Negative electrode active material and method for manufacturing the same, secondary battery and electrical device

Abstract

The present application provides a negative electrode active material, a method for manufacturing the same, a secondary battery, and an electric device. The silicon-carbon composite material is included, and the X-ray photoelectron spectroscopy (XPS) of the silicon-carbon composite material has an Si2p peak. After undergoing peak splitting processing, the Si2p peak can form the following sub-peaks, including a first sub-peak with a binding energy of 99.7 ± 0.2 eV and a second sub-peak with a binding energy of 98.9 ± 0.2 eV. The peak area ratio of the first sub-peak to the second sub-peak is 1 to 2:1.

Description

[Technical Field]

[0001] This application relates to the field of battery technology, and more particularly to negative electrode active materials and methods for producing the same, secondary batteries and electrical devices. [Background technology]

[0002] In recent years, the range of applications for secondary batteries has expanded considerably. They are widely used in energy storage systems such as hydroelectric, thermal, wind, and solar power plants, as well as in various fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. Due to the significant advancements in secondary batteries, there are increasingly higher demands regarding energy density, cycle performance, and safety performance.

[0003] Silicon-based anode materials are considered to be extremely promising next-generation high-energy-density lithium-ion battery anode materials due to their advantages such as high theoretical specific capacity, low lithium escape potential, environmental friendliness, abundant reserves, and low cost.

[0004] To further improve battery performance, conventional technology requires superior negative electrode active materials. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] In view of the above issues, this application provides a novel negative electrode active material, a method for manufacturing the same, a secondary battery, and an electrical device, which are described below. [Means for solving the problem]

[0006] In a first aspect, the present application provides a negative electrode active material comprising a silicon-carbon composite material, wherein X-ray photoelectron spectroscopy (XPS) of the silicon-carbon composite material has a Si2p spectrum, the Si2p spectrum has at least one characteristic peak, and the characteristic peak can form the following subpeaks after peak splitting: The first subpeak has a binding energy of 99.5-99.9 eV, and It includes a second subpeak with a binding energy of 98.7–99.1 eV, The peak area ratio between the first subpeak and the second subpeak is 1 to 2:1.

[0007] The anode active material of the above method has a high specific capacity and a long cycle life. It is important that the peak area ratio of the first subpeak to the second subpeak is 1 to 2:1. If the peak area ratio of the first subpeak to the second subpeak is less than 1, it indicates that the pure silicon content in the anode active material is high and the silicon crystal grains are large, which is unfavorable for the lifespan. If the peak area ratio of the first subpeak to the second subpeak exceeds 2, it indicates that the carbon content in the anode active material is too high, the specific capacity of the active material is low, and the initial effect is poor.

[0008] In some embodiments, the negative electrode active material is (1) The bond energy of the first subpeak corresponds to the bond energy of the Si-C bond, (2) The bond energy of the second subpeak corresponds to the bond energy of the Si-Si bond, (3) The first subpeak has a binding energy of 99.6-99.8 eV, for example, 99.7 eV. (4) The second subpeak has a binding energy of 98.8-99.0 eV, for example, 98.9 eV. (5) The peak area ratio of the first subpeak to the second subpeak is 1.5 to 2:1, for example 1.6 to 1.8:1, for example 1.7:1, and (6) A silicon-carbon composite material having one or more of the following characteristics: the silicon element content is 95 wt% to 99.9 wt% (e.g., 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, or 99.5 wt%) and the carbon element content is 0.1 wt% to 5 wt% (e.g., 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%).

[0009] In some embodiments, the negative electrode active material includes a matrix and the silicon-carbon composite material, and the silicon-carbon composite material is attached to the matrix.

[0010] In some embodiments, the matrix has a porous internal structure, and the silicon-carbon composite material is attached to the outer surface of the matrix and / or the voids of the porous internal structure.

[0011] In some embodiments, the material of the matrix includes one or more of a carbon material, a silicone material, a lithium titanate material, or a combination thereof.

[0012] In some embodiments, the negative electrode active material further includes a carbon coating layer covering the matrix and / or the silicon-carbon composite material.

[0013] In some embodiments, the carbon material includes one or more of a graphite material, a hard carbon material, a soft carbon material, or a combination thereof.

[0014] In some embodiments, the silicon-carbon composite material includes silicon crystallites, and the crystallite size of the silicon crystallites is 20 nm or less.

[0015] In some embodiments, the volume median particle size D V 50 of the negative electrode active material is 1 to 10 μm.

[0016] In some embodiments, the peak intensities of the first sub-peak and the second sub-peak are both less than 2000, for example 1500.

[0017] In a second aspect, the present application provides a method for manufacturing a negative electrode active material, The present invention provides a matrix and a vapor deposition apparatus, and includes step S1 of placing the matrix in a deposition furnace, pre-purging it with an inert gas, and preheating it to 200-300°C, Step S2 includes introducing a gas into the vapor deposition apparatus in a first mode, wherein the first mode includes simultaneously introducing a silicon source gas and a carbon source gas into the vapor deposition apparatus. Step S3 includes reacting a silicon source gas with a carbon source gas to deposit the reaction product onto a matrix, thereby forming a silicon-carbon composite material on the matrix. X-ray photoelectron spectroscopy (XPS) of the silicon-carbon composite material shows a Si2p peak, and after peak splitting, the following subpeaks can be formed from the Si2p peak. The first subpeak has a binding energy of 99.5-99.9 eV, and It includes a second subpeak with a binding energy of 98.7–99.1 eV, The peak area ratio between the first subpeak and the second subpeak is 1 to 2:1.

[0018] In some embodiments, step S2 includes simultaneously introducing a silicon source gas, a carbon source gas, and an inert gas into the vapor deposition apparatus.

[0019] In some embodiments, step S2 is, (1) The inert gas is characterized by being one or more of nitrogen gas and argon gas, and (2) The flow rate of the inert gas introduced into the vapor deposition apparatus includes one or more of the characteristics that account for 30-85 volume percent of the total gas flow rate introduced.

[0020] In some embodiments, step S2 involves introducing gas into the vapor deposition apparatus in a first mode and maintaining the pressure inside the apparatus at 200-600 Pa higher than standard atmospheric pressure.

[0021] In some embodiments, step S3 is, (1) Characteristics of step S3 being performed at 400-800°C, (2) Step S3 has one or more of the characteristics of lasting 1 to 12 hours.

[0022] In some embodiments, after step S3, The process further includes step S4, in which a carbon material is deposited onto the product of step S3.

[0023] In some embodiments, step S4 is, Operation S4a, which involves introducing a gas into a vapor deposition apparatus in a second mode after forming a silicon-carbon composite material, wherein the second mode includes simultaneously introducing a carbon source gas and an inert gas into the vapor deposition apparatus, with the proportion of the carbon source gas being 5% to 15% and the proportion of the inert gas being 85% to 95%, The procedure includes operation S4b, which involves decomposing a carbon source gas into carbon materials and depositing them onto a silicon-carbon composite material.

[0024] In some embodiments, operation S4b is, (1) Characteristics of step S4b being performed at 700~850℃, (2) Step S4b has one or more of the features of lasting 1 to 6 hours.

[0025] In a third aspect, the present application provides a negative electrode active material manufactured by the method described in any one of the above-described items.

[0026] In a fourth aspect, the present application provides a secondary battery comprising the negative electrode active material described in any one of the above paragraphs.

[0027] In a fifth aspect, the present application provides an electrical device including the above-mentioned secondary battery. [Effects of the Invention]

[0028] One or more embodiments of the present application are (1) The specific capacity of the negative electrode active material is high. (2) The negative electrode active material has a long cycle life. (3) The cost of the method for manufacturing the negative electrode active material is low, (4) The method for producing the negative electrode active material has one or more beneficial effects, such as high efficiency. [Brief explanation of the drawing]

[0029] [Figure 1] These are XPS spectra of negative electrode active materials from several examples and comparative examples of the present invention. [Figure 2] These are the XRD spectra of the negative electrode active material in several examples and comparative examples of the present invention. [Figure 3] These are the charge-discharge curves for the first cycle of a button-type battery according to several embodiments and comparative examples of the present invention. [Figure 4] These are capacity retention-cycle number curves for all batteries based on several embodiments and comparative examples of the present invention. [Figure 5] This is a schematic diagram showing a secondary battery according to one embodiment of the present invention. [Figure 6] Figure 5 is an exploded view showing a secondary battery according to one embodiment of the present invention. [Figure 7] This is a schematic diagram showing a battery module according to one embodiment of the present invention. [Figure 8] This is a schematic diagram showing a battery pack according to one embodiment of the present invention. [Figure 9] Figure 8 is an exploded view showing a battery pack according to one embodiment of the present invention. [Figure 10] This is a schematic diagram showing an electrical device that uses a secondary battery as a power source according to one embodiment of the present invention. [Modes for carrying out the invention]

[0030] The following describes in detail embodiments specifically disclosing the negative electrode active material and its manufacturing method, positive electrode sheet, negative electrode sheet, secondary battery, battery module, battery pack, and electrical device of this application, with appropriate reference to the drawings. However, unnecessary details may be omitted. For example, detailed descriptions of already well-known matters and redundant descriptions of the same actual structure may be omitted. This is to avoid making the following description unnecessarily long and to facilitate understanding for those skilled in the art. The drawings and the following description are provided to enable those skilled in the art to fully understand this application and do not limit the subject matter described in the claims.

[0031] The “range” disclosed in this application is limited in the form of a lower and upper limit, and a given range is limited by selecting one lower limit and one upper limit, and the boundaries of the special range are limited by the selected lower and upper limits. The range thus limited may include or exclude boundary values ​​and can be any combination, that is, any lower limit can be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are listed for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also expected. Furthermore, if the minimum range values ​​1 and 2 and the maximum range values ​​3, 4 and 5 are listed, then the following ranges, 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5, are all expected. In this application, unless otherwise stated, the numerical range “ab” is an abbreviated representation of any combination of real numbers from a to b, where both a and b are real numbers. For example, the numerical range "0-5" refers to all real numbers between "0-5" listed herein, and "0-5" is simply an abbreviated representation of combinations of these numbers. Also, when a parameter indicates an integer ≥ 2, it is equivalent to disclosing that the parameter is an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0032] Unless otherwise specified, all embodiments and preferred embodiments of the present application can be combined to form new technical solutions.

[0033] Unless otherwise specified, all technical features and preferred technical features of this application can be combined to form new technical solutions.

[0034] Unless otherwise specified, all steps of the present invention may be performed sequentially or randomly, but it is preferable to perform them sequentially. For example, "The method includes steps (a) and (b)" means that the method may include steps (a) and (b) performed sequentially, or steps (b) and (a) performed sequentially. For example, "The method described above may include step (c)" means that step (c) can be added to the method in any order, for example, the method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b).

[0035] Unless otherwise specified, the terms “equipment” and “include” as used in this application may be non-limiting or limiting. For example, “equipment” and “include” may further equip or include other components not listed, or they may equip or include only the listed components.

[0036] Unless otherwise specified, the term “or” in this application is inclusive. For example, the phrase “A or B” means “A, B, or both A and B.” More specifically, any of the following conditions satisfy the “A or B” condition: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) but B is true (or exists); or both A and B are true (or exist).

[0037] [Secondary battery] Secondary batteries, also known as rechargeable batteries or storage batteries, are batteries that can be used continuously by reactivating their active material through charging after discharge.

[0038] Typically, a secondary battery includes a positive electrode sheet, a negative electrode sheet, a separator, and an electrolyte. During the battery charging and discharging process, active ions (e.g., lithium ions) intercept and deintercept between the positive and negative electrode sheets. The separator is placed between the positive and negative electrode sheets and primarily serves to prevent short circuits between the positive and negative electrodes, while simultaneously allowing active ions to pass through. The electrolyte is located between the positive and negative electrode sheets and primarily serves to conduct active ions.

[0039] [Negative electrode sheet] The negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector, the negative electrode film layer includes a negative electrode active material, and the negative electrode active material is the negative electrode active material described in any one of the present claims.

[0040] For example, a negative electrode current collector has two opposing surfaces in the thickness direction of itself, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0041] In some embodiments, a metal foil sheet or a composite current collector can be used as the negative electrode current collector. For example, copper foil can be used as the metal foil sheet. The composite current collector may include a polymer material substrate layer and a metal layer formed on at least one surface of the polymer material substrate layer. The composite current collector can be formed by forming a metal material (such as copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0042] In some embodiments, the negative electrode film layer preferably further comprises a binder. For example, the binder can be selected from at least one of styrene-butadiene rubber (SBR), polyacrylic acid (PAA), sodium polyacrylate (PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), polymethacrylic acid (PMAA), and carboxymethyl chitosan (CMCS).

[0043] In some embodiments, the negative electrode film layer preferably further contains a conductive agent. For example, the conductive agent can be selected from at least one of superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0044] In some embodiments, the negative electrode film layer preferably further contains other auxiliary agents such as a thickening agent (e.g., sodium carboxymethylcellulose (CMC-Na)).

[0045] In some embodiments, a negative electrode sheet can be manufactured as follows: components for manufacturing the negative electrode sheet, such as a negative electrode active material, a conductive agent, a binder, and any other components, are dispersed in a solvent (e.g., deionized water) to form a negative electrode slurry; the negative electrode slurry is applied to a negative electrode current collector; and after processes such as drying and cold pressing, a negative electrode sheet can be obtained.

[0046] [Negative electrode active material] In some embodiments, the present application provides a negative electrode active material comprising a silicon-carbon composite material, wherein X-ray photoelectron spectroscopy (XPS) of the silicon-carbon composite material has a Si2p spectrum, the Si2p spectrum has at least one characteristic peak, and the characteristic peak can form the following subpeaks after peak splitting: The first subpeak has a binding energy of 99.5-99.9 eV, and It includes a second subpeak with a binding energy of 98.7–99.1 eV, The peak area ratio between the first subpeak and the second subpeak is 1 to 2:1.

[0047] The anode active material of the above-described method has a high specific capacity and a long cycle life. The peak area ratio of the first subpeak to the second subpeak is important, ideally between 1 and 2:1. If the peak area ratio is less than 1, it indicates a high pure silicon content in the anode active material and large silicon crystal grains, which is unfavorable for the lifespan. If the peak area ratio is greater than 2, it indicates that the carbon content in the anode active material is too high, resulting in a low specific capacity of the active material and poor initial performance.

[0048] In some embodiments, the binding energy of the first subpeak refers to the binding energy corresponding to the peak value point of the first subpeak.

[0049] In some embodiments, the binding energy of the second subpeak refers to the binding energy corresponding to the peak value point of the second subpeak.

[0050] In some embodiments, the first and second subpeaks have symmetrical peak shapes, such as peaks that match a Gaussian function or a Lorentz function.

[0051] In some implementations, the binding energy of the first subpeak is 99.6–99.8 eV, for example, 99.7 eV.

[0052] In some implementations, the binding energy of the second subpeak is 98.8–99.0 eV, for example, 98.9 eV.

[0053] In some implementations, the peak area ratio of the first subpeak to the second subpeak is 1.5 to 2:1, for example 1.6 to 1.8:1, for example 1.7:1.

[0054] In some embodiments, the anode active material has one or more of the following characteristics: (1) The binding energy of the first subpeak corresponds to the binding energy of the Si-C bond. (2) The binding energy of the second subpeak corresponds to the binding energy of the Si-Si bond, and based on this, the anode active material has further improved specific capacity, initial effect and / or cycle life. (3) The binding energy of the first subpeak is 99.6 to 99.8 eV, e.g., 99.7 eV. (4) The binding energy of the second subpeak is 98.8 to 99.0 eV, e.g., 98.9 eV. (5) The peak area ratio of the first subpeak to the second subpeak is 1.5 to 2:1. (6) The silicon content in the silicon-carbon composite material is 95-99.9 wt% (e.g., 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, or 99.5 wt%), and the carbon content is 0.1-5 wt% (e.g., 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%).

[0055] Based on this, the negative electrode active material is used in secondary batteries, which exhibit further improved specific capacity, initial performance, and / or cycle life.

[0056] In some embodiments, the anode active material comprises a matrix and the silicon-carbon composite material, wherein the silicon-carbon composite material is attached to the matrix. Based on this, the anode active material has further improved specific capacity, initial performance, and / or cycle life.

[0057] In some embodiments, the matrix has a porous internal structure, and the silicon-carbon composite material is attached to the outer surface of the matrix and / or within the voids of the porous internal structure. Based on this, the negative electrode active material has further improved specific capacity, initial effect, and / or cycle life.

[0058] In some embodiments, the matrix material includes one or more of the following: carbon material, silicon material, lithium titanate material, or a combination thereof. Based on this, the negative electrode active material has further improved specific capacity, initial effect, and / or cycle life.

[0059] In some embodiments, the anode active material further comprises a carbon coating layer covering the matrix and / or the silicon-carbon composite material. Based on this, the anode active material has further improved specific capacity, initial performance, and / or cycle life.

[0060] In some embodiments, the carbon material includes one or more of graphite materials, hard carbon materials, soft carbon materials, or combinations thereof. Based on this, the negative electrode active material has further improved specific capacity, initial effect, and / or cycle life.

[0061] In some embodiments, the silicon-carbon composite material includes silicon crystal grains with a crystal grain size of 20 nm or less. Based on this, the negative electrode active material has further improved specific capacity, initial effect, and / or cycle life.

[0062] In some embodiments, the volume median particle size D of the negative electrode active material V 50 is 1-10 μm (e.g., 2 μm, 4 μm, 6 μm, or 8 μm). Based on this, the negative electrode active material has further improved specific capacity, initial performance, and / or cycle life.

[0063] In some embodiments, the peak intensities of both the first subpeak and the second subpeak are less than 2000, for example, less than 1500.

[0064] In some embodiments, the present application provides a method for producing a negative electrode active material. The present invention provides a matrix and a vapor deposition apparatus, and includes step S1 of placing the matrix in a deposition furnace, pre-purging it with an inert gas, and preheating it to 200-300°C, Step S2 of introducing a gas into the vapor deposition apparatus in a first mode, wherein the first mode is a step S2 of simultaneously introducing a silicon source gas and a carbon source gas into the vapor deposition apparatus. Step S3 includes reacting a silicon source gas with a carbon source gas to deposit the reaction product onto a matrix, thereby forming a silicon-carbon composite material on the matrix. X-ray photoelectron spectroscopy (XPS) of the silicon-carbon composite material shows a Si2p peak, and after peak splitting, the following subpeaks can be formed from the Si2p peak. The first subpeak has a binding energy of 99.5-99.9 eV, and It includes a second subpeak with a binding energy of 98.7–99.1 eV, The peak area ratio between the first subpeak and the second subpeak is 1 to 2:1.

[0065] The negative electrode active material obtained by this method has improved specific capacity, initial performance, and / or cycle life.

[0066] In some embodiments, step S2 includes simultaneously introducing a silicon source gas, a carbon source gas, and an inert gas into the vapor deposition apparatus. The negative electrode active material obtained based on this means has improved specific capacity, initial effect, and / or cycle life.

[0067] In some embodiments, step S2 is, (1) The inert gas is characterized by being one or more of nitrogen gas and argon gas, and (2) The flow rate of the inert gas introduced into the vapor deposition apparatus includes one or more of the following characteristics, accounting for 30-85 volume percent of the total gas flow rate introduced. The negative electrode active material obtained by this means has improved specific capacity, initial effect and / or cycle life.

[0068] In some embodiments, step S2 involves introducing gas into the vapor deposition apparatus in a first mode and maintaining the pressure inside the apparatus at 200-600 Pa (e.g., 300 Pa, 400 Pa, 500 Pa) higher than standard atmospheric pressure. The negative electrode active material obtained based on this means has improved specific capacity, initial effect, and / or cycle life.

[0069] In some embodiments, step S3 is, (1) The characteristics of step S3 being performed at 400-800°C (e.g., 500°C, 600°C, or 700°C), (2) Step S3 includes one or more of the features that last from 1 to 12 hours (e.g., 2 hours, 4 hours, 6 hours, 8 hours, or 10 hours). The negative electrode active material obtained by this means has improved specific capacity, initial effect and / or cycle life.

[0070] In some embodiments, after step S3, The method further includes step S4, in which a carbon material is deposited onto the product of step S3. The negative electrode active material obtained by this means has improved specific capacity, initial effect, and / or cycle life.

[0071] In some embodiments, step S4 is, After forming the silicon-carbon composite material, a gas is introduced into the vapor deposition apparatus in a second mode, the second mode in which a carbon source gas and an inert gas are introduced into the vapor deposition apparatus simultaneously, the proportion of the carbon source gas being 5% to 15% and the proportion of the inert gas being 85% to 95% in operation S4a. The method includes operation S4b, in which a carbon source gas is decomposed into a carbon material and deposited onto a silicon-carbon composite material. The negative electrode active material obtained by this means has improved specific capacity, initial effect and / or cycle life.

[0072] In some embodiments, operation S4b is, (1) Characteristics of step S4b being performed at 700-850°C (e.g., 750-800°C), and (2) Step S4b has one or more characteristics of lasting 1-6 hours (e.g., 2 hours, 3 hours, 4 hours, or 5 hours). The negative electrode active material obtained by this means has improved specific capacity, initial effect, and / or cycle life.

[0073] In some embodiments, the present application provides a negative electrode active material manufactured by the method described in any one of the above-described items.

[0074] In some embodiments, the present application provides a secondary battery comprising the negative electrode active material described in any one of the above-mentioned items.

[0075] In some embodiments, the present application provides an electrical device including the above-mentioned secondary battery.

[0076] [Positive electrode sheet] In some embodiments, the positive electrode sheet typically includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. The positive electrode film layer includes a positive electrode active material.

[0077] For example, a positive electrode current collector has two opposing surfaces in the thickness direction of itself, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0078] In some embodiments, a metal foil sheet or a composite current collector can be used as the positive electrode current collector. For example, aluminum foil can be used as the metal foil sheet. A composite current collector includes a polymer material substrate layer and a metal layer formed on at least one surface of the polymer material substrate layer. A composite current collector can be formed by forming a metal material (such as aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy) on a polymer material substrate (for example, a substrate such as polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0079] In some embodiments, cathode active materials that are well-known in the art for use in batteries can be employed. By way of example, the cathode active material can include at least one of olivine-structured lithium-containing phosphates, lithium transition metal oxides, and their respective modified compounds. The present application is not limited to these materials, and conventional materials that can be used as other battery cathode active materials may also be used. These cathode active materials may be used alone or in combination of two or more. Examples of lithium transition metal oxides include cobalt lithium oxide (e.g., LiCoO2), lithium nickel oxide (e.g., LiNiO2), lithium manganese oxide (e.g., LiMnO2, LiMn2O4), lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide (e.g., LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (which can also be abbreviated as NCM 333 ), LiNi 0.5 Co 0.2 Mn 0.3 O2 (which can also be abbreviated as NCM 523 ), LiNi 0.5 Co 0.25 Mn 0.25 O2 (which can also be abbreviated as NCM 211 ), LiNi 0.6 Co 0.2 Mn 0.2 O2 (which can also be abbreviated as NCM 622 ), LiNi 0.8 Co 0.1 Mn 0.1 O2 (which can also be abbreviated as NCM 811 ), lithium nickel cobalt aluminum oxide (e.g., LiNi 0.85 Co 0.15 Al 0.05The olivine structure lithium-containing phosphate includes, but is not limited to, at least one of O2 and its modified compounds. Examples of olivine structure lithium-containing phosphates include, but is not limited to, at least one of lithium iron phosphate (e.g., LiFePO4 (which can also be abbreviated as LFP)), lithium iron phosphate and carbon composites, lithium manganese phosphate (e.g., LiMnPO4), lithium manganese phosphate and carbon composites, lithium iron manganese phosphate, and lithium iron manganese phosphate and carbon composites.

[0080] In some embodiments, the positive electrode film layer preferably further comprises a binder. For example, the binder may include at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resins.

[0081] In some embodiments, the cathode film layer preferably further contains a conductive agent. For example, the conductive agent may include at least one of superconducting carbon, acetylene black, carbon black, cochin black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0082] In some embodiments, a positive electrode sheet can be manufactured as follows: components for manufacturing the positive electrode sheet, such as a positive electrode active material, a conductive agent, and any other components of a binder, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry; the positive electrode slurry is applied to a positive electrode current collector; and after processes such as drying and cold pressing, a positive electrode sheet can be obtained.

[0083] [Electrolyte] The electrolyte plays a role in conducting ions between the positive electrode sheet and the negative electrode sheet. This application is not specifically limited to the type of electrolyte and can be selected as needed. For example, the electrolyte can be a liquid, a gel, or an all-solid.

[0084] In some embodiments, the electrolyte is liquid and comprises an electrolyte salt and a solvent.

[0085] In some embodiments, the electrolyte salt can be selected from at least one of lithium hexafluoride phosphate, lithium tetrafluoroborate, lithium perchlorate, lithium hexafluoride arsenate, lithium difluorosulfonylimide, lithium bistrifluoromethanesulfonylimide, lithium trifluoromethanesulfonate, lithium difluorophosphate, lithium difluorooxalate borate, lithium bis(oxalate)borate, lithium difluorobis(oxalate)phosphate, and lithium tetrafluorooxalate phosphate.

[0086] In some embodiments, the solvent can be selected from at least one of ethylene carbonate, propylene carbonate, ethyl methyl carbonate, diethyl carbonate, dimethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, butylene carbonate, fluoroethylene carbonate, methyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, ethyl butyrate, 1,4-butyrolactone, sulfolane, dimethyl sulfone, methyl ethyl sulfone, and diethyl sulfone.

[0087] In some embodiments, the electrolyte preferably further contains additives. For example, the additives may include negative electrode film forming additives, positive electrode film forming additives, and additives that can improve certain performance characteristics of the battery, such as additives that improve the overcharge performance of the battery and additives that improve the high-temperature or low-temperature performance of the battery.

[0088] [Separator] In some embodiments, the secondary battery further includes a separator. The present application is not particularly limited to the type of separator, and any known porous structure separator having good chemical and mechanical stability can be selected.

[0089] In some embodiments, the material of the separator can be selected from at least one of glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator is not particularly limited and may be a single-layer thin film or a multilayer composite thin film. If the separator is a multilayer composite thin film, the materials of each layer are not particularly limited and may be the same or different.

[0090] In some embodiments, the positive electrode sheet, negative electrode sheet, and separator can be manufactured into an electrode assembly by a winding process or a lamination process.

[0091] In some embodiments, the secondary battery may include an enclosure. The enclosure can be used to seal the electrode assembly and electrolyte.

[0092] In some embodiments, the casing of the secondary battery may be a hard shell, such as a rigid plastic shell, an aluminum shell, or a steel shell. The casing of the secondary battery may also be a soft bag, such as a pouch soft bag. The material of the soft bag may be plastic, and examples of plastics include polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0093] The present invention does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, Figure 5 is an example of a rectangular secondary battery 5.

[0094] In some embodiments, referring to Figure 6, the exterior may include a housing 51 and a cover plate 53. The housing 51 may include a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates may enclose a storage chamber. The housing 51 has an opening that communicates with the storage chamber, and the cover plate 53 may cover the opening to close the storage chamber. The positive electrode sheet, negative electrode sheet, and separator may form an electrode assembly 52 by a winding or laminating process. The electrode assembly 52 is sealed inside the storage chamber. The electrolyte permeates into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and can be selected by those skilled in the art according to specific practical requirements.

[0095] In some embodiments, the secondary battery can be assembled as a battery module, and the number of secondary batteries included in the battery module may be one or more, and a person skilled in the art can select the specific number depending on the application and capacity of the battery module.

[0096] Figure 7 shows an example of a battery module 4. Referring to Figure 7, in the battery module 4, multiple secondary batteries 5 are arranged sequentially along the length of the battery module 4. Of course, they may be distributed in any other manner. Furthermore, the multiple secondary batteries 5 can be secured with fasteners.

[0097] Preferably, the battery module 4 may further include an external case having storage space, in which a plurality of secondary batteries 5 are housed.

[0098] In some embodiments, the battery modules may be further assembled as a battery pack, and the number of battery modules included in the battery pack may be one or more, and a person skilled in the art can select the specific number depending on the application and capacity of the battery modules.

[0099] Figures 8 and 9 show an example of a battery pack 1. Referring to Figures 8 and 9, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided inside the battery box. The battery box includes an upper box 2 and a lower box 3, and the upper box 2 can be covered by the lower box 3, forming a closed space for housing the battery modules 4. The plurality of battery modules 4 can be arranged inside the battery box in any manner.

[0100] Furthermore, the present application provides an electrical device comprising at least one of the secondary battery, battery module, or battery pack provided herein. The secondary battery, battery module, or battery pack can be used as a power source for the electrical device and can also be used as an energy storage unit for the electrical device. The electrical device includes, but is not limited to, mobile devices (e.g., mobile phones, 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.), trains, ships and satellites, and energy storage systems.

[0101] As the electrical device, a secondary battery, battery module, or battery pack can be selected depending on the requirements of use.

[0102] Figure 10 shows an example of an electrical device. This electrical device may be a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of the secondary battery in this electrical device, a battery pack or battery module can be used.

[0103] Examples of the present application are described below. The examples described below are illustrative and are used solely for interpreting the present application and should not be understood as limiting the present application. Where no specific technique or conditions are shown in the examples, the application should be carried out in accordance with the technique or conditions described in the literature of the art or in accordance with the product specification. Where the manufacturer of the reagents or equipment used is not indicated, they are conventional products available on the market.

[0104] Comparative Example 1 A commercially available silicone material is provided as the negative electrode active material for Comparative Example 1.

[0105] The composition of the silicone material is Li 8 wt%, Si 52 wt%, O 35.8 wt%, and C 4.2 wt%.

[0106] Example 1 In S1, a silicone material similar to that in Comparative Example 1 is provided as the matrix. A chemical vapor deposition (CVD) apparatus is provided. 1 kg of the matrix is ​​placed in the reaction chamber of the chemical vapor deposition apparatus. The reaction chamber is purged with nitrogen gas and the temperature of the reaction chamber is raised to 200°C. In S2, a mixed gas is introduced into the reaction chamber in the first mode, which means introducing a mixed gas into the reaction chamber in a volume ratio of monosilane:acetylene:nitrogen gas = 20%:5%:75%, with a total gas flow rate of 5 L / min, and controlling the pressure inside the reaction chamber to be higher than atmospheric pressure of 200 Pa. In step S3, the temperature in the reaction chamber is raised to 600°C, and the reaction product (silicon-carbon composite material) formed by the reaction of monosilane and acetylene is deposited onto the matrix, with the deposition continuing for 4 hours. In S4, the mixed gas is introduced into the reaction chamber in the second mode, which refers to introducing the mixed gas into the reaction chamber in a volume ratio of acetylene:nitrogen gas = 5%:95%. In step S5, the temperature in the reaction chamber is raised to 850°C, causing the acetylene to decompose and form a carbon material which is then deposited onto the surface of the product from the previous step. The deposition process continues for 2 hours. After cooling the product, it is removed from the reaction chamber and sieved through a 325-mesh sieve. The negative electrode active material of Example 1 is obtained.

[0107] The negative electrode active material of Example 1 includes a matrix, a first coating layer deposited on the surface of the matrix, and a second coating layer deposited on the surface of the first coating layer. The matrix material is a silicone material. The first coating layer material is a silicon-carbon composite material. The second coating layer material is a carbon material.

[0108] Examples 2-3 The difference between Example 2 and Example 1 is that in step S2, the ratio of monosilane, acetylene, and nitrogen gas is 20%, 7%, and 73%. The difference between Example 3 and Example 1 is that in step S2, the adjusted monosilane:acetylene:nitrogen gas ratio is 20%:2%:78%.

[0109] Comparative Examples 2-3 The difference between Comparative Example 2 and Example 1 is that in step S2, the ratio of monosilane, acetylene, and nitrogen gas is 20%:10%:70%. The difference between Comparative Example 3 and Example 1 is that in step S2, the ratio of monosilane, acetylene, and nitrogen gas is 20%:0.5%:79.5%.

[0110] Manufacturing of button-type batteries The negative electrode active materials from Comparative Example 1 and Example 1 were used to assemble a button-type lithium-ion battery, specifically as follows: A negative electrode active material, conductive carbon black, and polyacrylic acid as a binder are mixed in a mass ratio of 8:1:1. Deionized water is added as a solvent, and the mixture is uniformly stirred with a stirrer to obtain a negative electrode slurry with a solid content of 45 wt%. The negative electrode slurry is uniformly applied to the copper foil of the negative electrode current collector and dried at 85°C. After cold pressing, an electrode sheet is obtained. A button cell is obtained by using metallic lithium as the counter electrode, injecting the electrolyte using a Celgard 2400 separator, and assembling the components. The solvent of the electrolyte is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), with a volume ratio of EC, EMC, and DEC of 20:20:60. The solute of the electrolyte is LiPF6, with a concentration of 1 mol / L. The electrolyte further contains fluoroethylene carbonate (FEC) as an additive, with an FEC content of 5 wt%.

[0111] Analysis and Detection Powder performance test 1) XPS detection An X-ray photoelectron spectrometer (Thermo Scientific ESCALAB Xi+) was used to test the negative electrode active materials of the examples and comparative examples, and the Si2p energy spectra of the materials were obtained. Peak fitting was performed on the characteristic peaks of the Si2p energy spectra using XPSpeak software.

[0112] The Si2p energy spectrum of the negative electrode active material of Comparative Example 1 has one characteristic peak in the range of 100 to 104 eV, and the bond energy of this characteristic peak is 102.3 eV, which corresponds to the bond energy of the Si-OC bond.

[0113] Figure 1 shows the Si2p energy spectrum of the negative electrode active material of Example 1. As shown in Figure 1, the Si2p energy spectrum of the negative electrode active material of Example 1 has the original curve 100. The original curve 100 has one characteristic peak each at 98-101 eV and 101-105 eV. After peak fitting is performed on the characteristic peak at 98-101 eV, a fitting curve 200 is formed. The fitting curve 200 appears as a superposition of two subpeaks at the 101-105 eV position, and the two subpeaks are, The first subpeak 201 has a bond energy of 99.7 eV (corresponding to the bond energy of the Si-C bond), and It includes a second subpeak 202 with a bond energy of 98.9 eV (corresponding to the bond energy of the Si-Si bond), Peak area A of the first subpeak 201 Si-C and the peak area A of the second subpeak 202 Si-Si Ratio A Si-C / A Si-Si The value is 1.7. The peak intensities of both the first and second subpeaks are less than 2000. A for each example and comparative example. Si-C / A Si-Si The test results are shown in Table 2.

[0114] 2) XRD test, crystal grain size calculation, laser diffraction grain size distribution

[0115] In accordance with the JIS K 0131-1996 test method, the XRD spectra of the silicon-carbon material described above were obtained by testing with a Bruker D8 Discover X-ray diffractometer, with a test angle range of 20°-80°. After obtaining the data, the crystal grain size of the silicon(111) crystal plane corresponding to 28.5°±0.1° was obtained by fitting with X'Pert Highscore plus software and calculating using Scherrer's formula.

[0116] Figure 2 shows the XRD spectra of Example 1 and Comparative Example 1. Diffraction peaks of Li2SiO3 and Si can be observed from the XRD spectrum of the negative electrode active material in Comparative Example 1. The distribution of diffraction peaks in the XRD spectrum of the negative electrode active material in Example 1 is basically consistent with that of the Comparative Example, but the diffraction peak intensity is weaker. This suggests that in Example 1, the silicon-carbon composite material and carbon material deposited on the matrix exhibit almost no diffraction peaks and basically present an amorphous structure.

[0117] The silicon grain sizes calculated based on Scherrer's formula are shown in the table below. The average size of silicon grains in the negative electrode active material of Comparative Example 1 and Example 1 is in the range of 6 nm to 8 nm.

[0118] The table below shows the particle size distribution data of the negative electrode active material for the examples and comparative examples, measured based on laser diffraction. Volume distribution particle size data Dv10 (μm), Dv50 (μm), Dv90 (μm), and Dv99 (μm), and quantity particle size distribution data D N Includes particles up to 10 μm. For the particle size test method, refer to the general laser diffraction method in this field, for example, the GB / T 19077-2016 particle size distribution laser diffraction method. The particle size distribution data of the negative electrode active material for Example 1 and Comparative Example 1 are shown in Table 1.

[0119] [Table 1]

[0120] 3) Detection of elemental components The elemental components of the negative electrode active material manufactured in Example 1 are detected according to the following test method. Carbon content test: The material carbon content is obtained by testing with an HSC-140 carbon content analyzer in accordance with the GB / T 20123-2006 / ISO 15350:2000 test standard.

[0121] Lithium, Silicon, and Oxygen Element Content Test: Lithium and silicon content are obtained by testing with an inductively coupled plasma emission spectrometer (ICP, iICAP 7400 instrument) in accordance with standard EPA 6010D-2014. Oxygen content is calculated from the tested carbon content / lithium content / silicon content, where oxygen content = 100% - silicon content - carbon content - lithium content.

[0122] The negative electrode active material in Example 1 consists of Li 6.8 wt%, Si 57 wt%, O 29.7 wt%, and C 6.5 wt%.

[0123] In the negative electrode active material of Example 1, the silicon-carbon composite material constituting the first coating layer has a silicon content of 97.5% and a carbon content of 2.5% (calculated according to the silicon content / carbon content before and after deposition). The test results for each example and comparative example are shown in Table 2.

[0124] 4) Battery initial charge / discharge efficiency: Procedure for the initial cycle efficiency test: After assembly, let the button-type battery sit for 60 minutes. Lithium storage capacity: First, discharge at a constant current of 0.05C down to 5mV, then discharge at 50μA down to 5mV, and let stand for 10 minutes. Lithium escape capacity: Charges to 1.5V at 0.1C. The specific capacity-voltage curve for the initial lithium absorption-desorption cycle is shown in Figure 3. The initial cycle efficiency (abbreviated as initial effect) is calculated using the following formula: Initial effectiveness % = Lithium escape capacity / Lithium storage capacity The test results are shown in Table 2 below.

[0125] As can be seen from Table 2 and Figure 3 above, the negative electrode active material of Example 1 has significantly increased lithium escape capacity and lithium storage capacity compared to Comparative Example 1. The initial effect of the negative electrode active material of Example 1 is basically equivalent to that of Comparative Example 1. The test results of each example and comparative example are shown in Table 2.

[0126] 5) Detection of battery cycle life: The negative electrode active materials from the examples and comparative examples are assembled into a complete battery.

[0127] Method for preparing positive electrode slurry: The positive electrode NCM ternary material, the conductive agent Super P, and the binder polyvinylidene fluoride (PVDF) are mixed in a mass ratio of 97:1.5:1.5, N-methylpyrrolidone (NMP) is added as a solvent, and the mixture is uniformly stirred under the action of a vacuum stirrer to obtain a positive electrode slurry with a solid content of 77 wt%. The positive electrode slurry is uniformly applied to the aluminum foil of the positive electrode current collector and dried at 85°C. Next, it undergoes cold pressing, trimming, slitting, and cutting, and finally, it is dried for 4 hours under vacuum conditions at 85°C to obtain a preliminary positive electrode sheet.

[0128] Method for preparing the negative electrode slurry: A negative electrode active substance (90% graphite, 10% silicon), a conductive agent (containing CNTs), a thickener sodium carboxymethylcellulose (CMC), and a binder styrene-butadiene rubber (SBR) are mixed in a mass ratio of 96.2:1.3:1.0:1.5. Then, deionized water is added as a solvent, and the mixture is uniformly stirred under the action of a vacuum stirrer to obtain a negative electrode slurry with a solid content of 52%. The negative electrode slurry is uniformly applied to the first layer negative electrode film layer and dried at 85°C. Next, it undergoes cold pressing, trimming, slitting, and cutting, and finally, it is dried for 12 hours under vacuum conditions at 120°C to obtain a preliminary negative electrode sheet.

[0129] Method for preparing the electrolyte: The organic solvent is a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC), where the volume ratio of EC, EMC, and DEC is 20:20:60. In a glove box with an argon gas atmosphere and a water content of <10 ppm, a thoroughly dried lithium salt is dissolved in the above organic solvent, and then 10 wt% of fluoroethylene carbonate (FEC), an additive, is added and mixed uniformly to obtain the electrolyte. Here, the concentration of the lithium salt is 1 mol / L.

[0130] A positive electrode slurry is applied to an aluminum foil current collector to obtain a positive electrode sheet, and a negative electrode slurry is applied to a copper foil current collector to obtain a negative electrode sheet. The positive electrode sheet, separator, and negative electrode sheet are then stacked, wound up, placed in a battery case, and sealed with electrolyte to obtain a complete battery.

[0131] Charge-discharge cycle tests were performed on all batteries with a charge-discharge rate of 0.5C / 1C and a cutoff voltage of 2.5-4.25V. The capacity retention rate-cycle count curves obtained from the tests are shown in Figure 4. The 200-cycle retention rate test results for each example and comparative example are shown in Table 2 below.

[0132] As can be seen from Table 2 and Figure 4, after 200 cycles, the capacity retention rates of all batteries in Example 1 and Comparative Example 1 were 96.6% and 96.8%, respectively. Example 1's capacity retention rate was almost the same as that of Comparative Example 1, indicating that the material in Example 1 significantly improved the specific capacity while maintaining a good capacity retention rate.

[0133] 6) Testing the energy density of battery cells At 25°C, the batteries manufactured according to the examples and comparative examples were fully discharged at 1C, then fully charged at a rate of 1C, and fully discharged at a rate of 1C. The actual discharge energy at this time was recorded, and the batteries were weighed using an electronic balance at 25°C. The ratio of the actual discharge energy D / Wh of the battery at 1C to the battery weight m / kg is the actual energy density E of the battery, where E = D / m.

[0134] The total energy densities of the batteries in Example 1 and Comparative Example 1 were 276 Wh / kg and 266 Wh / kg, respectively, representing a 3.8% improvement in energy density. The test results for the energy density of each example and comparative example are shown in Table 2 below.

[0135] [Table 2]

[0136] The XPS Si2p spectra of the negative electrode active materials in Examples 1-3 show a peak area ratio of 1-2:1 between the first and second subpeaks after peak fitting. These negative electrode active materials are used in secondary batteries, which exhibit improved specific capacity, improved initial performance, and excellent cycle life.

[0137] In Comparative Example 3, the XPS Si2p spectrum of the anode active material, after peak fitting, shows that the peak area ratio between the first and second subpeaks is less than 1, indicating a high pure silicon content and large silicon grain size in the anode active material, which is unfavorable for lifespan. In Comparative Example 2, the peak area ratio between the first and second subpeaks is greater than 2, indicating that the carbon content in the anode active material is too high, resulting in a low specific capacity of the active material and poor initial performance.

[0138] This application is not limited to the embodiments described above. The embodiments described above are illustrative, and any embodiment that has a similar configuration and produces the same effects as the technical idea within the scope of the technical means of this application is included within the scope of the technical means of this application. Furthermore, various modifications of the embodiments that can be conceived by a person skilled in the art, and other forms constructed by combining some of the components of the embodiments, are also included within the scope of this application, as long as they do not depart from the spirit of this application. [Explanation of symbols]

[0139] 1 Battery pack 2 Upper box 3 Lower box 4 Battery Modules 5 Secondary battery 51 cases 52 Electrode Assembly 53 Top cover assembly, 11 Positive electrode current collector 112 Surface 12 Conductive base coating 13 Positive electrode membrane layer

Claims

1. A negative electrode active material comprising a silicon-carbon composite material, wherein the silicon-carbon composite material has a Si2p spectrum obtained by X-ray photoelectron spectroscopy (XPS), the Si2p spectrum has at least one characteristic peak, and the characteristic peak can form the following subpeaks after undergoing peak splitting processing. The first subpeak has a binding energy of 99.5–99.9 eV, and It includes a second subpeak with a binding energy of 98.7–99.1 eV, The peak area ratio between the first subpeak and the second subpeak is 1 to 2:

1. The negative electrode active material is a silicon-carbon composite material in which the silicon element content is 95 wt% to 99.9 wt% and the carbon element content is 0.1 wt% to 5 wt%.

2. (1) The characteristic that the bond energy of the first subpeak corresponds to the bond energy of the Si-C bond, (2) The characteristic that the bond energy of the second subpeak corresponds to the bond energy of the Si-Si bond, (3) The first subpeak has a binding energy of 99.6–99.8 eV. (4) The second subpeak has a binding energy of 98.8–99.0 eV. (5) The negative electrode active material according to claim 1, having one or more characteristics in which the peak area ratio of the first subpeak to the second subpeak is 1.5 to 2:

1.

3. The negative electrode active material according to claim 1, comprising a matrix and the silicon-carbon composite material, wherein the silicon-carbon composite material is attached to the matrix.

4. The matrix has a porous internal structure, and the silicon-carbon composite material is The outer surface of the matrix, and / or The negative electrode active material according to claim 3, which is attached to the voids in the porous internal structure.

5. The negative electrode active material according to claim 3, wherein the material of the matrix comprises one or more of a carbon material, a silicon material, a lithium titanate material, or a combination thereof.

6. The negative electrode active material according to any one of claims 3 to 5, further comprising a carbon coating layer covering the matrix and / or the silicon-carbon composite material.

7. The negative electrode active material according to claim 6, wherein the carbon material comprises one or more of a graphite material, a hard carbon material, a soft carbon material, or a combination thereof.

8. The silicon-carbon composite material is a negative electrode active material according to claim 1, comprising silicon crystal grains with a crystal grain size of 20 nm or less.

9. Volume median particle size D of the negative electrode active material Ｖ The negative electrode active material according to claim 1, wherein 50 is 1 to 10 μm.

10. The negative electrode material according to claim 1, wherein the peak intensities of both the first subpeak and the second subpeak are less than 2000.

11. A method for producing a negative electrode active material, The present invention provides a matrix and a vapor deposition apparatus, and includes step S1 of placing the matrix in a deposition furnace, pre-purging it with an inert gas, and preheating it to 200-300°C, Step S2 includes introducing a gas into the vapor deposition apparatus in a first mode, wherein the first mode includes simultaneously introducing a silicon source gas and a carbon source gas into the vapor deposition apparatus. Step S3 includes reacting a silicon source gas with a carbon source gas to deposit the reaction product onto a matrix, thereby forming a silicon-carbon composite material on the matrix. The X-ray photoelectron spectroscopy (XPS) of the silicon-carbon composite material yields a Si2p spectrum, the Si2p spectrum having at least one characteristic peak, and the characteristic peak can form the following subpeaks after peak splitting: The first subpeak has a binding energy of 99.5–99.9 eV, and It includes a second subpeak with a binding energy of 98.7–99.1 eV, A method for producing a negative electrode active material, wherein the peak area ratio of the first subpeak to the second subpeak is 1 to 2:

1.

12. Step S2 is, (1) The silicon source gas is characterized by being one or more of monosilane and disilane, and / or (2) The carbon source gas is characterized by being one or more of methane, ethylene, and acetylene, (3) The method according to claim 11, having one or more of the characteristics that the ratio of the volume flow rates of the silicon source gas to the carbon source gas is 2 to 10:

1.

13. The method according to claim 11, wherein in step S2, the first mode is to simultaneously introduce a silicon source gas, a carbon source gas, and an inert gas into a vapor deposition apparatus.

14. Step S2 is, (1) The inert gas is characterized by being one or more of nitrogen gas and argon gas, and (2) The method according to claim 13, wherein the flow rate of the inert gas introduced into the vapor deposition apparatus is 30-85 volume percent of the total flow rate of the gas introduced.

15. The method according to claim 11, wherein in step S2, gas is introduced into the vapor deposition apparatus in the first mode and the pressure inside the vapor deposition apparatus is maintained to be 200 to 600 Pa higher than standard atmospheric pressure.

16. Step S3 is, (1) Step S3 is characterized by being performed at 400 to 800°C, and / or (2) The method according to claim 11, having one or more of the characteristics that step S3 lasts for 1 to 12 hours.

17. After step S3, The method according to claim 11, further comprising step S4 of depositing a carbon material onto the product of step S3.

18. Step S4 is, After forming the silicon-carbon composite material, a gas is introduced into the vapor deposition apparatus in a second mode, the second mode including the simultaneous introduction of a carbon source gas and an inert gas into the vapor deposition apparatus, wherein the proportion of the carbon source gas is 5% to 15% and the proportion of the inert gas is 85% to 95% in operation S4a. The method according to claim 17, comprising operation S4b, which involves decomposing a carbon source gas into a carbon material and depositing it onto a silicon-carbon composite material.

19. Operation S4b is, (1) The characteristics of step S4b being performed at 700 to 850°C, and (2) The method according to claim 18, having one or more of the features that step S4b lasts for 1 to 6 hours.

20. A secondary battery comprising the negative electrode active material described in claim 1.

21. An electrical device including a secondary battery as described in claim 20.

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