Carbon material, its manufacturing method, and secondary battery and power consumption device containing the carbon material

Abstract

The present application provides a carbon material, a method for producing the same, and a secondary battery and a power consumption device including the same, wherein the carbon material has a pore structure, and the total pore volume of the carbon material is denoted as V and the powder compressed density of the carbon material at a pressure of 50,000 N is denoted as P. The carbon material has a pore size of 4.1 × 10 ―3 ≦V×P≦12.0×10 -3 and the total pore volume V of the carbon material is expressed in cm 3 / g, and the powder compressed density P of the carbon material at a pressure of 50,000 N is in g / cm 3 The carbon material provided in the present application can provide a secondary battery with high initial coulombic efficiency, high energy density, and good cycle performance and storage performance all at the same time.

Description

[Technical Field]

[0001] The present application belongs to the field of battery technology, and specifically relates to a carbon material and a method for manufacturing the same, as well as a secondary battery and a power consuming device containing the carbon material. [Background technology]

[0002] In recent years, secondary batteries have been widely used in storage power systems such as hydroelectric, thermal, wind, and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. As the range of secondary battery applications becomes increasingly wider, people are placing stricter demands on the performance of secondary batteries, such as high energy density and long service life. The negative electrode active material is an important component of secondary batteries and affects their performance. Currently, negative electrode active materials mainly contain graphite. However, a problem with conventional technology is that high-capacity graphite does not simultaneously have high initial coulombic efficiency, making it difficult for secondary batteries to simultaneously achieve good cycle performance and storage capacity. Summary of the Invention

[0003] The present application aims to provide a carbon material that can provide a secondary battery with high initial coulombic efficiency, high energy density, and good cycle performance and storage performance, a method for producing the same, and a secondary battery and power consuming device that include the carbon material.

[0004] In a first aspect of the present application, a carbon material is provided, the carbon material comprising a pore structure, wherein a total pore volume of the carbon material is denoted as V and a powder compaction density of the carbon material at a pressure of 50,000 N is denoted as P, and the carbon material has a powder compaction density of 4.1 × 10 -3 ≦V×P≦12.0×10 -3 and the total pore volume V of the carbon material is expressed in cm 3 / g, and the powder compressed density P of the carbon material at a pressure of 50,000 N is in g / cm 3 is.

[0005] The inventor of the present application discovered that the carbon material was 4.1 × 10 -3 ≦V×P≦12.0×10 -3 The inventors have discovered that when these requirements are met, a secondary battery can achieve high initial coulombic efficiency, high energy density, and good cycle and storage performance. According to the inventors' research, in this case, the carbon material can have an appropriate structure, with few pores in the carbon material particles, while at the same time retaining some pores with relatively large pore areas. This relatively large pore area provides the expansion space necessary for volumetric changes in the carbon material particles, thereby reducing the risk of new interface formation due to damage to the carbon material particles, further reducing the occurrence of side reactions, reducing irreversible capacity loss in the secondary battery, and improving the cycle and storage performance of the secondary battery. The small pore structure in the particles allows the carbon material particles to have a stable structure, minimizing the infiltration of the electrolyte into the pore structure inside the carbon material particles. This reduces the occurrence of side reactions, reduces the consumption of active ions due to the formation of an SEI film inside the particles, and further improves the initial coulombic efficiency of the carbon material, thereby further improving the cycle and storage performance of the secondary battery. Therefore, the carbon material provided in the present application can effectively reduce the irreversible capacity loss of a secondary battery, improve the capacity development characteristics of the secondary battery, and enable the secondary battery to achieve both high initial coulombic efficiency, high energy density, and good cycle performance and storage performance.

[0006] In any embodiment of the present application, 4.3×10 -3 ≦V×P≦10.0×10 -3 and preferably 4.4 x 10 -3 ≦V×P≦8.0×10 -3 When the V×P of the carbon material is within the above range, the secondary battery can be made to have a high initial coulombic efficiency, a high energy density, and good cycle performance and storage performance all at the same time.

[0007] In any embodiment of the present application, the total pore volume V of the carbon material is 2.3×10 -3 ~7.5×10-3 cm 3 / g, preferably 2.4×10 -3 ~6.0×10 -3 cm 3 When the total pore volume of the carbon material is within the above range, the secondary battery can better achieve high initial coulombic efficiency, high energy density, and good cycle performance and storage performance all at the same time.

[0008] In any embodiment of the present application, the powder compressed density P of the carbon material at a pressure of 50,000 N is 1.80 to 2.10 g / cm 3 and preferably 1.82 to 2.06 g / cm 3 When the powder compressed density of the carbon material at a pressure of 50,000 N is within the above range, the compressed density of the electrode sheet using the carbon material is high, which contributes to improving the packing ratio and energy density of the secondary battery, and the electrode sheet using the carbon material can have an appropriate pore structure, which contributes to the infiltration of the electrolyte and further improves the transport performance of active ions, thereby improving the cycle performance and / or kinetic performance of the secondary battery.

[0009] In any embodiment of the present application, the carbon material has a pore area of 0.1 μm 2 and preferably has a pore area of 0.12 to 1.5 μm 2 When the carbon material further comprises a pore structure having the above pore area, the pore structure can ensure an expansion space required for volume changes of the carbon material particles, thereby reducing the risk of new interface formation due to damage to the carbon material particles, and further reducing the occurrence of side reactions, reducing irreversible capacity loss of the secondary battery, and improving the cycle performance and storage performance of the secondary battery.

[0010] In any embodiment of the present application, the carbon material includes an outer region and an inner region located inside the outer region, the outer region refers to a region extending from the particle surface of the carbon material to the particle interior by a distance of 0.25L, where L refers to the minor axis length of the carbon material particle, the total pore area of the outer region is denoted as S1, the total pore area of the inner region is denoted as S2, and S2 > S1. When the carbon material further satisfies S2 > S1, it can effectively reduce irreversible capacity loss of a secondary battery, improve the capacity development characteristics of the secondary battery, and achieve high initial coulombic efficiency, high energy density, and good cycle performance and storage performance for the secondary battery.

[0011] In any embodiment of the present application, 1.5≦S2 / S1≦460, preferably 1.7≦S2 / S1≦380. When the S2 / S1 of the carbon material further satisfies the above range, the secondary battery can better achieve a high initial coulombic efficiency, a high energy density, and good cycle performance and storage performance all at the same time.

[0012] In any embodiment of the present application, 0.01 μm 2 ≦S1≦15.0μm 2 and preferably 0.02 μm 2 ≦S1≦12.0μm 2 When the total pore area of the outer region of the carbon material is within the above range, the carbon material particles can be provided with a more stable structure, and the infiltration of the electrolyte into the pore structure inside the carbon material particles can be prevented as much as possible, thereby reducing the occurrence of side reactions and the consumption of active ions due to the formation of an SEI film inside the particles, without affecting the transport performance of active ions and electrons.

[0013] In any embodiment of the present application, 2.5 μm 2 ≦S2≦25.0μm 2 and preferably 3.0 μm 2 ≦S2≦22.5μm 2When the total pore area of the internal region of the carbon material is within the above range, a sufficient and stable expansion space can be secured for the volume change of the carbon material particles, reducing the risk of new interface formation due to damage to the carbon material particles, reducing the occurrence of side reactions on the new interface surface, and reducing the consumption of active ions due to the formation of an SEI film on the new interface surface, while also improving the capacity and initial coulombic efficiency of the carbon material.

[0014] In any embodiment of the present application, L≧4 μm, preferably 6 μm≦L≦18 μm.

[0015] In any embodiment of the present application, the area of the pore structure in the outer region of the carbon material is 0.13 μm 2 less than or equal to 0.1 μm, preferably 2 By controlling the area size of the pore structure in the outer region of the carbon material to be within the above range, it is possible to provide a dense structure in the outer region of the carbon material. This effectively improves the structural stability of the carbon material, prevents the electrolyte from penetrating the pore structure inside the particles of the carbon material as much as possible, and further improves the cycle performance and storage performance of the secondary battery.

[0016] In any embodiment of the present application, the inner region of the carbon material has an area of 0.1 μm 2 and preferably has an area of 0.12 to 2.0 μm 2 By including a pore structure of the above size in the internal region of the carbon material, a stable expansion space sufficient for volume changes of the carbon material particles can be secured, reducing the risk of new interface formation due to breakage of the carbon material particles, while also improving the compressed density of the carbon material.

[0017] In any embodiment of the present application, the layer spacing of the outer region of the carbon material is denoted as d1 and the layer spacing of the inner region of the carbon material is denoted as d2, where d1≧d2, and preferably d1>d2, is satisfied. The larger layer spacing of the outer region of the carbon material further contributes to the rapid insertion and extraction of active ions, thereby further improving the dynamic performance of the secondary battery, and the smaller layer spacing of the inner region of the carbon material contributes to the improvement of the gram capacity and compressed density of the carbon material, thereby further improving the energy density of the secondary battery.

[0018] In any embodiment of the present application, d1 is 0.33565 to 0.33600 nm.

[0019] In any embodiment of the present application, d2 is 0.33553 to 0.33575 nm.

[0020] In any embodiment of the present application, the specific surface area of the carbon material is 0.6 to 2.0 m 2 / g, preferably 0.8 to 1.6m 2 The carbon material of the present invention has a relatively low specific surface area and a relatively low surface activity, which reduces the consumption of active ions due to the formation of the SEI film and improves the initial Coulomb efficiency of the carbon material.

[0021] In any embodiment of the present application, the volume distribution particle size Dv50 of the carbon material is 8.0 to 20.0 μm, and preferably 8.5 to 19.0 μm.

[0022] In any embodiment of the present application, the volume distribution particle size Dv10 of the carbon material is 5.0 to 15.0 μm, and preferably 6.0 to 14.0 μm.

[0023] In any embodiment of the present application, the volume distribution particle diameter Dv90 of the carbon material is 16.0 to 35.0 μm, and preferably 17.0 to 34.0 μm.

[0024] When the volume distribution particle diameters Dv10, Dv50, and / or Dv90 of the carbon material are within the above ranges, they contribute to the transport performance of active ions and electrons and also contribute to the formation of an optimal pore structure between particles in the negative electrode membrane layer, thereby further improving the cycle performance and / or power consumption performance of the secondary battery.

[0025] In any embodiment of the present application, the (Dv90-Dv10) / Dv50 of the carbon material is 0.5 to 1.5, preferably 0.7 to 1.45. When the (Dv90-Dv10) / Dv50 of the carbon material is in the above range, the particle packing characteristics are excellent, which contributes to improving the compressed density of the negative electrode film layer, thereby further improving the energy density of the secondary battery, and also contributes to forming an optimal pore structure between the particles of the negative electrode film layer.

[0026] In any embodiment of the present application, the carbon material may have one or more of a block-like, spherical, or quasi-spherical appearance, which contributes to improving the compression density of the negative electrode sheet and further improves the energy density of the secondary battery.

[0027] In any embodiment of the present application, the graphitization degree of the carbon material is 94.0% to 98.5%, preferably 94.5% to 98.0%. When the graphitization degree of the carbon material is in the above range, it contributes to improving the transport performance of active ions and electrons of the negative electrode film layer, contributing to the carbon material having a high gram capacity, and further contributing to improving the cycle performance, storage performance, and / or power consumption performance of the secondary battery.

[0028] In any embodiment of the present application, the tap density of the carbon material is 0.80 to 1.30 g / cm 3 and preferably 0.85 to 1.28 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 improved, and the energy density of the secondary battery can be further improved. This also contributes to the formation of an optimal pore structure between particles in the negative electrode film layer, improving the transport performance of active ions and electrons, and improving the cycle performance and storage performance of the secondary battery.

[0029] In any embodiment of the present application, the gram capacity of the carbon material is 350 to 371 mAh / g, and preferably 353 to 370 mAh / g. When the gram capacity of the carbon material is in the above range, the energy density of the secondary battery can be improved.

[0030] A second aspect of the present application is a method for producing a carbon material, the method comprising: Step 1 providing a raw material having a plurality of pore structures; Step 2 uniformly mixing the raw material and a filler material in a predetermined ratio, and then maintaining the temperature at a first temperature T1 for a first time t1 to obtain an intermediate; and Step 3 maintaining the temperature of the obtained intermediate at a second temperature T2 for a second time t2 to obtain a carbon material, the carbon material having a pore structure, wherein the total pore volume of the carbon material is denoted as V and the powder compressed density of the carbon material at a pressure of 50,000 N is denoted as P, and the carbon material has a pore volume of 4.1 × 10 -3 ≦V×P≦12.0×10 -3 and the total pore volume V of the carbon material is expressed in cm 3 / g, and the powder compressed density P of the carbon material at a pressure of 50,000 N is in g / cm 3 The present invention provides a method for producing a carbon material comprising the steps of:

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

[0032] In any embodiment of the present application, the volume distribution particle size Dv50 of the raw material is 9.0 to 20.0 μm, and preferably 10.0 to 19.0 μm.

[0033] In any embodiment of the present application, the total pore volume of the raw material is ≥ 10 x 10 -3 cm 3 / g, preferably 20×10 -3 ~60×10 -3 cm 3 When the pore volume of the raw material is in the above range, it contributes to the subsequent filling treatment and also contributes to the carbon material having a high gram capacity.

[0034] In any embodiment of the present application, the graphitization degree of the raw material is ≧94.0%, which contributes to the produced carbon material having a high capacity and / or a high pressed density, and further contributes to the improvement of the energy density of the secondary battery.

[0035] In any embodiment of the present application, the softening point temperature of the filler material is 95 to 158° C., preferably 100 to 145° C. When the softening point temperature of the filler material is within the above range, it contributes to the carbon material having an appropriate total pore volume, and also contributes to adjusting the pore size and / or the number of pores in the outer region and inner region of the carbon material to be within an appropriate range.

[0036] In any embodiment of the present application, the coking value of the packing material is 15% to 42%, preferably 20% to 38%, which contributes to the carbon material having an appropriate total pore volume and also contributes to adjusting the pore size and / or pore number in the outer and inner regions of the carbon material to be within an appropriate range.

[0037] In any embodiment of the present application, the volume distribution particle size Dv50 of the filler material is 6 μm or less, preferably 1 to 5 μm, which contributes to the filler material being heated and melted and then being filled into the pore structure of the raw material, and also contributes to the uniform dispersion of the filler material and the raw material.

[0038] In any embodiment of the present application, the filler material comprises one or more of coal asphalt and petroleum asphalt.

[0039] In any embodiment of the present application, the mass ratio of the filler material to the raw material is (10-30):100, preferably (11-20):100. This contributes to the carbon material having an appropriate total pore volume, and also contributes to adjusting the size and / or number of pores in the outer and inner regions of the carbon material to fall within an appropriate range.

[0040] In any embodiment of the present application, after the raw material and the filling material are uniformly mixed in a predetermined proportion, the temperature-raising process for raising the temperature to the first temperature T1 is a stepwise temperature-raising process, preferably including a first temperature-raising process and a second temperature-raising process.

[0041] In any embodiment of the present application, in the first temperature-raising process, the temperature is raised to 200 to 250° C. and kept at that temperature for 1 to 3 hours.

[0042] In any embodiment of the present application, the second temperature-raising process involves raising the temperature to the first temperature T1 and maintaining the temperature for a first time t1.

[0043] In any embodiment of the present application, the temperature is raised to the first temperature T1 at a rate of 1 to 10°C / min, preferably 2 to 8°C / min.

[0044] In any embodiment of the present application, the first temperature T1 is 700 to 1200°C, and preferably 800 to 1100°C.

[0045] In any embodiment of the present application, the first time period t1 is 1 to 5 hours, and preferably 2 to 4 hours.

[0046] Adjusting one or more of the heating rate, first temperature, first time, heating process, etc. to fall within the above ranges contributes to the production and acquisition of a carbon material with a desired pore structure, for example, contributing to the carbon material having an appropriate total pore volume, and also contributing to adjusting the pore size and / or number of pores in the outer and inner regions of the carbon material to fall within an appropriate range.

[0047] In any embodiment of the present application, the second temperature T2 is 1950 to 2550°C, and preferably 2050 to 2500°C.

[0048] In any embodiment of the present application, the second time t2 is 1.5 to 6 hours, preferably 2 to 5 hours. A third aspect of the present application provides a secondary battery including a negative electrode sheet comprising the carbon material of the first aspect of the present application or the carbon material produced by the method of the second aspect of the present application.

[0049] Adjusting one or more of the second temperature and the second time to be within the above ranges contributes to the carbon material having a high gram capacity and / or a high pressed density, and also contributes to the carbon material having an appropriate total pore volume.

[0050] In a fourth aspect of the present application, there is provided a power consumption device including the secondary battery of the third aspect of the present application.

[0051] The power consumption device of the present application includes the secondary battery provided in the present application, and therefore has at least the same advantages as the secondary battery. [Brief explanation of the drawings]

[0052] In order to more clearly explain the technical solutions of the embodiments of the present application, the drawings required in the embodiments of the present application are briefly described below. Obviously, the drawings described below are merely some embodiments of the present application, and those skilled in the art can obtain other drawings based on the drawings without the need for creative work. [Figure 1] FIG. 1 is a schematic diagram of a cross-sectional image of one of the particles of the carbon material of the present application. [Figure 2] FIG. 2 is a schematic diagram of one embodiment of the secondary battery of the present application. [Figure 3] FIG. 3 is an exploded schematic view of one embodiment of the secondary battery of the present application. [Figure 4] FIG. 4 is a schematic diagram of one embodiment of the battery module of the present application. [Figure 5] FIG. 5 is a schematic diagram of one embodiment of the battery pack of the present application. [Figure 6] FIG. 6 is an exploded schematic view of the embodiment of the battery pack shown in FIG. [Figure 7]FIG. 7 is a schematic diagram of one embodiment that includes a secondary battery of the present application as a power consumer of a power source. [Explanation of symbols]

[0053] In the drawings, the drawings are not necessarily drawn to scale. 1 battery pack 2 Upper housing 3 Lower housing 4 Battery Module 5 Secondary battery 51 Housing 52 Electrode Assembly 53 Cover plate 100 Carbon Materials 101 External area 102 Internal area DETAILED DESCRIPTION OF THE INVENTION

[0054] Hereinafter, with appropriate reference to the drawings, embodiments of the present application will be described in detail, including the carbon material, its manufacturing method, and secondary batteries and power consumption devices containing the carbon material. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters and redundant description of substantially identical structures may be omitted. This is to avoid unnecessary redundancy in the following description and to make it easier for those skilled in the art to understand. Furthermore, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0055] The "ranges" disclosed herein are defined by lower and upper limits, and a given range is defined by selecting the lower and upper limits, with the selected lower and upper limits defining the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of their endpoints and may be arbitrarily combined, i.e., any lower limit and any upper limit may be combined to form a range. For example, if ranges of 60 to 120 and 80 to 110 are recited for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if minimum range values of 1 and 2 are recited and maximum range values of 3, 4, and 5 are recited, ranges of 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, 2 to 5, etc. are all contemplated. In this application, unless otherwise specified, a numerical range "a to b" is shorthand for any combination of real numbers from a to b, where a and b are real numbers. For example, the numerical range "0 to 5" indicates that all real numbers between "0 and 5" are listed herein, with "0 to 5" being shorthand for combinations of these numbers. Furthermore, when a parameter is expressed as an integer ≧2, this is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0056] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, and such technical solutions are deemed to be included in the disclosure content of the present application.

[0057] Unless otherwise specified, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions, and such technical solutions are deemed to be included in the disclosure content of the present application.

[0058] Unless otherwise specified, all steps in this application can be performed in order or randomly, preferably in order. For example, when a method includes step (a) and step (b), this means that the method may include steps (a) and (b) performed in order, or may include steps (b) and (a) performed in order. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b), etc.

[0059] Unless otherwise specified, the terms "comprises" and "comprises" used herein have both open-ended and closed-ended meanings. For example, "comprises" and "comprises" may mean that other components not listed may be included or may comprise, or may include or comprise only the listed components.

[0060] Unless otherwise specified, the term "or" in this application has an inclusive meaning. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any one of the following conditions satisfies "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).

[0061] Unless otherwise specified, terms used in this application have the known meanings commonly understood by those of ordinary skill in the art.

[0062] Unless otherwise specified, the numerical values of each parameter mentioned in this application can be measured by various test methods commonly used in the field, for example, according to the test methods described in this application.

[0063] Unless otherwise specified, in this application, the term "active ions" refers to ions that can be inserted or extracted between the positive electrode and the negative electrode of a secondary battery, including, but not limited to, lithium ions.

[0064] As used herein, the terms "plurality" and "multiple types" mean two or more than two types.

[0065] According to the manufacturing process or origin, graphite can be divided into artificial graphite and natural graphite. The manufacturing of artificial graphite generally requires a high-temperature graphitization process, which consumes a lot of energy and is expensive, which leads to high costs for the artificial graphite. Natural graphite, which is derived from nature, has the advantage of being relatively low cost. Another advantage of natural graphite is that it has a high capacity.

[0066] Natural graphite mainly includes flake graphite, natural spherical graphite, and microcrystalline graphite. Unlike conventional artificial graphite, natural graphite has numerous pores and defects inside and outside the particles. During the initial charge process of a secondary battery, numerous side reactions occur between the electrolyte and the particle surface and the pores inside the particles, resulting in a large initial irreversible capacity loss, a low initial coulombic efficiency, and poor cycle and storage performance. In particular, flake graphite and natural spherical graphite have high crystallinity and a high degree of graphitization, and their microscopic structure is primarily layered. Due to this structure, natural graphite experiences large volume changes during the process of active ion escape and insertion, which easily leads to damage to the graphite layer structure and particle breakage. After particle breakage, the exposed fresh surface continues to react with the electrolyte, further increasing the irreversible capacity loss of the secondary battery.

[0067] Currently, in order to improve the performance of natural graphite, particle surface coating treatment and / or particle internal filling treatment are mainly carried out.

[0068] Particle surface coating treatment involves uniformly mixing natural graphite with a coating agent (e.g., asphalt, a polymer compound, etc.) and then heat treating the mixture to coat the surface of the natural graphite particles with a carbon layer and repair minor defects on the particle surface. However, the inventors of the present invention discovered during their research that the amorphous carbon layer on the surface reduces the gram capacity and / or compressed density of the natural graphite, affecting the energy density of the secondary battery. Furthermore, the amorphous carbon layer on the surface cannot effectively prevent the electrolyte from penetrating the pore structure inside the particles, thereby limiting the effects of improving the initial coulombic efficiency, cycle performance, and / or storage performance of the secondary battery.

[0069] The particle interior filling process is mainly performed by mixing natural graphite with a filler (e.g., asphalt, a polymer compound, etc.), presetting the pressure, raising the temperature, etc., to fill the filler into the pores inside the particles so as to obtain natural graphite without pores inside the particles. However, the inventors of the present application discovered during their research that a large amount of carbon, especially soft carbon, filled inside the particles reduces the gram capacity of natural graphite, affecting the energy density of secondary batteries. At the same time, because the pores inside the natural graphite particles are all filled with carbon, natural graphite experiences large volume changes during the process of active ion escape and insertion, making the particles more susceptible to breakage. As a result, the SEI film on the particle surface is easily repeatedly destroyed and reconstructed, further increasing the irreversible consumption of active ions, increasing the irreversible capacity loss of secondary batteries, and shortening the service life of secondary batteries.

[0070] Therefore, after natural graphite is modified by the particle surface coating treatment and / or particle interior filling treatment, the irreversible capacity loss of the secondary battery can be reduced to some extent and the initial coulombic efficiency of the secondary battery can be increased, but the improvement effect on the initial coulombic efficiency of the secondary battery is limited, and the energy density of the secondary battery is also lost. In addition, the capacity performance characteristics of the secondary battery during long cycles and storage are still poor.

[0071] In view of this, the inventors of the present application have conducted extensive research and have proposed a new carbon material that combines high gram capacity, high initial coulombic efficiency, and small volume change, and can provide secondary batteries with high initial coulombic efficiency, high energy density, and good cycle performance and storage performance.

[0072] carbon materials

[0073] In a first aspect of the present embodiment, a carbon material is provided.

[0074] The carbon material has a pore structure. The total pore volume of the carbon material is denoted as V, and the powder compaction density of the carbon material at a pressure of 50,000 N is denoted as P. The carbon material has a pore structure of 4.1×10 -3 ≦V×P≦12.0×10 -3 and the total pore volume V of the carbon material is expressed in cm 3 / g, and the powder compressed density P of the carbon material at a pressure of 50,000 N is in g / cm 3 is.

[0075] The inventor of the present application discovered that the carbon material was 4.1 × 10 -3 ≦V×P≦12.0×10 ―3The inventors have found that when the above requirements are met, the secondary battery can achieve a high initial coulombic efficiency, a high energy density, and good cycle and storage performance. According to the inventors' research, in this case, the carbon material can have an appropriate structure, with few pores in the carbon material particles, but at the same time, some pores with a relatively large pore area are reserved. This pore structure with a relatively large pore area can provide the expansion space required for volume changes in the carbon material particles, thereby reducing the risk of new interface formation due to damage to the carbon material particles, further reducing the occurrence of side reactions, reducing irreversible capacity loss in the secondary battery, and improving the cycle and storage performance of the secondary battery. The small pore structure in the particles allows the carbon material particles to have a stable structure, minimizing the intrusion of the electrolyte into the pore structure inside the carbon material particles, thereby reducing the occurrence of side reactions, reducing the consumption of active ions due to the formation of an SEI film inside the particles, and further improving the initial coulombic efficiency of the carbon material, thereby further improving the cycle and storage performance of the secondary battery. Therefore, the carbon material provided in the present application can effectively reduce the irreversible capacity loss of a secondary battery, improve the capacity development characteristics of the secondary battery, and enable the secondary battery to achieve both high initial coulombic efficiency, high energy density, and good cycle performance and storage performance.

[0076] V×P is 4.1×10 ―3 If the total pore volume of the carbon material is smaller than this, the total pore volume of the carbon material may be relatively small, and / or the powder compaction density of the carbon material at a pressure of 50,000 N may be small. If the total pore volume of the carbon material is small, the volume change of the carbon material particles during the process of active ion escape and insertion will be large, making the particles more susceptible to damage, and the SEI film on the particle surface will be easily destroyed and reconstructed repeatedly, thereby 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. If the powder compaction density of the carbon material at a pressure of 50,000 N is low, the carbon material may contain a high content of soft carbon, thereby reducing the gram capacity of the carbon material and affecting the energy density of the secondary battery.

[0077] V×P is 12.0×10 -3 When the total pore volume of the carbon material is larger than 50000 N, the total pore volume of the carbon material may be relatively large, and / or the powder compaction density of the carbon material at a pressure of 50000 N may be large. When the total pore volume of the carbon material is large, there will be more defects on the particle surface and inside the carbon material, and more side reactions will occur between the electrolyte and the particle surface and the pores inside the particles, resulting in a large initial irreversible capacity loss of the secondary battery, a low initial coulombic efficiency, and poor cycle performance and storage performance. Since the powder compaction density of the carbon material at a pressure of 50000 N can reflect the actual compaction state of the electrode sheet to be produced, when the powder compaction density of the carbon material at a pressure of 50000 N is large, there will be fewer voids between the carbon material particles in the electrode sheet, which will result in poor electrolyte infiltration into the electrode sheet and be unfavorable to the escape and insertion of active ions, resulting in poor cycle performance and / or kinetic performance of the secondary battery.

[0078] In some embodiments, the carbon material further comprises 4.2×10 ―3 ≦V×P≦11.0×10 ―3 , 4.3 × 10 ―3 ≦V×P≦10.0×10 ―3 , 4.4×10 ―3 ≦V×P≦8.0×10 ―3 , 4.4×10 ―3 ≦V×P≦7.0×10 ―3 , 4.4×10 ―3 ≦V×P≦6.5×10 ―3 In further research, the inventors have found that when the V×P of the carbon material is in the above range, the secondary battery can better achieve a high initial coulombic efficiency, a high energy density, and good cycle performance and storage performance all at the same time.

[0079] In some embodiments, the total pore volume V of the carbon material is 2.3 × 10 to 7.5 × 10 ―3 cm 3 / g, preferably 2.35×10 ―3 ~6.0×10 ―3 cm 3 / g, 2.37 × 10 ―3~6.0×10 ―3 cm 3 / g, 2.4 × 10 ―3 ~6.0×10 ―3 cm 3 / g, 2.4 × 10 ―3 ~5.5×10 ―3 cm 3 / g, 2.4 × 10 ―3 ~5.0×10 ―3 cm 3 / g, 2.4 × 10 ―3 ~4.5×10 ―3 cm 3 / g, 2.4 × 10 ―3 ~4.0×10 ―3 cm 3 / g. When the total pore volume of the carbon material is within the above range, the risk of new interface formation due to damage to the carbon material particles is reduced, and the occurrence of side reactions is also reduced, contributing to reducing irreversible capacity loss in secondary batteries. It also contributes to providing the carbon material particles with a more stable structure, and by preventing the electrolyte from penetrating the pore structure inside the carbon material particles as much as possible, the occurrence of side reactions is reduced and the consumption of active ions due to the formation of an SEI film inside the particles is reduced. Therefore, when the total pore volume of the carbon material is within the above range, secondary batteries can be made to have a high initial coulombic efficiency, a high energy density, and good cycle performance and storage performance all at the same time.

[0080] In some embodiments, the powder compaction density P of the carbon material at a pressure of 50,000 N is 1.80 to 2.10 g / cm 3 and preferably 1.82 to 2.06 g / cm 3 , 1.82~2.00g / cm 3 , 1.85~1.96g / cm 3 , 1.85~1.94g / cm 3 , 1.85~1.92g / cm 3When the powder compressed density of the carbon material at a pressure of 50,000 N is within the above range, the compressed density of the electrode sheet using the carbon material is high, which contributes to improving the packing ratio and energy density of the secondary battery, and the electrode sheet using the carbon material can have an appropriate pore structure, which contributes to the infiltration of the electrolyte and further improves the transport performance of active ions, thereby improving the cycle performance and / or kinetic performance of the secondary battery.

[0081] The total pore volume of a carbon material has a meaning known in the art and can be measured using devices and methods known in the art. An exemplary test method is as follows: A certain mass of carbon material sample (e.g., 1.5 to 3.5 g) is placed in a sample tube, dried, and degassed at 200°C for 2 hours. It is then placed in a Tristar II 3020 instrumental analysis station for testing to obtain the total pore volume of the carbon material. During testing, the adsorption gas may be nitrogen, and the adsorption temperature may be 77 K (K represents the temperature in Kelvin).

[0082] The powder compaction density of a carbon material has a meaning known in the art and can be measured using an apparatus and method known in the art. For example, it can be measured with an electronic pressure tester (e.g., UTM7305 type electronic pressure tester) in accordance with GB / T24533-2009. An exemplary test method is as follows: 1 g of carbon material powder is weighed out and measured to determine whether it has a base area of 1.327 cm. 2 The powder is placed in a mold, pressurized to 5000 kg (equivalent to 50,000 N), and held for 30 seconds. The pressure is then released and held for 10 seconds, after which the powder is recorded and calculated to obtain the powder compression density of the carbon material at a pressure of 50,000 N.

[0083] In some embodiments, the carbon material has a pore area of 0.1 μm 2 and preferably has a pore area of 0.12 to 1.5 μm 2When the carbon material further comprises a pore structure having the above pore area, the pore structure can ensure an expansion space required for volume changes of the carbon material particles, thereby further reducing the risk of new interface formation due to damage to the carbon material particles, further reducing the occurrence of side reactions, reducing irreversible capacity loss of the secondary battery, and improving the cycle performance and storage performance of the secondary battery.

[0084] 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 from the particle surface of the carbon material to the interior of the particle by a distance of 0.25L, L refers to the minor axis length of the carbon material particle, the total pore area of the outer region is denoted as S1, the total pore area of the inner region is denoted as S2, and S2 > S1.

[0085] In the present application, the total pore area S1 of the outer region and the total pore area S2 of the inner region of the first carbon-based material can be tested and obtained by a cross-sectional image of the first carbon-based material.

[0086] In this application, a cross-sectional image of a first carbon-based material includes a cross-sectional image through a particle center of the first carbon-based material, where "particle center" means an area extending from the geometric center of the particle to the particle surface by a radius of 0.1 μm.

[0087] In the present application, the minor axis length of a particle means the minimum value when a line connecting two points on the particle surface passes through the geometric center of the particle.

[0088] 1 is a schematic diagram of a cross-sectional image of one particle of the carbon material 100 of the present application, and the cross-sectional image passes through the center of the particle of the carbon material 100. As shown in FIG. 1, L represents the minor axis length of the particle of the carbon material 100, and the region extending from the particle surface of the carbon material 100 to the interior of the particle by a distance of 0.25L is the outer region 101, and the region inside the outer region 101 is the inner region 102.

[0089] A cross section of the first carbon-based material is prepared using a cross section polishing device (e.g., an IB-09010CP argon ion cross section polishing device manufactured by JEOL Corporation, Japan), and then, referring to JY / T010-1996, a scanning electron microscope (e.g., a Sigma300 scanning electron microscope manufactured by ZEISS Corporation, Germany) is used to scan the cross section of the first carbon-based material, and finally, the total pore area S1 of the outer region and the total pore area S2 of the inner region of the first carbon-based material can be calculated using image processing software (e.g., AVIZO).

[0090] When the carbon material further satisfies S2>S1, the carbon material particles are characterized by a large number of pores and / or large pore size in the inner region, and a small number of pores and / or small pore size in the outer region. The large number of pores and / or large pore size in the inner region of the carbon material ensures expansion space necessary for volume changes in the carbon material particles, thereby reducing the risk of new interface formation due to damage to the carbon material particles, further reducing the occurrence of side reactions, reducing irreversible capacity loss in secondary batteries, and improving the cycle performance and storage performance of secondary batteries. The small number of pores and / or small pore size in the outer region provides the carbon material particles with a more stable structure, minimizing the intrusion of the electrolyte into the pore structure inside the carbon material particles, thereby reducing the occurrence of side reactions, reducing the consumption of active ions due to the formation of an SEI film inside the particles, and further improving the initial Coulombic efficiency of the carbon material, further improving the cycle performance and storage performance of secondary batteries. Therefore, when the carbon material further satisfies S2>S1, it can effectively reduce the irreversible capacity loss of the secondary battery, improve the capacity performance of the secondary battery, and provide the secondary battery with high initial coulombic efficiency, high energy density, and good cycle performance and storage performance.

[0091] In some embodiments, 1.5≦S2 / S1≦460, 1.7≦S2 / S1≦380, 2≦S2 / S1≦350, 2.1≦S2 / S1≦300, 2.2≦S2 / S1≦200, 2.2≦S2 / S1≦150. In further studies, the inventors have found that when the S2 / S1 of the carbon material is further within the above range, the secondary battery can better achieve a high initial coulombic efficiency, a high energy density, and good cycle performance and storage performance all at the same time.

[0092] In some embodiments, 0.01 μm 2 ≦S1≦15.0μm 2 and preferably 0.02 μm 2 ≦S1≦12.0μm 2 , 0.1 μm 2 ≦S1≦12.0μm 2 , 0.2 μm 2 ≦S1≦12.0μm 2 , 0.2 μm 2 ≦S1≦10.0μm 2 When the total pore area of the outer region of the carbon material is within the above range, the carbon material particles can be provided with a more stable structure, and the infiltration of the electrolyte into the pore structure inside the carbon material particles can be prevented as much as possible, thereby reducing the occurrence of side reactions and the consumption of active ions due to the formation of an SEI film inside the carbon material particles, without affecting the transport performance of active ions and electrons.

[0093] In some embodiments, 2.5 μm 2 ≦S2≦25.0μm 2 and preferably 3.0 μm 2 ≦S2≦22.5μm 2 , 3.5 μm 2 ≦S2≦20.0μm 2 , 4.0 μm 2 ≦S2≦17.5μm 2When the total pore area of the internal region of the carbon material is within the above range, a sufficient and stable expansion space can be secured for the volume change of the carbon material particles, reducing the risk of new interface formation due to damage to the carbon material particles, reducing the occurrence of side reactions on the new interface surface, and reducing the consumption of active ions due to the formation of an SEI film on the new interface surface, while also improving the capacity and initial coulombic efficiency of the carbon material.

[0094] In some embodiments, L≧4 μm, preferably 4 μm≦L≦20 μm, 6 μm≦L≦19 μm, 8 μm≦L≦19 μm, 8 μm≦L≦18 μm, 8 μm≦L≦16 μm.

[0095] In some embodiments, the area of the pore structure in the outer region of the carbon material is less than 0.13 μm 2 less than or equal to 0.1 μm, preferably 2 The inventors have further discovered through further research that by controlling the area size of the pore structure in the outer region of the carbon material to be within the above range, it is possible to provide a dense structure in the outer region of the carbon material, thereby effectively improving the structural stability of the carbon material, preventing the electrolyte from penetrating into the pore structure inside the particles of the carbon material as much as possible, and further improving the cycle performance and storage performance of the secondary battery. Of course, in the present application, it is assumed that the area of all pore structures in the outer region of the carbon material is 0.13 μm 2 There is no intention to limit the area to 0.13 μm or less, and for example, it may be controlled to 95% or more, and preferably 99% or more of the area of the pore structure is 0.13 μm 2 less than or equal to 0.1 μm, preferably 2 The following is the result.

[0096] In some embodiments, the interior region of the carbon material has an area of 0.1 μm 2 and preferably has an area of 0.12 to 2.0 μm 2In further research, the inventors have discovered that by including a pore structure of the above size in the internal region of the carbon material, a stable expansion space sufficient for volume changes of the carbon material particles can be secured, reducing the risk of new interface formation due to breakage of the carbon material particles, while also improving the compressed density of the carbon material.

[0097] In some examples, in any embodiment of the present application, when the layer spacing of the outer region of the carbon material is denoted as d1 and the layer spacing of the inner region of the carbon material is denoted as d2, the carbon material satisfies d1≧d2, and preferably d1>d2.

[0098] The relatively large interlayer spacing in the outer region of the carbon material further contributes to the rapid insertion and extraction of active ions, thereby further improving the dynamic performance of the secondary battery, and the relatively small interlayer spacing in the inner region of the carbon material contributes to the improvement of the gram capacity and compressed density of the carbon material, thereby further improving the energy density of the secondary battery.

[0099] In some embodiments, d1 is between 0.33565 and 0.33600 nm.

[0100] In some embodiments, d2 is between 0.33553 and 0.33575 nm.

[0101] The layer spacing of different regions of the carbon material particles can be tested using equipment and methods known in the art. For example, a High Resolution Transmission Electron Microscope (HRTEM) may be used. A Thermo Fisher Scientific Spectra S / TEM scanning transmission electron microscope may be used as the testing equipment.

[0102] In some embodiments, the carbon material contains primary particles. Preferably, the proportion of the primary particles in the carbon material is ≧50%, for example, 55% to 95%, 60% to 100%, 65% to 90%, 65% to 80%, 70% to 100%, 75% to 90%, 80% to 100%, 90% to 100%, or 95% to 100%. When the carbon material contains primary particles in an appropriate proportion, it can provide high structural stability and reduce the occurrence of side reactions. It can also improve the compression density of the negative electrode sheet and improve the energy density of the secondary battery.

[0103] In some embodiments, the carbon material may be all primary particles, ie, the proportion of the primary particles in the carbon material is 100% by number.

[0104] Primary particles and secondary particles have the meanings known in the art. Primary particles refer to particles in a non-agglomerated state. Secondary particles refer to particles in an agglomerated state formed by the aggregation of two or more primary particles. Primary particles and secondary particles may be distinguished using scanning electron microscope (SEM) images.

[0105] In this application, the quantitative proportion of primary particles in a carbon material can be tested according to the following method: a test sample is randomly taken from the negative electrode film layer, multiple test areas are randomly taken from the test sample, images of the multiple test areas are obtained using a scanning electron microscope, the proportion of the number of carbon material particles with primary particle appearance in each image to the total number of carbon material particles is calculated, and the average value of the multiple statistical results is the quantitative proportion of primary particles in the carbon material.

[0106] In some embodiments, the carbon material has an appearance that includes one or more of a block shape, a spherical shape, and a quasi-spherical shape, which contributes to improving the compression density of the negative electrode sheet and further improves the energy density of the secondary battery.

[0107] In some embodiments, the graphitization degree of the carbon material is 94.0% to 98.5%, preferably 94.5% to 98.0%, which contributes to improving the transport performance of active ions and electrons in the negative electrode film layer, contributing to the carbon material having a high gram capacity, and further contributing to improving the cycle performance, storage performance, and / or power consumption performance of the secondary battery.

[0108] The graphitization degree of a carbon material has a meaning known in the art and can be tested using an apparatus and method known in the art. For example, the test can be performed using an X-ray diffractometer (e.g., Bruker D8 Discover). For the test, see JIS K0131-1996 and JB / T4220-2011. The average layer spacing d of the (002) crystal plane in the crystal structure of the carbon material can be measured. 002 Then, use the formula g=(0.344-d 002 ) / (0.344-0.3354)×100%. In the above formula, d 002 is the average layer spacing of the (002) crystal plane in the carbon material crystal structure, expressed in nanometers (nm).

[0109] In some embodiments, the specific surface area of the carbon material is 0.6 to 2.0 m 2 / g, preferably 0.8 to 1.6m 2 The carbon material of the present invention has a relatively low specific surface area and a relatively low surface activity, which reduces the consumption of active ions due to the formation of the SEI film and improves the initial Coulomb efficiency of the carbon material.

[0110] The specific surface area of the carbon material has a meaning known in the art and can be measured using an apparatus and method known in the art. For example, the specific surface area can be measured using the nitrogen adsorption specific surface area analysis test method in accordance with GB / T19587-2017 and calculated using the Brunauer Emmett Teller (BET) method. The nitrogen adsorption specific surface area analysis test can be performed using a Tri-Star 3020 specific surface area and pore size analyzer manufactured by Micromeritics, Inc., USA.

[0111] In some embodiments, the carbon material has a volume distribution particle size Dv50 of 8.0 to 20.0 μm, preferably 8.5 to 19.0 μm.

[0112] In some embodiments, the carbon material has a volume distribution particle size Dv10 of 5.0 to 15.0 μm, preferably 6.0 to 14.0 μm.

[0113] In some embodiments, the carbon material has a volume distribution particle size Dv90 of 16.0 to 35.0 μm, preferably 17.0 to 34.0 μm.

[0114] When the volume distribution particle diameters Dv10, Dv50, and / or Dv90 of the carbon material are within the above ranges, they contribute to the transport performance of active ions and electrons and also contribute to the formation of an optimal pore structure between particles in the negative electrode membrane layer, thereby further improving the cycle performance and / or power consumption performance of the secondary battery.

[0115] In some embodiments, the carbon material has a (Dv90-Dv10) / Dv50 ratio of 0.5 to 1.5, preferably 0.7 to 1.45. When the (Dv90-Dv10) / Dv50 ratio of the carbon material is within this range, the particle packing characteristics are excellent, contributing to an improvement in the compressed density of the negative electrode film layer, thereby further improving the energy density of the secondary battery. This also contributes to the formation of an optimal pore structure between the particles of the negative electrode film layer.

[0116] The volume distribution particle sizes Dv10, Dv50, and Dv90 of carbon materials have the meanings known in the art and represent the particle sizes corresponding to the cumulative volume distribution rates of the material reaching 10%, 50%, and 90%, respectively. These can be measured using devices and methods known in the art. For example, see GB / T 19077-2016 Particle Size Distribution Laser Diffraction Method, and they can be easily measured using a laser particle size analyzer. The test device can be a Malvern Panalytical Mastersizer 2000E laser particle size analyzer.

[0117] In some embodiments, the tap density of the carbon material is 0.80 to 1.30 g / cm 3 and preferably 0.85 to 1.28 g / cm 3 When the tap density of the carbon material is within the above range, the compressed density of the negative electrode sheet can be improved, and the energy density of the secondary battery can be further improved. It also contributes to the formation of an optimal pore structure between particles in the negative electrode film layer, improving the transport performance of active ions and electrons, and improving the cycle performance and storage performance of the secondary battery.

[0118] The tap density of the carbon material has a meaning known in the art and can be measured using an apparatus and method known in the art. For example, it can be measured using a powder tap density tester in accordance with GB / T 5162-2006. The test apparatus can be a Dandong Baite BT-301.

[0119] In some embodiments, the gram capacity of the carbon material is 350 to 371 mAh / g, preferably 353 to 370 mAh / g. When the gram capacity of the carbon material is in the above range, the energy density of the secondary battery can be improved.

[0120] The gram capacity of a carbon material is defined as known in the art and can be tested by methods known in the art. An exemplary test method is as follows: A sample of the carbon material is thoroughly mixed with styrene butadiene rubber (SBR) as an adhesive, sodium carboxymethyl cellulose (CMC) as a thickener, and carbon black as a conductive agent in a mass ratio of 96.2:1.8:1.2:0.8 with an appropriate amount of deionized water as a solvent to form a uniform negative electrode slurry. The negative electrode slurry is uniformly coated on the surface of a negative electrode current collector copper foil and dried in an oven before use. Ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. LiPF6 is then dissolved in the organic solvent to prepare an electrolyte solution with a concentration of 1 mol / L. Then, a CR2430-type button cell battery was assembled in an argon-protected glove box using metallic lithium flakes as the counter electrode and polyethylene (PE) film as the separator. At 25°C, the button cell was first discharged at a constant current of 0.15 mA to 0.005 V, left for 5 minutes, and then discharged at a constant current of 10 μA to 0.005 V. The first-cycle discharge capacity of the button cell was recorded. It was then charged at a constant current of 0.3 mA to 2.0 V, and the charge capacity of the button cell was recorded. The ratio of the charge capacity of the button cell to the sample mass of the carbon material is the gram capacity of the carbon material.

[0121] Manufacturing method

[0122] A second aspect of the present embodiment provides a method for producing a carbon material, which can produce the carbon material of the first aspect of the present embodiment.

[0123] The method for producing 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 material in a predetermined ratio, and then maintaining the temperature at a first temperature T1 for a first time t1 to obtain an intermediate; and Step 3 of maintaining the temperature at a second temperature T2 for a second time t2 to obtain a carbon material, wherein the carbon material has a pore structure, the total pore volume of the carbon material is denoted as V, and the powder compressed density of the carbon material at a pressure of 50,000 N is denoted as P, and the carbon material has a pore structure of 4.1 × 10 -3 ≦V×P≦12.0×10 -3 and the total pore volume V of the carbon material is expressed in cm 3 / g, and the powder compressed density P of the carbon material at a pressure of 50,000 N is in g / cm 3 is.

[0124] In some embodiments, the raw material for producing the carbon material includes natural graphite, preferably the natural graphite includes one or more of flake graphite, natural spheroidal graphite, and microcrystalline graphite, and preferably natural spheroidal graphite.

[0125] "Natural spherical graphite" refers to spherical or quasi-spherical natural graphite, and does not necessarily mean that all natural graphite particles are controlled to be ideal spheres. In some embodiments, natural spherical graphite with a desired particle size and appearance can be obtained by pre-treating flake graphite, and preferably, the pre-treatment includes steps such as breaking, classification, spheroidization, and purification.

[0126] In some embodiments, the appearance of the ingredient may include one or more of a spherical shape and a quasi-spherical shape.

[0127] In some embodiments, the volume distribution particle diameter Dv50 of the raw material may be 9.0 to 20.0 μm, and preferably 10.0 to 19.0 μm. When the volume distribution particle diameter Dv50 of the raw material is in the above range, it contributes to the subsequent filling treatment.

[0128] In some embodiments, the total pore volume of the raw material is ≥ 10 x 10 ―3 cm3 / g, preferably 20×10 ―3 cm 3 / g~60×10 ―3 cm 3 When the pore volume of the raw material is in the above range, it contributes to the subsequent filling treatment and also contributes to the carbon material having a high gram capacity.

[0129] In some embodiments, the graphitization degree of the raw material is ≧94.0%, which contributes to the produced carbon material having a high capacity and / or a high pressed density, and further contributes to improving the energy density of the secondary battery.

[0130] By adjusting the particle size and / or total pore volume of the raw material to be within the above range, it is possible to reduce aggregation of the raw material during subsequent production, thereby reducing problems such as an increase in surface defects and an increase in surface side reaction sites of the carbon material particles, which would otherwise be required to increase the number of depolymerization steps.

[0131] In some embodiments, the volume distribution particle size Dv50 of the filler material is 6 μm or less, preferably 1 to 6 μm, 1 to 5 μm, 2 to 5 μm, or 3 to 5 μm, which contributes to the filler material being filled into the pore structure of the raw material after being heated and melted, and also contributes to the uniform distribution of the filler material and the raw material.

[0132] In some embodiments, the softening point temperature of the filler material may be 95-158°C. For example, the softening point temperature of the filler material may be 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, or any range thereof. Preferably, the softening point temperature of the filler material is 100-145°C.

[0133] During the course of research, the inventors discovered that when the softening point temperature of the filler material is within the above range, it contributes to the carbon material having an appropriate total pore volume and also contributes to adjusting the pore size and / or number of pores in the outer and inner regions of the carbon material to be within an appropriate range. It also avoids the following situation: when the softening point temperature of the filler material is too high, the filler material does not easily flow and fill into the pore structure of the raw material, thereby failing to effectively reduce internal defects in the obtained carbon material particles and effectively preventing the electrolyte from penetrating into the pore structure inside the carbon material particles. The total pore volume of the obtained carbon material will be large, further affecting the initial coulombic efficiency, cycle performance, and storage performance of the secondary battery. If the softening point temperature of the filler material is too low, the filler material will contain a large amount of low molecular weight substances, which will be easily activated when heated, allowing the filler material to flow and fill into the pore structure of the raw material. However, when heat-treated at high temperatures, the low molecular weight substances in the filler material will be activated, and the actual carbon residue in the filling area will not be able to effectively fill the pore structure of the raw material, preventing effective filling. Alternatively, the actual carbon residue in the filling area will have a large pore structure, which will prevent the consumption of active ions due to the formation of an SEI film and the irreversible capacity loss of the secondary battery from being reduced, thereby affecting the cycle performance and storage performance of the secondary battery.

[0134] In some embodiments, the coking value of the filler material is 15% to 42%, preferably 18% to 38%, 20% to 38%, 22% to 38%, 24% to 38%, or 26% to 38%. The inventors have discovered in the course of their research that when the coking value of the filler material is in the above range, it contributes to the carbon material having an appropriate total pore volume and also contributes to adjusting the pore size and / or pore number in the outer and inner regions of the carbon material to be in an appropriate range.

[0135] In some embodiments, the filler material has a softening point temperature of 100°C to 145°C and a coking value of 20% to 38%.

[0136] The coking value of a carbon material has a meaning known in the art and can be measured using devices and methods known in the art, for example, by referring to GB / T8727-2008.

[0137] In some embodiments, the filler material may include one or more of coal asphalt and petroleum asphalt.

[0138] In some embodiments, the mass ratio of the filler material to the raw materials is (10-30):100, preferably (10-25):100, (10-20):100, or (11-20):100. This contributes to the carbon material having an appropriate total pore volume and also contributes to adjusting the pore size and / or number of pores in the outer and inner regions of the carbon material to within an appropriate range. It also avoids the following situation: If the mass ratio of the filler material to the raw materials is too small, the filler material will not easily flow and fill into the pore structure of the raw materials, thereby failing to effectively reduce internal defects in the obtained carbon material particles and effectively preventing the electrolyte from penetrating the pore structure inside the carbon material particles. The total pore volume of the obtained carbon material will be large, further affecting the initial coulombic efficiency, cycle performance, and storage performance of the secondary battery. If the mass ratio of the filler material to the raw materials is too large, the internal pore structure of the raw materials is likely to be completely filled, resulting in a small total pore volume of the obtained carbon material, and a large volume change in the carbon material during the process of active ion escape and insertion, making the particles more susceptible to damage, and increasing the consumption of active ions due to SEI film formation, leading to increased irreversible capacity loss of the secondary battery.Furthermore, if the mass ratio of the filler material to the raw materials is too large, most of the filler material is likely to remain on the particle surface, making the particles more likely to aggregate, not only increasing the depolymerization process but also reducing the gram capacity and / or compressed density of the obtained carbon material.

[0139] By adjusting the parameters of the filler material, such as the type, softening point, coking value, and amount added, within the above ranges, the filler material will not have a high viscosity and will maintain good fluidity after being heated and melted. At the same time, the filler material will not easily adhere to the raw material particles, reducing the aggregation of the raw material particles during the subsequent manufacturing process. This reduces the need to add a depolymerization step, thereby reducing problems such as an increase in surface defects and side reaction sites on the carbon material particles.

[0140] In some embodiments, in step 2, after the raw material and the filler material are uniformly mixed in a predetermined proportion, the temperature-raising process to raise the temperature to the first temperature T1 is a stepwise temperature-raising process, preferably including a first temperature-raising process and a second temperature-raising process.

[0141] In some embodiments, the first temperature-raising process involves raising the temperature to 200 to 250° C. and maintaining the temperature for 1 to 3 hours.

[0142] During the course of research, the inventors discovered that a warming time in the first heating process within the above range contributes to ensuring that the carbon material has an appropriate total pore volume and that the pore size and / or number in the outer and inner regions of the carbon material are adjusted to within an appropriate range. It also avoids the following situation: if the warming time in the first heating process is too short, the filler material, after being heated and melted, will not easily flow and fill into the pore structure of the raw material, which may result in carbonization on the particle surface. This will prevent effective reduction of internal defects in the obtained carbon material particles and ineffective prevention of electrolyte penetration into the pore structure inside the carbon material particles. The obtained carbon material will have a large total pore volume, which will further affect the initial coulombic efficiency, cycle performance, and storage performance of the secondary battery. If the heating time in the first heating process is too long, the filler material will easily flow and fill into all the pore structures of the raw material, and as a result, the volume of the carbon material will change significantly during the process of active ions escaping and inserting, making the particles more susceptible to damage. This will increase the consumption of active ions due to the formation of an SEI film, which will increase the irreversible capacity loss of the secondary battery and also affect the cycle performance, storage performance, and power consumption performance of the secondary battery.

[0143] In some embodiments, the second heating process involves heating to the first temperature T1 and maintaining the temperature for a first time t1.

[0144] In some embodiments, in step 2, the temperature may be increased to the first temperature T1 at a rate of 1 to 10°C / min. For example, the temperature increase rate may be 1.5°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any range of the above values. Preferably, the temperature increase rate is 1.5 to 8°C / min.

[0145] In some embodiments, the temperature rise rate of the first temperature rise process may be between 1°C / min and 10°C / min, for example, the temperature rise rate may be 1.5°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any range of the above values. Preferably, the temperature rise rate is between 1.5°C / min and 8°C / min.

[0146] The inventors discovered the following during their research: When the heating rate of the first heating process is within the above range, it contributes to ensuring that the carbon material has an appropriate total pore volume and to adjusting the pore size and / or number in the outer and inner regions of the carbon material to fall within appropriate ranges. It also avoids the following situation: If the heating rate is too high, the filler material may carbonize on the surface of the raw material particles, making it difficult for the filler material to flow and fill into the pore structure of the raw material. This prevents the internal defects of the obtained carbon material particles from being effectively reduced and the electrolyte from penetrating the pore structure inside the obtained carbon material particles from being effectively prevented. This increases the total pore volume of the obtained carbon material, further affecting the initial coulombic efficiency, cycle performance, and storage performance of the secondary battery. If the heating rate is too low, the filler material will easily flow and fill into all the pore structures of the raw material, and the carbon material will experience a large volume change during the process of active ions escaping and inserting, making the particles more susceptible to damage. This will increase the consumption of active ions due to the formation of the SEI film, increase the irreversible capacity loss of the secondary battery, and also affect the cycle performance, storage performance, and power consumption performance of the secondary battery.

[0147] In some embodiments, the temperature increase rate of the second temperature increase process may be 1 to 10°C / min, for example, 1.5°C / min, 2°C / min, 3°C / min, 4°C / min, 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, 10°C / min, or any range thereof. Preferably, the temperature increase rate is 2 to 8°C / min. This contributes to sufficient carbonization of the filler material and reduction of the volatile substance content.

[0148] During the stepwise temperature increase, the temperature is first increased to 200°C to 250°C. Because the heating temperature is higher than the softening point temperature of the filler material, the filler material is heated, melted, and softened. After maintaining the temperature for 1 to 3 hours, it flows and fills the pore structure of the raw material. The temperature is then increased to a first temperature T1, during which the melted and softened filler material undergoes a carbonization reaction, thereby effectively filling the pore structure occupied by the filler material, further contributing to the carbon material having an appropriate total pore volume and contributing to adjusting the pore size and / or pore number in the outer and inner regions of the carbon material to be within an appropriate range.

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

[0150] During the course of research, the inventors discovered the following: Setting the first temperature within the above range contributes to ensuring that the carbon material has an appropriate total pore volume and to adjusting the pore size and / or number in the outer and inner regions of the carbon material within appropriate ranges. It also avoids the following situation: If the first temperature is too low, the filler material may not be completely converted into a carbon material and may subsequently be decomposed into low-molecular-weight substances during the heat treatment in Step 3. As a result, the actual carbon residue in the filler region will have a porous structure with a large amount of carbon, which will not effectively reduce defects within the particles of the obtained carbon material, will not effectively prevent the electrolyte from penetrating into the pore structure within the particles of the carbon material, and will result in a large total pore volume of the obtained carbon material, which will further affect the initial coulombic efficiency, cycle performance, and storage performance of the secondary battery. If the first temperature is too high, the energy consumption and cost during the production of the carbon material will increase.

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

[0152] During the course of research, the inventors discovered that a first time period within the above range contributes to the carbon material having an appropriate total pore volume and also contributes to adjusting the pore size and / or pore number in the outer and inner regions of the carbon material within an appropriate range. It also avoids the following situation: If the first time period is too short, the filler material may not be completely converted into a carbon material and may subsequently be decomposed into low-molecular-weight substances during the heat treatment in Step 3. As a result, the actual carbon residue in the filler region will have a porous structure with a large amount of carbon, which will not effectively reduce the defects within the particles of the obtained carbon material, will not effectively prevent the electrolyte from penetrating the pore structure within the particles of the carbon material, and will result in a large total pore volume of the obtained carbon material, which will further affect the initial coulombic efficiency, cycle performance, and storage performance of the secondary battery. If the first time period is too long, the energy consumption and cost during the production of the carbon material will increase.

[0153] In some embodiments, in step 2, the heat treatment can be carried out in a vertical granulator, a horizontal granulator, a vertical reactor, a horizontal reactor, or a drum furnace.

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

[0155] In step 2, adjusting one or more of the heating rate, first temperature, first time, heating process, etc. to fall within the above ranges contributes to producing and obtaining a carbon material with a desired pore structure, for example, contributing to the carbon material having an appropriate total pore volume, and also contributing to adjusting the pore size and / or number of pores in the outer and inner regions of the carbon material to fall within an appropriate range.

[0156] In some embodiments, the second temperature T2 is 1950 to 2550° C. For example, the second temperature may be 2000° C., 2050° C., 2100° C., 2150° C., 2200° C., 2250° C., 2300° C., 2350° C., 2400° C., 2450° C., 2500° C., 2550° C., or any range thereof. Preferably, the second temperature T2 is 2050 to 2500° C. or 2100 to 2400° C.

[0157] The inventors discovered the following during their research: Setting the second temperature within the above range contributes to the carbon material having an appropriate total pore volume, as well as a high gram capacity and / or high pressed density. It also avoids the following situations: If the second temperature is too low, the resulting carbon material will have a high content of soft carbon, which will affect the gram capacity and / or pressed density of the carbon material; if the second temperature is too high, the resulting carbon material will have a low content of disordered carbon, resulting in a high degree of crystallinity and graphitization, which is unfavorable for the rapid escape and insertion of active ions. Furthermore, the carbon material will experience a large volume change during charging and discharging, which increases the risk of particle breakage, thereby affecting the cycle performance and / or kinetic performance of the secondary battery. Setting the second temperature too high also increases energy consumption and costs during the production of the carbon material.

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

[0159] The inventors discovered the following during their research: When the second time is within the above range, it contributes to the carbon material having an appropriate total pore volume, and also contributes to the carbon material having a high gram capacity and / or high compressed density. It also avoids the following situations: If the second time is too short, the obtained carbon material will have a high content of soft carbon, which will affect the gram capacity and / or compressed density of the carbon material; if the second time is too long, the obtained carbon material will have a low content of disordered carbon, resulting in a high degree of crystallinity and graphitization of the carbon material, which is unfavorable for the rapid escape and insertion of active ions. At the same time, the volume of the carbon material will change significantly during charging and discharging, which increases the risk of particle breakage of the carbon material and affects the cycle performance and / or kinetic performance of the secondary battery. Furthermore, if the second time is too long, it will increase energy consumption and costs during the production of the carbon material.

[0160] In some embodiments, in step 3, the heat treatment may be performed in an intermediate frequency furnace, a box graphitization furnace, an Acheson graphitization furnace, a continuous graphitization furnace, or an internal graphitization furnace.

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

[0162] Adjusting one or more of the second temperature and the second time to be within the above ranges contributes to the carbon material having a high gram capacity and / or a high pressed density, and also contributes to the carbon material having an appropriate total pore volume.

[0163] The method for producing the carbon material of the present application is simple and safe, does not require a pre-set pressure or vacuum treatment, and does not require an additional depolymerization step during heat treatment. The carbon material produced by the present application has low volume expansion, high structural stability, low surface activity, and can combine high gram capacity, high initial coulombic efficiency, and small volume change, and can be used in secondary batteries to achieve high initial coulombic efficiency, high energy density, and good cycle performance and storage performance.

[0164] The present manufacturing method is low cost, highly practical, and suitable for scalable production.

[0165] secondary battery

[0166] In a third aspect of the present embodiment, a secondary battery is provided.

[0167] The present application does not particularly limit the type of secondary battery, and for example, the secondary battery may be a lithium-ion battery or the like. Typically, a secondary battery includes a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the charge / discharge process of a secondary battery, active ions are inserted and extracted between the positive electrode sheet and the negative electrode sheet, and the electrolyte functions to transport the active ions between the positive electrode sheet and the negative electrode sheet. The present application does not particularly limit the type of electrolyte, and the electrolyte may be selected according to actual needs. For example, the electrolyte may be selected from at least one of a solid electrolyte and a liquid electrolyte (i.e., an electrolytic solution). Secondary batteries using an electrolytic solution and some secondary batteries using a solid electrolyte may include a separator, which is disposed between the positive electrode sheet and the negative electrode sheet to provide isolation.

[0168] [Negative electrode sheet]

[0169] 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 the thickness direction of the negative electrode current collector, and the negative electrode film layer is provided on one or two of the two facing surfaces of the negative electrode current collector.

[0170] In some embodiments, the negative electrode film layer comprises the carbon material of the first aspect of the present invention or the carbon material produced by the method of the second aspect of the present invention, thereby enabling the secondary battery to achieve high initial coulombic efficiency, high energy density, and good cycle and storage performance.

[0171] In some embodiments, the negative electrode film layer may further include other negative electrode active materials besides the carbon material. In some embodiments, the other negative electrode active materials may include, but are not limited to, one or more of common natural graphite, artificial graphite, soft carbon, hard carbon, silicon-based materials, tin-based materials, and lithium titanate. The silicon-based materials may include one or more of elemental silicon, silicon oxide, silicon-carbon composites, silicon-nitrogen composites, and silicon alloy materials. The tin-based materials may include one or more of elemental tin, tin oxide, and tin alloy materials.

[0172] In some embodiments, the negative electrode film layer preferably further includes a negative electrode conductive agent. The present application does not particularly limit the type of the negative electrode conductive agent, and for example, the negative electrode conductive agent may include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0173] In some embodiments, the negative electrode film layer preferably further includes a negative electrode adhesive. The present application does not particularly limit the type of the negative electrode adhesive, and for example, the negative electrode adhesive may include one or more of styrene butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, water-soluble 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).

[0174] In some embodiments, the negative electrode film layer preferably further includes other additives, such as thickeners such as sodium carboxymethyl cellulose (CMC) and PTC thermistor materials.

[0175] In some embodiments, the negative electrode current collector may be a metal foil piece or a composite current collector. An example of a metal foil piece is copper foil. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. For example, the metal material may include one or more of copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0176] The negative electrode film layer is typically formed by coating a negative electrode slurry on a negative electrode current collector, drying, and cooling. The negative electrode slurry is typically formed by dispersing the negative electrode active material, optional conductive agent, optional adhesive, and other optional additives in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0177] The negative electrode sheet does not exclude any additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet described herein is sandwiched between the negative electrode current collector and the negative electrode film layer and further includes a conductive primer (e.g., composed of a conductive agent and an adhesive) provided on the surface of the negative electrode current collector. In some embodiments, the negative electrode sheet described herein further includes a protective layer covering the surface of the negative electrode film layer.

[0178] [Positive electrode sheet]

[0179] 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 the thickness direction of the positive electrode current collector, and the positive electrode film layer is provided on any one or two of the two facing surfaces of the positive electrode current collector.

[0180] The positive electrode current collector may be a metal foil piece or a composite current collector. An example of the metal foil piece is aluminum foil. The composite current collector may include a polymer material base layer and a metal material layer formed on at least one surface of the polymer material base layer. For example, the metal material may include one or more of aluminum, aluminum alloy, nickel, nickel alloy, titanium, titanium alloy, silver, and silver alloy. For example, the polymer material base layer may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0181] The positive electrode film layer typically includes a positive electrode active material, an optional adhesive, and an optional conductive agent. The positive electrode film layer is typically formed by coating a positive electrode slurry on the positive electrode current collector, drying, and cooling. The positive electrode slurry is typically formed by dispersing the positive electrode active material, the optional conductive agent, the optional adhesive, and any other components in a solvent and stirring the mixture uniformly. The solvent may be, but is not limited to, N-methylpyrrolidone (NMP). For example, the adhesive for the positive electrode film layer may include one or more of polyvinylidene fluoride (PVDF), Teflon (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylic resin. Illustratively, the conductive agent for the positive electrode film layer includes one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0182] As the positive electrode active material, a positive electrode active material for secondary batteries known in the art may be used.

[0183] When the secondary battery of the present application is a lithium ion battery, the positive electrode active material may include, but is not limited to, one or more of lithium transition metal oxides, lithium phosphate, and modified compounds thereof. Examples of the lithium transition metal oxide may 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 modified compounds thereof. Examples of the lithium phosphate may 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 modified compounds thereof.

[0184] In some embodiments, in order to further improve the energy density of the secondary battery, the positive electrode active material for the lithium ion battery may include one or more of lithium transition metal oxides and modified compounds thereof 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 selected from one or more of Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is selected from one or more of N, F, S, and Cl.

[0185] In some embodiments, by way of 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 include one or more of O2, LiFePO4 and LiMnPO4.

[0186] In the present application, the modified compounds of the positive electrode active materials may be obtained by subjecting the positive electrode active materials to doping modification and / or surface coating modification.

[0187] [Electrolyte]

[0188] In some embodiments, the electrolyte is an electrolytic solution, which includes an electrolyte salt and a solvent.

[0189] The type of the electrolyte salt is not specifically limited and may be selected according to actual needs.

[0190] When the secondary battery of the present application is a lithium-ion battery, for example, the electrolyte salt may include one or more of lithium hexafluorophosphate (LiPF), lithium tetrafluoroborate (LiBF), lithium perchlorate (LiClO), lithium hexafluoroarsenate (LiAsF), lithium bisfluorosulfonimide (LiFSI), lithium bistrifluoromethanesulfonimide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium dioxaborate (LiBOB), lithium difluorophosphate (LiPOF), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorooxalate phosphate (LiTFOP).

[0191] The type of the solvent is not specifically limited and may be selected according to actual needs. In some embodiments, the solvent may include one or more of ethylene carbonate (EC), propylene carbonate (PC), methyl ethyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl propyl 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), ethyl methyl sulfone (EMS), and diethyl sulfone (ESE).

[0192] In some embodiments, the electrolyte solution preferably further contains an additive. For example, the additive may include a negative electrode film-forming additive, a positive electrode film-forming additive, or an additive that can improve certain performance of the secondary battery, such as an additive that improves the overcharge performance of the secondary battery, an additive that improves the high-temperature performance of the secondary battery, or an additive that improves the low-temperature power performance of the secondary battery. [Separator]

[0193] 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 may be selected.

[0194] In some embodiments, the separator may be made of one or more of glass fiber, nonwoven 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.

[0195] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet can be wound or laminated to form an electrode assembly.

[0196] In some embodiments, the secondary battery may include an outer package, which may be used to encapsulate the electrode assembly and the electrolyte.

[0197] In some embodiments, the outer packaging may be a hard case, such as a hard plastic case, an aluminum shell, or a steel shell. The outer packaging may also be a soft case, such as a pouch-type soft case. The soft case may be made of plastic, such as one or more of polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0198] In the present application, there is no particular limitation on the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. Figure 2 shows an example of a secondary battery 5 having a rectangular structure.

[0199] In some embodiments, as shown in FIG. 3 , the exterior package may include a housing 51 and a cover plate 53. The housing 51 includes a bottom plate and a side plate connected to the bottom plate, which together form a housing cavity. The housing 51 has an opening communicating with the housing cavity, and the cover plate 53 is used to cover the opening to close the housing cavity. The positive electrode sheet, the negative electrode sheet, and the separator may be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is sealed in the housing cavity. An electrolyte is impregnated into 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 as needed.

[0200] The manufacturing method of the secondary battery of the present application is known. In some embodiments, a secondary battery can be formed by assembling a positive electrode sheet, a separator, a negative electrode sheet, and an electrolyte. For example, the positive electrode sheet, the separator, and the negative electrode sheet can be formed into an electrode assembly by a winding process or a lamination process, and the electrode assembly can be placed in an outer package. After drying, the electrode assembly can be injected with an electrolyte, and the secondary battery can be obtained through processes such as vacuum packaging, standing, chemical formation, and molding.

[0201] 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 multiple, and the specific number may be adjusted according to the application and capacity of the battery module.

[0202] Fig. 4 is a schematic diagram of an exemplary battery module 4. As shown in Fig. 4, in the battery module 4, the multiple secondary batteries 5 may be arranged in order in the length direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the multiple secondary batteries 5 may be fixed in place by fasteners.

[0203] Preferably, the battery module 4 may further include a shell having an accommodating space, and the plurality of secondary batteries 5 are accommodated in the accommodating space.

[0204] In some embodiments, the battery modules can also be assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted depending on the application and capacity of the battery pack.

[0205] 5 and 6 are schematic diagrams of an exemplary battery pack 1. As shown in FIGS. 5 and 6, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 covers the lower housing 3 and is used to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0206] power consumption equipment

[0207] The present application further provides a power consuming device including at least one of the secondary battery, battery module, or battery pack of the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may be, but is not limited to, a mobile terminal (e.g., mobile phone, tablet, laptop, etc.), an electric vehicle (e.g., pure electric vehicle, hybrid electric vehicle, plug-in hybrid electric vehicle, electric bicycle, electric scooter, electric golf cart, electric truck, etc.), a train, a ship, a satellite, an energy storage system, etc.

[0208] The power consumption device may select a secondary battery, a battery module, or a battery pack according to its usage needs.

[0209] 7 is a schematic diagram of an exemplary power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, which may use a battery pack or battery module to meet the high power and high energy density requirements of the power consuming device.

[0210] Other exemplary power consuming devices may be mobile phones, tablets, laptops, etc. Such power consuming devices are typically required to be lightweight and may use secondary batteries as a power source.

[0211] Example

[0212] The following examples will more specifically describe the disclosure of the present application, and these examples are provided for illustrative purposes only, and it will be apparent to those skilled in the art that various modifications and variations can be made within the scope of the disclosure of the present application. Unless otherwise specified, all amounts, percentages, and ratios described in the following examples are based on mass, and all reagents used in the examples are commercially available or synthesized and obtained by conventional methods and can be used as is without further treatment, and all instruments used in the examples are commercially available.

[0213] Example 1

[0214] (1) Manufacturing of carbon materials

[0215] In step 1, 100-mesh flake graphite is mechanically crushed, classified, spheroidized, and refined to obtain natural spherical graphite. The volume distribution particle diameter Dv50 is 17 μm and the total pore volume is 54 × 10 -3 cm 3 / g, and the degree of graphitization is 96.7%.

[0216] In step 2, the obtained natural spherical graphite and petroleum asphalt (softening point temperature 116°C, volume distribution particle size Dv50 3.7μm, coking value 32%) are mixed in a mass ratio of 100:15 in a VC mixer for 30 minutes, and then the mixed material is placed in a drum furnace, heated to 220°C at a rate of 5°C / min and kept at that temperature for 1.5 hours (first heating process), then heated to 1100°C at a rate of 5°C / min and kept at that temperature for 2 hours (second heating process), and after completion, cooled to room temperature to obtain an intermediate.

[0217] In step 3, the obtained intermediate is placed in an Acheson graphitization furnace, heated to 2345°C, and kept at that temperature for 2 hours. After completion, the intermediate is demagnetized and sorted to obtain the carbon material.

[0218] (2) Manufacture of button batteries (half cells)

[0219] The carbon material prepared above was mixed with styrene butadiene rubber (SBR) as an adhesive, sodium carboxymethyl cellulose (CMC) as a thickener, and carbon black as a conductive agent in a mass ratio of 96.2:1.8:1.2:0.8 with an appropriate amount of deionized water as a solvent, and stirred thoroughly to form a uniform anode slurry. The anode slurry was then uniformly coated on the surface of a copper foil anode current collector and dried in an oven before being prepared for use. Ethylene carbonate (EC), methyl ethyl carbonate (EMC), and diethyl carbonate (DEC) were mixed in a volume ratio of 1:1:1 to obtain an organic solvent. LiPF6 was then dissolved in the organic solvent to prepare a 1 mol / L electrolyte solution. Then, lithium metal flakes were used as the counter electrode and polyethylene (PE) film was used as the separator. CR2430 button cells were then assembled in an argon-protected glove box.

[0220] (3) Manufacture of secondary batteries (full batteries)

[0221] The carbon material, conductive carbon black (Super P), adhesive styrene butadiene rubber, and thickener sodium carboxymethyl cellulose are mixed in a weight ratio of 96:1:1:2 with an appropriate amount of deionized water to form anode slurry. The cathode slurry is applied to two surfaces of copper foil as anode current collector, and then dried and cooled to obtain anode sheets.

[0222] LiFePO4 is mixed with conductive carbon black and polyvinylidene fluoride in a weight ratio of 96:2.5:1.5, and an appropriate amount of NMP solvent is added and stirred uniformly to obtain a positive electrode slurry. The positive electrode slurry is then applied to two surfaces of aluminum foil, which serves as a positive electrode current collector, and after drying and cooling, a positive electrode sheet is obtained.

[0223] A 12 μm thick polypropylene film is used as a separator, which is then arranged in sequence with the positive electrode sheet and negative electrode sheet prepared above, with the separator being placed in the center between the positive electrode sheet and the negative electrode sheet to provide isolation, and then wound up to obtain an electrode assembly. The electrode assembly is placed in an outer packaging, dried, and then injected with the same electrolyte as used in the manufacture of the button battery above. After vacuum packaging, standing, chemical formation, molding, and other processes, a secondary battery is obtained.

[0224] Comparative Example 1

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

[0226] 100 mesh flake graphite was mechanically crushed, classified, spheroidized, and refined to obtain natural spherical graphite. Its volume distribution particle diameter Dv50 was 17 μm and total pore volume was 54 × 10 -3 cm 3 / g, graphitization degree is 96.7%, and then the obtained natural spherical graphite is used as the carbon material to manufacture half cells and full cells.

[0227] Comparative Example 2

[0228] The manufacturing methods for the half-cell and full-cell are similar to those in Example 1, with the difference being the manufacturing process for the carbon material.

[0229] 100 mesh flake graphite was mechanically crushed, classified, spheroidized, and refined to obtain natural spherical graphite. Its volume distribution particle diameter Dv50 was 17 μm and total pore volume was 54 × 10 -3 cm 3 / g, and the degree of graphitization is 96.7%.

[0230] The obtained natural spherical graphite and petroleum asphalt (softening point temperature 116°C, volume distribution particle size Dv50 3.7μm, coking value 32%) were mixed in a mass ratio of 100:15 in a VC mixer for 30 minutes, and then the mixed material was graphitized at 3200°C for 10 hours, and after completion, it was cooled to room temperature to obtain the carbon material.

[0231] Comparative Example 3

[0232] The manufacturing methods for the half-cell and full-cell are similar to those in Example 1, with the difference being the manufacturing process for the carbon material.

[0233] 100 mesh flake graphite was mechanically crushed, classified, spheroidized, and refined to obtain natural spherical graphite. Its volume distribution particle diameter Dv50 was 17 μm and total pore volume was 54 × 10 -3 cm 3 / g, and the degree of graphitization is 96.7%.

[0234] The obtained natural spherical graphite and petroleum asphalt (softening point temperature 116°C, volume distribution particle size Dv50 3.7μm, coking value 32%) were mixed in a mass ratio of 100:15 in a VC mixer for 30 minutes, and then the mixed material was carbonized at 1300°C for 2 hours, and after completion, it was cooled to room temperature to obtain the carbon material.

[0235] Comparative Example 4

[0236] The manufacturing methods for the half-cell and full-cell are similar to those in Example 1, with the difference being the manufacturing process for the carbon material.

[0237] 100 mesh flake graphite was mechanically crushed, classified, spheroidized, and refined to obtain natural spherical graphite. Its volume distribution particle diameter Dv50 was 17 μm and total pore volume was 54 × 10 -3 cm 3 / g, and the degree of graphitization is 96.7%.

[0238] The asphalt was added to the washing oil and stirred at high speed to fully dissolve the asphalt and obtain an asphalt solution. 100g of natural spherical graphite was placed in the reactor and vacuumed for 60 minutes. When the reactor reached a vacuum of 0.07MPa, the asphalt solution suction valve was opened and all of the asphalt solution was sucked into the reactor. After the liquid was poured in, the suction valve was closed and the vacuum was stopped. The mixture was then stirred at high speed for 40 minutes, pressurized (12MPa), and after the immersion was complete, the pressure was reduced to equalize the pressure inside and outside the reactor. Nitrogen was then injected and the reactor was heated to 230°C to remove the washing oil. After the washing oil was completely removed from the reactor, the reactor was heated to 410°C at a heating rate of 5°C / min under a pressure of 1.5MPa, and the thermal polymerization reaction was carried out for 10 minutes. The material was then cooled to room temperature and removed. The obtained material is held at isostatic pressure (10 MPa) for 30 minutes, then graphitized at high temperature (2800°C) for 4 hours, cooled to room temperature, and then pulverized. The pulverized material is uniformly mixed with asphalt in a 100:5 ratio, carbonized at 1000°C for 5 hours under nitrogen protection, and cooled to room temperature to obtain a carbon material with no internal pores.

[0239] Examples 2 to 23

[0240] The manufacturing methods of the half-cell and the whole cell were similar to those in Example 1, except that the manufacturing process parameters of the carbon material were adjusted. See Table 1 for details.

[0241] [Table 1-1]

[0242] [Table 1-2]

[0243] [Table 1-3]

[0244] Performance Test

[0245] (1) Total pore volume test of carbon materials

[0246] A certain mass of carbon material sample (e.g., 1.5 to 3.5 g) is placed in a sample tube, dried, and then degassed at 200 °C for 2 hours. It is then placed in a Tristar II 3020 instrument analysis station for testing to obtain the total pore volume V of the carbon material. During the test, the adsorption gas may be nitrogen, and the adsorption temperature may be 77 K (K represents the Kelvin temperature).

[0247] (2) Carbon material powder compression density test

[0248] According to GB / T24533-2009, 1g of carbon powder is weighed out to a base area of 1.327cm 2 The powder is compressed to a pressure of 5000 kg (equivalent to 50,000 N), and the pressure is maintained for 30 seconds. The pressure is then released and maintained for 10 seconds. The powder is then recorded and calculated to obtain the powder compaction density P of the carbon material at a pressure of 50,000 N. A UTM7305 type electronic pressure tester may be used as the test device.

[0249] (3) Total pore area test in the outer and inner regions of the carbon material

[0250] The adhesive and carbon powder were mixed uniformly and then coated on copper foil. The mixture was then dried at 60°C for 30 hours to prepare the sample for use. The sample was then cut into 6mm x 6mm pieces and attached to the sample stage of a CP-type argon ion cross-section polisher. A plasma beam was used to cut the sample, capturing a cross-section of the carbon material. The cross-section of the carbon material particle passed through the center of the particle. The test equipment could be a JEOL IB-09010 CP-type argon ion cross-section polisher from Japan. The cross-section of the carbon material was scanned using a scanning electron microscope. For testing, see JY / T010-1996. The test equipment could be a Sigma 300 scanning electron microscope from ZEISS, Germany. The region extending 0.25L from the surface of the carbon material particle to the interior of the particle was referred to as the external region, and the region inside the external region was referred to as the internal region, where L represents the minor axis length of the carbon material particle. Image processing software was used to calculate the total pore area S1 of the external region and the total pore area S2 of the internal region of the carbon material particle. The image processing software may be AVIZO.

[0251] (4) Initial Coulombic efficiency test of carbon materials

[0252] At 25°C, the button battery was first discharged at a constant current of 0.15 mA to 0.005 V, left for 5 minutes, and then discharged at a constant current of 10 μA to 0.005 V. The first-cycle discharge capacity of the button battery was recorded. It was then charged at a constant current of 0.3 mA to 2.0 V, and the first-cycle charge capacity of the button battery was recorded. The first-cycle coulombic efficiency (%) of the carbon material = first-cycle charge capacity of the button battery / first-cycle discharge capacity of the button battery × 100%.

[0253] (5) Secondary battery cycle performance test

[0254] At 25°C, the secondary battery prepared above was charged at a constant current of 1C to the upper cutoff voltage (corresponding to 100% SOC), then charged at a constant voltage until the current reached 0.05C. After leaving the battery for 5 minutes, the secondary battery was discharged at a constant current of 1C to the lower cutoff voltage (corresponding to 0% SOC). The discharge capacity at this time was recorded as the 1-cycle discharge capacity. The secondary battery was subjected to a cycle charge-discharge test according to the method described above, and the discharge capacity after each cycle was recorded. The 2000-cycle capacity retention (%) of the secondary battery at 25°C = discharge capacity after 2000 cycles / 1-cycle discharge capacity × 100%.

[0255] (6) Secondary battery storage performance test

[0256] At 25°C, the secondary battery prepared above is charged at a constant current of 1 C to an upper cutoff voltage (corresponding to 100% SOC), then charged at a constant voltage until the current reaches 0.05 C, and after leaving it for 5 minutes, the secondary battery is discharged at a constant current of 1 C to a lower cutoff voltage (corresponding to 0% SOC), and the discharge capacity at this time is recorded as the discharge capacity before storage.

[0257] At 25°C, the secondary battery prepared above is charged at a constant current of 1 C to the upper cutoff voltage (corresponding to 100% SOC), and then charged at a constant voltage until the current reaches 0.05 C. The secondary battery is then stored in an incubator at 60°C, and the test is stopped until the discharge capacity of the secondary battery after storage reaches 90% of the discharge capacity before storage, and the number of days the secondary battery has been stored is recorded.

[0258] [Table 2-1]

[0259] [Table 2-2]

[0260] [Table 2-3]

[0261] The carbon materials produced in Examples 1 to 23 all had parameters such as specific surface area, volume distribution particle size, tap density, and graphitization degree within the ranges described in the present specification.

[0262] As can be seen from the test results in Table 2, the carbon material is 4.1 × 10 -3 ≦V×P≦12.0×10 -3 When the above condition is satisfied, the battery can achieve high initial coulombic efficiency, high energy density, and good cycle and storage performance. -3 ≦V×P≦10.0×10 -3 and preferably 4.4 × 10 -3 ≦V×P≦8.0×10 -3 When the above condition is satisfied, the overall performance of the battery is further improved.

[0263] The carbon materials produced in Comparative Examples 1 to 4 all had a carbon content of 4.1 × 10 -3 ≦V×P≦12.0×10 -3 and none of them can provide a battery with high initial coulombic efficiency, high energy density, and good cycle performance and storage performance at the same time.

[0264] In Comparative Example 1, untreated natural spherical graphite was used as the carbon material, which had many pores inside and a large total pore volume. As can be seen from the test results in Table 2, the gram capacity, initial coulombic efficiency, cycle performance, and storage performance of the battery manufactured using this method were all low, and when the battery cycle count did not reach 2000 cycles, the discharge capacity was reduced to 80% of the 1-cycle discharge capacity.

[0265] The carbon materials produced in Comparative Examples 2 and 3 were natural spherical graphite coated with a carbon layer, but the carbon layer was present only on the surface of the natural spherical graphite and did not provide an effective packing effect. In this case, the total pore volume of the carbon material particles was large and / or the compressed density was high, and the carbon layer was unable to effectively prevent the electrolyte from penetrating into the pore structure inside the particles. Furthermore, the effects of improving the initial coulombic efficiency, cycle performance, and storage performance of the battery were limited.

[0266] In the carbon material preparation in Comparative Example 4, the filler material is filled into all the pore structures inside the natural spherical graphite particles by isostatic pressure, and the total pore volume of the carbon material is too small. As a result, the volume change of the carbon material particles is large during the process of escaping and inserting active ions, making the particles more susceptible to damage, and further limiting the effect of improving the cycle performance and storage performance of the battery. In addition, the presence of a large amount of soft carbon inside and / or on the surface of the carbon material particles increases side reactions on the particle surface, thereby affecting the cycle performance and storage performance of the battery. At the same time, the preparation process is complicated and not suitable for large-scale production.

[0267] As can be seen from the test results in Table 2, the total pore volume V of the carbon material was 2.3 × 10 -3 ~7.5×10 -3 cm 3 / g, preferably 2.4 × 10 -3 ~6.0×10 -3 cm 3 / g, the overall performance of the battery is further improved.

[0268] As can be seen from the test results in Table 2, the powder compaction density P of the carbon material at a pressure of 50,000 N is 1.80 to 2.10 g / cm 3 , preferably 1.82 to 2.06 g / cm 3 When the total battery performance is further improved.

[0269] As can be seen from the test results in Table 2, when the carbonaceous particles further satisfy S2 > S1, preferably 1.5 ≦ S2 / S1 ≦ 460, and more preferably 1.7 ≦ S2 / S1 ≦ 380, the overall performance of the battery is further improved. In this case, the carbonaceous particles are further characterized by a large number of pores and / or large pore size in the inner region, while a small number of pores and / or small pore size in the outer region. The pore structure in the inner region of the carbonaceous particles can ensure expansion space necessary for volume changes of the carbonaceous particles, thereby reducing the risk of new interface formation due to damage to the carbonaceous particles, further reducing the occurrence of side reactions and irreversible capacity loss of the secondary battery. The small number of pores and / or small pore size in the outer region of the carbonaceous particles can provide the carbonaceous particles with a more stable structure, minimizing the infiltration of the electrolyte into the pore structure inside the carbonaceous particles, thereby reducing the occurrence of side reactions and the consumption of active ions due to the formation of an SEI film inside the particles. Therefore, a carbon material that further satisfies the above structural characteristics can further improve the overall performance of the battery.

[0270] The present application is not limited to the above-described embodiments. The above-described embodiments are merely exemplary, and any embodiment that has a configuration substantially similar to the technical idea and produces similar effects within the scope of the technical solution of the present application is included in the technical scope of the present application. Furthermore, other embodiments constructed by adding various modifications to the embodiments that a person skilled in the art can conceive, or by combining some of the components of the embodiments, are also included in the scope of the present application, as long as they do not deviate from the gist of the present application.

Claims

1. A carbon material, The carbon material includes a pore structure. The total pore volume of the carbon material is denoted as V, and the powder compaction density of the carbon material at a pressure of 50,000 N is denoted as P. The carbon material has a pore size of 4.1 × 10 ―３ ≦V×P≦12.0×10 ―３ and the total pore volume V of the carbon material is expressed in units of cm ３ / g, and the powder compressed density P of the carbon material at a pressure of 50,000 N is in g / cm ３ That is, A carbon material characterized by:

2. 4.3 x 10 ―３ ≦V×P≦10.0×10 ―３ and preferably 4.4 × 10 ―３ ≦V×P≦8.0×10 ―３ and / or The total pore volume V of the carbon material is 2.3 × 10 ―３ ~7.5 x 10 ―３ cm ３ / g, preferably 2.4×10 ―３ ~6.0 x 10 ―３ cm ３ / g, and / or The powder compression density P of the carbon material at a pressure of 50,000 N is 1.80 to 2.10 g / cm ３ and preferably 1.82 to 2.06 g / cm ３ That is, The carbon material according to claim 1 .

3. The carbon material has a pore area of 0.1 μm 2 and preferably has a pore area of 0.12 to 1.5 μm 2 and one or more pore structures, 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, and the outer region refers to a region extending from the particle surface of the carbon material to the inside of the particle by a distance of 0.25L, where L refers to the minor axis length of the carbon material particle, and the total pore area of the outer region is S. １ and the total pore area of the inner region is S ２ and S ２ >S １ That is, The carbon material according to any one of claims 1 to 3.

5. 1.5≦S ２ / S １ ≦460, and preferably 1.7≦S ２ / S １ ≦380, The carbon material according to claim 4 .

6. 0.01 μm 2 ≦S １ ≦15.0 μm 2 and preferably 0.02 μm 2 ≦S １ ≦12.0 μm 2 and / or 2.5 μm 2 ≦S ２ ≦25.0 μm 2 and preferably 3.0 μm 2 ≦S ２ ≦22.5 μm 2 and / or L≧4 μm, preferably 6 μm≦L≦18 μm; 6. The carbon material according to claim 4 or 5.

7. The area of the pore structure in the outer region of the carbon material is 0.13 μm 2 or less, preferably 0.1 μm 2 and / or The inner region of the carbon material has an area of 0.1 μm 2 and preferably has an area of 0.12 to 2.0 μm 2 and one or more pore structures, The carbon material according to any one of claims 4 to 6.

8. The layer spacing in the outer region of the carbon material is defined as d １ and the layer spacing in the internal region of the carbon material is represented by d ２ When written as above, the carbon material is d １ ≧d ２ Fulfilling Preferably, d １ >d ２ That is, The carbon material according to any one of claims 4 to 7.

9. d １ is between 0.33565 and 0.33600 nm, and / or d ２ is 0.33553 to 0.33575 nm, The carbon material according to claim 8 .

10. The carbon material satisfies at least one of the following (1) to (6): (1) The specific surface area of the carbon material is 0.6 to 2.0 m ２ / g, preferably 0.8 to 1.6 m ２ / g, (2) The volume distribution particle diameter Dv50 of the carbon material is 8.0 to 20.0 μm, preferably 8.5 to 19.0 μm; (3) The volume distribution particle diameter Dv10 of the carbon material is 5.0 to 15.0 μm, preferably 6.0 to 14.0 μm; (4) The volume distribution particle diameter Dv90 of the carbon material is 16.0 to 35.0 μm, preferably 17.0 to 34.0 μm; (5) The (Dv90-Dv10) / Dv50 of the carbon material is 0.5 to 1.5, preferably 0.7 to 1.45; (6) The appearance of the carbon material includes one or more of a block shape, a spherical shape, and a quasi-spherical shape. The carbon material according to any one of claims 1 to 9.

11. The carbon material satisfies at least one of the following conditions: (1) The degree of graphitization of the carbon material is 94.0% to 98.5%, preferably 94.5% to 98.0%; (2) The tap density of the carbon material is 0.80 to 1.30 g / cm ３ and preferably 0.85 to 1.28 g / cm ３ and (3) The gram capacity of the carbon material is 350 to 371 mAh / g, preferably 353 to 370 mAh / g; The carbon material according to any one of claims 1 to 10.

12. A method for producing a carbon material, comprising: Step 1: providing a feedstock having a plurality of pore structures; The raw material and the filler material are mixed uniformly in a predetermined ratio, and then heated to a first temperature T １ At the first time t １ Step 2: Incubating to obtain an intermediate; The obtained intermediate is heated to a second temperature T ２ At the second time t ２ and step 3 of obtaining a carbon material by keeping the temperature. The carbon material includes a pore structure. The total pore volume of the carbon material is denoted as V, and the powder compaction density of the carbon material at a pressure of 50,000 N is denoted as P. The carbon material has a pore size of 4.1 × 10 －３ ≦V×P≦12.0×10 －３ and the total pore volume V of the carbon material is expressed in units of cm ３ / g, and the powder compressed density P of the carbon material at a pressure of 50,000 N is in g / cm ３ That is, A method for producing a carbon material, comprising:

13. The raw material satisfies at least one of the following (1) to (4): (1) The raw material includes natural graphite, and preferably, the natural graphite includes one or more of flake graphite, natural spheroidal graphite, and microcrystalline graphite; (2) The volume distribution particle diameter Dv50 of the raw material is 9.0 to 20.0 μm, preferably 10.0 to 19.0 μm; (3) The total pore volume of the raw material is ≧10×10 ―３ cm ３ / g, preferably 20×10 ―３ ~60 x 10 ―３ cm ３ / g, (4) The graphitization degree of the raw material is ≧94.0%; 13. The method of claim 12.

14. The filling material satisfies at least one of the following (1) to (3): (1) The softening point temperature of the filler material is 95 to 158°C, preferably 100 to 145°C; (2) the caulking value of the filler material is 15% to 42%, preferably 20% to 38%; (3) The volume distribution particle diameter Dv50 of the filler material is 6 μm or less, preferably 1 to 5 μm.

14. The method according to claim 12 or 13.

15. The filler material comprises one or more of coal asphalt and petroleum asphalt; 15. The method of claim 14.

16. The mass ratio of the filler material to the raw material is (10 to 30):100, preferably (11 to 20):

100.

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

17. The raw material and the filling material are uniformly mixed in a predetermined ratio, and then heated to a first temperature T １ The temperature increase process is a stepwise temperature increase process, and preferably includes a first temperature increase process and a second temperature increase process.

17. The method according to any one of claims 12 to 16.

18. In the first temperature-raising process, the temperature is raised to 200 to 250 ° C. and kept at that temperature for 1 to 3 hours, and / or In the second temperature increase process, the first temperature T １ and maintaining the temperature for a first time t １ Keep warm, 18. The method of claim 17.

19. The first temperature T １ Heat up to 19. The method according to any one of claims 12 to 18.

20. the first temperature T １ is 700 to 1200°C, preferably 800 to 1100°C, and / or The first time t １ is 1 to 5 h, preferably 2 to 4 h; 20. The method according to any one of claims 12 to 19.

21. Said second temperature T ２ is between 1950 and 2550°C, preferably between 2050 and 2500°C, and / or The second time t ２ is 1.5 to 6 h, preferably 2 to 5 h; 21. The method according to any one of claims 12 to 20.

22. A secondary battery comprising a negative electrode sheet, the negative electrode sheet comprising the carbon material according to any one of claims 1 to 11 or a carbon material produced by the method according to any one of claims 12 to 21. A secondary battery characterized by:

23. 23. A power consuming device comprising the secondary battery of claim 22.

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