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

Abstract

This application provides a carbon material, a method for manufacturing the same, a secondary battery and a power consumption device including the same. The carbon material includes a pore structure. When the adsorption amount of 100 g of the carbon material to linseed oil is A and the specific surface area of the carbon material is B, the carbon material satisfies 36 ≦ A×B ≦ 75. The unit of the adsorption amount A of 100 g of the carbon material to linseed oil is ml, and the unit of the specific surface area B of the carbon material is m 2 / g. The carbon material provided by this application can achieve both high initial Coulomb efficiency, high energy density, good cycle performance and storage performance in secondary batteries.

Description

[Technical Field]

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

[0002] In recent years, secondary batteries have been widely applied in many fields, including energy storage and power systems such as hydroelectric, thermal, wind, and solar power plants, as well as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, and aerospace. As the range of applications for secondary batteries expands, serious challenges have been raised regarding their performance. For example, secondary batteries are required to achieve a balance between high energy density and long lifespan. The negative electrode active material is a crucial component of secondary batteries and affects their performance. Currently, negative electrode active materials mainly contain graphite, but the problem faced in conventional technology is that high-capacity graphite is difficult to achieve simultaneously with high initial Coulomb efficiency, and at the same time, it is difficult to achieve good cycle performance and storage performance in secondary batteries. [Overview of the project]

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

[0004] A first aspect of this application provides a carbon material comprising a porous structure, wherein the amount of adsorption of 100g of the carbon material onto linseed oil is A, and the specific surface area of ​​the carbon material is B, such that the carbon material satisfies 36 ≤ A × B ≤ 75, the unit of the amount of adsorption A of 100g of the carbon material onto linseed oil is ml, and the unit of the specific surface area B of the carbon material is m 2 It is / g.

[0005] The carbon material provided in this application effectively reduces irreversible capacity loss in secondary batteries, improves the capacity performance characteristics of secondary batteries, and enables secondary batteries to achieve high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance simultaneously.

[0006] In any embodiment of this application, 38 ≤ A × B ≤ 65, preferably 39 ≤ A × B ≤ 55. In this case, it is advantageous to better achieve a high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance in the secondary battery.

[0007] In any embodiment of this application, the amount A adsorbed by 100g of the carbon material into linseed oil is 30ml to 50mL, preferably 35ml to 47mL. When the amount adsorbed by the carbon material into linseed oil is within the above range, the side reaction activity of the carbon material particle surface is low, which reduces the consumption of active ions due to the formation of the SEI film, avoids the influence on the transport of active ions due to the particle surface being too dense, and is also advantageous in forming a rational pore structure between the particles of the negative electrode film layer, thereby improving the wettability of the negative electrode sheet to the electrolyte.

[0008] In any embodiment of this application, the specific surface area B of the carbon material is 0.5 m². 2 / g~2.1m 2 The value is / g, preferably 0.7m 2 / g~1.8m 2 The value is / g. When the specific surface area of ​​the carbon material is within the above range, the carbon material has low surface side reaction activity, which reduces the consumption of active ions due to the formation of the SEI film and can improve the initial Coulomb efficiency of the carbon material, while also being able to have high active ion transport performance.

[0009] In any embodiment of this application, the carbon material has a pore area of ​​0.1 μm². 2 It contains one or more pore structures as described above, preferably with a pore area of ​​0.12 μm². 2 ~2.5μm 2It contains one or more pore structures. When the carbon material further contains a pore structure having the above pore area, the pore structure can secure an expansion space necessary for the volume change of the carbon material particles, thereby further reducing the risk of generation of a new interface due to crushing of the carbon material particles, reducing the occurrence of side reactions, reducing the irreversible capacity loss of the secondary battery, and further improving the cycle performance and storage performance of the secondary battery.

[0010] In any embodiment of the present application, the carbon material includes an external region and an internal region located inside the external region. The external region is a region extending 0.25L from the particle surface of the carbon material to the inside of the particle, where L is the short axis length of the carbon material particle. Let the total pore area of the external region be S1 and the total pore area of the internal region be S2, and S2 > S1. When the carbon material particles further satisfy S2 > S1, the irreversible capacity loss of the secondary battery can be effectively reduced, the capacity performance characteristics of the secondary battery can be improved, and the secondary battery can better achieve high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0011] In any embodiment of the present application, 1.3 ≤ S2 / S1 ≤ 450, and preferably, 1.8 ≤ S2 / S1 ≤ 400. When S2 / S1 satisfies the above range, the secondary battery can better achieve high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0012] In any embodiment of the present application, 0.01 μm 2 ≤ S1 ≤ 12.0 μm 2 and preferably, 0.02 μm 2 ≤ S1 ≤ 7.0 μm 2 is. When the total pore area of the external region of the carbon material is within the above range, the carbon material particles have fewer surface defects and a more stable structure, can avoid the penetration of the electrolyte into the pore structure inside the carbon material particles as much as possible, reduce the occurrence of side reactions, reduce the consumption of active ions due to the formation of the SEI film inside the carbon material particles, and at the same time do not affect the transport performance of active ions and electrons.

[0013] In any embodiment of this application, 2.5 μm 2 ≤S2 ≤ 25.0 μm 2 Preferably, 3.0 μm 2 ≤S2 ≤ 20.5 μm 2 Therefore, when the total pore area of ​​the internal region of the carbon material is within the above range, a sufficient and stable expansion space can be secured for the volume change of the carbon material particles, the risk of new interfaces being generated due to the fragmentation of carbon material particles can be reduced, the occurrence of side reactions on the new interface surface can be decreased, and the consumption of active ions due to the formation of SEI films on the new interface surface can be reduced, while the capacity and initial Coulomb efficiency of the carbon material can be improved.

[0014] In any embodiment of this application, L ≥ 4 μm, preferably 6 μm ≤ L ≤ 18 μm.

[0015] In any embodiment of this application, the area of ​​the pore structure in the external region of the carbon material is 0.2 μm². 2 The following, preferably 0.15 μm 2 The following is true: By controlling the size of the area of ​​the pore structure in the external region of the carbon material to within the above range, the external region of the carbon material can have a dense structure, thereby effectively reducing surface defects in the carbon material, improving the structural stability of the carbon material, and preventing the electrolyte from penetrating the pore structure inside the carbon material particles as much as possible, which in turn can further improve the cycle performance and storage performance of the secondary battery.

[0016] In any embodiment of this application, the internal region of the carbon material has an area of ​​0.15 μm 2 The pore structure contains one or more of the above characteristics, preferably with an area of ​​0.18 μm². 2 ~2.5μm 2 The material contains one or more pore structures of the above size. By including pore structures of the above size within the internal region of the carbon material, a sufficient and stable expansion space is secured for volume changes of the carbon material particles, reducing the risk of fragmentation of the carbon material particles while improving the compressive density of the carbon material.

[0017] In any embodiment of this application, if the interlayer distance of the outer region of the carbon material is d1 and the interlayer distance of the inner region of the carbon material is d2, then the carbon material satisfies d1 ≥ d2, preferably d1 > d2. A large interlayer distance in the outer region of the carbon material is advantageous for the rapid insertion and removal of active ions, thus further improving the dynamic performance of the secondary battery. A small interlayer distance in the inner region of the carbon material is advantageous for improving the gram capacity and compressive density of the carbon material, thus further improving the energy density of the secondary battery.

[0018] In any embodiment of this application, d1 is 0.33565 nm to 0.33610 nm.

[0019] In any embodiment of this application, d2 is 0.33557 nm to 0.33585 nm.

[0020] In any embodiment of this application, the degree of graphitization of the carbon material is 94% to 98%, preferably 95% to 97%. Having the degree of graphitization of the carbon material within the above range is advantageous for improving the energy density of the secondary battery, and is also advantageous for improving the cycle performance, storage performance and / or rate performance of the secondary battery.

[0021] In any embodiment of this application, the La(110) of the carbon material is 100 nm to 150 nm, preferably 110 nm to 130 nm.

[0022] In any embodiment of this application, the Lc(002) of the carbon material is 20 nm to 45 nm, preferably 28 nm to 40 nm.

[0023] When the La(110) and / or Lc(002) of the carbon material are within an appropriate range, it is advantageous for the carbon material to have high crystallinity and / or degree of graphitization, advantageous for improving the gram capacity of the carbon material, advantageous for improving the active ion and electron transport performance of the negative electrode film layer, and further advantageous for improving the cycle performance, storage performance and / or rate performance of the secondary battery.

[0024] In any embodiment of this application, the volume-distributed particle size Dv50 of the carbon material is 8.0 μm to 24.0 μm, preferably 9.5 μm to 22.5 μm.

[0025] In any embodiment of this application, the volume-distributed particle size Dv10 of the carbon material is 5.0 μm to 15.0 μm, preferably 6.0 μm to 14.0 μm.

[0026] In any embodiment of this application, the volume-distributed particle size Dv90 of the carbon material is 16.0 μm to 35.0 μm, preferably 17.0 μm to 34.0 μm.

[0027] When the volume distribution particle size Dv10, Dv50 and / or Dv90 of the carbon material are within the above range, it is advantageous for improving the transport performance of active ions and electrons, and is also advantageous for forming a rational pore structure between particles in the negative electrode film layer, thereby further improving the cycle performance and / or rate performance of the secondary battery.

[0028] In any embodiment of this application, the (Dv90-Dv10) / Dv50 of the carbon material is 0.55 to 1.55, preferably 0.8 to 1.4. When the (Dv90-Dv10) / Dv50 of the carbon material is within the above range, its particle deposition performance is good, which is advantageous for improving the compressive density of the negative electrode film layer, and thus the energy density of the secondary battery can be further improved. It is also advantageous for forming a rational pore structure between the particles of the negative electrode film layer.

[0029] In any embodiment of this application, the tap density of the carbon material is 0.80 g / cm³.3 ~1.32 g / cm³ 3 The concentration is preferably 0.82 g / cm³. 3 ~1.28 g / cm³ 3 Therefore, if the tap density of the carbon material is within the above range, the compressive density of the negative electrode sheet can be improved, and the energy density of the secondary battery can be further improved. It is also advantageous to form a rational pore structure between the particles of the negative electrode film layer, improving the transport performance of active ions and electrons, and thereby improving the cycle performance and storage performance of the secondary battery.

[0030] In any embodiment of this application, the gram capacity of the carbon material is 355 mAh / g to 371 mAh / g, preferably 360 mAh / g to 370 mAh / g. When the gram capacity of the carbon material is within the above range, the energy density of the secondary battery can be improved.

[0031] In any embodiment of this application, the form of the carbon material includes one or more of the following: bulk, spherical, and substantially spherical.

[0032] A second aspect of this application is a method for producing a carbon material, comprising: step 1 supplying a raw material having a plurality of pore structures; step 2 uniformly mixing the raw material and a filler in a predetermined ratio, then maintaining the mixture at a first temperature T1 for a first time t1 to obtain an intermediate; and step 3 maintaining the obtained intermediate at a second temperature T2 for a second time t2 to obtain a carbon material, wherein the carbon material contains pore structures, and if the amount of adsorption A of 100g of the carbon material into linseed oil is A, and the specific surface area of ​​the carbon material is B, then the carbon material satisfies 36 ≤ A × B ≤ 75, the unit of the amount of adsorption A of 100g of the carbon material into linseed oil is ml, and the unit of the specific surface area B of the carbon material is m 2 This invention provides a method for producing carbon material in a quantity of / g.

[0033] In any embodiment of this application, the raw material comprises natural graphite, preferably the natural graphite comprises one or more of flaky graphite, natural spheroidal graphite, and microcrystalline graphite.

[0034] In any embodiment of this application, the volume distribution particle size Dv50 of the raw material is 8.5 μm to 24.0 μm, preferably 10.5 μm to 22.5 μm.

[0035] In any embodiment of this application, the ash content in the raw material is 1 wt% or less. A low ash content in the raw material is advantageous for the carbon material to have fewer surface defects.

[0036] In any embodiment of this application, the softening point temperature of the filler is 110°C to 175°C, preferably 120°C to 170°C. Having the softening point temperature of the filler within the above range is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping A×B of the carbon material within an appropriate range, advantageous for adjusting the pore size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and also advantageous for adjusting S2 / S1 within an appropriate range.

[0037] In any embodiment of this application, the caulking value of the filler is 26% to 50%, preferably 33% to 45%. When the caulking value of the filler is within the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping A×B of the carbon material within an appropriate range, advantageous for adjusting the pore size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and also advantageous for adjusting S2 / S1 within an appropriate range.

[0038] In any embodiment of this application, the volume distribution particle size Dv50 of the filler is 6 μm or less, preferably 1 μm to 5 μm. This is advantageous for the filler to fill the pore structure of the raw material after it has melted due to heat, and is also advantageous for improving the uniformity of the dispersion between the filler and the raw material.

[0039] In any embodiment of this application, the content of quinoline insoluble matter in the filler is 1 wt% or less, preferably 0.8 wt% or less.

[0040] In any embodiment of this application, the filler includes one or more of coal pitch and petroleum pitch.

[0041] In any embodiment of this application, the mass ratio of the filler to the raw material is (10-32):100, preferably (10-25):100. This is advantageous in that the carbon material has an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, is advantageous in that the A×B of the carbon material is within an appropriate range, is advantageous in that the pore size and / or number of pores in the external and internal regions of the carbon material are within an appropriate range, and is also advantageous in that the S2 / S1 is within an appropriate range.

[0042] In any embodiment of this application, the heating process, which involves uniformly mixing the raw materials and the filler in a predetermined ratio and then raising the temperature to a first temperature T1, is a stepwise heating process, and preferably includes a first heating process, a second heating process, and a third heating process.

[0043] In any embodiment of this application, the first heating process heats up to 200°C to 250°C and maintains the temperature for 0.5h to 2h.

[0044] In any embodiment of this application, the second heating process heats up to 450°C to 550°C and maintains the temperature for 0.5h to 2h.

[0045] In any embodiment of this application, the third heating process heats up to the first temperature T1 and maintains the temperature for a first time t1.

[0046] In any embodiment of this application, the temperature is raised to the first temperature T1 at a rate of 1°C / min to 10°C / min, preferably 1.5°C / min to 8°C / min.

[0047] In any embodiment of this application, the first temperature T1 is 700°C to 1100°C, preferably 750°C to 1100°C.

[0048] In any embodiment of this application, the first time t1 is 0.5h to 5h, preferably 0.5h to 3h.

[0049] Adjusting one or more of the heating rate, first temperature, first time, heating process, etc., within the above range is advantageous for producing the desired carbon material. For example, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, to keep A×B of the carbon material within an appropriate range, to adjust the pore size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and to adjust S2 / S1 within an appropriate range.

[0050] In any embodiment of this application, the second temperature T2 is 1920°C to 2520°C, preferably 2050°C to 2400°C.

[0051] In any embodiment of this application, the second time t2 is 1h to 6h, preferably 2h to 5h.

[0052] By adjusting one or more of the second temperature and second time within the above range, it is advantageous to reduce the content of irregular carbon in the carbon material, to ensure that the carbon material has an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, and to keep the A × B of the carbon material within an appropriate range.

[0053] A third aspect of this application provides a secondary battery comprising a negative electrode sheet containing the carbon material of the first aspect of this application or a carbon material manufactured by the method of the second aspect of this application.

[0054] A fourth aspect of this application provides a power consumption device including a secondary battery according to the third aspect of this application.

[0055] The power consumption device of this application, since it is equipped with a secondary battery provided by this application, has at least the same advantages as the aforementioned secondary battery. [Brief explanation of the drawing]

[0056] To more clearly illustrate the technical concept of the embodiments of this application, the drawings that need to be used in the embodiments of this application are briefly described below. Obviously, the drawings described below represent only a few embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0057] [Figure 1] This is a schematic diagram of a cross-sectional image of the carbon material particles of this application. [Figure 2] This is a schematic diagram of one embodiment of the secondary battery of this application. [Figure 3] This is an exploded schematic diagram of one embodiment of the secondary battery of this application. [Figure 4] This is a schematic diagram of one embodiment of the battery module of this application. [Figure 5] This is a schematic diagram of one embodiment of the battery pack of this application. [Figure 6] Figure 5 is a schematic exploded view of an embodiment of the battery pack shown. [Figure 7] This is a schematic diagram of one embodiment of a power consumption device that includes a secondary battery as a power source according to the present application.

[0058] The drawings are not always drawn to actual scale. The symbols are explained below. 1 Battery pack 2 Upper enclosure 3 Lower enclosure 4 Battery Modules 5 Secondary battery 51 cases 52 Electrode Assembly 53 Lid plate 100 carbon materials 101 External area 102 Internal area [Modes for carrying out the invention]

[0059] The following description will detail embodiments specifically disclosing the carbon material and its manufacturing method, as well as secondary batteries and power consumption devices incorporating the same, with appropriate reference to the drawings. However, unnecessary details may be omitted. For example, detailed descriptions of known matters or redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter described in the claims.

[0060] The “range” disclosed in this application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting one lower limit and one upper limit, the selected lower limit and upper limit limiting the boundary of a particular range. The range thus limited may include or exclude endpoints, and may be any combination, that is, any lower limit may be combined with any upper limit to form a range. For example, if the ranges 60-120 and 80-110 are given for a particular parameter, it is understood that the ranges 60-110 and 80-120 are also expected. Also, if minimum range values ​​1 and 2 and maximum range values ​​3, 4 and 5 are given, the ranges 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5 may all be expected. In this application, unless otherwise stated, the numerical range “a-b” is an abbreviation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" in this specification refers to all real numbers between "0 to 5," and "0 to 5" is an abbreviation for combinations of these numbers. Also, when a parameter is described as an integer greater than or equal to 2 (≧2), it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0061] Unless otherwise specified, all embodiments and optional embodiments of this application may be combined to form new technical concepts. Such technical concepts should be considered to be included in the disclosures of this application.

[0062] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical concepts. Such technical concepts should be considered to be included in the disclosures of this application.

[0063] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but it is preferable that they be performed sequentially. For example, if it is stated that the above method includes steps (a) and (b), it means that the above method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, if it is stated that the above method may further include step (c), it means that step (c) may be added to the above method in any order. For example, the above method may include steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0064] Unless otherwise specified, the terms “equipped with” and “included” in this application mean open or closed. For example, the terms “equipped with” and “included” above may mean “equipped with” or “included” other components not listed, or “equipped with” or “included” only the listed components.

[0065] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following conditions are met: 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).

[0066] Unless otherwise specified, terms used in this application have the common meanings that are ordinarily understood by those skilled in the art.

[0067] Unless otherwise specified, the numerical values ​​of each parameter mentioned in this application can be measured by various test methods commonly used in the art, for example, according to the test methods provided in this application.

[0068] Unless otherwise specified, the term “active ion” in this application refers to an ion capable of reciprocal insertion and removal between the positive and negative electrodes of a secondary battery, and such ions include, but are not limited to, lithium ions.

[0069] In this application, the terms "multiple" and "multiple types" mean two or more.

[0070] Graphite can be classified into artificial graphite and natural graphite depending on the manufacturing process and source. Artificial graphite generally requires a high-temperature graphitization process, which consumes a lot of energy and is therefore costly. Natural graphite, being derived from nature, has the advantage of being relatively inexpensive. It also has the advantage of having a larger capacity.

[0071] Natural graphite mainly consists of flake graphite, natural spheroidal graphite, and microcrystalline graphite. Unlike artificial graphite, natural graphite particles typically have a large number of voids and defects both inside and outside the particles. During the initial charging process of a secondary battery, the electrolyte undergoes numerous side reactions with the particle surface and internal pores, resulting in high initial irreversible capacity loss, low initial Coulomb efficiency, and poor cycle and storage performance. In particular, flake graphite and natural spheroidal graphite have high crystallinity and graphitization, and their microstructure is often layered. This structure causes large volume changes during the desorption and insertion of active ions in natural graphite, which easily leads to the fragmentation of the graphite layered structure and particle fragmentation. After particle fragmentation, the exposed fresh surface continues to react with the electrolyte, further increasing the irreversible capacity loss of the secondary battery.

[0072] Currently, the performance of natural graphite is primarily improved through particle surface coating treatment and / or particle internal filling treatment.

[0073] In particle surface coating treatment, natural graphite and a coating agent (e.g., pitch, polymer compounds, etc.) are uniformly mixed, and then heat-treated to coat the surface of the natural graphite particles with a layer of carbon, slightly repairing defects on the particle surface. However, in the course of research, the inventors of this application have found that the amorphous carbon layer coated on the surface reduces the gram capacity (capacity per gram) and / or compressive density of the natural graphite, affecting the energy density of the secondary battery. At the same time, they have found that even after the amorphous carbon layer is coated on the surface, there are still many defects on the particle surface, and the amorphous carbon layer coated on the surface does not effectively prevent the electrolyte from penetrating the pore structure inside the particles. As a result, the improvement effect on the initial Coulomb efficiency, cycle performance and / or storage performance of the secondary battery is limited.

[0074] In particle internal filling processes, natural graphite is mainly mixed with a filler (e.g., pitch, polymer compounds, etc.), and the filler is packed into the voids inside the particles by methods such as applying a predetermined pressure, vacuuming, and heating, thereby obtaining natural graphite without voids inside the particles. However, in the course of research, the inventors of this application have found that a large amount of carbon, especially soft carbon, packed inside the particles reduces the gram capacity (capacity per gram) of natural graphite, affecting the energy density of the secondary battery. At the same time, because all the voids inside the natural graphite particles are filled with carbon, the volume change that occurs during the desorption and insertion process of active ions in the natural graphite becomes larger, making the particles more easily fragmented. Furthermore, the repeated destruction and reconstruction of the SEI film on the particle surface further increases the irreversible consumption of active ions, increasing the irreversible capacity loss of the secondary battery and shortening its service life. In conventional technology, a layer of amorphous carbon is continuously applied to the surface of natural graphite, which does not have voids inside the particles. This further reduces the gram capacity and / or compressive density of the natural graphite, and because the surface defects of the particles remain numerous, the lifespan of the secondary battery cannot be effectively improved.

[0075] Therefore, after modifying natural graphite by the above-described particle surface coating treatment and / or particle internal filling treatment, it is possible to reduce the irreversible capacity loss of the secondary battery to some extent and improve the initial Coulomb efficiency of the secondary battery. However, the improvement in the initial Coulomb efficiency of the secondary battery is limited, the energy density of the secondary battery is impaired, and the capacity performance characteristics during long-term cycles and storage processes of the secondary battery remain poor.

[0076] In view of this, the inventors of this application, after extensive research, provide a novel carbon material that combines high gram capacity and high initial Coulomb efficiency, and that enables secondary batteries to simultaneously achieve high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0077] Carbon materials

[0078] A first embodiment of the present invention provides a carbon material.

[0079] The carbon material contains a porous structure, and if the amount of carbon material adsorbed by 100g of the carbon material into linseed oil is A, and the specific surface area of ​​the carbon material is B, then the carbon material satisfies 36 ≤ A × B ≤ 75, the unit of the amount of carbon material adsorbed by 100g of the carbon material into linseed oil A is ml, and the unit of the specific surface area B of the carbon material is m 2 It is / g.

[0080] The inventors of this application have discovered, in the course of their research, that when the carbon material satisfies the condition 36 ≤ A × B ≤ 75, secondary batteries can achieve both high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance. The reasons for this are thought to be as follows:

[0081] Firstly, because the surface of the carbon material particles is dense at this time, the carbon material particles have a stable structure, and by avoiding the penetration of the electrolyte into the pore structure inside the carbon material particles as much as possible, the occurrence of side reactions is reduced, the consumption of active ions due to the formation of SEI films inside the particles is reduced, and furthermore, the initial Coulomb efficiency of the carbon material is improved, which can further improve the cycle performance and storage performance of the secondary battery.

[0082] Secondly, because the carbon material particles have fewer surface defects at this stage, their ability to adsorb oily substances is weak, which is advantageous in reducing side reactions in the battery.

[0083] Thirdly, at this time, the carbon material particles can form a rational pore structure in the negative electrode film layer, thereby improving the wettability of the negative electrode sheet to the electrolyte.

[0084] Therefore, the carbon material provided by this application can effectively reduce irreversible capacity loss in secondary batteries, improve the capacity performance characteristics of secondary batteries, and enable secondary batteries to achieve both high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0085] If A × B is less than 36, the amount of carbon material adsorbed onto linseed oil may be small, and / or the specific surface area of ​​the carbon material may be small. When the amount of carbon material adsorbed onto linseed oil is small, the densification of the surface structure of the carbon material is high, which may lead to a large change in the volume of carbon material particles during the desorption and insertion process of active ions. In this case, the particles become more easily fragmented, and the SEI film on the particle surface is more likely to break and rebuild repeatedly, which conversely increases the irreversible consumption of active ions, increases the irreversible capacity loss of the secondary battery, and shortens the lifespan of the secondary battery. When the specific surface area of ​​the carbon material is small, it may be unfavorable for the transport of active ions, thus affecting the capacity, cycle performance, and / or rate performance of the secondary battery.

[0086] When A × B exceeds 75, the amount of carbon material adsorbed onto linseed oil increases, and / or the specific surface area of ​​the carbon material may increase. When the amount of carbon material adsorbed onto linseed oil increases, there are many surface defects and / or pore structures in the carbon material particles, leading to more side reactions in the electrolyte and increased consumption of active ions due to the formation of the SEI film, which reduces the initial Coulomb efficiency of the secondary battery. At the same time, as the number of charge-discharge cycles of the secondary battery increases, the thickness of the SEI film on the surface of the carbon material particles continues to increase, which also affects the cycle performance and / or rate performance of the secondary battery. When the specific surface area of ​​the carbon material increases, the side reaction activity on the surface of the carbon material particles is high, and the consumption of active ions due to the formation of the SEI film increases, which reduces the initial Coulomb efficiency of the secondary battery and affects the storage performance of the secondary battery.

[0087] In some embodiments, 38 ≤ A × B ≤ 65, preferably 38 ≤ A × B ≤ 60, 39 ≤ A × B ≤ 55, 39 ≤ A × B ≤ 52, and 39 ≤ A × B ≤ 50. In further research, the inventors found that this is advantageous for better achieving a high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance in the secondary battery.

[0088] In some examples, the amount A adsorbed by 100g of the carbon material into linseed oil is 30ml to 50mL, preferably 35ml to 47mL. When the amount adsorbed by the carbon material into linseed oil is within the above range, the side reaction activity of the carbon material particle surface is low, which reduces the consumption of active ions due to the formation of the SEI film and avoids the influence on active ion transport caused by an overly dense particle surface. It is also advantageous in forming a rational pore structure between the particles of the negative electrode film layer and improving the wettability of the negative electrode sheet to the electrolyte. As a result, in secondary batteries, a higher initial Coulomb efficiency, high energy density, and good cycle performance and storage performance can be better achieved simultaneously.

[0089] In some embodiments, the specific surface area B of the carbon material is 0.5 m². 2 / g~2.1m 2 The value is / g, preferably 0.7m 2 / g~1.8m 2 / g, 0.9m 2 / g~1.8m 2 / g, 1.0m 2 / g~1.8m 2 / g, 1.0m 2 / g~1.7m 2 / g, 1.0m 2 / g~1.6m 2 The value is / g. When the specific surface area of ​​the carbon material is within the above range, the carbon material has low surface side reaction activity, which reduces the consumption of active ions due to the formation of the SEI film and can improve the initial Coulomb efficiency of the carbon material, while also having high active ion transport performance. As a result, secondary batteries can achieve a better balance of high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance, and can also be given good rate performance.

[0090] The specific surface area of ​​carbon materials has a meaning known in this art and can be measured using instruments and methods known in this art. For example, it can be measured by nitrogen gas adsorption specific surface area analysis, referring to GB / T 19587-2017, and calculated by the BET (Brunauer Emmett Teller) method. As a measuring instrument, the Tri-Star 3020 specific surface area pore size analyzer from Micromeritics, Inc., USA, can be used.

[0091] The amount A adsorbed by 100g of carbon material into linseed oil can be measured according to the following method: Referring to GB / T 3780.2-2017, a test sample dried to a constant mass (e.g., 20g) is weighed, the weighed sample is placed in the mixing chamber of the oil absorber, the temperature of the mixing chamber is 23°C, and it is covered with a lid. The oil outlet of the constant-speed burette is aligned with the opening of the lid of the mixing chamber. The oil absorber is started, the instrument begins to operate and drip linseed oil is dispensed, and as the amount of oil absorbed by the sample increases, the mixture material changes from a free-flowing state to a semi-plastic aggregate, and the viscosity of the mixture constantly increases. This viscosity is transmitted to the torque sensor system of the oil absorber, and when the semi-plastic aggregate reaches a preset torque level due to the dripped oil, the oil absorber and the constant-speed burette automatically close. The value corresponding to 70% of the maximum torque of the fitting curve was read, and the amount A adsorbed by 100g of carbon material into linseed oil was calculated using the formula A = (V / m) × 100, where V represents the volume of linseed oil consumed by the sample corresponding to 70% of the maximum torque, in units of ml, and m represents the mass of the added sample, in units of g.

[0092] In some embodiments, the carbon material has a pore area of ​​0.1 μm². 2 It contains one or more pore structures as described above, preferably with a pore area of ​​0.12 μm². 2 ~2.5μm 2The material includes one or more pore structures. If the carbon material further includes pore structures having the above-mentioned pore area, the pore structures can secure the expansion space necessary for volume changes of the carbon material particles, thereby further reducing the risk of new interfaces being generated due to the fragmentation of the carbon material particles, and consequently reducing the occurrence of side reactions, reducing irreversible capacity loss of the secondary battery, and further improving the cycle performance and storage performance of the secondary battery.

[0093] In some embodiments, the carbon material includes an outer region and an inner region located inside the outer region, wherein the outer region is a region extending 0.25 L from the particle surface of the carbon material into the particle interior, where L is the minor axis length of the carbon material particle, the total pore area of ​​the outer region is S1, the total pore area of ​​the inner region is S2, and S2 > S1.

[0094] In this 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 obtained by measuring a cross-sectional image of the first carbon-based material.

[0095] In this application, the cross-sectional image of the first carbon-based material includes a cross-sectional image passing through the center of the particle of the first carbon-based material. "Particle center" refers to the area within a radius extending 0.1 μm from the geometric center of the particle toward the particle surface.

[0096] In this application, the minor axis length of a particle refers to the minimum value at which a line connecting two points on the surface of the particle passes through the geometric center of the particle.

[0097] Figure 1 is a schematic diagram of a cross-sectional image of a particle of the carbon material 100 of this application, and the cross-sectional image passes through the center of the particle of the carbon material 100. As shown in Figure 1, L represents the length of the minor axis of the particle of the carbon material 100, the region extending 0.25 L from the surface of the particle of the carbon material 100 into the interior of the particle is the outer region 101, and the region inside the outer region 101 is the inner region 102.

[0098] A cross-section of the first carbon-based material can be prepared using a cross-section polisher (e.g., JEOL Ltd.'s IB-09010 CP type argon ion cross-section polisher). Then, referring to JY / T010-1996, the cross-section of the first carbon-based material is scanned using a scanning electron microscope (e.g., ZEISS AG's Sigma 300 scanning electron microscope), 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 are calculated using image processing software (e.g., AVIZO).

[0099] If the carbon material further satisfies S2 > S1, the carbon material particles may have the characteristics of having a large number of pores and / or large pore size in the internal region, but a small number of pores and / or small pore size in the external region. Due to the large number of pores and / or large pore size in the internal region of the carbon material, the pore structure can secure the expansion space necessary for volume changes of the carbon material particles, thereby reducing the risk of new interfaces being generated due to the fragmentation of the carbon material particles, and consequently 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. Due to the small number of pores and / or small pore size in the external region of the carbon material, the carbon material particles can have fewer surface defects and a more stable structure, and the penetration of the electrolyte into the pore structure inside the carbon material particles can be avoided as much as possible, thereby reducing the occurrence of side reactions, reducing the consumption of active ions due to the formation of SEI films inside the particles, and consequently improving the initial Coulomb efficiency of the carbon material, further improving the cycle performance and storage performance of the secondary battery. Therefore, if the carbon material particles further satisfy S2 > S1, it is possible to effectively reduce the irreversible capacity loss of the secondary battery, improve the capacity performance characteristics of the secondary battery, and better achieve a balance between high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance in the secondary battery.

[0100] In some embodiments, the values ​​are 1.3≦S2 / S1≦450, 1.8≦S2 / S1≦400, 2.0≦S2 / S1≦300, 2.5≦S2 / S1≦200, and 3.0≦S2 / S1≦150. After further investigation, the inventors found that by satisfying the above range for S2 / S1, secondary batteries can achieve a better balance of high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0101] In some examples, 0.01 μm 2 ≤S1 ≤ 12.0 μm 2 Preferably, 0.02 μm 2 ≤S1 ≤ 10.0 μm 2 And, 0.02 μm 2 ≤S1 ≤ 8.0 μm 2 And, 0.02 μm 2 ≤S1 ≤ 7.0 μm 2 And, 0.1 μm 2 ≤S1 ≤ 10.0 μm 2 And, 0.1 μm 2 ≤S1 ≤ 7.0 μm 2 Therefore, when the total pore area of ​​the external region of the carbon material is within the above range, the carbon material particles have fewer surface defects and a more stable structure, the penetration of the electrolyte into the pore structure inside the carbon material particles is avoided as much as possible, the occurrence of side reactions is reduced, and the consumption of active ions due to the formation of SEI films inside the carbon material particles is reduced, while not affecting the transport performance of active ions and electrons.

[0102] In some examples, 2.5 μm 2 ≤S2 ≤ 25.0 μm 2 Preferably, 3.0 μm 2 ≤S2 ≤ 22.5 μm 2 And, 3.0 μm 2 ≤S2 ≤ 20.5 μm 2 And, 4.0 μm 2 ≤S2 ≤ 17.5 μm 2Therefore, when the total pore area of ​​the internal region of the carbon material is within the above range, a sufficient and stable expansion space can be secured for the volume change of the carbon material particles, the risk of new interfaces being generated due to the fragmentation of carbon material particles can be reduced, the occurrence of side reactions on the new interface surface can be reduced, and the consumption of active ions due to the formation of SEI films on the new interface surface can be reduced, while the capacity and initial Coulomb efficiency of the carbon material can be improved.

[0103] In some embodiments, L ≥ 4 μm, preferably 4 μm ≤ L ≤ 20 μm, 6 μm ≤ L ≤ 18 μm, 8 μm ≤ L ≤ 18 μm, and 8 μm ≤ L ≤ 16 μm.

[0104] In some embodiments, the area of ​​the pore structure in the external region of the carbon material is 0.2 μm². 2 The following, preferably 0.15 μm 2 The inventors further researched and found that by controlling the area of ​​the pore structure in the external region of the carbon material to within the above range, the external region of the carbon material can have a dense structure, thereby effectively reducing surface defects in the carbon material, improving the structural stability of the carbon material, and minimizing the penetration of the electrolyte into the pore structure inside the carbon material particles, thereby further improving the cycle performance and storage performance of the secondary battery. Of course, this application assumes that the area of ​​all pore structures in the external region of the carbon material is 0.2 μm. 2 This does not limit the scope to the following, but for example, the area of ​​the pore structure is 95% or more, preferably 99% or more, over 0.2 μm². 2 It can be controlled to the following, preferably 0.15 μm 2 The following can be controlled:

[0105] In some embodiments, the internal region of the carbon material has an area of ​​0.15 μm 2 The pore structure contains one or more of the above characteristics, preferably with an area of ​​0.18 μm². 2 ~2.5μm 2The material contains one or more pore structures. In further research, the inventors found that by incorporating pore structures of the above size into the internal region of the carbon material, a sufficient and stable expansion space can be secured for volume changes of the carbon material particles, reducing the risk of fragmentation of the carbon material particles, while improving the compressive density of the carbon material.

[0106] In some embodiments, if the interlayer distance in the outer region of the carbon material is d1 and the interlayer distance in the inner region of the carbon material is d2, then the carbon material satisfies d1 ≥ d2, preferably d1 > d2.

[0107] The large interlayer distance in the outer region of the carbon material is advantageous for the rapid insertion and removal of active ions, thus further improving the dynamic performance of the secondary battery. The small interlayer distance in the inner region of the carbon material is advantageous for improving the gram capacity and compressive density of the carbon material, thus further improving the energy density of the secondary battery.

[0108] In some examples, d1 is between 0.33565 nm and 0.33610 nm.

[0109] In some examples, d2 is between 0.33557 nm and 0.33585 nm.

[0110] The interlayer distances in different regions of carbon material particles can be measured using known instruments and methods in this field. For example, they can be measured using a high-resolution transmission electron microscope (HRTEM). The Thermo Fishers Spectra S / TEM scanning transmission electron microscope can be used as the measuring instrument.

[0111] In some embodiments, the La(110) of the carbon material is 100 nm to 150 nm, preferably 110 nm to 130 nm.

[0112] In some embodiments, the Lc(002) of the carbon material is 20 nm to 45 nm, preferably 28 nm to 40 nm.

[0113] When the La(110) and / or Lc(002) of the carbon material are within an appropriate range, it is advantageous for the carbon material to have high crystallinity and / or degree of graphitization, advantageous for improving the gram capacity of the carbon material, advantageous for improving the active ion and electron transport performance of the negative electrode film layer, and further advantageous for improving the cycle performance, storage performance and / or rate performance of the secondary battery.

[0114] La(110) can represent the crystallite size along the a-axis in the (110) crystal plane of the carbon material, and Lc(002) can represent the crystallite size along the c-axis in the (002) crystal plane of the carbon material, and these can be measured using instruments and methods known in this art. For example, they can be measured using an X-ray diffractometer (e.g., a Bruker D8 Discover), and the measurement can be performed by obtaining the peak intensity and full width at half maximum (FWHM) of the diffraction peak corresponding to the (110) crystal plane and the diffraction peak corresponding to the (002) crystal plane of the carbon material, referring to JIS K0131-1996, JB / T 4220-2011, and then calculating based on Scherrer's formula.

[0115] In some embodiments, the degree of graphitization of the carbon material is 94% to 98%, preferably 95% to 97%. Having the degree of graphitization of the carbon material within this range is advantageous for improving the energy density of the secondary battery, and is also advantageous for improving the cycle performance, storage performance and / or rate performance of the secondary battery.

[0116] The degree of graphitization of carbon materials has a meaning known in the art and can be measured with instruments and methods known in the art. For example, it can be measured using an X-ray diffractometer (e.g., Bruker D8 Discover), and the measurement is performed referring to JIS K 0131-1996, JB / T 4220-2011, by measuring the average interlayer distance d of the (002) crystal plane in the crystal structure of the carbon material.002 Obtain the following equation: g=(0.344-d 002 The degree of graphitization can be calculated based on ) / (0.344-0.3354)×100%. In the above formula, d 002 This is the average interlayer distance of the (002) plane in the crystal structure of a carbon material, expressed in nanometers (nm).

[0117] In some embodiments, the form of the carbon material includes one or more of the following: lumpy, spherical, and substantially spherical. This is advantageous for improving the compressive density of the negative electrode sheet, and consequently, for improving the energy density of the secondary battery.

[0118] In some embodiments, the carbon material contains primary particles, preferably the proportion of primary particles in the carbon material is 50% or more, for example, 55% to 95%, 60% to 100%, 65% to 90%, 65% to 80%, 70% to 100%, 75% to 90%, 80% to 100%, 90% to 100%, or 95% to 100%. The carbon material containing an appropriate proportion of primary particles can have high structural stability, reduce the occurrence of side reactions, improve the compressive density of the negative electrode sheet, and improve the energy density of the secondary battery.

[0119] In some embodiments, the carbon material may consist entirely of primary particles, i.e., the proportion of primary particles in the carbon material is 100%.

[0120] The terms primary and secondary particles are both known in this field. Primary particles are particles in a non-aggregated state. Secondary particles are particles in an aggregated state formed by the aggregation of two or more primary particles. Primary and secondary particles can be distinguished using scanning electron microscope (SEM) images.

[0121] In this application, the proportion of primary particles in a carbon material can be measured by taking any one test sample from the negative electrode film layer, taking any multiple test regions from the test sample, acquiring images of the multiple test regions using a scanning electron microscope, statistically calculating the ratio of the number of carbon material particles in primary particle form to the total number of carbon material particles in each image, and taking the average of the multiple statistical results as the proportion of primary particles in the carbon material.

[0122] In some examples, the volume distribution particle size Dv50 of the carbon material is 8.0 μm to 24.0 μm, preferably 9.5 μm to 22.5 μm.

[0123] In some examples, the volume-distributed particle size Dv10 of the carbon material is 5.0 μm to 15.0 μm, preferably 6.0 μm to 14.0 μm.

[0124] In some examples, the volume distribution particle size Dv90 of the carbon material is 16.0 μm to 35.0 μm, preferably 17.0 μm to 34.0 μm.

[0125] When the volume distribution particle size Dv10, Dv50 and / or Dv90 of the carbon material are within the above range, it is advantageous for improving the transport performance of active ions and electrons, and is also advantageous for forming a rational pore structure between particles in the negative electrode film layer, thereby further improving the cycle performance and / or rate performance of the secondary battery.

[0126] In some embodiments, the (Dv90-Dv10) / Dv50 of the carbon material is 0.55 to 1.55, preferably 0.8 to 1.4. When the (Dv90-Dv10) / Dv50 of the carbon material is within the above range, its particle deposition performance is good, which is advantageous for improving the compressive density of the negative electrode film layer, thereby further improving the energy density of the secondary battery, and is also advantageous for forming a rational pore structure between the particles of the negative electrode film layer.

[0127] The volume distribution particle sizes Dv10, Dv50, and Dv90 of carbon materials have meanings known in this art, representing the particle sizes corresponding to when the cumulative volume distribution percentage of the material reaches 10%, 50%, and 90%, respectively, and can be measured with instruments and methods known in this art. For example, they can be conveniently measured using a laser particle size analyzer, referring to the GB / T 19077-2016 particle size distribution laser diffraction method. The test instrument may be a Mastersizer 2000E laser particle size analyzer from Malvern Instruments Ltd., UK.

[0128] In some embodiments, the tap density of the carbon material is 0.80 g / cm³. 3 ~1.32 g / cm³ 3 The concentration is preferably 0.82 g / cm³. 3 ~1.28 g / cm³ 3 Therefore, if the tap density of the carbon material is within the above range, it is advantageous to improve the compressive density of the negative electrode sheet, further improve the energy density of the secondary battery, form a rational pore structure between the particles of the negative electrode film layer, improve the transport performance of active ions and electrons, and improve the cycle performance and storage performance of the secondary battery.

[0129] The tap density of carbon materials is a known concept in the art and can be measured using instruments and methods known in the art. For example, it can be measured using a powder tap density tester, referring to GB / T 5162-2006. The Dandong Baite BT-301 can be used as the test instrument.

[0130] In some embodiments, the gram capacity of the carbon material is 355 mAh / g to 371 mAh / g, preferably 360 mAh / g to 370 mAh / g. When the gram capacity of the carbon material is within the above range, the energy density of the secondary battery can be improved.

[0131] The gram capacity of carbon materials is known in the art and can be measured by methods known in the art. An exemplary measurement method involves thoroughly mixing a carbon material sample with styrene-butadiene rubber (SBR) as an adhesive, sodium carboxymethylcellulose (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. This slurry is then uniformly applied to the surface of copper foil, which serves as the negative electrode current collector, and dried in an oven as needed. Ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio of 1:1:1 to obtain an organic solvent. LiPF6 is then dissolved in the organic solvent to prepare an electrolyte with a concentration of 1 mol / L. Subsequently, a CR2430 type button cell is assembled using a metallic lithium sheet as the counter electrode and a polyethylene (PE) film as the separator in a box protected by argon gas. At 25°C, the button cell manufactured above was first discharged with a constant current of 0.15mA to 0.005V, left to stand for 5 minutes, and then discharged again with a constant current of 10μA to 0.005V to record the initial discharge capacity of the button cell. Subsequently, it was charged with a constant current of 0.3mA to 2.0V to record the charge capacity of the button cell. The ratio of the charge capacity of the button cell to the mass of the carbon material sample is the gram capacity of the carbon material.

[0132] Manufacturing method

[0133] A second embodiment of the present application provides a method for manufacturing a carbon material that can produce the carbon material of the first embodiment of the present application.

[0134] The method for producing the carbon material includes: step 1 supplying a raw material having a plurality of pore structures; step 2 uniformly mixing the raw material and a filler in a predetermined ratio, and then maintaining the mixture at a first temperature T1 for a first time t1 to obtain an intermediate; and step 3 maintaining the obtained intermediate at a second temperature T2 for a second time t2 to obtain a carbon material, wherein the carbon material contains pore structures, and if the amount of adsorption of 100g of the carbon material into linseed oil is A, and the specific surface area of ​​the carbon material is B, then the carbon material satisfies 36 ≤ A × B ≤ 75, the unit of the amount of adsorption A of 100g of the carbon material into linseed oil is ml, and the unit of the specific surface area B of the carbon material is m 2 It is / g.

[0135] In some embodiments, the raw materials for producing the carbon material include natural graphite. Preferably, the natural graphite includes one or more of flake graphite, natural spheroidal graphite, and microcrystalline graphite, and preferably natural spheroidal graphite.

[0136] "Natural spheroidal graphite" refers to natural graphite that is spherical or nearly spherical, and does not mean that all natural graphite particles are controlled to be ideal spheres. In some examples, natural spheroidal graphite of a desired particle size and shape can be obtained by pre-treating flake graphite, and preferably, the pre-treatment includes steps such as crushing, classification, spheroidization, and purification.

[0137] In some embodiments, the form of the raw material includes one or more types of spherical and substantially spherical shapes.

[0138] In some examples, the volume distribution particle size Dv50 of the raw material is 8.5 μm to 24.0 μm, preferably 10.5 μm to 22.5 μm.

[0139] By adjusting the particle size of the raw materials within the above range, the aggregation of the raw materials in subsequent manufacturing processes can be reduced, thereby reducing problems such as an increase in surface defects in carbon material particles and an increase in surface side reaction sites, which would otherwise be necessary due to the need to increase the depolymerization step.

[0140] In some examples, the ash content in the raw material is 1 wt% or less. A low ash content in the raw material is advantageous for the carbon material to have fewer surface defects.

[0141] In some embodiments, the softening point temperature of the filler is 110°C to 175°C. For example, the softening point temperature of the filler may be in the range of 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, or any other value above that. Preferably, the softening point temperature of the filler is 120°C to 170°C.

[0142] In the course of research, the inventors found that when the softening point temperature of the filler is within the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping the A×B of the carbon material within an appropriate range, advantageous for adjusting the size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and advantageous for adjusting S2 / S1 within an appropriate range. Furthermore, the following situation can be avoided: If the softening point temperature of the filler is too high, the filler becomes difficult to flow and fill into the pore structure of the raw material, thereby preventing the effective reduction of surface and internal defects in the obtained carbon material particles, and also preventing the electrolyte from effectively penetrating the pore structure inside the obtained carbon material particles. In this case, the adsorption amount A to linseed oil of the carbon material and / or the specific surface area B of the carbon material easily increase, and the A×B of the carbon material easily increases, further affecting the initial Coulomb efficiency, cycle performance, and storage performance of the secondary battery. If the softening point temperature of the filler is too low, the filler contains a relatively large amount of small molecules, and these small molecules are easily volatilized by heat, so the filler is easily fluidized and filled into the pore structure of the raw material. However, when heat-treated at high temperatures, the small molecules in the filler volatilize, and as a result, the remaining carbon is not effectively filled into the pore structure of the raw material, and an effective filling effect cannot be achieved, or the carbon that actually remains in the filled area has a relatively large number of pore structures. In this case, there are many surface defects in the carbon material particles, and the amount of carbon material adsorbed into linseed oil A and / or the specific surface area B of the carbon material easily increases, and the A×B of the carbon material easily increases. Furthermore, the consumption of active ions due to the formation of the SEI film and the irreversible capacity loss of the secondary battery cannot be reduced, and at the same time the cycle performance and storage performance of the secondary battery are affected.

[0143] In some embodiments, the caulking value of the filler is 26% to 50%, preferably 33% to 45%. In the course of research, the inventors found that when the caulking value of the filler is within the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping A×B of the carbon material within an appropriate range, advantageous for adjusting the size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and also advantageous for adjusting S2 / S1 within an appropriate range.

[0144] The caulking value of the filler has a meaning known in the art and can be measured using instruments and methods known in the art. For example, it can be measured by referring to GB / T 8727-2008.

[0145] In some embodiments, the softening point temperature of the filler is 120°C to 170°C, and the caulking value is 33% to 45%.

[0146] In some embodiments, the volume distribution particle size Dv50 of the filler is 6 μm or less, preferably 1 μm to 6 μm, 1 μm to 5 μm, 2 μm to 5 μm, or 3 μm to 5 μm. This is advantageous for the filler to fill the pore structure of the raw material after melting due to heat, and is also advantageous for improving the uniformity of the dispersion between the filler and the raw material.

[0147] In some embodiments, the content of quinoline insoluble matter in the filler is 1 wt% or less, preferably 0.8 wt% or less. A high content of quinoline insoluble matter affects the actual atomic arrangement of residual carbon in the filled area, which in turn affects the powder compression density of the carbon material and the energy density of the secondary battery.

[0148] In some embodiments, the filler includes one or more of coal pitch and petroleum pitch.

[0149] In some embodiments, the mass ratio of the filler to the raw material is (10-32):100, preferably (10-25):100, (11-22):100, or (11-20):100. This is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, for keeping the A×B of the carbon material within an appropriate range, for adjusting the pore size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and for adjusting S2 / S1 within an appropriate range. Furthermore, the following situations can be avoided. If the mass ratio of the filler to the raw material is too small, the filler will not flow into the pore structure of the raw material effectively, thereby preventing an effective reduction in internal defects in the resulting carbon material particles and an inability to effectively prevent the electrolyte from penetrating the pore structure inside the resulting carbon material particles. In this case, the amount of carbon material adsorbed by linseed oil A and / or the specific surface area of ​​the carbon material B will easily increase, and the A×B of the carbon material will easily increase, further affecting the initial Coulomb efficiency, cycle performance, and storage performance of the secondary battery. If the mass ratio of the filler to the raw material is too large, the pore structure inside the raw material will easily be completely filled. In this case, the amount of carbon material adsorbed by linseed oil A and / or the specific surface area of ​​the carbon material B will easily decrease, and the A×B of the carbon material will easily decrease. As a result, the volume change that occurs during the desorption and insertion process of active ions in the resulting carbon material will increase, making the particles more easily crushed. Furthermore, the consumption of active ions due to the formation of the SEI film will increase, and the irreversible capacity loss of the secondary battery will increase. Furthermore, if the mass ratio of filler to raw material is too high, a large amount of filler remains on the particle surface. In this case, the particles become more prone to aggregation, which not only increases the depolymerization process but also reduces the gram volume and compressive density of the resulting carbon material.

[0150] By adjusting one or more parameters such as the type of filler, softening point, coking value, and amount added to the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping the A×B of the carbon material within an appropriate range, advantageous for adjusting the pore size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and advantageous for adjusting S2 / S1 within an appropriate range. Furthermore, after the filler is melted by heat, it does not have high viscosity and maintains good fluidity, and the raw material particles do not adhere easily, reducing aggregation of the raw material particles in subsequent manufacturing processes. This reduces problems such as an increase in surface defects and an increase in surface side reaction sites in the resulting carbon material particles, which would otherwise require an increase in the depolymerization step.

[0151] In some embodiments, the heating process in step 2, in which the raw materials and the filler are uniformly mixed in a predetermined ratio and then heated to a first temperature T1, is a stepwise heating process, and preferably includes a first heating process, a second heating process, and a third heating process.

[0152] In some embodiments, the first heating process involves raising the temperature to 200°C to 250°C and maintaining the temperature for 0.5 to 2 hours.

[0153] In the course of research, the inventors found that when the holding time of the first heating process is within the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping the A×B of the carbon material within an appropriate range, advantageous for adjusting the size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and advantageous for adjusting S2 / S1 within an appropriate range. Furthermore, the following situation can be avoided: If the holding time is too short, the filler is not easily fluidized and filled into the pore structure of the raw material, and carbonization may occur on the particle surface, so the internal defects of the obtained carbon material particles cannot be effectively reduced, and the electrolyte cannot be effectively prevented from penetrating the pore structure inside the obtained carbon material particles. In this case, the adsorption amount A to linseed oil of the carbon material and / or the specific surface area B of the carbon material can easily become large, the A×B of the carbon material can easily become large, and further affect the initial Coulomb efficiency, cycle performance and storage performance of the secondary battery. If the heat retention time is too long, the filler material is more likely to flow and fill all the pore structures of the raw material, and the amount of carbon material adsorbed by linseed oil A and / or the specific surface area B of the carbon material will easily decrease, and the A × B of the carbon material will easily decrease. As a result, the volume change that occurs during the desorption and insertion process of active ions in the carbon material will increase, the particles will be more easily crushed, the consumption of active ions due to the formation of the SEI film will increase, the irreversible capacity loss of the secondary battery will increase, and the cycle performance, storage performance and rate performance of the secondary battery will also be affected.

[0154] In some embodiments, the second heating process involves raising the temperature to 450°C to 550°C and maintaining the temperature at that level for 0.5 to 2 hours.

[0155] In some embodiments, the third heating process raises the temperature to the first temperature T1 and maintains that temperature for a first time t1.

[0156] In the stepwise heating process, the temperature is first raised to 200°C to 250°C. Since the heating temperature is higher than the softening point of the filler, the filler melts and softens due to the heat, and can be allowed to flow and fill the pore structure of the raw material by being kept warm for 0.5 to 2 hours. Subsequently, the temperature is raised to 450°C to -550°C. At this point, the molten and softened filler undergoes a carbonization reaction, gradually becoming a semi-focal state and turning into a viscous liquid or solid. This prevents the filler from entering all of the pore structures of the raw material. Finally, the temperature is raised to the first temperature T1, at which point the filler undergoes a carbonization reaction, thereby effectively filling the pore structure occupied by the filler, reducing surface defects, and is also advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, is advantageous for keeping A×B of the carbon material within an appropriate range, is advantageous for adjusting the size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and is also advantageous for adjusting S2 / S1 within an appropriate range.

[0157] In some embodiments, in step 2, the temperature is raised to the first temperature T1 at a rate of 1°C / min to 10°C / min. For example, the heating rate may be in the range of 1.5°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 value above. Preferably, the heating rate is 1.5°C / min to 8°C / min.

[0158] In some embodiments, the heating rate of the first heating process may be 1°C / min to 10°C / min, and preferably 1.5°C / min to 8°C / min.

[0159] In the course of research, the inventors found that when the heating rate of the first heating process is within the above range, it is advantageous to adjust the size and / or number of pores in the external and internal regions of the carbon material to an appropriate range, thereby adjusting S2 / S1 to an appropriate range. Furthermore, the following situations can be avoided: If the heating rate is too high, the filler may carbonize on the surface of the raw material particles, making it difficult for the filler to flow and fill the pore structure of the raw material. This prevents an effective reduction in internal defects in the resulting carbon material particles, and prevents the electrolyte from effectively penetrating the internal pore structure of the resulting carbon material particles, ultimately affecting the initial Coulomb efficiency, cycle performance, and storage performance of the secondary battery. If the heating rate is too low, the filler is more likely to flow and fill all the pore structures of the raw material. This increases the volume change that occurs during the desorption and insertion process of active ions in the carbon material, making the particles more easily fragmented. This increases the consumption of active ions due to the formation of the SEI film, increases the uncapacitated loss of the secondary battery, and affects the cycle performance, storage performance, and rate performance of the secondary battery.

[0160] In some embodiments, the heating rate of the second heating process may be 1°C / min to 10°C / min, and preferably 1.5°C / min to 8°C / min.

[0161] In some embodiments, the heating rate of the third heating process may be 1°C / min to 10°C / min, and preferably 1.5°C / min to 8°C / min.

[0162] In some embodiments, in step 2, the first temperature T1 is between 700°C and 1100°C. For example, the first temperature T1 may be in the range of any number such as 750°C, 800°C, 850°C, 900°C, 950°C, 1000°C, 1050°C, 1100°C or higher. Preferably, the first temperature T1 is between 750°C and 1100°C.

[0163] In the course of research, the inventors found that when the first temperature is within the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping the A×B of the carbon material within an appropriate range, advantageous for adjusting the pore size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and advantageous for adjusting S2 / S1 within an appropriate range. Furthermore, the following situations can be avoided: If the first temperature is too low, the filler material may not be completely converted into carbon material, and as it continues to decompose into small molecular substances during subsequent heat treatment, the carbon that actually remains in the filler region will have a large number of pore structures, and will not be able to effectively reduce the internal defects of the obtained carbon material particles, nor will it be able to effectively prevent the electrolyte from penetrating the internal pore structures of the obtained carbon material particles, and at the same time the surface defects of the obtained carbon material will increase, the adsorption amount A to linseed oil and / or the specific surface area B of the carbon material will easily increase, the A×B of the carbon material will easily increase, and further affect the initial Coulomb efficiency, cycle performance and storage performance of the secondary battery. Firstly, if the temperature is too high, energy consumption and costs in the manufacturing process of carbon materials increase.

[0164] In some embodiments, the first time t1 is between 0.5h and 5h. For example, the first time t1 may be in the range of 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, or any other number above. Preferably, the first time t1 is between 0.5h and 3h.

[0165] In the course of research, the inventors found that when the first time is within the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping the A×B of the carbon material within an appropriate range, advantageous for adjusting the pore size and / or number of pores in the external and internal regions of the carbon material within an appropriate range, and advantageous for adjusting S2 / S1 within an appropriate range. Furthermore, the following situation can be avoided: If the first time is too short, the filler material may not be completely converted into carbon material, and as it continues to decompose into small molecular substances during subsequent heat treatment, the carbon that actually remains in the filler region will have a large number of pore structures, and will not be able to effectively reduce the internal defects of the obtained carbon material particles, nor will it be able to effectively prevent the electrolyte from penetrating the internal pore structures of the obtained carbon material particles, and at the same time the surface defects of the obtained carbon material will increase, the adsorption amount A to linseed oil and / or the specific surface area B of the carbon material will easily increase, the A×B of the carbon material will easily increase, and further affect the initial Coulomb efficiency, cycle performance and storage performance of the secondary battery. If the first time is too long, energy consumption and costs in the manufacturing process of carbon materials tend to increase.

[0166] In some embodiments, the heat treatment in step 2 may be carried out in an intermediate frequency furnace, a roller hearth kiln, a rotary kiln, or a pusher kiln.

[0167] In some embodiments, the heat treatment atmosphere in step 2 may be a protective gas atmosphere. The protective gas may include one or more of nitrogen, argon, and helium.

[0168] In step 2, adjusting one or more of the heating rate, first temperature, first time, heating process, etc., within the above range is advantageous for producing the desired carbon material, for example, that the carbon material has an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, that A×B of the carbon material be within an appropriate range, that the pore size and / or number of pores in the external and internal regions of the carbon material be within an appropriate range, and that S2 / S1 be within an appropriate range.

[0169] In some embodiments, the second temperature T2 is 1920°C to 2520°C, and may be in the range of any number such as 1950°C, 2000°C, 2050°C, 2100°C, 2150°C, 2200°C, 2250°C, 2300°C, 2350°C, 2400°C, 2450°C, 2500°C or higher. Preferably, the second temperature T2 is 2050°C to 2400°C.

[0170] In the course of research, the inventors found that when the second temperature is within the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping the A×B of the carbon material within an appropriate range, and advantageous for the carbon material to have low surface defects, high gram capacity and / or high compressive density. Furthermore, the following situations can be avoided: If the second temperature is too low, the resulting carbon material particles have many surface defects, in which case the adsorption amount A to linseed oil and / or the specific surface area B of the carbon material easily become large, the A×B of the carbon material also easily becomes large, and further affects the initial Coulomb efficiency, cycle performance and storage performance of the secondary battery. If the second temperature is too high, the content of disordered carbon in the resulting carbon material is too low, and both the crystallinity and graphitization of the carbon material are high, in which case it is disadvantageous for the rapid desorption and insertion of active ions, and the volume change of the carbon material during the charge-discharge process is large, which increases the risk of carbon material particle fragmentation and thus affects the cycle performance and / or dynamic performance of the secondary battery. Furthermore, if the second temperature is too high, energy consumption and costs in the manufacturing process of carbon materials will increase.

[0171] In some embodiments, the second time t2 is between 1h and 6h. For example, the second time t1 may be in the range of 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, or any of these values. Preferably, the second time t2 is between 2h and 6h.

[0172] In the course of research, the inventors found that when the second time is within the above range, it is advantageous for the carbon material to have an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, advantageous for keeping the A×B of the carbon material within an appropriate range, and advantageous for the carbon material to have low surface defects, high gram capacity and / or high compressible density. Furthermore, the following situations can be avoided: If the second time is too short, the resulting carbon material particles have many surface defects, in which case the adsorption amount A to linseed oil and / or the specific surface area B of the carbon material easily become large, the A×B of the carbon material also easily becomes large, and further affects the initial Coulomb efficiency, cycle performance and storage performance of the secondary battery. If the second time is too long, the content of disordered carbon in the resulting carbon material is too low, and both the crystallinity and graphitization of the carbon material are high, in which case it is disadvantageous for the rapid desorption and insertion of active ions, and the volume change of the carbon material during the charge-discharge process is large, which increases the risk of carbon material particle fragmentation and thus affects the cycle performance and / or dynamic performance of the secondary battery. Furthermore, if the second time is too long, energy consumption and costs in the manufacturing process of carbon materials will increase.

[0173] In some embodiments, in step 3, the heat treatment can be carried out in an intermediate frequency furnace, a box-type graphitizing furnace, an Acheson-type graphitizing furnace, a continuous graphitizing furnace, or an in-line graphitizing furnace.

[0174] In some embodiments, in step 3, the intermediate frequency furnace and the continuous graphitization heat treatment atmosphere may be a protective gas atmosphere. The protective gas may include one or more of nitrogen, argon, and helium.

[0175] By adjusting one or more of the second temperature and second time within the above range, it is advantageous to reduce the content of irregular carbon in the carbon material, to ensure that the carbon material has an appropriate adsorption amount A to linseed oil and / or an appropriate specific surface area B, and to keep the A × B of the carbon material within an appropriate range.

[0176] The carbon material manufacturing method described in this application is simple, highly safe, does not require pre-setting pressure or vacuum treatment, and does not require an additional depolymerization step in the heat treatment process. The carbon material manufactured in this application has low volume expansion, high structural stability, and few surface defects, so it can combine high gram capacity and high initial Coulomb efficiency, and can also achieve high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance in secondary batteries.

[0177] The manufacturing method described in this application is low-cost, highly practical, and suitable for large-scale production.

[0178] secondary battery

[0179] A third embodiment of the present application provides a secondary battery.

[0180] This application does not particularly limit the type of secondary battery; for example, the secondary battery may be a lithium-ion battery. Typically, a secondary battery includes a positive electrode sheet, a negative electrode sheet, and an electrolyte. During the charging and discharging process of the secondary battery, active ions reciprocate between the positive electrode sheet and the negative electrode sheet for insertion and removal, and the electrolyte plays a role in conducting the active ions between the positive electrode sheet and the negative electrode sheet. This application does not particularly limit the type of electrolyte, and it can be selected according to actual needs. For example, the electrolyte may be at least one selected from solid electrolytes and liquid electrolytes (i.e., electrolyte solution). A secondary battery using an electrolyte solution, and a secondary battery using some solid electrolytes, may further include a separator provided between the positive electrode sheet and the negative electrode sheet to serve as an isolation.

[0181] [Negative electrode sheet]

[0182] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode film layer provided on at least one surface of the negative electrode current collector. For example, the negative electrode current collector has two opposing surfaces in its thickness direction, and the negative electrode film layer is provided on one or both of the two opposing surfaces of the negative electrode current collector.

[0183] In some embodiments, the negative electrode film layer includes a carbon material according to the first embodiment of this application or a carbon material manufactured by the method described in the second embodiment of this application. This enables secondary batteries to achieve both high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance.

[0184] In some embodiments, the negative electrode film layer may further contain other negative electrode active materials besides the carbon material described above. In some embodiments, the other negative electrode active materials include, but are not limited to, one or more of conventional 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.

[0185] In some embodiments, the negative electrode film layer may optionally contain a negative electrode conductive agent. The type of negative electrode conductive agent is not particularly limited in this application, and examples include one or more of superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0186] In some embodiments, the negative electrode film layer may optionally contain a negative electrode binder. This application does not particularly limit the type of negative electrode binder, and as an example, the negative electrode binder may contain one or more of the following: styrene-butadiene rubber (SBR), water-soluble unsaturated resin SR-1B, aqueous acrylic resin (e.g., polyacrylate PAA, polymethacrylate PMAA, sodium polyacrylate PAAS), polyacrylamide (PAM), polyvinyl alcohol (PVA), sodium alginate (SA), and carboxymethyl chitosan (CMCS).

[0187] In some embodiments, the negative electrode film layer may contain other additives as needed. For example, the other additives may include thickeners such as sodium carboxymethylcellulose (CMC), PTC thermistor material, etc.

[0188] In some embodiments, the negative electrode current collector can be a metal foil sheet or a composite current collector. Copper foil can be used as an example of a metal foil sheet. The composite current collector can include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. For example, the metal material may include one or more of copper, copper alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer material substrate may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0189] The negative electrode film layer is typically formed by applying a negative electrode slurry to a negative electrode current collector, drying it, and cold pressing it. The negative electrode slurry is typically formed by dispersing a negative electrode active material, a selectable conductive agent, a selectable binder, and other selectable auxiliary agents in a solvent and stirring them uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP) or deionized water.

[0190] The negative electrode sheet does not exclude any additional functional layers other than the negative electrode film layer. For example, in some embodiments, the negative electrode sheet according to this application further includes a conductive undercoat layer (e.g., consisting of a conductive agent and an adhesive) sandwiched between the negative electrode current collector and the negative electrode film layer and provided on the surface of the negative electrode current collector, and in some embodiments, the negative electrode sheet according to this application further includes a protective layer covering the surface of the negative electrode film layer.

[0191] [Positive electrode sheet]

[0192] In some embodiments, the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer provided on at least one surface of the positive electrode current collector. For example, the positive electrode current collector has two opposing surfaces in its thickness direction, and the positive electrode film layer is provided on one or both of the two opposing surfaces of the positive electrode current collector.

[0193] The positive electrode current collector can be a metal foil sheet or a composite current collector. An example of a metal foil sheet is aluminum foil. The composite current collector may include a polymer material substrate and a metal material layer formed on at least one surface of the polymer material substrate. For example, the metal material may include one or more of aluminum, aluminum alloys, nickel, nickel alloys, titanium, titanium alloys, silver, and silver alloys. For example, the polymer material substrate may include one or more of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), and polyethylene (PE).

[0194] The positive electrode film layer typically comprises a positive electrode active material, a selectable adhesive, and a selectable conductive agent. The positive electrode film layer is typically formed by applying a positive electrode slurry to the positive electrode current collector, drying, and cold pressing. The positive electrode slurry is typically formed by dispersing the positive electrode active material, a selectable conductive agent, a selectable adhesive, and any other components in a solvent and stirring uniformly. The solvent may, but is not limited to, N-methylpyrrolidone (NMP). The adhesive used for the positive electrode film layer typically comprises one or more of the following: polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-tetrafluoroethylene-propylene terpolymer, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene terpolymer, tetrafluoroethylene-hexafluoropropylene copolymer, and fluorine-containing acrylate resin. For example, the conductive agent used in the positive electrode film layer includes one or more of the following: superconducting carbon, conductive graphite, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers.

[0195] The positive electrode active material can be a positive electrode active material for secondary batteries that is known in the field.

[0196] When the secondary battery of the present application is a lithium ion battery, the positive electrode active material includes, but is not limited to, one or more of lithium-containing transition metal oxides, lithium-containing phosphates, and their modified compounds. Examples of the lithium transition metal oxides include, but are not limited to, one or more of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel cobalt oxide, lithium manganese cobalt oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and their modified compounds. Examples of the lithium-containing phosphates include, but are not limited to, one or more of lithium iron phosphate, a composite material of lithium iron phosphate and carbon, lithium manganese phosphate, a composite material of lithium manganese phosphate and carbon, lithium manganese iron phosphate, a composite material of lithium manganese iron phosphate and carbon, and their modified compounds.

[0197] In some embodiments, in order to further improve the energy density of the secondary battery, the positive electrode active material used in the lithium ion battery may include one or more of lithium transition metal oxides and their modified compounds having the general formula Li a Ni b Co c M d O e A f where 0.8 ≦ a ≦ 1.2, 0.5 ≦ b < 1, 0 < c < 1, 0 < d < 1, 1 ≦ e ≦ 2, 0 ≦ f ≦ 1, M is one or more selected from Mn, Al, Zr, Zn, Cu, Cr, Mg, Fe, V, Ti, and B, and A is one or more selected from N, F, S, and Cl.

[0198] In some embodiments, for example, the positive electrode active material for the lithium ion battery is LiCoO2, LiNiO2, LiMnO2, LiMn2O4, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2 (NCM333), LiNi 0.5 Co 0.2 Mn 0.3 O2 (NCM523), LiNi0.6 Co 0.2 Mn 0.2 O2 (NCM622), LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811), LiNi 0.85 Co 0.15 Al 0.05 It may contain one or more of O2, LiFePO4, and LiMnPO4.

[0199] In this application, the modified compound of each of the above cathode active materials can be subjected to doping modification and / or surface coating modification with respect to the cathode active material.

[0200] [Electrolyte]

[0201] In some embodiments, the electrolyte uses an electrolytic solution containing an electrolyte salt and a solvent.

[0202] The type of the electrolyte salt is not specifically limited and can be selected according to actual needs.

[0203] When the secondary battery of this application is a lithium-ion battery, for example, the electrolyte salt includes one or more of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium trifluoromethanesulfonate (LiTFS), lithium difluorooxalate borate (LiDFOB), lithium bis(oxalate)borate (LiBOB), lithium difluorophosphate (LiPO2F2), lithium difluorodioxalate phosphate (LiDFOP), and lithium tetrafluorosulfate phosphate (LiTFOP).

[0204] The type of solvent is not specifically limited and can be selected according to actual needs. In some embodiments, the solvent may, for example, include one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate (MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS), and diethyl sulfone (ESE).

[0205] In some embodiments, the electrolyte may contain additives as needed. For example, the additives may include negative electrode film-forming additives, positive electrode film-forming additives, and additives that can improve certain performance characteristics of the secondary battery, such as additives that improve the overcharge performance of the secondary battery, additives that improve the high-temperature performance of the secondary battery, and additives that improve the low-temperature output performance of the secondary battery.

[0206] [Separator]

[0207] In this application, the type of separator is not particularly limited, and any known porous structure separator having good chemical and mechanical stability can be selected.

[0208] In some embodiments, the material of the separator may include one or more of the following: glass fiber, nonwoven fabric, polyethylene, polypropylene, and polyvinylidene fluoride. The separator may be a single-layer film or a multilayer composite film. If the separator is a multilayer composite film, the materials of each layer may be the same or different.

[0209] In some embodiments, the positive electrode sheet, the separator, and the negative electrode sheet can be manufactured into an electrode assembly by a winding process or a lamination process.

[0210] In some embodiments, the secondary battery may include an outer casing. This casing is used to seal the electrode assembly and electrolyte.

[0211] In some embodiments, the outer packaging may be a rigid case such as a hard plastic case, an aluminum case, or a steel case. The outer packaging may also be a soft pack, for example, a soft bag. The material of the soft bag may be one or more of the following plastics: polypropylene (PP), polybutylene terephthalate (PBT), and polybutylene succinate (PBS).

[0212] In this application, the shape of the secondary battery is not particularly limited and may be cylindrical, rectangular, or any other shape. Figure 2 shows a rectangular secondary battery 5 as an example.

[0213] In some embodiments, as shown in Figure 3, the exterior may include a case 51 and a cover plate 53. The case 51 includes a bottom plate and side plates connected to the bottom plate, and the bottom plate and side plates surround and form a housing cavity. The case 51 has an opening that communicates with the housing cavity, and the cover plate 53 covers the opening and closes the housing cavity. The positive electrode sheet, negative electrode sheet and separator can be formed into an electrode assembly 52 by a winding process or a lamination process. The electrode assembly 52 is packaged in the housing cavity. The 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 can be adjusted as needed.

[0214] The method for manufacturing a secondary battery described in this 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, separator, and negative electrode sheet can be formed as an electrode assembly by a winding process or a lamination process, the electrode assembly can be placed in an outer casing, the electrolyte can be injected after drying, and a secondary battery can be obtained through processes such as vacuum sealing, standing, chemical formation, and shaping.

[0215] In some embodiments of this application, the secondary battery according to this 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.

[0216] Figure 4 is a schematic diagram of an example battery module 4. As shown in Figure 4, in the battery module 4, the multiple secondary batteries 5 may be arranged sequentially along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, these multiple secondary batteries 5 may be fixed together with fasteners.

[0217] Alternatively, the battery module 4 may further include a housing having a housing space for accommodating multiple secondary batteries 5.

[0218] In some embodiments, the battery modules may be assembled into a battery pack, and the number of battery modules included in the battery pack can be adjusted according to the application and capacity of the battery pack.

[0219] Figures 5 and 6 are schematic diagrams of an example battery pack 1. As shown in Figures 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, the upper housing 2 covering the lower housing 3 and forming a sealed space for housing the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any manner.

[0220] power consumption equipment

[0221] This application further provides a power consumption device comprising at least one of the secondary battery, battery module, or battery pack of this application. The secondary battery, battery module, or battery pack may be used as a power source for the power consumption device, or as an energy storage unit for the power consumption device. The power consumption device may be, but is not limited to, mobile devices (e.g., mobile phones, tablet computers, laptop computers, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.

[0222] The aforementioned power consumption device can be configured to use a secondary battery, battery module, or battery pack, depending on its usage needs.

[0223] Figure 7 is a schematic diagram of an example power consumption device. This power consumption device is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle, etc. To meet the requirements for high power output and high energy density of this power consumption device, a battery pack or battery module can be used.

[0224] Other examples of power-consuming devices may include mobile phones, tablet computers, and laptop computers. These power-consuming devices are generally required to be thin and can use rechargeable batteries as a power source.

[0225] Examples

[0226] The following examples are intended to illustrate the disclosures of this application in more detail, and are merely interpretive in nature, as it will be obvious to those skilled in the art that various modifications and changes can be made within the scope of the disclosures of this application. Unless otherwise specified, all parts, percentages, and ratios described in the following examples are based on mass, all reagents used in the examples are commercially available or can be synthesized according to conventional methods and used directly without requiring further processing, and the equipment used in the examples is commercially available.

[0227] Example 1

[0228] (1) Manufacturing of carbon materials

[0229] In Step 1, 100-mesh flake graphite was subjected to mechanical grinding, classification, spheroidization, and purification to obtain natural spheroidal graphite with a volume distribution particle size Dv50 of 17 μm and an ash content of 0.01%.

[0230] In Step 2, the obtained natural spheroidal graphite and petroleum pitch (softening point temperature of 120°C, volume distribution particle size Dv50 of 4.3 μm, and coking value of 33%) were mixed in a VC mixer for 30 minutes in a mass ratio of 100:15. The mixed material was then placed in a roller hearth kiln and heated to 230°C at a rate of 5°C / min and held for 1 hour (first heating process). Subsequently, the temperature was raised to 500°C at a rate of 5°C / min and held for 1 hour (second heating process), and then further raised to 1100°C at a rate of 5°C / min and held for 1 hour (third heating process). After completion, the material was cooled to room temperature to obtain an intermediate.

[0231] In step 3, the obtained intermediate was placed in an Acheson graphitization furnace, heated to 2300°C and maintained for 2 hours. After completion, it was demagnetized and sieved to obtain the carbon material.

[0232] (2) Manufacturing of button batteries (half-cells)

[0233] The carbon material produced above, along with styrene-butadiene rubber (SBR) as an adhesive, sodium carboxymethylcellulose (CMC) as a thickener, and carbon black as a conductive agent, were thoroughly mixed with an appropriate amount of deionized water as a solvent in a mass ratio of 96.2:1.8:1.2:0.8 to form a uniform negative electrode slurry. The negative electrode slurry was uniformly applied to the surface of the copper foil, which served as the negative electrode current collector, and dried in an oven for further preparation. Ethylene carbonate (EC), ethyl methyl 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 produce an electrolyte with a concentration of 1 mol / L. Subsequently, a CR2430 type button cell was assembled in a glove box protected by argon gas, using a metallic lithium sheet as the counter electrode and a polyethylene (PE) thin film as the separator.

[0234] (3) Manufacturing of secondary batteries (full cells)

[0235] The carbon material produced above, the conductive agent carbon black (Super P), the adhesive styrene-butadiene rubber, and the thickener sodium carboxymethylcellulose were thoroughly mixed in a suitable amount of deionized water as a solvent in a weight ratio of 96:1:1:2 to form a negative electrode slurry. The negative electrode slurry was applied to two surfaces of copper foil, which served as the negative electrode current collector, and after drying and cold pressing, a negative electrode sheet was obtained.

[0236] LiFePO4, conductive carbon black, and polyvinylidene fluoride were mixed in a weight ratio of 96:2.5:1.5, an appropriate amount of solvent NMP was added, and the mixture was uniformly stirred to obtain a positive electrode slurry. The positive electrode slurry was applied to two surfaces of a positive electrode current collector aluminum foil, dried, and cold-pressed to obtain a positive electrode sheet.

[0237] A 12 μm thick polypropylene film was used as a separator, and the positive electrode sheet and negative electrode sheet manufactured above were arranged in order. The separator was positioned between the positive and negative electrode sheets to provide isolation, and then wound up to obtain an electrode assembly. The electrode assembly was placed in an outer casing, dried, and then injected with the same electrolyte as the button battery manufactured above. After vacuum sealing, standing, chemical conversion, and capacitance processing, a secondary battery was obtained.

[0238] Comparative Example 1

[0239] The method for manufacturing half-cells and full-cells is the same as in Example 1, except for the carbon material manufacturing process.

[0240] 100-mesh flake graphite was subjected to mechanical grinding, classification, spheroidization, and purification to obtain natural spheroidal graphite with a volume distribution particle size Dv50 of 17 μm and an ash content of 0.01%. The obtained natural spheroidal graphite was then used as a carbon material to produce half-cells and full-cells.

[0241] Comparative Example 2

[0242] The method for manufacturing half-cells and full-cells is the same as in Example 1, except for the carbon material manufacturing process.

[0243] Mechanical grinding, classification, spheroidization, and purification treatment were performed on 100-mesh flake graphite to obtain natural spheroidal graphite with a volume distribution particle size Dv50 of 17 μm and an ash content of 0.01%.

[0244] The obtained natural spheroidal graphite and petroleum pitch (softening point temperature 120°C, volume distribution particle size Dv50 4.3 μm, coking value 33%) were mixed in a VC mixer at a mass ratio of 100:15 for 30 minutes. The mixed material was then graphitized at 3200°C for 10 hours, and after completion, it was cooled to room temperature to obtain a carbon material.

[0245] Comparative Example 3

[0246] The method for manufacturing half-cells and full-cells is the same as in Example 1, except for the carbon material manufacturing process.

[0247] Mechanical grinding, classification, spheroidization, and purification treatment were performed on 100-mesh flake graphite to obtain natural spheroidal graphite with a volume distribution particle size Dv50 of 17 μm and an ash content of 0.01%.

[0248] The obtained natural spheroidal graphite and petroleum pitch (softening point temperature 120°C, volume distribution particle size Dv50 4.3 μm, coking value 33%) were mixed in a VC mixer at a mass ratio of 100:15 for 30 minutes. The mixed material was then carbonized at 1300°C for 2 hours, and after completion, it was cooled to room temperature to obtain a carbon material.

[0249] Comparative Example 4

[0250] The method for manufacturing half-cells and full-cells is the same as in Example 1, except for the carbon material manufacturing process.

[0251] Mechanical grinding, classification, spheroidization, and purification treatment were performed on 100-mesh flake graphite to obtain natural spheroidal graphite with a volume distribution particle size Dv50 of 17 μm and an ash content of 0.01%.

[0252] Asphalt was added to the wash oil and stirred at high speed to fully dissolve the asphalt, obtaining an asphalt solution. 100 g of natural stone spherical ink was put into a reaction kettle and evacuated for 60 min. When the vacuum degree of the reaction kettle reached 0.07 MPa, the asphalt solution suction valve was opened, and all the asphalt solution was sucked into the reaction kettle. After the liquid supply was completed, the suction valve was closed, the evacuation was stopped, and at the same time, the mixture was stirred at high speed for 40 min. After the pressurized (12 MPa) immersion was completed, the pressure was reduced to make the pressure inside and outside the reaction kettle the same, and then nitrogen gas was introduced and heated to 230 °C to remove the wash oil. After all the wash oil in the reaction kettle was discharged, under the condition of a pressure of 1.5 MPa, the reaction kettle was heated to 410 °C at a heating rate of 5 °C / min, and the thermal polymerization reaction was carried out for 10 hours, then cooled to room temperature and discharged. The obtained material was kept under isostatic pressure (10 MPa) for 30 min, then treated at a high temperature of graphitization (2800 °C) for 4 h, cooled to room temperature, and pulverized. The pulverized material and asphalt were uniformly mixed at a ratio of 100:5, and carbonized at 1000 °C for 5 hours under the protection of nitrogen gas, and then cooled to room temperature to obtain a carbon material without voids inside.

[0253] Examples 2 to 23

[0254] The manufacturing methods of the half-cell and the full-cell are the same as those in Example 1 except that the manufacturing process parameters of the carbon material are adjusted. For details, refer to Table 1.

[0255] Performance test

[0256] (1) Test on the adsorption amount of the carbon material to linseed oil

[0257] Refer to GB / T 3780.2-2017, weigh 20 g of the dried test sample, place the weighed sample in the mixing chamber of the oil absorption meter, cover it with a lid when the temperature of the mixing chamber is 23 °C. Align the constant-speed burette oil delivery port above the hole of the mixing chamber lid. Start the oil absorption meter, when the equipment starts to operate and drips linseed oil, as the oil absorption of the sample increases, the mixture changes from a free-flowing state to a semi-plastic aggregate, and the viscosity of the mixture continuously increases. This viscosity is transmitted to the torque sensor system of the oil absorption meter. When the semi-plastic aggregate reaches the preset torque level due to the dropped oil, the oil absorption meter and the constant-speed burette automatically close. Read the value corresponding to 70% of the maximum torque of the fitting curve, and use the formula A = (V / m)×100 to calculate the adsorption amount A of 100 g of carbon material to linseed oil. Here, V represents the volume of linseed oil consumed by the sample at 70% of the maximum torque, with the unit of ml, and m is the mass of the added sample, with the unit of g.

[0258] (2) Test of specific surface area of carbon material

[0259] Refer to GB / T 19587-2017, test by the nitrogen gas adsorption specific surface area analysis measurement method, and calculate the specific surface area B of the carbon material by the BET (Brunauer Emmett Teller) method. As the test equipment, the Tri-Star 3020 type specific surface area and pore size analysis measurement instrument of Micromeritics, USA can be used.

[0260] (3) X-ray diffraction analysis test of carbon material

[0261] In reference to JIS K0131-1996 and JB / T 4220-2011, tests were performed using an X-ray diffractometer to obtain the peak intensity and full width at half maximum (FWHM) of the diffraction peak corresponding to the (110) crystal plane of the carbon material, and the peak intensity and full width at half maximum (FWHM) of the diffraction peak corresponding to the (002) crystal plane. Then, La(110) and Lc(002) of the carbon material were calculated based on Scherrer's formula. La(110) can represent the crystallite size along the a-axis in the (110) crystal plane of the carbon material, and Lc(002) can represent the crystallite size along the c-axis in the (002) crystal plane of the carbon material. The test instrument may be a Bruker D8 Discover X-ray diffractometer.

[0262] (4) Testing of total pore area in the external and internal regions of carbon materials

[0263] After uniformly mixing the sample manufacturing adhesive with the carbon material powder, apply it to copper foil and dry it at 60°C for 30 minutes to prepare it for use. Cut the sample into 6mm x 6mm pieces and attach them to the sample stage of a CP-type argon ion cross-section polisher. Cut the sample using a plasma beam to obtain a cross-section of the carbon material, ensuring that the cross-section of the carbon material particles passes through the center of the carbon material particles. As the test equipment, the IB-09010 CP-type argon ion cross-section polisher from JEOL Ltd. can be used.

[0264] A scanning electron microscope was used to scan the cross-section of a carbon material. The test can be described in JY / T010-1996. The test instrument may be a Sigma 300 scanning electron microscope from ZEISS GmbH, Germany.

[0265] The region extending 0.25 L from the surface of the carbon material particle into the particle interior is defined as the outer region, and the region inside the outer region is defined as the inner region, where L represents the short axis length of the carbon material particle. The total pore area S1 of the outer region and the total pore area S2 of the inner region of the carbon material particle were calculated using image processing software. The image processing software may also be AVIZO.

[0266] (5) Testing the initial Coulomb efficiency of carbon materials

[0267] At 25°C, the button cell manufactured above was first discharged with a constant current of 0.15mA to 0.005V, left to stand for 5 minutes, and then discharged again with a constant current of 10μA to 0.005V, recording the initial discharge capacity of the button cell. Subsequently, it was charged with a constant current of 0.3mA to 2.0V, and the initial charge capacity of the button cell was recorded. Initial Coulomb efficiency of carbon material (%) = Initial charge capacity of button cell / Initial discharge capacity of button cell × 100%.

[0268] (6) Testing the cycle performance of secondary batteries

[0269] At 25°C, the secondary battery manufactured as described above was charged with a constant current of 1C to the upper cutoff voltage (corresponding to 100% SOC), then charged with a constant voltage until the current reached 0.05C, left to stand for 5 minutes, and then discharged with a constant current of 1C to the lower cutoff voltage (corresponding to 0% SOC). The discharge capacity at this time was recorded as the first discharge capacity. The secondary battery was subjected to a cycle charge / discharge test according to the above method, and the discharge capacity after one cycle was recorded. The capacity retention rate (%) of the secondary battery after 2000 cycles at 25°C = discharge capacity after 2000 cycles / first discharge capacity × 100%.

[0270] (7) Testing the storage performance of secondary batteries

[0271] At 25°C, the secondary battery manufactured as described above is charged with a constant current of 1C until it reaches the upper cutoff voltage (corresponding to 100% SOC), then charged with a constant voltage until the current drops to 0.05C, left to stand for 5 minutes, and then discharged with a constant current of 1C until it reaches the lower cutoff voltage (corresponding to 0% SOC). The discharge capacity at this time is recorded as the discharge capacity before storage.

[0272] At 25°C, the secondary batteries manufactured as described above were charged with a constant current of 1C to the upper cutoff voltage (corresponding to 100% SOC), and then charged with a constant voltage until the current reached 0.05C. Afterward, the secondary batteries were placed in a 60°C constant temperature bath and stored until the discharge capacity after storage decreased to 90% of the discharge capacity before storage. The test was then stopped, and the number of days the secondary batteries were stored was recorded.

[0273] The volume distribution, particle size, tap density, and other parameters of the carbon materials produced in Examples 1 to 23 are all within the ranges described in this application.

[0274] In summary, the test results in Table 2 show that when the carbon material satisfies 36 ≤ A × B ≤ 75, the battery can achieve both high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance. Furthermore, when the carbon material satisfies 38 ≤ A × B ≤ 65, and preferably 39 ≤ A × B ≤ 55, the overall performance of the battery is further improved.

[0275] None of the carbon materials produced in Comparative Examples 1-4 satisfy the 36 ≤ A × B ≤ 75 condition, and none of them can achieve both high initial Coulomb efficiency, high energy density, and good cycle performance and storage performance in a battery.

[0276] In Comparative Example 1, untreated natural spheroidal graphite was used as the carbon material, and it had many voids inside. As can be seen from the measurement results in Table 2, the gram capacity, initial Coulomb efficiency, cycle performance, and storage performance of the battery manufactured using this material were all poor. Furthermore, if the number of battery cycles had not reached 2000, the discharge capacity had decreased to 80% of the initial discharge capacity.

[0277] The carbon materials produced in Comparative Examples 2 and 3 formed a carbon layer coating on the surface of natural spheroidal graphite. However, this carbon layer was only present on the surface of the natural spheroidal graphite, failing to achieve a filling effect. Furthermore, the carbon layer did not effectively prevent the electrolyte from penetrating the pore structure inside the particles. Moreover, the improvement in the initial Coulomb efficiency, cycle performance, and storage performance of the battery was limited.

[0278] In Comparative Example 4, when manufacturing the carbon material, by filling the filler into all the pore structures inside the natural spherical graphite particles in an isostatic pressing method, the volume change of the carbon material particles during the desorption and insertion process of active ions becomes large. At this time, the particles are more likely to be crushed, and furthermore, the improvement effect on the cycle performance and storage performance of the battery is limited. In addition, due to the presence of a large amount of soft carbon inside and / or on the surface of the carbon material particles, the side reactions on the particle surface increase, further affecting the cycle performance and storage performance of the battery. At the same time, the manufacturing process is complex and not suitable for large-scale production.

[0279] 综合表2的测试结果可知,当碳材料颗粒进一步满足S2>S1,优选满足1.3≤S2 / S1≤450,更优选满足1.8≤S2 / S1≤400时,电池的综合性能会进一步提高。此时,碳材料颗粒还具有内部区域孔的数量多和 / 或孔的尺寸大,但外部区域孔的数量少和 / 或孔的尺寸小的特征。碳材料内部区域的孔结构能够确保碳材料颗粒体积变化所需的膨胀空间,从而降低因碳材料颗粒破碎而产生新界面的风险,减少副反应的发生,降低二次电池不可逆容量的损失。由于碳材料外部区域孔的数量少和 / 或孔的尺寸小,使得碳材料颗粒具有更稳定的结构,并且能够尽可能避免电解液侵入碳材料颗粒内部的孔结构,从而减少副反应的发生,降低颗粒内部SEI膜形成时活性离子的消耗。由此,进一步满足上述结构特征的碳材料能够进一步提高电池的综合性能。

[0280] This application is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea and produces similar effects within the technical scope of this application is included. In addition, various modifications to the embodiments that can be conceived by a person skilled in the art, as long as they do not depart from the spirit of this application, and other forms constructed by combining some of the components of the embodiments are also included within the scope of this application. [Table 1] [Table 2]

Claims

1. A carbon material containing a pore structure, If A is the amount of carbon material adsorbed by 100g of the carbon material into linseed oil, and B is the specific surface area of ​​the carbon material, then the carbon material satisfies 36 ≤ A × B ≤ 75, the unit of the amount A of adsorbed by 100g of the carbon material into linseed oil is ml, and the unit of the specific surface area B of the carbon material is m ２ / g, The carbon material comprises an outer region and an inner region located inside the outer region, wherein the outer region is a region extending 0.25 L from the particle surface of the carbon material into the particle interior, L being the minor axis length of the carbon material particle, the total pore area of ​​the outer region being S1, the total pore area of ​​the inner region being S2, and S2 > S1.

2. The carbon material according to claim 1, wherein 38 ≤ A × B ≤ 65.

3. The amount A adsorbed by 100g of the carbon material onto linseed oil is 30ml to 50ml, and / or The specific surface area B of the carbon material is 0.5 m². ２ / g to 2.1m ２ The carbon material according to claim 1, wherein the value is / g.

4. The carbon material has a pore area of ​​0.1 μm². ２ The carbon material according to claim 1, comprising one or more of the above-mentioned pore structures.

5. The carbon material according to claim 1, wherein 1.3 ≤ S² / S¹ ≤ 450.

6. 1.8≦S ２ / S １ The carbon material according to claim 5, wherein the coefficient of carbon is ≤ 400.

7. 0.01 μm ２ ≤ S １ ≤ 12.0 μm ２ and / or 2.5 μm ２ ≤S ２ ≤25.0 μm ２ and / or, The carbon material according to claim 5, wherein L ≥ 4 μm.

8. The area of ​​the pore structure in the external region of the carbon material is 0.2 μm². ２ The following and / or, The internal region of the carbon material has an area of ​​0.15 μm ２ The carbon material according to claim 5, comprising one or more pore structures as described above.

9. The interlayer distance in the outer region of the carbon material is d １ Let d be the interlayer distance in the internal region of the carbon material. ２ Therefore, the carbon material is d １ ≥ d ２ A carbon material according to claim 5, satisfying the requirements.

10. d １ The wavelengths are 0.33565 nm to 0.33610 nm, and / or d ２ The carbon material according to claim 9, wherein the wavelength is 0.33557 nm to 0.33585 nm.

11. The degree of graphitization of the carbon material is 94% to 98%, and / or The La(110) of the carbon material is 100 nm to 150 nm, and / or The carbon material according to claim 1, wherein the Lc(002) of the carbon material is 20 nm to 45 nm.

12. The carbon material according to claim 1, which satisfies at least one of the following conditions. (1) The volume distribution particle size Dv50 of the carbon material is 8.0 μm to 24.0 μm. (2) The volume distribution particle size Dv10 of the carbon material is 5.0 μm to 15.0 μm. (3) The volume distribution particle size Dv90 of the carbon material is 16.0 μm to 35.0 μm. (4) The (Dv90 - Dv10) / Dv50 of the carbon material is 0.55 to 1.

55. (5) The tap density of the carbon material is 0.80 g / cm³. ３ ~1.32 g / cm ３ That is the case. (6) The gram capacity of the carbon material is 355 mAh / g to 371 mAh / g. (7) The form of the carbon material includes one or more of the following: massive, spherical, and substantially spherical.

13. Step 1 involves preparing a raw material having multiple pore structures, The raw materials and filler are uniformly mixed in a predetermined ratio, and then the mixture is heated to a first temperature T １ First hour １ Step 2 involves maintaining the temperature to obtain an intermediate, The obtained intermediate is heated to the second temperature T ２ In the second hour ２ A method for producing a carbon material, comprising step 3 of maintaining temperature to obtain a carbon material, The mass ratio of the filler to the raw material is (10-32):

100. The first temperature T1 is 700°C to 1100°C. The first time interval t1 is between 0.5h and 5h. The aforementioned second temperature T2 is between 1920°C and 2520°C. The aforementioned second time t2 is between 1h and 6h. The carbon material includes a porous structure, and if the amount of carbon material adsorbed onto linseed oil by 100g is A, and the specific surface area of ​​the carbon material is B, then the carbon material satisfies 36 ≤ A × B ≤ 75, the unit of the amount of carbon material adsorbed onto linseed oil A by 100g is ml, and the unit of the specific surface area B of the carbon material is m ２ / g, A method for manufacturing a carbon material, wherein the carbon material includes an outer region and an inner region located inside the outer region, the outer region is a region extending 0.25 L from the particle surface of the carbon material into the particle interior, L is the minor axis length of the carbon material particle, the total pore area of ​​the outer region is S1, the total pore area of ​​the inner region is S2, and S2 > S1.

14. The method according to claim 13, wherein the raw material satisfies at least one of the following conditions. (1) The raw materials include natural graphite. (2) The volume distribution particle size Dv50 of the raw material is 8.5 μm to 24.0 μm. (3) The ash content in the raw material is 1 wt% or less.

15. The method according to claim 13, wherein the filler satisfies at least one of the following conditions. (1) The softening point temperature of the filler is 110°C to 175°C. (2) The caulking value of the filler is 26% to 50%. (3) The volume distribution particle size Dv50 of the filler is 6 μm or less. (4) The content of quinoline insoluble matter in the filler is 1 wt% or less.

16. The method according to claim 15, wherein the filler includes one or more types selected from coal pitch and petroleum pitch.

17. The method according to claim 13, wherein the mass ratio of the filler to the raw material is (10-25):

100.

18. After uniformly mixing the raw materials and the filler in a predetermined ratio, the first temperature T １ The method according to claim 13, wherein the heating process to raise the temperature is a stepwise heating process.

19. The heating process includes a first heating process, a second heating process and a third heating process, The first heating process involves raising the temperature to 200°C to 250°C and maintaining that temperature for 0.5 hours to 2 hours, and / or The second heating process involves raising the temperature to 450°C to 550°C and maintaining that temperature for 0.5 hours to 2 hours, and / or The third heating process is the first temperature T １ The temperature is raised to that point, and the temperature is maintained for the first hour t. １ The method according to claim 18, wherein the method involves keeping the body warm.

20. The first temperature T is heated at a rate of 1°C / min to 10°C / min. １ The method according to claim 13, wherein the temperature is raised to a certain level.

21. the first temperature T １ The temperature range is 750°C to 1100°C, and / or The first time t １ The method according to claim 13, wherein the interval is 0.5h to 3h.

22. Said second temperature T ２ The temperature range is 2050°C to 2400°C, and / or The second time t ２ The method according to claim 13, wherein the time is 2 to 5 hours.

23. A secondary battery comprising a negative electrode sheet containing the carbon material described in any one of claims 1 to 12.

24. A power consumption device comprising a secondary battery as described in claim 23.

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