Carbon negative electrode material precursor, application thereof, carbon negative electrode material, preparation method and application thereof, and lithium ion battery

Abstract

The present application relates to the technical field of lithium ion batteries, in particular to a carbon negative electrode material precursor and application thereof, a carbon negative electrode material and preparation method and application thereof, and a lithium ion battery. The carbon negative electrode material precursor comprises first needle-shaped coke (a1, k1), second needle-shaped coke (a2, k2) and third needle-shaped coke (a3, k3), wherein a1, a2 and a3 respectively represent the total content of large pieces and fiber structure in the anisotropic structure of coke particles; k1, k2 and k3 respectively represent the aspect ratio of coke particles; wherein a1≠a2≠a3, and k1≠k2≠k3; wherein the weight ratio of the first needle-shaped coke (a1, k1), the second needle-shaped coke (a2, k2) and the third needle-shaped coke (a3, k3) is 10-20:60-70:15-25. The carbon negative electrode material precursor is used for lithium ion batteries, and improves the first discharge specific capacity and the first coulomb efficiency of the lithium ion batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, specifically to a carbon anode material precursor and its application, a carbon anode material and its preparation method and application, and a lithium-ion battery. Background Technology

[0002] Lithium-ion batteries possess characteristics such as high capacity, high energy density, high cycle stability, and environmental friendliness, making them a new generation of green energy. With the rapid development of electric vehicles and portable devices, not only has the demand for lithium-ion batteries increased, but higher performance requirements have also been placed on them. Improving the electrochemical performance of materials and their structural design have become effective ways to enhance the energy storage capacity of lithium-ion batteries. As a crucial component of lithium batteries, most anode materials require modification to improve their electrochemical activity.

[0003] Needle coke, as a petroleum-processed product, is a high-quality raw material for artificial graphite due to its unique needle-like structure, high conductivity, ease of graphitization, and favorable graphite crystal structure. However, due to lithium-ion intercalation storage kinetics and volume expansion effects, there is still room for improvement in specific capacity and rate performance. To improve the electrochemical performance of graphite, efforts are being made to improve the raw materials and production processes for high-quality needle coke (e.g., CN202010646862.7); on the other hand, there has been considerable research on structural design and modification, such as surface carbon coating and particle size adjustment (e.g., CN201710616466.8, CN202010207606.8, CN201711351496.7, CN202011552394.3). However, the production of high-quality needle coke often requires stringent requirements in terms of raw materials and preparation processes, posing a challenge for large-scale industrial scale-up. Furthermore, the methods of carbon coating and particle size sieving do not significantly improve the structure and properties of the raw material needle coke itself, thus limiting the improvement of the performance of lithium battery anode materials. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of long lithium-ion transport paths and high transport resistance in existing carbon anode materials based on needle coke, as well as the low specific capacity and low initial discharge efficiency of lithium-ion batteries made from carbon anode materials. This invention provides a carbon anode material precursor and its application, a carbon anode material and its preparation method and application, and a lithium-ion battery. The carbon anode material precursor combines the microscopic and macroscopic properties of needle coke and coordinates different types of needle coke, so that the lithium-ion battery containing the carbon anode material precursor has high capacity and high rate performance.

[0005] To achieve the above objectives, the first aspect of the present invention provides a carbon anode material precursor, the carbon anode material precursor comprising: a first needle-shaped coke (a1, k1), a second needle-shaped coke (a2, k2), and a third needle-shaped coke (a3, k3), wherein a1, a2, and a3 represent the total content of large sheet and fibrous structures in the anisotropic structure of the coke particles, respectively; and k1, k2, and k3 represent the aspect ratio of the coke particles, respectively.

[0006] Where a1≠a2≠a3, and k1≠k2≠k3;

[0007] The weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 10-20:60-70:15-25.

[0008] Preferably, a1 < a2 < a3, and k1 < k2 < k3.

[0009] Preferably, the first needle coke satisfies: 70% ≤ a1 < 80%, and 1.68 ≤ k1 < 1.78; the second needle coke satisfies: 80% ≤ a2 < 90%, and 1.78 ≤ k2 < 1.85; and the third needle coke satisfies: 90% ≤ a3 < 100%, and 1.85 ≤ k3 < 1.95.

[0010] The second aspect of this invention provides an application of the carbon anode material precursor provided in the first aspect in carbon anode materials.

[0011] A third aspect of the present invention provides a carbon anode material, the carbon anode material comprising: the carbon anode material precursor provided in the first aspect, and asphalt coating.

[0012] Preferably, based on the total weight of the carbon anode material, the content of the carbon anode material precursor is 80-95 wt%, more preferably 85-90 wt%; and the content of the coated asphalt is 5-20 wt%, more preferably 10-15 wt%.

[0013] Preferably, the coated asphalt is obtained by graphitizing high-temperature asphalt.

[0014] A fourth aspect of the present invention provides a method for preparing a carbon anode material, the method comprising the following steps:

[0015] (1) The first needle coke (a1, k1), the second needle coke (a2, k2) and the third needle coke (a3, k3) are mixed to obtain a carbon anode material precursor; wherein a1, a2 and a3 represent the total content of large sheet and fiber structure in the anisotropic structure of the coke particles, respectively; k1, k2 and k3 represent the aspect ratio of the coke particles, respectively; wherein a1≠a2≠a3 and k1≠k2≠k3;

[0016] (2) The carbon anode material precursor and high-temperature asphalt are coated to obtain a coated product;

[0017] (3) The coated product is graphitized in a non-oxidizing atmosphere to obtain a carbon anode material;

[0018] The weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 10-20:60-70:15-25.

[0019] The fifth aspect of this invention provides an application of the carbon anode material provided in the third aspect, or the carbon anode material prepared by the preparation method provided in the fourth aspect, in a lithium-ion battery.

[0020] The sixth aspect of the present invention provides a lithium-ion battery, wherein the lithium-ion battery contains a carbon anode material provided in the third aspect, or a carbon anode material prepared by the preparation method provided in the fourth aspect.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The carbon anode material precursor provided by the present invention is achieved by controlling different needle cokes with different microscopic and macroscopic characteristics. The microscopic characteristics refer to the total content of large sheet and fiber structures in the anisotropic structure of the coke particles, and the macroscopic characteristics refer to the aspect ratio of the coke particles. This makes the carbon anode material precursor have a high degree of graphitization and can shorten the lithium ion transport path and reduce the transport resistance. In particular, by controlling the parameters and weight ratio of different needle cokes, the carbon anode material precursor has high performance.

[0023] (2) The carbon anode material precursor provided by the present invention is used to prepare carbon anode material, which realizes the classified use of different needle coke, expands the selection range of raw materials, improves the utilization rate of materials, reduces production costs, and has high application potential in the field of lithium-ion batteries.

[0024] (3) The preparation method of carbon anode material provided by the present invention simplifies the process flow and facilitates industrial production; in particular, by controlling the conditions of coating treatment and graphitization treatment, the performance of carbon anode material is further improved.

[0025] (4) The carbon anode material provided by the present invention is used in lithium-ion batteries, which improves the electrochemical performance of lithium-ion batteries, especially the first discharge specific capacity and the first coulombic efficiency. Attached Figure Description

[0026] Figure 1These are polarized light microstructure diagrams of three types of needle focal lengths; Figure (1-1) is the polarized light microstructure diagram of the first needle focal length; Figure (1-2) is the polarized light microstructure diagram of the second needle focal length; and Figure (1-3) is the polarized light microstructure diagram of the third needle focal length. Detailed Implementation

[0027] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0028] In this invention, unless otherwise specified, "first," "second," and "third" do not indicate a sequence or limit the various materials or steps; they are merely used to distinguish or indicate that these are not the same material or step. For example, in "first needle coke," "second needle coke," and "third needle coke," "first," "second," and "third" are used only to indicate that these are not the same needle coke.

[0029] The first aspect of the present invention provides a carbon anode material precursor, the carbon anode material precursor comprising: a first needle-shaped coke (a1, k1), a second needle-shaped coke (a2, k2) and a third needle-shaped coke (a3, k3), wherein a1, a2 and a3 represent the total content of large sheet and fibrous structures in the anisotropic structure of the coke particles, respectively; k1, k2 and k3 represent the aspect ratio of the coke particles, respectively;

[0030] Where a1≠a2≠a3, and k1≠k2≠k3;

[0031] The weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 10-20:60-70:15-25.

[0032] The inventors of this invention have discovered that anode materials can be prepared using needle coke with different microscopic and macroscopic characteristics. Microscopic characteristics are characterized by the total content of large flakes and fibers in the anisotropic structure of the coke particles, while macroscopic characteristics are represented by the aspect ratio of the coke particles. Specifically, needle coke with a high total content of large flakes and fibers in its anisotropic structure and a large aspect ratio has a complete crystal structure and a high degree of graphitization, making it suitable as a major component of anode materials. However, it has a longer lithium-ion transport path and greater transport resistance. Conversely, needle coke with a low total content of large flakes and fibers in its anisotropic structure and a smaller aspect ratio reduces anisotropy to a certain extent, shortening the lithium-ion transport path and reducing transport resistance. Therefore, the inventors employed a first needle coke (a1, k1), a second needle coke (a2, k2), and a third needle coke (a3, k3) in synergy, and combined the weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) to make the carbon anode material precursor have a high degree of graphitization and low transport resistance. As a result, the product containing the carbon anode material precursor has a higher specific capacity and first discharge efficiency, that is, the electrochemical performance of the product is improved.

[0033] In this invention, unless otherwise specified, the first needle-shaped coke (a1, k1) refers to the first needle-shaped coke that satisfies the following conditions: the total content of large flakes and fibrous structures in the anisotropic structure of the coke particles is a1, and the aspect ratio of the coke particles is k1; similarly, the second needle-shaped coke (a2, k2) refers to the second needle-shaped coke that satisfies the following conditions: the total content of large flakes and fibrous structures in the anisotropic structure of the coke particles is a2, and the aspect ratio of the coke particles is k2; the third needle-shaped coke (a3, k3) refers to the third needle-shaped coke that satisfies the following conditions: the total content of large flakes and fibrous structures in the anisotropic structure of the coke particles is a3, and the aspect ratio of the coke particles is k3.

[0034] In this invention, unless otherwise specified, a1, a2, and a3 represent the total content of large flakes and fibrous structures in the anisotropic structure of the coke particles, respectively. Specifically, a1 represents the total content of large flakes and fibrous structures in the anisotropic structure of the first needle-shaped coke particle, a2 represents the total content of large flakes and fibrous structures in the anisotropic structure of the second needle-shaped coke particle, and a3 represents the total content of large flakes and fibrous structures in the anisotropic structure of the third needle-shaped coke particle; k1, k2, and k3 represent the aspect ratio of the coke particles, respectively. Specifically, k1 represents the aspect ratio of the first needle-shaped coke particle, k2 represents the aspect ratio of the second needle-shaped coke particle, and k3 represents the aspect ratio of the third needle-shaped coke particle.

[0035] In this invention, unless otherwise specified, the total content of large flakes and fibrous structures in the anisotropic structure of coke particles refers to the total content of large flakes, short fibers, fine fibers, and coarse fibers in the anisotropic structure of coke particles.

[0036] In this invention, unless otherwise specified, the total content parameters of large-scale and fibrous structures in the anisotropic structure of coke particles and the aspect ratio parameters of coke particles are characterized by taking pictures under a polarizing microscope. The anisotropic structure of coke particles is quantitatively analyzed using ImageJ analysis software, and the aspect ratio of coke particles is measured. When analyzing the optical structure, points are taken with a dot spacing of 300 μm and a row spacing of 500 μm, and the type of anisotropic structure at each point is analyzed by dot counting method.

[0037] In some embodiments of the present invention, preferably, a1 < a2 < a3, and k1 < k2 < k3. That is, the total content of large flakes and fibrous structures in the anisotropic structure of the first needle-shaped coke particle is less than the total content of large flakes and fibrous structures in the anisotropic structure of the second needle-shaped coke particle, and the aspect ratio of the first needle-shaped coke particle is less than the aspect ratio of the second needle-shaped coke particle; at the same time, the total content of large flakes and fibrous structures in the anisotropic structure of the second needle-shaped coke particle is less than the total content of large flakes and fibrous structures in the anisotropic structure of the third needle-shaped coke particle, and the aspect ratio of the second needle-shaped coke particle is less than the aspect ratio of the third needle-shaped coke particle.

[0038] In some specific embodiments of the present invention, preferably, such as Figure 1 As shown, the first needle coke satisfies: 70% ≤ a1 < 80%, and 1.68 ≤ k1 < 1.78; the second needle coke satisfies: 80% ≤ a2 < 90%, and 1.78 ≤ k2 < 1.85; the third needle coke satisfies: 90% ≤ a3 < 100%, and 1.85 ≤ k3 < 1.95. Here, a1, a2, and a3 are all expressed as percentages.

[0039] In some embodiments of the present invention, preferably, the weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 10-20:60-70:15-25, for example, 10:65:25, 10:70:20, 12:64:24, 15:65:20, 18:66:16, 20:60:20, 20:63:17, and any value within any range of any two values, preferably 12-18:62-68:16-24. Using the preferred weight ratio is more beneficial for improving the graphitization degree of the carbon anode material precursor and shortening the lithium-ion transport path. In the present invention, unless otherwise specified, the sum of the weight ratios of the first needle coke, the second needle coke, and the third needle coke is 100.

[0040] The second aspect of this invention provides an application of the carbon anode material precursor provided in the first aspect in carbon anode materials.

[0041] Using the carbon anode material precursor provided by this invention in carbon anode materials not only broadens the sources of carbon anode materials but also improves the classification and use of different needle cokes, thereby increasing the utilization rate of materials and reducing production costs.

[0042] A third aspect of the present invention provides a carbon anode material, the carbon anode material comprising the carbon anode material precursor provided in the first aspect, and asphalt-coated asphalt.

[0043] In some embodiments of the present invention, preferably, based on the total weight of the carbon anode material, the content of the carbon anode material precursor is 80-95 wt%, for example, 80 wt%, 85 wt%, 90 wt%, 95 wt%, or any value within the range of any two values, preferably 85-90 wt%; the content of the coated bitumen is 5-20 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 20 wt%, or any value within the range of any two values, preferably 10-15 wt%.

[0044] In some embodiments of the present invention, preferably, the coated asphalt is obtained by graphitizing high-temperature asphalt.

[0045] In this invention, a wide range of types of high-temperature asphalt can be selected. Preferably, the softening point of the high-temperature asphalt is 105-120℃, and the quinoline insoluble content of the high-temperature asphalt is ≤0.2wt%. In this invention, the softening point parameter is obtained by testing using the Mettler Toledo dropping point system; the quinoline insoluble content parameter is measured according to the method of GB / T 2293-2019.

[0046] In one specific embodiment of the present invention, the high-temperature asphalt is selected from high-temperature petroleum asphalt with a softening point of 105-120℃ and a quinoline insoluble content of ≤0.2wt%.

[0047] In some embodiments of the present invention, preferably, the specific surface area of ​​the carbon anode material is ≤2m². 2 / g, preferably ≤1.7m 2 / g; tap density ≥1g / cm³ 3 Preferably, it is ≥1.1g / cm 3 In this invention, lithium-ion batteries assembled from carbon anode materials that satisfy the above-mentioned preferred protection range exhibit excellent electrochemical performance, especially in terms of initial discharge specific capacity and initial coulombic efficiency.

[0048] In this invention, unless otherwise specified, the specific surface area parameter is measured using a BET specific surface area tester; the tap density parameter is measured using a YSPK-12 tap density tester.

[0049] A fourth aspect of the present invention provides a method for preparing a carbon anode material, the method comprising the following steps:

[0050] (1) The first needle coke (a1, k1), the second needle coke (a2, k2) and the third needle coke (a3, k3) are mixed to obtain a carbon anode material precursor; wherein a1, a2 and a3 represent the total content of large sheet and fiber structure in the anisotropic structure of the coke particles, respectively; k1, k2 and k3 represent the aspect ratio of the coke particles, respectively; wherein a1≠a2≠a3 and k1≠k2≠k3;

[0051] (2) The carbon anode material precursor and high-temperature asphalt are coated to obtain a coated product;

[0052] (3) The coated product is graphitized in a non-oxidizing atmosphere to obtain a carbon anode material;

[0053] The weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 10-20:60-70:15-25.

[0054] In this invention, unless otherwise specified, the types of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3), as well as the types of high-temperature asphalt, are all defined as described above, and will not be elaborated upon here.

[0055] In this invention, the mixing conditions have a wide range of selection, as long as the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) are mixed evenly. Preferably, in step (1), the mixing process includes: (1-1) mixing the first needle coke (a1, k1) and the second needle coke (a2, k2) to obtain a first mixture; (1-2) mixing the first mixture with the third needle coke (a3, k3).

[0056] In some embodiments of the present invention, preferably, in steps (1-2), a portion of the first mixture and the third needle coke (a3, k3) are first mixed, and then the remaining portion of the first mixture is added and mixed. The weight ratio of the portion of the first mixture to the first mixture is 1-2:3, for example, 1:3, 1.5:3, 2:3, or any value within the range of any two values. This arrangement is more conducive to obtaining a uniformly mixed carbon anode material precursor.

[0057] In some embodiments of the present invention, preferably, before the mixing, the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) are each independently and sequentially crushed and sieved, and the D50 of the crushed and sieved first needle coke (a1, k1), second needle coke (a2, k2), and third needle coke (a3, k3) is each 10-20 μm.

[0058] In one specific embodiment of the present invention, the first needle coke (a1, k1) after being crushed and sieved and the second needle coke (a2, k2) after being crushed and sieved are mixed for 1 hour to obtain a first mixture; 1 / 3 to 2 / 3 of the first mixture and the third needle coke (a3, k3) after being crushed and sieved are mixed for 0.5 hours, and then the remaining part of the first mixture is added and mixed for 0.5 hours to obtain a carbon anode material precursor.

[0059] In some embodiments of the present invention, preferably, in step (2), the weight ratio of the carbon anode material precursor to the high-temperature asphalt is 80-95:5-20, for example, 80:20, 83:17, 85:15, 90:10, 95:5, and any value within any range of two such values, preferably 85-90:10-25. In the present invention, the polycyclic aromatic hydrocarbon structure formed by the cross-linking and curing of the high-temperature asphalt after coating and graphitization is similar to that of graphite material and has a strong binding force, which can improve the compatibility between the anode material and the electrolyte, prevent solvent co-intercalation and decomposition, and avoid graphite structure peeling. Therefore, the content of the coated asphalt has a significant impact on the product performance and is related to the surface area of ​​the particles.

[0060] In this invention, when the weight ratio of the carbon anode material precursor to high-temperature asphalt is less than 80:20, the resulting anode material semi-finished product will be in clumps or blocks; when the weight ratio is greater than 95:5, it cannot fully exert its function of coating and filling internal pores and cracks; some exposed parts of the anode material surface will still exist, which will react with the solvent in the electrolyte, affecting the charge and discharge efficiency. Therefore, whether the weight ratio of the carbon anode material precursor to high-temperature asphalt is less than 80:20 or greater than 95:5, it will affect the performance of the final product.

[0061] In some embodiments of the present invention, preferably, the coating process includes: a first coating stage, a second coating stage, and a third coating stage; more preferably, the conditions of the first coating stage include: heating to 180-260°C, preferably 200-240°C, at a heating rate of 2-8°C / min; a time of 1-4 hours, preferably 2-3 hours; and a rotation speed of 200-500 rpm, preferably 300-400 rpm; the conditions of the second coating stage include: cooling to 10-15°C above the softening point of the high-temperature asphalt at a cooling rate of 2-8°C / min; and a rotation speed of 100-300 rpm, preferably 150-250 rpm; the third coating stage includes: cooling to 25°C at a cooling rate of 5-10°C / min.

[0062] In this invention, a wide range of non-oxidizing atmospheres can be selected. Preferably, the non-oxidizing atmosphere includes, but is not limited to, nitrogen, argon, and helium, but is preferably nitrogen or argon.

[0063] In some embodiments of the present invention, preferably, in step (3), the conditions for the graphitization treatment include: a first graphitization stage and a second graphitization stage; more preferably, the conditions for the first graphitization stage include: heating to 1000-1500℃ at a heating rate of 1-10℃ / min, preferably 1100-1300℃; and a time of 8-18h, preferably 10-15h; the conditions for the second graphitization stage include: heating to 2500-3500℃ at a heating rate of 1-10℃ / min, preferably 2800-3000℃; and a time of 15-30h, preferably 15-24h.

[0064] In some embodiments of the present invention, preferably, the method further includes: sieving the graphitized product to obtain the carbon anode material. In the present invention, the sieving includes, but is not limited to, airflow ultrasonic sieving.

[0065] The fifth aspect of this invention provides an application of the carbon anode material provided in the third aspect, or the carbon anode material prepared by the preparation method provided in the fourth aspect, in a lithium-ion battery.

[0066] The sixth aspect of the present invention provides a lithium-ion battery, the lithium-ion battery comprising: the carbon anode material provided in the third aspect, or the carbon anode material prepared by the preparation method provided in the fourth aspect.

[0067] According to a particularly preferred embodiment of the present invention, a carbon anode material is provided, the carbon anode material comprising a carbon anode material precursor and a coated bitumen; based on the total weight of the carbon anode material, the content of the carbon anode material precursor is 80-95 wt%, preferably 85-90 wt%; the content of the coated bitumen is 5-20 wt%, preferably 10-15 wt%.

[0068] The carbon anode material precursor includes: a first needle-shaped coke (a1, k1), a second needle-shaped coke (a2, k2), and a third needle-shaped coke (a3, k3), wherein a1, a2, and a3 represent the total content of large sheet and fibrous structures in the anisotropic structure of the coke particles, respectively; and k1, k2, and k3 represent the aspect ratio of the coke particles, respectively.

[0069] Wherein, the first needle coke satisfies: 70% ≤ a1 < 80%, and 1.68 ≤ k1 < 1.78; the second needle coke satisfies: 80% ≤ a2 < 90%, and 1.78 ≤ k2 < 1.85; the third needle coke satisfies: 90% ≤ a3 < 100%, and 1.85 ≤ k3 < 1.95;

[0070] The weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 12-18:62-68:16-24.

[0071] The present invention will be described in detail below through embodiments.

[0072] The total content parameters of large-scale and fibrous structures in the anisotropic structure of coke particles and the aspect ratio parameters of coke particles were characterized by taking pictures under a polarizing microscope. The anisotropic structure of coke particles was quantitatively analyzed using ImageJ analysis software, and the aspect ratio of coke particles was measured. When analyzing the optical structure, points were taken with a dot spacing of 300 μm and a row spacing of 500 μm, and the type of anisotropic structure at each point was analyzed by dot counting method.

[0073] The softening point parameter was obtained using the Mettler Toledo dropping point system; the quinoline insoluble content parameter was determined according to GB / T2293-2019; the specific surface area parameter was measured using a BET specific surface area tester; and the tap density parameter was measured using a YSPK-12 tap density tester.

[0074] The physical properties of the carbon anode materials prepared in Examples 1-12 and Comparative Examples 1-2 are listed in Table 1.

[0075] Example 1

[0076] (1) In a high-speed mixer, at a speed of 1000 rpm, the first needle coke (79%, 1.77) with a D50 of 15.3 μm after crushing and screening and the second needle coke (88%, 1.84) with a D50 of 12.8 μm after crushing and screening are mixed for 1 h to obtain the first mixture; half of the first mixture is mixed with the third needle coke (91%, 1.85) with a D50 of 17.2 μm after crushing and screening for 0.5 h, and then the remaining part of the first mixture is added and mixed for 0.5 h to obtain the carbon anode material precursor; wherein the weight ratio of the first needle coke, the second needle coke and the third needle coke is 15:65:20;

[0077] (2) The carbon anode material precursor and high-temperature asphalt (high-temperature petroleum asphalt with a softening point of 106°C and a quinoline insoluble content of 0.08 wt%) are coated to obtain a coated product; wherein the weight ratio of the carbon anode material precursor and the high-temperature asphalt is 88:12.

[0078] The conditions for the first coating stage include: heating to 220°C at a heating rate of 5°C / min for 2 hours at a rotation speed of 300 rpm; the conditions for the second coating stage include: cooling to 120°C at a cooling rate of 2°C / min at a rotation speed of 150 rpm; and the conditions for the third coating stage include: cooling to 25°C at a cooling rate of 10°C / min.

[0079] (3) The above-mentioned coated product is graphitized in an argon atmosphere. The conditions of the first graphitization stage include: heating to 1300℃ at a heating rate of 5℃ / min for 12h; the conditions of the second graphitization stage include: heating to 3000℃ at a heating rate of 5℃ / min for 24h. The graphitized product is then subjected to ultrasonic sieving by airflow to obtain carbon anode material S1.

[0080] The carbon anode material S1 includes: a carbon anode material precursor and a coated pitch; based on the total weight of the carbon anode material S1, the content of the carbon anode material precursor is 88 wt%, and the content of the carbon coating layer is 12 wt%.

[0081] Example 2

[0082] (1) In a high-speed mixer, at a speed of 1200 rpm, the first needle coke (75%, 1.73) with a D50 of 12.4 μm after crushing and screening and the second needle coke (80%, 1.79) with a D50 of 16.2 μm after crushing and screening are mixed for 1 h to obtain the first mixture; half of the first mixture is mixed with the third needle coke (96%, 1.92) with a D50 of 13.9 μm after crushing and screening for 0.5 h, and then the remaining part of the first mixture is added and mixed for 0.5 h to obtain the carbon anode material precursor; wherein, the weight ratio of the first needle coke, the second needle coke and the third needle coke is 12:64:24;

[0083] (2) The carbon anode material precursor and high-temperature asphalt (high-temperature petroleum asphalt with a softening point of 110°C and a quinoline insoluble content of 0.06 wt%) are coated to obtain a coated product; wherein the weight ratio of the carbon anode material precursor and the high-temperature asphalt is 88:12.

[0084] The conditions for the first coating stage include: heating to 200°C at a heating rate of 5°C / min for 3 hours and rotating at 350 rpm; the conditions for the second coating stage include: cooling to 120°C at a cooling rate of 5°C / min and rotating at 200 rpm; the conditions for the third coating stage include: cooling to 25°C at a cooling rate of 8°C / min.

[0085] (3) The above-mentioned coated product is graphitized in an argon atmosphere. The conditions of the first graphitization stage include: heating to 1200℃ at a heating rate of 5℃ / min for 15h; the conditions of the second graphitization stage include: heating to 3000℃ at a heating rate of 5℃ / min for 20h. The graphitized product is then subjected to ultrasonic sieving by airflow to obtain carbon anode material S2.

[0086] The carbon anode material S2 includes: a carbon anode material precursor and coated bitumen; based on the total weight of the carbon anode material S2, the content of the carbon anode material precursor is 88 wt% and the content of the coated bitumen is 12 wt%.

[0087] Example 3

[0088] (1) In a high-speed mixer, at a speed of 1500 rpm, the first needle coke (71%, 1.68) with a D50 of 18.1 μm after crushing and screening and the second needle coke (84%, 1.81) with a D50 of 14.6 μm after crushing and screening are mixed for 1 h to obtain the first mixture; half of the first mixture is mixed with the third needle coke (94%, 1.89) with a D50 of 11.9 μm after crushing and screening for 0.5 h, and then the remaining part of the first mixture is added and mixed for 0.5 h to obtain the carbon anode material precursor; wherein the weight ratio of the first needle coke, the second needle coke and the third needle coke is 18:66:16;

[0089] (2) The carbon anode material precursor and high-temperature asphalt (high-temperature petroleum asphalt with a softening point of 110°C and a quinoline insoluble content of 0.06 wt%) are coated to obtain a coated product; wherein the weight ratio of the carbon anode material precursor and the high-temperature asphalt is 88:12.

[0090] The conditions for the first coating stage include: heating to 220°C at a heating rate of 5°C / min for 3 hours at a rotation speed of 400 rpm; the conditions for the second coating stage include: cooling to 125°C at a cooling rate of 8°C / min at a rotation speed of 250 rpm; and the conditions for the third coating stage include: cooling to 25°C at a cooling rate of 5°C / min.

[0091] (3) The above-mentioned coated product is graphitized in an argon atmosphere. The conditions of the first graphitization stage include: heating to 1300℃ at a heating rate of 4℃ / min for 12h; the conditions of the second graphitization stage include: heating to 3000℃ at a heating rate of 5℃ / min for 24h. The graphitized product is then subjected to ultrasonic sieving by airflow to obtain carbon anode material S3.

[0092] The carbon anode material S3 includes a carbon anode material precursor and a coated asphalt. Based on the total weight of the carbon anode material S3, the content of the carbon anode material precursor is 88 wt% and the content of the coated asphalt is 12 wt%.

[0093] Example 4

[0094] The method is the same as in Example 1, except that in step (1),

[0095] By replacing the weight ratio of the first needle coke, the second needle coke, and the third needle coke with 10:70:20, and keeping all other conditions the same, carbon anode material S4 was obtained.

[0096] Example 5

[0097] The method is the same as in Example 1, except that in step (1),

[0098] The first needle coke, the second needle coke, and the third needle coke were directly mixed, and all other conditions were the same, to obtain carbon anode material S5.

[0099] Example 6

[0100] The method is the same as in Example 1, except that in step (1), the first needle-shaped coke, the second needle-shaped coke, and the third needle-shaped coke are not broken, that is,

[0101] The D50 of the first needle coke was replaced with 30.6 μm, the D50 of the second needle coke was replaced with 28.1 μm, and the D50 of the third needle coke was replaced with 25.7 μm. All other conditions were the same, and carbon anode material S6 was obtained.

[0102] Example 7

[0103] The method is the same as in Example 1, except that in step (2),

[0104] By replacing the weight ratio of the carbon anode material precursor and high-temperature asphalt to 80:20, while keeping all other conditions the same, carbon anode material S7 was obtained.

[0105] Example 8

[0106] The method is the same as in Example 1, except that in step (2),

[0107] The high-temperature pitch was replaced with high-temperature coal tar pitch (softening point of 100℃, quinoline insoluble content of 0.15wt%), and the other conditions were the same, to obtain carbon anode material S8.

[0108] Example 9

[0109] The method is the same as in Example 1, except that in step (2),

[0110] The temperature of the second coating stage was replaced by cooling to 126°C at a cooling rate of 5°C / min, with all other conditions remaining the same, to obtain carbon anode material S9.

[0111] Example 10

[0112] The method is the same as in Example 1, except that in step (2),

[0113] The conditions for the first coating stage were changed as follows: the temperature was increased to 220°C at a heating rate of 5°C / min and the rotation speed was 350 rpm, and the coating was kept at a constant temperature for 2 hours; the conditions for the second coating stage were changed as follows: the temperature was cooled to 120°C at a cooling rate of 4°C / min and the rotation speed was 100 rpm; the conditions for the third coating stage were changed as follows: the temperature was cooled to 25°C at a cooling rate of 5°C / min; the other conditions were the same, and carbon anode material S10 was obtained.

[0114] Example 11

[0115] The method is the same as in Example 1, except that in step (3),

[0116] The conditions for the first graphitization stage were replaced by heating to 1000℃ at a heating rate of 10℃ / min for 18 hours; the conditions for the second graphitization stage were replaced by heating to 3200℃ at a heating rate of 10℃ / min for 20 hours, with the other conditions remaining the same, to obtain the carbon anode material S11.

[0117] Example 12

[0118] The method is the same as in Example 1, except that in step (3),

[0119] Replacement of graphitization treatment conditions: The temperature was increased to 3000℃ at 5℃ / min for 24h, with other conditions remaining the same, to obtain carbon anode material S12.

[0120] Comparative Example 1

[0121] The method is the same as in Example 1, except that in step (1),

[0122] By replacing the weight ratio of the first needle coke, the second needle coke, and the third needle coke with 65:20:15, while keeping all other conditions the same, carbon anode material DS1 was obtained.

[0123] Comparative Example 2

[0124] The method is the same as in Example 1, except that in step (1),

[0125] By replacing the weight ratio of the first needle coke, the second needle coke, and the third needle coke with 12:14:74, while keeping all other conditions the same, carbon anode material DS2 was obtained.

[0126] Table 1

[0127]

[0128]

[0129] As can be seen from the results in Table 1, the specific surface area of ​​the carbon anode material obtained using the carbon anode material precursor provided by this invention is ≤2m². 2 / g, tapped density ≥1g / cm³ 3 ;

[0130] Test case

[0131] The carbon anode materials (S1-S12 and DS1-DS2) prepared in Examples 1-12 and Comparative Examples 1-2 were assembled to obtain lithium-ion batteries Q1-Q12 and DQ1-DQ2, respectively.

[0132] Battery Assembly: The electrochemical performance of the half-cells was evaluated using CR2032 coin cells. Active materials (S1-S12 and DS1-DS2), acetylene black, and polyvinylidene fluoride were mixed in a mass ratio of 8:1:1 to obtain a slurry. The slurry was coated onto copper foil, dried in a vacuum oven at 90°C for 12 hours, and then pressed. 1 mol / L LiPF6 dissolved in a 1:1 volume ratio mixture of ethylene carbonate and dimethyl carbonate was used as the electrolyte. Lithium metal was used as the counter electrode, and the half-cells were assembled in a glove box under an Ar atmosphere (H2O and O2 contents both less than 0.01 ppm).

[0133] Among them, the Xinwei BTS3000 battery tester was used to conduct constant current charge and discharge tests on lithium-ion batteries Q1-Q12 and DQ1-DQ2 between 0.01V and 3.0V, with a charge and discharge rate of 0.1C. The first discharge specific capacity and the first coulombic efficiency were tested, and the test results are listed in Table 2.

[0134] Table 2

[0135] First discharge specific capacity, mAh / g First Coulomb efficiency, % Example 1 364.7 94.6 Example 2 365.3 94.1 Example 3 363.7 95.6 Example 4 361.1 93.0 Example 5 359.6 92.7 Example 6 358.2 92.3 Example 7 358.4 92.5 Example 8 359.8 92.1 Example 9 360.2 93.2 Example 10 358.0 92.6 Example 11 360.5 93.5 Example 12 357.9 92.9 Comparative Example 1 348.2 93.9 Comparative Example 2 357.5 91.6

[0136] As can be seen from the results in Table 2, compared with Comparative Examples 1-2, the lithium-ion batteries assembled with carbon anode materials prepared in Examples 1-12 have higher initial discharge specific capacity and initial coulombic efficiency.

[0137] Meanwhile, compared to Examples 4-12, the specific surface area of ​​the carbon anode materials prepared in Examples 1-3 is ≤1.7m². 2 / g, tap density ≥1.1g / cm³ 3 Furthermore, lithium-ion batteries assembled from it exhibit superior first-discharge specific capacity and first-coulombic efficiency.

[0138] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A carbon anode material precursor, characterized in that, The carbon anode material precursor includes: a first needle-shaped coke (a1, k1), a second needle-shaped coke (a2, k2), and a third needle-shaped coke (a3, k3), wherein a1, a2, and a3 represent the total content of large sheet and fibrous structures in the anisotropic structure of the coke particles, respectively; and k1, k2, and k3 represent the aspect ratio of the coke particles, respectively. The weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 10-20:60-70:15-25; the first needle coke satisfies: 70%≤a1<80%, and 1.68≤k1<1.78; the second needle coke satisfies: 80%≤a2<90%, and 1.78≤k2<1.85; the third needle coke satisfies: 90%≤a3<100%, and 1.85≤k3<1.

95.

2. The carbon anode material precursor according to claim 1, wherein, The weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 12-18:62-68:16-24.

3. The application of the carbon anode material precursor according to claim 1 or 2 in carbon anode materials.

4. A carbon anode material, characterized in that, The carbon anode material includes: the carbon anode material precursor as described in claim 1 or 2, and asphalt coating.

5. The carbon anode material according to claim 4, wherein, Based on the total weight of the carbon anode material, the content of the carbon anode material precursor is 80-95 wt%; the content of the coated asphalt is 5-20 wt%.

6. The carbon anode material according to claim 5, wherein, Based on the total weight of the carbon anode material, the content of the carbon anode material precursor is 85-90 wt%; and the content of the coated asphalt is 10-15 wt%.

7. The carbon anode material according to claim 4, wherein, The coated asphalt is obtained by graphitizing high-temperature asphalt.

8. The carbon anode material according to claim 7, wherein, The softening point of the high-temperature asphalt is 105-120℃, and the quinoline insoluble content of the high-temperature asphalt is ≤0.2wt%.

9. The carbon anode material according to any one of claims 4-8, wherein, The specific surface area of ​​the carbon anode material is ≤2m². 2 / g; tap density ≥1g / cm³ 3 .

10. A method for preparing the carbon anode material according to any one of claims 4-9, characterized in that, The preparation method includes the following steps: (1) The first needle coke (a1, k1), the second needle coke (a2, k2) and the third needle coke (a3, k3) are mixed to obtain a carbon anode material precursor; wherein a1, a2 and a3 represent the total content of large sheet and fiber structure in the anisotropic structure of the coke particles, respectively; k1, k2 and k3 represent the aspect ratio of the coke particles, respectively; wherein a1≠a2≠a3 and k1≠k2≠k3; (2) The carbon anode material precursor and high-temperature asphalt are coated to obtain a coated product; (3) The coated product is graphitized in a non-oxidizing atmosphere to obtain a carbon anode material; The weight ratio of the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) is 10-20:60-70:15-25.

11. The preparation method according to claim 10, wherein, In step (1), the mixing process includes: (1-1) mixing the first needle coke (a1, k1) and the second needle coke (a2, k2) to obtain a first mixture; (1-2) mixing the first mixture with the third needle coke (a3, k3).

12. The preparation method according to claim 11, wherein, In steps (1-2), a portion of the first mixture and the third needle coke (a3, k3) are first mixed, and then the remaining portion of the first mixture is added and mixed. The weight ratio of the portion of the first mixture to the first mixture is 1-2:

3. And / or, prior to the mixing, the first needle coke (a1, k1), the second needle coke (a2, k2), and the third needle coke (a3, k3) are each independently and sequentially crushed and sieved, and the D50 of the crushed and sieved first needle coke (a1, k1), second needle coke (a2, k2), and third needle coke (a3, k3) is each independently 10-20µm.

13. The preparation method according to any one of claims 10-12, wherein, In step (2), the weight ratio of the carbon anode material precursor to the high-temperature asphalt is 80-95:5-20.

14. The preparation method according to claim 13, wherein, In step (2), the weight ratio of the carbon anode material precursor to the high-temperature asphalt is 85-90:10-15.

15. The preparation method according to any one of claims 10-12, wherein, The softening point of the high-temperature asphalt is 105-120℃, and the viscosity is ≤40 mm. 2 / s.

16. The preparation method according to claim 15, wherein, The high-temperature asphalt is a high-temperature petroleum asphalt with a softening point of 105-120℃ and a quinoline insoluble content of ≤0.2wt%.

17. The preparation method according to any one of claims 10-12, wherein, The coating process includes: a first coating stage, a second coating stage, and a third coating stage; wherein... The conditions for the first coating stage include: heating to 180-260°C at a heating rate of 2-8°C / min; time of 1-4 hours; and rotation speed of 200-500 rpm. The conditions for the second coating stage include: cooling to 10-15°C above the softening point of the high-temperature asphalt at a cooling rate of 2-8°C / min; and rotating at a speed of 100-300 rpm. The third coating stage includes cooling to 25°C at a cooling rate of 5-10°C / min.

18. The preparation method according to claim 17, wherein, The conditions for the first coating stage include: heating to 200-240°C at a heating rate of 2-8°C / min; time of 2-3 hours; and rotation speed of 300-400 rpm. And / or, the conditions for the second coating stage include: a rotational speed of 150-250 rpm.

19. The preparation method according to any one of claims 10-12, wherein, In step (3), the graphitization treatment conditions include: a first graphitization stage and a second graphitization stage; wherein, The conditions for the first graphitization stage include: heating to 1000-1500℃ at a heating rate of 1-10℃ / min; and a time of 8-18h. The conditions for the second graphitization stage include: heating to 2500-3500℃ at a heating rate of 1-10℃ / min; and a time of 15-30h. And / or, the method further includes: sieving the graphitized product to obtain the carbon anode material.

20. The preparation method according to claim 19, wherein, The conditions for the first graphitization stage include: heating to 1100-1300℃ at a heating rate of 1-10℃ / min; and a time of 10-15h. And / or, the conditions for the second graphitization stage include: heating to 2800-3000°C at a heating rate of 1-10°C / min for 15-24 hours.

21. The application of the carbon anode material according to any one of claims 4-9 in lithium-ion batteries.

22. A lithium-ion battery, characterized in that, The lithium-ion battery includes: the carbon anode material according to any one of claims 4-9.

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