen will also fluctuate.

[0131] The modified materials of the above-mentioned positive electrode active materials may be the positive electrode active materials subjected to doping modification and / or surface coating modification.

[0132] In some embodiments, the positive electrode film layer may further include a positive electrode binder, which may include but is not limited to one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin.

[0133] In some embodiments, the positive electrode film layer may further include a positive electrode conductive agent, which may include but is not limited to one or more of superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, carbon nanofibers, and vapor grown carbon fibers (VGCF).

[0134] In some embodiments, the positive electrode current collector may be a metal foil or a composite current collector. As examples of metal foils, carbon-coated aluminum foil, aluminum foil, nickel foil, and titanium foil may be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. As an example, the metal material may include, but is not limited to, one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. As an example, the polymer material base layer may include, but is not limited to, one or more of polypropylene, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene.

[0135] The positive electrode film is typically formed by coating a positive electrode slurry onto a positive electrode current collector, drying it, and cold pressing it. The positive electrode slurry is typically formed by dispersing the positive electrode active material, positive electrode conductive agent, positive electrode binder, and any other components in a solvent and stirring them uniformly. The solvent can be, but is not limited to, N-methylpyrrolidone (NMP).

[0136] [Isolator]

[0137] The separator can be a separate component located between the positive electrode sheet and the negative electrode sheet, or it can be attached to the surface of the positive electrode sheet or the negative electrode sheet.

[0138] In some embodiments, the separator may be a separator. The present disclosure has no particular limitation on the type of separator, and any known separator with a porous structure having good chemical stability and mechanical stability may be selected.

[0139] As an example, the primary material of the separator can be selected from at least one of glass fiber, non-woven fabric, polyethylene, polypropylene, polyvinylidene fluoride, and ceramic. The separator can be a single-layer film or a multi-layer composite film, without particular limitation. When the separator is a multi-layer composite film, the materials of each layer can be the same or different, without particular limitation.

[0140] Optionally, an inorganic particle coating, an organic particle coating or an organic / inorganic composite coating may be coated on the surface of the isolation membrane.

[0141] In some embodiments, the separator may be a solid electrolyte sheet comprising a solid electrolyte material. Alternatively, the solid electrolyte material may comprise one or more of a sulfide solid electrolyte material, a halide solid electrolyte material, an oxide solid electrolyte material, and a polymer solid electrolyte material. The types of sulfide solid electrolyte materials, halide solid electrolyte materials, oxide solid electrolyte materials, and polymer solid electrolyte materials can be found above and are not further described here.

[0142] In some embodiments, the solid electrolyte sheet may further include a binder or may not include a binder, which can be adjusted according to the preparation process of the battery cell. Optionally, the binder may include, but is not limited to, polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, fluorinated acrylate resin, styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, methyl vinyl silicone rubber, nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), thermoplastic styrene-butadiene rubber (SBS), isoprene rubber, butadiene rubber (BR), ethyl cellulose, fluororubber, and one or more of acrylate rubber.

[0143] In some embodiments, the lithium-ion battery cell includes an electrolyte, which includes an electrolyte salt and an organic solvent. Optionally, the electrolyte salt may include, but is not limited to, one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalatoborate (LiDFOB), lithium dioxalatoborate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorobis(oxalatophosphate) (LiDFOP), and lithium tetrafluorooxalatophosphate (LiTFOP). Alternatively, the organic solvent may include, but is not limited to, one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0144] In some embodiments, the electrolyte may further include additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, or additives that can improve certain properties of the secondary battery cells, such as additives that improve overcharge performance, additives that improve high-temperature performance, and additives that improve low-temperature performance.

[0145] The preparation method of lithium-ion battery cells is well known. In some embodiments, a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte can be assembled to form a battery cell. As an example, the positive electrode sheet, separator, and negative electrode sheet can be assembled to form an electrode assembly. The electrode assembly is then placed in an outer packaging, dried, and then injected with electrolyte. After packaging and resting, a lithium-ion battery cell is obtained.

[0146] Example

[0147] The following examples describe the present disclosure in more detail. These examples are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by mass, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0148] Example 1

[0149] Preparation of silicon-based materials

[0150] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0151] The silicon-carbon material intermediate and water were placed in a sealed environment at a mass ratio of 100:15, and a passivation reaction was carried out at 120°C for 6 hours to obtain a silicon-based material. D / I G It is 0.78.

[0152] Preparation of negative electrode sheet

[0153] The above-prepared silicon-based material, negative electrode conductive agent carbon nanotubes (CNTs), and negative electrode binder polyacrylic acid (PAA) are mixed in a mass ratio of 8:1:1, and then deionized water is added and stirred to form a uniform negative electrode slurry; the negative electrode slurry is evenly coated on one surface of the copper foil current collector, and then dried and cold pressed to obtain a negative electrode sheet.

[0154] Preparation of positive electrode

[0155] The positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O2, positive electrode conductive agent conductive carbon black, and positive electrode binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 8:1:1, and then N-methylpyrrolidone is added and stirred to form a uniform positive electrode slurry; the positive electrode slurry is evenly coated on one surface of the aluminum foil current collector, and then dried and cold pressed to obtain the positive electrode sheet.

[0156] Preparation of isolation membrane

[0157] A commercially available polyethylene porous polymer film was used as the separator.

[0158] Preparation of electrolyte

[0159] Ethylene carbonate (EC) and dimethyl carbonate (DMC) were mixed in a volume ratio of 1:1 to form an organic solvent, and then lithium hexafluorophosphate LiPF6 was added to prepare an electrolyte with a concentration of 1 mol / L.

[0160] Preparation of lithium-ion battery cells

[0161] The positive electrode sheet, separator, and negative electrode sheet prepared above are stacked in sequence so that the separator is located between the positive and negative electrode sheets; the stacked positive electrode sheet, separator, and negative electrode sheet are placed in an aluminum-plastic bag, and after high-temperature drying, the electrolyte is injected according to the injection coefficient of 3g / Ah; then vacuum packaging, standing, and other processes are carried out to obtain a lithium-ion battery cell.

[0162] Example 2

[0163] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0164] Preparation of silicon-based materials

[0165] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0166] The silicon-carbon material intermediate and water were placed in a sealed environment at a mass ratio of 100:15, and a passivation reaction was carried out at 120°C for 12 hours to obtain a silicon-based material. D / I G It is 0.78.

[0167] Example 3

[0168] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0169] Preparation of silicon-based materials

[0170] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0171] The silicon-carbon material intermediate and water were placed in a sealed environment at a mass ratio of 100:15, and a passivation reaction was carried out at 200°C for 12 hours to obtain a silicon-based material. D / I G It is 0.78.

[0172] Example 4

[0173] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0174] Preparation of silicon-based materials

[0175] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0176] The silicon-carbon material intermediate and water were placed in a sealed environment at a mass ratio of 100:23, and a passivation reaction was carried out at 160°C for 4 hours to obtain a silicon-based material. D / I G It is 0.77.

[0177] Example 5

[0178] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0179] Preparation of silicon-based materials

[0180] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The mass content of O element and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si element and C element is 1, that is, Si / C is 1.

[0181] The silicon-carbon material intermediate and water are placed in a closed environment at a mass ratio of 100:23, and a passivation reaction is carried out at 220°C for 24h to obtain a silicon-based material. The I D / I G The mass content of O element and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si element and C element is 1, that is, Si / C is 1.

[0182] Example 6

[0183] The preparation method of the lithium ion battery monomer is the same as that in Example 1, except for the following differences.

[0184] Preparation of silicon-based materials

[0185] The coconut shell porous carbon substrate is placed in a fluidized bed device, a mixed gas of silane gas and nitrogen gas is introduced into the device, and amorphous silicon nanoparticles are formed by cracking of silane and deposited in the pores of the porous carbon substrate at 450°C to obtain a silicon-carbon material intermediate. The I D / I G The mass content of O element and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si element and C element is 1, that is, Si / C is 1.

[0186] The silicon-carbon material intermediate and water are placed in a closed environment at a mass ratio of 100:25, and a passivation reaction is carried out at 180°C for 18h to obtain a silicon-based material. The I D / I G The mass content of O element and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si element and C element is 1, that is, Si / C is 1.

[0187] Example 7

[0188] The preparation method of the lithium ion battery monomer is the same as that in Example 1, except for the following differences.

[0189] Preparation of silicon-based materials

[0190] The coconut shell porous carbon substrate is placed in a fluidized bed device, a mixed gas of silane gas and nitrogen gas is introduced into the device, and amorphous silicon nanoparticles are formed by cracking of silane and deposited in the pores of the porous carbon substrate at 450°C to obtain a silicon-carbon material intermediate. The I D / I G The mass content of O element and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si element and C element is 1, that is, Si / C is 1.

[0191] The silicon-carbon material intermediate and water were placed in a sealed environment at a mass ratio of 100:27, and a passivation reaction was carried out at 160°C for 10 hours to obtain a silicon-based material. D / I G It is 0.78.

[0192] Example 8

[0193] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0194] Preparation of silicon-based materials

[0195] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0196] The silicon-carbon material intermediate and water were placed in a sealed environment at a mass ratio of 100:30, and a passivation reaction was carried out at 180°C for 16 hours to obtain a silicon-based material. D / I G It is 0.76.

[0197] Example 9

[0198] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0199] Preparation of silicon-based materials

[0200] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0201] The silicon-carbon material intermediate and water were placed in a sealed environment at a mass ratio of 100:35, and a passivation reaction was carried out at 140°C for 2 hours to obtain a silicon-based material. D / I G It is 0.76.

[0202] Example 10

[0203] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0204] Preparation of silicon-based materials

[0205] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of the O element and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of the Si element and the C element is 1, that is, Si / C is 1.

[0206] The silicon-carbon material intermediate and water are placed in a sealed environment at a mass ratio of 100:40, and a passivation reaction is carried out at 300°C for 2 hours to obtain a silicon-based material. D / I G It is 0.76.

[0207] Example 11

[0208] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0209] Preparation of silicon-based materials

[0210] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0211] The silicon-carbon material intermediate and water are placed in a sealed environment at a mass ratio of 100:3, and a passivation reaction is carried out at 80°C for 48 hours to obtain a silicon-based material. D / I G It is 0.77.

[0212] Example 12

[0213] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0214] Preparation of silicon-based materials

[0215] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0216] The silicon-carbon material intermediate and water were placed in a sealed environment at a mass ratio of 100:60, and a passivation reaction was carried out at 300°C for 0.5 h to obtain a silicon-based material. D / I G It is 0.79.

[0217] Comparative Example 1

[0218] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0219] Preparation of silicon-based materials

[0220] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-based material. D / I G The sum of the mass contents of O and other impurity elements in the silicon-based material is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0221] Comparative Example 2

[0222] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0223] Preparation of silicon-based materials

[0224] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0225] The silicon-carbon material intermediate was placed in a tube furnace and passed through a mixture of nitrogen and air with a volume ratio of 99:1 at 600°C for 20 minutes to obtain a silicon-based material. D / I G is 1.4.

[0226] Comparative Example 3

[0227] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0228] Preparation of silicon-based materials

[0229] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0230] The silicon-carbon material intermediate was added to water at a mass ratio of 1:20, and then transferred to a hydrothermal reactor and sealed and heated at 200°C for 10 hours to obtain a silicon-based material. D / I G It is 0.78.

[0231] Comparative Example 4

[0232] The preparation method of the lithium-ion battery cell is the same as that of Example 1 except for the following differences.

[0233] Preparation of silicon-based materials

[0234] The coconut shell porous carbon matrix is ​​placed in a fluidized bed device, and a mixture of monosilane gas and nitrogen is introduced into the device. At 450°C, the monosilane is cracked to form amorphous silicon nanoparticles that are deposited in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate. D / I G The sum of the mass contents of O and other impurity elements in the silicon-carbon material intermediate is less than 1%, and the mass multiple of Si and C is 1, that is, Si / C is 1.

[0235] The silicon-carbon material intermediate and water are placed in a sealed environment at a mass ratio of 100:35, and a passivation reaction is carried out at 600°C for 1 hour to obtain a silicon-based material. D / IG It is 0.77.

[0236] Performance testing of silicon-based materials

[0237] (1) Powder resistivity test of silicon-based materials

[0238] The determination method refers to GB / T 30835-2014, and the test instrument is ST2722 powder resistivity tester.

[0239] On a powder resistivity tester, 2.4 g of silicon-based material powder was placed in a feeding cup, a pressure of 5 MPa was applied, and the powder resistivity of the silicon-based material under 5 MPa was recorded.

[0240] On a powder resistivity tester, 2.4 g of silicon-based material powder was placed in a feeding cup, a pressure of 50 MPa was applied, and the powder resistivity of the silicon-based material under 50 MPa was recorded.

[0241] (2) Specific surface area test of silicon-based materials

[0242] The specific surface area of ​​silicon-based materials was determined according to GB / T 19587-2017 using nitrogen adsorption surface area analysis and calculation using the Brunauer-Emmett-Teller (BET) method. The test instrument was a Micromeritics Tri-Star 3020 surface area pore size analyzer.

[0243] Table 1

[0244]

[0245] The silicon-based material prepared in Comparative Example 1 was not subjected to passivation treatment, and the silicon-based materials of Examples 1 to 12 and Comparative Examples 2 to 4 were obtained by passivating the silicon-based material prepared in Comparative Example 1.

[0246] It can be seen from the test results in Table 1 that, compared with the silicon-based material prepared in Comparative Example 1, the silicon-based material prepared in the present disclosure has lower powder resistivity and smaller specific surface area.

[0247] Figure 3 The Raman spectra of the silicon-based materials prepared in Example 1 and Comparative Example 1 are shown. Figure 3 It can be seen that the silicon-based material prepared by the preparation method disclosed in the present invention has basically no effect on the properties of the porous carbon matrix.

[0248] Figure 4 The X-ray photoelectron spectroscopy (XPS) diagrams of the silicon-based materials prepared in Example 1 and Comparative Example 1 are shown. Figure 4It can be seen that the Si-Si bonds on the surface of the silicon-based material prepared in the present disclosure disappear, and only Si-O bonds exist. Therefore, it is believed that the surface of the silicon nanoparticles is completely passivated into a silicon oxide passivation layer.

[0249] Figure 5 The X-ray diffraction (XRD) patterns of the silicon-based materials prepared in Example 1 and Comparative Example 1 are shown. Figure 5 It can be seen that the silicon-based material prepared by the present disclosure can effectively reduce the Si peak intensity. On the one hand, the conversion of Si to Si-O reduces the expansion degree of the silicon nanoparticles themselves. On the other hand, the Si-O type passivation layer can effectively alleviate the particle pulverization problem caused by the volume expansion of silicon nanoparticles Li-Si alloying, thereby alleviating the volume expansion of the negative electrode and lithium-ion battery monomer.

[0250] Thermal stability test of negative electrode

[0251] (1) Thermogravimetric testing

[0252] Under a 25°C environment, the lithium-ion battery cell was charged at a constant current rate of 0.33C to 4.3V, and then charged at a constant voltage until the current decayed to 0.05C. The negative electrode plate (i.e., the fully charged negative electrode plate) was then disassembled for thermogravimetric testing.

[0253] The test conditions are: O2 atmosphere, heating rate 10°C / min, 25°C to 600°C.

[0254] (2) Differential scanning calorimetry test

[0255] Under a 25°C environment, the lithium-ion battery cell was charged at a constant current rate of 0.33C to 4.3V, and then charged at a constant voltage until the current decayed to 0.05C. The negative electrode plate (i.e., the fully charged negative electrode plate) was then disassembled for differential scanning calorimetry testing.

[0256] The test standard refers to GB / T 13464-2008.

[0257] The test process is as follows: Sample preparation: In an argon-protected glove box, punch out a small disc with a diameter of 5 mm from the middle of the fully filled negative electrode piece, place it in a crucible, flatten it, and seal it; parameter setting: nitrogen atmosphere, purge gas 60 mL / min, protective gas 20 mL / min; temperature rise program: heating rate 10℃ / min, 35℃ to 460℃.

[0258] Figure 6 Thermogravimetric analysis (TG) graphs of the fully charged negative electrode sheets of Example 1 and Comparative Example 1 are shown. Figure 7 The differential scanning calorimetry (DSC) diagrams of the fully charged negative electrode sheets of Example 1 and Comparative Example 1 are shown. Figure 6 and Figure 7It can be seen that the heat generation of the full negative electrode sheet prepared from the silicon-based material of the present disclosure is reduced by about 20%, and the thermal stability temperature is increased by about 80℃.

[0259] Performance testing of lithium-ion battery cells

[0260] (1) Thermal runaway gas production test

[0261] At 25℃, the lithium ion battery monomer was charged to 4.3V at a constant current of 0.33C, then the lithium ion battery monomer was placed in a sealed container and heated to smoke and fire, the temperature of the lithium ion battery monomer was monitored during the thermal runaway process, and the total gas production was calculated by the pressure change of the sealed container, and the gas component was analyzed by chromatography.

[0262] (2) Rate performance test

[0263] At 25℃, the lithium ion battery monomer was charged to 4.3V at a constant current of 0.5C, then charged to a constant voltage until the current decayed to 0.05C, then discharged to 2.8V at a constant current of 0.5C, and then cycled for 5 cycles according to the above steps to obtain the discharge capacity of the lithium ion battery monomer at a rate of 0.5C;

[0264] Then the lithium ion battery monomer was charged to 4.3V at a constant current of 1C, then charged to a constant voltage until the current decayed to 0.05C, then discharged to 2.8V at a constant current of 1C, and then cycled for 5 cycles according to the above steps to obtain the discharge capacity of the lithium ion battery monomer at a rate of 1C;

[0265] Then the lithium ion battery monomer was charged to 4.3V at a constant current of 1.5C, then charged to a constant voltage until the current decayed to 0.05C, then discharged to 2.8V at a constant current of 1.5C, and then cycled for 5 cycles according to the above steps to obtain the discharge capacity of the lithium ion battery monomer at a rate of 1.5C;

[0266] Then the lithium ion battery monomer was charged to 4.3V at a constant current of 2C, then charged to a constant voltage until the current decayed to 0.05C, then discharged to 2.8V at a constant current of 2C, and then cycled for 5 cycles according to the above steps to obtain the discharge capacity of the lithium ion battery monomer at a rate of 2C;

[0267] Then the lithium ion battery monomer was charged to 4.3V at a constant current of 3C, then charged to a constant voltage until the current decayed to 0.05C, then discharged to 2.8V at a constant current of 3C, and then cycled for 5 cycles according to the above steps to obtain the discharge capacity of the lithium ion battery monomer at a rate of 3C.

[0268] (3) Normal temperature cycle performance test

[0269] The lithium ion battery cell was charged at a rate of 0.33C to 4.3V at 25°C, then charged at a constant voltage until the current decayed to 0.05C; then discharged at a rate of 0.5C to a voltage of 2.8V to obtain the first cycle discharge capacity; then the cycle charging and discharging was carried out according to the above steps, and the cycle number experienced when the discharge capacity of the lithium ion battery cell decayed to 80% of the first cycle discharge capacity was recorded.

[0270] (4) High temperature cycle performance test

[0271] The lithium ion battery cell was charged at a rate of 0.33C to 4.3V at 45°C, then charged at a constant voltage until the current decayed to 0.05C; then discharged at a rate of 0.5C to a voltage of 2.8V to obtain the first cycle discharge capacity; then the cycle charging and discharging was carried out according to the above steps. The cycle number experienced when the discharge capacity of the lithium ion battery cell decayed to 80% of the first cycle discharge capacity was recorded.

[0272] Figure 8 The thermal runaway gas production graph of the lithium ion battery cell prepared in Example 1 and Comparative Example 1 is shown. The total gas production of the lithium ion battery cell prepared in Comparative Example 1 is 0.095 L / Ah, and the total gas production of the lithium ion battery cell prepared in the present disclosure is 0.055 L / Ah, which is about 40% lower than that of Comparative Example 1.

[0273] Figure 9 The discharge capacity graph of the lithium ion battery cell prepared in Example 1 at different rates is shown. Figure 10 The discharge capacity graph of the lithium ion battery cell prepared in Comparative Example 1 at different rates is shown. From the above Figure 9 and Figure 10 It can be seen that the silicon-based material prepared in the present disclosure can make the lithium ion battery cell have better rate performance.

[0274] Table 2

[0275]

[0276] From the test results in Table 2, it can be seen that the present disclosure uses water with a mass fraction of 3%-60% as a transformation agent compared with the silicon-carbon material intermediate, and performs passivation treatment on the silicon nanoparticles at a low temperature of 80°C-300°C, which does not affect the intrinsic performance of the silicon-carbon material intermediate, and can form a silicon oxide passivation layer in situ on the surface of the silicon nanoparticles, also can improve the electronic conductivity of the silicon-carbon material intermediate, reduce the specific surface area of the silicon-carbon material intermediate, thereby reducing the electrolyte side reaction, also can alleviate the negative electrode pulverization problem caused by the volume expansion of the silicon nanoparticles, so that the lithium ion battery cell using the silicon-based material has high thermal safety performance, good cycle performance and good rate performance.

[0277] Comparative Example 2 uses air to perform passivation treatment under high temperature environment. The I of silicon-carbon material intermediate before passivation treatment is D / I G is 0.76, and the I of the silicon-based material prepared after passivation treatment D / I G It is 1.40, which indicates that the high-temperature passivation treatment in an air atmosphere affects the performance of the porous carbon matrix itself, and the graphitization degree of the porous carbon matrix itself changes; at the same time, the mass content of the C element in the silicon-based material prepared in Comparative Example 2 is much smaller than the mass content of the Si element, indicating that the high-temperature passivation treatment in an air atmosphere will also cause the porous carbon matrix to be partially oxidized, so that the pore structure of the porous carbon matrix cannot be well maintained, thereby affecting the cyclic stability of the prepared silicon-based material.

[0278] Comparative Example 3 uses a severe excess of water for hydrothermal passivation treatment, which will cause the silicon nanoparticles in the porous carbon matrix to be completely converted into silicon oxide, thereby changing the intrinsic properties of the silicon-carbon material. In addition, the powder resistivity of the silicon-based material prepared by the hydrothermal passivation treatment is high, and the lithium ion transmission performance of the silicon-based material is deteriorated, resulting in poor cycle performance of the lithium-ion battery cell.

[0279] Comparative Example 4 uses water as a conversion agent, but the passivation treatment is performed at high temperature. Compared to passivation treatment at low temperature, the cycling performance of the lithium-ion battery cell in Comparative Example 4 is significantly worse. On the one hand, the high-temperature passivation treatment changes the crystalline morphology of the silicon nanoparticles, converting them from amorphous silicon (i.e., non-crystalline silicon) to crystalline silicon, resulting in a significant loss in the cycling capacity retention of the lithium-ion battery cell. On the other hand, the high-temperature passivation treatment also causes a small amount of oxidation of the porous carbon matrix, which prevents the pore structure of the porous carbon matrix from being well maintained.

[0280] It should be noted that the present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and within the scope of the technical solution of the present disclosure, embodiments having substantially the same structure as the technical concept and exerting the same effects are all included in the technical scope of the present disclosure. In addition, within the scope of the present disclosure, various modifications that can be conceived by those skilled in the art to the embodiments, and other methods constructed by combining some of the constituent elements of the embodiments are also included in the scope of the present disclosure.

Claims

1. A silicon-based material, characterized in that: The silicon-based material comprises a porous carbon matrix and silicon nanoparticles located in the pores of the porous carbon matrix, wherein the surface of the silicon nanoparticles has a silicon oxide passivation layer formed by a passivation reaction. D / I G I of the porous carbon matrix before the passivation reaction D / I G The ratio is (0.95-1.05):1,I D Indicates that the Raman spectrum is at 1350±50cm -1 The D peak intensity at I G Indicates that the Raman spectrum is at 1580±50cm -1 the mass multiple of Si element and C element in the silicon-based material is recorded as A, the mass multiple of Si element and C element before the passivation reaction is recorded as B, A: B is (0.95-1.05):

1.

2. The silicon-based material according to claim 1, characterized in that The mass content of O element in the silicon-based material is 2%-34%.

3. The silicon-based material according to any one of claims 1 to 2, characterized in that: The mass content of Si element in the silicon-based material is 25%-60%; and / or, The mass content of the C element in the silicon-based material is 20%-60%.

4. The silicon-based material according to any one of claims 1 to 3, characterized in that: The thickness of the silicon oxide passivation layer is less than or equal to 0.4 times the particle size of the silicon nanoparticles having the silicon oxide passivation layer on the surface.

5. The silicon-based material according to any one of claims 1 to 4, characterized in that: The particle size of the silicon nanoparticles with a silicon oxide passivation layer on the surface is 0.4 nm-45 nm.

6. The silicon-based material according to any one of claims 1 to 5, characterized in that: The pore size of the porous carbon matrix is ​​0.5 nm to 50 nm; and / or, The specific surface area of ​​the porous carbon matrix is ​​200 m 2 / g-3000m 2 / g.

7. The silicon-based material according to any one of claims 1 to 6, characterized in that: The volume distribution particle size Dv50 of the silicon-based material is 0.8 μm-20 μm; and / or, The specific surface area of ​​the silicon-based material is 0.5 m 2 / g-4m 2 / g.

8. A method for preparing a silicon-based material, comprising the following steps: providing a porous carbon matrix; depositing silicon nanoparticles in the pores of the porous carbon matrix by vapor deposition to obtain a silicon-carbon material intermediate; subjecting the obtained silicon-carbon material intermediate to a passivation reaction with water in a closed environment and forming a silicon oxide passivation layer on the surface of the silicon nanoparticles to obtain a silicon-based material, wherein the temperature of the passivation reaction is 80°C-300°C, and the mass of the water is 3%-60% of the mass of the silicon-carbon material intermediate.

9. The preparation method according to claim 8, characterized in that The temperature of the passivation reaction is 120°C-220°C; and / or, The mass of the water is 15%-40% of the mass of the silicon-carbon material intermediate.

10. The preparation method according to any one of claims 8 to 9, characterized in that: The passivation reaction time is 0.5h-48h.

11. The preparation method according to any one of claims 8 to 10, characterized in that: The passivation reaction time is 2h-24h.

12. The preparation method according to any one of claims 8 to 11, characterized in that: The pore size of the porous carbon matrix is ​​0.5 nm to 50 nm; and / or, The specific surface area of ​​the porous carbon matrix is ​​200 m 2 / g-3000m 2 / g; and / or, The particle size of the silicon nanoparticles is 0.4 nm-40 nm.

13. The preparation method according to any one of claims 8 to 12, characterized in that: The step of depositing silicon nanoparticles in the pores of the porous carbon matrix by vapor deposition to obtain a silicon-carbon material intermediate includes the following steps: decomposing silane gas by chemical vapor deposition to deposit silicon nanoparticles in the pores of the porous carbon matrix to obtain a silicon-carbon material intermediate.

14. The preparation method according to claim 13, characterized in that The temperature of the vapor deposition is 400° C.-800° C.; and / or, The silane gas includes one or more of monosilane, disilane, dichlorosilane, trichlorosilane, tetrafluorosilane, hexamethyldisilane, methylvinyldichlorosilane, dimethylvinylchlorosilane, vinyltrichlorosilane, and tris(trimethylsilyl)silane.

15. A lithium-ion battery cell, comprising a positive electrode sheet, a negative electrode sheet, and a separator, wherein the separator is located between the positive electrode sheet and the negative electrode sheet, characterized in that: The negative electrode plate comprises the silicon-based material according to any one of claims 1 to 7 or the silicon-based material prepared by the preparation method according to any one of claims 8 to 14.

16. A battery device, characterized in that: The invention comprises a plurality of lithium-ion battery cells as claimed in claim 15 .

17. An electrical device, characterized in that: The invention comprises the lithium-ion battery cell according to claim 15 or the battery device according to claim 16.

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