Negative electrode material and battery

Abstract

The present application provides a negative electrode material and a battery. The negative electrode material includes artificial graphite particles, the artificial graphite particles having pores inside and / or on the surface thereof, and a pore volume of the negative electrode material is V cm 3 / kg, and true density is D g / cm 3 , the specific surface area is S m 2 / g, 4.0≦V×S / D≦10. The negative electrode material and the battery provided by the present application can efficiently increase the active sites on the surface of the negative electrode material, and improve the rate characteristics of the negative electrode material.

Description

[Technical Field]

[0001] This application relates to the technical field of negative electrode materials. More specifically, to negative electrode materials and batteries. [Background technology]

[0002] Graphite has several advantages, including high electrical conductivity, a large lithium-ion diffusion coefficient, minimal volume change before and after lithium absorption in its layered structure, high lithium absorption capacity, and a low lithium absorption potential. For these reasons, it is currently the dominant negative electrode material in commercially available lithium-ion batteries.

[0003] Conventional graphite anode graphitization equipment mainly consists of two types: crucible furnaces and box furnaces. Both are batch-type operations, and continuous production is not possible because power outages are required during the graphitization process. Furthermore, the heating and cooling processes of the equipment are particularly limited, and the heating and cooling rates are slow, resulting in long production cycles. Generally, the graphitization cycle is within 15 to 50 days. During the graphitization production process, volatile components and impurity elements in the raw materials escape under high-temperature conditions, forming pores inside and / or on the surface of the graphite. Generally, all artificial graphite has a certain number of pore structures. The presence of pores increases the diffusion channels for Li+ within the graphite material and reduces the diffusion resistance of Li+, thereby effectively improving the rate characteristics of the material. However, too many pore structures lead to an increase in the specific surface area of ​​the material, further degrading the initial efficiency and cycle performance of the product. In reality, simply improving the pore structure is not enough to achieve optimal rate characteristics, and there is still considerable room for improvement. Researchers have limited their studies to the effect of a single element on the performance of graphite materials, and have not delved deeply into the synergistic effects between multiple elements in order to maximize the improvement of graphite's rate properties.

[0004] Therefore, at this mature stage in the development of graphite materials, improving a single parameter will not satisfy the market demand for low-cost, high-performance graphite materials. It is necessary to study the synergistic mechanisms of various factors and develop graphite anode materials that meet market demands.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In view of the above, the present application provides a new negative electrode material and a battery that realize accurate adjustment and control of the internal and / or surface pore volume, specific surface area, and true density, and maintain them within a reasonable range in combination, thereby improving the capacity and rate characteristics of the negative electrode material, to address the drawbacks of the prior art.

Means for Solving the Problems

[0006] In a first aspect, the present application provides a negative electrode material, wherein the negative electrode material includes artificial graphite, the artificial graphite has pores, and when the pore volume of the negative electrode material is V cm 3 / kg, the true density is D g / cm 3 and the specific surface area is S m 2 / g, 4.0 ≦ V × S / D ≦ 10. The pore volume is measured using an ASAP 2460 device manufactured by Micromeritics, USA, and calculated within a pore diameter range of 17 Å to 3000 Å using the BJH Desorption cumulative volume of pores model.

[0007] In some embodiments, the particle size D 50 of the negative electrode material is 10 μm to 30 μm.

[0008] In some embodiments, the particle size D 10 of the negative electrode material is ≧ 5 μm.

[0009] In some embodiments, the particle size D 90 of the negative electrode material is ≦ 50 μm.

[0010] In some embodiments, when the pore volume of the negative electrode material is V cm 3 / kg, 5 ≦ V ≦ 8.

[0011] In some embodiments, when the specific surface area of the negative electrode material is S m 2 / g, 1.78 ≤ S ≤ 3.0.

[0012] In some embodiments, when the true density of the negative electrode material is D g / cm 3 , 2.210 ≤ D ≤ 2.265.

[0013] In some embodiments, the pores include at least one of micropores and mesopores.

[0014] In some embodiments, the pores have an average pore diameter of 50 Å to 200 Å.

[0015] In some embodiments, after X-ray diffraction measurement, the interlayer distance of the crystal plane of the (002) plane of the negative electrode material is d 002 , 3.355 Å ≤ d 002 ≤ 3.365 Å.

[0016] In some embodiments, by X-ray diffraction measurement, the peak intensity ratio I 002 / I 110 of the (002) plane and the (110) plane of the artificial graphite particles is 65.0 to 120.0, and the peak intensity ratio I 004 / I 110 of the (004) plane and the (110) plane is 3.0 to 6.0.

[0017] In some embodiments, the artificial graphite includes artificial graphite primary particles and / or artificial graphite secondary particles.

[0018] In some embodiments, the negative electrode material further includes amorphous carbon.

[0019] In some embodiments, the negative electrode material further includes amorphous carbon, and the mass ratio of the amorphous carbon in the negative electrode material is 0.1 wt% to 5 wt%.

[0020] According to a second aspect, the present application provides a battery comprising the negative electrode material described in the first aspect. [Effects of the Invention]

[0021] The technical means of this application has at least the following beneficial effects. The negative electrode material provided in this application comprises artificial graphite, has pores inside and / or on the surface of the artificial graphite, and the pore volume of the negative electrode material is V cm 3 The true density is D g / cm³ / kg. 3 The specific surface area is S m 2 When expressed in units of g, 4.0 ≤ V × S / D ≤ 10. Generally, a certain range of pore volume in artificial graphite can increase the diffusion channels for Li ions, and a certain range of specific surface area ensures a sufficient electrochemical reaction interface, promoting the diffusion of lithium ions at the solid-liquid interface and within the solid phase, reducing concentration polarization, and is advantageous for improving the capacity and rate characteristics of the negative electrode material. Based on this, the applicant conducted diligent research and found that after lithium ions diffuse onto the surface of artificial graphite, if the order of carbon atoms in the artificial graphite is relatively disordered and the degree of order is insufficient, the inhibition of lithium ions entering the interior of the artificial graphite material, bonding with carbon atoms, and generating an electrochemical reaction is relatively large, the diffusion channels and electrochemical reaction area are not fully utilized, and since the degree of order and true density of artificial graphite are directly related, only the lithium ion diffusion channels and electrochemical reaction area are sufficiently present, and there is still considerable room for improvement in the rate characteristics. This invention is advantageous for bonding lithium ions and a sufficient number of carbon atoms with low resistance by controlling the V×S / D ratio of the negative electrode material within the above range, thereby obtaining a negative electrode material with superior rate characteristics and capacity.

[0022] The negative electrode material provided in this application is produced and processed by a continuous graphitization process, in which all materials are continuously loaded and discharged, and the time and temperature of passage through the high-temperature region are matched. Furthermore, by controlling the heating and cooling rates during the graphitization process, volatile components, impurity elements, and other substances within the material can be uniformly and rapidly removed. At the same time, the press molding dimensions are controlled, a fixed amount of additives is introduced, and precise control of the pore volume inside and / or on the surface of the graphite is achieved. By synergistically using the above process method, problems such as uneven heating of the material due to temperature gradients at different locations in the conventional graphitization furnace, and large, uncontrolled fluctuations in indicators such as specific surface area, pore volume, and true density of the processed product are overcome, thereby enabling the pore volume, specific surface area, and true density of the processed material to reach the ideal adjustment and control design requirements.

[0023] The negative electrode material provided in this application utilizes a continuous graphitization process, resulting in low energy consumption per unit mass, significant advantages in cost and production cycle, and environmental friendliness. [Brief explanation of the drawing]

[0024] [Figure 1] This is a scanning electron microscope image of the negative electrode material manufactured in Example 12 of this application. [Figure 2] This is the pore size distribution curve of the negative electrode material manufactured in Example 12 of this application. [Modes for carrying out the invention]

[0025] To better explain this application and facilitate understanding of its technical proposal, the application will be described in further detail below. Note that the following embodiments are merely simplified examples of the application and do not indicate or limit the scope of protection provided for this application.

[0026] In the field of anode materials, development of continuous graphitization equipment has continued for several decades. As early as 1987, a patent (US06619591) disclosed equipment capable of continuous graphitization treatment of carbon-containing materials. In recent years, the applicant has also continued to develop continuous graphitization equipment. For example, a patent filed in 2019, registration publication number CN211425033U, discloses a vertical continuous lithium battery anode material production kiln that can continuously discharge material from an outlet and continuously load material from a material piping. Compared to conventional processes, the continuous graphitization process reduces the graphitization time from several days to several hours and significantly reduces energy consumption. Furthermore, the drastically reduced graphitization time allows for changes in the microstructure of artificial graphite, particularly changes in the pore structure and crystal form within the artificial graphite, compared to conventional artificial graphite. The industry has long verified that such changes make it difficult to meet the performance requirements of artificial graphite and are difficult to improve. Therefore, even though continuous graphitization equipment has existed for 30 to 40 years, there is no precedent for successful mass production of continuously graphitized artificial graphite anode products.

[0027] In recent years, with the increasing energy constraints, the applicant has continued development for applications in continuous graphitization equipment to further reduce the cost of artificial graphite. The aim is to develop artificial graphite anode materials that are equivalent to, or even better than, current conventional graphitization anode materials in terms of performance, thereby reducing the energy consumption of artificial graphite anode materials and further lowering costs. Through the development of large-scale preparation processes, the applicant has developed various means to improve the rapid temperature rise and fall that causes unfavorable changes in artificial graphite products, and by selecting products, has obtained a series of different types of artificial graphite anode materials. Although the microstructure of these artificial graphite anode materials differs from that of conventional artificial graphite products, their electrical performance can be basically equivalent to that of conventional artificial graphite products, and furthermore, their electrical performance and processing performance in certain aspects are superior or more stable, providing a suitable alternative to conventional artificial graphite products.

[0028] The following describes in more detail the manufacturing process developed by the applicant and the related products, using the process as an example.

[0029] The method for manufacturing the negative electrode material is: S10: A mixture containing coke powder, binder, additives and solvent is press-molded to obtain a first precursor, where the additives include inorganic compounds, the mass ratio of coke powder to additives is 100:(1~5), and the press dimensions are φ(10mm~100mm)×(20mm~100mm). S20: A step of obtaining a second precursor by pre-carbonizing the first precursor, S30: The second precursor is placed in a continuous graphitization furnace and heated to 2800°C to 3200°C at a heating rate of 13°C / min to 20°C / min for 1 to 4 hours to perform graphitization. After that, the temperature is lowered at a cooling rate of 20°C / min to 25°C / min to obtain the negative electrode material. This step includes controlling the ratio of the heating rate to the cooling rate to 0.5 to 1.

[0030] The method for manufacturing a negative electrode material provided in this application involves press-molding a mixture of coke powder, binder, additives, and solvent, pre-carbonizing the first precursor, and then placing it in a continuous graphitization furnace. This allows for an extremely fast heating rate, enabling the second precursor to reach the graphitization temperature in a relatively short time after rapid heating. The additives volatilize and escape, forming pores inside and / or on the surface of the graphite particles. These pores can serve as additional lithium storage spaces, improving the lithium storage capacity of the graphite material. Furthermore, the process of introducing and discharging the material into the continuous graphitization furnace is completed within just a few hours, resulting in a high thermal energy utilization rate and reduced production costs.

[0031] Coke powder is obtained by grinding and shaping coke raw materials, and the coke raw materials include at least one of petroleum coke, needle coke, pitch coke, and isotropic coke.

[0032] In some embodiments, shaping includes at least one of crushing, spheroidizing, or classifying. The median diameter of the shaped coke powder is 15 μm to 20 μm, more specifically 15 μm, 15.5 μm, 16 μm, 16.5 μm, 17 μm, 17.5 μm, 18 μm, 18.5 μm, 19 μm, or 20 μm, but is not limited to the values ​​listed, and other unlisted values ​​within that range are also applicable. Controlling the median diameter of the coke powder within the above range through multiple tests is advantageous for achieving both processing performance, volume, and rate characteristics.

[0033] In some embodiments, the mass carbon content in the coke powder is 80% or more, specifically 80%, 81%, 82%, 85%, 90%, 95%, or 96%, but is not limited to these values, and other unlisted values ​​within that range are also applicable.

[0034] In some embodiments, the solvent includes at least one of water, ethanol, acetone, benzene, toluene, quinoline, tetrahydrofuran, and carbon tetrachloride.

[0035] In some embodiments, the binder includes at least one of petroleum resin, phenolic resin, epoxy resin, coumarone resin, potato starch, wheat starch, corn starch, sweet potato starch, kudzu starch, and tapioca starch.

[0036] In some embodiments, the additive comprises at least one of boron oxide, boron carbide, boron nitride, silicon carbide, boron nitride, boric acid, boron chloride, and sodium borate, and the additive acts as a graphitization catalyst while volatilizing and escaping due to rapid temperature increases and decreases during the graphitization process, which is advantageous for forming stable pores inside and / or on the surface of the artificial graphite.

[0037] In some embodiments, the mass ratio of coke powder, binder, solvent, and additives is 100:(3~20):(5~50):(1~5), specifically 100:3:5:1, 100:10:15:1, 100:15:20:5, 100:20:20:1, 100:20:15:3, 100:10:10:5, or 100:15:25:2, but is not limited to the values ​​listed, and other unlisted values ​​within that range are also applicable. Controlling the additive content within the above range is advantageous for the occurrence of the catalytic graphitization process, while the additives may volatilize at high temperatures to form a certain number of pores inside and / or on the surface of the graphite.

[0038] To make it clear, in the examples, when the proportion of binder is low (the mass ratio of binder to coke powder is 3 to 10:100), the resulting artificial graphite mainly consists of primary particles, and in the examples, when the proportion of binder is high (the mass ratio of binder to coke powder is 10 to 20:100), the resulting artificial graphite mainly consists of secondary particles.

[0039] In some embodiments, the mixing method of the mixture includes at least one of mechanical stirring and ultrasonic dispersion. When mechanical stirring is used for mixing, propeller-type stirrers, turbine-type stirrers, flat-blade stirrers, etc., can be used as long as each component in the mixture is sufficiently and uniformly mixed.

[0040] In some embodiments, the stirring speed is 10 r / min to 1000 r / min, and may specifically be, but is not limited to, 10 r / min, 50 r / min, 70 r / min, 100 r / min, 120 r / min, 150 r / min, 200 r / min, 300 r / min, 350 r / min, 400 r / min, 500 r / min, or 1000 r / min. Controlling the stirring speed within the above range is advantageous for mixing each component to form a homogeneous mixture.

[0041] Stirring may be carried out at room temperature or under preheating conditions, and preferably the stirring temperature may be controlled to 25°C to 200°C. As can be understood, appropriate preheating is advantageous for mixing the components to form a homogeneous mixture.

[0042] In some embodiments, the press forming method includes at least one of extrusion, die pressing, roll pressing, and isostatic pressing.

[0043] In some embodiments, the press forming pressure is 5 MPa to 100 MPa, specifically 5 MPa, 15 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 55 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, or 100 MPa. The press forming process can improve the fluidity of the material during the graphitization process, while also improving the amount of material charged into the furnace and the production capacity.

[0044] Controlling the press forming dimensions to φ(10mm~100mm)×(20mm~100mm) during press forming is advantageous for controlling the specific surface area, as well as for the loading and unloading of the graphitization process.

[0045] In some embodiments, the reaction temperature for the pre-carbonization treatment is 500°C to 1000°C, specifically 500°C, 550°C, 600°C, 700°C, 750°C, 800°C, 850°C, 900°C, or 1000°C, but is not limited to these values, and other unlisted values ​​within that range are also applicable. As can be understood, having the pre-carbonization treatment temperature within the above range is advantageous for the emission of volatile components and other substances from the coke raw material.

[0046] In some embodiments, the heat retention time for the pre-carbonization treatment is 1 to 10 hours, specifically 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or 10 hours, but is not limited to the values ​​listed, and other values ​​within that range that are not listed are also applicable. Preferably, the heat retention time for the pre-carbonization treatment is 1 to 4 hours.

[0047] In some embodiments, the heating rate of the pre-carbonization treatment is 5°C / min to 20°C / min, and specifically, it may be 5°C / min, 6°C / min, 8°C / min, 10°C / min, 15°C / min, 15.5°C / min, or 20°C / min, but is not limited to the values ​​listed, and other values ​​within that range that are not listed are also applicable.

[0048] In some embodiments, the cooling rate after pre-carbonization treatment is 10°C / min to 30°C / min, and specifically may be 10°C / min, 15°C / min, 20°C / min, 25°C / min, 25.5°C / min, or 30°C / min, but is not limited to the values ​​listed above, and other values ​​within that range that are not listed are also applicable.

[0049] In some embodiments, the pre-carbonization treatment is carried out in a protective atmosphere containing at least one of nitrogen gas, helium gas, neon gas, argon gas, krypton gas, and xenon gas.

[0050] In some embodiments, the heating rate for the graphitization treatment may be 13°C / min, 15°C / min, 17°C / min, 18°C / min, or 20°C / min, and the cooling rate after the graphitization treatment may be 20°C / min, 21°C / min, 22°C / min, 23°C / min, 24°C / min, or 25°C / min.

[0051] In some embodiments, the structure of a continuous graphitization furnace is shown in patent CN211425033U.

[0052] In some embodiments, the graphitization process involves heating to 2800°C to 3200°C at a heating rate of 13°C / min to 20°C / min, followed by holding the temperature at 2800°C to 3200°C for 2 to 4 hours. As can be seen, the rapid heating in the graphitization process is advantageous for rapidly releasing volatile components from within the coke raw material and for forming pores in the product.

[0053] In some embodiments, the graphitization temperature may be, specifically, 2800°C, 2850°C, 2900°C, 3000°C, 3100°C, 3150°C, 3180°C, or 3200°C, but is not limited to the values ​​listed above, and other unlisted values ​​within that range are also applicable.

[0054] In some embodiments, the holding time for the graphitization treatment is 1 to 4 hours, specifically 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 3.8 hours, or 4 hours, but is not limited to the values ​​listed, and other values ​​within that range that are not listed are also applicable. Preferably, the holding time for the graphitization treatment is 2 to 3 hours.

[0055] In some embodiments, the cooling rate after graphitization is 20°C / min to 25°C / min, specifically 20°C / min, 21°C / min, 22°C / min, 23°C / min, 24°C / min, or 25°C / min, but is not limited to the values ​​listed, and other values ​​within that range that are not listed are also applicable. Rapid cooling can reduce the occurrence of material oxidation reactions during the cooling process, which is advantageous for controlling the specific surface area of ​​the material, while also significantly shortening the graphitization cycle and reducing production costs.

[0056] In some embodiments, the ratio of the heating rate to the cooling rate in the graphitization process may be 0.5, 0.6, 0.7, 0.8, 0.9, or 1.0. Controlling this ratio is advantageous for releasing volatile substances from within the material and for maintaining the product of the material's pore volume and specific surface area at a relatively constant value.

[0057] To make it easier to understand, after the adhesive is graphitized, some of it is difficult to convert to graphitized carbon, and the parts that cannot be converted to graphitized carbon exist on the surface of the artificial graphite particles in the form of amorphous carbon.

[0058] In some embodiments, the graphitization treatment is followed by at least one of crushing, sieving, and demagnetization. Preferably, the carbonization treatment is followed by crushing, demagnetization, and sieving in that order.

[0059] In some embodiments, the grinding means may be one of a mechanical grinder, an air-jet grinder, and a cryogenic grinder.

[0060] In some embodiments, the sieving method is one of the following: a fixed sieve, a drum screen, a resonant sieve, a roller sieve, a vibrating sieve, and a chain grizzly. The number of meshes used for sieving is 100 to 500 meshes, and specifically, the number of meshes used for sieving may be 100 meshes, 200 meshes, 250 meshes, 325 meshes, 400 meshes, 500 meshes, etc. Controlling the particle size of the negative electrode material within the above range contributes to improving the processing characteristics of the negative electrode material.

[0061] In some embodiments, the demagnetizer is one of a permanent magnet drum-type magnetic separator, an electromagnetic iron remover, and a pulsating high-gradient magnetic separator, and the demagnetization is ultimately to control the content of magnetic material in the negative electrode material, to avoid the discharge effect of magnetic material on the battery, and to ensure the safety of the battery during use.

[0062] A negative electrode material comprising artificial graphite, having pores inside and / or on the surface of the artificial graphite, with a pore volume of V cm². 3 The true density is D g / cm³ / kg. 3 The specific surface area is S m 2When expressed as / g, 4.0 ≤ V × S / D ≤ 10. The pore volume was measured using an ASAP 2460 instrument manufactured by Micromerities, Inc., USA, and calculated within the pore diameter range of 17 Å to 3000 Å using the BJH Desorption cumulative volume of pores model.

[0063] The negative electrode material provided in this application is manufactured by a continuous graphitization process. By matching the time and temperature at which all materials pass through the high-temperature region and controlling the heating and cooling rates, volatile components, impurity elements, and other substances within the material can be uniformly and rapidly removed. Simultaneously, by introducing a certain amount of additives, precise control of pores in the graphite and / or on the surface is achieved, bringing the pore volume, specific surface area, and true density of the material to ideally match the design requirements. Pores are formed in the graphite and / or on the surface, and these pores can serve as additional lithium storage space, improving the lithium storage capacity of the negative electrode material and increasing the specific surface area. When the negative electrode material is manufactured as an electrode and applied to a battery, after the electrolyte is injected, the pores inside the artificial graphite particles are filled with the electrolyte. During charging and discharging, an electrochemical reaction occurs inside the electrode, and the pores create more lithium ion diffusion channels and electrochemical reaction interfaces in the negative electrode material. This promotes the diffusion of lithium ions at the solid-liquid interface and within the solid phase, reduces concentration polarization, and is advantageous for improving the capacity and rate characteristics of the negative electrode material.

[0064] Generally, a certain range of pore volume in artificial graphite can increase the diffusion channels for Li ions, and a certain range of specific surface area can ensure a sufficient electrochemical reaction interface. This promotes the diffusion of lithium ions at the solid-liquid interface and within the solid phase, reduces concentration polarization, and is advantageous for improving the capacity and rate characteristics of the anode material. Based on this, the applicant conducted diligent research and found that after lithium ions diffuse onto the surface of artificial graphite, if the order of carbon atoms in the artificial graphite is relatively disordered and the degree of order is insufficient, the inhibition of lithium ions entering the interior of the artificial graphite material, bonding with carbon atoms, and generating electrochemical reactions is relatively large. The diffusion channels and electrochemical reaction area are not fully utilized, and since the order and true density of the artificial graphite are directly related, even if sufficient lithium ion diffusion channels and electrochemical reaction area are present, there is still considerable room for improvement in rate characteristics. This application aims to obtain an anode material with superior rate characteristics and capacity by controlling the V×S / D of the anode material within the above range, which is advantageous for bonding lithium ions with sufficient carbon atoms at low resistance.

[0065] In some embodiments, the particle size D of the negative electrode material 50 The median diameter of the negative electrode material is between 10 μm and 30 μm. Specifically, it may be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 20 μm, 25 μm, or 30 μm, and is not limited thereto. Controlling the median diameter of the negative electrode material within the above range is advantageous for improving the cycle performance of the negative electrode material.

[0066] Note D 10 This represents the particle size corresponding to the point when the percentage of the cumulative particle size distribution of the powder reaches 10%, and D 50 This represents the particle size corresponding to the point when the cumulative particle size distribution percentage reaches 50%, and D 90 This represents the particle size corresponding to the point when the cumulative particle size distribution percentage reaches 90%.

[0067] In some embodiments, the particle size D of the negative electrode material 10 The size is ≥ 5 μm, and specifically, it may be 5 μm, 5.5 μm, 6 μm, 7 μm, 8 μm, or 10 μm, etc., and is not limited thereto.

[0068] In some embodiments, the particle size D of the negative electrode material 90 The size is ≤50 μm, and specifically, it may be 50 μm, 49 μm, 48 μm, 47 μm, 46 μm, 45 μm, 42 μm, or 40 μm, etc., and is not limited thereto.

[0069] In some embodiments, the pore volume of the negative electrode material is set to V cm 3 When expressed in kg, 5 ≤ V ≤ 8, and specifically, it may be 5, 5.2, 5.5, 5.8, 6.0, 6.2, 6.5, 6.8, 7.0, 7.5, or 8.0, etc., and is not limited to these values.

[0070] In some embodiments, the specific surface area of ​​the negative electrode material is set to S m 2 When expressed in units of g, 1.78 ≤ S ≤ 3.0, and specifically, it may be 1.78, 1.85, 1.95, 2.00, 2.25, 2.43, 2.57, 2.61, 2.72, 2.85, or 3.0, etc., and is not limited thereto. To make it clear, if the specific surface area is too large, it is more likely to lead to the formation of a solid electrolyte film, which causes excessive consumption of irreversible lithium salt and reduces the initial efficiency of the battery.

[0071] In some embodiments, the true density of the negative electrode material is D g / cm³. 3 In this case, 2.210 ≤ D ≤ 2.265, and specifically, it may be 2.210, 2.215, 2.218, 2.220, 2.252, 2.263, 2.260, or 2.265, etc., and is not limited here.

[0072] In some embodiments, the pores include at least one of micropores and mesopores.

[0073] In some embodiments, the average pore diameter is 50 Å to 200 Å. Specifically, the average pore diameter may be 50 Å, 51 Å, 52 Å, 52.5 Å, 53.8 Å, 56.7 Å, 60 Å, 70 Å, 100 Å, 150 Å, or 200 Å, etc.

[0074] In some embodiments, the negative electrode material is determined by X-ray diffraction measurement to determine the interlayer distance of the (002) crystal planes d 002 When this is done, 3.355 Å ≤ d 002 The interlayer distance d of the crystal plane is ≤3.365 Å. 002 Since the values ​​fall within the above range, it can be seen that the artificial graphite particles have a high degree of graphitic crystallinity, i.e., a high degree of graphitization, and therefore a high product volume.

[0075] In some embodiments, X-ray diffraction tests determine the peak intensity ratio of the (002) plane and the (110) plane of the artificial graphite particles. 002 / I 110 The range is 65.0 to 120.0, and the peak intensity ratio of the (004) plane and the (110) plane is I 004 / I 110 It is 3.0 to 6.0. 002 / I 110 and I 004 / I 110 If it falls within this range, the degree of material orientation is relatively high, and cycle expansion is low. 002 / I 110 The ratio may be, specifically, 65.0, 70.0, 75.0, 80.0, 85.3, 89.2, 90.5, 95.1, 100.0, 111.0, or 120.0, and is not limited thereto. 004 / I 110 The ratio may be, specifically, 3.0, 3.2, 3.5, 3.8, 4.1, 4.2, 4.5, 5.2, 5.8, 5.9, or 6.0, and is not limited thereto.

[0076] In some embodiments, the artificial graphite comprises primary and / or secondary particles of artificial graphite.

[0077] In some embodiments, the anode material further contains amorphous carbon, with the mass ratio of amorphous carbon in the anode material being 0.1 wt% to 5 wt%. The presence of amorphous carbon provides lithium ions with more irregular and open diffusion pathways, which is advantageous for improving the material rate properties.

[0078] In some embodiments, the specific capacity of the negative electrode material is 320 mAh / g to 370 mAh / g, and may specifically be 320 mAh / g, 340 mAh / g, 342 mAh / g, 345 mAh / g, 353 mAh / g, 355 mAh / g, 357 mAh / g, 360 mAh / g, 365 mAh / g, or 370 mAh / g, and is not limited thereto. Preferably, the specific capacity of the negative electrode material is 340 mAh / g to 370 mAh / g.

[0079] A battery containing the above-mentioned negative electrode material.

[0080] As will be apparent to those skilled in the art, the battery manufacturing methods described above are merely examples. Other methods commonly used in the art may be employed without departing from the scope of disclosure in this application, and other types of batteries, such as sodium-ion batteries and potassium-ion batteries, may be manufactured and measured. [Examples]

[0081] The embodiments of this application will be further described below with reference to several examples. However, the embodiments of this application are not limited to the following specific examples. Appropriate modifications can be made within the scope of protection.

[0082] Example 1 The method for manufacturing the negative electrode material in this embodiment is: (1) A step in which the raw coke raw material of Taikei Petroleum Coke is crushed, shaped using a shaping device to obtain crushed and shaped coke powder, and the median diameter is controlled to 15 μm, (2) A step of uniformly mixing coke powder, phenol resin binder, water, and boron oxide in a mass ratio of 100:6:15:2 to obtain a mixture, (3) The mixture is press-molded at a pressure of 10 MPa to obtain a first precursor, and the size of the first precursor after press-molding is φ30 mm × 50 mm. (4) The first precursor is pre-carbonized at a temperature of 800°C for 4 hours, and then cooled to obtain the modified second precursor. (5) The second precursor was graphitized in a continuous graphitization furnace at 2900°C to obtain the graphitized product. The heating curve involved heating to 2900°C at a heating rate of 15.5°C / min, holding at 2900°C for 2.5 hours, and then cooling to 30°C at a cooling rate of 22.5°C / min after holding, controlling the heating and cooling rate ratio in the graphitization process to 0.68. (6) The process includes dispersing, demagnetizing, and sieving the graphitized material through a 325-mesh sieve to obtain a negative electrode material.

[0083] The above-mentioned negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0084] Example 2 The method for manufacturing the negative electrode material in this embodiment is: (1) A step in which the raw coke raw material of Bao Steel pitch coke is crushed and shaped in a shaping device to obtain coke powder after crushing and shaping, and the median diameter is controlled to 16 μm, (2) A step of uniformly mixing coke powder, petroleum resin, benzene, and boron carbide in a mass ratio of 100:5:20:2 to obtain a mixture, (3) The mixture is press-molded at a pressure of 10 MPa to obtain a first precursor, and the size of the first precursor after press-molding is φ30 mm × 50 mm. (4) The first precursor is pre-carbonized at a temperature of 800°C for 4 hours, and then cooled to obtain the modified second precursor. (5) The second precursor was graphitized in a continuous graphitization furnace at 2900°C to obtain the graphitized product. The heating curve involved heating to 2900°C at a heating rate of 14°C / min, holding at 2900°C for 2.5 hours, and then cooling to 30°C at a cooling rate of 22.5°C / min, controlling the heating and cooling rate ratio in the graphitization process to 0.62. (6) The process includes dispersing, demagnetizing, and sieving the graphitized product through a 250-mesh sieve to obtain a negative electrode material.

[0085] The above-mentioned negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0086] Example 3 The method for manufacturing the negative electrode material in this embodiment is: (1) A step in which mature coke raw material of Jinzhou needle coke is crushed and shaped in a shaping device to obtain crushed and shaped coke powder, and the median diameter is controlled to 15 μm, (2) A step of uniformly mixing coke powder, phenol resin binder, water, and boron oxide in a mass ratio of 100:6:15:2 to obtain a mixture, (3) The mixture is press-molded at a pressure of 10 MPa to obtain a first precursor, and the size of the first precursor after press-molding is φ30 mm × 50 mm. (4) The first precursor is pre-carbonized at a temperature of 800°C for 4 hours, and then cooled to obtain the modified second precursor. (5) The second precursor was graphitized in a continuous graphitization furnace at 2850°C to obtain the graphitized product. The heating curve involved heating to 2850°C at a heating rate of 16°C / min, holding at 2850°C for 2.5 hours, and then cooling to 30°C at a cooling rate of 22°C / min, controlling the heating / cooling rate ratio in the graphitization process to 0.73. (6) The process includes dispersing, demagnetizing, and sieving the graphitized product through a 250-mesh sieve to obtain a negative electrode material.

[0087] The above-mentioned negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0088] Example 4 The method for manufacturing the negative electrode material in this embodiment is: (1) The raw coke raw material of Kyoyo Needle Coke is crushed and shaped using a shaping device to obtain crushed and shaped coke powder, and the median diameter is controlled to 18 μm. (2) A step of uniformly mixing coke powder, petroleum resin, benzene, and sodium borate in a mass ratio of 100:6:15:2 to obtain a mixture, (3) The mixture is press-molded at a pressure of 10 MPa to obtain a first precursor, and the size of the first precursor after press-molding is φ30 mm × 50 mm. (4) The precursor is pre-carbonized at a temperature of 800°C for 4 hours, and then cooled to obtain a modified second precursor. (5) The second precursor was graphitized in a continuous graphitization furnace at 2850°C to obtain the graphitized product. The heating curve involved heating to 2850°C at a heating rate of 16.5°C / min, holding at 2850°C for 3 hours, and then cooling to 30°C at a cooling rate of 22°C / min, controlling the heating and cooling rate ratio in the graphitization process to 0.75. (6) The process includes dispersing, demagnetizing, and sieving the graphitized product through a 250-mesh sieve to obtain a negative electrode material.

[0089] The above-mentioned negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0090] Example 5 The only difference from Example 1 is that in step (2), coke powder, epoxy resin, water, and boron oxide are uniformly mixed in a mass ratio of 100:6:15:2 to obtain the mixture.

[0091] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0092] Example 6 The only difference from Example 1 is that in step (2), coke powder, coumarone resin, water, and boron oxide are uniformly mixed in a mass ratio of 100:5:15:2 to obtain the mixture.

[0093] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0094] Example 7 The only difference from Example 1 is that in step (2), coke powder, epoxy resin, water, and boron nitride are uniformly mixed in a mass ratio of 100:6:15:2 to obtain the mixture.

[0095] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0096] Example 8 The only difference from Example 1 is that in step (2), coke powder, petroleum resin, toluene, and boric acid are uniformly mixed in a mass ratio of 100:6:15:2 to obtain the mixture.

[0097] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0098] Example 9 The only difference from Example 1 is that in step (2), coke powder, phenolic resin, water, and boron oxide are uniformly mixed in a mass ratio of 100:3:15:2 to obtain the mixture.

[0099] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0100] Example 10 The only difference from Example 1 is that in step (2), coke powder, phenolic resin, water, and silicon carbide are uniformly mixed in a mass ratio of 100:20:15:2 to obtain the mixture.

[0101] The negative electrode material obtained in this embodiment contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being secondary particle artificial graphite.

[0102] Example 11 The only difference from Example 1 is that in step (2), coke powder, phenolic resin, water, and sodium borate are uniformly mixed in a mass ratio of 100:6:5:2 to obtain the mixture.

[0103] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0104] Example 12 The only difference from Example 1 is that in step (2), coke powder, phenolic resin, water, and boron oxide are uniformly mixed in a mass ratio of 100:6:50:2 to obtain the mixture.

[0105] As can be seen from the scanning electron microscope image in Figure 1, the anode material obtained in this embodiment contains primary and secondary particles, the majority of which are primary particle artificial graphite, and as can be seen from the pore size distribution curve in Figure 2, the anode material contains pores, which mainly consist of micropores and mesopores.

[0106] Example 13 The only difference from Example 1 is that in step (2), coke powder, phenolic resin, water, and boron chloride are uniformly mixed in a mass ratio of 100:6:15:1 to obtain the mixture.

[0107] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0108] Example 14 The only difference from Example 1 is that in step (2), coke powder, phenolic resin, water, and boron oxide are uniformly mixed in a mass ratio of 100:6:15:5 to obtain the mixture.

[0109] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0110] Example 15 The only difference from Example 1 is that the press forming pressure in step (3) is 5 MPa.

[0111] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0112] Example 16 The only difference from Example 1 is that the press forming pressure in step (3) is 100 MPa.

[0113] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0114] Example 17 The only difference from Example 1 is that the temperature of the pre-carbonization treatment of the precursor in step (4) is 500°C.

[0115] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0116] Example 18 The only difference from Example 1 is that the temperature of the pre-carbonization treatment of the precursor in step (4) is 1200°C.

[0117] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0118] Example 19 The only difference from Example 1 is that the temperature of the graphitization treatment in step (5) is 2800°C.

[0119] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0120] Example 20 The only difference from Example 1 is that the temperature of the graphitization treatment in step (5) is 3000°C.

[0121] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0122] Example 21 The only difference from Example 1 is that the holding time for the graphitization treatment in step (5) is 2 hours.

[0123] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0124] Example 22 The only difference from Example 1 is that the holding time for the graphitization treatment in step (5) is 4 hours.

[0125] The negative electrode material obtained in this example contains primary particle artificial graphite and secondary particle artificial graphite, with the majority being primary particle artificial graphite.

[0126] Comparative Example 1 The difference from Example 1 is that the second precursor obtained in step (4) is placed in a graphite crucible, the graphite crucible is then moved into an Acheson furnace, and the negative electrode material is obtained through high-temperature graphitization. The maximum temperature during the graphitization process is 2900°C, the holding time at the maximum temperature is 2.5 hours, the heating rate during the graphitization process is 0.7°C / min, and the cooling rate is 0.1°C / min to obtain the negative electrode material.

[0127] Comparative Example 2 The raw coke raw material of Daqing Petroleum Coke is crushed and shaped using a shaping device to obtain crushed and shaped coke powder. The obtained coke powder, which has a median diameter of 15 μm, is placed directly into a graphite crucible, and the graphite crucible is then moved into an Acheson furnace to obtain the anode material through high-temperature graphitization. In the graphitization process, the maximum temperature is 2900°C, the maximum temperature is maintained for 8 hours, the heating rate is 0.7°C / min, and the cooling rate is 0.1°C / min to obtain the anode material.

[0128] Comparative Example 3 The raw coke raw material from Daqing Petroleum Coke was pre-carbonized at 800°C for 4 hours, then fed into a continuous graphitization furnace. The heating curve was raised to 2800°C at a heating rate of 15°C / min, maintained at 2800°C for 2.5 hours, and then cooled to 30°C at a cooling rate of 10°C / min. The heating and cooling rate ratio during the graphitization process was controlled to 1.5. The graphitized product was then crushed and shaped to obtain the anode material, and the median diameter of the crushed anode material was controlled to 15 μm.

[0129] Measurement method (1) The method for measuring the median diameter of the negative electrode material is: The objective is to measure the particle size distribution range of the negative electrode material using a Malvern laser particle size analyzer.

[0130] (2) The method for measuring the pore volume and average pore diameter of the negative electrode material is: The measurements were performed using an ASAP 2460 instrument manufactured by Micromerities, Inc., USA. The pore volume V and average pore diameter were calculated within the pore diameter range of 17 Å to 3000 Å using the BJH desorption cumulative volume of pores model.

[0131] (3) The method for measuring the specific surface area of ​​the negative electrode material is: The measurement was performed using the JW-DX dynamic rapid specific surface area analyzer manufactured by Beijing Jingwei Gaobo Science and Technology Co., Ltd., and the unit is m. 2 The condition is / g.

[0132] (4) The method for measuring the true density of the negative electrode material is: The true specific gravity of the material was obtained by accurately measuring its true volume using an Anton Paar Quanta PENTAPYC 5200e true density meter. This was achieved by applying the Archimedes principle of gas displacement (density = mass / volume) and utilizing the Borr law (PV=nRT) under constant conditions for an inert gas with a small molecular diameter. The unit is g / cm³. 3 That is the case.

[0133] (5) The method for measuring the surface morphology of the negative electrode material is: The surface morphology of the negative electrode material particles was observed using a Hitachi S4800 scanning electron microscope.

[0134] (6) X-ray diffraction determines the interlayer distance d of the crystal plane of the material (002) plane. 002 This represents the peak intensity of the (002) plane and the (110) plane, and the ratio of the peak intensity of the (004) plane and the (110) plane, with the unit being Å.

[0135] (7) The method for measuring battery performance is: The negative electrode materials produced in Examples 1-22 and Comparative Examples 1-3 were mixed uniformly with carboxymethylcellulose (abbreviated as CMC), conductive carbon black (abbreviated as SP), and styrene-butadiene rubber (abbreviated as SBR) in deionized water at a mass ratio of 95:1.5:1.5:2 by magnetic stirring for 8 hours. The resulting slurry was coated onto copper foil and vacuum-dried at 60°C to form the working electrode. Metallic lithium was used as the counter electrode and reference electrode, the separator was Celgard 2325, and the electrolyte was 1 mol·L-1LiPF6-EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) (volume ratio 1:1:1). The assembly of the CR2016 type coin cell was completed in a glove box filled with high-purity argon gas.

[0136] The initial discharge capacity / initial discharge efficiency was measured using a LAND battery measuring device. The charge / discharge conditions were as follows: leave for 2 hours, discharge to 0.005V at 0.1C, discharge to 0.001V at 0.09C, 0.08C...0.02C, leave for 15 minutes, charge to 1.5V at 0.1C, and leave for 15 minutes.

[0137] The button-type half-cell was subjected to rate characteristic measurements in an environment of 25±2℃ to obtain the charge-discharge ratio capacities and Coulomb efficiencies of 0.2C, 1C, and 2C.

[0138] The method for measuring cycle expansion involves manufacturing electrode pieces from the negative electrode material, assembling them into a molded battery, and recording the expansion rate of the molded battery over 20 cycles using a sensor. The expansion rate is calculated as: Expansion rate = Change in electrode piece thickness d / Original electrode piece thickness × 100%.

[0139] The results of performance measurements of the negative electrode materials obtained in the above examples and comparative examples are shown in Table 1 below, and the results of performance measurements of batteries manufactured using the negative electrode materials are shown in Table 2 below.

[0140] [Table 1]

[0141] [Table 2]

[0142] As can be seen from the measurement data of Examples 1 to 22, pores are formed inside and / or on the surface of the graphite manufactured in the embodiments of this application, improving the high-rate charging performance of the material. When the negative electrode material is applied as an electrode in a lithium-ion battery, lithium ions readily bond with carbon atoms in the artificial graphite with low resistance, rapidly diffuse into the solid-liquid interface and solid phase, reduce concentration polarization, and are advantageous for improving the rate characteristics of the negative electrode material. Herein, in Examples 3 and 4, needle coke is used as the coke raw material, so the measured rate characteristics of the batteries are inferior to those of the other embodiments. This is due to the properties of needle coke itself, and it is not considered that the technical proposal of this application cannot solve the problem of inferior rate characteristics.

[0143] Furthermore, when V×S / D is controlled within the range of 4.0 to 10, the more effective active sites on the surface of the artificial graphite that generate the reaction of releasing and intercalating lithium as a negative electrode material, the higher the specific capacity of the negative electrode material tends to be.

[0144] The negative electrode materials produced in the Acheson graphitization furnaces of Comparative Examples 1 and 2 have a certain pore structure, but the V×S / D ratio deviates from the above range, and the rate characteristics when using artificial graphite as the negative electrode material are clearly reduced. Furthermore, the production process consumes a large amount of energy, the thermal energy utilization rate is high, and the production time and cost are clearly increased.

[0145] Comparative Example 3 used a continuous graphitization process to produce the anode material. However, since coke raw material particles were directly fed into the continuous graphitization furnace, no additives were used, and no other process improvements such as controlling the heating / cooling rate ratio were made, the V×S / D ratio deviated from the above range, and the capacity and magnification performance were inferior to Example 1, which was produced under equivalent process conditions.

[0146] Although this application is disclosed by the above preferred embodiments, it is not intended to limit the scope of the claims, and any person skilled in the art may make some possible changes or modifications without departing from the technical concept of this application. Therefore, the scope of protection of this application should be limited to the scope set forth in the claims.

Claims

1. A negative electrode material containing artificial graphite, wherein the artificial graphite has pores inside and / or on its surface, and the pore volume of the negative electrode material is V cm². 3 The true density is D g / cm³ / kg. 3 The specific surface area is S m 2 When expressed as / g, 4.0 ≤ V × S / D ≤ 10, The pore volume and the average pore diameter were measured using a high-throughput specific surface area and pore distribution analyzer and calculated within the pore diameter range of 17 Å to 3000 Å using the BJH Desorption Cumulative Volume of Pores model. The average pore diameter of the aforementioned pores is 50 Å to 200 Å. When the pore volume of the negative electrode material is set to V cm³ / kg, 5 ≤ V ≤ 8. When the specific surface area of ​​the negative electrode material is set to S m² / g, 1.78 ≤ S ≤ 3.0, When the true density of the negative electrode material is set to D g / cm³, then 2.210 ≤ D ≤ 2.

265. A negative electrode material characterized in that, when measured by X-ray diffraction, the peak intensity ratio (I 002 / I 110) of the (002) plane and the (110) plane of the artificial graphite is 65.0 to 120.0, and the peak intensity ratio (I 004 / I 110) of the (004) plane and the (110) plane is 3.0 to 6.

0.

2. The negative electrode material according to claim 1, characterized in that it satisfies at least one of the following features (1) to (3). (1) Particle size D of the negative electrode material 50 The size is between 10 μm and 30 μm; (2) Particle size D of the negative electrode material 10 The size is ≥ 5 μm; (3) Particle size D of the negative electrode material 90 The size is ≤ 50 μm.

3. The negative electrode material according to claim 1 or 2, characterized in that the pores include at least one of micropores and mesopores.

4. When measured by X-ray diffraction, the interplanar spacing of the (002) plane is d 002 When this is done, 3.355 Å ≤ d 002 The negative electrode material according to claim 1 or 2, characterized in that it is ≤ 3.365 Å.

5. The negative electrode material according to claim 1 or 2, characterized in that the artificial graphite comprises artificial graphite primary particles and / or artificial graphite secondary particles.

6. The anode material according to claim 1 or 2, characterized in that it satisfies at least one of the following features (1) to (2). (1) The negative electrode material further comprises amorphous carbon; (2) The negative electrode material further contains amorphous carbon, and the mass ratio of amorphous carbon in the negative electrode material is 0.1 wt% to 5 wt%.

7. A battery characterized by comprising the negative electrode material described in claim 1 or 2.

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