Carbon material, method for producing the same, secondary battery and power consumption device 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 belongs to the technical field of batteries, and specifically relates to a carbon material, a method for manufacturing the same, a secondary battery including the same, and a power consumption device.

Background Art

[0002] In recent years, secondary batteries have been widely used in many fields such as energy storage power systems such as hydropower, thermal power, wind power, and solar power plants, and electric tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. As the application range of secondary batteries becomes increasingly wide, profound challenges are required for the performance of secondary batteries. For example, secondary batteries are required to have various performances such as energy density and service life. The negative electrode active material is an important component of the secondary battery and affects the performance of the secondary battery. Currently, the negative electrode active material mainly includes graphite, but the problems faced in the prior art are that it is difficult to make high-capacity graphite have a high initial Coulomb efficiency, and it is also difficult to make the secondary battery have good cycle performance and storage performance.

Summary of the Invention

[0003] An object of this application is to provide a carbon material, a method for manufacturing the same, a secondary battery including the same, and a power consumption device that can make the secondary battery have a high initial Coulomb efficiency, a high energy density, good cycle performance, and storage performance.

[0004] The first aspect of this application provides a carbon material, the carbon material includes a pore structure, and satisfies 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.

[0005] The carbon material according to the present application can effectively reduce the irreversible capacity loss of a secondary battery, improve the capacity exhibition characteristics 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 preferably 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 minor 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 optionally, 2 ≦ S2 / S1 ≦ 400.

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

[0011] In any embodiment of the present application, 0.01 μm 2 ≦ S1 ≦ 5.0 μm 2 and optionally, 0.02 μm 2 ≦ S1 ≦ 4.5 μm 2 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, reducing the occurrence of side reactions and reducing the consumption of active ions due to the formation of the SEI film inside the carbon material particles, while not affecting the transport performance of active ions and electrons.

[0012] In any embodiment of the present application, 2.5 μm 2 ≦ S2 ≦ 25.0 μm 2 and optionally, 3.0 μm 2 ≦ S2 ≦ 22.5 μm 2 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 ensured for the volume change of the carbon material particles, reducing the risk of generating new interfaces due to the crushing of the 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 the SEI film 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 optionally, 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 μm 2 or less, and optionally 0.10 μm2 The following is true. When the area of the pore structure in the external region of the carbon material is controlled within the above range, a dense structure can be given to the external region of the carbon material, thereby effectively improving the structural stability of the carbon material, avoiding as much as possible the penetration of the electrolyte into the pore structure inside the carbon material particles, and ultimately effectively improving the cycle performance and storage performance of the secondary battery.

[0015] In any embodiment of the present application, in the internal region of the carbon material, there is one or more pore structures with an area of 0.15 μm 2 or more, and optionally, one or more pore structures with an area of 0.15 μm 2 to 2.0 μm 2 are included. When the internal region of the carbon material contains pore structures of the above area, a sufficient and stable expansion space can be ensured for the volume change of the carbon material particles, reducing the risk of crushing of the carbon material particles, while improving the compression density of the carbon material.

[0016] In any embodiment of the present application, if the interlayer distance of the external region of the carbon material is denoted as d1 and the interlayer distance of the internal region of the carbon material is denoted as d2, the carbon material satisfies d1 ≧ d2, and optionally, d1 > d2. Since the interlayer distance of the external region of the carbon material is large, which is advantageous for the rapid insertion and desorption of active ions, the dynamic performance of the secondary battery can be further improved. Since the interlayer distance of the internal region of the carbon material is small, which is advantageous for the increase in the gram capacity (capacity per gram) and compression density of the carbon material, the energy density of the secondary battery can be further increased.

[0017] In any embodiment of the present application, d1 is 0.33565 nm to 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 m 2 / g or less, and optionally 0.7 m2 / g ~ 1.8 m 2 / g. Since the carbon material of the present application has a low specific surface area and low surface activity, it can reduce the consumption of active ions due to the formation of the SEI film, improve the initial Coulomb efficiency of the carbon material, and further improve the cycle performance and storage performance of the secondary battery.

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

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

[0022] When the volume distribution particle size Dv50 and / or Dv90 of the carbon material is within the above range, it is beneficial to improve the transport performance of active ions and electrons, so 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 optionally 0.5 to 1.50. Thereby, it is beneficial to improve the compression density of the carbon material, so the energy density of the secondary battery can be further improved.

[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 optionally 0.010 Ω·cm to 0.040 Ω·cm. When the powder resistivity of the carbon material is within the above range, it is beneficial to improve the transport performance of electrons, so the cycle performance and dynamic performance of the secondary battery can be further improved.

[0025] In any embodiment of the present application, the powder compression density of the carbon material under a pressure of 20000 N is 1.70 g / cm 3 ~ 1.95 g / cm 3and optionally 1.72 g / cm 3 ~1.92 g / cm 3 When the powder compression density of the carbon material is within the above range, the compression density of the negative electrode sheet can be increased, the energy density of the secondary battery can be further increased, and it is advantageous for improving the transport performance of active ions and electrons, so that the cycle performance and dynamic performance of the secondary battery are improved.

[0026] In any embodiment of the present application, the tap density of the carbon material is 0.80 g / cm 3 ~1.35 g / cm 3 and optionally 0.85 g / cm 3 ~1.30 g / cm 3 When the tap density of the carbon material is within the above range, the compression density of the negative electrode sheet can be increased, the energy density of the secondary battery can be further increased, and it is advantageous for improving the transport performance of active ions and electrons, so that the cycle performance and dynamic performance of the secondary battery are improved.

[0027] In any embodiment of the present application, the gram capacity of the carbon material is 350 mAh / g to 372 mAh / g, and optionally 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 graphitization degree of the carbon material is 92.0% to 98.0%, and optionally 92.5% to 97.6%. When the graphitization degree of the carbon material is within the above range, it is advantageous for the secondary battery to have 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 massive, spherical and quasi-spherical shapes.

[0030] A second aspect of the present application is a method for manufacturing a carbon material, including step 1 of providing a raw material having a plurality of pore structures; step 2 of uniformly mixing the raw material and a filler at a predetermined ratio and then holding the mixture at a first temperature T1 for a first time t1 to obtain an intermediate; and step 3 of holding the obtained intermediate at a second temperature T2 for a second time t2 to obtain a carbon material, wherein the carbon material includes a pore structure, and 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. A method for manufacturing a carbon material is provided.

[0031] In any embodiment of the present application, the raw material includes natural graphite, and optionally, the natural graphite includes one or more of flake graphite, natural spherical 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 optionally 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 m 2 / g or more, and optionally 2.5 m 2 / g to 10.0 m 2 / g.

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

[0035] In any embodiment of the present application, the coke value of the filler is 25% to 50%, and optionally 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 optionally 1 μm to 5 μm.

[0037] In any embodiment of the present application, the filler contains one or more of coal pitch, petroleum pitch, polymer compounds, and resins, and optionally contains 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 to 32):100, and optionally (15 to 25):100.

[0039] When parameters such as the type of filler, softening point, coke value, and addition amount are adjusted within the above ranges, after the filler melts due to heat, its viscosity is not high, it maintains good fluidity, raw material particles are not easily adhered, and the aggregation of raw material particles in the subsequent manufacturing process can be reduced. Thereby, problems such as an increase in surface defects of carbon material particles and an increase in surface active sites due to the depolymerization process can be reduced.

[0040] In any embodiment of the present application, the temperature-raising process of raising the temperature of the raw material and the filler to a first temperature T1 after uniformly mixing them at a predetermined ratio is a stepwise temperature-raising process, and optionally includes a first temperature-raising process, a second temperature-raising process, and a third temperature-raising process.

[0041] In any embodiment of the present application, in the first temperature-raising process, the temperature is raised to 200°C to 250°C and held at this temperature for 1 h to 2 h.

[0042] In any embodiment of the present application, in the second temperature-raising process, the temperature is raised to 450°C to 550°C and held at this temperature for 1 h to 2 h.

[0043] In any embodiment of the present application, in the third temperature-raising process, the temperature is raised to the first temperature T1 and held at this temperature for a first time t1.

[0044] In any embodiment of the present application, 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 optionally 720 °C to 1100 °C.

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

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

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

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

[0050] Adjusting one or more of the second temperature and the second time within the above ranges is advantageous for adjusting the content of irregular carbon in the carbon material within an appropriate range, and for making I D / I G within an appropriate range, and also for satisfying that S2 / S1 of the carbon material is within an appropriate range.

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

[0052] The fourth aspect of the present application provides a power consumption device including the secondary battery of the third aspect of the present application.

[0053] The carbon material according to the present application can effectively reduce the irreversible capacity loss of the 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. Since the power consumption device of the present application is equipped with the secondary battery of the present application, it has at least the same advantages as the secondary battery.

Brief Description of the Drawings

[0054] To more clearly explain the technical solutions of the embodiments of the present application, the drawings that need to be used in the embodiments of the present application are briefly described below. Obviously, the drawings described below are only some embodiments of the present application. Even without creative labor, those skilled in the art can obtain other drawings based on these drawings.

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Description of Reference Signs

[0055] In the drawings, they are not necessarily drawn to actual scale. The descriptions of the drawing symbols are as follows. 1: Battery pack, 2: Upper housing, 3: Lower housing, 4: Battery module, 5: Secondary battery, 51: Case, 52: Electrode assembly, 53: Cover plate, 100: Carbon material, 101: Outer region, 102: Inner region.

Embodiments for Carrying Out the Invention

[0056] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the carbon material of the present application, a method for manufacturing the same, and a secondary battery and a power consumption device using the same will be described in detail. However, there may be cases where more detailed explanations than necessary are omitted. For example, detailed explanations of known matters or duplicate explanations of actually the same structure may be omitted. This is to avoid making the following explanations unnecessarily redundant and to facilitate the understanding of those skilled in the art. Furthermore, the drawings and the following explanations are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter described in the claims.

[0057] The "range" disclosed in this application is limited in the form of a lower limit and an upper limit. A predetermined range is defined by selecting one lower limit and one upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The range thus defined may be a range including or excluding the end values, and may be arbitrarily combined, that is, any lower limit may be combined with any upper limit to form a range. For example, if ranges of 60 to 120 and 80 to 110 are cited for a specific parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Also, when the minimum range values 1 and 2 and the maximum range values 3, 4, and 5 are cited, ranges of 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 may all be contemplated. In this application, unless otherwise explained, the numerical range "a to b" is a shorthand notation 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 in this specification that all real numbers between "0 to 5" are cited, and "0 to 5" is a shorthand notation for combinations of these numerical values. Also, a notation that a certain parameter is an integer of 2 or more (≧2) is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0058] Unless otherwise specified, all embodiments and selectable embodiments of this application may be combined with each other to form a new technical solution. Also, such a technical solution is considered to be included in the disclosure content of this application.

[0059] Unless otherwise specified, all technical features and selectable technical features of this application may be combined with each other to form a new technical solution. Also, such a technical solution is considered to be included in the disclosure content of this application.

[0060] Unless otherwise specified, all steps of this application may be performed in sequence or randomly, but it is preferred to be performed in sequence. For example, the fact that the above method includes steps (a) and (b) means that the above method may include steps (a) and (b) performed in sequence, or may include steps (b) and (a) performed in sequence. For example, when it is mentioned that the above method may further include step (c), it means that step (c) may be added to the above method in any order. For example, the above method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), etc.

[0061] Unless otherwise specified, "comprising" and "including" described in this application are meant to be open-ended, and may also be closed-ended. For example, the above "comprising" and the above "including" can represent further "comprising" or "including" other components not listed, or "comprising" or "including" only the components listed.

[0062] Unless otherwise specified, in this application, the term "or" is inclusive. For example, the phrase "A or B" represents "A, B, or both A and B". More specifically, any of the following 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 described in this application have the meanings known to those skilled in the art.

[0064] Unless otherwise specified, the numerical values of each parameter mentioned in this application can be measured by various test methods commonly used in this field. For example, they can be measured according to the test methods provided in this application.

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

[0066] In the present application, the terms "a plurality" and "a plurality of types" refer to two or more.

[0067] Graphite is classified into artificial graphite and natural graphite depending on the manufacturing process and the source. When manufacturing artificial graphite, it is generally necessary to go through a high-temperature graphitization treatment process. Since the energy consumption of this process is high and the cost is high, the cost of artificial graphite is high. Since natural graphite is derived from nature, it has the advantage of being relatively inexpensive. In addition, natural graphite also has the advantage of high capacity.

[0068] Natural graphite mainly includes flake graphite, natural spherical graphite, and microcrystalline graphite. Usually, different from artificial graphite, natural graphite has a very large number of pores and defects inside and outside the particles. In the initial charging process of a secondary battery, the electrolyte reacts with the particle surface and the pores inside the particles to cause many side reactions, resulting in a high initial irreversible capacity loss of the secondary battery, a low initial Coulomb efficiency, and poor cycle performance and storage performance. In particular, flake graphite and natural spherical graphite have a high crystallinity and a high degree of graphitization, and the microstructure is often a layered structure. Due to such a structure, the volume change occurring in the process of desorption and insertion of active ions in natural graphite becomes large, so it is easy to cause the crushing of the graphite layered structure and the crushing of the particles. After the particles are crushed, the exposed fresh surface continues to react with the electrolyte, so the irreversible capacity loss of the secondary battery further increases.

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

[0070] The coating treatment on the particle surface mainly involves uniformly mixing natural graphite and a coating agent (such as pitch, polymer compound, etc.), and then performing heat treatment to coat a layer of amorphous carbon on the surface of natural graphite particles to slightly repair the defects on the particle surface. However, during the research process, the inventors of the present application found that the amorphous carbon layer coated on the surface causes a decrease in the gram capacity and / or compression density of natural graphite, which affects the energy density of the secondary battery. At the same time, there are still many defects on the particle surface of the amorphous carbon layer coated on the surface, and the amorphous carbon layer coated on the surface cannot effectively prevent the electrolyte from infiltrating into 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 filling treatment inside the particles mainly involves mixing natural graphite and a filler (such as pitch, polymer compound, etc.), and filling the filler into the pores inside the particles by means of a predetermined pressure, vacuum pumping, temperature increase, etc. to obtain natural graphite without pores inside the particles. However, during the research process, the inventors of the present application found that due to a large amount of carbon filled inside the particles, especially soft carbon, both the gram capacity and compression density of natural graphite decrease, which affects the energy density of the secondary battery. At the same time, since all the pores inside the natural graphite particles are filled with carbon, the volume change during the process of desorption and insertion of active ions in natural graphite becomes larger, and the particles are more likely to be crushed. Furthermore, the destruction and reconstruction of the SEI film on the particle surface are repeated, 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 the prior art, since the surface of the natural graphite without pores inside the particles is continuously coated with an amorphous carbon layer, the gram capacity and / or compression density of natural graphite further decrease, and at this time, since there are still many surface defects on the particles, the service life of the secondary battery cannot be effectively improved.

[0072] Therefore, after modifying natural graphite by the coating treatment on the surface of the particles and / or the filling treatment inside the particles, the irreversible capacity loss of the secondary battery can be reduced to a certain extent, and the initial Coulomb efficiency of the secondary battery can be improved. However, the improvement effect on the initial Coulomb efficiency of the secondary battery is limited, the energy density of the secondary battery is also lost, and the capacity performance of the secondary battery during long-term cycling and storage is still poor.

[0073] In view of this, through a large amount of research, the inventors of the present application have provided a new carbon material that has a high gram capacity, a high initial Coulomb efficiency, and a small volume change, and can endow the secondary battery with a high initial Coulomb efficiency, a high energy density, and good cycle performance and storage performance. Carbon material

[0074] The first aspect of the embodiment of the present application includes a pore structure, and 0.150 ≦ I D / I G ≦ 0.280 is satisfied, 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.

[0075] The carbon material according to the present application can effectively reduce the irreversible capacity loss of the secondary battery, improve the capacity performance of the secondary battery, and endow the secondary battery with a high initial Coulomb efficiency, a high energy density, and good cycle performance and storage performance. The reasons are at least as follows.

[0076] The carbon material provided in this application contains a pore structure. In this application, when it is stated that the carbon material "contains a pore structure", it 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 a magnification of 1000 times), that is, the pore structure in the raw material for manufacturing the carbon material is not completely filled. Thereby, the pore structure in the carbon material can ensure the expansion space required for the volume change of the carbon material particles, thereby reducing the risk of generation of new interfaces due to crushing of the carbon material particles, and consequently 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.

[0077] The carbon material provided in this application satisfies 0.150 ≦ I D / I G ≦ 0.280. I D / I G can reflect the irregularity of the carbon material surface layer. The smaller I D / I G is, the lower the content of irregular carbon on the particle surface of the carbon material, the fewer the active sites on the particle surface, and the less the irreversible consumption of active ions. However, the inventors of this application found in the process of research that it is not the case that the lower the content of irregular carbon, the better. If the content is too low, both the crystallinity and graphitization degree of the carbon material will increase. In this case, it is disadvantageous for the rapid desorption and insertion of active ions. At the same time, during the charge and discharge process of the secondary battery, the volume change of the carbon material is large, which increases the risk of crushing of the carbon material particles, and furthermore, repeated destruction and reconstruction of the SEI film on the particle surface are 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. The inventors found in further research that when the carbon material satisfies 0.150 ≦ I D / I G ≦ 0.280, it can effectively reduce the content of irregular carbon, lower the surface activity of the carbon material, reduce the consumption of active ions due to the formation of the SEI film on the particle surface, while giving the carbon material a stable structure and avoiding crushing of the particles as much as possible.

[0078] Therefore, when the carbon material includes a pore structure and satisfies 0.150 ≦ I D / I G ≦ 0.280, the volume expansion of the carbon material is small, the structural stability is high, and the surface activity is low. Therefore, it can have a high gram capacity, a high initial Coulomb efficiency, and a small volume change, and can endow the secondary battery with a high initial Coulomb efficiency, a high energy density, and good cycle performance and storage performance.

[0079] Figure 1 is the Raman spectrum of an embodiment of the carbon material of the present application. 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. In the present application, I D / I G can be represented by the ratio of the D peak height to the G peak height of the Raman spectrum.

[0080] In some embodiments, I D / I G can be in the 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 value thereof. Optionally, 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 ≦ 0.180. The inventors have further studied that 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, 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.

[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 extending 0.25L from the particle surface of the carbon material to the particle interior, where L refers to the minor axis length of the carbon material particles. Denote the total pore area of the outer region as S1 and the total pore area of the inner region 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 inner 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. Since the number of pores in the outer region of the carbon material is small and / or the pore size is small, the carbon material particles can be provided with 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. 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 / S1 ≤ 150, 2.5 ≤ S2 / S1 ≤ 100, 2.5 ≤ S2 / S1 ≤ 50. The inventors have found through further studies 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 0.05 μm ≤ S1 ≤ 2 μm 2 When the total pore area of the outer region of the carbon material is within the above range, a stable structure can be given to the carbon material particles, and the penetration of the electrolyte into the pore structure inside the carbon material particles can be avoided as much as possible. Thereby, the occurrence of side reactions is reduced, and while reducing the consumption of active ions due to the formation of the SEI film inside the carbon material particles, it does not affect the transport performance of active ions and electrons.

[0086] In some embodiments, 2.5 μm 2 2.5 μm ≤ S2 ≤ 25.0 μm 2 and optionally, 3.0 μm 2 3.0 μm ≤ S2 ≤ 22.5 μm 2 and 3.0 μm 2 3.0 μm ≤ S2 ≤ 20 μm 2 and 3.0 μm 2 3.0 μm ≤ S2 ≤ 18 μm and 3.0 μm 2 3.0 μm ≤ S2 ≤ 16 μm 2 and 3.0 μm 2 3.0 μm ≤ S2 ≤ 14 μm 2 and 3.0 μm 2 3.0 μm ≤ S2 ≤ 12 μm 2 and 3.0 μm 2 3.0 μm ≤ S2 ≤ 10 μm 2 and 3.0 μm 2 3.0 μm ≤ S2 ≤ 8 μm 2 When the total pore area of the inner region of the carbon material is within the above range, a sufficient and stable expansion space can be ensured for the volume change of the carbon material particles, the risk of generating a new interface due to the crushing of the carbon material particles is reduced, the occurrence of side reactions on the surface of the new interface is reduced, and while reducing the consumption of active ions due to the formation of the SEI film on the surface of the new interface, the capacity of the carbon material can be increased and the initial Coulomb efficiency can be improved.

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

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

[0089] In the present application, the short axis length of the particle refers to the minimum value when the connecting line of two points on the surface of the particle passes through the geometric center of the particle.

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

[0091] The cross-section of the carbon material can be manufactured by using a cross-section polisher (for example, IB-09010 CP type argon ion cross-section polisher of JEOL Ltd., Japan). Then, referring to JY / T010-1996, the cross-section of the carbon material is scanned by using a scanning electron microscope (for example, Sigma 300 type scanning electron microscope of 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 by using image processing software (for example, AVIZO).

[0092] In some embodiments, the short axis length L of the carbon material particles satisfies L≧4 μm, and optionally, 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, 8 μm≦L≦16 μm.

[0093] In some embodiments, the area of the pore structure in the outer region of the carbon material is 0.15 μm or less, and optionally 0.10 μm or less. The inventors have further studied that controlling the area of the pore structure in the outer region of the carbon material within the above range can endow the outer region of the carbon material with a dense structure, thereby effectively improving the structural stability of the carbon material, avoiding as much as possible the penetration of the electrolyte into the pore structure inside the carbon material particles, and ultimately effectively improving the cycle performance and storage performance of the secondary battery. Of course, this application does not limit that the area of all pore structures in the outer region of the carbon material is 2 less than or equal to, for example, it can be controlled to be 95% or more, and optionally, the area of 99% or more of the pore structures is 2 less than or equal to, and optionally 0.10 μm 2 less than or equal to.

[0094] In some embodiments, the inner region of the carbon material includes one or more pore structures with an area of 0.15 μm 2 or more, and optionally, one or more pore structures with an area of 0.15 μm 2 to 2.0 μm 2 are included. The inventors have further studied that including pore structures with the above area in the inner region of the carbon material can ensure a sufficient and stable expansion space for the volume change of the carbon material particles, reduce the risk of crushing of the carbon material particles, while increasing the compression density of the carbon material.

[0095] In some embodiments, the interlayer distance of the outer region of the carbon material is d1, the interlayer distance of the inner region of the carbon material is d2, and the carbon material satisfies d1 ≧ d2, and optionally, d1 > d2.

[0096] Since the interlayer distance of the external region of the carbon material is large, which is advantageous for the rapid insertion and desorption of active ions, the dynamic performance of the secondary battery can be further improved. Since the interlayer distance of the internal region of the carbon material is small, which is advantageous for the increase in the gram capacity and compression density of the carbon material, the energy density of the secondary battery can be further increased.

[0097] In some embodiments, d1 is 0.33565 nm to 0.33620 nm.

[0098] In some embodiments, d2 is 0.33557 nm to 0.33589 nm.

[0099] The interlayer distances of different regions of the carbon material can be measured by known devices and methods in this field. For example, it can be measured using a High Resolution Transmission Electron Microscope (HRTEM). The test equipment can use the scanning transmission electron microscope of Spectra S / TEM from Thermo Fisher Scientific.

[0100] In some embodiments, the topography of the carbon material includes one or more of massive, spherical, and quasi-spherical shapes. This is advantageous for increasing the compression density of the negative electrode sheet and thus increasing the energy density of the secondary battery.

[0101] In some embodiments, the carbon material includes primary particles. Optionally, the quantitative ratio of the primary particles in the carbon material is 50% or more, for example, 55% - 95%, 60% - 100%, 65% - 90%, 65% - 80%, 70% - 100%, 75% - 90%, 80% - 100%, 90% - 100%, or 95% - 100%. When the carbon material contains an appropriate ratio of primary particles, the carbon material can have high structural stability, can also reduce the occurrence of side reactions, and can increase the compression density of the negative electrode sheet, so the energy density of the secondary battery can also be increased.

[0102] In some embodiments, the carbon materials may all be primary particles, that is, the quantitative ratio of the primary particles in the carbon materials is 100%.

[0103] Both the primary particles and the secondary particles have meanings known in the art. The primary particles refer to non-aggregated particles. The secondary particles refer to aggregated particles in which two or more primary particles are aggregated. The primary particles and the secondary particles can be distinguished using a scanning electron microscope (SEM) image.

[0104] In the present application, the quantitative ratio of the primary particles in the carbon material can be measured by the following method. Select any one test sample from the negative electrode film layer, select any plurality of test regions in the test sample, acquire images of the plurality of test regions using a scanning electron microscope, and count the ratio of the number of carbon material particles with primary particle topography to the total number of carbon material particles in each image. The average value of the plurality of statistical results is the quantitative ratio of the primary particles in the carbon material.

[0105] In some embodiments, the graphitization degree of the carbon material is 92.0% to 98.0%, and optionally 92.5% to 97.6%. When the graphitization degree of the carbon material is within the above range, it is advantageous for the secondary battery to have high energy density, good cycle performance, storage performance, and dynamic performance.

[0106] The graphitization degree of the carbon material has a meaning known in the art and can be measured by devices and methods known in the art. For example, it can be measured using an X-ray diffractometer (e.g., Bruker D8 Discover). The measurement is based on JIS K 0131-1996 and JB / T 4220-2011 to obtain the average interlayer distance d of the (002) crystal plane in the crystal structure of the carbon material 002 and then the graphitization degree can be calculated based on the formula g = (0.344 - d 002 ) / (0.344 - 0.3354) × 100%. In the above formula, d 002It is the average interlayer distance of the (002) crystal plane in the crystal structure of the carbon material represented in nanometers (nm).

[0107] In some embodiments, the specific surface area of the carbon material is 2.1 m 2 / g or less, optionally 0.7 m 2 / g to 1.8 m 2 / g, 0.7 m 2 / g to 1.7 m 2 / g, 0.7 m 2 / g to 1.6 m 2 / g, 0.7 m 2 / g to 1.5 m 2 / g, 0.7 m 2 / g to 1.4 m 2 / g, 0.7 m 2 / g to 1.3 m 2 / g, 0.7 m 2 / g to 1.25 m 2 / g. Since the carbon material of the present application has a low specific surface area and low surface activity, it can reduce the consumption of active ions due to the formation of the SEI film, improve the initial Coulomb efficiency of the carbon material, and improve the cycle performance and storage performance of the secondary battery.

[0108] The specific surface area of the carbon material is a known meaning in this field and can be measured by known equipment and methods in this field. For example, referring to GB / T 19587-2017, it can be tested by the nitrogen gas adsorption specific surface area analysis test method and calculated by the BET (Brunauer Emmett Teller) method. The nitrogen gas adsorption specific surface area analysis test can be performed by a Tri-Star 3020 type specific surface area pore size analyzer manufactured by Micromeritics, USA.

[0109] In some embodiments, the volume distribution particle size Dv50 of the carbon material is 6.0 μm to 30.0 μm, optionally 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, optionally 17.0 μm to 42.0 μm.

[0111] When the volume distribution particle sizes Dv50 and / or Dv90 of the carbon material are within the above ranges, it is advantageous for improving the transport performance of active ions and electrons, so that 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 optionally 0.5 to 1.50. When the particle size distribution (Dv90 - Dv10) / Dv50 of the carbon material is within the above ranges, it is advantageous for increasing the compression density of the carbon material, so that the energy density of the secondary battery can be further increased, a reasonable tunnel structure can be formed between the particles of the negative electrode film layer, and it is also advantageous for improving the cycle performance and dynamic performance of the secondary battery.

[0113] In the present application, the volume distribution particle sizes Dv10, Dv50, and Dv90 of the carbon material have the known meanings in this field, and respectively indicate the particle sizes corresponding when the cumulative volume distribution percentage of the material reaches 10%, 50%, and 90%, and can be measured by the known equipment and methods in this field. For example, referring to GB / T 19077-2016 Laser Diffraction Method for Particle Size Distribution, it can be conveniently measured using a laser particle size analyzer. The test equipment may be a Mastersizer 3000 type laser particle size analyzer of Malvern Instruments Limited, 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 optionally 0.010 Ω·cm to 0.040 Ω·cm. When the powder resistivity of the carbon material is within the above ranges, it is advantageous for improving the electron transport performance, and the cycle performance and dynamic performance of the secondary battery can be further improved.

[0115] The powder resistivity of the carbon material is a known meaning in this field and can be measured by known devices and methods in this field. For example, referring to GB / T 30835-2014, it can be measured by the four-probe method using a powder resistivity tester (for example, it may be Suzhou Lattice ST2722 or Sansi Zongheng UTM7305). An exemplary measurement method is to weigh a certain amount of the measured sample powder, put it into a special mold, set the test pressure, and obtain the 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 20000 N is 1.70 g / cm 3 ~1.95 g / cm 3 and optionally 1.72 g / cm 3 ~1.92 g / cm 3 When the powder compression density of the carbon material is within the above range, the compression density of the negative electrode sheet can be increased, and further the energy density of the secondary battery can be increased. It is also beneficial for improving the transport performance of active ions and electrons and improving the cycle performance and dynamic performance of the secondary battery.

[0117] In this application, the powder compression density of the carbon material is a known meaning in this field and can be measured by known devices and methods in this field. For example, referring to GB / T 24533-2009, it can be measured by an electronic pressure tester (for example, it may be an UTM7305 type electronic pressure tester). As an exemplary test method, weigh 1 g of carbon material powder, put it into a mold with a bottom area of 1.327 cm 2 apply a pressure of 2000 kg (equivalent to 20000 N), hold the pressure for 30 s, then release the pressure and hold for 10 s, and then record and calculate the powder compression density of the carbon material at a pressure of 20000 N.

[0118] In some embodiments, the tap density of the carbon material is 0.80 g / cm 3 ~1.35 g / cm 3 and optionally 0.85 g / cm 3 ~1.30 g / cm 3That is. When the tap density of the carbon material is within the above range, the compression density of the negative electrode sheet can be increased, and further the energy density of the secondary battery can be increased. It is also advantageous for improving the transport performance of active ions and electrons, and the cycle performance and dynamic performance of the secondary battery.

[0119] The tap density of the carbon material is a known meaning in this field and can be measured by known devices and methods in this field. For example, referring to GB / T 5162-2006, it can be measured using a powder tap density tester. As the test equipment, Dandong Baite BT-301 can be used.

[0120] In some embodiments, the gram capacity of the carbon material is 350 mAh / g to 372 mAh / g, and optionally 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 the carbon material is a known meaning in this field and can be measured by known methods in this field. As an exemplary test method, a carbon material sample, styrene-butadiene rubber (SBR) as a binder, sodium carboxymethyl cellulose (CMC) as a thickener, and carbon black as a conductive agent are sufficiently stirred and mixed with an appropriate amount of deionized water as a 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 is uniformly coated on the surface of a copper foil, which is a negative electrode current collector, dried in an oven and used. After ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed at a volume ratio of 1:1:1 to obtain an organic solvent, LiPF6 is dissolved in the above organic solvent to prepare an electrolytic solution with a concentration of 1 mol / L. Then, a metal lithium sheet is used as a counter electrode, a polyethylene (PE) film is used as a separator, and a CR2430 coin cell is assembled in a glove box protected by argon gas. At 25 °C, first, the above-prepared coin cell is discharged at a constant current of 0.15 mA to 0.005 V, allowed to stand for 5 min, and then further discharged at a constant current of 10 μA to 0.005 V, and the initial discharge capacity of the coin cell is recorded. Then, it is charged at a constant current of 0.3 mA to 2.0 V, and the charge capacity of the coin cell is recorded. The ratio of the charge capacity of the coin cell to the mass of the carbon material sample is the gram capacity of the carbon material. Manufacturing method

[0122] The second aspect of the embodiment of the present application provides a method for manufacturing a carbon material capable of manufacturing the carbon material of the first aspect of the embodiment of the present application.

[0123] The method for manufacturing the carbon material includes step 1 of providing a raw material having a plurality of pore structures, step 2 of uniformly mixing the raw material and a filler at a predetermined ratio and then holding at a first temperature T1 for a first time t1 to obtain an intermediate, and step 3 of holding the obtained intermediate at a second temperature T2 for a second time t2 to obtain a carbon material. The carbon material includes a pore structure, and the carbon material satisfies 0.150 ≦ I D / I G ≦ 0.280, and I Drepresents the D peak intensity at 1350 ± 50 cm of the Raman spectrum of the carbon material, and I -1 represents the G peak intensity at 1580 ± 50 cm of the Raman spectrum of the carbon material. G In some embodiments, the raw material for manufacturing the carbon material includes natural graphite. Optionally, the natural graphite includes one or more of flaky graphite, natural spherical graphite, and microcrystalline graphite, and more preferably includes natural spherical graphite. -1 "Natural spherical graphite" means natural graphite having a spherical or quasi-spherical shape, and does not control all natural graphite particles into ideal spheres. In some embodiments, by performing pretreatment on flaky graphite, natural spherical graphite with a desired particle size and topography can be obtained. Optionally, the pretreatment includes processes such as crushing, classification, spheroidization, and purification.

[0124] In some embodiments, the topography of the raw material includes one or more of spherical or quasi-spherical shapes.

[0125] In some embodiments, the volume distribution particle size Dv50 of the raw material is 6.0 μm to 30.0 μm, and optionally 8.0 μm to 25.0 μm.

[0126] In some embodiments, the specific surface area of the raw material is 2.5 m

[0127] / g or more, and optionally 2.5 m

[0128] / g to 10.0 m 2 / g. When the specific surface area of the raw material is within the above range, it is advantageous for subsequent filling treatment to obtain a carbon material with a desired specific surface area, and it is also advantageous for the carbon material to have a high capacity and a high initial coulombic efficiency. Moreover, it is also advantageous for the carbon material to have better dynamic performance. 2 / g~10.0m 2 / g. When the specific surface area of the raw material is within the above range, it is advantageous for subsequent filling treatment to obtain a carbon material with a desired specific surface area, and it is also advantageous for the carbon material to have a high capacity and a high initial coulombic efficiency. Moreover, it is also advantageous for the carbon material to have better dynamic performance.

[0129] When the particle size of the raw material (e.g., volume distribution particle size Dv50 and / or specific surface area) is adjusted within the above range, it is possible to avoid agglomeration of the raw material in the subsequent manufacturing process as much as possible, thereby avoiding problems such as an increase in surface defects due to particle crushing and an increase in surface active sites as much as possible.

[0130] In some embodiments, the volume distribution particle size Dv50 of the filler is 6 μm or less, and optionally 1 μm to 6 μm, 1 μm to 5 μm, 2 μm to 5 μm, 3 μm to 5 μm. This is advantageous for the filler to be filled into the pore structure of the raw material after melting by heat, and is also advantageous for improving the dispersion uniformity 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 in the range consisting of any one of the numerical values 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 above. Optionally, 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, 125°C to 160°C, 125°C to 150°C, 125°C to 140°C, 130°C to 180°C, 130°C to 170°C, 130°C to 160°C, 130°C to 150°C, 130°C to 140°C.

[0132] In the process of study, the inventors have found that when the softening point temperature of the filler is within the above range, it is advantageous to adjust the number and / or size of pores in the external and internal regions of the carbon material within an appropriate range. Also, if the softening point temperature of the filler is too high, after the filler melts due to heat, it is difficult to flow and fill into the pore structure of the raw material, so that the internal defects of the particles cannot be effectively modified, and it is also impossible to effectively prevent the electrolyte from entering the pore structure inside the obtained carbon material particles. Furthermore, it affects the initial Coulomb efficiency, cycle performance and storage performance of the secondary battery. If the softening point temperature of the filler is too low, the filler contains many small molecule substances, and these small molecule substances are likely to volatilize due to heat. Therefore, after the filler melts due to heat, it is easy to flow and fill into the pore structure of the raw material. However, when heat treatment is performed in Step 2 and / or Step 3, the small molecule substances in the filler volatilize, so that the carbon actually remaining in the filling region cannot be effectively filled into the pore structure of the raw material, and an effective filling effect cannot be achieved. Or the carbon actually remaining in the filling region has many pore structures, and it is also impossible to reduce the consumption of active ions due to the formation of the SEI film, reduce the irreversible capacity loss of the secondary battery, and at the same time affect the cycle performance and storage performance of the secondary battery. This situation can be effectively avoided.

[0133] In some embodiments, the coke value of the filler is 25% - 50%, and optionally 30% - 42%. In the process of study, the inventors have found that when the coke value of the filler is within the above range, it is advantageous to adjust the number and / or size of pores in the external and internal regions of the carbon material within an appropriate range.

[0134] In some embodiments, the filler simultaneously satisfies that the softening point temperature is 120°C - 160°C and the coke value is 30% - 42%.

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

[0136] In some embodiments, the filler contains one or more of coal pitch, petroleum pitch, polymer compounds, and resins, and optionally contains 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 optionally (12~30):100, (14~28):100, (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. Also, 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, after the filler is melted by heat, it is difficult to flow and fill the pore structure of the raw material, and thus the internal defects of the particles cannot be effectively modified, and the electrolyte cannot be effectively prevented from penetrating into the pore structure inside the obtained carbon material particles, which affects the initial Coulomb efficiency, cycle performance, and storage performance of the secondary battery. Moreover, if the mass ratio of the filler to the raw material is too large, it is likely to cause the complete filling of the pore structure inside the raw material. In this case, the volume change of the obtained carbon material is large, the particles are more likely to be crushed, the consumption of active ions due to the formation of the SEI film increases, the irreversible capacity loss of the secondary battery increases, and if the mass ratio of the filler to the raw material is too large, a large amount of filler may 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 the situation where the gram capacity and compression density of the obtained carbon material decrease.

[0138] When parameters such as the type, softening point, coking value, and addition amount of the filler are adjusted within the above range, after the filler is melted by heat, its viscosity is not high, it maintains good fluidity, the raw material particles are not easily adhered, and the aggregation of the raw material particles in the subsequent manufacturing process can be reduced. Thereby, problems such as an increase in surface defects and an increase in surface active sites of the carbon material particles due to the depolymerization process can be reduced.

[0139] In some embodiments, in step 2, after uniformly mixing the raw material and the filler at a predetermined ratio, the temperature-raising process of raising the temperature to the first temperature T1 is a stepwise temperature-raising process, and optionally includes a first temperature-raising process, a second temperature-raising process, and a third temperature-raising process.

[0140] In some embodiments, in the first temperature-raising process, the temperature is raised to 200°C to 250°C and kept at this temperature for 1 h to 2 h.

[0141] In some embodiments, in the second temperature-raising process, the temperature is raised to 450°C to 550°C and kept at this temperature for 1 h to 2 h.

[0142] In some embodiments, in the third temperature-raising process, the temperature is raised to the first temperature T1 and kept at this temperature for the first time t1.

[0143] In the process of stepwise temperature-raising, first, the temperature is raised to 200°C to 250°C. Since the heating temperature is higher than the softening point temperature of the filler, at this time, the filler is melted and softened by heat, and can be kept at this temperature for 1 h to 2 h to be fluidly filled into the pore structure of the raw material. Then, the temperature is raised to 450°C to 550°C. At this time, the melted and softened filler undergoes a carbonization reaction and gradually becomes a char state, turning into a viscous liquid or solid. Thereby, it is avoided that the filler enters all the pore structures of the raw material. Finally, the temperature is raised to the first temperature. At this time, the filler undergoes a carbonization reaction, whereby the pore structure occupied by the filler can be effectively filled.

[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 consisting of any value such as 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 above.

[0145] In the process of investigation, the inventors found that when the heating rate is within the above range, it is advantageous to adjust the number and / or size of pores in the external and internal regions of the carbon material within 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 consisting of 700 °C, 750 °C, 800 °C, 850 °C, 900 °C, 950 °C, 1000 °C, 1050 °C, 1100 °C, 1200 °C or any numerical value thereabove. Optionally, the first temperature T1 is 720 °C to 1100 °C.

[0150] In the process of investigation, the inventors found that when the first temperature is within the above range, it is advantageous to adjust the number and / or size of pores in the external and internal regions of the carbon material within an appropriate range. Also, if the first temperature is too low, the filler may not be completely converted into carbon, and then, by continuously decomposing into small molecule substances during the heat treatment in step 3, the carbon actually remaining in the filling region has many pore structures and cannot effectively modify the defects inside the particles, nor can it effectively prevent the electrolyte from infiltrating into the pore structures inside the obtained carbon material particles, which affects the initial Coulombic efficiency, cycle performance and storage performance of the secondary battery. Moreover, if the first temperature is too high, the situation of increased energy consumption in the manufacturing process of the carbon material can be effectively avoided.

[0151] In some embodiments, the first time t1 is from 1 h to 5 h. For example, the first time t1 may be a range consisting of any value such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h or more. Optionally, the first time t1 is from 2 h to 4 h.

[0152] In the process of research, the inventors found that when the first time is within the above range, it is advantageous to adjust the number and / or size of pores in the external and internal regions of the carbon material within an appropriate range. Also, if the first time is too short, the filler cannot effectively fill the carbon material particles, so there is a lot of carbon actually remaining in the filling region with many pore structures and it cannot effectively modify the defects inside the particles, nor can it effectively prevent the electrolyte from entering the pore structure inside the obtained carbon material particles, which affects the initial Coulombic efficiency, cycle performance and storage performance of the secondary battery. Moreover, if the first time is too long, the situation of increased energy consumption in the manufacturing process of the carbon material can be effectively avoided.

[0153] In some embodiments, in step 2, the heat treatment may be performed 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, the first temperature, the first time, the heating process, etc. within the above range is advantageous for manufacturing a carbon material having a desired structure. For example, it is advantageous for the carbon material to satisfy S2 > S1, and optionally 1.5 ≤ S2 / S1 ≤ 450, 2 ≤ S2 / S1 ≤ 400.

[0156] In some embodiments, the second temperature T2 is 1800°C to 2600°C. For example, the second temperature may be in the range consisting of any value such as 1800°C, 1900°C, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, 2500°C, 2600°C or above. Optionally, the second temperature T2 is 1860°C to 2560°C, 1860°C to 2520°C, 1860°C to 2480°C, 1860°C to 2450°C, 1860°C to 2410°C, 1860°C to 2370°C, 1860°C to 2330°C, 1900°C to 2560°C, 1900°C to 2520°C, 1900°C to 2480°C, 1900°C to 2450°C, 1900°C to 2410°C, 1900°C to 2370°C, 1900°C to 2330°C, 1970°C to 2560°C, 1970°C to 2520°C, 1970°C to 2480°C, 1970°C to 2450°C, 1970°C to 2410°C, 1970°C to 2370°C, 1970°C to 2330°C, 2030°C to 2560°C, 2030°C to 2520°C, 2030°C to 2480°C, 2030°C to 2450°C, 2030°C to 2410°C, 2030°C to 2370°C, 2030°C to 2330°C.

[0157] During the study process, the inventors found that when the second temperature is within the above range, it is advantageous for adjusting the irregularity of the carbon material, the carbon material has a stable structure, and it is also advantageous to avoid particle crushing as much as possible. When the second temperature is too low, the content of irregular carbon in the obtained carbon material is high, so the defect content of the carbon material, especially the content of surface defects, is high, which affects the initial Coulomb efficiency and storage performance of the carbon material. When the second temperature is too high, the content of irregular carbon in the obtained carbon material is too low, so both the crystallinity and graphitization degree of the carbon material are high. At this time, it is disadvantageous for the rapid desorption and insertion of active ions, and the volume change of the carbon material during the charge-discharge process is large, so the risk of carbon material particle crushing also increases, thus effectively avoiding the situation of affecting the cycle performance and storage performance of the secondary battery.

[0158] In some embodiments, the second time t2 is 1.5 h to 6 h. For example, the second time t1 may be in the range consisting of any value such as 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h, 6 h or more. Optionally, the second time t2 is 2 h to 5 h.

[0159] In the process of research, the inventors found that when the second time is within the above range, it is advantageous for adjusting the irregularity of the carbon material, the carbon material has a stable structure, and it is also advantageous to avoid particle crushing as much as possible. When the second time is too short, the content of irregular carbon in the obtained carbon material is high, so the content of defects in the carbon material, especially the content of surface defects, is high, which affects the gram capacity and initial Coulomb efficiency of the carbon material. When the second time is too long, the content of irregular carbon in the obtained carbon material is too low, so both the crystallinity and graphitization degree of the carbon material are high. In this case, it is disadvantageous for the rapid desorption and insertion of active ions, and the volume change of the carbon material during the charge-discharge process is large, so the risk of carbon material particle crushing also increases, thus effectively avoiding the situation of affecting 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 graphitization furnace, an Acheson-type graphitization furnace, a continuous graphitization furnace or an internal series graphitization furnace.

[0161] In some embodiments, in step 3, the atmosphere of the intermediate frequency furnace and the 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 the second time within the above range, it is advantageous to adjust the content of irregular carbon in the carbon material within an appropriate range, and the I of the carbon material D / I GIt is advantageous to keep it within an appropriate range, and it is also advantageous for S2 / S1 of the carbon material to meet within an appropriate range.

[0163] The method for manufacturing the carbon material of the present application has simple steps, high safety, does not require performing a predetermined pressure or evacuation treatment, and does not require adding a depolymerization step during the heat treatment process. The carbon material manufactured in the present application has a small volume expansion, high structural stability, low surface activity, and can also have a high gram capacity, high initial Coulomb efficiency, and small volume change. It can also endow the secondary battery with high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0164] The manufacturing method of the present application has low cost, high practicality, and is suitable for large-scale production. Secondary battery

[0165] The third aspect of the embodiment of the present application provides a secondary battery.

[0166] The present application does not particularly limit the type of the secondary battery. For example, the secondary battery may be a lithium-ion battery or the like. Usually, the secondary battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte, and the like. During the charge and discharge process of the secondary battery, active ions reciprocally insert and desorb between the positive electrode sheet and the negative electrode sheet, and the electrolyte plays a role of conducting active ions between the positive electrode sheet and the negative electrode sheet. The present application does not particularly limit the type of the electrolyte, and it can be selected according to actual needs. For example, the electrolyte may be at least one selected from a solid electrolyte and a liquid electrolyte (i.e., an electrolytic solution). In a secondary battery using an electrolytic solution and a secondary battery using a solid electrolyte, a separator for performing an isolation role provided between the positive electrode sheet and the negative electrode sheet may further be included. [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 surfaces facing each other in its thickness direction, and the negative electrode film layer is provided on either one or both of the two opposing surfaces of the negative electrode current collector.

[0168] In some embodiments, the negative electrode film layer includes the carbon material of the first aspect of the embodiments of the present application or the carbon material manufactured by the method described in the second aspect of the embodiments of the present application. Thereby, the secondary battery can 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 include other negative electrode active materials other than the above carbon material. In some embodiments, the other negative electrode active materials include, but are not limited to, one or more of 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 silicon alone, silicon oxide, silicon-carbon composite, silicon-nitrogen composite, and silicon alloy material. The tin-based material may include one or more of tin alone, tin oxide, and tin alloy material.

[0170] In some embodiments, the negative electrode film layer may optionally further include a negative electrode conductive agent. In the present application, the type of the negative electrode conductive agent is not particularly limited. For example, the negative electrode conductive agent can include one or more of 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 include a negative electrode binder. The present application does not particularly limit the type of the negative electrode binder. By way of example, the negative electrode binder may include one or more of styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (e.g., polyacrylic acid PAA, polymethacrylic acid 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 include other auxiliaries. By way of example, the other auxiliaries may include, for example, a thickener such as sodium carboxymethyl cellulose (CMC), and may include a PTC thermistor material.

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

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

[0175] The negative electrode sheet does not exclude other additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet according to the present application further includes a conductive undercoat layer (for example, composed 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. In some embodiments, the negative electrode sheet according to the present application 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 surfaces facing each other in its thickness direction, and the positive electrode film layer is provided on either one or both of the two opposing surfaces of the positive electrode current collector.

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

[0178] The positive electrode film layer usually includes a positive electrode active material, an optional binder, and an optional conductive agent. The positive electrode film layer is usually formed by applying a positive electrode slurry to the positive electrode current collector, drying, and cold pressing. The positive electrode slurry is usually formed by dispersing a positive electrode active material, an optional conductive agent, an optional binder, and an optional other component in a solvent and stirring uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP). As an example, the binder used in the positive electrode film layer may include any one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), a terpolymer of vinylidene fluoride-tetrafluoroethylene-propylene, a terpolymer of vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene, a copolymer of tetrafluoroethylene-hexafluoropropylene, and a fluorine-containing acrylate resin. As an example, the conductive agent used in the positive electrode film layer includes any one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dot, carbon nanotube, graphene, and carbon nanofiber.

[0179] As the positive electrode active material, a positive electrode active material for a secondary battery known in the art can be adopted.

[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 O2, LiFePO4, and LiMnPO4.

[0183] In the present application, the modified compound of each of the above cathode active materials is obtained by performing doping modification and / or surface coating modification on the cathode active material. [Electrolyte]

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

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

[0186] When the secondary battery of the present application is a lithium-ion battery, for example, the electrolyte salt may contain one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium difluoromethanesulfonimide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluoroborate oxalate (LiDFOB), lithium diborate oxalate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodiphosphate oxalate (LiDFOP), and lithium tetrafluoroborate oxalate (LiTFOP).

[0187] The type of the solvent is not particularly limited and can be selected according to actual demands. In some embodiments, by way of example, the organic solvent may include one or more of ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

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

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

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

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

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

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

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

[0195] In some embodiments, as shown in FIG. 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 the side plates surround to form an accommodation chamber. The case 51 has an opening communicating with the accommodation chamber, and the bar plate 53 closes the opening so as to close the accommodation chamber. The positive electrode sheet, the negative electrode sheet, and the separator can form an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged in the accommodation chamber. The electrolytic solution infiltrates 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 manufacturing method of the secondary battery of the present application is known. In some embodiments, a secondary battery can be formed by assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolytic solution. For example, a positive electrode sheet, a separator, and a negative electrode sheet can be formed into an electrode assembly by a winding process or a lamination process. The electrode assembly is placed in an exterior package, dried, and then the electrolytic solution is injected. After passing through processes such as vacuum encapsulation, standing, formation, and shaping, a secondary battery can be obtained.

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

[0198] FIG. 5 is a schematic diagram of a battery module 4 as an example. As shown in FIG. 5, in the battery module 4, a plurality of secondary batteries 5 may be arranged in sequence along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Further, the plurality of secondary batteries 5 may be fixed by a fastener.

[0199] Optionally, the battery module 4 further includes an external case having an accommodation space, and the plurality of secondary batteries 5 are accommodated in the accommodation space.

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

[0201] FIGS. 6 and 7 are schematic diagrams of a battery pack 1 as an example. As shown in FIGS. 6 and 7, the battery pack 1 may include a battery case and a plurality of battery modules 4 provided in the battery case. The battery case includes an upper case 2 and a lower case 3, and the upper case 2 covers the lower case 3 to form a sealed space for accommodating the battery module 4. The plurality of battery modules 4 may be arranged in the battery case in any manner. Power consumption device

[0202] The present application further provides a power consumption device including at least one of a secondary battery, a battery module, or a battery pack of the present application. The secondary battery, battery module, or battery pack may be used as a power source of the power consumption device or as an energy storage means of the power consumption device. The power consumption device may be a mobile device (e.g., a mobile phone, a tablet, a notebook computer, etc.), an electric vehicle (e.g., a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, an electric bicycle, an electric scooter, an electric golf cart, an electric truck, etc.), a train, a ship, and a satellite, an energy storage system, etc., but is not limited thereto.

[0203] The power consumption device can select a secondary battery, a battery module, or a battery pack according to demand.

[0204] FIG. 8 is a schematic diagram of a power consumption device as an example. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, a plug-in hybrid electric vehicle, etc. In order to meet the requirements of high output and high energy density of this power consumption device, a battery pack or a battery module can be adopted.

[0205] Another example of the power consumption device may be a mobile phone, a tablet computer, a notebook computer, etc. This power consumption device is generally required to be thin, and a secondary battery can be adopted as a power source. Example

[0206] The following examples illustrate the content of the present application in more detail. However, these examples are merely illustrative explanations, and it is obvious to those skilled in the art that various modifications and changes can be made within the scope of the disclosure of the present application. Unless otherwise specified, all parts, percentages, and ratio values described in the following examples are all based on mass standards. In addition, all reagents used in the examples may be commercially available or synthesized according to conventional methods, and can be used as they are without further treatment. Also, any of the devices used in the examples may be commercially available. Example 1 (1) Preparation of carbon material

[0207] Step 1: Mechanical grinding, classification, spheroidization, and purification treatment were performed on 100-mesh flaky graphite 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.

[0208] Step 2: The obtained natural spherical 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 min. After that, the mixed material was put into a roller hearth kiln, heated to 220 °C at a rate of 5 °C / min and held for 1 h (the first heating process), then heated to 500 °C at a rate of 5 °C / min and held for 2 h (the second heating process), and finally heated to 1000 °C at a rate of 5 °C / min and held for 2 h (the third heating process). After completion, it was cooled to room temperature to obtain an intermediate.

[0209] Step 3: The obtained intermediate was put into an Acheson-type graphitization furnace, heated to 2400 °C and held for 2 h. After completion, it was demagnetized and sieved to obtain a carbon material.

[0210] Referring to GB / T 19587-2017, it was tested by the nitrogen gas adsorption specific surface area analysis measurement method, and the specific surface area of the carbon material was calculated by the BET (Brunauer Emmett Teller) method. The result was 1.07 m 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, using a metal lithium sheet as the counter electrode and a polyethylene (PE) film as the separator, a CR2430 type coin cell was assembled in a glove box protected by argon gas. (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, and after drying, the same electrolyte as the coin cell produced above was injected. Through processes such as vacuum sealing, standing, forming, and capacity measurement, 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] The 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. 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 at a mass ratio of 100:20 for 30 min, and then the mixed material was graphitized at 3200 °C for 10 h. After completion, it was cooled to room temperature to obtain a carbon material. Comparative Example 3

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

[0222] The 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. 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 at a mass ratio of 100:20 for 30 min, and then the mixed material was carbonized at 1300 °C for 2 h. After completion, it was cooled to room temperature to obtain a carbon material. Comparative Example 4

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

[0224] The original graphite ore was processed into small particles by mechanical treatment. To remove impurities, it was treated with a strong alkali 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 grinding and secondary grinding, i.e., machining, were performed. Next, after acid treatment, washing, and drying, purification was carried out to obtain high-purity spherical natural graphite. The obtained spherical natural graphite is damaged on the surface during mechanical pulverization and attrition, and chemical reactive groups are formed after strong alkali / strong acid washing. During spheroidization, defects are generated in the natural graphite due to machining. For carbon coating, pitch (softening point temperature 148 °C, volume distribution particle size Dv50 of 4.5 μm, coke value 40%) was dry-coated on the surface of the damaged high-purity solid-phase natural graphite by a dry method, carbonized at 1200 °C for 24 h in an inert gas atmosphere to perform carbon coating, and then pulverized, sieved, and iron removed to obtain a carbon material. Comparative Example 5

[0225] 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.

[0226] The flaky graphite of 100 mesh was subjected to mechanical pulverization, classification, spheroidization, and purification treatments 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. The obtained natural spherical graphite, powdered medium-temperature pitch (content of quinoline-insoluble matter 1%, softening point temperature 80 °C), and toluene accounting for 0.5% of the mass of the pitch were mixed at a mass ratio of 1:1, then put into a reaction kettle, the reaction kettle was sealed, heated to 200 °C at 3 °C / min, kept at a constant temperature for 4 h, the pressure was maintained at 0.1 MPa, then the sample was taken out, after the sample was cooled, it was put into a furnace and graphitized at 3000 °C. The sample after graphitization was pulverized and classified to obtain a carbon material. Comparative Example 6

[0227] 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.

[0228] The flaky graphite with 100 mesh 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, with a heating rate of 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 internal pores. Examples 2 - 7 and Comparative Example 7

[0230] The manufacturing methods of the half-cell and 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 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 of the half cell and the full cell are similar to those of Example 3, except that the parameters in Step 2 of the carbon material manufacturing process are adjusted. Specifically, refer to Table 3.

[0235] [Table 3] Examples 24 to 28

[0236] The manufacturing methods of the half cell and the full cell are similar to those of Example 1, except that the parameters in Step 1 of the carbon material manufacturing process are adjusted. Specifically, refer to Table 4.

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

[0238] The preparation binder is uniformly mixed with the carbon material powder and then applied to the copper foil, dried at 60 °C for 30 min to prepare. The sample is cut into a size of 6 mm × 6 mm and attached to the sample stage of a CP type argon ion cross-section polisher, and the sample is cut using a plasma beam to obtain the cross-section of the carbon material, and the cross-section of the carbon material passes through the center of the carbon material particles. As the tester, an IB-09010 CP type argon ion cross-section polisher of JEOL Ltd., Japan can be used.

[0239] The cross-section of the carbon material was scanned using a scanning electron microscope. The test can refer to JY / T010-1996. The test equipment may be a Sigma 300 type scanning electron microscope of ZEISS, Germany.

[0240] A region that extends from the particle surface of the carbon material to the particle interior at a distance of 0.25L is defined as the external region, and the region inside the external region is defined as the internal region, where L represents the minor axis length of the carbon material particles. Using image processing software, the total pore area S1 of the outer region of the carbon material and the total pore area S2 of the inner region of the carbon material were calculated. The image processing software may be AVIZO. (2) Test of the Raman spectrum of the carbon material

[0241] Using a Raman spectrometer, the measurement conditions were as follows: the excitation wavelength was 532 nm, the diffraction grating had 600 lines, the objective lens had a magnification of 50 times, the integration time was 10 s, the number of integrations was 3 times, and area scanning was performed to obtain the D-peak and G-peak intensities at 100 points, and the I D / I G was calculated. The maximum and minimum 30 I D / I G were removed, and the average value of the remaining 40 points was the I D / I G of the carbon material. The test equipment may be a Horiba LabRAM HR800 Raman spectrometer. (3) Test of the initial Coulomb efficiency of the carbon material

[0242] At 25 °C, first, the above-prepared coin cell was discharged at a constant current of 0.15 mA to 0.005 V, allowed to stand for 5 minutes, and then further discharged at a constant current of 10 μA to 0.005 V. The initial charge capacity of the coin cell was recorded. Then, it was charged at a constant current of 0.3 mA to 2.0 V, and the initial charge capacity of the coin cell was recorded.

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

[0244] At 45°C, the above-prepared secondary battery was charged at a constant current of 1C to the upper cut-off voltage (corresponding to 100% SOC), and then charged at a constant voltage until the current reached 0.05C. After standing for 5 minutes, the secondary battery was discharged at a constant current of 1C to the lower cut-off voltage (corresponding to 0% SOC), and 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 1 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) Test of the storage performance of the secondary battery

[0245] At 25°C, the above-prepared secondary battery was charged at a constant current of 1C to the upper cut-off voltage (corresponding to 100% SOC), and then charged at a constant voltage until the current reached 0.05C. After standing for 5 minutes, the secondary battery was discharged at a constant current of 1C to the lower cut-off voltage (corresponding to 0% SOC), and the discharge capacity at this time was recorded, which is the discharge capacity before storage.

[0246] At 25°C, the above-prepared secondary battery was charged at a constant current of 1C to the upper cut-off voltage (corresponding to 100% SOC), and then charged at a constant voltage until the current reached 0.05C. Then, it was placed in a constant-temperature bath at 60°C and stored for 150 days. The capacity retention rate (%) of the secondary battery after storage at 60°C for 150 days = discharge capacity after storage / discharge capacity before storage × 100%.

[0247]

Table 5

[0248] The parameters such as the specific surface area, volume distribution particle size, powder resistivity, powder compression density, tap density, and graphitization degree of the carbon materials manufactured 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 manufactured in the examples of this application were all 0.150 ≦ I D / I GSatisfies ≦0.280. In this case, on the one hand, it can effectively reduce the content of irregular carbon, lower the surface activity of the carbon material, and reduce the consumption of active ions due to the formation of the SEI film on the particle surface. On the other hand, it can endow the carbon material with a stable structure and avoid particle crushing as much as possible. Therefore, the carbon material according to the present application has a small volume expansion, high structural stability, low surface activity, and can endow the battery with high gram capacity, high initial Coulomb efficiency, high capacity retention rate after cycling, and high capacity retention rate after storage.

[0250] The Raman spectra of the carbon materials produced in Comparative Examples 1 to 7 all satisfy 0.150 ≦ I D / I G Do not satisfy ≦0.280, and none of them can endow the battery with high gram capacity, high initial Coulomb efficiency, high capacity retention rate after cycling, and high capacity retention rate after storage. The I D / I G of the carbon materials produced in Comparative Examples 1, 3 to 4, and 6 are all greater than 0.280. In this case, the content of irregular carbon in the carbon material is high, the surface active sites of the carbon material are many, and the content of surface defects is high. Therefore, the irreversible consumption of active ions is large, and it is impossible to endow the battery with high gram capacity, high initial Coulomb efficiency, high capacity retention rate after cycling, and high capacity retention rate after storage. The I D / I G of the carbon materials produced in Comparative Examples 2, 5, and 7 are all less than 0.150. In this case, the content of irregular carbon on the surface of the carbon material particles is low, and the surface active sites of the particles are few. However, the rapid desorption and insertion ability of active ions becomes poor, and the volume change of the carbon material during the charge and discharge process of the battery is large. Therefore, the carbon material particles are more likely to be crushed, and it is also impossible to endow the battery with high gram capacity, high initial Coulomb efficiency, high capacity retention rate after cycling, and high capacity retention rate after storage.

[0251] Summarizing the test results in Table 5, when the carbon material further satisfies S2 > S1, selectively satisfies 1.5 ≤ S2 / S1 ≤ 450, and more selectively satisfies 2 ≤ S2 / S1 ≤ 400, it can be seen that 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. At this time, the carbon material particles further have the characteristics that the number of pores in the internal region is large and / or the pore size is large, but the number of pores in the external 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 and irreversible capacity loss of the secondary battery. Since the number of pores in the external region of the carbon material is small and / or the pore size is small, the carbon material particles have a more stable structure, and the electrolyte can be avoided from penetrating into the pore structure inside the carbon material particles as much as possible, so the occurrence of side reactions can be reduced, and the consumption of active ions due to the formation of the SEI film inside the particles can be reduced. Thereby, the gram capacity, initial Coulomb efficiency, capacity retention rate after cycling, and capacity retention rate after storage of the battery can be further improved.

[0252] The carbon materials produced in Comparative Examples 1 to 6 do not satisfy S2 > S1.

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

[0254] The carbon materials produced in Comparative Examples 2 to 4 are those with a carbon layer coating formed on the surface of natural spherical graphite. However, the carbon layer only exists on the surface of natural spherical graphite, and the filling effect cannot be realized. Moreover, the carbon layer cannot effectively prevent the electrolyte from penetrating into the pore structure inside the particles, and the improvement effect on the initial Coulomb efficiency, cycle performance, and storage performance of the battery is limited.

[0255] In Comparative Example 5, when manufacturing the carbon material, the softening point temperature of the filler used was low, and small molecule substances in the filler volatilized during the graphitization treatment. Therefore, the carbon actually remaining in the filling region could not effectively fill the pore structure of the natural spherical graphite, and an effective filling effect could not be realized. Moreover, the electrolyte could not be effectively prevented from penetrating into the pore structure inside the particles. Furthermore, the improvement effect on the cycle performance and storage performance of the battery was limited.

[0256] In Comparative Example 6, when manufacturing the carbon material, the filler was filled into all the pore structures inside the natural spherical graphite particles by evacuation, and there was no pore structure inside the carbon material particles obtained at this time. As a result, the volume change occurring during the desorption and insertion process of the active ions of the carbon material was large, and the particles were more likely to be crushed. Furthermore, the improvement effect on the cycle performance and storage performance of the battery was limited.

[0257] It should be noted that the present application is not limited to the above embodiments. The above embodiments are illustrative, and those having a configuration substantially the same as the technical idea and similar effects within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, various modifications conceived by those skilled in the art within the scope not departing from the gist of the present application and other forms constructed by combining some components in the embodiments are also included in the scope of the present application.

Claims

1. having a pore structure and satisfying 0.150 ≦ I Ｄ / I Ｇ ≦ 0.280 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, Carbon material.

2. 0.152 ≤ I Ｄ / I Ｇ ≤ 0.280, and optionally, 0.155 ≤ I Ｄ / I Ｇ ≤ 0.220 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, and optionally includes one or more pore structures with a pore area of 0.15 μm ２ to 2.0 μm ２ or more. The carbon material according to Claim 1 or 2.

4. The carbon material includes an outer region and an inner region located inside the outer region. The outer region is a region formed by extending 0.25L from the particle surface of the carbon material to the particle interior, where L is the short axis length of the carbon material particles. Let the total pore area of the outer region be S １ and the total pore area of the inner region be S ２ . When this is the case, S ２ > S １ is satisfied The carbon material according to any one of Claims 1 to 3.

5. 1.5 ≤ S ２ / S １ ≤ 450, and optionally, 2 ≤ S ２ / S １ ≤ 400 The carbon material according to Claim 4.

6. 0.01 μm ２ ≤ S １ ≤ 5.0 μm ２ wherein, optionally, 0.02 μm ２ ≤ S １ ≤ 4.5 μm ２ and / or 2.5 µm ２ ≤ S ２ ≤ 25.0 µm ２ and optionally, 3.0 µm ２ ≤ S ２ ≤ 22.5 µm ２ is The carbon material according to Claim 4 or 5.

7. L ≧ 4 μm, and optionally, 4 μm ≦ L ≦ 20 μm, The carbon material according to any one of Claims 4 to 6.

8. The area of the pore structure in the outer region of the carbon material is 0.15 μm ２ or less, and optionally, 0.10 μm ２ or less, and / or The internal region of the carbon material includes one or more pore structures with an area of 0.15 μm ２ or more, and optionally includes one or more pore structures with an area of 0.15 μm ２ to 2.0 μm ２ or more. The carbon material according to any one of Claims 4 to 7.

9. Let the interlayer distance of the external region of the carbon material be d １ and the interlayer distance of the internal region of the carbon material be d ２ In the case, the carbon material satisfies d １ ≧d ２ and satisfies Optionally, d １ > d ２ , Optionally, d １ is from 0.33565 nm to 0.33620 nm, Optionally, d ２ is from 0.33557 nm to 0.33589 nm, The carbon material according to any one of Claims 4 to 8.

10. The carbon material satisfies at least one of the following: (1) The specific surface area of the carbon material is 2.1 m ２ / g or less, and optionally 0.7 m ２ / g to 1.8 m ２ / g, and (2) The volume distribution particle size Dv50 of the carbon material is 6.0 μm to 30.0 μm, and optionally 8.0 μm to 25.0 μm, (3) The volume distribution particle size Dv90 of the carbon material is 16.0 μm to 45.0 μm, and optionally 17.0 μm to 42.0 μm, (4) The particle size distribution (Dv90 - Dv10) / Dv50 of the carbon material is 1.55 or less, and optionally 0.5 to 1.

50. The carbon material according to any one of Claims 1 to 9.

11. The carbon material satisfies at least one of the following: (1) The powder resistivity of the carbon material at a pressure of 8 MPa is 0.006 Ω·cm to 0.051 Ω·cm, and optionally 0.010 Ω·cm to 0.040 Ω·cm, (2) The powder compression density of the carbon material under a pressure of 20,000 N is 1.70 g / cm ３ to 1.95 g / cm ３ and optionally 1.72 g / cm ３ to 1.92 g / cm ３ and (3) The tap density of the carbon material is 0.80 g / cm ３ ~1.35 g / cm ３ and optionally 0.85 g / cm ３ ~1.30 g / cm ３ and (4) The gram capacity of the carbon material is 350 mAh / g to 372 mAh / g, and optionally 353 mAh / g to 371 mAh / g, (5) The graphitization degree of the carbon material is 92.0% to 98.0%, and optionally 92.5% to 97.6%, (6) The topography of the carbon material includes one or more of massive, spherical, and quasi-spherical. The carbon material according to any one of Claims 1 to 10.

12. A method for manufacturing a carbon material, comprising: Step 1 of providing a raw material having a plurality of pore structures; After uniformly mixing the raw materials and the filler at a predetermined ratio, maintain the temperature at the first temperature T １ for the first time period t １ to obtain an intermediate in step 2; The obtained intermediate is maintained at a second temperature T ２ for a second time t ２ to obtain a carbon material in Step 3, and the method includes The carbon material includes a pore structure, and 0.150 ≤ I Ｄ / I Ｇ ≤ 0.280 is satisfied, 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. A method for manufacturing a carbon material.

13. The raw material satisfies at least one of the following: (1) The raw material contains natural graphite, and optionally, the natural graphite contains one or more of flake graphite, natural spherical graphite, and microcrystalline graphite, (2) The volume distribution particle size Dv50 of the raw material is 6.0 μm to 30.0 μm, and optionally 8.0 μm to 25.0 μm. (3) The specific surface area of the raw material is 2.5 m ２ / g or more, and optionally 2.5 m ２ / g to 10.0 m ２ / g, The method according to Claim 12.

14. The filler satisfies at least one of the following: (1) The softening point temperature of the filler is 100°C to 180°C, optionally 120°C to 160°C; (2) The coke value of the filler is 25% to 50%, optionally 30% to 42%; (3) The volume distribution particle size Dv50 of the filler is 6 μm or less, optionally 1 μm to 5 μm. The method according to claim 12 or 13.

15. The filler contains one or more of coal pitch, petroleum pitch, polymer compounds, and resins, and optionally contains one or more of coal pitch and petroleum pitch. The method according to claim 14.

16. The mass ratio of the filler to the raw material is (10 to 32):100, optionally (15 to 25):

100. The method according to any one of claims 12 to 15.

17. After uniformly mixing the raw material and the filler at a predetermined ratio, the temperature is raised to the first temperature T １ The temperature raising step of raising the temperature to is a stepwise temperature raising step, and optionally includes a first temperature raising step, a second temperature raising step, and a third temperature raising step The method according to any one of claims 12 to 16.

18. In the first heating step, the temperature is raised to 200°C to 250°C and held at this temperature for 1 h to 2 h, and / or In the second heating step, the temperature is raised to 450°C to 550°C and held at this temperature for 1 h to 2 h, and / or The third temperature-rising step raises the temperature to the first temperature T １ and holds the temperature at that level for a first time t １ for heat preservation. The method according to claim 17.

19. The temperature is raised to the first temperature T at a rate of 1 °C / min to 10 °C / min. １ ​ The method according to any one of claims 12 to 18.

20. The first temperature T １ is from 700°C to 1200°C, optionally from 720°C to 1100°C, and / or The first time t １ is from 1 h to 5 h, and optionally from 2 h to 4 h The method according to any one of claims 12 to 19.

21. the second temperature T ２ is from 1800°C to 2600°C, optionally from 1900°C to 2450°C, and / or The second time t ２ is 1.5 h to 6 h, and optionally 2 h to 5 h The method according to any one of claims 12 to 20..

22. Comprising a negative electrode sheet, The negative electrode sheet contains the carbon material according to any one of claims 1 to 11 or the carbon material manufactured by the method according to any one of claims 12 to 21. Secondary battery.

23. Comprising the secondary battery according to claim 22, Power consumption device.

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