Anode materials, batteries

Abstract

The present application provides a negative electrode material and a battery. [Solution] The negative electrode material includes artificial graphite, and the artificial graphite has pores inside and / or on its surface. The negative electrode material has an oil absorption of 0 mL / 100 g and a pore volume of V cm 3 / kg, specific surface area is Sm 2 / g, 400≦O×V×S≦1500. The negative electrode material provided by the present application can improve the adsorption and infiltration ability of the negative electrode material for the electrolyte without affecting the processing performance, and can improve the high-rate charge / discharge performance of the negative electrode material.

Description

[Technical Field]

[0001] This application relates to the technical field of anode materials, and more particularly to anode materials, batteries. [Background technology]

[0002] Graphite has advantages such as high electrical conductivity, a large lithium ion diffusion coefficient, a layered structure with a small volume change before and after lithium absorption, a high lithium absorption capacity, and a low lithium absorption potential, making it the mainstream negative electrode material for commercial lithium-ion batteries.

[0003] Conventional graphitization equipment for graphite anodes is mainly divided into two types: crucible furnaces and box furnaces. Both are batch-type operations, and require power outages during the graphitization process, making continuous production impossible. Furthermore, the heating and cooling processes of the equipment are limited, and the heating and cooling rates are slow, resulting in long production cycles, typically within 15 to 50 days. During the graphitization production process, volatile components and impurity elements in the raw materials are released under high-temperature conditions, forming pores inside and / or on the surface of the graphite. Generally, all artificial graphites have a certain number of pore structures, and the presence of pores is due to the presence of Li + This increases the diffusion channels inside the graphite material, + While reducing the diffusion resistance of graphite can effectively improve the rate performance of the material, excessive pore structure increases the specific surface area of ​​the material, further deteriorating the initial efficiency and cycle performance of the product. In fact, simply improving the pore structure alone cannot achieve optimal rate performance, and there is still significant room for improvement. Researchers have only studied the effect of a single factor on the performance of graphite materials, and have not delved into the synergistic effects between multiple factors to maximize the improvement of graphite's rate performance.

[0004] Therefore, at the current stage in which the development of graphite materials has reached maturity, improving a single parameter cannot meet the market demand for low-cost, high-performance graphite materials. It is necessary to study the synergistic action mechanism of various factors and develop graphite anode materials that meet market demands. Summary of the Invention [Problem to be solved by the invention]

[0005] In view of this, the present application provides a negative electrode material and a battery, which can improve the active sites and diffusion channels that release and store lithium ions in the negative electrode material, thereby improving the high-rate charge-discharge performance of the negative electrode material. [Means for solving the problem]

[0006] In a first aspect, the present application provides a negative electrode material, the negative electrode material comprising artificial graphite, the artificial graphite having a pore structure inside and / or on a surface thereof, the negative electrode material having an oil absorption of 0 mL / 100 g and a pore volume of V cm 3 / kg, and the specific surface area is Sm 2 / g, 400≦O×V×S≦1500, The pore volume was measured using an ASAP2460 apparatus (Micromeritics, USA) and calculated within the pore diameter range of 17 Å to 3000 Å using the BJH Desorption cumulative volume of pores model.

[0007] In some embodiments, the negative electrode material has an oil absorption of 0 mL / 100 g, and 43≦0≦60.

[0008] In some embodiments, the negative electrode material has a pore volume of Vcm 3 / kg, 5≦V≦8.

[0009] In some embodiments, the negative electrode material has a specific surface area of ​​Sm 2 / g, 1.78≦S≦3.0.

[0010] In some embodiments, the negative electrode material has a particle size that satisfies 0.9≦(D90−D10) / D50≦1.8 and 10 μm≦D50≦30 μm.

[0011] In some embodiments, the negative electrode material further comprises amorphous carbon.

[0012] In some embodiments, the negative electrode material further includes amorphous carbon, and the mass percentage of the amorphous carbon in the negative electrode material is 0.1 wt % to 5 wt %.

[0013] In some embodiments, the negative electrode material is measured by Raman spectroscopy, and the Raman spectrum is measured at 1300 cm -1 ~1400cm -1 Peak intensity I in the range D and 1580cm -1 ~1620cm -1 Peak intensity I in the range G Intensity ratio I D / I G is 0.03≦I D / I G ≦0.10.

[0014] In some embodiments, the negative electrode material comprises primary particles of artificial graphite and / or secondary particles of artificial graphite.

[0015] In some embodiments, the pores comprise at least one of micropores and mesopores.

[0016] In a second aspect, the present application provides a battery comprising the artificial graphite negative electrode material according to the first aspect. [Effects of the Invention]

[0017] The technical solution of the present application has at least the following beneficial effects: Those skilled in the art will recognize that the pore volume of artificial graphite within a certain range is Li +The applicant has found that a certain range of specific surface area can increase the diffusion channels of lithium ions, ensuring sufficient electrochemical reaction interfaces, promoting the diffusion of lithium ions at the solid-liquid interface and within the solid phase, reducing concentration polarization, and improving the capacity and rate performance of negative electrode materials. Based on this, the applicant has conducted extensive research and found that the desorption and absorption of lithium ions not only requires diffusion channels and reaction interfaces, but also requires an electrolyte as a medium. If some pores are not infiltrated with the electrolyte due to the influence of surface morphology or other factors, they cannot function, and the corresponding surfaces naturally cannot undergo electrochemical reactions. This corresponds to a lack of "effective electrochemical reaction space." Therefore, simply having sufficient pore volume and specific surface area does not necessarily effectively improve rate performance. The infiltration capacity of the electrolyte is generally determined by the oil absorption capacity. This application has conducted extensive experimental research into the combination of the three factors of pore volume, specific surface area, and oil absorption, and has found that by controlling the O×V×S of the anode material within the above range, there is sufficient reaction space for effective lithium ion absorption and desorption in the anode material, which is advantageous for improving the high-rate charge-discharge performance of artificial graphite anode materials.

[0018] The anode material provided by this application is manufactured and processed using a continuous graphitization process, in which materials are continuously fed and discharged, the paths and times through which all materials pass are synchronized, and the times and temperatures through which they pass through the high-temperature zone are synchronized. By controlling the heating and cooling rates during the calcination and graphitization stages during the graphitization process, volatile components, impurities, and other substances within the material can be uniformly and quickly released. At the same time, a certain amount of additives can be introduced to precisely control the pore volume within and / or on the surface of the graphite. By synergistically using the above processes, the relationship between specific surface area, oil absorption, and pore volume can be precisely controlled to satisfy 400≦O×V×S≦1500.

[0019] The negative electrode material provided by the present application has low energy consumption per unit mass, has obvious advantages in cost and production cycle, and is environmentally friendly. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a scanning electron microscope photograph of the artificial graphite negative electrode material provided in Example 12 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0021] In order to better explain the present application and facilitate understanding of the technical solution of the present application, the present application will be described in more detail below. It should be noted that the following examples are merely simplified examples of the present application and do not indicate or limit the scope of protection of the present application. The scope of protection of the present application is subject to the scope of the claims.

[0022] In the field of anode materials, development of continuous graphitization equipment has continued for decades, with patent US06619591 as early as 1987 disclosing equipment capable of continuous graphitization of carbon-containing materials. In recent years, applicants have also continued to develop continuous graphitization equipment. For example, patent CN211425033U, filed in 2019, discloses a vertical continuous kiln for producing anode materials for lithium batteries, in which material is continuously discharged from an outlet and continuously fed through a material pipe. Compared to conventional processes, continuous graphitization processes shorten the graphitization time from days to hours, significantly reducing energy consumption. However, the significant reduction in graphitization time also results in changes to the microstructure of the artificial graphite, particularly changes to the pore structure and crystalline form within the artificial graphite, compared to conventional artificial graphite. It has been proven in the industry that such changes make it difficult to meet the required performance of artificial graphite and are difficult to improve. Therefore, even though continuous graphitization equipment has been in existence for 30 to 40 years, there has been no precedent for successful mass production of continuously graphitized artificial graphite anode products.

[0023] In recent years, with the increasing energy scarcity, in order to further reduce the cost of artificial graphite, the applicant has continued to develop the application of continuous graphitization equipment to develop an artificial graphite anode material that is equivalent to or even better in performance than current conventional graphitized anode materials, with the goal of reducing the energy consumption of artificial graphite anode materials and further reducing costs. Through the development of mass production processes, the applicant has developed various means to improve the rapid temperature changes that cause adverse changes in artificial graphite products, and by product selection, has obtained a series of different types of artificial graphite anode materials. Although these artificial graphite anode materials differ from conventional artificial graphite products in microstructure, their electrical performance can all be basically equivalent to that of conventional artificial graphite products, and in some respects, their electrical performance and processing performance are superior or more stable, making them eligible to replace conventional artificial graphite products.

[0024] The manufacturing process and related products will be described in more detail below, taking as an example a manufacturing process developed by the applicant.

[0025] The method for producing the negative electrode material includes the following steps. In S10, the raw coke is calcined at a temperature of 500 to 1200°C for 3 to 6 hours, the temperature increase rate during the calcination process is 2 to 10°C / min, and low-temperature calcined coke is obtained after natural cooling. In S20, the low-temperature calcined coke is subjected to a shaping process to obtain coke powder having a median diameter of 10 μm to 20 μm. In S30, the mixture containing the coke powder, adhesive, additives and solvent is pressed at a pressure of 5 MPa to 100 MPa to obtain a precursor in which the mass ratio of the coke powder to the additives is 100:(1 to 5). In S40, the precursor is placed in a continuous graphitization furnace and heated to 2800°C to 3200°C at a heating rate of 12°C / min to 20°C / min, and then further maintained at 2800°C to 3200°C for 2 hours to 5 hours, after which it is cooled to 30°C at a heating rate of 15°C / min to 25°C / min to obtain the negative electrode material.

[0026] The method for producing a negative electrode material provided in this application involves grinding low-temperature calcined coke obtained by raw coke calcination into coke powder, using a slow heating rate during the low-temperature calcination step to gradually release volatile components and control the initial pore structure formation process, pressing the mixture of coke powder, binder, additives, and solvent, and directly placing the precursor in a continuous graphitization furnace. The heating rate is very fast, allowing the precursor to reach the graphitization temperature in a short time, allowing the additives to rapidly volatilize and escape, further forming pores within and / or on the surfaces of the graphite particles. The presence of pores contributes to improving the specific surface area and oil absorption, increasing the reactive area of ​​the electrode of the negative electrode active material, and improving the high-rate charge / discharge performance of the material. Furthermore, the process of loading and unloading the material from the continuous graphitization furnace can be completed within a few hours, resulting in high thermal energy utilization and low production costs.

[0027] In some embodiments, the green coke feedstock comprises at least one of petroleum coke, needle coke, pitch coke, and isotropic coke.

[0028] In some embodiments, the heating rate during the calcination treatment may be, for example, 2°C / min, 3°C / min, 5°C / min, 6°C / min, 8°C / min, 9°C / min, or 10°C / min. As can be seen, a heating rate during the calcination treatment within the above range is advantageous for gradually releasing volatile components in the raw materials, thereby preliminarily forming a pore structure, which, combined with the rapid heating during the subsequent graphitization process, results in a negative electrode material that satisfies 400≦O×V×S≦1500.

[0029] In some embodiments, the temperature of the calcination treatment may be, for example, 500°C, 550°C, 600°C, 700°C, 750°C, 800°C, 850°C, 900°C, 1000°C, or 1200°C, but is not limited to the listed values, and other unlisted values ​​within the ranges also apply. As can be understood, having the calcination treatment temperature within the above ranges is advantageous for removing substances such as volatile components from the raw coke raw material.

[0030] In some embodiments, the incubation time for the calcination treatment may be, for example, 3 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, or 6 hours, but is not limited to the listed values, and other values ​​not listed within the range also apply. Preferably, the incubation time for the calcination treatment is 3 hours to 4 hours.

[0031] In some embodiments, the shaping comprises at least one of milling, spheronizing, or sieving.

[0032] The median diameter of the coke powder obtained by shaping is 10 μm to 20 μm, and more specifically, may be 12 μm, 13 μm, 14 μm, 16 μm, 18 μm, 18.5 μm, 19 μm, or 20 μm, but is not limited to the listed numerical values, and other unlisted numerical values ​​within the numerical range also apply. Controlling the median diameter of the coke powder within the above range through multiple tests is advantageous in achieving both processability, capacity, and rate characteristics.

[0033] In some embodiments, the mass content of carbon in the coke powder is 80% or more, and may be, for example, 80%, 81%, 82%, 85%, 90%, 95%, or 96%, but is not limited to the recited values, and other unrecited values ​​within the range also apply.

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

[0035] In some embodiments, the adhesive comprises at least one of heavy oil, mineral oil, coal tar, pitch, petroleum resin, phenolic resin, epoxy resin, coumarone resin, potato starch, wheat starch, corn starch, sweet potato starch, arrowroot starch, and tapioca flour. The pitch may comprise at least one of petroleum-based liquid pitch and coal-based liquid pitch. Specifically, the petroleum-based liquid pitch may be petroleum pitch, modified pitch, mesophase pitch, etc.

[0036] In some embodiments, the additive comprises at least one of boron oxide, boron carbide, boron nitride, silicon carbide, boron carbide, boron nitride, boric acid, boron chloride, and sodium borate, and the additive acts as a graphitization catalyst while being volatilized and released by rapid temperature increase and decrease 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, adhesive, solvent, and additive 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 recited values, and other unrecited values ​​within the range also apply. Controlling the content of the additive within the above range is advantageous for catalyzing the graphitization process while also forming a certain number of pores within the graphite.

[0038] 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, a propeller stirrer, a turbine stirrer, a flat blade stirrer, or the like can be used as long as the components in the mixture are sufficiently mixed uniformly.

[0039] In some embodiments, the stirring speed is 10 r / min to 1000 r / min, and specifically, may 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 the components to form a uniform mixture.

[0040] The stirring may be carried out at room temperature or in a preheated state, 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 uniform mixture.

[0041] In some embodiments, the pressing method includes at least one of extrusion, die pressing, roll pressing, and isostatic pressing.

[0042] In some embodiments, the pressing pressure may be, for example, 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, and the pressing process can improve the fluidity of the material during the graphitization process while increasing the furnace loading and production capacity of the material.

[0043] In some embodiments, the temperature for graphitization may be, for example, 2800°C, 2900°C, 3000°C, 3100°C, 3150°C, 3180°C, or 3200°C, but is not limited to the listed values, and other unlisted values ​​within the ranges also apply.

[0044] In some embodiments, the graphitization treatment incubation time may be, for example, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 3.8 hours, 4 hours, 4.5 hours, or 5 hours, but is not limited to the listed values, and other unlisted values ​​within the range also apply. Preferably, the graphitization treatment incubation time is 2 hours to 3 hours.

[0045] In some embodiments, the heating rate of the graphitization treatment may be, but is not limited to, 12°C / min, 13°C / min, 14°C / min, 16°C / min, 18°C / min, 18.5°C / min, or 20°C / min. Rapid heating is advantageous for forming pores in and / or on the surface of the graphite material and for controlling the specific surface area.

[0046] In some embodiments, the cooling rate after graphitization is 15°C / min to 25°C / min, and specifically may be 15°C / min, 16°C / min, 17°C / min, 18°C / min, 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 listed values, and other unlisted values ​​within the range also apply. Rapid cooling is advantageous for controlling the specific surface area and oil absorption of the material, and can significantly shorten the graphitization processing cycle and reduce production costs.

[0047] In some embodiments, the graphitization treatment is followed by at least one of pulverization, sieving, and demagnetization. Preferably, the carbonization treatment is followed by pulverization, demagnetization, and sieving, in that order.

[0048] In some embodiments, the grinding means may be any one of a mechanical grinder, an airflow grinder, and a cryogenic grinder.

[0049] In some embodiments, the sieving method is any one of a fixed sieve, a drum screen, a resonating sieve, a roller sieve, a vibrating sieve, and a chain grizzly sieve, and the mesh number of the sieve is 100 to 500 mesh. Specifically, the mesh number of the sieve may be 100 mesh, 200 mesh, 250 mesh, 325 mesh, 400 mesh, 500 mesh, etc., and controlling the particle size of the negative electrode material within the above range contributes to improving the processing characteristics of the negative electrode material.

[0050] In some embodiments, the demagnetizing device is any one of a permanent magnet drum magnetic separator, an electromagnetic iron remover, and a pulsating high gradient magnetic separator, and the demagnetization is ultimately for controlling the content of magnetic materials in the negative electrode material, for avoiding the discharging effect of the magnetic materials on the lithium ion battery, and for ensuring the safety of the battery during use.

[0051] A negative electrode material containing artificial graphite, the artificial graphite having pores inside and / or on the surface, and an oil absorption of 0 mL / 100 g and a pore volume of V cm 3 / kg, and the specific surface area is Sm 2 / g, the pore volume is 400≦O×V×S≦1500, and the pore volume is measured using an ASAP 2460 device manufactured by Micromeritics, USA, and calculated using the BJH Desorption cumulative volume of pores model within the pore diameter range of 17 Å to 3000 Å.

[0052] The anode material provided by the present application is produced and processed by a continuous graphitization process, in which the material is first calcined by rapidly heating at a low temperature, and then graphitized by rapidly heating at a high temperature. At the same time, a certain amount of additives is added to the raw material to precisely control the pores inside and / or on the surface of the graphite, so that the pore volume, specific surface area, and oil absorption of the material meet the ideal adjustment and control design requirements.

[0053] Those skilled in the art will recognize that the pore volume of artificial graphite within a certain range is Li +The applicant has found that a certain range of specific surface area can increase the diffusion channels of lithium ions, ensuring sufficient electrochemical reaction interfaces, promoting the diffusion of lithium ions at the solid-liquid interface and within the solid phase, reducing concentration polarization, and improving the capacity and rate performance of negative electrode materials. Based on this, the applicant has conducted extensive research and found that the desorption and absorption of lithium ions not only requires diffusion channels and reaction interfaces, but also requires an electrolyte as a medium. If some pores are not infiltrated with the electrolyte due to the influence of surface morphology or other factors, they cannot function, and the corresponding surfaces naturally cannot undergo electrochemical reactions. This corresponds to a lack of "effective electrochemical reaction space." Therefore, simply having sufficient pore volume and specific surface area does not necessarily effectively improve rate performance. The infiltration capacity of the electrolyte is generally determined by the oil absorption capacity. This application has conducted extensive experimental research into the combination of the three factors of pore volume, specific surface area, and oil absorption, and has found that by controlling the O×V×S of the anode material within the above range, there is sufficient reaction space for effective lithium ion absorption and desorption in the anode material, which is advantageous for improving the high-rate charge-discharge performance of artificial graphite anode materials.

[0054] In some embodiments, when the oil absorption of the negative electrode material is 0 mL / 100 g, the range is 43≦0≦60, and specifically, the range may be, but is not limited to, 43, 44, 45, 47, 49, 51, 52, 53, 54, 55, 57, 59, or 60. Controlling the oil absorption of the material within the above range is advantageous for improving the adsorption and infiltration performance of the material with respect to the electrolyte, and improves the electrochemical performance of the negative electrode material.

[0055] In some embodiments, the pore volume of the negative electrode material is Vcm 3 / kg, V satisfies 5≦V≦8, and specifically may be 5.1, 5.2, 5.5, 5.8, 6.0, 6.2, 6.5, 6.8, 7.0, 7.2, 7.5, or 8.0, but is not limited thereto. When the pores cause an electrochemical reaction inside the electrode, the pores create more lithium ion diffusion channels and electrochemical reaction interfaces in the negative electrode material, promoting the diffusion of lithium ions at the solid-liquid interface and within the solid phase, reducing concentration polarization, and favoring the improvement of the rate performance of the negative electrode material.

[0056] In some embodiments, the specific surface area of ​​the negative electrode material is determined by Sm 2 / g, 1.78≦S≦3.0, and specifically, it may be 1.79, 1.85, 1.95, 2.00, 2.25, 2.43, 2.57, 2.61, 2.72, 2.85, 2.90, 3.0, etc., but is not limited thereto. As can be understood, if the specific surface area is too large, it is likely to cause the formation of a solid electrolyte membrane, which will result in excessive consumption of irreversible lithium salt and reduce the initial efficiency of the battery.

[0057] In some embodiments, the pores comprise at least one of micropores and mesopores.

[0058] In some embodiments, the particle size D of the negative electrode material 50 Specifically, the thickness may be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 20 μm, 25 μm, 30 μm, or the like, and is not limited thereto.

[0059] In some embodiments, the particle size of the negative electrode material is 0.9≦(D 90 -D 10 ) / D 50 ≦1.8, and specifically, it may be 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, etc., but is not limited thereto. When the particle size of the negative electrode material satisfies the above relationship, a concentrated particle size distribution and an appropriate deposition density of the negative electrode material can be ensured.

[0060] The particle size distribution was measured using a laser diffraction method. body In the cumulative particle size distribution based on the volume, D 10 represents the particle size corresponding to the percentage of the cumulative particle size distribution of the powder reaching 10%, and D 50 represents the particle size corresponding to the cumulative particle size distribution percentage reaching 50%, and D 90 represents the particle size corresponding to when the cumulative particle size distribution percentage reaches 90%.

[0061] In some embodiments, the negative electrode material further comprises amorphous carbon.

[0062] In some embodiments, the negative electrode material further comprises amorphous carbon, and the mass proportion of the amorphous carbon in the negative electrode material is 0.1 wt % to 5 wt %, and the mass proportion of the amorphous carbon in the negative electrode material may be specifically 0.1 wt %, 0.3 wt %, 0.5 wt %, 1 wt %, 2 wt %, 3 wt %, 4 wt %, or 5 wt %, and the presence of amorphous carbon provides more irregular and more open diffusion paths for lithium ions, which is advantageous for improving the rate performance of the material.

[0063] In some embodiments, the negative electrode material is measured by Raman spectroscopy, and the Raman spectrum is measured at 1300 cm -1 ~1400cm -1 Peak intensity I in the range D and 1580cm -1 ~1620cm -1 Peak intensity I in the range G Intensity ratio I D / I G is 0.03≦I D / I G ≦0.10, and specifically, it may be 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, or 0.1, etc., but is not limited thereto. D / I G By controlling the amount of carbon black within the above range, the degree of graphitization of the negative electrode material can be improved, resulting in better quality graphite crystals.

[0064] In some embodiments, the negative electrode material comprises primary synthetic graphite particles and / or secondary synthetic graphite particles.

[0065] In some embodiments, the pores comprise at least one of micropores and mesopores.

[0066] In some embodiments, the specific capacity of the negative electrode material is 320 mAh / g to 370 mAh / g, and specifically may 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, etc., but is not limited thereto.

[0067] A battery comprising the above negative electrode material.

[0068] As will be apparent to those skilled in the art, the battery manufacturing method described above is merely an example, and other methods commonly used in the art may be employed without departing from the scope of the present disclosure, and other types of batteries, such as sodium ion batteries and potassium ion batteries, may be manufactured and measured. [Example]

[0069] The present application will be further described below with reference to several examples. However, the present application is not limited to the following specific examples. Appropriate modifications can be made within the scope of protection.

[0070] Example 1 The method for manufacturing the composite negative electrode material of this example includes the following steps. (1) Daqing petroleum coke was calcined at 800℃ for 4 hours, and the temperature increase rate during the calcination process was 5℃ / min. After cooling, low-temperature calcined coke was obtained. (2) The low-temperature calcined 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. (3) Coke powder, coal tar, quinoline, and silicon carbide were uniformly mixed in a mass ratio of 100:5:15:2 to obtain a mixture. (4) The mixture was pressed at a pressure of 20 MPa to obtain a precursor. (5) The precursor was graphitized in a continuous graphitization furnace at 3000°C to obtain a graphitized product. The temperature rise curve was as follows: the temperature was raised to 3000°C at a rate of 16.5°C / min, the temperature was maintained at 3000°C for 3 hours, and then the temperature was lowered to 30°C at a rate of 16.0°C / min. (6) The graphitized product was subjected to processes such as dispersion, demagnetization, and sieving through a 250 mesh to obtain artificial graphite negative electrode material.

[0071] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0072] Example 2 The method for manufacturing the composite negative electrode material of this example includes the following steps. (1) Baosteel pitch coke was calcined at 750℃ for 4 hours, and the temperature increase rate during the calcination process was 3℃ / min. After cooling, low-temperature calcined coke was obtained. (2) The low-temperature calcined 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. (3) Mixture A was obtained by uniformly mixing coke powder, starch, water, and sodium borate in a mass ratio of 100:6:20:2. (4) The mixture was pressed at a pressure of 20 MPa to obtain a precursor. (5) The precursor was graphitized in a continuous graphitization furnace at 2950°C to obtain a graphitized product. The temperature rise curve was as follows: the temperature was raised to 2950°C at a rate of 15°C / min, kept at 2950°C for 3 hours, and then cooled to 30°C at a rate of 20°C / min. (6) The graphitized product was subjected to processes such as dispersion, demagnetization, and sieving through a 250 mesh to obtain artificial graphite negative electrode material.

[0073] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0074] Example 3 The method for manufacturing the composite negative electrode material of this example includes the following steps. (1) Daqing petroleum coke was calcined at 800℃ for 4 hours, and the temperature increase rate during the calcination process was 6℃ / min. After cooling, low-temperature calcined coke was obtained. (2) The low-temperature calcined 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. (3) Mixture A was obtained by uniformly mixing coke powder, coal tar, quinoline, and boron nitride in a mass ratio of 100:5:15:3. (4) The mixture was pressed at a pressure of 20 MPa to obtain a precursor. (5) The precursor was graphitized in a continuous graphitization furnace at 2900°C to obtain a graphitized product. The temperature was increased to 2900°C at a rate of 18°C / min, held at 2900°C for 3 hours, and then cooled to 30°C at a rate of 21.5°C / min. (6) The graphitized product was subjected to processes such as dispersion, demagnetization, and sieving through a 250 mesh to obtain artificial graphite negative electrode material.

[0075] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0076] Example 4 The method for manufacturing the composite negative electrode material of this example includes the following steps. (1) Daqing petroleum coke was calcined at 800℃ for 4 hours, and the temperature increase rate during the calcination process was 5℃ / min. After cooling, low-temperature calcined coke was obtained. (2) The low-temperature calcined 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. (3) Mixture A was obtained by uniformly mixing coke powder, starch, water, and boron carbide in a mass ratio of 100:6:20:2. (4) The mixture was pressed at a pressure of 20 MPa to obtain a precursor. (5) The precursor was graphitized in a continuous graphitization furnace at 3000°C to obtain a graphitized product. The temperature rise curve was as follows: the temperature was raised to 3000°C at a rate of 20°C / min, kept at 3000°C for 3 hours, and then cooled to 30°C at a rate of 16.6°C / min. (6) The graphitized product was subjected to processes such as dispersion, demagnetization, and sieving through a 250 mesh to obtain artificial graphite negative electrode material.

[0077] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0078] Example 5 The difference from Example 1 is that the calcination temperature in step (1) is 500°C.

[0079] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0080] Example 6 The difference from Example 1 is that the calcination temperature in step (1) is 1200°C.

[0081] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0082] Example 7 The difference from Example 1 is that the calcination time in step (1) is 3 hours.

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

[0084] Example 8 The difference from Example 1 is that the calcination time in step (1) is 6 hours.

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

[0086] Example 9 The difference from Example 1 is that in step (3), coke powder, coal tar, quinoline, and silicon carbide were uniformly mixed in a mass ratio of 100:3:15:2 to obtain a mixture.

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

[0088] Example 10 The difference from Example 1 is that in step (3), coke powder, coal tar, quinoline, and silicon carbide were uniformly mixed in a mass ratio of 100:20:15:2 to obtain a mixture.

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

[0090] Example 11 The difference from Example 1 is that in step (3), coke powder, coal tar, quinoline, and silicon carbide were uniformly mixed in a mass ratio of 100:5:5:2 to obtain a mixture.

[0091] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0092] Example 12 The difference from Example 1 is that in step (3), coke powder, coal tar, quinoline, and silicon carbide were uniformly mixed in a mass ratio of 100:5:50:2 to obtain a mixture.

[0093] An electron microscope photograph of the above-mentioned negative electrode material is shown in FIG. 1. As can be seen from FIG. 1, the negative electrode material is composed of primary particles and secondary particles.

[0094] Example 13 The difference from Example 1 is that in step (3), coke powder, coal tar, quinoline, and silicon carbide were uniformly mixed in a mass ratio of 100:5:15:1 to obtain a mixture.

[0095] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0096] Example 14 The difference from Example 1 is that in step (3), coke powder, coal tar, quinoline, and silicon carbide were uniformly mixed in a mass ratio of 100:5:15:5 to obtain a mixture.

[0097] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0098] Example 15 The difference from Example 1 is that the pressing pressure in step (4) is 5 MPa.

[0099] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0100] Example 16 The difference from Example 1 is that the pressing pressure in step (4) is 100 MPa.

[0101] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0102] Example 17 The difference from Example 1 is that the graphitization temperature in step (5) is 2800°C.

[0103] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0104] Example 18 The difference from Example 1 is that the graphitization temperature in step (5) is 3200°C.

[0105] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0106] Example 19 The difference from Example 1 is that the temperature retention time for the graphitization treatment in step (5) is 2 hours.

[0107] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0108] Example 20 The difference from Example 1 is that the temperature retention time for the graphitization treatment in step (5) is 5 hours.

[0109] The negative electrode material includes primary particle artificial graphite and secondary particle artificial graphite, the majority of which is primary particle artificial graphite.

[0110] Comparative Example 1 The difference from Example 1 is that the precursor obtained in step (4) is placed in a graphite crucible, and then the graphite crucible is transferred to an Acheson furnace to undergo a high-temperature graphitization process to obtain a negative electrode material. The graphitization process has a maximum temperature of 2900°C, a holding time at the maximum temperature of 3 hours, and a temperature increase rate of 0.6°C / min and a temperature decrease rate of 0.1°C / min.

[0111] Comparative Example 2 Daqing petroleum coke is crushed and shaped in a shaping device to obtain crushed and shaped coke powder. The obtained coke powder with a median diameter of 15 μm is directly placed in a graphite crucible, and the graphite crucible is then transferred to an Acheson furnace for high-temperature graphitization to obtain a negative electrode material. The graphitization process has a maximum temperature of 2900°C, a maximum temperature holding time of 8 hours, and a heating rate of 0.7°C / min and a cooling rate of 0.1°C / min.

[0112] Comparative Example 3 Daqing petroleum coke was calcined at 800°C for 4 hours at a heating rate of 1.5°C / min, then placed in a continuous graphitization furnace. The temperature was increased to 2900°C at a heating rate of 8°C / min, held at 2900°C for 3 hours, and then cooled to 30°C at a cooling rate of 10°C / min. The resulting material was crushed and shaped to a median diameter of 15μm to obtain anode material.

[0113] Measurement method (1) Measurement method for particle size of negative electrode material: The particle size distribution range of the composite negative electrode material was measured by a Malvern laser granulometer.

[0114] (2) Pore volume measurement method for negative electrode material: Measurements were performed using an ASAP 2460 device manufactured by Micromeritics, Inc., USA, and the pore volume V was calculated using the BJH Desorption cumulative volume of pores model within the pore diameter range of 17 Å to 3000 Å.

[0115] (3) Measurement method for the specific surface area of ​​the negative electrode material: Measurement was performed using a dynamic specific surface area analyzer JW-DX (manufactured by Beijing Jingwei Gaobo Science and Technology Co., Ltd.), and the unit is m 2 / g.

[0116] (4) Measurement method for the surface morphology of the negative electrode material: The surface morphology of the negative electrode material particles was observed using a S4800 scanning electron microscope (Hitachi).

[0117] (5) Method for measuring oil absorption of negative electrode material: The oil absorption was measured using an ASAHI S-500 oil absorption measuring device (manufactured by ASAHISOUKEN, Japan). The oil absorption O is the amount of linseed oil dropped when the torque due to the change in viscosity characteristics reaches 70% of the maximum torque, and is expressed in mL / 100 g.

[0118] (6) Anode Material I D / I G Measurement method: Raman spectroscopy revealed that the composite anode material exhibited a peak at 1300 cm -1 ~1400cm -1 Peak intensity I in the range D And, 1580cm -1 ~1620cm -1 Peak intensity I in the range G Relative to I D / I G was measured.

[0119] (7) Battery performance measurement method: The negative electrode materials prepared in Examples 1 to 22 and Comparative Examples 1 to 3, carboxymethyl cellulose, conductive carbon black, and styrene-butadiene rubber, were mixed uniformly in deionized water at a mass ratio of 95:1.5:1.5:2 under magnetic stirring for 8 hours. The resulting slurry was applied to copper foil and vacuum dried at 60°C to form a 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 LiPF6-EC (ethylene carbonate) / DMC (dimethyl carbonate) / EMC (ethyl methyl carbonate) (volume ratio 1:1:1). A CR2016 coin battery pack was assembled in a glove box filled with high-purity argon gas.

[0120] The initial discharge capacity / initial discharge efficiency measurements were performed using a LAND battery measuring device. The charge / discharge conditions were as follows: let stand for 2 hours, discharge at 0.1C to 0.005V, then discharge at 0.09C, 0.08C...0.02C to 0.001V, let stand for 15 minutes, charge at 0.1C to 1.5V, and let stand for 15 minutes.

[0121] The rate characteristics of the button half-cell were measured in an environment of 25±2°C, and the charge / discharge specific capacity and coulombic efficiency at 0.2C, 1C, and 2C were obtained. The charge-discharge conditions for rate measurement of the button cell were: (1) discharge at 0.1C to 0.01V, constant voltage for 5 hours, and charge at 0.1C to 1.5V; (2) discharge at 0.2C to 0.01V, constant voltage to 0.01C, and charge at 0.2C to 1.5V; (3) discharge at 0.2C to 0.01V, constant voltage to 0.01C, and charge at 2C to 1.5V; (4) discharge at 0.2C to 0.01V, constant voltage to 0.01C, and charge at 0.2C to 1.5V; (5) discharge at 1C to 0.01V, constant voltage to 0.01C, and charge at 0.2C to 1.5V; (6) discharge at 2C to 0.01V.

[0122] Whole-cell measurement: The negative electrode material obtained in each example was used as the negative electrode active material. The negative electrode active material, conductive agent, adhesive, and dispersant were dissolved and mixed in deionized water in a mass percentage of 95.2:1.5:2:1.3 to adjust the solid content to 50 wt%. The mixture was applied to an 8 μm-thick copper foil current collector and vacuum dried to produce negative electrode pieces. Lithium iron phosphate, polyvinylidene fluoride, and conductive agent carbon black were uniformly mixed with NMP (N-methylpyrrolidone) in a mass ratio of 95:2:3, then applied to a 16 μm-thick aluminum foil and vacuum dried to produce positive electrode pieces. The coated positive and negative electrode pieces were then sheet-pressed, wound, dried, filled, sealed, chemically synthesized, and capacity-graded to produce 554065-type soft-pack lithium-ion batteries.

[0123] The obtained soft-pack battery was subjected to charge / discharge measurements using a LAND battery test system (manufactured by Wuhan Jinnuo Electronics Co., Ltd.). The battery was charged / discharged at room temperature with a current of 1C / 1C, and the charge / discharge voltage was limited to 3.0V to 4.35V. The initial efficiency and 500-cycle capacity retention rate were measured (the press density of the negative electrode piece was 1.60g / cm). 3 (It is). The results of performance measurement of the negative electrode materials obtained in the above examples are shown in Table 1 below, and the results of performance measurement of the batteries manufactured using the negative electrode materials are shown in Table 2 below.

[0124] [Table 1]

[0125] [Table 2]

[0126] As can be seen from the measurement data of Examples 1 to 20, pores were formed inside and / or on the surface of the graphite prepared in the examples of the present application, and the high-rate charge / discharge performance of the material was significantly improved. This is because, when the negative electrode material is prepared as an electrode and applied to a lithium-ion battery, there is sufficient available electrochemical reaction space inside the material after the electrolyte is injected, which is advantageous for improving the rate characteristics of the negative electrode material.

[0127] The negative electrode material produced in Comparative Example 1 had an oil absorption O that was too large, so O×V×S deviated from the above range, and the rate and cycle performance of the material were both poor.

[0128] The negative electrode material prepared in Comparative Example 2 had insufficient pores in the artificial graphite, a too small pore volume V, and an O×V×S ratio outside the above range, resulting in insufficient diffusion channels for lithium ions, which was not beneficial for improving the rate characteristics of the negative electrode material.

[0129] The negative electrode material produced in Comparative Example 3 had a temperature rise rate in the calcination treatment and graphitization treatment during the production process that was outside the optimized range of the production method of the present application, and therefore O×V×S was outside the above range, resulting in a capacity and rate characteristic that was inferior to those of Example 1, which was produced under equivalent process conditions.

[0130] Although the present application has been disclosed above by way of preferred embodiments, it does not 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 idea of ​​the present application, so the scope of protection of the present application should conform to the scope defined in the claims of the present application.

Claims

1. A negative electrode material for a lithium ion battery containing artificial graphite, The artificial graphite has pores inside and / or on the surface, The negative electrode material has an oil absorption of 0 mL / 100 g and a pore volume of V cm 3 / kg, and the specific surface area is Sm 2 / g, 400≦O×V×S≦1204.5, The pore volume is measured using an ASAP 2460 device manufactured by Micromeritics Corporation of the United States, and calculated using the BJH Desorption cumulative volume of pores model within a pore diameter range of 17 Å to 3000 Å.

2. A negative electrode material for a lithium ion battery as described in claim 1, wherein the oil absorption of OmL / 100g satisfies 43≦O≦60.

3. The pore volume V cm 3 2. The negative electrode material for a lithium ion battery according to claim 1, wherein V / kg satisfies 5≦V≦8.

4. The specific surface area Sm 2 2. The negative electrode material for a lithium ion battery according to claim 1, wherein / g satisfies 1.78≦S≦3.

0.

5. The negative electrode material for a lithium ion battery according to claim 1, characterized in that the particle size satisfies 0.9≦(D90−D10) / D50≦1.8 and 10 μm≦D50≦30 μm in the volume-based cumulative particle size distribution measured using a laser diffraction method to obtain the particle size distribution.

6. The negative electrode material for a lithium ion battery according to any one of claims 1 to 5, characterized in that it satisfies at least one of the following characteristics (1) to (2): (1) The negative electrode material further includes amorphous carbon; (2) The negative electrode material further contains amorphous carbon, and the mass ratio of the amorphous carbon in the negative electrode material is 0.1 wt % to 5 wt %.

7. The negative electrode material was measured by Raman spectroscopy, and -1 ~1400cm -1 Peak intensity (I D ) and 1580 cm -1 ~1620cm -1 Peak intensity (I G ) and the intensity ratio (I D / I G ) is 0.03≦I D / I G 6. The negative electrode material for a lithium ion battery according to claim 1, wherein the ρ is ≦0.

10.

8. The negative electrode material for a lithium ion battery according to any one of claims 1 to 5, characterized in that it contains primary particles of artificial graphite and / or secondary particles of artificial graphite.

9. 6. The negative electrode material for a lithium ion battery according to claim 1, wherein the pores include at least one of micropores and mesopores.

10. A lithium ion battery comprising the negative electrode material for lithium ion batteries according to any one of claims 1 to 5.

Images