Carbon materials and methods for producing the same, as well as secondary batteries and power consumption devices using the same.

Abstract

This application relates to a carbon material including a pore structure and satisfying 0.150 ≦ I D / I G ≦ 0.280, where I D represents the D-peak intensity at 1350 ± 50 cm -1 in the Raman spectrum of the carbon material, and I G represents the G-peak intensity at 1580 ± 50 cm -1 in the Raman spectrum of the carbon material. Also provided are a method for producing the carbon material, a secondary battery including the same, and a power consumption device. The carbon material according to this application can endow the secondary battery with high initial Coulomb efficiency, high energy density, good cycle performance, and good storage performance.

Description

[Technical Field]

[0001] This application relates to the field of battery technology, and more specifically to carbon materials and methods for manufacturing the same, as well as secondary batteries and power consumption devices containing the same. [Background technology]

[0002] In recent years, secondary batteries have been widely used in many fields, including energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. As the range of applications for secondary batteries expands, serious challenges are being posed to their performance. For example, secondary batteries are required to possess a combination of various performance characteristics, such as energy density and service life. The negative electrode active material is a crucial component of secondary batteries and affects their performance. Currently, negative electrode active materials mainly consist of graphite, but the problems faced in conventional technology are the difficulty in combining high-capacity graphite with high initial Coulomb efficiency, and the difficulty in combining good cycle performance and storage performance in secondary batteries. [Overview of the project]

[0003] The present invention aims to provide a carbon material and a method for manufacturing the same that can be used in secondary batteries to combine high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance, as well as a secondary battery and a power consumption device containing the same.

[0004] A first aspect of the present application provides a carbon material comprising a porosity structure and having a 0.150 ≤ I D / I G Satisfying ≤ 0.280, I D This is the Raman spectrum of the carbon material at 1350±50 cm⁻¹. -1 This represents the D peak intensity at I G This is the Raman spectrum of the carbon material at 1580±50 cm⁻¹. -1 This represents the G-peak intensity in that region.

[0005] The carbon material according to the present application can effectively reduce the irreversible capacity loss of a secondary battery, improve the capacity performance of the secondary battery, and endow the secondary battery with high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0006] In any embodiment of the present application, 0.152 ≤ I D / I G ≤ 0.280, and optionally, 0.155 ≤ I D / I G ≤ 0.220. When the I D / I G of the carbon material is further adjusted within the above range, the secondary battery can be more suitably equipped with high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0007] In any embodiment of the present application, the carbon material includes one or more pore structures with a pore area of 0.15 μm 2 or more, and optionally, includes one or more pore structures with a pore area of 0.15 μm 2 to 2.0 μm 2 . When the carbon material includes a pore structure having the above pore area, the pore structure can ensure an expansion space required for the volume change of the carbon material particles, thereby further reducing the risk of generation of a new interface due to crushing of the carbon material particles, and thus reducing the occurrence of side reactions, reducing the irreversible capacity loss of the secondary battery, and improving the cycle performance and storage performance of the secondary battery.

[0008] In any embodiment of the present application, the carbon material includes an external region and an internal region located inside the external region. The external region is a region formed by extending 0.25L from the particle surface of the carbon material to the inside of the particle, where L is the short axis length of the carbon material particle. When the total pore area of the external region is S1 and the total pore area of the internal region is S2, S2 > S1.

[0009] In any embodiment of the present application, 1.5 ≤ S2 / S1 ≤ 450, and selectively, 2 ≤ S2 / S1 ≤ 400.

[0010] When S2 / S1 satisfies the above range, the secondary battery can more effectively combine high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0011] In any embodiment of the present application, 0.01 μm 2 ≤S1 ≤ 5.0 μm 2 Therefore, selectively, 0.02 μm 2 ≤S1 ≤ 4.5 μm 2 Therefore, if the total pore area of ​​the external region of the carbon material is within the above range, the carbon material particles can be given a more stable structure, thereby minimizing the penetration of the electrolyte into the pore structure inside the carbon material particles, reducing the occurrence of side reactions, and reducing the consumption of active ions due to the formation of SEI films inside the carbon material particles, while not affecting the transport performance of active ions and electrons.

[0012] In any embodiment of this application, 2.5 μm 2 ≤S2 ≤ 25.0 μm 2 Therefore, selectively, 3.0 μm 2 ≤S2 ≤ 22.5 μm 2 Therefore, when the total pore area of ​​the internal region of the carbon material is within the above range, a sufficient and stable expansion space can be secured for volume changes of the carbon material particles, reducing the risk of new interfaces being generated due to the fragmentation of carbon material particles, reducing the occurrence of side reactions on the surface of the new interfaces, and reducing the consumption of active ions due to the formation of SEI films on the surface of the new interfaces, while improving the capacity and initial Coulomb efficiency of the carbon material.

[0013] In any embodiment of the present application, L ≥ 4 μm, and selectively, 4 μm ≤ L ≤ 20 μm.

[0014] In any embodiment of the present application, the area of ​​the pore structure in the external region of the carbon material is 0.15 μm². 2 The following applies, with selectable 0.10 μm2 The following is true: By controlling the area of ​​the pore structure in the external region of the carbon material to within the above range, a dense structure can be created in the external region of the carbon material. This effectively improves the structural stability of the carbon material, minimizes the penetration of the electrolyte into the pore structure inside the carbon material particles, and consequently effectively improves the cycle performance and storage performance of the secondary battery.

[0015] In any embodiment of the present application, the internal region of the carbon material has an area of ​​0.15 μm 2 It includes one or more pore structures, selectively with an area of ​​0.15 μm². 2 ~2.0μm 2 The carbon material contains one or more pore structures. When the internal region of the carbon material contains pore structures of the above area, it is possible to secure sufficient and stable expansion space for volume changes of the carbon material particles, reduce the risk of fragmentation of the carbon material particles, and improve the compressive density of the carbon material.

[0016] In any embodiment of the present application, if the interlayer distance of the outer region of the carbon material is denoted as d1 and the interlayer distance of the inner region of the carbon material is denoted as d2, then the carbon material satisfies d1≧d2, and selectively, d1>d2. The large interlayer distance of the outer region of the carbon material is advantageous for the rapid insertion and removal of active ions, thus further improving the dynamic performance of the secondary battery. The small interlayer distance of the inner region of the carbon material is advantageous for increasing the gram capacity (capacity per gram) and compressive density of the carbon material, thus further increasing the energy density of the secondary battery.

[0017] In any embodiment of the present application, d1 is between 0.33565 nm and 0.33620 nm.

[0018] In any embodiment of the present application, d2 is 0.33557 nm to 0.33589 nm.

[0019] In any embodiment of the present application, the specific surface area of ​​the carbon material is 2.1 m². 2 It is less than / g and selectively 0.7m2 / g~1.8m 2 The value is / g. Since the carbon material of this application has a low specific surface area and low surface activity, it can reduce the consumption of active ions due to the formation of SEI films, improve the initial Coulomb efficiency of the carbon material, and further improve the cycle performance and storage performance of secondary batteries.

[0020] In any embodiment of the present application, the volume-distributed particle size Dv50 of the carbon material is 6.0 μm to 30.0 μm, and selectively 8.0 μm to 25.0 μm.

[0021] In any embodiment of the present application, the volume-distributed particle size Dv90 of the carbon material is 16.0 μm to 45.0 μm, and selectively 17.0 μm to 42.0 μm.

[0022] If the volume distribution particle size Dv50 and / or Dv90 of the carbon material is within the above range, it is advantageous for improving the transport performance of active ions and electrons, and thus the cycle performance and dynamic performance of the secondary battery can be further improved.

[0023] In any embodiment of the present application, the particle size distribution (Dv90-Dv10) / Dv50 of the carbon material is 1.55 or less, and selectively between 0.5 and 1.50. This is advantageous for improving the compressive density of the carbon material, and thus can further improve the energy density of the secondary battery.

[0024] In any embodiment of the present application, the powder resistivity of the carbon material under a pressure of 8 MPa is 0.006 Ω·cm to 0.051 Ω·cm, and selectively between 0.010 Ω·cm and 0.040 Ω·cm. Having the powder resistivity of the carbon material within this range is advantageous for improving electron transport performance, thereby further improving the cycle performance and dynamic performance of the secondary battery.

[0025] In any embodiment of the present application, the powder compression density of the carbon material under a pressure of 20,000 N is 1.70 g / cm³. 3 ~1.95g / cm 3Therefore, it is selectable to 1.72 g / cm³. 3 ~1.92g / cm 3 Therefore, if the compressed density of the carbon material powder is within the above range, the compressed density of the negative electrode sheet can be increased, further increasing the energy density of the secondary battery. This is also advantageous for improving the transport performance of active ions and electrons, thereby improving the cycle performance and dynamic performance of the secondary battery.

[0026] In any embodiment of the present application, the tap density of the carbon material is 0.80 g / cm³. 3 ~1.35g / cm 3 Therefore, it is selectable to 0.85 g / cm³. 3 ~1.30g / cm 3 Therefore, if the tap density of the carbon material is within the above range, the compressive density of the negative electrode sheet can be increased, further increasing the energy density of the secondary battery. This is also advantageous for improving the transport performance of active ions and electrons, thus improving the cycle performance and dynamic performance of the secondary battery.

[0027] In any embodiment of the present application, the gram capacity of the carbon material is 350 mAh / g to 372 mAh / g, and selectively 353 mAh / g to 371 mAh / g. When the gram capacity of the carbon material is within the above range, the energy density of the secondary battery can be increased.

[0028] In any embodiment of the present application, the degree of graphitization of the carbon material is 92.0% to 98.0%, and selectively 92.5% to 97.6%. Having the degree of graphitization of the carbon material within the above range is advantageous for providing secondary batteries with high energy density, good cycle performance, storage performance, and dynamic performance.

[0029] In any embodiment of the present application, the topography of the carbon material includes one or more of the following: lumpy, spherical, and subglobular.

[0030] A second aspect of the present application is a method for producing a carbon material, comprising: step 1 providing a raw material having a plurality of pore structures; step 2 uniformly mixing the raw material and a filler in a predetermined ratio, and then maintaining the mixture at a first temperature T1 for a first time t1 to obtain an intermediate; and step 3 maintaining the obtained intermediate at a second temperature T2 for a second time t2 to obtain a carbon material, wherein the carbon material includes pore structures, and the carbon material has a density of 0.150 ≤ I D / I G Satisfying ≤ 0.280, I D This is the Raman spectrum of the carbon material at 1350±50 cm⁻¹. -1 This represents the D peak intensity at I G This is the Raman spectrum of the carbon material at 1580±50 cm⁻¹. -1 This invention provides a method for producing carbon materials that represents the G-peak intensity in a given region.

[0031] In any embodiment of the present application, the raw material comprises natural graphite, optionally comprising one or more of the following: flake graphite, natural spheroidal graphite, and microcrystalline graphite.

[0032] In any embodiment of the present application, the volume distribution particle size Dv50 of the raw material is 6.0 μm to 30.0 μm, and selectively 8.0 μm to 25.0 μm.

[0033] In any embodiment of the present application, the specific surface area of ​​the raw material is 2.5 m². 2 It is 2.5m or more and can be selected. 2 / g~10.0m 2 It is / g.

[0034] In any embodiment of the present application, the softening point temperature of the filler is 100°C to 180°C, and selectively 120°C to 160°C.

[0035] In any embodiment of the present application, the coke value of the filler is 25% to 50%, and selectively 30% to 42%.

[0036] In any embodiment of the present application, the volume distribution particle size Dv50 of the filler is 6 μm or less, and selectively 1 μm to 5 μm.

[0037] In any embodiment of the present application, the filler includes one or more of coal pitch, petroleum pitch, polymer compounds, and resins, and optionally includes one or more of coal pitch and petroleum pitch.

[0038] In any embodiment of the present application, the mass ratio of the filler to the raw material is (10-32):100, and selectively (15-25):100.

[0039] By adjusting parameters such as the type of filler, softening point, coke value, and amount of additive within the above range, the filler, after melting due to heat, does not have high viscosity and maintains good fluidity. Furthermore, it reduces the adhesion of raw material particles and the aggregation of raw material particles in subsequent manufacturing processes. This reduces problems such as an increase in surface defects and surface active sites of carbon material particles due to the depolymerization process.

[0040] In any embodiment of the present application, the heating step of uniformly mixing the raw material and the filler in a predetermined ratio and then raising the temperature to a first temperature T1 is a stepwise heating step and optionally includes a first heating step, a second heating step, and a third heating step.

[0041] In any embodiment of the present application, the first heating step involves heating to 200°C to 250°C and maintaining the temperature at that temperature for 1 to 2 hours.

[0042] In any embodiment of the present application, the second heating step involves heating to 450°C to 550°C and maintaining the temperature at that temperature for 1 to 2 hours.

[0043] In any embodiment of the present application, the third heating step involves heating up to the first temperature T1 and maintaining that temperature for a first time t1.

[0044] In any embodiment of the present invention, the temperature is raised to the first temperature T1 at a rate of 1°C / min to 10°C / min.

[0045] In any embodiment of the present application, the first temperature T1 is 700°C to 1200°C, and selectively 720°C to 1100°C.

[0046] In any embodiment of the present application, the first time t1 is 1h to 5h, and selectively 2h to 4h.

[0047] Adjusting one or more of the heating rate, first temperature, first time, heating process, etc., within the above range is advantageous for producing a carbon material with a desired structure.

[0048] In any embodiment of the present application, the second temperature T2 is 1800°C to 2600°C, and selectively 1900°C to 2450°C.

[0049] In any embodiment of the present application, the second time t2 is 1.5h to 6h, and selectively 2h to 5h.

[0050] Adjusting one or more of the second temperature and second time within the above range is advantageous for adjusting the content of disordered carbon in the carbon material to an appropriate range, and the carbon material D / I G This is advantageous in keeping it within an appropriate range, and also in satisfying the requirement that the S2 / S1 ratio of the carbon material is within an appropriate range.

[0051] A third aspect of the present application provides a secondary battery comprising a negative electrode sheet containing the carbon material of the first aspect of the present application or a carbon material manufactured by the method of the second aspect of the present application.

[0052] A fourth aspect of the present application provides a power consumption device including a secondary battery as described in the third aspect of the present application.

[0053] The carbon material according to this application effectively reduces irreversible capacity loss in secondary batteries, improves the capacity performance characteristics of secondary batteries, and enables secondary batteries to possess high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance. The power consumption device according to this application, since it is equipped with the secondary battery according to this application, has at least the same advantages as a secondary battery. [Brief explanation of the drawing]

[0054] To more clearly illustrate the technical concept of the embodiments of this application, the drawings that need to be used in the embodiments of this application are briefly described below. Obviously, the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without requiring any creative work. [Figure 1] This is the Raman spectrum of one embodiment of the carbon material of the present application. [Figure 2] This is a schematic diagram of a cross-sectional image of the carbon material particles of the present invention. [Figure 3] This is a schematic diagram of one embodiment of the secondary battery of the present invention. [Figure 4] This is an exploded schematic diagram of one embodiment of the secondary battery of the present invention. [Figure 5] This is a schematic diagram of one embodiment of the battery module of the present invention. [Figure 6] This is a schematic diagram of one embodiment of the battery pack of the present invention. [Figure 7] Figure 6 is an exploded schematic diagram of an embodiment of the battery pack shown. [Figure 8] This is a schematic diagram of one embodiment of a power consumption device that includes the secondary battery of the present invention as a power source. [Explanation of Symbols]

[0055] The drawings are not always drawn to actual scale. The explanation of the drawing symbols is as follows: 1: Battery pack, 2: Upper housing, 3: Lower housing, 4: Battery module, 5: Rechargeable battery, 51: Case, 52: Electrode assembly, 53: Cover plate, 100: Carbon material, 101: Outer region, 102: Inner region. [Modes for carrying out the invention]

[0056] Hereinafter, with reference to the drawings as appropriate, embodiments specifically disclosing the carbon material of the present application, its manufacturing method, and secondary batteries and power consumption devices using the same will be described in detail. However, some unnecessary details may be omitted. For example, detailed explanations of known matters or redundant explanations of the same structure may be omitted. This is to avoid the following explanation becoming unnecessarily verbose and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following explanation are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0057] The “range” disclosed in this application is limited in the form of a lower limit and an upper limit, and a given range is defined by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundary of a special range. The range thus limited may include or exclude the endpoints, and may be any combination, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are given for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also expected. Also, if the minimum range values ​​1 and 2 and the maximum range values ​​3, 4 and 5 are given, the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 may all be expected. In this application, unless otherwise stated, the numerical range “a-b” is an abbreviation for any combination of real numbers between a and b, and both a and b are real numbers. For example, the numerical range "0 to 5" indicates that in this specification, all real numbers between "0 and 5" are listed, and "0 to 5" is an abbreviated notation for combinations of these numbers. Also, the notation that a parameter is an integer greater than or equal to 2 (≧2) is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0058] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined to form new technical solutions. Such technical solutions are considered to be included in the disclosures of this application.

[0059] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical concepts. Such technical concepts are considered to be included in the disclosures of this application.

[0060] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but it is preferable that they be performed sequentially. For example, if it is stated that the above method includes steps (a) and (b), it means that the above method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if it is stated 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), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0061] Unless otherwise specified, the terms "equipment" and "include" in this application mean open or closed. For example, the terms "equipment" and "include" above may mean further "equipment" or "includes" other components not listed, or "equipment" or "includes" only the listed components.

[0062] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following satisfies the condition "A or B": 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).

[0063] Unless otherwise specified, the terms used in this application have the meanings that are commonly understood by those skilled in the art.

[0064] Unless otherwise specified, the numerical values ​​of each parameter mentioned herein can be measured by various test methods commonly used in the art, for example, according to the test methods provided herein.

[0065] Unless otherwise specified, the term "active ion" in this application refers to an ion that can be reciprocally inserted into and removed from between the positive and negative electrodes of a secondary battery, and includes, but is not limited to, lithium ions.

[0066] In this application, the terms "multiple" and "multiple types" refer to two or more.

[0067] Graphite is classified into artificial graphite and natural graphite depending on the manufacturing process and source. Artificial graphite generally requires a high-temperature graphitization process, which consumes a lot of energy and is therefore costly. Natural graphite, being derived from nature, has the advantage of being relatively inexpensive. It also has the advantage of having a larger capacity.

[0068] Natural graphite mainly consists of flake graphite, natural spheroidal graphite, and microcrystalline graphite. Unlike artificial graphite, natural graphite particles typically have a large number of pores and defects both inside and outside the particles. During the initial charging process of a secondary battery, the electrolyte undergoes numerous side reactions with the particle surface and internal pores, resulting in high initial irreversible capacity loss, low initial Coulomb efficiency, and poor cycle and storage performance. In particular, flake graphite and natural spheroidal graphite have high crystallinity and graphitization, and their microstructure is often layered. This structure causes large volume changes during the desorption and insertion of active ions in natural graphite, making it prone to fragmentation of the graphite layered structure and particle fragmentation. After particle fragmentation, the exposed fresh surface continues to react with the electrolyte, further increasing the irreversible capacity loss of the secondary battery.

[0069] Currently, the performance of natural graphite is primarily improved by coating the particle surface and / or filling the inside of the particles.

[0070] The particle surface coating treatment mainly involves uniformly mixing natural graphite with a coating agent (e.g., pitch, polymer compounds, etc.), followed by heat treatment to coat the surface of the natural graphite particles with a single amorphous carbon layer, lightly repairing defects on the particle surface. However, in the course of investigation, the inventors of this application found that the amorphous carbon layer coated on the surface leads to a decrease in the gram capacity and / or compressive density of the natural graphite, affecting the energy density of the secondary battery. At the same time, the amorphous carbon layer coated on the surface still has many defects on the particle surface, and the amorphous carbon layer coated on the surface does not effectively prevent the electrolyte from penetrating the pore structure inside the particles. As a result, the improvement effect on the initial Coulomb efficiency, cycle performance and / or storage performance of the secondary battery is limited.

[0071] The particle filling process mainly involves mixing natural graphite with a filler (e.g., pitch, polymer compounds, etc.) and filling the pores inside the particles with the filler using methods such as predetermined pressure, vacuum, and heating, to obtain natural graphite without pores inside the particles. However, in the course of investigation, the inventors of this application discovered that the large amount of carbon, especially soft carbon, filling the inside of the particles reduces both the gram capacity and compressive density of the natural graphite, affecting the energy density of the secondary battery. At the same time, because all the pores inside the natural graphite particles are filled with carbon, the volume change that occurs during the desorption and insertion process of active ions in the natural graphite becomes larger, making the particles more prone to fragmentation. Furthermore, the repeated destruction and reconstruction of the SEI film on the particle surface further increases the irreversible consumption of active ions, increasing the irreversible capacity loss of the secondary battery and shortening its service life. In conventional technology, an amorphous carbon layer is continuously applied to the surface of natural graphite, which does not have pores inside the particles. This further reduces the gram capacity and / or compressive density of the natural graphite, and because the surface defects of the particles remain numerous, the lifespan of the secondary battery cannot be effectively improved.

[0072] Therefore, after modifying natural graphite by the above-mentioned coating treatment of the particle surface and / or filling treatment of the particle interior, it is possible to reduce the irreversible capacity loss of the secondary battery to some extent and improve the initial Coulomb efficiency of the secondary battery. However, the improvement in the initial Coulomb efficiency of the secondary battery is limited, and the energy density of the secondary battery is also lost. Furthermore, the capacity performance characteristics during long-term cycles and storage processes of the secondary battery remain poor.

[0073] In light of this, the inventors of the present invention, after extensive research, have provided a new carbon material that combines high gram capacity, high initial Coulomb efficiency, and small volume change, and that can also provide secondary batteries with high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance. Carbon materials

[0074] A first aspect of the embodiments of the present application includes a pore structure, where 0.150 ≤ I D / I G Satisfying ≤ 0.280, I D This is the Raman spectrum of carbon material at 1350±50 cm⁻¹. -1 This represents the D peak intensity at I G This is the Raman spectrum of carbon material at 1580±50 cm⁻¹. -1 This provides a carbon material that represents the G-peak intensity in a given region.

[0075] The carbon material relating to this invention effectively reduces irreversible capacity loss in secondary batteries, improves the capacity performance characteristics of secondary batteries, and enables secondary batteries to possess high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance. The reasons for this include at least the following:

[0076] The carbon material provided in this application includes a pore structure. In this application, "including a pore structure" means that the carbon material has a pore structure that can be directly observed from a cross-sectional image (for example, a scanning electron microscope image at 1000x magnification), that is, the pore structure in the raw material for manufacturing the carbon material is not completely filled. As a result, the pore structure in the carbon material can secure the expansion space necessary for volume changes of the carbon material particles, thereby reducing the risk of new interfaces being generated due to the fragmentation of carbon material particles, and consequently reducing the occurrence of side reactions, reducing irreversible capacity loss of secondary batteries, and improving the cycle performance and storage performance of secondary batteries.

[0077] The carbon material provided in this application is 0.150 ≤ I D / I G It satisfies ≤ 0.280. D / I G This can reflect the degree of disorder on the surface of the carbon material, D / I G The smaller the value, the less disordered carbon is contained on the particle surface of the carbon material, the fewer active sites on the particle surface, and the less irreversible consumption of active ions. However, in the course of their investigation, the inventors of this application found that a lower disordered carbon content is not necessarily better. If the content is too low, both the crystallinity and graphitization of the carbon material become high, which is unfavorable for the rapid desorption and insertion of active ions. At the same time, the volume change of the carbon material becomes large during the charging and discharging process of the secondary battery, which increases the risk of carbon material particle fragmentation. Furthermore, repeated destruction and reconstruction of the SEI film on the particle surface is likely to occur, further increasing the irreversible consumption of active ions, increasing the irreversible capacity loss of the secondary battery, and shortening the service life of the secondary battery. In further investigation, the inventors found that the carbon material is 0.150 ≤ I D / I G We found that satisfying the condition ≤0.280 effectively reduces the content of disordered carbon, lowers the surface activity of the carbon material, and reduces the consumption of active ions due to the formation of SEI films on the particle surface, while also giving the carbon material a stable structure and minimizing particle fragmentation.

[0078] Therefore, the carbon material contains a pore structure and 0.150 ≤ I D / I G When the value ≤0.280 is satisfied, the volume expansion of the carbon material is small, the structural stability is high and the surface activity is low, so it is possible to have a high gram capacity, a high initial Coulomb efficiency and small volume change, and a secondary battery can have a high initial Coulomb efficiency, a high energy density and good cycle performance and storage performance.

[0079] Figure 1 shows the Raman spectrum of one embodiment of the carbon material of the present application. D This is the Raman spectrum of carbon materials at 1350±50 cm⁻¹. -1 This represents the D peak intensity at I G This is the Raman spectrum of carbon materials at 1580±50 cm⁻¹. -1 This represents the G peak intensity in the given region, and in this application, I D / I G This can be expressed as the ratio of the height of the D peak to the height of the G peak in the Raman spectrum.

[0080] In some embodiments, I D / I G This can be a range consisting of 0.155, 0.160, 0.170, 0.180, 0.190, 0.200, 0.210, 0.220, 0.230, 0.240, 0.250, 0.260, 0.270, 0.280, or any of these values. Selectively, 0.152 ≤ I D / I G ≤0.280, 0.152 ≤I D / I G ≤0.260, 0.155 ≤I D / I G ≤0.240, 0.155 ≤I D / I G ≤0.220, 0.155 ≤I D / I G ≤0.200, 0.155 ≤I D / I G The value is ≤0.180. In further investigation, the inventors found that the carbon material I D / I GBy further adjusting within the above range, it has been found that the secondary battery can better have high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0081] In some embodiments, the carbon material includes one or more pore structures with a pore area of 0.15 μm 2 or more, and optionally, one or more pore structures with a pore area of 0.15 μm 2 to 2.0 μm 2 When the carbon material includes a pore structure having the above pore area, the pore structure can ensure an expansion space necessary for the volume change of the carbon material particles, thereby further reducing the risk of generation of a new interface due to crushing of the carbon material particles, and thus reducing the occurrence of side reactions, reducing the irreversible capacity loss of the secondary battery, and improving the cycle performance and storage performance of the secondary battery.

[0082] In some embodiments, the carbon material includes an outer region and an inner region located inside the outer region. The outer region refers to a region formed by extending a distance of 0.25L from the particle surface of the carbon material to the particle interior, where L refers to the short axis length of the carbon material particles. The total pore area of the outer region is denoted as S1, the total pore area of the inner region is denoted as S2, and S2 > S1.

[0083] When the carbon material further satisfies S2 > S1, the carbon material particles further have the characteristics that the number of pores in the inner region is large and / or the pore size is large, while the number of pores in the outer region is small and / or the pore size is small. The pore structure in the internal region of the carbon material can ensure the expansion space required for the volume change of the carbon material particles, thereby reducing the risk of generating new interfaces due to the crushing of the carbon material particles, and thus reducing the occurrence of side reactions, reducing the irreversible capacity loss of the secondary battery, and improving the cycle performance and storage performance of the secondary battery. The small number of pores in the outer region of the carbon material and / or the small pore size can endow the carbon material particles with a more stable structure and avoid the electrolyte from penetrating into the pore structure inside the carbon material particles as much as possible. Thereby, the occurrence of side reactions is reduced, the consumption of active ions due to the formation of the SEI film inside the particles is reduced, and thus the initial Coulomb efficiency of the carbon material is improved, and the cycle performance and storage performance of the secondary battery can be further improved.

[0084] Optionally, 1.5 ≤ S2 / S1 ≤ 450, 2 ≤ S2 / S1 ≤ 400, 2.5 ≤ S2 / S1 ≤ 300, 2.5 ≤ S2 / S1 ≤ 250, 2.5 ≤ S2 / S1 ≤ 200, 2.5 ≤ S2 / Sl ≤ 150, 2.5 ≤ S2 / S1 ≤ 100, 2.5 ≤ S2 / S1 ≤ 50. The inventors have found through further research that when S2 / S1 satisfies the above range, the secondary battery can better have high initial Coulomb efficiency, high energy density, good cycle performance and storage performance.

[0085] In some embodiments, 0.01 μm 2 ≤ S1 ≤ 5.0 μm 2 and optionally, 0.02 μm 2 ≤ S1 ≤ 4.5 μm 2 and 0.03 μm 2 ≤ S1 ≤ 4 μm 2 and 0.04 μm 2 ≤ S1 ≤ 3.5 μm 2 and 0.05 μm 2 ≤ S1 ≤ 3 μm 2 and 0.05 μm 2 ≤ S1 ≤ 2.5 μm2 And, 0.05 μm 2 ≤S1 ≤ 2μm 2 Therefore, if the total pore area of ​​the external region of the carbon material is within the above range, the carbon material particles can be given a more stable structure, and the penetration of the electrolyte into the pore structure inside the carbon material particles can be avoided as much as possible. This reduces the occurrence of side reactions and the consumption of active ions due to the formation of SEI films inside the carbon material particles, while not affecting the transport performance of active ions and electrons.

[0086] In some examples, 2.5 μm 2 ≤S2 ≤ 25.0 μm 2 Therefore, selectively, 3.0 μm 2 ≤S2 ≤ 22.5 μm 2 And, 3.0 μm 2 ≤S2 ≤ 20 μm 2 And, 3.0 μm 2 ≤S2 ≤ 18 μm, and 3.0 μm 2 ≤S2 ≤ 16 μm 2 And, 3.0 μm 2 ≤S2 ≤ 14μm 2 And, 3.0 μm 2 ≤S2 ≤ 12 μm 2 And, 3.0 μm 2 ≤S2 ≤ 10 μm 2 And, 3.0 μm 2 ≤S2 ≤ 8μm 2 Therefore, if the total pore area of ​​the internal region of the carbon material is within the above range, a sufficient and stable expansion space can be secured for volume changes of the carbon material particles, reducing the risk of new interfaces being generated due to the fragmentation of carbon material particles, reducing the occurrence of side reactions on the surface of the new interfaces, and reducing the consumption of active ions due to the formation of SEI films on the surface of the new interfaces, while increasing the capacity of the carbon material and improving the initial Coulomb efficiency.

[0087] In this application, the total pore area S1 of the outer region and the total pore area S2 of the inner region of the carbon material can be obtained by measuring them using a cross-sectional image of the carbon material.

[0088] In this application, the cross-sectional image of the carbon material includes a cross-sectional image passing through the center of the carbon material particle. "Particle center" means the area extending from the geometric center of the particle toward the particle surface within a radius of 0.1 μm.

[0089] In this application, the minor axis length of a particle refers to the minimum value at which the line connecting two points on the surface of the particle passes through the geometric center of the particle.

[0090] Figure 2 is a schematic diagram of a cross-sectional image of a particle of the carbon material 100 of the present invention, and the cross-sectional image passes through the center of the particle of the carbon material 100. As shown in Figure 2, L represents the short axis length of the particle of the carbon material 100, and the region formed by extending a distance of 0.25L from the surface of the particle of the carbon material 100 into the interior of the particle is the outer region 101, and the region inside the outer region 101 is the inner region 102.

[0091] A cross-section of the carbon material can be prepared using a cross-section polisher (e.g., the IB-09010 CP type argon ion cross-section polisher from JEOL Japan Co., Ltd.). Then, referring to JY / T010-1996, the cross-section of the carbon material is scanned using a scanning electron microscope (e.g., the Sigma 300 scanning electron microscope from ZEISS, Germany), and finally, the total pore area S1 of the outer region and the total pore area S2 of the inner region of the carbon material are calculated using image processing software (e.g., AVIZO).

[0092] In some embodiments, the short axis length L of the carbon material particles satisfies L ≥ 4 μm, and selectively, it is 4 μm ≤ L ≤ 25 μm, 4 μm ≤ L ≤ 20 μm, 6 μm ≤ L ≤ 20 μm, 8 μm ≤ L ≤ 20 μm, 8 μm ≤ L ≤ 18 μm, or 8 μm ≤ L ≤ 16 μm.

[0093] In some embodiments, the area of ​​the pore structure in the external region of the carbon material is 0.15 μm or less, and selectively 0.10 μm or less. In further investigation, the inventors found that by controlling the area of ​​the pore structure in the external region of the carbon material to within the above range, a dense structure can be provided in the external region of the carbon material, thereby effectively improving the structural stability of the carbon material, minimizing the penetration of the electrolyte into the pore structure inside the carbon material particles, and consequently effectively improving the cycle performance and storage performance of the secondary battery. Of course, in this application, the area of ​​all pore structures in the external region of the carbon material is 0.15 μm. 2 This does not limit the results to the following; for example, it can be controlled to over 95%, and selectively, the area of ​​the pore structure with over 99% of the pores may be 0.15 μm². 2 The following applies, with selectable 0.10 μm 2 The following applies:

[0094] In some embodiments, the internal region of the carbon material has an area of ​​0.15 μm 2 It includes one or more pore structures, selectively with an area of ​​0.15 μm². 2 ~2.0μm 2 The material includes one or more pore structures. In further investigation, the inventors found that by including pore structures of the above area in the internal region of the carbon material, a sufficient and stable expansion space can be secured for volume changes of the carbon material particles, reducing the risk of fragmentation of the carbon material particles, while increasing the compressive density of the carbon material.

[0095] In some embodiments, the interlayer distance in the outer region of the carbon material is denoted as d1, the interlayer distance in the inner region of the carbon material is denoted as d2, and the carbon material satisfies d1 ≥ d2, and selectively, d1 > d2.

[0096] The large interlayer distance in the outer region of the carbon material is advantageous for the rapid insertion and removal of active ions, thus further improving the dynamic performance of the secondary battery. The small interlayer distance in the inner region of the carbon material is advantageous for increasing the gram capacity and compressive density of the carbon material, thus further increasing the energy density of the secondary battery.

[0097] In some examples, d1 is between 0.33565 nm and 0.33620 nm.

[0098] In some examples, d2 is between 0.33557 nm and 0.33589 nm.

[0099] The interlayer distances in different regions of a carbon material can be measured using known instruments and methods in this field. For example, it can be measured using a high-resolution transmission electron microscope (HRTEM). The test instrument can be a Thermo Fishers Spectra S / TEM scanning transmission electron microscope.

[0100] In some embodiments, the topography of the carbon material includes one or more of the following: lumpy, spherical, and subspherical. This is advantageous for increasing the compressive density of the negative electrode sheet, and consequently, the energy density of the secondary battery.

[0101] In some embodiments, the carbon material contains primary particles, and selectively, the quantity ratio of the primary particles in the carbon material is 50% or more, for example, 55% to 95%, 60% to 100%, 65% to 90%, 65% to 80%, 70% to 100%, 75% to 90%, 80% to 100%, 90% to 100%, or 95% to 100%. When the carbon material contains an appropriate proportion of primary particles, the carbon material can have high structural stability, reduce the occurrence of side reactions, and increase the compressive density of the negative electrode sheet, thereby increasing the energy density of the secondary battery.

[0102] In some embodiments, the carbon material may consist of primary particles, that is, the quantity ratio of primary particles in the carbon material is 100%.

[0103] The terms primary and secondary particles are both known in this field. Primary particles are particles in a non-aggregated state. Secondary particles are particles in an aggregated state, formed by the aggregation of two or more primary particles. Primary and secondary particles can be distinguished using scanning electron microscope (SEM) images.

[0104] In this application, the quantity ratio of primary particles in the carbon material can be measured by the following method: Select one test sample from the negative electrode film layer, select any multiple test areas in the test sample, acquire images of the multiple test areas using a scanning electron microscope, statistically calculate the ratio of the number of carbon material particles in the primary particle topography to the total number of carbon material particles in each image, and the average of the multiple statistical results is the quantity ratio of primary particles in the carbon material.

[0105] In some embodiments, the degree of graphitization of the carbon material is 92.0% to 98.0%, and selectively between 92.5% and 97.6%. Having the degree of graphitization of the carbon material within this range is advantageous for providing secondary batteries with high energy density, good cycle performance, storage performance, and dynamic performance.

[0106] The degree of graphitization of carbon materials is a known concept in this art and can be measured using known instruments and methods in this art. For example, it can be measured using an X-ray diffractometer (e.g., Bruker D8 Discover), and the measurement is performed according to JIS K 0131-1996, JB / T 4220-2011, by measuring the average interlayer distance d of the (002) crystal plane in the crystal structure of the carbon material. 002 Obtain the following equation: g=(0.344-d 002 The degree of graphitization can be calculated based on ) / (0.344-0.3354)×100%. In the above formula, d 002This is the average interlayer distance of the (002) crystal plane in the crystal structure of a carbon material, expressed in nanometers (nm).

[0107] In some embodiments, the specific surface area of ​​the carbon material is 2.1 m². 2 It is less than / g and selectively 0.7m 2 / g~1.8m 2 / g, 0.7m 2 / g~1.7m 2 / g, 0.7m 2 / g~1.6m 2 / g, 0.7m 2 / g~1.5m 2 / g, 0.7m 2 / g~1.4m 2 / g, 0.7m 2 / g~1.3m 2 / g, 0.7m 2 / g~1.25m 2 The value is / g. Since the carbon material of this application has a low specific surface area and low surface activity, it can reduce the consumption of active ions due to the formation of SEI films, improve the initial Coulomb efficiency of the carbon material, and improve the cycle performance and storage performance of secondary batteries.

[0108] The specific surface area of ​​carbon materials has a known meaning in this art and can be measured using known instruments and methods in this art. For example, referring to GB / T 19587-2017, it can be tested using the nitrogen gas adsorption specific surface area analysis method and calculated using the BET (Brunauer Emmett Teller) method. The nitrogen gas adsorption specific surface area analysis test can be performed using the Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, Inc., USA.

[0109] In some embodiments, the volume distribution particle size Dv50 of the carbon material is 6.0 μm to 30.0 μm, and selectively 8.0 μm to 25.0 μm.

[0110] In some embodiments, the volume distribution particle size Dv90 of the carbon material is 16.0 μm to 45.0 μm, and selectively 17.0 μm to 42.0 μm.

[0111] If the volume distribution particle size Dv50 and / or Dv90 of the carbon material is within the above range, it is advantageous for improving the transport performance of active ions and electrons, and thus the cycle performance and dynamic performance of the secondary battery can be further improved.

[0112] In some embodiments, the particle size distribution (Dv90-Dv10) / Dv50 of the carbon material is 1.55 or less, and selectively between 0.5 and 1.50. When the particle size distribution (Dv90-Dv10) / Dv50 of the carbon material is within the above range, it is advantageous to increase the compressive density of the carbon material, which in turn allows for a further increase in the energy density of the secondary battery. It is also advantageous for forming a rational tunnel structure between the particles of the negative electrode film layer, thereby improving the cycle performance and dynamic performance of the secondary battery.

[0113] In this application, the volume distribution particle sizes Dv10, Dv50, and Dv90 of the carbon material have meanings known in the art, representing the particle sizes corresponding to when the cumulative volume distribution percentage of the material reaches 10%, 50%, and 90%, respectively, and can be measured with instruments and methods known in the art. For example, they can be conveniently measured using a laser particle size analyzer, referring to the GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method. The test instrument may be a Mastersizer 3000 laser particle size analyzer from Malvern Instruments Ltd., UK.

[0114] In some embodiments, the powder resistivity of the carbon material under a pressure of 8 MPa is 0.006 Ω·cm to 0.051 Ω·cm, and selectively between 0.010 Ω·cm and 0.040 Ω·cm. Having the powder resistivity of the carbon material within this range is advantageous for improving electron transport performance, and can further enhance the cycle performance and dynamic performance of the secondary battery.

[0115] The powder resistivity of carbon materials is a known concept in the art and can be measured using known instruments and methods in the art. For example, referring to GB / T 30835-2014, it can be measured using the four-probe method with a powder resistivity tester (e.g., Suzhou Crystal ST2722, Sansi Vertical UTM7305). An exemplary measurement method involves weighing a certain amount of sample powder, placing it in a special mold, setting a test pressure, and obtaining powder resistivity at different pressures. In this application, the test pressure may be set to 8 MPa.

[0116] In some embodiments, the powder compression density of the carbon material under a pressure of 20,000 N was 1.70 g / cm³. 3 ~1.95g / cm 3 Therefore, it is selectable to 1.72 g / cm³. 3 ~1.92g / cm 3 Therefore, if the compressed density of the carbon material powder is within the above range, it is possible to increase the compressed density of the negative electrode sheet, further increasing the energy density of the secondary battery. It is also advantageous in improving the transport performance of active ions and electrons, thereby improving the cycle performance and dynamic performance of the secondary battery.

[0117] In this application, the compressed density of carbon material powder is in the known sense of the art and can be measured with instruments and methods known in the art. For example, it can be measured by an electronic pressure tester (for example, a UTM7305 electronic pressure tester) referring to GB / T 24533-2009. An exemplary test method involves weighing 1 g of carbon material powder and measuring the compressed density with a base area of ​​1.327 cm². 2 The material is placed in a mold, pressurized to 2000 kg (equivalent to 20000 N), held for 30 seconds, then the pressure is released and held for 10 seconds. After that, the compressed density of the carbon material powder at a pressure of 20000 N is recorded and calculated.

[0118] In some embodiments, the tap density of the carbon material is 0.80 g / cm³. 3 ~1.35g / cm 3 Therefore, it is selectable to 0.85 g / cm³. 3 ~1.30g / cm 3Therefore, if the tap density of the carbon material is within the above range, the compressive density of the negative electrode sheet can be increased, further increasing the energy density of the secondary battery. This is also advantageous for improving the transport performance of active ions and electrons, as well as the cycle performance and dynamic performance of the secondary battery.

[0119] The tap density of carbon materials is a known concept in this art and can be measured using known instruments and methods in this art. For example, it can be measured using a powder tap density tester, referring to GB / T 5162-2006. The Dandong Baite BT-301 can be used as the test instrument.

[0120] In some embodiments, the gram capacity of the carbon material is 350 mAh / g to 372 mAh / g, and selectively 353 mAh / g to 371 mAh / g. When the gram capacity of the carbon material is within the above range, the energy density of the secondary battery can be increased.

[0121] The gram capacity of carbon materials is a known concept in this art and can be measured by methods known in this art. An exemplary test method involves thoroughly mixing a carbon material sample with a binder (styrene-butadiene rubber, SBR), a thickener (carboxymethylcellulose sodium, CMC), and a conductive agent (carbon black) in a mass ratio of 96.2:1.8:1.2:0.8 with an appropriate amount of deionized water as a solvent to form a uniform negative electrode slurry. This slurry is then uniformly applied to the surface of a copper foil negative electrode current collector and dried in an oven before use. Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. LiPF6 is then dissolved in the organic solvent to prepare an electrolyte with a concentration of 1 mol / L. Subsequently, a CR2430 type coin cell is assembled in a glove box protected by argon gas, using a metallic lithium sheet as the counter electrode and a polyethylene (PE) film as the separator. At 25°C, the fabricated coin cell was first discharged with a constant current of 0.15mA to 0.005V, left to stand for 5 minutes, and then discharged again with a constant current of 10μA to 0.005V to record the initial discharge capacity of the coin cell. Subsequently, it was charged with a constant current of 0.3mA to 2.0V to record the charging capacity of the coin cell. The ratio of the charging capacity of the coin cell to the mass of the carbon material sample is the gram capacity of the carbon material. Manufacturing method

[0122] A second embodiment of the present invention provides a method for manufacturing a carbon material that can produce the carbon material of the first embodiment of the present invention.

[0123] The method for producing the carbon material comprises: step 1 providing a raw material having a plurality of pore structures; step 2 uniformly mixing the raw material and a filler in a predetermined ratio, then maintaining the mixture at a first temperature T1 for a first time t1 to obtain an intermediate; and step 3 maintaining the obtained intermediate at a second temperature T2 for a second time t2 to obtain a carbon material, wherein the carbon material contains pore structures, and the carbon material has a density of 0.150 ≤ I D / I G Satisfying ≤ 0.280, I DThis is the Raman spectrum of the carbon material at 1350±50 cm⁻¹. -1 This represents the D peak intensity at I G This is the Raman spectrum of the carbon material at 1580±50 cm⁻¹. -1 This represents the G-peak intensity in that region.

[0124] In some embodiments, the raw materials for producing the carbon material include natural graphite. Optionally, the natural graphite includes one or more of the following: flake graphite, natural spheroidal graphite, and microcrystalline graphite, and more optionally, natural spheroidal graphite.

[0125] "Natural spheroidal graphite" refers to natural graphite that is spherical or near-spheroidal, and does not mean that all natural graphite particles are controlled to be ideal spheres. In some examples, natural spheroidal graphite with a desired particle size and topography can be obtained by pretreatment of flake graphite, and selectively, the pretreatment includes steps such as crushing, classification, spheroidization, and purification.

[0126] In some embodiments, the topography of the raw material includes one or more types of spherical or subspherical shapes.

[0127] In some examples, the volume distribution particle size Dv50 of the raw material is 6.0 μm to 30.0 μm, and selectively 8.0 μm to 25.0 μm.

[0128] In some examples, the specific surface area of ​​the raw material is 2.5 m². 2 It is 2.5m or more and can be selected. 2 / g~10.0m 2 The value is / g. If the specific surface area of ​​the raw material is within the above range, it is advantageous for subsequent filling processes to obtain a carbon material with the desired specific surface area, it is also advantageous for the carbon material to have high capacity and high initial Coulomb efficiency, and it is also advantageous for the carbon material to have better dynamic performance.

[0129] By adjusting the particle size of the raw material (e.g., volume-distributed particle size Dv50 and / or specific surface area) within the above range, aggregation of the raw material during subsequent manufacturing processes can be avoided as much as possible, thereby minimizing problems such as an increase in surface defects due to particle fragmentation and an increase in surface-active sites.

[0130] In some embodiments, the volume distribution particle size Dv50 of the filler is 6 μm or less, and is selectively 1 μm to 6 μm, 1 μm to 5 μm, 2 μm to 5 μm, or 3 μm to 5 μm. This is advantageous for the filler to fill the pore structure of the raw material after melting due to heat, and is also advantageous for improving the uniformity of dispersion between the filler and the raw material.

[0131] In some embodiments, the softening point temperature of the filler is 100°C to 180°C. For example, the softening point temperature of the filler may be within the range of 100°C, 110°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, or any of the above values. Selectively, the softening point temperature of the filler may be 100°C to 160°C, 100°C to 150°C, 100°C to 140°C, 110°C to 180°C, 110°C to 170°C, 110°C to 160°C, 110°C to 150°C, 110°C to 140°C, 120°C to 180°C, 120°C to 170°C, 120°C to 160°C, 120°C to 150°C, 120°C to 140°C, 125°C to 180°C, 125°C to 170°C, 130°C to 160°C, 130°C to 150°C, or 130°C to 140°C.

[0132] During their investigation, the inventors found that having the softening point temperature of the filler within the above range is advantageous for adjusting the number and / or size of pores in the external and internal regions of the carbon material to an appropriate range. Furthermore, if the softening point temperature of the filler is too high, the filler will not easily flow into and fill the pore structure of the raw material after melting due to heat, thereby preventing effective modification of internal particle defects and effectively preventing the electrolyte from penetrating the pore structure inside the obtained carbon material particles. This also affects the initial Coulomb efficiency, cycle performance, and storage performance of the secondary battery. Conversely, if the softening point temperature of the filler is too low, the filler contains many small molecular substances, which are easily volatile due to heat. Although the filler will easily flow into and fill the pore structure of the raw material after melting due to heat, heat treatment in step 2 and / or step 3 causes the small molecular substances in the filler to volatilize, preventing the carbon that actually remains in the filling region from effectively filling the pore structure of the raw material, thus failing to achieve an effective filling effect. Alternatively, the carbon that actually remains in the filling region may have many pore structures, and furthermore, the consumption of active ions due to the formation of the SEI film cannot be reduced. This effectively avoids situations where irreversible capacity loss of the secondary battery is reduced, as well as affecting the cycle performance and storage performance of the secondary battery.

[0133] In some embodiments, the coke content of the filler is 25% to 50%, and selectively 30% to 42%. In the course of their investigation, the inventors found that having the coke content of the filler within the above range is advantageous for adjusting the number and / or size of pores in the external and internal regions of the carbon material to an appropriate range.

[0134] In some embodiments, the filler simultaneously satisfies the conditions of having a softening point temperature of 120°C to 160°C and a coke value of 30% to 42%.

[0135] In this application, the coke value of the filler has a meaning known in the art and can be measured with instruments and methods known in the art. For example, it can be measured by referring to GB / T 8727-2008.

[0136] In some embodiments, the filler includes one or more of coal pitch, petroleum pitch, polymer compounds, and resins, and optionally includes one or more of coal pitch and petroleum pitch.

[0137] In some embodiments, the mass ratio of the filler to the raw material is (10-32):100, and selectively (12-30):100, (14-28):100, and (15-25):100. This is advantageous for adjusting the number and / or size of pores in the outer and inner regions of the carbon material to an appropriate range. Furthermore, if the mass ratio of the filler to the raw material is too small, the dispersion uniformity between the filler and the raw material is poor. In this case, the filler does not easily flow and fill the pore structure of the raw material after melting due to heat, which prevents effective modification of internal particle defects and prevents the electrolyte from penetrating the pore structure inside the resulting carbon material particles, affecting the initial Coulomb efficiency, cycle performance, and storage performance of the secondary battery. Conversely, if the mass ratio of the filler to the raw material is too large, it is easy for the pore structure inside the raw material to be completely filled. In this case, the volume change of the resulting carbon material is large, the particles are more easily crushed, the consumption of active ions due to the formation of the SEI film increases, and the irreversible capacity loss of the secondary battery increases. Also, if the mass ratio of the filler to the raw material is too large, there is a possibility that a large amount of filler will remain on the particle surface. In this case, the particles are more likely to aggregate, not only increasing the depolymerization process but also effectively avoiding a decrease in the gram capacity and compressive density of the resulting carbon material.

[0138] By adjusting parameters such as the type of filler, softening point, coke value, and amount of additive within the above range, the filler, after melting due to heat, does not have high viscosity and maintains good fluidity. Furthermore, it reduces the adhesion of raw material particles and the aggregation of raw material particles in subsequent manufacturing processes. This reduces problems such as an increase in surface defects and surface active sites of carbon material particles due to the depolymerization process.

[0139] In some embodiments, in step 2, the heating step, in which the raw materials and the filler are uniformly mixed in a predetermined ratio and then heated to a first temperature T1, is a stepwise heating step and optionally includes a first heating step, a second heating step, and a third heating step.

[0140] In some embodiments, the first heating step involves raising the temperature to 200°C to 250°C and maintaining the temperature at that temperature for 1 to 2 hours.

[0141] In some embodiments, the second heating step involves raising the temperature to 450°C to 550°C and maintaining the temperature at that temperature for 1 to 2 hours.

[0142] In some embodiments, the third heating step involves raising the temperature to the first temperature T1 and maintaining that temperature for a first time t1.

[0143] In the stepwise heating process, the temperature is first raised to 200°C to 250°C. Since the heating temperature is higher than the softening point of the filler, the filler melts and softens due to the heat, and can be held at this temperature for 1 to 2 hours to allow it to flow and fill the pore structure of the raw material. Subsequently, the temperature is raised to 450°C to 550°C. At this point, the melted and softened filler undergoes a carbonization reaction, gradually becoming a charred state and turning into a viscous liquid or solid. This prevents the filler from entering all the pore structures of the raw material. Finally, the temperature is raised to the first temperature. At this point, the filler undergoes a carbonization reaction, which effectively fills the pore structures occupied by the filler.

[0144] In some embodiments, in step 2, the temperature is raised to the first temperature T1 at a rate of 1°C / min to 10°C / min. For example, the heating rate may be in the range of 1°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any value above.

[0145] During their investigation, the inventors found that when the heating rate is within the above range, it is advantageous for adjusting the number and / or size of pores in the external and internal regions of the carbon material to an appropriate range.

[0146] In some embodiments, the heating rate of the first heating step may be 1°C / min to 10°C / min.

[0147] In some embodiments, the heating rate of the second heating step may be 1°C / min to 10°C / min.

[0148] In some embodiments, the heating rate of the third heating step may be 1°C / min to 10°C / min.

[0149] In some embodiments, in step 2, the first temperature T1 is 700°C to 1200°C. For example, the first temperature T1 may be in the range of 700°C, 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C, 1200°C, or any number above. Selectively, the first temperature T1 is 720°C to 1100°C.

[0150] During their investigation, the inventors found that when the first temperature is within the above range, it is advantageous for adjusting the number and / or size of pores in the external and internal regions of the carbon material to an appropriate range. Furthermore, if the first temperature is too low, the filler material may not be completely converted to carbon, and subsequently, during the heat treatment in step 3, it may continue to decompose into small molecular substances. As a result, the carbon that actually remains in the filler region will have a large number of pore structures and will not be able to effectively modify defects inside the particles, nor will it be able to effectively prevent the electrolyte from penetrating the pore structure inside the resulting carbon material particles, thus affecting the initial Coulomb efficiency, cycle performance, and storage performance of the secondary battery. Conversely, if the first temperature is too high, it is possible to effectively avoid a situation where energy consumption in the manufacturing process of the carbon material increases.

[0151] In some embodiments, the first time t1 is between 1h and 5h. For example, the first time t1 may be in the range of 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, or any of these values. Selectively, the first time t1 is between 2h and 4h.

[0152] During their investigation, the inventors found that when the first time falls within the above range, it is advantageous for adjusting the number and / or size of pores in the external and internal regions of the carbon material to an appropriate range. Furthermore, if the first time is too short, the filler cannot effectively fill the carbon material particles, resulting in the carbon that actually remains in the filling region having many pore structures and failing to effectively modify defects inside the particles. This also fails to effectively prevent the electrolyte from penetrating the pore structures inside the resulting carbon material particles, affecting the initial Coulomb efficiency, cycle performance, and storage performance of the secondary battery. Conversely, if the first time is too long, it is possible to effectively avoid a situation where energy consumption in the carbon material manufacturing process increases.

[0153] In some embodiments, in step 2, the heat treatment may be carried out in an intermediate frequency furnace, a roller hearth kiln, a rotary kiln, or a pusher kiln.

[0154] In some embodiments, in step 2, the heat treatment atmosphere may be a protective gas atmosphere. The protective gas may include one or more of nitrogen gas, argon gas, and helium gas.

[0155] In step 2, adjusting one or more of the heating rate, first temperature, first time, heating process, etc., within the above range is advantageous for producing a carbon material having the desired structure. For example, it is advantageous for the carbon material to satisfy S2 > S1, and selectively satisfy 1.5 ≤ S2 / S1 ≤ 450 and 2 ≤ S2 / S1 ≤ 400.

[0156] In some embodiments, the second temperature T2 is between 1800°C and 2600°C. For example, the second temperature may be within a range of 1800°C, 1900°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, 2500°C, 2600°C, or any of the above values. Selectively, the second temperature T2 is 1860°C~2560°C, 1860°C~2520°C, 1860°C~2480°C, 1860°C~2450°C, 1860°C~2410°C, 1860°C~2370°C, 1860°C~2330°C, 1900°C~2560°C, 1900°C~2520°C, 1900°C~2480°C, 1900°C~2450°C, 1900°C~2410°C, 1900°C~2370°C, 1900 The temperature ranges are ℃~2330℃, 1970℃~2560℃, 1970℃~2520℃, 1970℃~2480℃, 1970℃~2450℃, 1970℃~2410℃, 1970℃~2370℃, 1970℃~2330℃, 2030℃~2560℃, 2030℃~2520℃, 2030℃~2480℃, 2030℃~2450℃, 2030℃~2410℃, 2030℃~2370℃, and 2030℃~2330℃.

[0157] During their investigation, the inventors found that when the second temperature is within the above range, it is advantageous for adjusting the degree of disorder in the carbon material, resulting in a stable structure for the carbon material and minimizing particle fragmentation. They further discovered that if the second temperature is too low, the resulting carbon material contains a large amount of disordered carbon, leading to a high defect content, particularly surface defects, which affects the initial Coulomb efficiency and storage performance of the carbon material. Conversely, if the second temperature is too high, the resulting carbon material contains too little disordered carbon, resulting in high crystallinity and graphitization. This is unfavorable for the rapid desorption and insertion of active ions, and the large volume change of the carbon material during the charge-discharge process increases the risk of carbon particle fragmentation, thus effectively avoiding situations that affect the cycle performance and storage performance of the secondary battery.

[0158] In some embodiments, the second time t2 is between 1.5h and 6h. For example, the second time t1 may be in the range of 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, or any of the above values. Selectively, the second time t2 is between 2h and 5h.

[0159] During their investigation, the inventors found that when the second time falls within the above range, it is advantageous for adjusting the degree of disorder in the carbon material, resulting in a stable structure for the carbon material and minimizing particle fragmentation. They further discovered that if the second time is too short, the resulting carbon material contains a large amount of disordered carbon, leading to a high defect content, particularly surface defects, which affects the gram capacity and initial Coulomb efficiency of the carbon material. Conversely, if the second time is too long, the resulting carbon material contains too little disordered carbon, resulting in high crystallinity and graphitization. In this case, it is disadvantageous for the rapid desorption and insertion of active ions, and the large volume change of the carbon material during the charge-discharge process increases the risk of carbon particle fragmentation, thus effectively avoiding situations that affect the cycle performance and storage performance of the secondary battery.

[0160] In some embodiments, in step 3, the heat treatment can be carried out in an intermediate frequency furnace, a box-type graphitizing furnace, an Acheson-type graphitizing furnace, a continuous graphitizing furnace, or an internal series graphitizing furnace.

[0161] In some embodiments, in step 3, the atmosphere for the intermediate frequency furnace and continuous graphitization heat treatment may be a protective gas atmosphere. The protective gas may include one or more of nitrogen gas, argon gas, and helium gas.

[0162] By adjusting one or more of the second temperature and second time within the above range, it is advantageous to adjust the content of disordered carbon in the carbon material to an appropriate range, and the carbon material D / I GThis is advantageous in keeping the ratio within an appropriate range, and also in ensuring that the S2 / S1 ratio of the carbon material is within an appropriate range.

[0163] The carbon material manufacturing method of this invention is simple, highly safe, does not require a predetermined pressure or vacuum treatment, and does not require an additional depolymerization step in the heat treatment process. The carbon material manufactured in this invention has low volume expansion, high structural stability, low surface activity, and can also combine high gram capacity, high initial Coulomb efficiency, and small volume change, and can provide secondary batteries with high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0164] The manufacturing method of this invention is low-cost, highly practical, and suitable for large-scale production. secondary battery

[0165] A third aspect of the embodiments of the present invention provides a secondary battery.

[0166] This application does not particularly limit the type of secondary battery; for example, the secondary battery may be a lithium-ion battery. Typically, a secondary battery includes a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the charging and discharging process of the secondary battery, active ions are reciprocally inserted into and removed from the positive electrode sheet and the negative electrode sheet, and the electrolyte plays a role in conducting the active ions between the positive electrode sheet and the negative electrode sheet. This application does not particularly limit the type of electrolyte, and it can be selected according to actual needs. For example, the electrolyte may be at least one type selected from a solid electrolyte and a liquid electrolyte (i.e., an electrolyte solution). A secondary battery using an electrolyte solution and a secondary battery using a solid electrolyte may further include a separator that serves to isolate the positive electrode sheet and the negative electrode sheet. [Negative electrode sheet]

[0167] 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. For example, the negative electrode current collector has two opposing surfaces in the direction of its own thickness, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0168] In some embodiments, the negative electrode film layer includes a carbon material according to the first embodiment of the present invention or a carbon material manufactured by the method described in the second embodiment of the present invention. This enables the secondary battery to have high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0169] In some embodiments, the negative electrode film layer may further contain other negative electrode active materials besides the carbon material described above. In some embodiments, the other negative electrode active materials include, but are not limited to, one or more of the following: conventional natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based material may include one or more of the following: elemental silicon, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. The tin-based material may include one or more of the following: elemental tin, tin oxide, and tin alloy material.

[0170] In some embodiments, the negative electrode film layer may optionally further contain a negative electrode conductive agent. The type of negative electrode conductive agent is not particularly limited in this application, and as an example, the negative electrode conductive agent may include one or more of the following: superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0171] In some embodiments, the negative electrode film layer may optionally further contain a negative electrode binder. The present application does not particularly limit the type of the negative electrode binder, and for example, the negative electrode binder may contain one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (e.g., polyacrylate PAA, polymethacrylate PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0172] In some embodiments, the negative electrode film layer may optionally further contain other additives. For example, the other additives may include, for instance, a thickener such as sodium carboxymethylcellulose (CMC) or a PTC thermistor material.

[0173] In some embodiments, the negative electrode current collector can be a metal foil sheet or a composite current collector. Copper foil can be used as an example of a metal foil sheet. The composite current collector may include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. For example, the metal material may include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer material substrate may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0174] The negative electrode film layer is typically formed by applying a negative electrode slurry to a negative electrode current collector, drying, and cold pressing. The negative electrode slurry is typically formed by dispersing a negative electrode active material, a selectable conductive agent, a selectable binder, and a selectable other auxiliary agent in a solvent and stirring uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0175] The negative electrode sheet does not exclude any additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet according to the present invention further includes a conductive undercoat layer (e.g., consisting of a conductive agent and a binder) sandwiched between the negative electrode current collector and the negative electrode film layer and provided on the surface of the negative electrode current collector, and in some embodiments, the negative electrode sheet according to the present invention further includes a protective layer covering the surface of the negative electrode film layer. [Positive electrode sheet]

[0176] 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. For example, the positive electrode current collector has two opposing surfaces in the direction of its own thickness, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0177] The positive electrode current collector can be a metal foil sheet or a composite current collector. An example of a metal foil sheet is aluminum foil. The composite current collector can 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 types from aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer material base layer may include one or more types from polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0178] The positive electrode film layer typically comprises a positive electrode active material, a selectable binder, and a selectable conductive agent. The positive electrode film layer is typically formed by applying a positive electrode slurry to the positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, a selectable conductive agent, a selectable binder, and other selectable components in a solvent and stirring uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP). For example, the binder used in the positive electrode film layer may include one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a ternary copolymer of vinylidene fluoride-tetrafluoroethylene-propylene, a ternary copolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, and a fluorine-containing acrylate resin. For example, the conductive agent used in the positive electrode film layer includes one or more of the following: superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0179] The positive electrode active material can be a known positive electrode active material for secondary batteries in this field.

[0180] When the secondary battery of the present application is a lithium ion battery, the positive electrode active material includes, but is not limited to, one or more of lithium-containing transition metal oxides, lithium-containing phosphates, and their modified compounds. Examples of the lithium transition metal oxides include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of the lithium-containing phosphates include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their modified compounds.

[0181] In some embodiments, in order to further improve the energy density of the secondary battery, the positive electrode active material used in the lithium ion battery may include one or more of lithium transition metal oxides and their modified compounds having the general formula Li a Ni b Co c M d O e A f where 0.8 ≦ a ≦ 1.2, 0.5 ≦ b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M is one or more selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is one or more selected from N, F, S, and Cl.

[0182] In some embodiments, for example, the positive electrode active material for the lithium ion battery is LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3O2 (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 It may contain one or more of the following: O2, LiFePO4, and LiMnPO4.

[0183] In this application, the modified compounds for each of the above-mentioned positive electrode active materials are obtained by performing doping modification and / or surface coating modification on the positive electrode active material. [Electrolyte]

[0184] In some embodiments, the electrolyte is an electrolyte solution containing an electrolyte salt and a solvent.

[0185] The type of electrolyte salt is not specifically limited and can be selected according to actual demand.

[0186] If the secondary battery of the present application is a lithium-ion battery, the electrolyte salt may, for example, include one or more of the following: lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium difluorosulfonylimide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium disoxalate borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodisoxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0187] The type of solvent is not particularly limited and can be selected according to actual demand. In some examples, the organic solvent may include, for instance, one or more of the following: 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).

[0188] In some embodiments, the electrolyte may optionally further contain additives. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performance characteristics of the secondary battery, such as additives that improve the overcharge performance of the secondary battery, additives that improve the high-temperature performance of the secondary battery, and additives that improve the low-temperature output performance of the secondary battery. [Separator]

[0189] In this application, the type of separator is not particularly limited, and any known porous structure separator having good chemical and mechanical stability can be selected.

[0190] In some embodiments, the separator material may include one or more of the following: glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film. If the separator is a multilayer composite film, the materials of each layer may be the same or different.

[0191] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet can be manufactured into an electrode assembly by a winding process or a lamination process.

[0192] In some embodiments, the secondary battery may include an outer casing. This casing is used to seal the electrode assembly and electrolyte described above.

[0193] In some embodiments, the outer packaging may be a hard case such as a rigid plastic case, an aluminum case, or a steel case. The outer packaging may also be a soft bag, such as a bag soft bag. The material of the soft package may be plastic, and may be one or more of the following: polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0194] The shape of the secondary battery of this application is not particularly limited and may be cylindrical, rectangular, or any other shape. Figure 3 shows a rectangular secondary battery 5 as an example.

[0195] In some embodiments, as shown in Figure 4, the exterior may include a case 51 and a cover plate 53. The case 51 includes a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates enclose a housing chamber. The case 51 has an opening that communicates with the housing chamber, and the cover plate 53 closes the opening so as to close the housing chamber. The positive electrode sheet, negative electrode sheet and separator can be formed into an electrode assembly 52 by a winding or lamination process. The electrode assembly 52 is packaged into the housing chamber. The electrolyte permeates the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more and may be adjusted according to demand.

[0196] The method for manufacturing the secondary battery of the present invention 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. For example, an electrode assembly can be formed by winding or laminating a positive electrode sheet, a separator, and a negative electrode sheet, the electrode assembly can be placed in an outer casing, dried, and then the electrolyte can be injected. A secondary battery can then be obtained by going through processes such as vacuum sealing, standing, chemical formation, and shaping.

[0197] In some embodiments of the present invention, the secondary battery may be assembled into a battery module, and the number of secondary batteries included in the battery module may be multiple, and the specific number may be adjusted according to the application and capacity of the battery module.

[0198] Figure 5 is a schematic diagram of a battery module 4 as an example. As shown in Figure 5, in the battery module 4, the multiple secondary batteries 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple secondary batteries 5 may be fixed together with fasteners.

[0199] Optionally, the battery module 4 further includes an external case having a housing space, and multiple secondary batteries 5 are housed in the housing space.

[0200] In some embodiments, the battery modules may be assembled as a battery pack, and the number of battery modules included in the battery pack may be adjusted according to the application and capacity of the battery pack.

[0201] Figures 6 and 7 are schematic diagrams of an example battery pack 1. As shown in Figures 6 and 7, the battery pack 1 may include a battery housing and a plurality of battery modules 4 provided in the battery housing. The battery housing includes an upper housing 2 and a lower housing 3, with the upper housing 2 covering the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery housing in any manner. power consumption equipment

[0202] The present application further provides a power consumption device comprising at least one of the secondary battery, battery module, or battery pack of the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device or as an energy storage means for the power consumption device. The power consumption device may be, but is not limited to, mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), trains, ships, and satellites, energy storage systems, etc.

[0203] The aforementioned power consumption device can select a secondary battery, battery module, or battery pack depending on the demand.

[0204] Figure 8 is a schematic diagram of an example of a power consumption device. This power consumption device includes pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, etc. To meet the high power and high energy density requirements of this power consumption device, a battery pack or battery module can be used.

[0205] Other examples of power-consuming devices may include mobile phones, tablet computers, and laptop computers. These power-consuming devices generally require a thin design and can utilize rechargeable batteries as their power source. Examples

[0206] The following examples illustrate the contents of this application in more detail, but these examples are merely illustrative, and it will be apparent to those skilled in the art that various modifications and changes can be made within the scope of the disclosure. Unless otherwise specified, all parts, percentages, and ratios described in the following examples are based on mass. Furthermore, all reagents used in the examples may be commercially available or synthesized according to conventional methods, and may be used as is without requiring further processing. Furthermore, all apparatus used in the examples may be commercially available. Example 1 (1) Preparation of carbon materials

[0207] Step 1: Mechanical grinding, classification, spheroidization, and purification treatment are performed on 100-mesh flake graphite to obtain a volume distribution particle size Dv50 of 11 μm and a BET specific surface area of ​​7 m². 2 Natural spheroidal graphite was obtained at a concentration of / g.

[0208] Step 2: The obtained natural spheroidal graphite and petroleum pitch (softening point temperature of 148°C, volume distribution particle size Dv50 of 4.5 μm, coke value of 40%) were mixed in a VC mixer at a mass ratio of 100:20 for 30 minutes. The mixed material was then placed in a roller hearth kiln and heated to 220°C at a rate of 5°C / min and held for 1 hour (first heating step). Subsequently, the temperature was raised to 500°C at a rate of 5°C / min and held for 2 hours (second heating step). Finally, the temperature was raised to 1000°C at a rate of 5°C / min and held for 2 hours (third heating step). After completion, the mixture was cooled to room temperature to obtain an intermediate.

[0209] Step 3: The obtained intermediate was placed in an Acheson-type graphitization furnace, heated to 2400°C and maintained for 2 hours. After completion, it was demagnetized and sieved to obtain the carbon material.

[0210] Referring to GB / T 19587-2017, the specific surface area of ​​the carbon material was measured using the nitrogen gas adsorption specific surface area analysis method, and the specific surface area was calculated using the BET (Brunauer Emmett Teller) method, resulting in a value of 1.07 m². 2It was / g. The test equipment may be a Tri-Star 3020 specific surface area and pore size analyzer manufactured by Micromeritics, USA.

[0211] Referring to GB / T 30835-2014, the powder resistivity of the carbon material was measured by a four-probe method using a powder resistivity tester. The powder resistivity of the obtained carbon material at a pressure of 8 MPa was 0.0110 Ω·cm. The test equipment may be a Suzhou Lattice ST2722 powder resistivity tester.

[0212] Referring to JIS K 0131-1996 and JB / T 4220-2011, the average interlayer distance d of the (002) crystal plane in the crystal structure of the carbon material 002 was obtained, and then the graphitization degree of 97.3% of the carbon material was calculated by the formula g = (0.344 - d 002 ) / (0.344 - 0.3354) × 100%. The test equipment may be a Bruker D8 Discover X-ray diffractometer. (2). Manufacture of coin cell (half cell)

[0213] The carbon material manufactured above, styrene-butadiene rubber (SBR) as a binder, sodium carboxymethyl cellulose (CMC) as a thickener, and carbon black as a conductive agent were sufficiently stirred and mixed with deionized water, an appropriate amount of solvent, at a mass ratio of 96.2:1.8:1.2:0.8 to form a uniform negative electrode slurry. The negative electrode slurry was uniformly coated on the surface of a copper foil, which is a negative electrode current collector, and dried in an oven for preparation. After ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) were mixed at a volume ratio of 1:1:1 to obtain an organic solvent, LiPF6 was dissolved in the above organic solvent to prepare an electrolyte with a concentration of 1 mol / L. Then, a CR2430 coin cell was assembled in a glove box protected by argon gas with a metal lithium sheet as the counter electrode and a polyethylene (PE) film as the separator. (3). Manufacture of secondary battery (full cell)

[0214] The carbon material produced above, carbon black (Super P) as a conductive agent, styrene-butadiene rubber as a binder, and sodium carboxymethyl cellulose as a thickener were sufficiently stirred and mixed in deionized water, which is an appropriate amount of solvent, at a weight ratio of 96:1:1:2 to form a negative electrode slurry. The negative electrode slurry was applied to two surfaces of a copper foil, which is a negative electrode current collector, dried, and cold-pressed to obtain a negative electrode sheet.

[0215] LiFePO4, conductive carbon black, and polyvinylidene fluoride were mixed at a weight ratio of 96:2.5:1.5, an appropriate amount of solvent NMP was added, and the mixture was uniformly stirred to obtain a positive electrode slurry. The positive electrode slurry was applied to two surfaces of an aluminum foil, which is a positive electrode current collector, dried, and cold-pressed to obtain a positive electrode sheet.

[0216] A polypropylene film with a thickness of 12 μm was used as a separator, and the positive electrode sheet and the negative electrode sheet produced above were arranged in order. The separator was located between the positive electrode sheet and the negative electrode sheet to perform an isolation function. Then, it was wound to obtain an electrode assembly. The electrode assembly was placed in an outer package, dried, and the same electrolyte as the coin cell produced above was injected. After passing through processes such as vacuum sealing, standing, forming, and capacity, a secondary battery was obtained. Comparative Example 1

[0217] The manufacturing methods of the half cell and the full cell are similar to those of Example 1 except for the manufacturing process of the carbon material.

[0218] 100-mesh flaky graphite was mechanically pulverized, classified, spheroidized, and purified to obtain natural spherical graphite with a volume distribution particle size Dv50 of 11 μm and a BET specific surface area of 7 m 2 / g. After that, the obtained natural spherical graphite was used as a carbon material to manufacture a half cell and a full cell. Comparative Example 2

[0219] The manufacturing methods of the half cell and the full cell are similar to those of Example 1 except for the manufacturing process of the carbon material.

[0220] 100-mesh flake graphite was mechanically crushed, classified, spheroidized, and purified, resulting in a volume distribution particle size Dv50 of 11 μm and a BET specific surface area of ​​7 m². 2 Natural spheroidal graphite was obtained in a quantity of / g. The obtained natural spheroidal graphite and petroleum pitch (softening point temperature 148°C, volume distribution particle size Dv50 4.5 μm, coke value 40%) were mixed in a VC mixer at a mass ratio of 100:20 for 30 minutes. The mixed material was then graphitized at 3200°C for 10 hours, and after completion, it was cooled to room temperature to obtain carbon material. Comparative Example 3

[0221] The manufacturing methods for half-cells and full-cells are similar to those in Example 1, except for the carbon material manufacturing process.

[0222] 100-mesh flake graphite was mechanically crushed, classified, spheroidized, and purified to obtain a volume distribution particle size Dv50 of 11 μm and a BET specific surface area of ​​7 m². 2 Natural spheroidal graphite was obtained at a concentration of / g. The obtained natural spheroidal graphite and petroleum pitch (softening point temperature 148°C, volume distribution particle size Dv50 4.5 μm, coke value 40%) were mixed in a VC mixer at a mass ratio of 100:20 for 30 minutes. The mixed material was then carbonized at 1300°C for 2 hours, and after completion, it was cooled to room temperature to obtain a carbon material. Comparative Example 4

[0223] The manufacturing methods for half-cells and full-cells are similar to those in Example 1, except for the carbon material manufacturing process.

[0224] Raw graphite ore was processed into small particles by mechanical treatment. To remove impurities, it was treated with a strong alkaline solution and a strong acid solution at high temperature. After washing and drying at high temperature, it was sieved to extract plate-shaped natural graphite. To make the plate-shaped natural graphite spherical, primary and secondary polishing, i.e., mechanical processing, was performed. Next, after acid treatment, washing, drying, and purification, high-purity spherical natural graphite was obtained. The obtained spherical natural graphite suffered surface damage during mechanical crushing and grinding, and chemically reactive groups were formed after strong alkaline / strong acid washing. Defects occurred in the natural graphite due to mechanical processing during spheroidization. For carbon coating, pitch (softening point temperature 148°C, volume distribution particle size Dv50 4.5 μm, coke value 40%) was solid-phase coated onto the surface of the damaged high-purity solid-phase natural graphite by a dry method, and carbonization was performed at 1200°C for 24 hours in an inert gas atmosphere to obtain carbon coating. After crushing, sieving, and iron removal, carbon material was obtained. Comparative Example 5

[0225] The manufacturing methods for half-cells and full-cells are similar to those in Example 1, except for the carbon material manufacturing process.

[0226] 100-mesh flake graphite was mechanically crushed, classified, spheroidized, and purified to obtain a volume distribution particle size Dv50 of 11 μm and a BET specific surface area of ​​7 m². 2 Natural spheroidal graphite was obtained at a concentration of / g. The obtained natural spheroidal graphite was mixed with powdered medium-temperature pitch (containing 1% quinoline-insoluble matter, with a softening point of 80°C) and toluene, which accounted for 0.5% of the pitch's mass, in a 1:1 mass ratio. The mixture was then placed in a reaction vessel, sealed, and heated to 200°C at a rate of 3°C / min. The mixture was kept at a constant temperature for 4 hours, maintaining a pressure of 0.1 MPa. After that, the sample was removed, cooled, and then graphitized in a furnace at 3000°C. The graphitized sample was pulverized and classified to obtain carbon material. Comparative Example 6

[0227] The manufacturing methods for half-cells and full-cells are similar to those in Example 1, except for the carbon material manufacturing process.

[0228] The flaky graphite with 100 meshes was mechanically pulverized, classified, spheroidized, and purified to obtain natural spherical graphite with a volume distribution particle size Dv50 of 11 μm and a BET specific surface area of 7 m 2 / g.

[0229] The obtained natural spherical graphite and petroleum pitch (softening point temperature 148 °C, volume distribution particle size Dv50 of 4.5 μm, coke value 40%) were mixed in a VC mixer for 30 min. Then, the mixed material was put into a reaction kettle. The reaction kettle adopted a method of gradually increasing the temperature, and the heating rate was 2 °C / min. While heating, the reaction kettle was maintained in an isothermal stirring state and heated to 190 °C. The reaction kettle was evacuated until the pressure reached -0.1 MPa. Then, it was kept warm for 2 h. After the heat preservation was completed, the reaction kettle was heated to 650 °C and kept warm for 2 h. Then, the reaction kettle was cooled down to about 160 °C. Then, petroleum pitch was gradually added into the reaction kettle. The mass ratio of the added amount of petroleum pitch this time to the previous petroleum pitch was 1:1. Then, the reaction kettle was heated to 190 °C again. The reaction kettle was evacuated until the pressure reached -0.1 MPa. Then, it was kept warm for 2 h. After the heat preservation was completed, the reaction kettle was heated to 650 °C and kept warm for 2 h. Then, it was cooled down by a method of condensation and cooling. Finally, the material treated in the above process was heat-treated at 1300 °C for 2 h. The sample after heat treatment was pulverized and sieved to obtain a carbon material without pores inside. Examples 2 to 7 and Comparative Example 7 [[ID=�]]

[0230] The manufacturing methods of the half-cell and the full-cell are similar to those of Example 1 except that the manufacturing process parameters of the carbon material are adjusted. Specifically, refer to Table 1.

[0231]

Table 1

[0232] The manufacturing methods of the half-cell and the full-cell are similar to those of Example 1 except that the parameters of the filler in the manufacturing process of the carbon material are adjusted. Specifically, refer to Table 2.

[0233]

Table 2

[0234] The manufacturing methods for half-cells and full-cells are similar to those of Example 3, except that the parameters in step 2 of the carbon material manufacturing process are adjusted; see Table 3 for details.

[0235] [Table 3] Examples 24-28

[0236] The manufacturing methods for half-cells and full-cells are similar to those in Example 1, except that the parameters in Step 1 of the carbon material manufacturing process are adjusted; see Table 4 for details.

[0237] [Table 4] Performance testing (1) Testing of the total pore area in the outer and inner regions of carbon material

[0238] The preparation binder is uniformly mixed with the carbon material powder, then applied to copper foil and dried at 60°C for 30 minutes. The sample is then cut into 6mm x 6mm pieces and attached to the sample stage of a CP-type argon ion cross-section polisher. The sample is then cut using a plasma beam to obtain a cross-section of the carbon material, ensuring that the cross-section passes through the center of the carbon material particles. The IB-09010 CP-type argon ion cross-section polisher from JEOL Japan Co., Ltd. can be used as the testing machine.

[0239] A scanning electron microscope was used to scan the cross-section of the carbon material. The test procedure can be described in JY / T010-1996. The test equipment may also be a Sigma 300 scanning electron microscope from ZEISS GmbH, Germany.

[0240] The region formed by extending 0.25 L from the surface of the carbon material particle into the particle interior is defined as the outer region, and the region inside the outer region is defined as the inner region, where L represents the short axis length of the carbon material particle. The total pore area S1 of the outer region and the total pore area S2 of the inner region of the carbon material were calculated using image processing software. The image processing software may also be AVIZO. (2) Testing of Raman spectra of carbon materials

[0241] Using a Raman spectrometer, the measurement conditions were as follows: excitation wavelength 532 nm, diffraction grating with 600 markings, objective lens magnification 50x, integration time 10 s, number of integrations 3, surface scanning, obtaining 100 D peak and G peak intensities, and 100 I peak intensities. D / I G Calculate the maximum and minimum 30 I D / I G Remove the remaining 40 points, and the average value of the carbon material I D / I G The test equipment may be a Horiba LabRAM HR800 Raman spectrometer. (3) Testing of the initial Coulomb efficiency of carbon materials

[0242] At 25°C, the prepared coin cell was first discharged with a constant current of 0.15mA to 0.005V, left to stand for 5 minutes, then discharged again with a constant current of 10μA to 0.005V, and the initial charge capacity of the coin cell was recorded. Subsequently, it was charged with a constant current of 0.3mA to 2.0V, and the initial charge capacity of the coin cell was recorded.

[0243] The initial Coulomb efficiency (%) of a carbon material = initial charge capacity of the coin cell / initial discharge capacity of the coin cell × 100%. (4) Testing of the cycle performance of secondary batteries

[0244] At 45°C, the manufactured secondary battery was charged with a constant current of 1C until it reached the upper cutoff voltage (corresponding to 100% SOC), then charged with a constant voltage until the current reached 0.05C, left to stand for 5 minutes, and then discharged at 1C until it reached the lower cutoff voltage (corresponding to 0% SOC). The discharge capacity at this time was recorded, which is the first discharge capacity. The secondary battery was subjected to a cycle charge-discharge test according to the above method, and the discharge capacity after one cycle was recorded. The capacity retention rate (%) of the secondary battery after 1000 cycles at 45°C = discharge capacity after 1000 cycles / first discharge capacity × 100%. (5) Testing of the storage performance of secondary batteries

[0245] At 25°C, the rechargeable battery manufactured as described above was charged with a constant current of 1C until it reached the upper cutoff voltage (corresponding to 100% SOC). Then, it was charged with a constant voltage until the current reached 0.05C, and after standing for 5 minutes, the rechargeable battery was discharged with a constant current of 1C until it reached the lower cutoff voltage (corresponding to 0% SOC). The discharge capacity at this time was recorded, which was then used as the discharge capacity before storage.

[0246] At 25°C, the manufactured secondary battery was charged with a constant current of 1C up to the upper cutoff voltage (corresponding to 100% SOC), and then charged with a constant voltage until the current dropped to 0.05C. After that, it was stored in a constant temperature bath at 60°C for 150 days. The capacity retention rate (%) of the secondary battery after 150 days of storage at 60°C = discharge capacity after storage / discharge capacity before storage × 100%.

[0247] [Table 5] JPEG0007849514000006.jpg212170

[0248] The specific surface area, volume distribution particle size, powder resistivity, powder compressibility density, tap density, and degree of graphitization of the carbon materials produced in Examples 1 to 28 were all within the ranges described in the specification of this application.

[0249] The Raman spectra of the carbon materials produced in the embodiments of this application are all 0.150 ≤ I D / I GThe condition ≤0.280 is satisfied, and in this case, on the one hand, the content of irregular carbon can be effectively reduced, the surface activity of the carbon material can be lowered, and the consumption of active ions due to the formation of SEI films on the particle surface can be reduced, and on the other hand, the carbon material can be given a stable structure and particle fragmentation can be avoided as much as possible. Therefore, the carbon material according to the present invention has small volume expansion, high structural stability, and low surface activity, and the battery can be made to have a high gram capacity, high initial Coulomb efficiency, high capacity retention rate after cycles, and high capacity retention rate after storage.

[0250] The Raman spectra of the carbon materials produced in Comparative Examples 1-7 were all 0.150 ≤ I. D / I G The value of ≤0.280 is not satisfied, and none of the batteries can be made to have high gram capacity, high initial Coulomb efficiency, high capacity retention rate after cycles, and high capacity retention rate after storage. The carbon material I produced in Comparative Examples 1, 3-4 and 6 D / I G In all cases, the I of the carbon material is greater than 0.280. In this case, the irregular carbon content in the carbon material is high, there are many surface active sites in the carbon material, and the surface defect content is high, resulting in a large irreversible consumption of active ions. Furthermore, it is not possible to achieve a battery with high gram capacity, high initial Coulomb efficiency, high capacity retention rate after cycles, and high capacity retention rate after storage. The I of the carbon material produced in Comparative Examples 2, 5 and 7 D / I G In all cases, the values ​​are less than 0.150. In this case, the content of irregular carbon on the surface of the carbon material particles is low, and there are fewer surface active sites on the particles. However, the ability to rapidly desorb and insert active ions is poor, and the volume change of the carbon material during the battery charge and discharge process is large, making the carbon material particles more prone to fragmentation. Furthermore, it is not possible to achieve a battery with high gram capacity, high initial Coulomb efficiency, high capacity retention rate after cycles, and high capacity retention rate after storage.

[0251] In summary, the test results in Table 5 show that if the carbon material further satisfies S2 > S1, selectively satisfies 1.5 ≤ S2 / S1 ≤ 450, and more selectively satisfies 2 ≤ S2 / S1 ≤ 400, then the carbon material can further improve the gram capacity, initial Coulomb efficiency, capacity retention rate after cycling, and capacity retention rate after storage of the battery. In this case, the carbon material particles further have the characteristic of having a large number of pores and / or large pore size in the internal region, but a small number of pores and / or small pore size in the external region. The pore structure in the internal region of the carbon material can secure the expansion space necessary for volume changes of the carbon material particles, thereby reducing the risk of new interfaces being generated due to the crushing of carbon material particles, and consequently reducing the occurrence of side reactions and irreversible capacity loss of the secondary battery. Because the carbon material has fewer pores in its external region and / or smaller pore size, the carbon material particles have a more stable structure, and the penetration of the electrolyte into the internal pore structure of the carbon material particles can be avoided as much as possible. This reduces the occurrence of side reactions and the consumption of active ions due to the formation of SEI films inside the particles. As a result, the gram capacity of the battery, the initial Coulomb efficiency, the capacity retention rate after cycling, and the capacity retention rate after storage can be further improved.

[0252] None of the carbon materials produced in Comparative Examples 1-6 satisfy the S2 > S1 condition.

[0253] Comparative Example 1 uses untreated natural spheroidal graphite as the carbon material, and both its interior and exterior have many pores.

[0254] The carbon materials produced in Comparative Examples 2-4 were formed by creating a carbon layer coating on the surface of natural spheroidal graphite. However, this carbon layer was only present on the surface of the natural spheroidal graphite, failing to achieve a filling effect. Furthermore, the carbon layer did not effectively prevent the electrolyte from penetrating the pore structure inside the particles. Moreover, its effect on improving the initial Coulomb efficiency, cycle performance, and storage performance of the battery was limited.

[0255] In Comparative Example 5, when manufacturing the carbon material, the softening point temperature of the filler used is low, and small molecular substances in the filler volatilize during the graphitization treatment. As a result, the carbon that actually remains in the filling area cannot effectively fill the pore structure of the natural spheroidal graphite, thus failing to achieve an effective filling effect. Furthermore, it is not possible to effectively prevent the electrolyte from penetrating the pore structure inside the particles, and the improvement effect on the battery's cycle performance and storage performance is limited.

[0256] In Comparative Example 6, when manufacturing the carbon material, the filler material was filled into all the pore structures inside the natural spheroidal graphite particles by vacuum evacuation, and as a result, there were no pore structures inside the carbon material particles obtained at this time. Consequently, the volume change that occurs during the desorption and insertion process of active ions in the carbon material is large, the particles are more easily crushed, and the improvement effect on the battery's cycle performance and storage performance is limited.

[0257] Furthermore, this application is not limited to the embodiments described above. The embodiments described above are illustrative examples, and any configuration that is substantially identical to the technical idea and produces similar effects within the scope of the technical proposal of this application is included within the technical scope of this application. In addition, any modifications to the embodiments that a person skilled in the art could conceive, or other forms constructed by combining some of the components of the embodiments, are also included within the scope of this application, as long as they do not depart from the spirit of this application.

Claims

1. A carbon material, It has a porous structure, and 0.150 ≤ I Ｄ / I Ｇ Satisfying ≤ 0.280, I Ｄ This is the Raman spectrum of the carbon material at 1350 ± 50 cm⁻¹. －１ This represents the D peak intensity at I Ｇ This is the Raman spectrum of the carbon material at 1580 ± 50 cm⁻¹. －１ This represents the G-peak intensity at, The carbon material comprises an outer region and an inner region located inside the outer region, wherein the outer region is a region formed by extending a distance of 0.25 L from the particle surface of the carbon material into the particle interior, where L is the short axis length of the carbon material particle, and when the total pore area of ​​the outer region is S1 and the total pore area of ​​the inner region is S2, then S2 > S1. Carbon materials.

2. 0.152 ≤ I Ｄ / I Ｇ ≤ 0.280 The carbon material according to claim 1.

3. The carbon material includes one or more pore structures with a pore area of 0.15 μm ２ or more, The carbon material according to claim 1.

4. 1.5 ≤ S ２ / S １ ≤ 450 The carbon material according to claim 1.

5. 0.01 μm ２ ≤S １ ≤ 5.0 μm ２ and / or, 2.5 μm ２ ≤S ２ ≤25.0 μm ２ That is, The carbon material according to claim 1.

6. L ≥ 4 μm. The carbon material according to claim 1.

7. The area of ​​the pore structure in the external region of the carbon material is 0.15 μm². ２ The following and / or, The internal region of the carbon material has an area of ​​0.15 μm². ２ Includes one or more pore structures that are as described above, The carbon material according to claim 1.

8. The interlayer distance in the outer region of the carbon material is d １ Let d be the interlayer distance in the internal region of the carbon material. ２ In this case, the carbon material is d １ ≥ d ２ Satisfying the conditions, d １ The wavelength range is 0.33565 nm to 0.33620 nm. d ２ The range is 0.33557 nm to 0.33589 nm. The carbon material according to claim 1.

9. The carbon material satisfies at least one of the following conditions: (1) The specific surface area of ​​the carbon material is 2.1 m². ２ / g or less, (2) The volume distribution particle size Dv50 of the carbon material is 6.0 μm to 30.0 μm. (3) The volume distribution particle size Dv90 of the carbon material is 16.0 μm to 45.0 μm. (4) The particle size distribution (Dv90 - Dv10) / Dv50 of the carbon material is 1.55 or less. The carbon material according to claim 1.

10. The carbon material satisfies at least one of the following conditions: (1) The powder resistivity of the carbon material at a pressure of 8 MPa is 0.006 Ω·cm to 0.051 Ω·cm. (2) The powder compression density of the carbon material under a pressure of 20,000 N is 1.70 g / cm³. ３ ~1.95 g / cm ３ And, (3) The tap density of the carbon material is 0.80 g / cm³ ３ ~1.35 g / cm ３ And, (4) The gram capacity of the carbon material is 350 mAh / g to 372 mAh / g, (5) The degree of graphitization of the carbon material is 92.0% to 98.0%. (6) The topography of the carbon material includes one or more of the following: bulky, spherical, and subspherical. The carbon material according to claim 1.

11. A method for manufacturing carbon materials, Step 1 provides a raw material having multiple pore structures, After uniformly mixing the raw materials and filler in a predetermined ratio, the first temperature T １ Then the first time t １ Step 2 involves maintaining the temperature to obtain the intermediate, The obtained intermediate is heated to a second temperature T ２ Then the second time t ２ The process includes step 3, which involves maintaining the temperature to obtain a carbon material, The carbon material includes a porous structure, and the carbon material has a density of 0.150 ≤ I Ｄ / I Ｇ Satisfying ≤ 0.280, I Ｄ This is the Raman spectrum of the carbon material at 1350 ± 50 cm⁻¹. －１ This represents the D peak intensity at I Ｇ This is the Raman spectrum of the carbon material at 1580 ± 50 cm⁻¹. －１ This represents the G-peak intensity at, The carbon material comprises an outer region and an inner region located inside the outer region, wherein the outer region is a region formed by extending a distance of 0.25 L from the particle surface of the carbon material into the particle interior, where L is the short axis length of the carbon material particle, and when the total pore area of ​​the outer region is S1 and the total pore area of ​​the inner region is S2, then S2 > S1. A method for manufacturing carbon materials.

12. The aforementioned raw materials satisfy at least one of the following conditions: (1) The raw material contains natural graphite, and the natural graphite contains one or more types of flake graphite, natural spheroidal graphite, and microcrystalline graphite. (2) The volume distribution particle size Dv50 of the raw material is 6.0 μm to 30.0 μm. (3) The specific surface area of ​​the raw material is 2.5 m². ２ It is 1 / g or more. The method according to claim 11.

13. The filler satisfies at least one of the following conditions: (1) The softening point temperature of the filler is 100°C to 180°C. (2) The coke content of the filler is 25% to 50%, (3) The volume distribution particle size Dv50 of the filler is 6 μm or less. The method according to claim 11.

14. The filler includes one or more of the following: coal pitch, petroleum pitch, polymer compounds, and resins. The method according to claim 13.

15. The mass ratio of the filler to the raw material is (10-32):

100. The method according to claim 11.

16. After uniformly mixing the raw materials and the filler in a predetermined ratio, the first temperature T １ The heating process to raise the temperature to a certain level is a stepwise heating process, and includes a first heating process, a second heating process, and a third heating process. The method according to claim 11.

17. The first heating step involves raising the temperature to 200°C to 250°C, maintaining the temperature at that temperature for 1 to 2 hours, and / or The second heating step involves raising the temperature to 450°C to 550°C, maintaining the temperature at that temperature for 1 to 2 hours, and / or The third heating step involves the first temperature T １ The temperature is raised to a certain level, and the temperature is maintained at that level for a first time t. １ Keep warm The method according to claim 16.

18. The first temperature T is increased at a rate of 1°C / min to 10°C / min. １ Heat up to this point. The method according to claim 11.

19. The first temperature T １ The temperature range is 700°C to 1200°C, and / or The first time t １ It is 1 to 5 hours. The method according to claim 11.

20. The second temperature T ２ The temperature range is 1800°C to 2600°C, and / or The second time t ２ It is 1.5 to 6 hours. The method according to claim 11.

21. Equipped with a negative electrode sheet, The negative electrode sheet comprises the carbon material described in any one of claims 1 to 10. Secondary battery.

22. A secondary battery as described in claim 21, Power consumption equipment.

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