Negative electrode active material, method for producing the same, secondary battery and electric consumer device including the same

Abstract

The present application provides a negative electrode active material, a method for manufacturing the same, a secondary battery including the same, and an electric consumption device. The negative electrode active material includes a carbon substrate and a filler. The graphitization degree of the carbon substrate is 87% or less. The carbon substrate includes a plurality of pore structures. At least a part of the filler is located in the pore structures of the carbon substrate, and the filler includes one or more of elements capable of alloying reaction with Li. The negative electrode active material according to the present application can have high specific capacity, high initial Coulomb efficiency, low volume expansion, high conductivity, and good cycle stability. Figure 1

Description

Technical Field

[0001] The present application belongs to the technical field of batteries, and specifically relates to a negative electrode active material, a method for manufacturing the same, a secondary battery including the same, and an electric consumer device.

Background Art

[0002] In recent years, secondary batteries have been widely used in many fields such as energy storage power systems such as hydraulic, thermal, wind, and solar power plants, and electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. In the process of the rapid development of secondary batteries, the requirements for their energy density have become higher. Carbon-based materials represented by graphite are the most commonly used negative electrode active materials in secondary batteries, but the capacity of such materials has approached the theoretical specific capacity. Non-carbon-based materials such as silicon-based materials, tin-based materials, and germanium-based materials have attracted wide attention because they have a high theoretical specific capacity. However, such negative electrode active materials generally have the disadvantages of large volume expansion, low initial Coulomb efficiency, and / or poor conductivity.

Summary of the Invention

[0003] An object of the present application is to provide a negative electrode active material having high specific capacity, high initial Coulomb efficiency, low volume expansion, high conductivity, and good cycle stability, a method for manufacturing the same, a secondary battery including the same, and an electric consumer device.

[0004] A first aspect of the present application provides a negative electrode active material including a carbon matrix and a filler, wherein the graphitization degree of the carbon matrix is 87% or less, the carbon matrix includes a plurality of pore structures, at least a part of the filler is located in the pore structures of the carbon matrix, and the filler includes one or more of elements capable of alloying with Li.

[0005] The inventors of the present invention have found through research that by providing a filler having a high specific capacity in the pore structure of a carbon matrix with a low graphitization degree (exceeding 0 and not exceeding 87%), the resulting negative electrode active material can have a high specific capacity, a high initial Coulombic efficiency, a low volume expansion, a high conductivity, and good cycle stability, and at the same time, a secondary battery can have a high energy density, a high initial Coulombic efficiency, and a long cycle life. The carbon matrix of the present application has a graphitization degree of not more than 87%, has the advantages of higher conductivity and higher initial Coulombic efficiency compared with the carbon matrix obtained by pore formation using a pore-forming agent, has a smaller volume expansion compared with natural graphite, and has the advantage of high cycle stability. Therefore, the negative electrode active material according to the present application can fully exert the advantage of the high specific capacity of the filler and can compensate for the disadvantages of the poor conductivity and low initial Coulombic efficiency of the filler. In addition, at least a part of the filler is located in the pore structure of the carbon matrix, so that the volume expansion of the filler can be reduced by the carbon matrix.

[0006] In any embodiment of the present application, the graphitization degree of the carbon matrix is 65% to 87%. This is advantageous for the negative electrode active material to better have a high specific capacity, a high initial Coulombic efficiency, a low volume expansion, a high conductivity, and good cycle stability.

[0007] In any embodiment of the present application, the element capable of alloying reaction with Li includes one or more of silicon element, tin element, and germanium element. This is advantageous for the negative electrode active material to have a high specific capacity.

[0008] In any embodiment of the present application, the filler includes one or more of silicon-based materials, tin-based materials, and germanium-based materials.

[0009] In any embodiment of the present application, the silicon-based material includes one or more of elemental silicon, silicon oxide, silicon carbon material, silicon nitride composite, and silicon alloy.

[0010] In any embodiment of the present application, the tin-based material includes one or more of tin alone, tin oxide, tin sulfide, tin phosphide, tin composite oxide, tin carbon material, and tin alloy material.

[0011] In any embodiment of the present application, the germanium-based material includes one or more of germanium alone, germanium oxide, germanium carbon material, germanium alloy material, and germanium salt.

[0012] In any embodiment of the present application, the filler includes a crystalline filler and / or an amorphous filler, and optionally includes a crystalline silicon-based material and / or an amorphous silicon-based material. The silicon-based material has a high specific capacity and is advantageous for improving the energy density of the secondary battery.

[0013] In any embodiment of the present application, the crystal grain size of the crystalline filler is 100 nm or less, and optionally 2 nm to 50 nm. When the crystalline filler has an appropriate crystal grain size, it is possible to improve the initial Coulomb efficiency of the secondary battery and avoid having a great adverse effect on the cycle performance and storage performance of the secondary battery.

[0014] In any embodiment of the present application, the filler includes one or more of a silicon-based material, a tin-based material, and a germanium-based material deposited by vapor deposition (also referred to as vapor growth), and optionally includes a silicon-based material deposited by vapor deposition.

[0015] In the present application, the negative electrode active material includes a (002) crystal plane peak at 26.4° and a (111) crystal plane peak at 28.6° in the X-ray diffraction spectrum measured by an X-ray diffractometer, and the ratio of the half-value width of the (002) crystal plane peak to the half-value width of the (111) crystal plane peak is 0.2 to 50, and optionally 0.2 to 20. By controlling the half-value width of the (002) crystal plane peak and the half-value width of the (111) crystal plane peak within an appropriate range, the carbon matrix has an appropriate graphitization degree, and the filler has an appropriate crystal grain size, so that the negative electrode active material has high specific capacity, high initial Coulomb efficiency, low volume expansion, high conductivity and good cycle stability.

[0016] In any embodiment of the present application, at least a part of the filler is located in the pore structure of the carbon matrix, and there is a gap between the filler and the carbon matrix. When there is a gap between the filler and the carbon matrix, a part of this gap can serve as a space for accommodating the volume expansion of the filler and relieve the stress generated during the expansion process of the filler, thereby further reducing the probability of particle crushing and pulverization.

[0017] In any embodiment of the present application, the negative electrode active material further includes a coating layer located on at least a part of the surface of the carbon matrix. Since the coating layer can prevent the filler and the electrolyte from coming into direct contact, it can reduce the side reaction of the electrolyte, reduce the consumption of active ions, improve the cycle performance of the secondary battery, improve the stability of the negative electrode slurry, and avoid the increase in the processing difficulty of the negative electrode slurry due to the reaction of the filler with solvent water or the like. In addition, the coating layer also plays a role in relieving the volume expansion of the filler, thereby being advantageous for improving the structural stability of the negative electrode active material and the electrochemical performance of the secondary battery.

[0018] In any embodiment of the present application, the coating layer includes one or more of a carbon material, a conductive polymer, a metal oxide, and a metal sulfide, and optionally includes a carbon material.

[0019] In any embodiment of the present application, the thickness of the coating layer is 100 nm or less, and optionally 10 nm to 100 nm. When the thickness of the coating layer is within the above range, the integrity of the coating layer is higher, and it is possible to more effectively avoid the contact between the filler and the electrolyte, so as to reduce the side reaction of the electrolyte and make the negative electrode active material have high specific capacity, high initial Coulomb efficiency and low volume expansion, which is advantageous.

[0020] In any embodiment of the present application, the negative electrode active material contains a carbon element and an element capable of alloying reaction with Li.

[0021] In any embodiment of the present application, the mass percentage of the carbon element in the negative electrode active material is 20 wt% to 80 wt%, and optionally 30 wt% to 70 wt%.

[0022] In any embodiment of the present application, the mass percentage of the element capable of alloying reaction with Li in the negative electrode active material is 20 wt% to 80 wt%, and optionally 30 wt% to 70 wt%.

[0023] When the content of the carbon element and / or the element capable of alloying reaction with Li in the negative electrode active material is within the above range, it is advantageous for the negative electrode active material to have both high specific capacity and high conductivity.

[0024] In any embodiment of the present application, the negative electrode active material further contains other elements, and the other elements include one or more of an oxygen element, a metal element and a nitrogen element.

[0025] In any embodiment of the present application, the total mass percentage of the other elements in the negative electrode active material is 20 wt% or less, and optionally 10 wt% or less.

[0026] In any embodiment of the present application, the initial Coulomb efficiency of the carbon matrix is 75% or more, and optionally 75% to 87%. Thereby, it is advantageous to improve the initial Coulomb efficiency of the negative electrode active material.

[0027] In any embodiment of the present application, the powder resistivity of the carbon matrix at a pressure of 16 MPa is 5×10 -2 Ω·cm or less, and optionally 3.5×10 -2 Ω·cm or less. This is advantageous for improving the conductivity of the negative electrode active material.

[0028] In any embodiment of the present application, the BET specific surface area of the carbon matrix is 50 m 2 / g to 1000 m 2 / g, and optionally 100 m 2 / g to 700 m 2 / g. Thereby, it is advantageous for the negative electrode active material to have an appropriate BET specific surface area, which can reduce the surface activity of the negative electrode active material, reduce the interfacial side reaction, reduce the film formation consumption of the SEI film, and further improve the first Coulomb efficiency and cycle performance of the secondary battery.

[0029] In any embodiment of the present application, the graphitization degree of the negative electrode active material is 65% or more, and optionally 65% to 87%. Thereby, it is advantageous for the negative electrode active material to better combine high first Coulomb efficiency, high conductivity, and good cycle stability.

[0030] In any embodiment of the present application, the first Coulomb efficiency of the negative electrode active material is 92% or more, and optionally 92% to 95%. Thereby, the irreversible consumption of active ions can be reduced, and the capacity performance and cycle performance of the secondary battery can be improved.

[0031] In any embodiment of the present application, the volume particle size Dv50 of the negative electrode active material is 3 μm to 50 μm, and optionally 5 μm to 20 μm.

[0032] In any embodiment of the present application, the volume particle size Dv90 of the negative electrode active material is 60 μm or less, and optionally 20 μm to 50 μm.

[0033] In any embodiment of the present application, the particle size distribution width (Dv90 - Dv10) / Dv50 of the negative electrode active material is 1.0 to 3.0, and optionally 1.0 to 2.0.

[0034] When at least one of the volume particle size Dv50, volume particle size Dv90, and particle size distribution width (Dv90 - Dv10) / Dv50 of the negative electrode active material is within the above range, it contributes to the reduction of the surface activity of the negative electrode active material, the reduction of interface side reactions, and the reduction of the film formation consumption of the SEI film, and is also advantageous for improving the active ion and electron transmission performance. Therefore, the cycle performance of the secondary battery can be further improved.

[0035] In any embodiment of the present application, the BET specific surface area of the negative electrode active material is 2 m 2 / g to 100 m 2 / g, and optionally 2 m 2 / g to 30 m 2 / g. When the BET specific surface area of the negative electrode active material is within the above range, it contributes to the reduction of interface activity, the reduction of interface side reactions, and the reduction of the film formation consumption of the SEI film. Therefore, the initial Coulomb efficiency and cycle performance of the secondary battery can be improved.

[0036] In any embodiment of the present application, the powder resistivity of the negative electrode active material at a pressure of 16 MPa is 5×10 -1 Ω·cm or less, and optionally 2×10 -1 Ω·cm. Thereby, the negative electrode active material has good conductivity, which is advantageous for improving the cycle performance and rate performance of the secondary battery.

[0037] The second aspect of the present application is a method for manufacturing a negative electrode active material, including: Step 1 of providing a carbon substrate with a graphitization degree of 87% or less, optionally 65% to 87%, and including a plurality of pore structures; and Step 2 of dispersing a filler in the pore structures of the carbon substrate to obtain a negative electrode active material. Here, the negative electrode active material includes a carbon substrate and a filler. The carbon substrate includes a plurality of pore structures, at least a part of the filler is located in the pore structures of the carbon substrate, the filler includes one or more of the elements capable of alloying reaction with Li, and optionally, the elements capable of alloying reaction with Li include one or more of silicon element, tin element, and germanium element, and provides a method for manufacturing a negative electrode active material.

[0038] In any embodiment of the present application, in Step 1, the carbon substrate is manufactured by a method of putting a carbon source including a plurality of pore structures into a high-temperature furnace, performing graphitization treatment at 1600°C to 2400°C in a protective gas atmosphere, and obtaining a carbon substrate after completion. Thereby, a carbon substrate with a graphitization degree of 87% or less, optionally 65% to 87%, and including a plurality of pore structures can be obtained.

[0039] In any embodiment of the present application, the heat preservation time of the graphitization treatment is 1 h to 12 h.

[0040] In any embodiment of the present application, the carbon source includes one or more selected from hard carbon, petroleum coke, pitch coke, biomass carbon, and resin carbon.

[0041] By performing graphitization treatment on a carbon source including a plurality of pore structures at a certain temperature, the micropores in the carbon source are reduced, while the uniformity of the subsequent dispersion of the filler is improved. At the same time, the excess chemical bonds on the surface of the carbon source are removed, the content of oxygen-containing functional groups in the carbon source is reduced, and the side reactions of the electrolyte can be reduced. Therefore, the initial Coulomb efficiency, conductivity, and high-temperature performance of the obtained carbon substrate can be improved, and the secondary battery can be given good cycle performance.

[0042] In any embodiment of the present application, in step 1, the initial Coulomb efficiency of the carbon matrix is 75% or more, and optionally 75% - 87%.

[0043] In any embodiment of the present application, in step 1, the powder resistivity of the carbon matrix at a pressure of 16 MPa is 5×10 -2 Ω·cm or less, and optionally 3.5×10 -2 Ω·cm or less.

[0044] In any embodiment of the present application, in step 1, the BET specific surface area of the carbon matrix is 50 m 2 / g - 1000 m 2 / g, and optionally 100 m 2 / g - 700 m 2 / g.

[0045] In any embodiment of the present application, in step 1, the volume particle size Dv50 of the carbon matrix is 3 μm - 50 μm, and optionally 5 μm - 20 μm.

[0046] In any embodiment of the present application, in step 2, the process of dispersing the filler in the pore structure of the carbon matrix includes a liquid phase deposition process and a vapor phase deposition process, and optionally, it is a vapor phase deposition process. Compared with the liquid phase deposition process, the vapor phase deposition process is advantageous for depositing the filler well in the pore structure of the carbon matrix and uniformly dispersing it, and can avoid the problems of filler aggregation and / or excessive deposition on the surface of the carbon substrate. Also, the vapor phase deposition process is mature and easy for industrial mass production.

[0047] In any embodiment of the present application, the vapor phase deposition process includes a chemical vapor deposition process and a physical vapor deposition process, and optionally it is a chemical vapor deposition process.

[0048] In any embodiment of the present application, in Step 2, the step of dispersing the filler in the pore structure of the carbon matrix includes putting the carbon matrix into a reactor, introducing a first mixed gas containing a source of an element capable of alloying reaction with Li, depositing at a first temperature T1 for a first time t1, and obtaining a negative electrode active material after completion.

[0049] In any embodiment of the present application, the first mixed gas includes a source of an element capable of alloying reaction with Li and a protective gas. Optionally, the volume occupancy of the source of the element capable of alloying reaction with Li in the first mixed gas is 10% - 50%.

[0050] In any embodiment of the present application, the first mixed gas further includes a carbon source gas.

[0051] In any embodiment of the present application, the volume ratio of the source of the element capable of alloying reaction with Li to the carbon source gas is 0.5:1 or more, and optionally (2 - 10):1.

[0052] In any embodiment of the present application, the volume occupancy of the carbon source gas in the first mixed gas is 20% or less, and optionally 5% - 20%.

[0053] In any embodiment of the present application, the pressure in the reactor is 200 Pa - 600 Pa higher than the atmospheric pressure.

[0054] In any embodiment of the present application, the total gas flow rate of the first mixed gas is 0.5 L / min - 20 L / min.

[0055] In any embodiment of the present application, the first temperature T1 is 400 °C - 1000 °C.

[0056] In any embodiment of the present application, the first time t1 is 1 h - 12 h.

[0057] By adjusting at least one of the composition ratio of the first air-fuel mixture, the total gas flow rate of the first air-fuel mixture, the first temperature, and the first time to be within the above range, it is advantageous for depositing a filler in the pore structure of the carbon substrate, and it is also advantageous for adjusting the crystallinity and / or crystal grain size of the filler to be within an appropriate range.

[0058] In any embodiment of the present application, the method further includes step 3 of forming a coating layer containing one or more of a carbon material, a conductive polymer, a metal oxide, and a metal sulfide on at least a part of the surface of the negative electrode active material obtained in step 2.

[0059] In any embodiment of the present application, the step of forming the coating layer includes putting the negative electrode active material obtained in step 2 into a reaction furnace, introducing a second air-fuel mixture containing a carbon source gas, depositing at a second temperature T2 for a second time t2, and obtaining a carbon-coated negative electrode active material after completion.

[0060] In any embodiment of the present application, the second air-fuel mixture includes a carbon source gas and a protective gas. Optionally, the volume occupancy ratio V2 of the carbon source gas in the second air-fuel mixture is 5% to 50%.

[0061] In any embodiment of the present application, the total gas flow rate of the second air-fuel mixture is 0.5 L / min to 20 L / min.

[0062] In any embodiment of the present application, the second temperature T2 is 700 °C to 850 °C.

[0063] In any embodiment of the present application, the second time t2 is 1 h to 6 h.

[0064] In step 3, by adjusting at least one of the composition ratio of the second air-fuel mixture, the total gas flow rate of the second air-fuel mixture, the second temperature, and the second time to be within the above range, it is advantageous for forming a coating layer with an appropriate thickness and avoiding the coating layer being too thick and reducing the specific capacity of the negative electrode active material.

[0065] The third aspect of the present application provides a secondary battery including a negative electrode sheet containing a negative electrode active material according to the first aspect of the present disclosure, or a negative electrode active material produced by the method according to the second aspect of the present application.

[0066] The fourth aspect of the present application provides an electric consumer device including the secondary battery according to the third aspect of the present application.

[0067] The inventors have found through research that by filling a filler having the advantage of high capacity into the pore structure of a carbon matrix having a low graphitization degree, the obtained negative electrode active material can have high capacity, high initial Coulomb efficiency, low volume expansion, high conductivity and good cycle stability, and at the same time, the secondary battery can have high energy density, high initial Coulomb efficiency and long cycle life. Since the electric consumer device of the present application includes the secondary battery according to the present application, it has at least the same advantages as the above secondary battery.

Brief Description of the Drawings

[0068] To more clearly explain the technical solutions of the embodiments of the present application, the following briefly introduces the drawings necessary for the embodiments of the present application. It is clear that the drawings described below are only some embodiments of the present application. Those skilled in the art can obtain other drawings based on these drawings without creative labor.

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Embodiments for Carrying Out the Invention

[0069] Hereinafter, embodiments specifically disclosing the negative electrode active material of the present application, a method for manufacturing the same, and a secondary battery and an electric consumption device including the same will be described in detail with appropriate reference to the drawings. However, detailed descriptions that are not necessary may be omitted. For example, detailed descriptions of known matters or redundant descriptions of substantially the same configurations may be omitted. This is to avoid making the following description unnecessary and redundant and to facilitate the understanding of those skilled in the art. It should be noted that the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0070] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit. A predetermined range is defined by selecting one lower limit and one upper limit, and the selected lower limit and upper limit limit the boundaries of a specific range. The range thus limited may be a range including the end values or not including the end values, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, when ranges of 60 to 120 and 80 to 110 are given for a specific parameter, ranges of 60 to 110 and 80 to 120 are also understood to be expected. Also, when the minimum range values 1 and 2 and the maximum range values 3, 4, and 5 are given, ranges of 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 may all be expected. In this application, unless otherwise explained, the numerical range "a~b" is an abbreviation indicating any combination of real numbers between a and b, and both a and b are real numbers. For example, the numerical range "0~5" indicates listing all real numbers between "0~5" in this specification, and "0~5" is an abbreviation for the combination of these numerical values. Also, when a certain parameter is expressed as an integer of 2 or more (≧2), it corresponds to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0071] Unless otherwise specified, all embodiments and selectable embodiments of this application may be combined with each other to form a new technical solution. Also, such a technical solution is considered to be included in the disclosure content of this application.

[0072] Unless otherwise specified, all technical features and selectable technical features of this application may be combined with each other to form a new technical solution. Also, such a technical solution is considered to be included in the disclosure content of this application.

[0073] Unless otherwise specified, all steps of the present application may be performed in order or randomly, but it is preferred to perform them in order. For example, the fact that the above method includes steps (a) and (b) means that the above method may include steps (a) and (b) performed in order, or may include steps (b) and (a) performed in order. For example, when it is mentioned that the above method may further include step (c), it means that step (c) may be added to the above method in any order. For example, the above method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), etc.

[0074] Unless otherwise specified, the terms "comprising" and "including" described in the present application are meant to be open-ended and may also be closed-ended. For example, the above "comprising" and "including" can represent further "comprising" or "including" other components not listed, or "comprising" or "including" only the components listed.

[0075] Unless otherwise specified, in the present application, the term "or" is inclusive. For example, the phrase "A or B" represents "A, B, or both A and B". More specifically, any of the following conditions is satisfied: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), or both A and B are true (or exist).

[0076] Unless otherwise specified, in the present application, relative terms such as "first" and "second" are used to distinguish different objects and do not necessarily represent a specific order or a primary-secondary relationship.

[0077] In the present application, the terms "a plurality", "a plurality of types", "several" mean two or more than two.

[0078] Unless otherwise specified, the terms used in the present application have the meanings known to those skilled in the art and are commonly understood.

[0079] Unless otherwise specified, the numerical values of each parameter mentioned in this application can be measured according to various commonly used test methods in this field, for example, the test methods described in this application.

[0080] To meet the high requirements for the energy density of secondary batteries, non-carbon-based materials such as silicon-based materials, tin-based materials, and germanium-based materials have attracted wide attention because they have a high theoretical specific capacity. The theoretical specific capacity of silicon is as high as 4200 mAh / g, the theoretical specific capacity of tin is as high as 994 mAh / g, and the theoretical specific capacity of germanium is as high as 1600 mAh / g. Therefore, the energy density of secondary batteries can be significantly improved.

[0081] However, different from the energy storage mechanism of graphite, non-carbon-based materials such as silicon-based materials, tin-based materials, and germanium-based materials store energy by generating an alloying reaction with metals (such as lithium, sodium, etc.) to form an alloy. Therefore, there is a huge volume effect in the charge and discharge process, which is likely to cause particle crushing and pulverization. Furthermore, a pulverization problem occurs in the negative electrode film layer, the electrical contact with the current collector is easily released, the desorption process of active ions does not proceed smoothly, and the irreversible capacity increases significantly. In addition, the huge volume effect may repeatedly cause the destruction and reconstruction of the solid electrolyte interface (SEI) film on the surface of the negative electrode active material particles, further increasing the irreversible consumption of active ions, ultimately affecting the capacity of the secondary battery. At the same time, as the charge and discharge process progresses, the SEI film on the surface of the negative electrode active material particles becomes thicker and thicker, thereby increasing the impedance of the secondary battery. In addition, the unstable SEI film on the surface of the negative electrode active material particles directly contacts the negative electrode active material and the electrolyte, further increasing the interfacial side reaction and irreversible capacity.

[0082] Therefore, when the non-carbon-based material is used as the negative electrode active material, generally, there are drawbacks such as a high irreversible capacity, a low initial Coulombic efficiency, and a large volume expansion. As a result, the actual capacity loss of the secondary battery increases, and the cycle life deteriorates. In addition, silicon is a semiconductor material with a low intrinsic conductivity and poor electrical conductivity, which may further deteriorate the electrochemical performance of the secondary battery.

[0083] In view of this, the inventors of the present application have proposed a novel negative electrode active material through extensive research. The negative electrode active material can have a high specific capacity, a high initial Coulombic efficiency, a low volume expansion, high electrical conductivity, and good cycle stability, and can endow the secondary battery with a high energy density, a high initial Coulombic efficiency, and a long cycle life. Negative electrode active material A first aspect of an embodiment of the present application provides a negative electrode active material. The negative electrode active material includes a carbon matrix having a graphitization degree of 87% or less and a plurality of pore structures, and a filler at least partially located in the pore structures of the carbon matrix and containing one or more of the elements capable of alloying reaction with Li.

[0084] By including one or more of the elements capable of alloying reaction with Li, the filler can contribute to a high capacity and compensate for the defect of the low capacity of the carbon matrix. However, due to a serious volume effect, it affects the performance of the electrochemical performance.

[0085] In the research of the prior art, in order to overcome the defect of large volume expansion of the filler, the currently adopted method is to install the filler on a carbon matrix or natural graphite containing a plurality of pore structures by processes such as deposition. However, the currently adopted carbon matrix containing a plurality of pore structures is obtained, for example, by etching and creating pores using a pore-forming agent of an alkaline solution. Since the carbon matrix itself is non-graphitizable carbon (or amorphous carbon), it has the disadvantages of high irreversible capacity, low initial Coulomb efficiency, and poor conductivity. Natural graphite itself has a pore structure and can also be used as a deposited substrate, and has the advantage of excellent conductivity. However, due to the irregular structure of natural graphite pores, the dispersion uniformity of the filler is poor. In addition, natural graphite also has the disadvantages of poor structural stability, large volume expansion, and poor cycle performance.

[0086] Therefore, the method used in the prior art cannot endow the obtained negative electrode active material with high specific capacity, high initial Coulomb efficiency, low volume expansion, high conductivity, and good cycle stability.

[0087] The inventors of the present invention have found through research that by providing a filler with a high specific capacity in the pore structure of a carbon matrix with a low degree of graphitization (exceeding 0 and not exceeding 87%), the obtained negative electrode active material can be endowed with high specific capacity, high initial Coulomb efficiency, low volume expansion, high conductivity, and good cycle stability. At the same time, the secondary battery can be endowed with high energy density, high initial Coulomb efficiency, and long cycle life. The degree of graphitization of the carbon matrix of the present application is not more than 87%, and it has the advantages of higher conductivity and higher initial Coulomb efficiency compared with the carbon matrix obtained by pore formation using the above-mentioned pore-forming agent. Compared with natural graphite, it has the advantages of smaller volume expansion and higher cycle stability. Therefore, the negative electrode active material according to the present application can fully exert the advantage of the high specific capacity of the filler and can compensate for the disadvantages of poor conductivity and low initial Coulomb efficiency of the filler. In addition, at least a part of the filler is located in the pore structure of the carbon matrix, so that the volume expansion of the filler can be reduced by the carbon matrix.

[0088] In the present application, the graphitization degree of the carbon matrix is 87% or less, and may be, for example, 85% or less, 80% or less, 75% or less, or 70% or less. When the graphitization degree of the carbon matrix exceeds 87%, the volume expansion of the carbon matrix during the charge and discharge process is large and the structural stability is poor, which affects the cycle stability and cycle life of the negative electrode active material. When the graphitization degree of the carbon matrix decreases, its structural stability improves, which is advantageous for improving the cycle stability of the negative electrode active material and extending the cycle life of the secondary battery.

[0089] The inventors of the present application further found through research that it is not preferable that the graphitization degree of the carbon matrix is too low. In this case, since the initial Coulomb efficiency and conductivity are poor, the improvement effect on the initial Coulomb efficiency and conductivity of the negative electrode active material becomes insignificant. For example, the graphitization degree of the carbon matrix may further be 10% or more, 20% or more, 30% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, or 65% or more.

[0090] In some embodiments, the graphitization degree of the carbon matrix may be 40% - 87%, 50% - 87%, 60% - 87%, 65% - 87%, 65% - 85%, 65% - 82%, or 65% - 80%. This is advantageous for the negative electrode active material to better combine high specific capacity, high initial Coulomb efficiency, low volume expansion, high conductivity, and good cycle stability.

[0091] In some embodiments, at least a part of the filler is located in the pore structure of the carbon matrix and has a gap between the filler and the carbon matrix. When there is a gap between the filler and the carbon matrix, this part of the gap can serve as a space to accommodate the volume expansion of the filler and relieve the stress generated during the expansion process of the filler, thereby further reducing the probability of particle crushing and pulverization.

[0092] In some embodiments, optionally, the element capable of alloying reaction with the Li includes one or more of a silicon element, a tin element, and a germanium element. This is advantageous for the negative electrode active material to have the advantage of a high specific capacity.

[0093] In some embodiments, the filler includes one or more of a silicon-based material, a tin-based material, and a germanium-based material, and optionally includes a silicon-based material.

[0094] In the present application, the term "silicon-based material" means a compound containing a silicon element. In some embodiments, the silicon-based material may include one or more of elemental silicon, silicon oxide, silicon carbon material, silicon nitride composite, and silicon alloy.

[0095] In the present application, the term "tin-based material" means a compound containing a tin element. In some embodiments, the tin-based material may include one or more of elemental tin, tin oxide, tin sulfide, tin phosphide, tin composite oxide, tin carbon material, and tin alloy material. The tin composite oxide refers to a material in which some glass-phase metals and / or non-metal oxides are introduced into tin oxide.

[0096] In the present application, the term "germanium-based material" means a compound containing a germanium element. In some embodiments, the germanium-based material may include one or more of elemental germanium, germanium oxide, germanium carbon material, germanium alloy material, and germanate.

[0097] In some embodiments, the filler may include a crystalline filler and / or an amorphous filler.

[0098] In some embodiments, the filler includes a crystalline silicon-based material and / or an amorphous silicon-based material. The silicon-based material has the advantage of high specific capacity and is beneficial for improving the energy density of the secondary battery. Optionally, the filler includes crystalline silicon alone and / or amorphous silicon alone.

[0099] In some embodiments, the crystal grain size of the crystalline filler is 100 nm or less, for example, it may be 80 nm or less, 70 nm or less, 60 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less. Optionally, the crystal grain size of the crystalline filler is 2 nm to 50 nm, 2 nm to 40 nm, 2 nm to 30 nm, or 2 nm to 20 nm.

[0100] When the crystal grain size of the crystalline filler is large, it is beneficial for improving the initial Coulomb efficiency of the secondary battery, but it is disadvantageous for the cycle performance and storage performance of the secondary battery. Therefore, when the crystalline filler has an appropriate crystal grain size, the initial Coulomb efficiency of the secondary battery can be improved, and it is possible to avoid having a great adverse effect on the cycle performance and storage performance of the secondary battery.

[0101] The crystal grain size of the crystalline filler has the meaning known in the art and can be measured by known devices and methods in the art. For example, tests and measurements can be performed using a High Resolution Transmission Electron Microscope (HRTEM).

[0102] In some embodiments, the filler can be obtained by a vapor deposition process. For example, the filler may include one or more of a vapor-deposited silicon-based material, a tin-based material, and a germanium-based material. Optionally, the filler includes a vapor-deposited silicon-based material. More optionally, the filler includes vapor-deposited silicon. The vapor deposition process includes a physical vapor deposition process and a chemical vapor deposition process. Optionally, it is a chemical vapor deposition process, for example, any one of a thermal chemical vapor deposition process, a plasma-enhanced chemical vapor deposition process, and a microwave plasma-enhanced chemical vapor deposition process. Compared with the liquid phase deposition process, the vapor deposition process is advantageous for well depositing the filler into the pore structure of the carbon matrix and uniformly dispersing it, and can avoid the problems of the filler aggregating and / or depositing in large amounts on the surface of the carbon substrate. Also, the vapor deposition process is mature and easy for industrial mass production.

[0103] In some embodiments, in the X-ray diffraction spectrum measured by an X-ray diffractometer for the negative electrode active material, the negative electrode active material includes a (002) crystal plane peak at 26.4° and a (111) crystal plane peak at 28.6°, and the ratio of the half-value width of the (002) crystal plane peak to the half-value width of the (111) crystal plane peak is 0.2 to 50, for example, a range consisting of any numerical value such as 0.2, 0.5, 1, 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or more. Optionally, the ratio of the half-value width of the (002) crystal plane peak to the half-value width of the (111) crystal plane peak is 0.2 to 20.

[0104] The half-value width of the (002) crystal plane peak and the half-value width of the (111) crystal plane peak are calculated by referring to JIS K0131-1996, using an X-ray diffractometer (for example, Bruker D8 Discover) to calculate the lattice constant of the crystal, searching for the peak by the centroid method to obtain the C 002 peak position and the Si 111 peak position of two parallel samples, and the test angle range may be 20° to 80°.

[0105] (002) The full width at half maximum (FWHM) of the (002) crystal plane peak can characterize the arrangement perfection of the (002) crystal plane in the carbon matrix, and the FWHM of the (111) crystal plane peak can characterize the content of silicon monomers and the crystal grain size of silicon monomers in the filler. By controlling that the FWHM of the (002) crystal plane peak and the FWHM of the (111) crystal plane peak are within an appropriate range, the carbon matrix has an appropriate graphitization degree, and the filler has an appropriate crystal grain size. Therefore, it is advantageous for the negative electrode active material to have high specific capacity, high initial Coulomb efficiency, low volume expansion, high conductivity, and good cycle stability.

[0106] In some embodiments, the negative electrode active material further includes a coating layer located on at least a part of the surface of the carbon matrix. Since the coating layer can prevent the filler and the electrolyte from directly contacting each other, it can reduce side reactions of the electrolyte, reduce the consumption of active ions, improve the cycle performance of the secondary battery, and improve the stability of the negative electrode slurry, avoiding the increase in the processing difficulty of the negative electrode slurry caused by the reaction of the filler with solvent water or the like. In addition, the coating layer also plays a role in alleviating the volume expansion of the filler, which is also advantageous for improving the structural stability of the negative electrode active material and the electrochemical performance of the secondary battery.

[0107] In some embodiments, optionally, the coating layer includes one or more of a carbon material, a conductive polymer, a metal oxide, and a metal sulfide.

[0108] In some embodiments, the carbon material includes one or more of hard carbon, soft carbon, graphene, carbon fiber, and carbon nanotube.

[0109] In some embodiments, the conductive polymer includes one or more of polyaniline, polypyrrole, and polythiophene.

[0110] In some embodiments, the metal oxide includes one or more of iron oxide, zinc oxide, tin oxide, copper oxide, and titanium oxide.

[0111] In some embodiments, the metal sulfide includes one or more of tin sulfide, molybdenum sulfide, titanium sulfide, iron sulfide, and copper sulfide.

[0112] In some embodiments, the coating layer includes a carbon material. Thereby, in addition to preventing the filler and the electrolyte from directly contacting each other and buffering the volume expansion of the filler, the coating layer can also provide a part of the capacity to increase the specific capacity of the negative electrode active material. Further, when the coating layer includes a carbon material, it also contributes to improving the conductivity of the filler, particularly the silicon-based material, and is further advantageous for improving the capacity of the negative electrode active material.

[0113] In some embodiments, the thickness of the coating layer is 100 nm or less, and optionally 10 nm to 100 nm. When the thickness of the coating layer is within the above range, the integrity of the coating layer is higher, and it is possible to more effectively avoid the contact between the filler and the electrolyte, so as to reduce the side reaction of the electrolyte and make the negative electrode active material have a high specific capacity, a high initial Coulomb efficiency, and a low volume expansion, which is advantageous. Although the integrity of the coating layer is better when its thickness is greater than 100 nm, the brittleness increases, so in the process of repeated charge and discharge, crushing and pulverization are more likely to occur, and the specific capacity of the negative electrode active material is also decreased.

[0114] In some embodiments, the negative electrode active material includes a carbon element and an element capable of alloying reaction with Li.

[0115] In some embodiments, the mass percentage of the carbon element in the negative electrode active material is 20 wt% to 80 wt%, for example, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, or a range consisting of any of these numerical values. Optionally, the mass percentage of the carbon element in the negative electrode active material is 30 wt% to 70 wt%. The distribution region of the carbon element is not specifically limited. For example, it may be located in at least one of the carbon matrix, the filler, and the coating layer.

[0116] In some embodiments, the mass percentage of the element capable of alloying reaction with Li in the negative electrode active material is 20 wt% to 80 wt%, for example, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 70 wt%, 75 wt%, 80 wt%, or a range consisting of any of these numerical values. Optionally, the mass percentage of the element capable of alloying reaction with Li in the negative electrode active material is 30 wt% to 70 wt%. Optionally, the element capable of alloying reaction with Li includes a silicon element.

[0117] When the content of the carbon element and / or the element capable of alloying reaction with Li in the negative electrode active material is within the above range, it is advantageous for the negative electrode active material to have both high specific capacity and high conductivity.

[0118] In some embodiments, the negative electrode active material further includes other elements in addition to the carbon element and the element capable of alloying reaction with Li. The other elements include one or more of an oxygen element, a metal element, and a nitrogen element. The distribution region of the other elements is not specifically limited. For example, it may be located in at least one of the coating layer, the filler, and the carbon matrix.

[0119] In some embodiments, optionally, the total mass percentage of the other elements in the negative electrode active material is 20 wt% or less, more optionally 10 wt% or less, and 5 wt% or less.

[0120] In some embodiments, the initial Coulombic efficiency of the carbon matrix is 75% or more, and optionally 75% to 87%. This is advantageous for improving the initial Coulombic efficiency of the negative electrode active material.

[0121] In some embodiments, the powder resistivity of the carbon matrix at a pressure of 16 MPa is 5×10 -2 Ω·cm or less, and optionally 3.5×10 -2 Ω·cm or less. This is advantageous for improving the conductivity of the negative electrode active material.

[0122] In some embodiments, the BET specific surface area of the carbon matrix is 50 m 2 / g to 1000 m 2 / g, and optionally 100 m 2 / g to 700 m 2 / g. This is advantageous for the negative electrode active material to have an appropriate BET specific surface area, so that the surface activity of the negative electrode active material can be reduced, the interfacial side reactions can be decreased, the film formation consumption of the SEI film can be reduced, and furthermore, the initial Coulombic efficiency and cycle performance of the secondary battery can be improved.

[0123] In some embodiments, the graphitization degree of the negative electrode active material is 65% or more, and optionally 65% to 87%. This is advantageous for the negative electrode active material to better have high initial Coulombic efficiency, high conductivity and good cycle stability.

[0124] In some embodiments, the initial Coulombic efficiency of the negative electrode active material is 92% or more, and optionally 92% to 95%. This can reduce the irreversible consumption of active ions and improve the capacity performance and cycle performance of the secondary battery.

[0125] In some embodiments, the volume particle size Dv50 of the negative electrode active material is 3 μm to 50 μm, and optionally 5 μm to 20 μm.

[0126] In some embodiments, the volume particle size Dv90 of the negative electrode active material is 60 μm or less, and optionally 20 μm to 50 μm.

[0127] In some embodiments, the particle size distribution width (Dv90 - Dv10) / Dv50 of the negative electrode active material is 1.0 to 3.0, and optionally 1.0 to 2.0.

[0128] When at least one of the volume particle size Dv50, the volume particle size Dv90, and the particle size distribution width (Dv90 - Dv10) / Dv50 of the negative electrode active material is within the above range, it contributes to the reduction of the surface activity of the negative electrode active material, the reduction of the interfacial side reaction, and the reduction of the film formation consumption of the SEI film. Furthermore, it is also advantageous for improving the active ion and electron transmission performance, and can further improve the cycle performance of the secondary battery.

[0129] In some embodiments, the BET specific surface area of the negative electrode active material is 2 m 2 / g to 100 m 2 / g, and optionally 2 m 2 / g to 30 m 2 / g, or 2 m 2 / g to 20 m 2 / g. When the BET specific surface area of the negative electrode active material is within the above range, it contributes to the reduction of the interfacial activity, the reduction of the interfacial side reaction, and the reduction of the film formation consumption of the SEI film. Thereby, the initial Coulomb efficiency and cycle performance of the secondary battery can be improved.

[0130] In some embodiments, the powder resistivity of the negative electrode active material at a pressure of 16 MPa is 5×10 -1 Ω·cm or less, and optionally 2×10 -1 Ω·cm. Thereby, since the negative electrode active material has good conductivity, it is advantageous for improving the cycle performance and rate performance of the secondary battery.

[0131] In this application, the volume particle diameters Dv10, Dv50, and Dv90 of the material (e.g., negative electrode active material, carbon matrix, etc.) have the known meanings in this field, indicating the particle diameters corresponding to when the cumulative percentage based on the volume of the material reaches 10%, 50%, and 90% respectively, and can be measured by the known equipment and methods in this field. For example, referring to GB / T 19077-2016, it can be easily measured using a laser particle size analyzer. The test equipment may be a Mastersizer 3000 type laser particle size analyzer from Malvern Panalytical Ltd., UK.

[0132] In this application, the BET specific surface area of the material (e.g., negative electrode active material, carbon matrix, etc.) has the known meaning in this field and can be measured by the known equipment and methods in this field. For example, referring to GB / T 19587-2017, the nitrogen gas adsorption specific surface area analysis test method is adopted for testing and can be calculated by the BET (Brunauer Emmett Teller) method. The nitrogen gas adsorption specific surface area analysis test can be carried out by a specific surface area and porosity analyzer of the TRISTAR II 3020 type from Micromeritics, USA.

[0133] In this application, the powder resistivity of the material (e.g., negative electrode active material, carbon matrix, etc.) has the known meaning in this field and can be measured by the known equipment and methods in this field. For example, a certain mass of powder sample can be put into the sample cup of a resistivity tester, and after applying a certain pressure, data can be artificially collected, and the test results of the powder resistivity at different pressures of the sample can be recorded. In this application, the test pressure may be 16 MPa.

[0134] In this application, the graphitization degree of the material (e.g., negative electrode active material, carbon matrix, etc.) has the known meaning in this field and can be measured by the known equipment and methods in this field. For example, referring to JISK 0131-1996, after obtaining the interplanar spacing d of the (002) crystal plane using an X-ray diffractometer (Bruker D8 Discover) 002 we get, the formula g = (0.3440 - d 002The graphitization degree of the material is calculated based on [[ID=]] / (0.3440 - 0.3354)×100%.

[0135] In the present application, the content of each element in the negative electrode active material can be measured by known devices and methods in this field. For example, the content of carbon element can be measured with reference to GB / T 20123 - 2006 / ISO 15350:2000, and the test device may be an HCS - 140 type infrared carbon and sulfur analyzer. The content of silicon element may be measured with reference to GB / T 20975.5 - 2020. The content of tin element in the negative electrode active material may be measured with reference to GB / T 20975.10 - 2020. The content of germanium element may be measured with reference to GB / T 20127.6 - 2006. Manufacturing method

[0136] The second aspect of the embodiment of the present application provides a method for manufacturing a negative electrode active material that can manufacture the negative electrode active material according to the first aspect of the present application.

[0137] The method includes step 1 of providing a carbon matrix with a graphitization degree of 87% or less, optionally 65% - 87%, and including a plurality of pore structures, and step 2 of dispersing a filler in the pore structures of the carbon matrix to obtain a negative electrode active material. Here, the negative electrode active material includes a carbon matrix and a filler. The carbon matrix includes a plurality of pore structures. At least a part of the filler is located in the pore structures of the carbon matrix. The filler includes one or more of the elements capable of alloying reaction with Li. Optionally, the elements capable of alloying reaction with Li include one or more of silicon element, tin element, and germanium element.

[0138] In some embodiments, in step 1, the carbon substrate is manufactured by a method in which a carbon source containing a plurality of pore structures is placed in a high-temperature furnace and graphitized at 1600°C to 2400°C in a protective gas atmosphere, and after completion, a carbon substrate is obtained. For example, graphitization treatment may be performed within a range consisting of any value such as 1600°C, 1700°C, 1800°C, 1900°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, or higher. Thereby, a carbon substrate with a graphitization degree of 87% or less, optionally 65% to 87%, and having a plurality of pore structures can be obtained.

[0139] If the graphitization temperature is too low, the obtained carbon substrate is still non-graphitizable carbon (or amorphous carbon), its irreversible capacity is high, the initial Coulomb efficiency is low, and its conductivity is poor. As a result, the initial Coulomb efficiency and cycle performance of the secondary battery are affected. If the graphitization temperature is too high, the volume expansion during the charge and discharge process of the obtained carbon substrate is large, and the structural stability is poor. As a result, the cycle stability of the negative electrode active material and the cycle performance of the secondary battery are affected.

[0140] In some embodiments, optionally, the heating rate of the high-temperature furnace is 10°C / min or less, for example 8°C / min or less, 5°C / min or less.

[0141] In some embodiments, optionally, the heat preservation time of the graphitization treatment is 1h to 12h, for example, it may be within a range consisting of any value such as 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h or higher.

[0142] In some embodiments, optionally, the carbon source includes one or more of hard carbon, petroleum coke, pitch coke, biomass carbon, and resin carbon.

[0143] In some embodiments, optionally, the high-temperature furnace may be any one of graphitization furnaces such as box-type graphitization furnace, Acheson-type graphitization furnace, continuous graphitization furnace, and Lengthwise Graphitization Furnace.

[0144] In Step 1, there are many types of carbon sources for manufacturing the carbon matrix, with large natural reserves, low cost, and a simple manufacturing process for the carbon matrix. The carbon source containing the plurality of pore structures may be directly commercially available or may be manufactured according to known methods in the art. For example, it can be obtained by etching and creating pores using a pore-forming agent in an alkaline solution.

[0145] By graphitizing the carbon source containing the plurality of pore structures at a certain temperature, the micropores in the carbon source are reduced, while the uniformity of the dispersion of the subsequent filler is improved. At the same time, the excess chemical bonds on the surface of the carbon source are removed, the content of oxygen-containing functional groups in the carbon source is reduced, and side reactions of the electrolyte can be reduced. Therefore, the initial Coulomb efficiency, conductivity, and high-temperature performance of the obtained carbon matrix can be improved, and the secondary battery can be given good cycle performance.

[0146] In some embodiments, in Step 1, the initial Coulomb efficiency of the carbon matrix is 75% or more, and optionally, it is 75% - 87%.

[0147] In some embodiments, in Step 1, the powder resistivity of the carbon matrix at a pressure of 16 MPa is 5×10 -2 Ω·cm or less, and optionally, it is 3.5×10 -2 Ω·cm or less.

[0148] In some embodiments, in Step 1, the BET specific surface area of the carbon matrix is 50 m 2 / g - 1000 m 2 / g, and optionally, it is 100 m 2 / g - 700 m 2 / g.

[0149] In some embodiments, in step 1, the volume particle size Dv50 of the carbon matrix is 3 μm to 50 μm, and optionally 5 μm to 20 μm.

[0150] In some embodiments, in step 2, the process of dispersing the filler in the pore structure of the carbon matrix includes a liquid phase deposition process and a vapor phase deposition process, and optionally, it is a vapor phase deposition process. Compared with the liquid phase deposition process, the vapor phase deposition process is advantageous for depositing the filler well in the pore structure of the carbon matrix and uniformly dispersing it, and can avoid the problem of filler aggregation and / or the problem of a large amount of deposition on the surface of the carbon substrate. In addition, the vapor phase deposition process is mature and easy for industrial mass production.

[0151] In some embodiments, optionally, the vapor phase deposition process includes a chemical vapor deposition process and a physical vapor deposition process, and more optionally, it is a chemical vapor deposition process, for example, any one of a thermal chemical vapor deposition process, a plasma enhanced chemical vapor deposition process, and a microwave plasma enhanced chemical vapor deposition process may be used.

[0152] In some embodiments, in step 2, the step of dispersing the filler in the pore structure of the carbon matrix includes putting the carbon matrix into a reaction furnace, introducing a first mixed gas containing a source of an element capable of alloying with Li, depositing at a first temperature T1 for a first time t1, and obtaining a negative electrode active material after completion.

[0153] In some embodiments, optionally, the first mixed gas includes a source of an element capable of alloying with Li and a protective gas.

[0154] In some embodiments, optionally, the volume occupancy rate of the source of the element capable of alloying with Li in the first mixed gas is 10% to 50%, for example, it may be in the range consisting of any value such as 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% or more.

[0155] In some embodiments, the first mixture gas may further contain a carbon source gas.

[0156] In some embodiments, optionally, the volume ratio of the source of an element capable of alloying reaction with the Li to the carbon source gas is 0.5:1 or more, and optionally (2-10):1. When the volume ratio of the source of an element capable of alloying reaction with the Li to the carbon source gas is within the above range, it is advantageous for the negative electrode active material to have a high specific capacity. When the volume ratio of the two is too small, the carbon element content in the obtained filler becomes high, and the content of the element capable of alloying reaction with Li becomes low, and as a result, the improvement effect of the negative electrode active material capacity becomes insignificant.

[0157] In some embodiments, optionally, the volume occupancy rate of the carbon source gas in the first mixture gas is 20% or less, and more optionally 5%-20%. In this case, it is advantageous for the negative electrode active material to have both a high specific capacity and high conductivity.

[0158] In some embodiments, optionally, the volume occupancy rate of the protective gas in the first mixture gas is 30%-90%, for example, a range consisting of any value such as 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or more.

[0159] In some embodiments, the total gas flow rate of the first mixture gas may be 0.5 L / min-20 L / min. For example, a range consisting of any value such as 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min, 12 L / min, 14 L / min, 16 L / min, 18 L / min, 20 L / min, or more.

[0160] In some embodiments, the pressure inside the reactor may be a micro positive pressure. For example, it may be 200 Pa to 600 Pa higher than the atmospheric pressure, which is advantageous for the deposition process to proceed smoothly.

[0161] In some embodiments, the reactor includes, but is not limited to, any one of a growth furnace, a rotary kiln, a tubular furnace, and a fluidized bed.

[0162] In some embodiments, the first temperature T1 may be 400°C to 1000°C. For example, it may be 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, or a range consisting of any of the above numerical values.

[0163] In some embodiments, the first time t1 may be 1 h to 12 h. For example, it may be 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, or a range consisting of any of the above arbitrary numerical values.

[0164] In the vapor deposition process, by adjusting at least one of the composition ratio of the first mixed gas, the total gas flow rate of the first mixed gas, the first temperature, and the first time within the above ranges, it is advantageous for depositing a filler on the pore structure of the carbon matrix, and it is also advantageous for adjusting the crystallinity and / or crystal grain size of the filler within an appropriate range.

[0165] In some embodiments, the method further includes step 3 of forming a coating layer containing one or more of a carbon material, a conductive polymer, a metal oxide, and a metal sulfide on at least a part of the surface of the negative electrode active material obtained in step 2.

[0166] The method for forming a coating layer on the surface of at least a part of the negative electrode active material obtained in Step 2 is not particularly limited and can be selected according to the composition of the coating layer. For example, any of solid-phase coating, liquid-phase coating, or gas-phase coating may be employed.

[0167] In some embodiments, the step of forming the coating layer includes the step of obtaining the coating layer after mixing the negative electrode active material obtained in Step 2 with a coating material and then performing carbonization treatment. Optionally, the coating material includes one or more of pitch (e.g., coal pitch, petroleum pitch, etc.) and polymer materials. Optionally, the temperature of the carbonization treatment is 500°C to 1000°C.

[0168] In some embodiments, the step of forming the coating layer includes the step of putting the negative electrode active material obtained in Step 2 into a reaction furnace, introducing a second mixed gas containing a carbon source gas, depositing for a second time t2 at a second temperature T2, and obtaining a negative electrode active material coated with carbon after completion.

[0169] In some embodiments, the second mixed gas includes a carbon source gas and a protective gas. Optionally, the volume occupancy ratio V2 of the carbon source gas in the second mixed gas is 5% to 50%, for example, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or any range consisting of the above arbitrary numerical values.

[0170] In some embodiments, the total gas flow rate of the second mixed gas is 0.5 L / min to 20 L / min. For example, 0.8 L / min, 1 L / min, 2 L / min, 3 L / min, 4 L / min, 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min, 12 L / min, 14 L / min, 16 L / min, 18 L / min, 20 L / min, or any range consisting of the above arbitrary numerical values.

[0171] In some embodiments, the second temperature T2 is from 700°C to 850°C. For example, it may be 700°C, 710°C, 720°C, 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, 800°C, 810°C, 820°C, 830°C, 840°C, 850°C or a range consisting of any of the above values.

[0172] In some embodiments, the second time t2 is from 1 h to 6 h. For example, it may be 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h or a range consisting of any of the above values.

[0173] In step 3, by adjusting at least one of the composition ratio of the second air-fuel mixture, the total gas flow rate of the second air-fuel mixture, the second temperature, and the second time to be within the above ranges, it is advantageous for forming a coating layer with an appropriate thickness, and it is avoided that the coating layer is too thick and reduces the specific capacity of the negative electrode active material.

[0174] In the present application, the term "protective gas" includes one or more of nitrogen gas and noble gases. Optionally, the noble gas may include one or more of argon gas, helium gas, etc.

[0175] In the present application, the term "source of an element capable of alloying reaction with Li" means a gas capable of forming the filler of the present application. For example, it may include one or more of a silicon source gas, a tin source gas, and a germanium source gas.

[0176] The silicon source gas is a gas capable of forming the silicon-based material of the present application. Optionally, the silicon source gas is monosilane (H4Si), disilane (H6Si2), trisilane (H8Si3), tetrachlorosilane (Cl4Si), trichlorosilane (Cl3HSi), dichlorosilane (Cl2H2Si), monochlorosilane (ClH3Si), silicon tetrafluoride (F4Si), trifluorosilane (F3HSi), difluorosilane (F2H2Si), monofluorosilane (FH3Si), hexachlorodisilane (Cl6Si2), pentachlorodisilane (Cl5HSi2), tetrachlorodisilane (Cl4H2Si2 (including 1,1,2,2-tetrachlorodisilane and 1,1,1,2-tetrachlorodisilane)), trichlorodisilane (Cl3H3Si2 (including 1,1,2-trichlorodisilane and 1,1,1-trichlorodisilane)), dichlorodisilane (Cl2H4Si2 (including 1,1-dichlorodisilane and 1,2-dichlorodisilane)), monochlorodisilane (ClH5Si2), hexafluorodisilane (F6Si2), pentafluorodisilane (F5HSi2), 1,1,2,2-tetrafluorodisilane (F4H2Si2), 1,1,1-trifluorodisilane (F3H3Si2), difluorodisilane (F2H4Si2 (including 1,1-difluorodisilane and 1,2-difluorodisilane)), monofluorodisilane (FH5Si2), methylsilane, ethylsilane, dimethylsilane, trimethylsilane, tetramethylsilane, methyldisilane, dimethyldisilane, trimethyldisilane, tetramethyldisilane, hexamethylsilane, methyltrichlorosilane, methylchlorosilane, chloroethylsilane, dichlorodimethylsilane, and dichlorodiethylsilane, and may include one or more of them.

[0177] The tin source gas is a gas capable of forming the tin-based material of the present application. Optionally, the tin source gas includes, but is not limited to, one or more of stannane (H4Sn), Cl4Sn, Cl3HSn, Cl2H2Sn, ClH3Sn, F4Sn, F3HSn, F2H2Sn, and FH3Sn.

[0178] The germanium source gas is a gas that can form the germanium-based material of the present application. Optionally, the germanium source gas includes, but is not limited to, one or more of monogerman (H4Ge), Cl4Ge, and F4Ge.

[0179] In the present application, the "carbon source gas" means a gas that can form a carbon material. Optionally, the carbon source gas includes, but is not limited to, one or more of methane, ethane, propane, isopropane, butane, isobutane, ethylene, propylene, butene, acetylene, chloroethane, fluoroethane, difluoroethane, chloromethane, fluoromethane, difluoromethane, trifluoromethane, vinyl chloride, fluoroethylene, difluoroethylene, methylamine, formaldehyde, benzene, toluene, xylene, styrene, and phenol.

[0180] Unless otherwise specified, each raw material and its equipment used in the manufacturing method of the present application can all be obtained commercially. Secondary battery

[0181] The third aspect of the embodiment of the present application provides a secondary battery.

[0182] The secondary battery mentioned in the examples or embodiments of the present application is a single physical module that includes one or more battery cells and provides a higher voltage and capacity. For example, the secondary battery mentioned in the present application may include battery cells, battery modules, or battery packs, etc. A battery cell is the smallest unit that constitutes a secondary battery and can perform the functions of charging and discharging independently. The shape of the battery cell of the present application is not particularly limited and may be cylindrical, rectangular, or any other shape. Figure 1 shows a rectangular-structured battery cell 5 as an example.

[0183] In some embodiments, the battery cell includes an electrode assembly, and the cell may further include an exterior package. The electrode assembly is made from a positive electrode sheet, a negative electrode sheet, a separator, etc. by a winding process and / or a lamination process, and the exterior package can be used to package the above electrode assembly. The exterior package may be a hard case such as a hard plastic case, an aluminum case, a steel case, etc. The exterior package may also be a soft package such as a bag package. The material of the soft package may be plastic, for example, one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0184] In some embodiments, as shown in FIG. 2, the exterior package can include a housing 51 and a cover plate 53. The housing 51 includes a bottom plate and side plates connected to the bottom plate, and the bottom plate and the side plates enclose to form a receiving chamber. The housing 51 has an opening communicating with the receiving chamber, and the cover plate 53 covers the opening so as to seal the receiving chamber. The electrode assembly 52 is packaged in the receiving chamber. The number of the electrode assemblies 52 included in the battery cell 5 may be one or more, and may be adjusted according to requirements.

[0185] In some embodiments of the present application, the battery cell may be assembled as a battery module. The number of battery cells included in the battery module may be plural, and the specific number may be adjusted according to the use and capacity of the battery module. FIG. 3 is a schematic diagram of a battery module 4 as an example. As shown in FIG. 3, in the battery module 4, a plurality of battery cells 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Further, the plurality of battery cells 5 may be fixed by fasteners.

[0186] Optionally, the battery module 4 further includes a housing having a receiving space, and the plurality of battery cells 5 are received in the receiving space.

[0187] In some embodiments, the battery module may be assembled as a battery pack, and the quantity of battery modules included in the battery pack may be adjusted according to the use and capacity of the battery pack. FIGS. 4 and 5 are schematic diagrams of a battery pack 1 as an example. As shown in FIGS. 4 and 5, the battery pack 1 may include a battery case and a plurality of battery modules 4 provided in the battery case. The battery case includes an upper case 2 and a lower case 3, and the upper case 2 is provided to cover the lower case 3 and forms a sealed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery case in any manner.

[0188] The present application is not particularly limited to the type of secondary battery. For example, the secondary battery includes, but is not limited to, lithium-ion batteries, sodium-ion batteries, etc. [Negative electrode sheet]

[0189] In some embodiments, 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 and containing a negative electrode active material. For example, the negative electrode current collector has two surfaces facing each other in its thickness direction, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0190] In some embodiments, the negative electrode film layer includes a negative electrode active material according to the first aspect of the embodiment of the present application or a negative electrode active material manufactured by the method described in the second aspect of the embodiment of the present application. Thereby, a secondary battery can be provided with high energy density, high initial coulombic efficiency, and long cycle life. In some embodiments, the negative electrode film layer may further include other negative electrode active materials other than the negative electrode active material. In some embodiments, the other negative electrode active materials include, but are not limited to, one or more of natural graphite, artificial graphite, soft carbon, hard carbon, silicon monomer, silicon oxide, silicon nitride composite, silicon alloy material, tin monomer, tin oxide, tin alloy material, and lithium titanate. The present application is not limited to these materials, and other conventionally known materials used as negative electrode active materials of secondary batteries may also be used.

[0191] In some embodiments, optionally, the negative electrode film layer may further include a negative electrode conductive agent. In the present application, the type of the negative electrode conductive agent is not particularly limited. By way of example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0192] In some embodiments, the negative electrode film layer may further include a negative electrode adhesive. In the present application, the type of the negative electrode adhesive is not particularly limited. By way of example, the negative electrode adhesive may include one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (for example, polyacrylic acid PAA, polymethacrylic acid PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0193] In some embodiments, the negative electrode film layer may further contain other auxiliaries. For example, the other auxiliaries may include thickeners such as sodium carboxymethyl cellulose (CMC-Na), PTC thermistor materials, etc.

[0194] In some embodiments, the negative electrode current collector may employ a metal foil sheet or a composite current collector. As an example of the metal foil sheet, a copper foil can be used. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. For example, the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0195] The negative electrode film layer is generally formed by applying a negative electrode slurry to a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is generally formed by dispersing a negative electrode active material, an optional conductive agent, an optional adhesive, and other optional auxiliaries in a solvent and uniformly stirring. The solvent may be N-methylpyrrolidone (NMP) or deionized water, but is not limited thereto.

[0196] The negative electrode sheet does not exclude other additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet according to the present application may further include a conductive primer layer (for example, including a conductive agent and an adhesive) provided on the surface of the negative electrode current collector and sandwiched between the negative electrode current collector and the negative electrode film layer. In some embodiments, the negative electrode sheet according to the present application may further include a protective layer covering the surface of the negative electrode film layer. [Positive Electrode Sheet]

[0197] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector and containing a positive electrode active material. For example, the positive electrode current collector has two surfaces facing each other in its thickness direction, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0198] The positive electrode film layer contains a positive electrode active material, and the positive electrode active material may adopt a positive electrode active material used in known secondary batteries in this field.

[0199] When the secondary battery of the present application is a lithium-ion battery, the positive electrode active material may include one or more of lithium transition metal oxides, lithium-containing phosphates having an olivine structure, and modified compounds thereof. Examples of lithium transition metal oxides may include lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and one or more of modified compounds thereof. Examples of lithium-containing phosphates having an olivine structure may include lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and one or more of modified compounds thereof. The present application is not limited to these materials, and other conventionally known materials used as positive electrode active materials for secondary batteries may also be used.

[0200] In some embodiments, in order to further increase the energy density of the secondary battery, the positive electrode active material used in the lithium-ion battery has a general formula of Li a Ni b Co c M d O e A fIt may contain one or more of the lithium transition metal oxides and their modified compounds thereof. 0.8 ≦ a ≦ 1.2, 0.5 ≦ b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M contains one or more selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti and B, and A contains one or more selected from N, F, S and Cl.

[0201] For example, the positive electrode active material used in a lithium ion battery may contain one or more of LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi 0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), LiNi 0.85 Co 0.15 Al 0.05 O2, LiFePO4 and LiMnPO4 may contain one or more of them.

[0202] When the secondary battery of the present application is a sodium ion battery, the positive electrode active material may contain one or more of a sodium-containing transition metal oxide, a polyanion material (for example, phosphate, fluorophosphate, pyrophosphate, sulfate, etc.), and a Prussian blue-based material, but is not limited thereto.

[0203] For example, the positive electrode active material used in a sodium ion battery may be NaFeO2, NaCoO2, NaCrO2, NaMnO2, NaNiO2, NaNi 1 / 2 Ti 1 / 2 O2, NaNi 1 / 2 Mn 1 / 2 O2, Na 2 / 3 Fe 1 / 3 Mn 2 / 3 O2, NaNi 1 / 3 Co1 / 3 Mn 1 / 3 O2, NaFePO4, NaMnPO4, NaCoPO4, Prussian blue-based materials, and one or more of the materials having the general formula X p M’ q (PO4) r O x Y 3-x and may contain one or more of them. In the general formula X p M’ q (PO4) r O x Y 3-x , 0 < p ≤ 4, 0 < q ≤ 2, 1 ≤ r ≤ 3, 0 ≤ x ≤ 2, X includes one or more of H + , Li + , Na + , K + and NH4 + , M’ is a transition metal cation and optionally one or more of V, Ti, Mn, Fe, Co, Ni, Cu, and Zn, and Y is a halogen anion and optionally one or more of F, Cl, and Br.

[0204] In the present application, the modified compound of each of the above cathode active materials may be obtained by performing doping modification and / or surface coating modification on the cathode active material.

[0205] In some embodiments, optionally, the cathode film layer may further contain a cathode conductive agent. In the present application, the type of the cathode conductive agent is not particularly limited. For example, the cathode conductive agent includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0206] In some embodiments, optionally, the positive electrode film layer may further include a positive electrode adhesive. In the present application, the type of the positive electrode adhesive is not particularly limited. For example, the positive electrode adhesive may include one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a terpolymer of vinylidene fluoride - tetrafluoroethylene - propylene, a terpolymer of vinylidene fluoride - hexafluoropropylene - tetrafluoroethylene, a copolymer of tetrafluoroethylene - hexafluoropropylene, and a fluorine - containing acrylate - based resin.

[0207] In some embodiments, the positive electrode current collector may employ a metal foil sheet or a composite current collector. As an example of the metal foil sheet, an aluminum foil may be employed. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. For example, the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0208] The positive electrode film layer is generally formed by applying a positive electrode slurry to a positive electrode current collector, drying, and cold pressing. The positive electrode slurry is generally formed by dispersing a positive electrode active material, an optional conductive agent, an optional adhesive, and any other components in a solvent and stirring uniformly. The solvent may be N - methylpyrrolidone (NMP), but is not limited thereto. [Electrolyte]

[0209] The electrolyte plays a role in conducting active ions between the positive electrode sheet and the negative electrode sheet. In the present application, the type of the electrolyte is not particularly limited and can be selected according to requirements. For example, the electrolyte may include one or more types selected from solid electrolytes and liquid electrolytes (i.e., electrolytic solutions).

[0210] In some embodiments, the electrolyte employs an electrolytic solution, and the electrolytic solution includes an electrolyte salt and a solvent.

[0211] When the secondary battery of the present application is a lithium-ion battery, by way of example, the electrolyte salt may include one or more types of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoro(oxalato)borate (LiDFOB), lithium bis(oxalato)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluoro(dioxalato)phosphate (LiDFOP), lithium tetrafluoro(oxalato)phosphate (LiTFOP).

[0212] When the secondary battery of the present application is a sodium ion battery, particularly a sodium ion secondary battery, the electrolyte salt may include one or more of sodium hexafluorophosphate (NaPF6), sodium tetrafluoroborate (NaBF4), sodium perchlorate (NaClO4), sodium hexafluoroarsenate (NaAsF6), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium trifluoromethanesulfonate (NaTFS), sodium difluoroborate (NaDFOB), sodium diborate (NaBOB), sodium difluorophosphate (NaPO2F2), sodium difluorodiphosphate (NaDFOP), and sodium tetrafluorophosphate (NaTFOP).

[0213] The type of the solvent is not particularly limited and can be selected according to actual requirements. In some embodiments, by way of example, the solvent may include one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0214] In some embodiments, the electrolyte may further contain additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve some performance of the battery, such as additives for improving the overcharging performance of the battery, additives for improving the high-temperature performance of the battery, and additives for improving the low-temperature power performance of the battery. [Separator]

[0215] In a secondary battery using an electrolyte or a secondary battery using a solid electrolyte, a separator is also included. The separator is provided between the positive electrode sheet and the negative electrode sheet, mainly serves to prevent short circuit between the positive electrode and the negative electrode, and can allow active ions to pass through. In the present application, the type of the separator is not particularly limited, and any known porous separation membrane having good chemical stability and mechanical stability can be selected.

[0216] In some embodiments, the material of the separator may include one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multi-layer composite film. When the separator is a multi-layer composite film, the materials of each layer may be the same or different. [Manufacturing method]

[0217] The manufacturing method of the secondary battery of the present application is known. In some embodiments, a secondary battery can be formed by assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. As an example, a positive electrode sheet, a separator, and a negative electrode sheet are formed into an electrode assembly by a winding process or a lamination process, the electrode assembly is placed in an exterior package, dried, and then an electrolyte is injected, and through processes such as vacuum encapsulation, standing, formation, and shaping, a battery cell can be obtained. A plurality of battery cells may further form a battery module in series, parallel, or series-parallel. A plurality of battery modules may form a battery pack in series, parallel, or series-parallel. In some embodiments, a plurality of battery cells may directly form a battery pack. Electricity consumption device

[0218] Embodiments of the present application further provide an electrical consumption device including the secondary battery of the present application. The secondary battery may be used as a power source for the electrical consumption device or as an energy storage means for the electrical consumption device. The electrical consumption device may be a mobile device (such as a mobile phone, a tablet computer, a notebook computer, etc.), an electric vehicle (such as a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), a train, a ship, a satellite, an energy storage system, etc., but is not limited thereto.

[0219] The electrical consumption device may select a specific type of secondary battery, such as a battery cell, a battery module, or a battery pack, etc., according to requirements.

[0220] FIG. 6 is a schematic diagram of an electrical consumption device as an example. This electrical consumption device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. In order to meet the requirements for high power and high energy density of this electrical consumption device, a battery pack or a battery module may be adopted as a power source.

[0221] As another example, the electrical consumption device may be a mobile phone, a tablet computer, a notebook computer, etc. Generally, this electrical consumption device is required to be thin, and a battery cell may be adopted as a power source. Example

[0222] The following examples illustrate the disclosure of the present application in more detail. However, these examples are merely illustrative, and it is obvious to those skilled in the art that various modifications and changes can be made within the scope of the disclosure of the present application. All parts, percentages, and ratios described in the following examples are based on mass unless otherwise specified. All reagents used in the examples are commercially available or may be synthesized according to conventional methods, and can be used as they are without further treatment. Also, all devices used in the examples are commercially available. Example 1 (1) Manufacture of negative electrode active material

[0223] Step 1: Put 1 kg of commercially available porous biomass carbon (BET surface area is 1545 m 2 / g, volume particle size Dv50 is about 6 μm, and it may be obtained by pore formation of a pore-forming agent) into a graphitization furnace, heat it up to 2400 °C at a rate of 5 °C / min under nitrogen gas protection for graphitization treatment, keep it at 2400 °C for 2 h, and after completion, cool it to room temperature to obtain a carbon matrix with a graphitization degree of 87%, an initial Coulomb efficiency of 85%, a powder resistivity of 5.5×10 -3 Ω·cm, and a BET specific surface area of 100 m 2 / g.

[0224] Step 2: Put the above carbon matrix into a vapor deposition furnace, heat it up to 500 °C at a rate of 5 °C / min, introduce a first mixed gas of 20% monosilane + 80% nitrogen gas (volume ratio), the total gas flow rate is 5 L / min, the pressure in the reaction furnace is 200 Pa higher than the atmospheric pressure, and the deposition reaction is 8 h.

[0225] Step 3: Stop the introduction of the first mixed gas, further heat it up to 800 °C at a rate of 5 °C / min, introduce a second mixed gas of 40% acetylene + 60% nitrogen gas (volume ratio), set the total gas flow rate to 0.8 L / min, conduct a deposition reaction for 2 h, cool it after completion, discharge it, and pass through a 325-mesh sieve to obtain a negative electrode active material. (2) Manufacture of secondary battery (full cell)

[0226] Manufacture of the negative electrode sheet: The negative electrode active material manufactured above, the conductive carbon black and carbon nanotubes as conductive agents, and polyacrylic acid as an adhesive were uniformly mixed at a mass ratio of 95:1.9:0.1:3, and then added to deionized water as a solvent. Stir until the system becomes uniform under the action of a high-speed stirrer to obtain a negative electrode slurry with a solid content of 45%. The negative electrode slurry is uniformly coated on a copper foil, which is a negative electrode current collector, dried at 85°C, and cold-pressed to obtain a negative electrode sheet.

[0227] Manufacture of the positive electrode sheet: LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), carbon black (Super P) as a conductive agent, and polyvinylidene fluoride (PVDF) as an adhesive were sufficiently stirred and mixed in an appropriate amount of solvent NMP at a mass ratio of 97:1:2 to form a uniform positive electrode slurry. The positive electrode slurry was uniformly coated on the surface of an aluminum foil, which is a positive electrode current collector, dried, and cold-pressed to obtain a positive electrode sheet.

[0228] Manufacture of the electrolyte: Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were uniformly mixed at a volume ratio of 20:20:60 to form an organic solvent. Then, LiPF6 was dissolved in the above organic solvent, and fluoroethylene carbonate (FEC) was added. The concentration of LiPF6 in the electrolyte is 1 mol / L, and the mass percentage of FEC is 5 wt%.

[0229] Manufacture of the separator: Celgard 2400 separator is used.

[0230] Manufacture of the secondary battery: The positive electrode sheet, separator, and negative electrode sheet were stacked and wound in sequence to obtain an electrode assembly. The electrode assembly was placed in an outer package, dried, and then the electrolyte was injected. After passing through processes such as vacuum encapsulation, standing, formation, and shaping, a secondary battery was obtained. (3) Manufacture of a coin cell (half cell)

[0231] The manufactured negative electrode active material above, conductive carbon black as a conductive agent, and polyacrylic acid as an adhesive were uniformly mixed at a mass ratio of 8:1:1, then added to deionized water as a solvent, and stirred by the action of a high-speed stirrer until the system became uniform, obtaining a negative electrode slurry with a solid content of 45%. The negative electrode slurry was uniformly coated on a copper foil as a negative electrode current collector, dried at 85 °C, and cold-pressed to obtain an electrode sheet. Using a metallic lithium sheet as the counter electrode and a Celgard 2400 separator, an electrolytic solution similar to that during the manufacture of the above secondary battery was injected and assembled to obtain a coin cell. Example 2-24

[0232] The manufacturing methods of the secondary battery and the coin cell are similar to those of Example 1, and the difference is that the parameters of the manufacturing process of the negative electrode active material were adjusted. Specifically, refer to Table 1A and Table 1B. Comparative Example 1

[0233] The manufacturing methods of the secondary battery and the coin cell are similar to those of Example 1, and the difference is that crystalline silicon coated with amorphous carbon was adopted as the negative electrode active material, and the thickness of the coating layer is 80 nm.

[0234] Step 1: Provide crystalline silicon particles with a volume particle size Dv50 of 500 nm.

[0235] Step 2: Put the above crystalline silicon particles into a rotary kiln, introduce a mixed gas of 40% acetylene + 60% nitrogen gas (by volume ratio), set the total gas flow rate to 0.8 L / min, carry out a deposition reaction at 800 °C for 2 h, cool down after completion, discharge, and obtain a crystalline silicon material coated with amorphous carbon. Comparative Example 2

[0236] The manufacturing methods of the secondary battery and the coin cell are similar to those of Example 1, and the difference is that the parameters of the manufacturing process of the negative electrode active material were adjusted.

[0237] Step 1: Mechanically pulverize, classify, spheroidize, and purify flaky graphite to obtain natural spherical graphite.

[0238] Step 2: Put 1 kg of natural spherical graphite into a vapor deposition furnace, heat it up to 500 °C at a rate of 5 °C / min, introduce the first mixed gas with 20% monosilane + 80% nitrogen gas (volume ratio), the total gas flow rate is 5 L / min, the pressure in the reaction furnace is 200 Pa higher than the atmospheric pressure, and carry out the deposition reaction for 8 h.

[0239] Step 3: Stop introducing the first mixed gas, further heat it up to 800 °C at a rate of 5 °C / min, introduce the second mixed gas with 40% acetylene + 60% nitrogen gas (volume ratio), set the total gas flow rate to 0.8 L / min, carry out the deposition reaction for 2 h, cool it down and discharge it after completion, and pass through a 325-mesh sieve to obtain the negative electrode active material. Comparative Example 3

[0240] The manufacturing method of the secondary battery and the coin cell is similar to that of Example 1, and the difference is that the parameters of the manufacturing process of the negative electrode active material are adjusted. Specifically, refer to Table 1A and Table 1B. Comparative Example 4

[0241] The manufacturing method of the secondary battery and the coin cell is similar to that of Example 1, and the difference is that the parameters of the manufacturing process of the negative electrode active material are adjusted.

[0242] Step 1: Select 1 kg of porous biomass carbon and use it directly as the carbon substrate without graphitization treatment.

[0243] Step 2: Put the above carbon substrate into a vapor deposition furnace, heat it up to 500 °C at a rate of 5 °C / min, introduce the first mixed gas with 20% monosilane + 80% nitrogen gas (volume ratio), the total gas flow rate is 5 L / min, the pressure in the reaction furnace is 200 Pa higher than the atmospheric pressure, and carry out the deposition reaction for 8.

[0244] Step 3: Stop introducing the first mixed gas, further heat it up to 800 °C at a rate of 5 °C / min, introduce the second mixed gas with 40% acetylene + 60% nitrogen gas (volume ratio), set the total gas flow rate to 0.8 L / min, carry out the deposition reaction for 2 h, cool it down and discharge it after completion, and pass through a 325-mesh sieve to obtain the negative electrode active material. Test section (1) Test on the graphitization degree of the carbon matrix and the negative electrode active material

[0245] Referring to JIS K 0131-1996, using an X-ray diffractometer, the interplanar spacing d of the (002) crystal plane 002 was obtained, and then, based on the formula g = (0.3440 - d 002 ) / (0.3440 - 0.3354) × 100%, the graphitization degrees of the carbon matrix and the negative electrode active material were calculated. As the test equipment, a Bruker D8 Discover X-ray diffractometer can be used. (2) First Coulomb efficiency test of the carbon matrix

[0246] The carbon matrix manufactured above, conductive carbon black as the conductive agent, and polyacrylic acid as the adhesive were uniformly mixed at a mass ratio of 8:1:1, then added to deionized water as the solvent, and stirred by the action of a high-speed stirrer until the system became uniform to obtain a negative electrode slurry with a solid content of 45%. The negative electrode slurry was uniformly coated on a copper foil as the negative electrode current collector, dried at 85°C, and cold-pressed to obtain an electrode sheet. Using a lithium metal piece as the counter electrode and a Celgard 2400 separator, the same electrolyte as in Example 1 above was injected and assembled to obtain a coin cell.

[0247] After the coin cell was left standing for 4 h, it was placed in a Land Battery Test System, discharged to 5 mV at a constant current of 0.05C, left standing for 10 min, then discharged to 5 mV at a constant current of 50 μA, and the total discharge capacity of the coin cell was recorded. After the coin cell was left standing for 10 min, it was charged to 2.0V at a constant current of 0.1C, and the charge capacity of the coin cell was recorded. The first Coulomb efficiency of the carbon matrix = charge capacity / total discharge capacity. (3) Test on the powder resistivity of the carbon matrix and the negative electrode active material

[0248] Put a carbon matrix of fixed mass and a sample of negative electrode active material powder into the sample cup of a resistivity tester. After applying a certain pressure, artificially collect data and record the test results of the powder resistivity of the sample at different pressures. In this application, the test pressure may be 16 MPa. (4) Test of specific surface area of carbon matrix

[0249] Referring to GB / T 19587-2017, the nitrogen gas adsorption specific surface area analysis test method was adopted for testing, and the specific surface area of the carbon matrix was calculated by the BET (Brunauer Emmett Teller) method. The test equipment can adopt the TRISTAR II 3020 type specific surface area and porosity analyzer of Micromeritics, USA. (5) Test of crystal grain size of filler

[0250] After cutting out a sample from the middle region of the negative electrode active material particles using a Dual Beam Focused Ion Beam - Transmission Electron Microscope (Dual Beam FIB-SEM), the crystal grain size of the filler is tested by a High Resolution Transmission Electron Microscope (HRTEM). (6) Test of content of each element in negative electrode active material

[0251] Referring to GB / T 20123-2006 / ISO 15350:2000, measure the carbon element content in the negative electrode active material, and the measuring instrument may be an HCS-140 type infrared carbon and sulfur analyzer. Referring to GB / T 20975.5-2020, measure the silicon element content in the negative electrode active material. Referring to GB / T 20975.10-2020, measure the tin element content in the negative electrode active material. Referring to GB / T 20127.6-2006, measure the germanium element content in the negative electrode active material. (7) Test of X-ray diffraction spectrum of negative electrode active material

[0252] With reference to JIS K 0131-1996, the lattice constant of the crystal was calculated using an X-ray diffractometer, and the C 002 peak position and Si 111 peak position of two parallel samples were obtained using the centroid method. The test angle range may be 20° to 80°. From the X-ray diffraction spectrum of the negative electrode active material, the half-value widths of the (002) crystal plane peak at 26.4° and the (111) crystal plane peak at 28.6° can be obtained. As the test equipment, a Bruker D8 Discover X-ray diffractometer can be used. (8) Test of the initial Coulomb efficiency of the negative electrode active material

[0253] After the coin cells manufactured in the above examples and comparative examples were allowed to stand for 4 h, they were placed in a land battery tester and discharged to 5 mV at a constant current of 0.05C. After standing for 10 min, they were discharged to 5 mV at a constant current of 50 μA, and the total discharge capacity of the coin cells was recorded as the lithium insertion capacity. Then, after the coin cells were allowed to stand for 10 min, they were charged to 2V at a constant current of 0.1C, and the charging capacity of the coin cells was recorded as the lithium desorption capacity. The initial Coulomb efficiency of the negative electrode active material = lithium desorption capacity / lithium insertion capacity. (9) Test of the cycle performance of the secondary battery

[0254] At 25°C, after the secondary battery manufactured above was fully charged at 0.5C (100% SOC), it was fully discharged at 1C, and this was regarded as one cycle charge-discharge process. The discharge capacity at this time was recorded as the initial discharge capacity. The secondary battery was subjected to a cycle charge-discharge test according to the above method, and the discharge capacity after each cycle was recorded until the discharge capacity of the secondary battery decayed to 80% of the initial discharge capacity. The cycle performance of the secondary battery was characterized by the number of cycles at this time. The higher the number of cycles of the secondary battery, the better the cycle performance.

[0255]

Table 1A

Table 1B

[0256] Summarizing the test results in Table 2, for the pore structure of a carbon matrix with a graphitization degree of 87% or less, for example, a filler having the advantage of a high specific capacity such as a silicon-based material, a tin-based material, or a germanium-based material is provided, and the obtained negative electrode active material can achieve both a high specific capacity, a high initial Coulomb efficiency, a high conductivity, and good cycle stability. Furthermore, it was found that the secondary battery can have a high energy density, a high initial Coulomb efficiency, and a long cycle life. Summarizing the test results of Examples 1 to 7, when the graphitization degree of the carbon matrix is 65% to 87%, the conductivity of the manufactured negative electrode active material is better, and the initial Coulomb efficiency is higher, reaching 92% or more. Also, it was found that the secondary battery also has a longer cycle life.

[0257] In the negative electrode active material according to the present application, at least a part of the filler is located in the pore structure of the carbon matrix, so that the volume expansion of the filler can also be reduced by the carbon matrix. Comparative Example 1 adopted crystalline silicon coated with carbon as the negative electrode active material. Since crystalline silicon has a huge volume effect, the carbon layer on the surface has a limited protective effect on crystalline silicon, and after multiple charge and discharge cycles, the carbon layer ruptures, and further, the destruction and reconstruction of the SEI film are repeated, increasing the irreversible consumption of active ions. Also, as the number of charge and discharge cycles increases, the thickness of the SEI film continues to increase, and further, the impedance of the secondary battery also increases. Therefore, the secondary battery manufactured in Comparative Example 1 has poor cycle performance.

[0258] Comparative Example 2 adopted natural spherical graphite as the carbon matrix. Natural spherical graphite itself has a pore structure and can be used as a deposited base, and has the advantage of excellent conductivity. However, the pore structure of natural spherical graphite is irregular, which deteriorates the dispersion uniformity of the filler. Furthermore, natural spherical graphite also has defects of poor structural stability and large volume expansion, which deteriorates the cycle performance of the secondary battery and cannot endow the secondary battery with a high energy density, a high initial Coulomb efficiency, and a long cycle life.

[0259] In Comparative Example 3, when the temperature during the graphitization treatment of the porous biomass carbon in Step 1 is higher than 2400°C, the graphitization degree of the resulting carbon matrix is too high. Therefore, the negative electrode active material produced at this time has a large volume expansion and poor structural stability during the charge and discharge process. As a result, the cycle performance of the secondary battery deteriorates, and it is impossible to endow the secondary battery with high energy density, high initial Coulomb efficiency, and long cycle life.

[0260] In Comparative Example 4, as-received porous biomass carbon that has not been graphitized is directly adopted as the carbon matrix. In this case, the carbon matrix is non-graphitizable carbon, which has the disadvantages of high irreversible capacity, low initial Coulomb efficiency, and poor conductivity. Therefore, the negative electrode active material produced therefrom has a low initial Coulomb efficiency and poor conductivity. As a result, it is impossible to endow the secondary battery with high energy density, high initial Coulomb efficiency, and long cycle life.

[0261] It should be noted that the present application is not limited to the above embodiments. The above embodiments are merely illustrative, and any configuration that has substantially the same technical idea and the same operation and effect within the technical scope of the present application is included in the technical scope of the present application. Also, within the scope not departing from the gist of the present application, various modifications that can be conceived by those skilled in the art to the embodiments, and other forms constructed by combining some components in the embodiments are also included in the scope of the present application.

[0262]

Table 2A

Table 2B

Claims

1. A negative electrode active material comprising a carbon matrix and a filler, wherein the graphitization degree of the carbon matrix is 87% or less, optionally 65% to 87%, the carbon matrix includes a plurality of pore structures, at least a part of the filler is located in the pore structure of the carbon matrix, and the filler contains one or more of the elements capable of alloying reaction with Li, and optionally, the elements capable of alloying reaction with Li include one or more of silicon element, tin element and germanium element, Negative electrode active material.

2. The filler includes one or more of a silicon-based material, a tin-based material and a germanium-based material, Optionally, the silicon-based material includes one or more of silicon single substance, silicon oxide, silicon carbon material, silicon nitride composite and silicon alloy, Optionally, the tin-based material includes one or more of tin single substance, tin oxide, tin sulfide, tin phosphide, tin composite oxide, tin carbon material and tin alloy material, Optionally, the germanium-based material includes one or more of germanium single substance, germanium oxide, germanium carbon material, germanium alloy material and germanium acid salt, The negative electrode active material according to Claim 1.

3. The filler includes a crystalline filler and / or an amorphous filler, and optionally includes a crystalline silicon-based material and / or an amorphous silicon-based material, Optionally, the crystal grain size of the crystalline filler is 100 nm or less, optionally 2 nm to 50 nm, The negative electrode active material according to Claim 1 or 2.

4. The filler contains one or more of a vapor-deposited silicon-based material, a tin-based material, and a germanium-based material, and optionally contains a vapor-deposited silicon-based material. The negative electrode active material according to any one of claims 1 to 3.

5. In the X-ray diffraction spectrum measured by an X-ray diffractometer, the negative electrode active material includes a (002) crystal plane peak at 26.4° and a (111) crystal plane peak at 28.6°, and the ratio of the half-value width of the (002) crystal plane peak to the half-value width of the (111) crystal plane peak is 0.2 to 50, and optionally 0.2 to 20. The negative electrode active material according to any one of claims 1 to 4.

6. At least a part of the filler is located in the pore structure of the carbon matrix, and There is a gap between the filler and the carbon matrix. The negative electrode active material according to any one of claims 1 to 5.

7. The negative electrode active material further includes a coating layer located on at least a part of the surface of the carbon matrix. Optionally, the coating layer includes one or more of a carbon material, a conductive polymer, a metal oxide, and a metal sulfide, and more optionally includes a carbon material. Optionally, the thickness of the coating layer is 100 nm or less, and more optionally 10 nm to 100 nm. The negative electrode active material according to any one of claims 1 to 6.

8. The negative electrode active material includes a carbon element and an element capable of alloying reaction with Li. Optionally, the mass percentage of the carbon element in the negative electrode active material is 20 wt% to 80 wt%, and more optionally 30 wt% to 70 wt%. Optionally, the mass percentage of the element capable of alloying reaction with Li in the negative electrode active material is 20 wt% to 80 wt%, and more optionally 30 wt% to 70 wt%. The negative electrode active material according to any one of claims 1 to 7.

9. The negative electrode active material further contains other elements, and the other elements include one or more of an oxygen element, a metal element, and a nitrogen element. Optionally, the total mass percentage of the other elements in the negative electrode active material is 20 wt% or less, and more optionally, 10 wt% or less. The negative electrode active material according to claim 8.

10. The carbon matrix satisfies at least one of the following: (1) The initial coulombic efficiency of the carbon matrix is 75% or more, and optionally 75% to 87%; (2) The powder resistivity of the carbon matrix at a pressure of 16 MPa is 5×10 －２ Ω·cm or less, and optionally 3.5×10 －２ Ω·cm or less; (3) The BET specific surface area of the carbon matrix is 50 m ２ / g to 1000 m ２ / g, and optionally 100 m ２ / g to 700 m ２ / g; The negative electrode active material according to any one of claims 1 to 9.

11. The negative electrode active material satisfies at least one of the following: (1) The graphitization degree of the negative electrode active material is 65% or more, and optionally 65% to 87%; (2) The initial coulombic efficiency of the negative electrode active material is 92% or more, and optionally 92% to 95%; (3) The volume particle size Dv50 of the negative electrode active material is 3 μm to 50 μm, and optionally 5 μm to 20 μm; (4) The volume particle size Dv90 of the negative electrode active material is 60 μm or less, and optionally 20 μm to 50 μm; (5) The particle size distribution width (Dv90 - Dv10) / Dv50 of the negative electrode active material is 1.0 to 3.0, and optionally 1.0 to 2.0; (6) The BET specific surface area of the negative electrode active material is 2 m ２ / g to 100 m ２ / g, and optionally 2 m ２ / g to 30 m ２ / g; (7) The powder resistivity of the negative electrode active material at a pressure of 16 MPa is 5×10 －１ Ω·cm or less, and optionally 2×10 －１ Ω·cm or less; The negative electrode active material according to any one of claims 1 to 10.

12. A method for manufacturing a negative electrode active material, Step 1 of providing a carbon substrate having a graphitization degree of 87% or less, optionally 65% to 87%, and including a plurality of pore structures, Step 2 of dispersing a filler in the pore structure of the carbon substrate to obtain a negative electrode active material, The negative electrode active material includes a carbon substrate and a filler. The carbon substrate includes a plurality of pore structures. At least a part of the filler is located in the pore structure of the carbon substrate. The filler includes one or more of the elements capable of alloying reaction with Li. Optionally, the elements capable of alloying reaction with Li include one or more of silicon element, tin element, and germanium element. A method for manufacturing a negative electrode active material.

13. In Step 1, the carbon substrate is manufactured by a method of putting a carbon source including a plurality of pore structures into a high-temperature furnace, performing graphitization treatment at 1600°C to 2400°C in a protective gas atmosphere, and obtaining a carbon substrate after completion. Optionally, the heat preservation time of the graphitization treatment is 1 h to 12 h. Optionally, the carbon source includes one or more selected from hard carbon, petroleum coke, pitch coke, biomass carbon, and resin carbon. The method according to claim 12.

14. In Step 1, the carbon substrate satisfies at least one of the following: (1) The initial Coulomb efficiency of the carbon matrix is 75% or more, and optionally 75% - 87%; (2) The powder resistivity of the carbon matrix at a pressure of 16 MPa is 5×10 －２ Ω·cm or less, and optionally 3.5×10 －２ Ω·cm or less; (3) The BET specific surface area of the carbon matrix is 50 m ２ / g - 1000 m ２ / g, and optionally 100 m ２ / g - 700 m ２ / g; (4) The volume particle size Dv50 of the carbon matrix is 3 μm - 50 μm, and optionally 5 μm - 20 μm; The method according to claim 12 or 13.

15. In step 2, the step of dispersing the filler in the pore structure of the carbon matrix includes a liquid phase deposition process and a gas phase deposition process, and optionally a gas phase deposition process, Optionally, the gas phase deposition process includes a chemical vapor deposition process and a physical vapor deposition process, and more optionally a chemical vapor deposition process, The method according to any one of claims 12 - 14.

16. In step 2, the step of dispersing the filler in the pore structure of the carbon matrix includes putting the carbon matrix into a reactor, introducing a first mixed gas containing a source of an element capable of alloying reaction with Li, and depositing at a first temperature T １ for a first time t １ to obtain a negative electrode active material after completion, Optionally, the first mixed gas includes a source of an element capable of alloying reaction with Li and a protective gas, and more optionally, the volume occupancy rate of the source of the element capable of alloying reaction with Li in the first mixed gas is 10% - 50%, Optionally, the pressure in the reactor is 200 Pa - 600 Pa higher than the atmospheric pressure, Optionally, the total gas flow rate of the first mixed gas is 0.5 L / min - 20 L / min, Optionally, the first temperature T １ is from 400 °C to 1000 °C, Optionally, the first time t １ is from 1 h to 12 h, The method according to claim 15.

17. The first air-fuel mixture further contains a carbon source gas, Optionally, the volume ratio of the source of the element capable of alloying reaction with the Li to the carbon source gas is 0.5:1 or more, and optionally, (2 to 10):1, Optionally, the volume occupancy rate of the carbon source gas in the first air-fuel mixture is 20% or less, and more optionally 5% to 20%, The method according to claim 16.

18. Further comprising step 3 of forming a coating layer containing one or more of a carbon material, a conductive polymer, a metal oxide, and a metal sulfide on at least a part of the surface of the negative electrode active material obtained in step 2, The method according to any one of claims 12 to 17.

19. Put the negative electrode active material obtained in step 2 into a reaction furnace, introduce a second air-fuel mixture containing a carbon source gas, and at a second temperature T ２ deposit for a second time t ２ to obtain a carbon-coated negative electrode active material after completion, Optionally, the second air-fuel mixture contains a carbon source gas and a protective gas, and more optionally, the volume occupancy rate V of the carbon source gas in the second air-fuel mixture ２ is 5% to 50%, Optionally, the total gas flow rate of the second air-fuel mixture is 0.5 L / min to 20 L / min, Optionally, the second temperature T ２ is 700 °C to 850 °C, Optionally, the second time t ２ is 1 h to 6 h, The method according to claim 18.

20. A secondary battery including a negative electrode sheet, wherein the negative electrode sheet contains the negative electrode active material according to any one of claims 1 to 11 or the negative electrode active material produced by the method according to any one of claims 12 to 19, a secondary battery.

21. An electric consumption device including the secondary battery according to claim 20.

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