Silicon negative electrode material, preparation method thereof and lithium ion battery

Abstract

The invention relates to the technical field of batteries, in particular to a silicon negative electrode material, a preparation method thereof and a lithium ion battery. The invention provides a silicon negative electrode material. The silicon negative electrode material comprises a Si inner core and a Li4SiO4 shell layer coated on the surface of the Si inner core, in an XPS spectrogram of the silicon negative electrode material, the peak area of the Si-OH bond accounts for 0-8% of the sum of the peak area of the Si-OH bond and the peak area of the Si-Si bond. The silicon negative electrode material does not contain Si-OH groups or contains less Si-OH groups, has excellent structural stability and chemical reaction inertness, can provide a transmission path for migration of Li < + >, has high initial coulombic efficiency, and also inhibits volume expansion of the silicon negative electrode material.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and particularly to a silicon negative electrode material, a preparation method thereof, and a lithium ion battery. Background Art

[0002] As a clean energy source, lithium ion batteries play an irreplaceable role in the fields of energy storage, electric vehicles, 3C products, etc. Regarding their negative electrodes, silicon materials have a theoretical specific capacity (4200 mAh / g) much higher than that of current commercial graphite (372 mAh / g), and have advantages such as a lower lithium deintercalation potential, rich content and easy availability, as well as environmental friendliness and low cost. They show high industrial application prospects and are ideal lithium ion battery negative electrode materials. However, the methods reported so far, such as chemical vapor deposition and vacuum condensation, for preparing high-purity and controllable particle size nano-silicon powder have high costs and are not suitable for large-scale production. Wet grinding of silicon using a sand mill has advantages such as high efficiency and environmental friendliness, and conforms to the concept of green production. This method for grinding and preparing nano-silicon powder is simple in operation, low in cost, controllable in particle size, and easy to realize industrial production.

[0003] Wet grinding of micron-sized silicon powder using an industrial sand mill can significantly reduce the particle size, which can be refined to below 100 nm. However, after preparing a silicon battery, the initial efficiency is relatively low (usually about 80%, much lower than that of a graphite negative electrode). Summary of the Invention

[0004] After in-depth research on the prior art, the inventors of the present invention surprisingly found that the main reason for the low initial Coulomb efficiency is that during the wet ball milling of silicon powder, a shell layer containing SiO and OH functional groups will form on the surface of the refined silicon under the action of anhydrous ethanol or ethanol-containing grinding solvents. This shell layer structure will generate Li-containing compounds, such as Li2O and Li4SiO4 inactive inert products, during the lithium intercalation process, resulting in the inactivation of some Li + being unable to deintercalate and lose its activity.

[0005] The Si-OH functional groups on the surface of the silicon-based negative electrode can be divided into three categories: free Si-OH groups, geminal Si-OH groups, and associated Si-OH groups. Among them, the associated Si-OH groups are connected by hydrogen bonds and do not have chemical activity. Moreover, the -OH groups of anhydrous ethanol will also form hydrogen bonds with Si-OH. Therefore, such Si-OH groups will still not react with the modifier during the grinding process and then transform into an inert stable phase, affecting the initial Coulomb efficiency.

[0006] In view of this, this invention is specifically proposed.

[0007] The first object of the present invention is to provide a silicon negative electrode material with excellent structural stability, chemical reaction inertness, high initial Coulomb efficiency, and low expansion rate.

[0008] The second object of the present invention is to provide a preparation method of a silicon negative electrode material, which improves the initial Coulomb efficiency of the silicon negative electrode material and suppresses volume expansion.

[0009] The third object of the present invention is to provide a lithium-ion battery with excellent electrochemical performance.

[0010] In order to achieve the above objects of the present invention, the following technical solutions are specifically adopted:

[0011] In a first aspect, the present invention provides a silicon negative electrode material, including: a Si core and a Li4SiO4 shell layer coated on the surface of the Si core;

[0012] In the XPS spectrum of the silicon negative electrode material, the peak area of the Si-OH bond accounts for 0% to 8% of the sum of the peak areas of the Si-OH bond and the Si-Si bond.

[0013] Further, in the XPS spectrum of the silicon negative electrode material, the peak area of the Si-OH bond accounts for 0% to 5.5% of the sum of the peak areas of the Si-OH bond and the Si-Si bond.

[0014] Further, the thickness of the Li4SiO4 shell layer is 10 to 50 nm;

[0015] And / or, the particle size of the silicon negative electrode material is 1 to 100 μm.

[0016] In a second aspect, the present invention also provides a preparation method of the silicon negative electrode material as described above, including the following steps:

[0017] After first grinding the micron-sized silicon powder and the abrasive, a mixture is obtained; after second grinding the mixture, an acidic solution containing H + and a lithium compound modifier, a slurry is obtained; after drying the slurry, the silicon negative electrode material is obtained;

[0018] Or,

[0019] After third heat grinding the micron-sized silicon powder and the abrasive, a mixture is obtained; after fourth grinding the mixture and the lithium compound modifier, a slurry is obtained; after drying the slurry, the silicon negative electrode material is obtained.

[0020] Further, the abrasive includes ethanol;

[0021] And / or, the mass ratio of the micron-sized silicon powder to the abrasive is 1:(1 to 10).

[0022] Further, the rotation speed of the first grinding is 1800 to 3000 r / min, the time is 1 to 5 h, and the diameter of the grinding zirconia balls is 1 to 3 mm.

[0023] Further, the temperature of the third heat grinding is 50-90°C, the rotation speed is 1800-3000 r / min, the time is 1-5 h, and the diameter of the grinding zirconia balls is 1-3 mm.

[0024] Further, the acidic solution containing H + includes at least one of HCl, H2SO4, HNO3, and CH3COOH;

[0025] and / or, the molar ratio of H + in the acidic solution containing H + to the abrasive is 1:(10-100).

[0026] Further, the lithium compound modifier includes at least one of lithium carbonate, lithium oxide, and butyl lithium;

[0027] and / or, the molar ratio of H + in the acidic solution containing H + to Li + in the lithium compound modifier is (0.5-2):1.

[0028] Thirdly, the present invention also provides a lithium-ion battery, including the silicon negative electrode material as described above.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0030] 1. In the silicon negative electrode material of the present invention, there is no Si-OH group or the content is small, and it has excellent structural stability and chemical reaction inertness, which can provide a transmission path for the migration of Li + . In addition to having a high first Coulomb efficiency, it can also inhibit the volume expansion of the silicon negative electrode material.

[0031] 2. The preparation method of the silicon negative electrode material of the present invention weakens and eliminates the hydrogen bond action by increasing the H + concentration in the system or increasing the temperature, so that the adjacent two -OH groups of the Si-OH groups associated on the silicon surface are restored to activity and are eliminated in advance by reacting with the abrasive, and then a lithium compound modifier is added for modification, thereby forming a Li4SiO4 shell layer, making it have excellent structural stability and chemical reaction inertness, and providing a transmission path for the migration of Li + ; improving the first Coulomb efficiency and inhibiting the volume expansion of the silicon negative electrode material. Specific Embodiments

[0032] The technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments. However, those skilled in the art will understand that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For those reagents or instruments without indicating the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0033] A silicon negative electrode material, a preparation method thereof, and a lithium ion battery according to an embodiment of the present invention will be specifically described below.

[0034] In some embodiments of the present invention, a silicon negative electrode material is provided, including: a Si core and a Li4SiO4 shell layer coated on the surface of the Si core;

[0035] In the XPS spectrum of the silicon negative electrode material, the peak area of the Si-OH bond accounts for 0% to 8% of the sum of the peak areas of the Si-OH bond and the Si-Si bond.

[0036] The structure of the silicon negative electrode material of the present invention is a core-shell structure, the core is Si, and the shell layer is Li4SiO4 (lithium silicate); wherein, the Li4SiO4 shell layer serves as a passivation layer, similar to the prelithiation raw material, and its pre-formation can reduce the consumption of the electrolyte. At the same time, the conductivity of the Li4SiO4 phase is significantly higher than that of the pure silicon phase, which is also beneficial to improving the + migration rate at the negative electrode.

[0037] XPS is a surface test, and there are many Si-OH groups on the surface of micron-sized silicon powder (μ-Si). Such Si-OH groups will not react with the modifier during grinding and then transform into an inert stable phase, thus affecting the first Coulomb efficiency of the material; while there are no Si-OH groups or the content is small in the silicon negative electrode material of the present invention, which is beneficial to improving the performance of the material; the silicon negative electrode material has excellent structural stability and chemical reaction inertness, and can provide a transmission path for the migration of Li + In addition to having a high first Coulomb efficiency, it can also inhibit the volume expansion of the silicon negative electrode material.

[0038] The test method for the XPS spectrum of the silicon negative electrode material is as follows: Detect the Si species on the surface layer of the sample through an X-ray photoelectron spectrometer (XPS), and perform peak fitting on the Si 2p orbital through fitting software. The Si-Si peak located at ~100.4 eV, the Si-OH peak located at ~105.3 eV, and their corresponding peak areas can be obtained, and then the ratio of the peak area of the Si-OH bond to the sum of the peak areas of the Si-OH bond and the Si-Si bond can be calculated.

[0039] In the XPS spectrum of the silicon negative electrode material, the peak area of the Si-OH bond accounts for 0% to 8% of the sum of the peak areas of the Si-OH bond and the Si-Si bond; typically but not limited to, for example, in the XPS spectrum of the silicon negative electrode material, the peak area of the Si-OH bond accounts for 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8% of the sum of the peak areas of the Si-OH bond and the Si-Si bond, and any value between any two of them.

[0040] In some embodiments of the present invention, in the XPS spectrum of the silicon negative electrode material, the peak area of the Si-OH bond accounts for 0% to 5.5% of the sum of the peak areas of the Si-OH bond and the Si-Si bond.

[0041] In some embodiments of the present invention, the thickness of the Li4SiO4 shell layer is 10 to 50 nm; typically but not limited to, for example, the thickness of the Li4SiO4 shell layer can be 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, and any value between any two of them.

[0042] In some embodiments of the present invention, the particle size of the silicon negative electrode material is 1 to 100 μm; typically but not limited to, for example, the particle size of the silicon negative electrode material can be 1 μm, 10 μm, 20 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, and any value between any two of them; preferably 1 to 30 μm.

[0043] In some embodiments of the present invention, a preparation method of the above-mentioned silicon negative electrode material is further provided, including the following steps:

[0044] After first grinding the micron-sized silicon powder (μ-Si) and the abrasive, a mixture is obtained; after second grinding the mixture, an acidic solution containing H + and the lithium compound modifier, a slurry is obtained; after the slurry is dried, the silicon negative electrode material is obtained;

[0045] Or,

[0046] After the micron-sized silicon powder (μ-Si) and the abrasive are subjected to third heating and grinding, a mixture is obtained; after the mixture and the lithium compound modifier are subjected to fourth grinding, a slurry is obtained; after the slurry is dried, a silicon negative electrode material is obtained.

[0047] The associated Si-OH groups form hydrogen bonds due to the interaction between two adjacent hydroxyl groups (-OH) inevitably present on the silicon surface due to -O δ- and -H δ+ interaction, which makes both -OH lose activity and become inactive. Therefore, by increasing the H + concentration or increasing the temperature to weaken and eliminate the hydrogen bond interaction, the two -OH regain activity and are eliminated in advance through reaction with the abrasive (for example, the hydrogen bond interaction can be weakened and eliminated by increasing the H + concentration in the system or by heating, activating the associated Si-OH, and completely exposing the Si-OH groups on the Si surface); then a lithium compound modifier is added to modify the surface of μ-Si. The modifier uses a lithium compound, thereby forming a Li4SiO4 shell layer. Its advantages are as follows: one is its excellent structural stability and chemical reaction inertness, and the other is that its phase composition determines that this substance can provide a transmission path for the migration of Li + ; while using other compounds to form similar Na2SiO3 or Mn2SiO4, the former has poor conductivity, the latter will decompose, and Mn 2+ and Li + exchange consumes the electrolyte, which will instead reduce the initial efficiency. In addition, the preparation method of the silicon negative electrode material of the present invention can not only improve the initial Coulomb efficiency but also inhibit the volume expansion of the silicon negative electrode.

[0048] In some embodiments of the present invention, the particle size of the micron-sized silicon powder is 10 - 50 μm.

[0049] In some embodiments of the present invention, the abrasive includes ethanol.

[0050] In some embodiments of the present invention, the mass ratio of the micron-sized silicon powder to the abrasive is 1:(1 - 10); typically but not limitedly, for example, the mass ratio of the micron-sized silicon powder to the abrasive can be 1:1, 1:2, 1:4, 1:6, 1:8, 1:10 and any value between any two of them.

[0051] In some embodiments of the present invention, the rotational speed of the first grinding is 1800 - 3000 r / min, the time is 1 - 5 h, and the diameter of the grinding zirconia balls is 1 - 3 mm; typically but not restrictively, for example, the rotational speed of the first grinding can be 1800 r / min, 2000 r / min, 2200 r / min, 2400 r / min, 2600 r / min, 2800 r / min, 3000 r / min, and any value between any two of them; the time of the first grinding can be 1 h, 2 h, 3 h, 4 h, 5 h, and any value between any two of them; the diameter of the grinding zirconia balls for the first grinding can be 1 mm, 2 mm, 3 mm, and any value between any two of them; preferably, the temperature of the first grinding is room temperature (15 - 35 °C).

[0052] In some embodiments of the present invention, the temperature of the third heat grinding is 50 - 90 °C, the rotational speed is 1800 - 3000 r / min, the time is 1 - 5 h, and the diameter of the grinding zirconia balls is 1 - 3 mm; typically but not restrictively, for example, the temperature of the third heat grinding can be 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, and any value between any two of them; the rotational speed of the third heat grinding can be 1800 r / min, 2000 r / min, 2200 r / min, 2400 r / min, 2600 r / min, 2800 r / min, 3000 r / min, and any value between any two of them; the time of the third heat grinding can be 1 h, 2 h, 3 h, 4 h, 5 h, and any value between any two of them; the diameter of the grinding zirconia balls for the third heat grinding can be 1 mm, 2 mm, 3 mm, and any value between any two of them.

[0053] In some embodiments of the present invention, the acidic solution containing H + includes at least one of HCl, H2SO4, HNO3, and CH3COOH.

[0054] In some embodiments of the present invention, the molar ratio of H + in the acidic solution containing H + to the grinding agent is 1:(10 - 100); typically but not restrictively, for example, the molar ratio of H + in the acidic solution containing H + to the grinding agent can be 1:10, 1:20, 1:40, 1:60, 1:80, 1:100, and any value between any two of them.

[0055] In some embodiments of the present invention, the lithium compound modifier is soluble or slightly soluble in the grinding agent.

[0056] In some embodiments of the present invention, the lithium compound modifier includes at least one of lithium carbonate, lithium oxide, and butyllithium; the lithium compound modifier can in-situ convert the SiO bonds and OH functional groups formed on the surface of the micron-sized silicon powder into an inert and stable structure.

[0057] In some embodiments of the present invention, the lithium compound modifier includes at least one of lithium carbonate, lithium oxide, and butyllithium; alternatively, the lithium compound modifier includes an aqueous solution prepared from at least one of lithium carbonate, lithium oxide, and butyllithium.

[0058] In some embodiments of the present invention, the H + in the acidic solution containing H + and the Li + in the lithium compound modifier have a molar ratio of (0.5 - 2):1; typically but not restrictively, for example, the H + in the acidic solution containing H + and the Li + in the lithium compound modifier can have a molar ratio of 0.5:1, 1:1, 1.5:1, 2:1, and any value between any two of them.

[0059] Excessive lithium compounds will reduce the initial efficiency. The Si-OH that can react on the surface of the micron-sized silicon powder is limited. The lithium compound is only used to react with Si-OH. The excessive Li + will still remain in the solution and will remain on the surface of the silicon negative electrode material after drying. After being made into an electrode and assembled into a battery, these residual Li + will undergo deintercalation and provide capacity during the first discharge process, but will not return to the silicon negative electrode end during the charging process, thus ultimately resulting in a reduction in the initial efficiency.

[0060] In some embodiments of the present invention, when the acidic solution containing H + is not added in the preparation method of the silicon negative electrode material, the molar ratio of the abrasive to the lithium compound modifier is (25 - 50):1; typically but not restrictively, for example, the molar ratio of the abrasive to the lithium compound modifier can be 25:1, 30:1, 35:1, 40:1, 45:1, 50:1, and any value between any two of them.

[0061] In some embodiments of the present invention, the drying includes at least one of spray drying, centrifugal heating drying, stirring heating drying, drying in a blast drying oven, rotary evaporation, vacuum drying, and freeze drying; preferably, the drying temperature is 80 - 110°C. Drying can separate the material from the solvent.

[0062] In some embodiments of the present invention, a lithium ion battery is further provided, including the above-mentioned silicon negative electrode material.

[0063] Using the above silicon negative electrode material is beneficial to improving the initial charge-discharge capacity and the first Coulomb efficiency of the lithium-ion battery, and reducing the negative electrode expansion rate.

[0064] Example 1

[0065] The preparation method of the silicon negative electrode material provided in this example includes the following steps:

[0066] After grinding micron-sized silicon powder with a particle size of 30 μm and ethanol with a mass ratio of 100:100, the grinding speed is 2000 rpm, the time is 60 min, and the diameter of the grinding zirconia balls is 3 mm to obtain a mixture;

[0067] After grinding the mixture, HCl solution and lithium acetate, a slurry is obtained; wherein, the molar ratio of ethanol, HCl in the HCl solution and lithium acetate is 100:1:1;

[0068] After spray-drying the slurry at 110 °C, a silicon negative electrode material is obtained.

[0069] Example 2

[0070] The preparation method of the silicon negative electrode material provided in this example includes the following steps:

[0071] After grinding micron-sized silicon powder with a particle size of 30 μm and ethanol with a mass ratio of 50:50, the grinding speed is 2000 rpm, the time is 60 min, and the diameter of the grinding zirconia balls is 3 mm to obtain a mixture;

[0072] After grinding the mixture, HCl solution and lithium acetate, a slurry is obtained; wherein, the molar ratio of ethanol, HCl in the HCl solution and lithium acetate is 50:1:1;

[0073] After spray-drying the slurry at 110 °C, a silicon negative electrode material is obtained.

[0074] Example 3

[0075] The preparation method of the silicon negative electrode material provided in this example includes the following steps:

[0076] After grinding micron-sized silicon powder with a particle size of 20 μm and ethanol with a mass ratio of 25:25, the grinding speed is 1800 rpm, the time is 120 min, and the diameter of the grinding zirconia balls is 3 mm to obtain a mixture;

[0077] After grinding the mixture, HCl solution and lithium acetate, a slurry is obtained; wherein, the molar ratio of ethanol, HCl in the HCl solution and lithium acetate is 25:1:1;

[0078] After drying the slurry in a forced-air drying oven at 105 °C, a silicon negative electrode material is obtained.

[0079] Example 4

[0080] The preparation method of the silicon negative electrode material provided in this example includes the following steps:

[0081] After grinding micron-sized silicon powder with a particle size of 50 μm and ethanol with a mass ratio of 10:10, the grinding speed is 2700 rpm, the time is 120 min, and the diameter of the grinding zirconia balls is 2 mm to obtain a mixture;

[0082] After grinding the mixture, HCl solution and lithium acetate, a slurry is obtained; wherein, the molar ratio of ethanol, HCl in the HCl solution and lithium acetate is 10:1:1;

[0083] After drying the slurry in a forced-air drying oven at 90 °C, a silicon negative electrode material is obtained.

[0084] Example 5

[0085] The preparation method of the silicon negative electrode material provided in this example includes the following steps:

[0086] After grinding 10 μm micron-sized silicon powder and ethanol with a mass ratio of 10:10, the grinding temperature is 80 °C, the speed is 2500 rpm, the time is 90 min, and the diameter of the grinding zirconia balls is 1 mm to obtain a mixture;

[0087] After grinding the mixture and lithium acetate, a slurry is obtained; wherein, the molar ratio of ethanol and lithium acetate is 25:1;

[0088] After drying the slurry in a forced-air drying oven at 105 °C, a silicon negative electrode material is obtained.

[0089] Comparative Example 1

[0090] The silicon negative electrode material provided in this comparative example is micron-sized silicon powder.

[0091] Comparative Example 2

[0092] The preparation method of the silicon negative electrode material provided in this comparative example refers to Example 2 and does not add HCl solution.

[0093] Test Example

[0094] Perform XPS tests on the silicon negative electrode materials of Examples 1 to 5 and Comparative Examples 1 to 2 to obtain the XPS data of each silicon negative electrode material. Among them, the ratio of the peak area of the Si-OH bond to the sum of the peak areas of the Si-OH bond and the Si-Si bond is the proportion of the Si-OH bond; the ratio of the peak area of the Si-Si bond to the sum of the peak areas of the Si-OH bond and the Si-Si bond is the proportion of the Si-Si bond.

[0095] The XPS test method is as follows: Detect the Si species on the surface layer of the sample through an X-ray photoelectron spectrometer (XPS), and perform peak fitting on the Si 2p orbital through fitting software. The Si-Si peak located at ~100.4 eV, the Si-OH peak located at ~105.3 eV, and their corresponding peak areas can be obtained, and then the ratio of the peak area of the Si-OH bond to the sum of the peak areas of the Si-OH bond and the Si-Si bond can be calculated.

[0096] Assemble the silicon anode materials of Examples 1 to 5 and Comparative Examples 1 to 2 into half-cells respectively, and test their performance. The results are shown in Table 1.

[0097] Half-cell assembly: Silicon anode material: Conductive carbon black: PVDF = 8:1:1 (mass ratio), the separator is Celgard 2400, and the electrolyte is 1 M LiPF6 in EC:DEC = 1:1, 100 μL.

[0098] Test method for initial charge / discharge capacity: First, let it stand for 2 h; after standing, start the charge / discharge test, set the current density to 100 mA / g, and the charge / discharge cut-off voltage is 0 - 2 V. The initial charge / discharge capacity can be obtained after the test is completed.

[0099] Test method for initial Coulombic efficiency: After obtaining the initial charge / discharge capacity through the above steps, divide the initial charge capacity by the initial discharge capacity to obtain the initial Coulombic efficiency (for the positive electrode: discharge / charge, for the negative electrode: charge / discharge, and the test equipment directly calculates the data).

[0100] Test method for swelling rate: Send the tested negative electrode sheet for argon ion polishing and then observe the change in the height of the cross-section of the electrode sheet.

[0101] In Table 1, A:B is the mass ratio of micron-sized silicon powder and ethanol; B:C:D is the molar ratio of ethanol, HCl in the hydrochloric acid solution, and Li in lithium acetate. + of.

[0102] Table 1

[0103]

[0104] It can be seen from Table 1 that in the preparation method of the silicon anode material of the present invention, by adding an acidic solution containing H + or heating and grinding, the hydrogen bond interaction can be weakened and eliminated, which can make the reaction of the inert Si-OH groups affecting the first efficiency more complete, thereby being beneficial to improving the initial charge / discharge capacity and initial Coulombic efficiency of the silicon anode material and reducing the swelling rate.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A silicon negative electrode material, characterized in that: include: A Si core and a Li4SiO4 shell layer coated on the surface of the Si core; In the XPS spectrum of the silicon negative electrode material, the peak area of ​​the Si-OH bond accounts for 0% to 8% of the sum of the peak area of ​​the Si-OH bond and the peak area of ​​the Si-Si bond.

2. The silicon negative electrode material according to claim 1, characterized in that: In the XPS spectrum of the silicon negative electrode material, the peak area of ​​the Si-OH bond accounts for 0% to 5.5% of the sum of the peak area of ​​the Si-OH bond and the peak area of ​​the Si-Si bond.

3. The silicon negative electrode material according to claim 1, characterized in that: The thickness of the Li4SiO4 shell layer is 10 to 50 nm; And / or, the particle size of the silicon negative electrode material is 1 to 100 μm.

4. The method for preparing the silicon negative electrode material according to any one of claims 1 to 3, characterized in that: The following steps are involved: After first grinding the micron-sized silicon powder and the abrasive, a mixture is obtained; the mixture, the H + The acidic solution and the lithium compound modifier are subjected to a second grinding to obtain a slurry; the slurry is dried to obtain the silicon negative electrode material; or, The micron-sized silicon powder and the grinding agent are subjected to a third heating and grinding to obtain a mixture; the mixture and the lithium compound modifier are subjected to a fourth grinding to obtain a slurry; and the slurry is dried to obtain the silicon negative electrode material.

5. The method for preparing a silicon negative electrode material according to claim 4, characterized in that: The abrasive comprises ethanol; And / or, the mass ratio of the micron-sized silicon powder to the abrasive is 1:(1-10).

6. The method for preparing a silicon negative electrode material according to claim 4, characterized in that: The first grinding has a rotation speed of 1800-3000 r / min, a time of 1-5 hours, and a diameter of the grinding zirconium ball of 1-3 mm.

7. The method for preparing a silicon negative electrode material according to claim 4, characterized in that: The temperature of the third heating grinding is 50-90° C., the rotation speed is 1800-3000 r / min, the time is 1-5 hours, and the diameter of the grinding zirconium ball is 1-3 mm.

8. The method for preparing a silicon negative electrode material according to claim 4, characterized in that: The H + The acidic solution includes at least one of HCl, H2SO4, HNO3 and CH3COOH; And / or, the H + H in acidic solution + The molar ratio of the abrasive to the polishing agent is 1:(10-100).

9. The method for preparing a silicon negative electrode material according to claim 4, characterized in that: The lithium compound modifier includes at least one of lithium carbonate, lithium oxide and butyl lithium; And / or, the H-containing + H in acidic solution + and Li in the lithium compound modifier + The molar ratio is (0.5~2):

1.

10. A lithium ion battery, characterized in that: The invention comprises the silicon negative electrode material according to any one of claims 1 to 3.

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