Negative electrode material, method for producing the same, and lithium ion battery

Abstract

The present application relates to a negative electrode material, a method for manufacturing the same, and a lithium ion battery. By observing the SEM image, the negative electrode material includes carbonaceous particles having holes, and the aspect ratio of at least a part of the holes is greater than 3. When randomly observing 100 holes in total, the ratio of the number of holes having a hole diameter of 0.1 μm to 0.5 μm to the total number of holes is 60% or more, and the maximum hole diameter of the holes is 3 μm or less. The fact that the negative electrode material of the present application has elongated holes and the hole diameters of most of the holes are relatively small indicates that the internal hole volume of the carbonaceous particles of the present application is small and the number of macro holes is relatively small. Thereby, the carbonaceous particles have excellent compactness, thereby improving the capacity performance, expansion performance and cycle performance of the negative electrode material. 【Selected Drawing 2】

Description

Technical Field

[0001] <Cross - reference to Related Applications> This application claims the priority of a Chinese patent application filed with the National Intellectual Property Administration on June 30, 2023, with the application number 202310798360X and the application title "Negative Electrode Material and Its Manufacturing Method, Lithium - Ion Battery", and all of its content is incorporated herein by reference.

[0002] This application relates to the technical field of negative electrode materials, and particularly to negative electrode materials and their manufacturing methods, and lithium - ion batteries.

Background Art

[0003] With the progress of global warming, the control of CO2 emissions has become a major issue that allows no delay for human society. Against the backdrop of the country's "carbon neutrality" and "carbon peak", the development of new energy vehicles is an irresistible trend. Governments of various countries have successively introduced various preferential policies and subsidies to promote the development of new energy vehicles. Under the promotion of policies, electric vehicles powered by lithium - ion batteries are developing rapidly. The negative electrode material is an important component of the lithium - ion battery and directly determines the performance and price of the power battery.

[0004] At present, graphite is still the main material of the negative electrode material. Depending on the different sources, graphite can be divided into artificial graphite and natural graphite. Here, artificial graphite occupies most of the power battery market due to its good cycle stability. In the manufacturing process of artificial graphite, not only is a costly graphitization process required, but also the raw material prices have been continuously rising. The price of artificial graphite is not likely to decrease but will continue to rise. In order to further reduce the cost of the negative electrode material, people have turned their attention to natural graphite again. The greatest advantage of natural graphite is that there is no graphitization process in the manufacturing process and the price is low. However, in power batteries, its cycle stability and swelling performance are relatively poor.

[0005] Therefore, how to improve the expansion performance and cycle stability of natural graphite has become an important research topic in the current field of anode materials. Generally, natural graphite anode materials are produced from natural flake graphite raw materials through a spheroidization and modification process. In the production process of natural graphite anode materials, the spheroidization process inevitably generates internal voids in the particles. Generally, the internal voids in spherical natural graphite particles are relatively large, mostly on the micron order. The existence of these internal voids leads to the problems of large expansion and poor cycle stability of natural graphite anode materials. Generally, the expansion performance and cycle performance of the material are improved by reducing the size of the internal voids. However, in the actual production process, it is difficult to reduce the internal voids in graphite particles during the spheroidization process. Reducing the internal voids in particles in the subsequent process of spheroidization, and since some of the voids in spherical natural graphite particles are closed holes, it is not easy to control the degree of densification of the internal voids of the particles through a general filling process. Moreover, a phase different from the crystal structure of the original natural flake graphite material is introduced into the interior of the graphite particles after filling, increasing the grain boundaries and reducing the kinetic performance, and the electrochemical performance of the natural graphite anode material cannot be improved overall.

Summary of the Invention

Problems to be Solved by the Invention

[0006] This application provides an anode material, a method for manufacturing the same, and a lithium-ion battery, which can improve the capacity performance, expansion performance, and cycle performance of the anode material.

Means for Solving the Problems

[0007] According to a first aspect, an embodiment of this application provides an anode material. By observing the SEM image, the anode material includes carbonaceous particles having holes, and the aspect ratio of at least some of the holes is greater than 3. When randomly observing 100 holes in total, the proportion of the number of holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is 60% or more.

[0008] In some embodiments, the maximum hole diameter of the holes is 3 μm or less.

[0009] In some embodiments, the carbonaceous particles include natural graphite.

[0010] In some embodiments, the natural graphite includes at least one of flake graphite and microcrystalline graphite.

[0011] In some embodiments, the median diameter of the carbonaceous particles is 5 μm to 25 μm.

[0012] In some embodiments, the negative electrode material further includes a coating layer covering at least a part of the surface of the carbonaceous particles.

[0013] In some embodiments, the material of the coating layer includes a carbon material.

[0014] In some embodiments, the carbon material includes at least one of soft carbon, crystalline carbon, amorphous carbon, and hard carbon.

[0015] In some embodiments, the median diameter D50 of the negative electrode material satisfies 5 μm < D50 < 25 μm.

[0016] In some embodiments, the sphericity of the negative electrode material is Sh(10%) ≥ 0.75.

[0017] In some embodiments, the sphericity of the negative electrode material is Sh(50%) ≥ 0.83.

[0018] In some embodiments, the sphericity of the negative electrode material is Sh(90%) ≥ 0.88.

[0019] In some embodiments, the pore volume of the negative electrode material is 0.05 mL / g to 0.11 mL / g.

[0020] In some embodiments, the specific surface area of the negative electrode material is 0.5 m 2 / g to 3.5 m2 is / g.

[0021] According to a second aspect, an embodiment of the present application provides a method for manufacturing a negative electrode material, the method comprising: providing a natural graphite precursor, wherein the median diameter of the natural graphite precursor is 5 μm to 25 μm, the sphericity of the natural graphite precursor is Sh(10%) ≥ 0.75, the sphericity of the natural graphite precursor is Sh(50%) ≥ 0.83, and the sphericity of the natural graphite precursor is Sh(90%) ≥ 0.88; densifying the natural graphite precursor so that the obtained negative electrode material contains carbonaceous particles having holes, the aspect ratio of at least some of the holes being greater than 3, and when randomly observing 100 holes in total, the proportion of the holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is 60% or more.

[0022] In some embodiments, the natural graphite precursor is manufactured by a method of shaping natural graphite.

[0023] In some embodiments, the natural graphite includes at least one of flake graphite and microcrystalline graphite.

[0024] In some embodiments, the densifying treatment includes at least one of cold isostatic pressing, hot isostatic pressing, pressing, and hot press forming.

[0025] In some embodiments, the pressure of the densifying treatment is 20 MPa to 200 MPa.

[0026] In some embodiments, the time of the densifying treatment is 1 min to 200 min.

[0027] In some embodiments, the temperature of the densifying treatment is 25 °C to 1500 °C.

[0028] In some embodiments, before densifying the natural graphite precursor, the method further includes a step of mixing a coating material with the natural graphite precursor, and further densifying the mixture. The coating material includes at least one of a polymer, a resin, coal pitch, petroleum pitch, mesophase pitch, coal tar, and heavy oil.

[0029] In some embodiments, after obtaining the negative electrode material, the method further includes a step of mixing the negative electrode material with a coating material and then performing a heat treatment.

[0030] In some embodiments, the coating material includes at least one of a polymer, a resin, coal pitch, petroleum pitch, mesophase pitch, coal tar, and heavy oil.

[0031] In some embodiments, the mass ratio of the negative electrode material to the coating material is 100:(2 - 100).

[0032] In some embodiments, the temperature of the heat treatment is 800°C to 3000°C.

[0033] In some embodiments, the heat treatment is performed in a protective gas atmosphere, and the protective gas includes at least one of helium gas, neon gas, argon gas, nitrogen gas, and krypton gas.

[0034] In some embodiments, the time of the heat treatment is 1h to 24h.

[0035] According to a third aspect, an embodiment of the present application provides a lithium-ion battery, and the lithium-ion battery includes a negative electrode material described in the first aspect or a negative electrode material manufactured by the manufacturing method described in the second aspect.

Advantages of the Invention

[0036] The technical solution of this application has at least the following beneficial effects. The negative electrode material of this application includes carbonaceous particles with holes, and the aspect ratio of at least some of the holes being greater than 3 indicates that the shape of the holes in the carbonaceous particles of this application is elongated. The existence of the elongated holes indicates that the materials inside the carbonaceous particles are arranged orderly and the intercalated graphite layers inside the particles are in close contact, which is beneficial to improving the capacity performance of the negative electrode material. This application further limits the proportion of the number of holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes to 60% or more, which indicates that the carbonaceous particles with holes in this application have minute voids. The relatively low porosity of the carbonaceous particles indicates that the carbonaceous particles have a densified structure and can generate relatively small expansion during the charge and discharge process of the negative electrode material. The fact that the negative electrode material of this application has elongated holes and most of the holes have a relatively small hole diameter indicates that the internal hole volume of the carbonaceous particles in this application is small and the number of macro holes is relatively small. Thereby, due to the excellent compactness of the carbonaceous particles, the capacity performance, expansion performance and cycle performance of the negative electrode material are improved.

Brief Description of the Drawings

[0037] Hereinafter, this application will be further described by combining the drawings and examples.

Figure 1

Figure 2

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Figure 4

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Figure 6

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Figure 8

Embodiments for Carrying Out the Invention

[0038] To better understand the technical solutions of this specification, the embodiments of this application will be described in detail below in conjunction with the drawings.

[0039] It should be clearly stated that the described embodiments are only some embodiments of this specification, not all embodiments. Based on the embodiments in this specification, all other embodiments obtained without the creative efforts of those skilled in the art belong to the protection scope of this specification.

[0040] The terms used in the embodiments of this application are only for the purpose of describing specific embodiments and do not limit this specification. The singular forms "one", "the foregoing" and "this" used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0041] It should be understood that the term "and / or" used in this application only describes the relevant relationship of the relevant objects and represents that three relationships may exist. For example, ΔJ and / or B may represent three cases: when ΔJ exists alone, when ΔJ and B exist simultaneously, and when B exists alone. Also, the character " / " in this specification generally represents that the relevant objects before and after are in an "or" relationship.

[0042] In the field of anode materials, natural graphite mainly refers to spherical natural graphite obtained by processing flaky graphite. The reason for the poor cycle performance of such materials is mainly that during the lithium intercalation process of spherical natural graphite, co-intercalation occurs with organic molecules in the electrolyte, leading to structural damage of the graphite material. Therefore, natural graphite anode materials have a shorter cycle life and a larger expansion rate during the cycling process compared to artificial graphite. Currently, generally, a surface coating method is adopted in which a layer of amorphous carbon is coated on the surface of natural graphite to isolate the electrolyte from natural graphite and improve its performance.

[0043] At present, mainly the solid-phase coating method is adopted to coat the surface of natural graphite. The solid-phase coating method first mixes natural graphite and a coating modifier in a physical mixing manner, and then in the carbonization process, the coating modifier has a liquefaction process, and the liquefied coating modifier can be flowed to self-coat. Such a method is simple in operation, low in cost, and widely applied to the modification of natural graphite anode materials. However, in this process, small molecular substances in the modifier continue to volatilize, the liquefaction process is relatively short and cannot be controlled in terms of time. Therefore, the liquid coating agent cannot completely cover the outer surface of natural graphite, especially the surface of the flaky graphite inside the spherical graphite. During the cycling process, the electrolyte gradually penetrates into the surface of these uncoated natural graphite, continuously generates an SEI film, the electrolyte is continuously embedded in the natural graphite layer structure, consumes a large amount of active lithium, destroys the natural graphite structure, and leads to continuous attenuation of capacity.

[0044] In view of this, the present application provides an anode material. Referring to FIGS. 1 to 4, when observing the SEM image of the cross-section of the anode material, the anode material includes carbonaceous particles having holes. The aspect ratio of the holes in the anode material is greater than 3. When randomly observing 100 holes in total, the proportion of the number of holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is 60% or more.

[0045] In the above solution, the negative electrode material of the present application includes carbonaceous particles having holes, and the aspect ratio of the holes being greater than 3 indicates that the shape of the holes in the carbonaceous particles of the present application is elongated. The presence of the elongated holes indicates that the materials inside the carbonaceous particles are arranged in an orderly manner and the lamellar graphite interlayers inside the particles are in close contact, which is advantageous for enhancing the capacity performance of the negative electrode material. The present application further limits the ratio of the number of holes with a hole diameter of 0.1 μm to 0.5 μm in the holes to 60% or more of the total number of holes, which indicates that the carbonaceous particles with holes in the present application have minute voids. The relatively low porosity of the carbonaceous particles indicates that the carbonaceous particles have a densified structure and can generate relatively small expansion during the charge and discharge process of the negative electrode material. The fact that the negative electrode material of the present application has elongated holes and the hole diameters of most of the holes are relatively small indicates that the internal hole volume of the carbonaceous particles of the present application is small and the number of macro holes is relatively small. Thereby, due to the relatively good compactness of the carbonaceous particles, the capacity performance, expansion performance and cycle performance of the negative electrode material are improved.

[0046] In the present application, both the hole diameter and the hole length of the holes are obtained by measurement on an electron scanning electron microscope diagram. The fact that the shape of the holes in the carbonaceous particles described in the present application is elongated refers to the holes presenting a regular straight shape and the ratio of the major axis of the holes being greater than 3.

[0047] In some embodiments, the proportion of the number of holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is 60% or more. Specifically, it may be 60%, 65%, 70%, 75%, 80%, 85% or 90%, etc. Of course, it may also be other values within the above range, and the present application is not limited here. Being within the above limited range indicates that the carbonaceous particles of the present application have relatively small voids, and the diameters of most voids are within the range of 0.1 μm to 0.5 μm, indicating that the carbonaceous particles have a densified structure, a relatively low porosity, and can generate relatively small expansion during the charge and discharge process of the negative electrode material, which is beneficial for enhancing the expansion performance and cycle performance of the negative electrode material. If the proportion of the number of holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is less than 60%, there are relatively many holes with relatively large voids in the carbonaceous particles, and the expansion performance of the negative electrode material deteriorates.

[0048] In some embodiments, the maximum hole diameter of the holes is 3 μm or less. Specifically, it may be 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm, etc. Of course, it may also be other values within the above range, and the present application is not limited here. If the maximum hole diameter of the holes is greater than 3 μm, the contact between the internal materials of the carbonaceous particles is relatively loose, the densification effect is poor, and the expansion performance and cycle performance of the negative electrode material are relatively poor.

[0049] In some embodiments, the median diameter of the carbonaceous particles is 5 μm to 25 μm. Specifically, it may be 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm or 25 μm. Of course, it may also be other values within the above range, and the present application is not limited here.

[0050] In some embodiments, the carbonaceous particles contain natural graphite, which has a relatively low cost and excellent specific capacity compared to artificial graphite.

[0051] In some embodiments, the natural graphite contains at least one of flake graphite and microcrystalline graphite.

[0052] In some embodiments, the negative electrode material further includes a coating layer provided on at least a part of the surface of the carbonaceous particles. By providing the coating layer on the surface of the carbonaceous particles, while it is possible to reduce the entry of the electrolyte into the negative electrode material and the occurrence of side reactions, thereby reducing the initial efficiency and capacity, it is also possible to relieve the volume expansion of the carbonaceous particles, reduce the volume expansion of the entire negative electrode material, and reduce the swelling of the electrode plate.

[0053] In some embodiments, the material of the coating layer includes a carbon material.

[0054] In some embodiments, the carbon material includes at least one of soft carbon, crystalline carbon, amorphous carbon, and hard carbon.

[0055] In some embodiments, the median diameter D50 of the negative electrode material satisfies 5μm < D50 < 25μm. Specifically, the median diameter D50 of the negative electrode material may be 6μm, 8μm, 10μm, 13μm, 15μm, 18μm, 20μm, 22μm, or 24μm, etc. Of course, it may also be other values within the above range, and the present application is not limited here.

[0056] In some embodiments, the sphericity of the negative electrode material is Sh(10%) ≥ 0.75. Specifically, it may be 0.75, 0.75, 0.78, 0.80, 0.83, 0.85, 0.88, 0.90, or 0.95, etc. Of course, it may also be other values within the above range, and the present application is not limited here. The sphericity Sh(10%) is the sphericity corresponding when the particle size distribution number reaches 10%. Its physical meaning is that particles with a sphericity smaller (or larger) than it account for 10%.

[0057] In some embodiments, the sphericity of the negative electrode material satisfies Sh(50%)≧0.83. Specifically, it may be 0.83, 0.85, 0.88, 0.90, 0.95, etc. Of course, it may also be other values within the above range, and this application is not limited herein. The sphericity Sh(10%) refers to the sphericity corresponding when the particle size distribution number reaches 50%. Its physical meaning is that particles with a sphericity smaller (or larger) than this account for 50%.

[0058] In some embodiments, the sphericity of the negative electrode material satisfies Sh(90%)≧0.88. Specifically, it may be 0.88, 0.90, 0.95, etc. Of course, it may also be other values within the above range, and this application is not limited herein. The sphericity Sh(90%) refers to the sphericity corresponding when the particle size distribution number reaches 90%. Its physical meaning is that particles with a sphericity smaller (or larger) than this account for 90%.

[0059] The negative electrode material of this application has a relatively high sphericity and a relatively narrow sphericity distribution, and in the natural graphite particle negative electrode material, the internal materials are arranged orderly, and the lamellar graphite layers inside the particles are in close contact. The negative electrode material of this application has a relatively small specific surface area and a relatively large tap density, which is advantageous for suppressing the expansion of the negative electrode material and enhancing the expansion performance and cycle stability of the negative electrode material.

[0060] In some embodiments, the pore volume of the negative electrode material is 0.05 mL / g to 0.11 mL / g. Specifically, it may be 0.05 mL / g, 0.06 mL / g, 0.07 mL / g, 0.08 mL / g, 0.09 mL / g, 0.10 mL / g, 0.11 mL / g, etc. Of course, it may also be other values within the above range, and this application is not limited herein. The relatively small pore volume of the negative electrode material of this application indicates that the internal contact of the negative electrode material is relatively tight, which is advantageous for enhancing the expansion performance of the negative electrode material.

[0061] In some embodiments, the specific surface area of the negative electrode material is 0.5 m 2 / g to 3.5 m 2 / g, specifically, 0.5 m 2 / g, 0.7 m 2 / g, 1.0 m 2 / g, 1.3 m 2 / g, 1.5 m 2 / g, 1.8 m 2 / g, 2.3 m 2 / g, 2.8 m 2 / g, 3.0 m 2 / g or 3.5 m 2 / g etc. may be used, and of course, other values within the above range may also be used, and this application is not limited here.

[0062] This application further provides a method for manufacturing the above negative electrode material. As shown in FIG. 1, it is a manufacturing flowchart of the negative electrode material of this application. A step of providing a natural graphite precursor, wherein the natural graphite precursor has a median diameter of 5 μm to 25 μm, a sphericity of Sh(10%) ≥ 0.75, a sphericity of Sh(50%) ≥ 0.83, and a sphericity of Sh(90%) ≥ 0.88. A step of densifying the natural graphite precursor so that the obtained negative electrode material contains carbonaceous particles having holes, at least a part of the aspect ratio of the holes is greater than 3, and the proportion of the number of holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is 60% or more.

[0063] In the above solution, the present application adopts a natural graphite precursor with a specific particle size and morphology, and further densifies the natural graphite precursor. As a result, the negative electrode material of the present application has elongated holes and the hole diameters of most of the holes are relatively small, indicating that the carbonaceous particles produced in the present application have relatively high compactness. Moreover, since the natural graphite precursor of the present application has a relatively high sphericity, the influence on the morphology of the material is not significant during the densification process (i.e., the sphericity hardly changes before and after the densification process). Thereby, the negative electrode material produced in the present application has a high sphericity, and at the same time, has elongated holes inside and relatively small hole diameters, thereby improving the capacity performance, expansion performance and cycle performance of the negative electrode material. The manufacturing process of the present application is simple. By using a natural graphite raw material with a high sphericity and cooperating with specific process conditions, it is possible to achieve not filling or filling a small amount of the voids of the natural graphite particles, and at the same time reduce the internal voids to a predetermined level, and further solve the problems existing in the prior art, such as large expansion of the natural graphite negative electrode material and poor cycle performance.

[0064] If the sphericity of the natural graphite precursor is smaller than the limited range of the present application, in the subsequent densification process, even if the internal voids of the natural graphite precursor are compressed, the sphericity becomes smaller, the morphology deteriorates, the internal voids of the material are relatively small, and the lamellar graphite layers inside the particles are in close contact, it is impossible to obtain a negative electrode material with excellent expansion performance and cycle performance.

[0065] The following specifically introduces the manufacturing method of the present application in conjunction with the examples.

[0066] Step S100: Provide a natural graphite precursor.

[0067] Specifically, the natural graphite precursor includes being manufactured by a method of shaping natural graphite to obtain the natural graphite precursor. In some embodiments, the natural graphite includes at least one of flake graphite and microcrystalline graphite.

[0068] In some embodiments, the shaping device includes at least one of a mechanical grinder, a jet grinder, and a crusher.

[0069] In some embodiments, the particle size of the natural graphite precursor is 5 μm to 25 μm. Specifically, it may be 5 μm, 8 μm, 10 μm, 13 μm, 15 μm, 18 μm, 20 μm, 23 μm, or 25 μm. Of course, it may also be other values within the above range, and the present application is not limited herein.

[0070] In some embodiments, the sphericity of the natural graphite precursor is such that Sh(10%) ≥ 0.75. Specifically, it may be 0.75, 0.75, 0.78, 0.80, 0.83, 0.85, 0.88, 0.90, or 0.95, etc. Of course, it may also be other values within the above range, and the present application is not limited herein.

[0071] In some embodiments, the sphericity of the natural graphite precursor is such that Sh(50%) ≥ 0.83. Specifically, it may be 0.83, 0.85, 0.88, 0.90, or 0.95, etc. Of course, it may also be other values within the above range, and the present application is not limited herein.

[0072] In some embodiments, the sphericity of the natural graphite precursor is such that Sh(90%) ≥ 0.88. Specifically, it may be 0.88, 0.90, or 0.95, etc. Of course, it may also be other values within the above range, and the present application is not limited herein.

[0073] The natural graphite precursor of the present application has a relatively high sphericity, which is advantageous for suppressing the expansion of the negative electrode material and enhancing the expansion performance of the negative electrode material.

[0074] Step S200: Compact the natural graphite precursor so that the obtained negative electrode material contains carbonaceous particles with holes, the aspect ratio of at least some of the holes is greater than 3, and when randomly observing 100 holes in total, the proportion of holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is 60% or more, and the maximum hole diameter of the holes is 3 μm or less.

[0075] This application shows that by densifying graphite within a specific sphericity range to transform a natural graphite precursor into carbonaceous particles with closely contacting flaky graphite layers inside the particles, the particles having elongated voids and a relatively small pore diameter for most of the holes, the internal hole volume of the carbonaceous particles of this application is small and the number of macro holes is relatively small, whereby the carbonaceous particles have excellent compactness, thereby improving the capacity performance, expansion performance and cycle performance of the anode material.

[0076] In some embodiments, the densification treatment includes at least one of cold isostatic pressing, warm isostatic pressing, hot isostatic pressing, pressing treatment, and hot press forming.

[0077] In some embodiments, the pressure of the densification treatment using cold isostatic pressing is 60 MPa to 200 MPa. Specifically, it may be 60 MPa, 80 MPa, 100 MPa, 120 MPa, 150 MPa, 180 MPa or 200 MPa, etc. Of course, other values within the above range may also be used, and this application is not limited here.

[0078] In some embodiments, the pressure of the densification treatment without using cold isostatic pressing is 20 MPa to 200 MPa. Specifically, it may be 20 MPa, 60 MPa, 80 MPa, 100 MPa, 120 MPa, 150 MPa, 180 MPa or 200 MPa, etc. Of course, other values within the above range may also be used, and this application is not limited here. That is, the densification pressures of warm isostatic pressing, hot isostatic pressing, pressing treatment and hot press forming are 20 MPa to 200 MPa.

[0079] In some embodiments, the time of the densification treatment is 1 min to 200 min. Specifically, it may be 1 min, 10 min, 50 min, 100 min, 150 min or 200 min, etc. Of course, other values within the above range may also be used, and this application is not limited here.

[0080] In some embodiments, the temperature of the densification treatment is from 25°C to 1500°C. Specifically, it may be 25°C, 50°C, 100°C, 300°C, 500°C, 800°C, 1000°C, 1200°C, 1500°C, etc. Of course, it may also be other values within the above range, and the present application is not limited herein.

[0081] By adopting the above densification process, an appropriate natural graphite precursor can compress and reduce internal voids under the action of pressure, such that the proportion of holes with an aspect ratio of more than 3 and a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is 60% or more, and a negative electrode material with a maximum hole diameter of 3 μm or less can be obtained.

[0082] In some embodiments, after the densification treatment, the step of pulverizing the obtained material is further included.

[0083] In some embodiments, the median diameter of the material after pulverizing the densified material is from 5 μm to 25 μm. As can be understood, the densification treatment only has a relatively large impact on the voids inside the natural graphite precursor and does not have a large impact on the particle size of the material. Therefore, the median diameter of the material after pulverization is also controlled to be from 5 μm to 25 μm.

[0084] In some embodiments, before densifying the natural graphite precursor, the step of mixing the coating material and the natural graphite precursor is further included. Further, the above mixture is densified, that is, before the densification treatment, first, the coating material is coated on at least a part of the surface of the natural graphite precursor, and then, by the densification treatment, or simultaneously with densifying the natural graphite precursor, a coating layer is formed on the surface of the natural graphite precursor. Further, or first, after densifying the natural graphite precursor, a coating layer is formed on the surface of the natural graphite precursor. The order of the above steps may be adjusted according to the actual situation and is not specifically limited thereto.

[0085] In some embodiments, the coating material includes a carbon material. Preferably, the carbon material includes a carbon material with a softening point of 20°C to 300°C.

[0086] In some embodiments, the coating material includes at least one of a polymer, a resin, coal pitch, petroleum pitch, mesophase pitch, coal tar, and heavy oil.

[0087] In some embodiments, the mass ratio of the natural graphite precursor to the coating material is 100:(2 - 100), specifically, it may be 100:2, 100:10, 100:20, 100:50, 100:80, or 100:100, etc. Of course, it may also be other values within the above range, and the present application is not limited herein.

[0088] Step S300: After mixing the negative electrode material obtained in step S200 with the coating material, perform heat treatment.

[0089] As can be understood, after performing the operation of performing the densification treatment after mixing the natural graphite precursor and the coating material in step S200, step S300 may be omitted.

[0090] In some embodiments, the coating material includes a carbon material. Preferably, the carbon material includes a carbon material having a softening point of 20°C to 300°C.

[0091] In some embodiments, the coating material includes at least one of a polymer, a resin, coal pitch, petroleum pitch, mesophase pitch, coal tar, and heavy oil.

[0092] In some embodiments, the mass ratio of the negative electrode material to the coating material is 100:(2 - 100), specifically, it may be 100:2, 100:10, 100:20, 100:50, 100:80, or 100:100, etc. Of course, it may also be other values within the above range, and the present application is not limited herein.

[0093] In some embodiments, the temperature of the heat treatment is 800°C to 3000°C. Specifically, it may be 800°C, 1000°C, 1200°C, 1500°C, 1800°C, 2000°C, 2500°C, 2800°C, 3000°C, etc. Of course, it may also be other values within the above range, and the present application is not limited here.

[0094] In some embodiments, the heat treatment is carried out in a protective gas atmosphere, and the protective gas contains at least one of helium gas, neon gas, argon gas, nitrogen gas, and krypton gas.

[0095] In some embodiments, the time of the heat treatment is 1h to 24h. Specifically, it may be 1h, 5h, 12h, 15h, 18h, 24h, etc. Of course, it may also be other values within the above range, and the present application is not limited here.

[0096] In some embodiments, after the heat treatment, the steps of crushing, sieving, and demagnetizing the obtained material are further included.

[0097] In some embodiments, the mesh number of the sieving is 100 mesh to 500 mesh. Specifically, it may be 100 mesh, 200 mesh, 300 mesh, 400 mesh, 500 mesh, etc. Of course, it may also be other values within the above range, and the present application is not limited here.

[0098] According to a third aspect, the present application further provides a lithium-ion battery, and this lithium-ion battery includes the above negative electrode material or a negative electrode material manufactured by the above manufacturing method.

[0099] The following further describes the present application by specific examples.

[0100] Example 1 (1) The natural flaky graphite was pulverized and shaped to obtain spherical natural graphite with an average particle size of 17 μm, and the sphericity of the spherical natural graphite satisfied Sh(10%)≥0.75, Sh(50%)≥0.83, and Sh(90%)≥0.88.

[0101] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in a cold isostatic press. The operating pressure was set at 100 MPa, the time was 30 min, and the temperature was 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 17 μm after pulverization.

[0102] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln in an inert atmosphere. The carbonization temperature was 1000 °C. After carbonization, the material was scattered, sieved, and demagnetized to obtain a negative electrode material.

[0103] As shown in Fig. 2, the SEM image of the cross-section of the negative electrode material manufactured in this example observed that there were elongated voids inside the natural graphite in Fig. 2.

[0104] Example 2 (1) The natural flaky graphite was pulverized and shaped to obtain spherical natural graphite with an average particle size of 17 μm, and the sphericity of the spherical natural graphite satisfied Sh(10%)≥0.75, Sh(50%)≥0.83, and Sh(90%)≥0.88.

[0105] (2) The spherical natural graphite obtained in step (1) and petroleum pitch were mixed at a ratio of 90:10, and the mixture was processed using a hot press. The heating temperature was 1000 °C, the pressure was 25 MPa, and the time was 30 min. The processed material was massive graphite. The massive graphite was crushed and pulverized to obtain a negative electrode material with a particle median diameter of 17 μm after pulverization.

[0106] As shown in Fig. 3, the SEM image of the cross-section of the negative electrode material manufactured in this example observed that there were elongated voids inside and on the surface of the natural graphite in Fig. 3.

[0107] Example 3 (1) Natural flaky graphite was crushed and shaped to obtain spherical natural graphite with an average particle size of 17 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0108] (2) The spherical natural graphite obtained in step (1) and petroleum pitch were mixed at a ratio of 80:20, and the mixture was pretreated using a heating mixer protected in an inert atmosphere. The temperature was set at 300 °C and the mixing time was set at 5 h. The treated material was made into massive graphite.

[0109] (3) The massive graphite obtained in step (2) was processed with a press machine, the pressure was set at 25 MPa, and the processing time was set at 30 min. A densified natural graphite block was obtained after the treatment. Then the densified natural graphite block was crushed and pulverized to obtain a negative electrode material with a particle median diameter of 17 μm after pulverization.

[0110] As shown in FIG. 4, the SEM image of the cross-section of the negative electrode material manufactured in this example observed that there were elongated voids inside the natural graphite in FIG. 4.

[0111] Example 4 (1) Natural flaky graphite was crushed and shaped to obtain spherical natural graphite with an average particle size of 5 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0112] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in a cold isostatic press, the operating pressure was set at 100 MPa, the time was set at 30 min, and the temperature was set at 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 5 μm after pulverization.

[0113] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln in an inert atmosphere. The carbonization temperature was set at 1000 °C. After carbonization, the material was scattered, sieved, and demagnetized to obtain a negative electrode material.

[0114] As shown in Fig. 5, the SEM image of the cross-section of the negative electrode material manufactured in this example shows that elongated voids were observed inside and on the surface of the natural graphite.

[0115] Example 5 (1) Natural flaky graphite was pulverized and shaped to obtain spherical natural graphite with an average particle size of 11 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0116] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in a cold isostatic press with an operating pressure of 100 MPa, a time of 30 min, and a temperature of 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 11 μm after pulverization.

[0117] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln under an inert atmosphere at a carbonization temperature of 1000 °C. After carbonization, the material was broken up, sieved, and demagnetized to obtain a negative electrode material.

[0118] Example 6 (1) Natural flaky graphite was pulverized and shaped to obtain spherical natural graphite with an average particle size of 25 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0119] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in a cold isostatic press with an operating pressure of 100 MPa, a time of 30 min, and a temperature of 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 25 μm after pulverization.

[0120] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln under an inert atmosphere. The carbonization temperature was set at 1000 °C. After carbonization, the material was crushed, sieved, and demagnetized to obtain a negative electrode material.

[0121] Example 7 (1) Natural flaky graphite was crushed and shaped to obtain spherical natural graphite with an average particle size of 17 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0122] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in an isostatic cold pressing machine. The operating pressure was set at 60 MPa, the time was 30 min, and the temperature was 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 17 μm after pulverization.

[0123] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln under an inert atmosphere. The carbonization temperature was set at 1000 °C. After carbonization, the material was crushed, sieved, and demagnetized to obtain a negative electrode material.

[0124] Example 8 (1) Natural flaky graphite was crushed and shaped to obtain spherical natural graphite with an average particle size of 17 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0125] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in an isostatic cold pressing machine. The operating pressure was set at 200 MPa, the time was 30 min, and the temperature was 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 17 μm after pulverization.

[0126] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln under an inert atmosphere. The carbonization temperature was set at 1000 °C. After carbonization, the material was crushed, sieved, and demagnetized to obtain a negative electrode material.

[0127] Example 9 (1) Natural flaky graphite was crushed and shaped to obtain spherical natural graphite with an average particle size of 17 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0128] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in a cold isostatic press. The operating pressure was set at 250 MPa, the time was 30 min, and the temperature was 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 17 μm.

[0129] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln under an inert atmosphere. The carbonization temperature was set at 1000 °C. After carbonization, the material was crushed, sieved, and demagnetized to obtain a negative electrode material.

[0130] Example 10 The difference from Example 1 is that step (3) is not performed.

[0131] Comparative Example 1 (1) Natural flaky graphite was crushed and shaped to obtain spherical natural graphite with an average particle size of 17 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0132] (2) The spherical natural graphite obtained in step (1) and pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln under an inert atmosphere. The carbonization temperature was set at 1000 °C. After carbonization, the material was crushed, sieved, and demagnetized to obtain a negative electrode material.

[0133] As shown in Fig. 6, the SEM image of the cross-section of the negative electrode material produced in this comparative example showed that elongated voids were observed inside and on the surface of the natural graphite in Fig. 6.

[0134] Comparative Example 2 (1) Natural flaky graphite was pulverized and shaped to obtain spherical natural graphite with an average particle size of 17 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0135] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in a cold isostatic pressing machine, the operating pressure was set at 50 MPa to obtain massive graphite, and the massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 17 μm after pulverization.

[0136] (3) The densified natural graphite obtained in step (2) and pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln in an inert atmosphere at a carbonization temperature of 1000 °C. After carbonization, the material was scattered, sieved, and demagnetized to obtain a negative electrode material.

[0137] As shown in Fig. 7, the SEM image of the cross-section of the negative electrode material produced in this comparative example showed that natural graphite had voids, and it was observed that the number of voids was relatively large and they exhibited an irregular shape in Fig. 7.

[0138] Comparative Example 3 (1) Natural flaky graphite was pulverized and shaped to obtain spherical natural graphite with an average particle size of 17 μm. The sphericity of the spherical natural graphite was Sh(10%) = 0.72, Sh(50%) = 0.79, and Sh(90%) = 0.87.

[0139] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in a cold isostatic pressing machine, the operating pressure was set at 100 MPa, the time was set at 30 min, and the temperature was set at 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 17 μm after pulverization.

[0140] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln under an inert atmosphere. The carbonization temperature was set at 1000 °C. After carbonization, the material was crushed, sieved, and demagnetized to obtain a negative electrode material.

[0141] As shown in Fig. 8, the SEM image of the cross-section of the negative electrode material manufactured in this comparative example shows that in Fig. 8, natural graphite has voids, and it was observed that the number of voids is relatively large and they exhibit an irregular shape.

[0142] Comparative Example 4 (1) Natural flaky graphite was crushed and shaped to obtain spherical natural graphite with an average particle size of 30 μm. The sphericity of the spherical natural graphite satisfied Sh(10%) ≥ 0.75, Sh(50%) ≥ 0.83, and Sh(90%) ≥ 0.88.

[0143] (2) The spherical natural graphite obtained in step (1) was densified. The densification was carried out in a cold isostatic press. The operating pressure was set at 100 MPa, the time was 30 min, and the temperature was 30 °C to obtain massive graphite. The massive graphite was crushed and pulverized to obtain densified natural graphite with a particle median diameter of 30 μm after pulverization.

[0144] (3) The densified natural graphite obtained in step (2) and petroleum pitch were solid-phase mixed at a mass ratio of 90:10, and the mixed material was carbonized in a kiln under an inert atmosphere. The carbonization temperature was set at 1000 °C. After carbonization, the material was crushed, sieved, and demagnetized to obtain a negative electrode material.

[0145] Performance Test (1) The median diameter D50 of the negative electrode material was tested using a Malvern laser particle size tester MS 2000.

[0146] (2) The sphericity Sh(10%), Sh(50%), and Sh(90%) of the material were tested using a SYMPATEC QICPIC dynamic particle image analyzer.

[0147] (3) The specific surface area test of the negative electrode material was carried out using a Micromeritics Tristar instrument.

[0148] (4) The pore volume of the material was tested using a mercury porosimeter Micromeritics AutoPore IV 9500, and the pore volume within the range of pore diameters from 3 nm to 1000 nm was measured.

[0149] (5) The test of the electrode plate expansion rate was carried out for 20 cycles using the test device and system disclosed in Patent CN201920973729.5.

[0150] (6) Using an ion mill (HITACHI E3500) sample, the particle sample was milled so that the cross-section of the particle could be observed. The sample was placed under a high-magnification electron microscope (HITACHI S4800) to observe and obtain the internal information of the particle. The void width within the selected area was measured and counted using a scale. When randomly observing 100 holes in total, the number of holes less than 0.1 μm, between 0.1 and 0.5 μm, and more than 0.5 μm was statistically counted respectively, and the ratio was calculated. The holes less than 0.1 μm, between 0.1 and 0.5 μm, and more than 0.5 μm were defined as micro-holes, meso-holes, and macro-holes respectively. The number of these three types of holes was statistically counted and the ratio was calculated. The aspect ratio of the hole is to observe and obtain the internal information of the particle under a high-magnification electron microscope (HITACHI S4800), measure the length and width of the void within the selected area using a scale, and obtain the ratio of the two, which is the aspect ratio of the hole.

[0151] (7) The negative electrode material, conductive agent, and adhesive were dissolved and mixed in a solvent at a mass percentage of 94:1:5, and the solid content was controlled to 50%. It was coated on a copper foil current collector and vacuum dried to obtain a negative electrode plate. Then, a ternary positive electrode plate manufactured by a conventional mature process, a 1 mol / L LiPF6 / EC + DMC + EMC (v / v = 1:1:1) electrolyte, a Celgard 2400 separator, and a housing were used to assemble a 18650 cylindrical single cell using a normal production process. The charge and discharge test of the cylindrical battery was carried out on the LAND battery test system of Wuhan Jinnuo Electronics Co., Ltd. Under normal temperature conditions, it was charged and discharged at a constant current of 0.2C, and the charge and discharge voltage was limited to 2.75 - 4.2V. The initial reversible capacity, the charge capacity of the first cycle, and the discharge capacity of the first cycle were obtained. The initial Coulomb efficiency = the discharge capacity of the first cycle / the charge capacity of the first cycle.

[0152] 50 cycles were repeated, and the discharge capacity was recorded as the remaining capacity of the lithium-ion battery. The capacity retention rate = remaining capacity / initial capacity * 100%.

[0153] Measurement of the expansion rate (%) of the electrode plate after 20 cycles: The negative electrode material, conductive agent, and adhesive were dissolved and mixed in a solvent at a mass percentage of 94:1:5, and the solid content was controlled to 50%. It was coated on a copper foil current collector and vacuum dried to obtain a negative electrode plate. The loading amount of the negative electrode material on the electrode plate was controlled to 7.0 mg / cm 2 and the compaction density of the electrode plate after roll compression was 1.60 g / cm 3 . The thickness of the test electrode plate was set as d1, and it was assembled into a button-type battery for testing. After 20 cycles, the battery was removed, and the electrode plate thickness d2 was tested again. The electrode plate expansion rate = (d2 - d1) / d1 * 100%.

[0154] The test results are as shown in Table 1 and Table 2.

[0155] Table 1 Parameter test results of the negative electrode materials of each example and comparative example JPEG2025524285000002.jpg77124

[0156] As can be understood, the hole shapes described in Comparative Example 2 and Comparative Example 3 are irregular. By "irregular", it means that the holes on the natural graphite are not elongated, that is, the holes are not arranged in a linear pattern, and / or the aspect ratio of the holes is 3 or less.

[0157] Table 2 Performance test data of each example and comparative example JPEG2025524285000003.jpg144166

[0158] As shown in Table 1 and Table 2, the negative electrode materials manufactured in Examples 1 to 10 of the present application contain carbonaceous particles having holes, and the hole shape of the carbonaceous particles being an elongated structure indicates that the materials inside the carbonaceous particles are arranged in an orderly manner and the internal flaky graphite layers of the particles are in close contact, which is advantageous for enhancing the capacity performance of the negative electrode material. The present application further limits the ratio of holes with a hole diameter of 0.1 μm to 0.5 μm to 60% or more of the total number of holes, indicating that the carbonaceous particles having holes in the present application have minute voids, and the relatively low porosity of the carbonaceous particles indicates that the carbonaceous particles have a densified structure and can generate relatively small expansion during the charge and discharge process of the negative electrode material. The fact that the negative electrode material of the present application has elongated holes and the hole diameters of most of the holes are relatively small indicates that the internal hole volume of the carbonaceous particles in the present application is small and the number of macro holes is relatively small. As a result, the carbonaceous particles have excellent compactness, thereby improving the capacity performance, expansion performance and cycle performance of the negative electrode material.

[0159] The negative electrode material manufactured in Comparative Example 1 has not been subjected to densification treatment, whereby the hole volume of the negative electrode material manufactured in Comparative Example 1 becomes relatively large and the porosity becomes relatively high, and the expansion performance and cycle performance of the negative electrode material manufactured in Comparative Example 1 deteriorate.

[0160] The operating pressure of the cold isostatic press in Comparative Example 2 is not within the limitation range of the present application. The holes of the negative electrode material manufactured in Comparative Example 2 exhibit an irregular shape, and the hole volume is relatively high. Both its capacity and initial efficiency are lower than those of Example 1.

[0161] The sphericity of the graphite raw material in Comparative Example 3 was not within the limited scope of the present application. The sphericity of the manufactured negative electrode material was relatively poor, the expansion of the material was relatively high, and the material had elongated micro-holes inside. However, the expansion performance of the material was still relatively poor.

[0162] The particle size of the graphite raw material in Comparative Example 4 was not within the limited scope of the present application. The densification effect of the manufactured negative electrode material was relatively poor, and the material had a considerable number of elongated micro-holes inside. However, there were still a small number of macro-holes present. Finally, the expansion of the manufactured negative electrode material was relatively high, and the cycle performance was relatively poor.

[0163] As described above, it is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, various modifications and changes are possible to the present application. Any modifications, equivalent replacements, improvements, etc. made within the scope of the spirit and principle of the present application should all be included within the protection scope of the present application.

Claims

1. A negative electrode material, wherein the negative electrode material includes carbonaceous particles having holes, and at least the aspect ratio of the holes is greater than 3 as observed by SEM image. When randomly observing 100 holes in total, the proportion of the holes with a hole diameter of 0.1 μm to 0.5 μm in the total number of holes is 60% or more. The negative electrode material is characterized by this.

2. The maximum hole diameter of the holes is 3 μm or less. The negative electrode material according to Claim 1 is characterized by this.

3. The negative electrode material (1) The carbonaceous particles contain graphite, and (2) the carbonaceous particles contain natural graphite, and the natural graphite contains at least one of flake graphite and microcrystalline graphite, and (3) the median diameter of the carbonaceous particles is 5 μm to 25 μm. The negative electrode material according to Claim 1 is characterized by including at least one of these features.

4. The negative electrode material further includes a coating layer covering at least a part of the surface of the carbonaceous particles. The negative electrode material (1) The material of the coating layer includes a carbon material, and (2) the material of the coating layer includes a carbon material, and the carbon material includes at least one of soft carbon, crystalline carbon, amorphous carbon, and hard carbon. The negative electrode material according to Claim 1 is characterized by including at least one of these features.

5. The negative electrode material (1) The median diameter D50 of the negative electrode material satisfies 5 μm < D50 < 25 μm, (2) The sphericity of the negative electrode material is Sh(10%) ≥ 0.75, (3) The sphericity of the negative electrode material is Sh(50%) ≥ 0.83, (4) The sphericity of the negative electrode material is Sh(90%) ≥ 0.88, (5) The hole volume of the negative electrode material is 0.05 mL / g to 0.11 mL / g. (6) The specific surface area of the negative electrode material is at least one of 0.5 m ２ / g to 3.5 m ２ / g, and the negative electrode material according to claim 1, characterized in that it includes at least one of the above features.

6. A method for manufacturing a negative electrode material, which includes a step of providing a natural graphite precursor, wherein the median diameter of the natural graphite precursor is 5 μm to 25 μm, the sphericity of the natural graphite precursor is Sh(10%) ≥ 0.75, the sphericity of the natural graphite precursor is Sh(50%) ≥ 0.83, and the sphericity of the natural graphite precursor is Sh(90%) ≥ 0.

88. The step of densifying the natural graphite precursor to obtain a negative electrode material containing carbonaceous particles having holes, wherein the aspect ratio of at least a part of the holes is greater than 3, and when observing 100 holes randomly, the ratio of the number of holes with a hole diameter of 0.1 μm to 0.5 μm to the total number of holes is 60% or more, and a manufacturing method of a negative electrode material characterized by including this.

7. The manufacturing method is (1) the natural graphite precursor is manufactured by a method of shaping natural graphite, and (2) the natural graphite precursor is manufactured by a method of shaping natural graphite, and the natural graphite includes at least one of flake graphite and microcrystalline graphite, and the manufacturing method according to claim 6 characterized by including at least one of the features.

8. The manufacturing method is (1) the densification treatment includes at least one of cold isostatic pressing, hot isostatic pressing, pressing, and hot press forming, and (2) the pressure of the densification treatment is 20 MPa to 200 MPa, and (3) the time of the densification treatment is 1 min to 200 min, and (4) the temperature of the densification treatment is 25°C to 1500°C, and the manufacturing method according to claim 6 characterized by including at least one of the features.

9. Before densifying the natural graphite precursor, the method further includes a step of mixing a coating material and the natural graphite precursor, and further densifying the mixture, and the coating material includes at least one of a polymer, a resin, coal pitch, petroleum pitch, mesophase pitch, coal tar, and heavy oil, and the manufacturing method according to claim 6 characterized by this.

10. After obtaining the negative electrode material, the method further includes a step of performing heat treatment after mixing the negative electrode material and a coating material, and the manufacturing method is (1) the coating material includes at least one of a polymer, a resin, coal pitch, petroleum pitch, mesophase pitch, coal tar, and heavy oil, and (2) the mass ratio of the negative electrode material to the coating material is 100:(2 to 100), and (3) the temperature of the heat treatment is 800°C to 3000°C (4) The heat treatment is performed in a protective gas atmosphere, and the protective gas contains at least one of helium gas, neon gas, argon gas, nitrogen gas, and krypton gas. (5) The manufacturing method according to claim 6, characterized by including at least one of the features that the time of the heat treatment is 1 h to 24 h.

11. A lithium-ion battery, comprising a negative electrode material according to any one of claims 1 to 5, or a negative electrode material manufactured by the manufacturing method according to any one of claims 6 to 10.

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