Porous carbon material, preparation method thereof, negative electrode material and secondary battery

Abstract

The application provides a kind of porous carbon material and its preparation method, negative electrode material and secondary battery, the porous carbon is granular, and the porous carbon material includes the secondary particle structure bonded by several amorphous carbon particles.The porous carbon material provided by the application has high strength and abundant microporous and mesoporous structure, which not only effectively alleviates the loss of initial efficiency and capacity of negative electrode material caused by the rupture of porous carbon particles due to the impact of stamping during the preparation of electrode, but also improves the transmission efficiency of lithium ions, stores lithium ions while avoiding excessive side reactions, so that the initial efficiency, capacity and rate performance of the negative electrode material are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of battery technology and relates to a porous carbon material and its preparation method, a negative electrode material, and a secondary battery. Background Technology

[0002] Porous materials are materials with a network structure consisting of interconnected or closed pores. They have strong adsorption properties and have been widely used in fields such as gas purification, gas separation, and wastewater treatment. They are also widely used in industrial production and people's daily lives.

[0003] In related technologies, KOH is used to activate soft carbon into porous carbon materials for application in lithium-ion batteries. However, the performance of lithium-ion batteries is limited by the pore structure and particle strength of these porous carbon materials. Furthermore, the high cost of preparing these porous carbon materials significantly restricts their large-scale application in lithium-ion batteries. Summary of the Invention

[0004] The purpose of this invention is to provide a porous carbon material and its preparation method, a negative electrode material, and a secondary battery. The porous carbon provided by this invention is composed of secondary particles formed by bonding several amorphous carbon particles, and has high strength and abundant micropores and mesopores. It can not only effectively alleviate the loss of the first-stage efficiency and capacity of the negative electrode material caused by the breakage of porous carbon particles due to stamping during the electrode preparation process, but also improve the lithium-ion transport efficiency. While realizing lithium-ion storage, it avoids the generation of too many side reactions, thereby effectively improving the first-stage efficiency and capacity of the porous carbon negative electrode material.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] In a first aspect, this application provides a porous carbon material, wherein the porous carbon is in the form of particles, and the porous carbon material includes a secondary particle structure formed by bonding a plurality of amorphous carbon particles; the mesoporous rate of the porous carbon material is 10%-40%, the microporous rate is 60%-90%, and the compressive strength of the porous carbon material is 20mN-40mN.

[0007] Preferably, the porous carbon material has a mesoporous rate of 20%-30% and a microporous rate of 70%-80%.

[0008] Preferably, the compressive strength of the porous carbon is 30mN-40mN;

[0009] Preferably, the specific surface area of ​​the porous carbon material is 1800 m². 2 / g-2200m 2 / g.

[0010] Preferably, the total pore volume of the porous carbon material is 0.8 cm³.3 / g-1.2cm 3 / g.

[0011] Preferably, the particle size D of the porous carbon material is... V 50 represents 5μm-20μm.

[0012] Secondly, the present invention provides a method for preparing porous carbon materials, the method comprising the following steps:

[0013] (1) After mixing the carbon particle precursor with the binder, the carbon particles are granulated and carbonized sequentially to obtain a porous carbon precursor.

[0014] (2) The porous carbon precursor and the solid activator are mixed and then co-activated by activator steam to obtain the porous carbon material.

[0015] Preferably, the mass ratio of the carbon particle precursor to the binder in step (1) is 1:(0.05-0.5).

[0016] Preferably, the mass ratio of the carbon particle precursor to the binder in step (1) is 1:(0.1-0.3).

[0017] Preferably, the particle size D of the carbon particle precursor in step (1) is... V 50 is 2μm-5μm.

[0018] Preferably, the adhesive in step (1) comprises any one or a combination of at least two of asphalt, tar, phenolic resin, epoxy resin or furan resin.

[0019] Preferably, the carbon particle precursor in step (1) is a soft carbon particle precursor.

[0020] Preferably, the soft carbon particle precursor includes any one or a combination of at least two of petroleum coke, pitch coke, or coal coke.

[0021] Preferably, the mass ratio of the porous carbon precursor to the solid activator in step (2) is (0.8-1.8):2.

[0022] Preferably, the mass ratio of the porous carbon precursor to the solid activator in step (2) is (1-1.5):2.

[0023] Preferably, the flow rate of the activator vapor in step (2) is 0.1 mL / g / s to 0.22 mL / g / s.

[0024] Preferably, the flow rate of the activator vapor in step (2) is 0.14 mL / g / s to 0.18 mL / g / s.

[0025] Preferably, the temperature of the co-activation treatment in step (2) is 800℃-900℃ and the time is 3h-4h.

[0026] Preferably, the heating rate of the co-activation treatment in step (2) is 3℃ / min-5℃ / min.

[0027] Preferably, the co-activation treatment in step (2) is carried out in a protective gas.

[0028] Preferably, the granulation method in step (1) includes kneading.

[0029] Preferably, the granulation temperature in step (1) is 30℃-50℃ and the time is 4h-6h.

[0030] Preferably, the carbonization temperature in step (1) is 800℃-900℃ and the time is 2h-3h.

[0031] Thirdly, the present invention provides a negative electrode material, which is obtained by carbon coating of a porous carbon material as described in the first aspect and a porous carbon material prepared by the preparation method described in the second aspect.

[0032] Fourthly, the present invention provides a secondary battery comprising the negative electrode material as described in the third aspect.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] The porous carbon provided by this invention comprises secondary particles formed by bonding several amorphous carbon particles, and has high strength and abundant micropores and mesopores. It can not only effectively alleviate the loss of first-efficiency and capacity of the negative electrode material caused by the breakage of porous carbon particles due to stamping during the electrode preparation process, but also improve the lithium-ion transport efficiency. While realizing lithium-ion storage, it avoids the generation of too many side reactions, so that the first-efficiency, capacity and rate performance of the porous carbon negative electrode material are effectively improved. Attached Figure Description

[0035] Figure 1 This is a SEM image of the porous carbon material described in Example 1 of the present invention;

[0036] Figure 2 This is a pore size distribution diagram of the porous carbon material described in Embodiment 1 of the present invention; Detailed Implementation

[0037] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention.

[0038] In a first specific embodiment, the present invention provides a porous carbon material, wherein the porous carbon is in the form of particles and has a secondary particle structure formed by bonding a plurality of amorphous carbon particles; the mesoporous rate of the porous carbon material is 10%-40%, the microporous rate is 60%-90%, and the compressive strength of the porous carbon material is 20mN-40mN.

[0039] For example, the mesoporous content of the porous carbon material can be 10%, 12%, 14%, 16%, 18%, 20%, 22%, 24%, 26%, 28%, 30%, 32%, 34%, 36%, 38%, or 40%, etc.; the microporosity can be 60%, 62%, 64%, 66%, 68%, 70%, 72%, 74%, 76%, 78%, 80%, 82%, 84%, 86%, 88%, or 90%, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0040] For example, the compressive strength of the porous carbon material can be 20mN, 25mN, 30mN, 35mN or 40mN, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] It should be noted that the definitions of micropores and mesopores in this invention are determined according to the standards of the International Union of Pure and Applied Chemistry (IUPAC).

[0042] It should be noted that the crush strength of the present invention is defined as the deformation or rupture that occurs when a material is subjected to pressure exceeding its bearing capacity under certain conditions.

[0043] The porous carbon provided by this invention is composed of secondary particles formed by bonding several soft carbon particles. It has high strength and abundant micropores and mesopores. It can not only effectively alleviate the loss of the first efficiency and capacity of the negative electrode material caused by the breakage of porous carbon particles due to stamping during the electrode preparation process, but also improve the lithium-ion transport efficiency. While realizing lithium-ion storage, it avoids the generation of too many side reactions, so that the first efficiency, capacity and rate performance of the porous carbon negative electrode material are effectively improved.

[0044] In some embodiments, the porous carbon has a mesoporous rate of 20%-30% and a microporous rate of 70%-80%.

[0045] In some embodiments, the compressive strength of the porous carbon is 30 mN-40 mN.

[0046] In some embodiments, the specific surface area of ​​the porous carbon material is 1800 m². 2 / g-2200m 2 / g.

[0047] In some embodiments, the total pore volume of the porous carbon material is 0.8 cm³. 3 / g-1.2cm 3 / g.

[0048] In some embodiments, the particle size D of the porous carbon material V 50 represents 5μm-20μm.

[0049] For example, the particle size D of the porous carbon material V 50 can be 5μm, 6μm, 7μm, 8μm, 9μm, 10μm, 11μm, 12μm, 13μm, 14μm, 15μm, 16μm, 17μm, 18μm, 19μm or 20μm, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] For example, the specific surface area of ​​the porous carbon material can be 1800 m². 2 / g、1900m 2 / g、2000m 2 / g、2100m 2 / g or 2200m 2 / g, etc., but not limited to the listed values; other unlisted values ​​within this range also apply.

[0051] For example, the total pore volume of the porous carbon material can be 0.8 cm³. 3 / g, 0.9cm 3 / g, 1.0cm 3 / g, 1.1cm 3 / g or 1.2cm 3 / g, etc., but not limited to the listed values, other unlisted values ​​within the range also apply.

[0052] It should be noted that the total pore volume of the porous carbon material described in this invention refers to the total volume of pores per unit mass of porous carbon material.

[0053] In a second embodiment, the present invention provides a method for preparing a porous carbon material, the method comprising the following steps:

[0054] (1) After mixing the carbon particle precursor with the binder, the mixture is granulated and carbonized in sequence to obtain a porous carbon precursor.

[0055] (2) The porous carbon precursor and the solid activator are mixed and then co-activated by activator steam to obtain the porous carbon material.

[0056] This invention involves mixing a carbon particle precursor with a binder, followed by granulation and carbonization to prepare a porous carbon precursor with good compressive strength. Furthermore, a co-activation method is employed to create pores in the porous carbon precursor, fully leveraging the synergistic effect of the solid-phase activator and activator vapor. This results in a porous carbon material with abundant micropores and mesopores, as well as high compressive strength. When applied to lithium-ion batteries, this effectively improves the capacity, initial efficiency, and rate performance of the porous carbon anode material.

[0057] In some embodiments, the mass ratio of the carbon particle precursor to the binder in step (1) is 1:(0.05-0.5); preferably 1:(0.1-0.3); for example, it can be 1:0.05, 1:0.1, 1:0.12, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, 1:0.45 or 1:0.5, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0058] It should be noted that the present invention controls the mass ratio of carbon particle precursor to binder within the range of 1:(0.05-0.5), which can ensure the crush strength of porous carbon materials and avoid the problem of reduced electron and ion transport efficiency caused by having too much carbon particle precursor compared to binder.

[0059] In some embodiments, the particle size D of the soft carbon particle precursor in step (1) V 50 represents 2μm-5μm, for example, it can be 2μm, 3μm, 4μm or 5μm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0060] It should be noted that the carbon particle size D selected in this invention is... V The tail powder with a size of 2μm-5μm was recycled and reused, avoiding resource waste, reducing the cost of porous carbon materials, and making it possible for the large-scale application of porous carbon anode materials in lithium-ion batteries.

[0061] In some embodiments, the adhesive comprises any one or a combination of at least two of asphalt, tar, phenolic resin, epoxy resin, or furan resin.

[0062] It should be noted that the adhesive of the present invention can be solid or liquid. When the adhesive is a liquid thermosetting resin such as phenolic resin, epoxy resin or furan resin, the method for preparing porous carbon further includes curing after mixing and granulation in step (1) and before carbonization.

[0063] For example, the curing step includes: drying the granulated product at 80℃-90℃, for example, 80℃, 82℃, 84℃, 86℃, 88℃ or 90℃ for 2h-4h, for example, 2h, 2.5h, 3h, 3.5h or 4h, and then continuing to heat to 110℃-120℃, for example, 110℃, 112℃, 114℃, 116℃, 118℃ or 120℃, and drying for 8h-10h, for example, 8h, 8.5h, 9h, 9.5h or 10h, but not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0064] In some embodiments, the carbon particle precursor in step (1) is a soft carbon particle precursor.

[0065] In some embodiments, the soft carbon particle precursor includes any one or a combination of at least two of petroleum coke, pitch coke, or coal coke.

[0066] In some embodiments, the mass ratio of the porous carbon precursor to the solid activator in step (2) is (0.8-1.8):2; preferably (1-1.5):2; for example, it can be 0.8:2, 1.0:2, 1:2, 1.2:2 or 1.5:2, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0067] In some embodiments, the space velocity of the vapor is 0.1 mL / g / s to 0.22 mL / g / s; preferably 0.14 mL / g / s to 0.18 mL / g / s; for example, it can be 0.1 mL / g / s, 0.11 mL / g / s, 0.12 mL / g / s, 0.13 mL / g / s, 0.14 mL / g / s, 0.15 mL / g / s, 0.16 mL / g / s, 0.17 mL / g / s, 0.18 mL / g / s, 0.19 mL / g / s, 0.20 mL / g / s, 0.21 mL / g / s or 0.22 mL / g / s, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0068] In some embodiments, the temperature of the co-activation treatment in step (2) is 800℃-900℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃ or 900℃, and the time is 3h-4h, for example, it can be 3h, 3.2h, 3.4h, 3.6h, 3.8h or 4h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0069] The steam described in this invention is introduced when the temperature of the co-activation treatment reaches 800℃-900℃.

[0070] In some embodiments, the heating rate of the co-activation treatment in step (2) is 3℃ / min-5℃ / min, for example, it can be 3℃ / min, 3.5℃ / min, 4℃ / min, 4.5℃ / min or 5℃ / min, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0071] In some embodiments, the co-activation treatment in step (2) is carried out in a protective gas, which includes nitrogen.

[0072] In some embodiments, the granulation method in step (1) includes kneading.

[0073] In some embodiments, the granulation temperature in step (1) is 30℃-50℃, for example, it can be 30℃, 35℃, 40℃, 45℃ or 50℃, and the time is 4h-6h, for example, it can be 4h, 4.5h, 5h, 5.5h or 6h, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0074] In some embodiments, the carbonization temperature in step (1) is 800℃-900℃, for example, it can be 800℃, 820℃, 840℃, 860℃, 880℃ or 900℃, and the time is 2h-3h, for example, it can be 2h, 2.5h or 3h, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0075] In some embodiments, a crushing step is performed after the carbonization process described in step (1) prior to step (2).

[0076] In some embodiments, the crushing yields a particle size D V 50 refers to crushed material with a diameter of 5μm-20μm, such as 5μm, 10μm, 15μm or 20μm, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0077] In the third embodiment, a negative electrode material is provided, which is obtained by carbon coating using the porous carbon material described in the first embodiment and the porous carbon material prepared by the preparation method described in the second embodiment.

[0078] In the fourth embodiment, a secondary battery is provided, which includes the negative electrode material as described in the third embodiment.

[0079] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0080] Example 1

[0081] This embodiment provides a porous carbon material and its preparation method. The preparation method of the porous carbon material includes the following steps:

[0082] (1) After mixing petroleum coke and liquid phenolic resin evenly, place them into a kneading pot and knead at 40°C for 5 hours to obtain a mixture.

[0083] In the petroleum coke and liquid phenolic resin mixture, the mass ratio of petroleum coke to liquid phenolic resin is 1:0.17.

[0084] The particle size D of the petroleum coke V 50 represents 5μm;

[0085] (2) Spread the mixture described in step (1) on a polytetrafluoroethylene film, place it in an oven and bake at 85°C for 3 hours, then raise the temperature to 115°C and continue baking for 9 hours to obtain a cured material;

[0086] (3) After crushing the solidified material described in step (2), it is placed in an intermittent rotary kiln for carbonization treatment. The carbonization temperature is 850℃ and the carbonization time is 2.5h to obtain carbonized material.

[0087] (4) Use a universal crusher to crush the carbonized material obtained in step (3) to obtain a particle size D. V 50 refers to crushed material with a diameter of 10.1 μm;

[0088] (5) The crushed material obtained in step (4) is subjected to pore formation using an alkali-steam co-activation method. Specifically, the crushed material is uniformly mixed with KOH at a mass ratio of 1:2. After mixing, the mixture is placed in a rotary kiln under N2 protection and heated to 850°C at a heating rate of 4°C / min. Water vapor is then introduced, with a water vapor space velocity of 0.16 mL / g / s. After holding at 850°C for 3.5 hours, the porous carbon material is obtained. The SEM image of the porous carbon material is shown below. Figure 1 As shown, by Figure 1 It can be seen that the material exhibits obvious agglomeration after the granulation process of this invention, and the material is evenly distributed, proving that the granulation process is successful.

[0089] The pore size distribution diagram of the porous carbon material described in this embodiment is as follows: Figure 2 As shown, by Figure 2 It is known that the pore size of the material is mainly distributed in the range of 0.1nm-4nm. This pore structure can increase the specific surface area of ​​the material, expose more active sites, and improve the transport efficiency of electrolyte, ions and electrons.

[0090] Example 2

[0091] This embodiment provides a porous carbon material and its preparation method. The preparation method of the porous carbon material includes the following steps:

[0092] (1) After mixing petroleum coke and liquid phenolic resin evenly, place them into a kneading pot and knead at 50°C for 4 hours to obtain a mixture.

[0093] In the petroleum coke and liquid phenolic resin mixture, the mass ratio of petroleum coke to liquid phenolic resin is 1:0.1.

[0094] The particle size D of the petroleum coke V 50 is 2μm;

[0095] (2) Spread the mixture described in step (1) on a polytetrafluoroethylene film, place it in an oven and bake at 80°C for 4 hours, then raise the temperature to 120°C and continue baking for 8 hours to obtain a cured material;

[0096] (3) After crushing the solidified material described in step (2), it is placed in an intermittent rotary kiln for carbonization treatment. The carbonization temperature is 900℃ and the carbonization time is 2h to obtain carbonized material.

[0097] (4) Use a universal crusher to crush the carbonized material obtained in step (3) to obtain a particle size D. V 50 refers to crushed material with a diameter of 9.2 μm;

[0098] (5) The crushed material described in step (4) is activated by alkali-steam co-activation to create pores. Specifically, the crushed material is mixed with KOH at a mass ratio of 1:2. After mixing, the mixture is placed in a rotary kiln and heated to 800°C at a heating rate of 3°C / min under N2 protection. Water vapor is introduced with a space velocity of 0.14 mL / g / s. After holding at 800°C for 4 hours, the porous carbon material is obtained.

[0099] Example 3

[0100] This embodiment provides a porous carbon material and its preparation method. The preparation method of the porous carbon material includes the following steps:

[0101] (1) After mixing petroleum coke and liquid phenolic resin evenly, place them into a kneading pot and knead at 30°C for 6 hours to obtain a mixture.

[0102] In the petroleum coke and liquid phenolic resin mixture, the mass ratio of petroleum coke to liquid phenolic resin is 1:0.3.

[0103] The particle size D of the petroleum coke V 50 represents 5μm;

[0104] (2) Spread the mixture described in step (1) on a polytetrafluoroethylene film, place it in an oven and bake at 90°C for 2 hours, then raise the temperature to 110°C and continue baking for 10 hours to obtain a cured material;

[0105] (3) After crushing the solidified material described in step (2), it is placed in an intermittent rotary kiln for carbonization treatment. The carbonization temperature is 800℃ and the carbonization time is 3h to obtain carbonized material.

[0106] (4) Use a universal crusher to crush the carbonized material obtained in step (3) to obtain a particle size D. V 50 refers to crushed material with a diameter of 10.8μm;

[0107] (5) The crushed material described in step (4) is pore-forming using an alkali-steam co-activation method. Specifically, the crushed material is uniformly mixed with KOH at a mass ratio of 1.5:2. After mixing, the mixture is placed in a rotary kiln and heated to 900°C at a heating rate of 5°C / min under N2 protection. Water vapor is then introduced, with a water vapor space velocity of 0.18 mL / g / s. After holding at 900°C for 3 hours, the porous carbon material is obtained.

[0108] Example 4

[0109] This embodiment provides a porous carbon material. In the preparation method of the porous carbon material, except that in step (1), the mass ratio of petroleum coke to liquid phenolic resin is 1:0.05, the rest is the same as in Example 1.

[0110] Example 5

[0111] This embodiment provides a porous carbon material. In the preparation method of the porous carbon material, except that in step (1), the mass ratio of petroleum coke to liquid phenolic resin is 1:0.5, the rest is the same as in Example 1.

[0112] Example 6

[0113] This embodiment provides a porous carbon material. The preparation method of the porous carbon material is the same as that in Example 1, except that the space velocity of water vapor in step (5) is 0.1 mL / g / s.

[0114] Example 7

[0115] This embodiment provides a porous carbon material. The preparation method of the porous carbon material is the same as that in Example 1, except that the space velocity of water vapor in step (5) is 0.22 mL / g / s.

[0116] Example 8

[0117] This embodiment provides a porous carbon material. The preparation method of the porous carbon material is the same as that in Example 1, except that the mass ratio of crushed material to KOH in step (5) is 0.8:2.

[0118] Example 9

[0119] This embodiment provides a porous carbon material. The preparation method of the porous carbon material is the same as that in Example 1, except that the mass ratio of crushed material to KOH in step (5) is 1.8:2.

[0120] Comparative Example 1

[0121] This comparative example provides a porous carbon material, the preparation method of which includes the following steps:

[0122] (1) The particle size D V 50 μm of petroleum coke was placed in an intermittent rotary kiln for carbonization treatment at a temperature of 850°C for 2.5 hours to obtain carbonized material.

[0123] (2) Use a universal crusher to crush the carbonized material obtained in step (1) to obtain a particle size D. V 50 refers to crushed material with a diameter of 5μm;

[0124] (3) The crushed material described in step (2) is activated by alkali-steam co-activation to create pores. Specifically, the crushed material is mixed with KOH at a mass ratio of 1:2. After mixing, the mixture is placed in a rotary kiln and heated to 850°C at a heating rate of 4°C / min under N2 protection. Water vapor is then introduced with a space velocity of 0.16 mL / g / s. The mixture is kept at 850°C for 3.5 hours to obtain the porous carbon material.

[0125] Comparative Example 2

[0126] This comparative example provides a porous carbon material, the preparation method of which includes the following steps:

[0127] (1) The particle size D V 50 μm of petroleum coke was placed in an intermittent rotary kiln for carbonization treatment at a temperature of 850°C for 2.5 hours to obtain carbonized material.

[0128] (2) Use a universal crusher to crush the carbonized material described in step (1) to obtain crushed material with a particle size Dv50 of 10μm;

[0129] (3) The crushed material described in step (2) is activated by alkali-steam co-activation to create pores. Specifically, the crushed material is mixed with KOH at a mass ratio of 1:2. After mixing, the mixture is placed in a rotary kiln and heated to 850°C at a heating rate of 4°C / min under N2 protection. Water vapor is then introduced with a space velocity of 0.16 mL / g / s. The mixture is kept at 850°C for 3.5 hours to obtain the porous carbon material.

[0130] Comparative Example 3

[0131] This comparative example provides a porous carbon material. The preparation method of the porous carbon material is the same as that of Example 1, except that step (5) only uses the alkali activation method to create pores and water vapor is not introduced in step (5) to change the adaptability of the obtained porous carbon material.

[0132] Comparative Example 4

[0133] This comparative example provides a porous carbon material. The preparation method of the porous carbon material is the same as that of Example 1, except that step (5) only uses steam activation to create pores and no alkali is added in step (5) to change the adaptability of the obtained porous carbon material.

[0134] The specific surface area, total pore volume, mesoporous and microporous porosity, crushing strength, and particle size D of the porous carbon materials obtained in the above embodiments and comparative examples are as follows: V 50 is shown in Table 1.

[0135] The test methods for specific surface area, total pore volume, and mesopore and micropore porosity are as follows: according to GB / T 19587-2004, the test is conducted using a Micromeritics Tristar 3000 specific surface area tester. The test conditions are as follows: after the obtained porous carbon material is degassed in a vacuum environment at 200℃ for 6 hours, nitrogen adsorption-desorption test is performed at -196℃.

[0136] The crush strength test method is as follows: the test is conducted in accordance with GB / T 43091-2023 using the SPFT1000 single-particle mechanical property testing system from Yuaneng Technology.

[0137] Particle size D V The test method for 50 is as follows: particle size is measured using Mastersizer 3000 laser diffraction technology. Based on the particle size distribution laser diffraction method GB / T19077-2016, the particle size distribution of the modified graphite material sample is measured. V 50: The particle size at which the cumulative particle size distribution percentage of a sample reaches 50%. Physically, it means that 50% of the particles are larger than this value, and 50% are smaller. (D) V 50 is also called the median particle size.

[0138] The porous carbon materials obtained in the above embodiments and comparative examples were used to prepare a negative electrode material. The preparation method included the following steps: using a 10% volume fraction acetylene mixed gas (acetylene + argon) as a coating agent, the porous carbon materials described in the above embodiments and comparative examples were placed in a CVD furnace, and heated to 500°C at a heating rate of 3°C / min under a N2 atmosphere. After reaching the target temperature, the nitrogen gas was turned off, and a 10% acetylene mixed gas was introduced at a flow rate of 1.5 L / min. The temperature was maintained for 14 hours, and after cooling, the target sample was taken out to obtain the porous carbon negative electrode material. The negative electrode material was then used to prepare a battery. The preparation method included: combining the above-obtained negative electrode material with carboxymethyl cellulose (CMC) binder, styrene-butadiene rubber (SBR) and conductive agent Super P is mixed in water at a mass ratio of 8:0.5:0.5:1 to form a slurry, which is then uniformly coated onto copper foil to form a negative electrode sheet with a thickness of about 100 μm. After the coated electrode sheet is cut, it is vacuum dried at 60 °C for 12 h to obtain a porous carbon negative electrode sheet. Lithium foil is used as the counter electrode, Celgard 2320 microporous polypropylene film is used as the separator, and 1.0 mol / L LiPF6 ethyl carbonate / dimethyl carbonate solution is used as the electrolyte. The cells are assembled into a button cell in an argon atmosphere.

[0139] Electrochemical performance tests were conducted on the battery, including initial efficiency, reversible capacity, and rate performance tests.

[0140] First-cycle efficiency and reversible capacity testing: After aging the assembled coin cells for 6 hours, electrochemical tests were conducted on the Blue Electric CT3002A charge-discharge testing system at room temperature. The cells were discharged at a rate of 0.05C to the cutoff voltage of 0V, allowed to stand for 10 minutes, and then charged at a rate of 0.05C to the cutoff voltage of 2V. This cycle was repeated 5 times. The discharge capacity was recorded as the reversible capacity. The first-cycle efficiency, or first-cycle efficiency, was obtained by dividing the discharge capacity by the charge capacity. The test results are shown in Table 2.

[0141] Rate performance testing: After aging the assembled coin cells for 6 hours, electrochemical tests were conducted on the Blue Electric CT3002A charge-discharge testing system at room temperature. The rate test conditions were as follows: ① Discharge from 0.05C to 0.005V and rest for 30 minutes; charge from 0.05C to 2V and rest for 30 minutes; ② Discharge from 1C to 0.005V and rest for 30 minutes; charge from 1C to 2V and rest for 30 minutes; ③ Discharge from 2C to 0.005V and rest for 30 minutes; charge from 2C to 2V and rest for 30 minutes. This allows the rate performance (2C / 0.05C) to be tested. The rate performance is calculated as the specific discharge capacity of the battery at 2C current / the discharge capacity of the battery at 0.05C current × 100%. The results are recorded in Table 2.

[0142] Table 1

[0143]

[0144]

[0145] Table 2

[0146]

[0147]

[0148] As can be seen from Tables 1 and 2:

[0149] As shown in Examples 1 and Comparative Examples 1-2, compared to porous carbon materials prepared using only carbon particle precursors, the secondary particle porous carbon material formed by bonding carbon particle precursors according to the present invention has higher strength, resulting in less capacity and first-efficiency loss due to low strength during rolling, thus improving the battery's first-efficiency, capacity, and rate performance. As shown in Examples 1 and Comparative Examples 3-4, the present invention preferably uses a steam and alkali co-activation method, which makes it easier to obtain porous carbon materials with excellent performance. As shown in Examples 1 and Examples 4-5, the mass ratio of the binder in the structure of the secondary particle porous carbon of the present invention can further affect the strength of the porous carbon material, as well as the battery's capacity, first-efficiency, and rate performance. As shown in Examples 1 and Examples 6-9, during co-activation of the present invention, the steam flow rate and the amount of solid-phase activator added will affect the pore structure of the porous carbon material, thereby affecting the battery's performance.

[0150] In summary, this invention provides a porous carbon material, its preparation method, an anode material, and a secondary battery. The preparation method involves mixing a carbon particle precursor with a binder, followed by mixing, granulation, and carbonization treatment to obtain a porous carbon precursor with good compressive strength. Furthermore, a co-activation method is employed to create pores in the porous carbon precursor, fully leveraging the synergistic effect of the solid-phase activator and activator vapor. This results in a porous carbon material with abundant micropores and mesopores, as well as high strength. When applied to lithium-ion batteries, this effectively improves the capacity, initial efficiency, and rate performance of the porous carbon anode material.

[0151] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A porous carbon material, characterized by, The porous carbon material is granular, and includes a secondary particle structure formed by bonding several amorphous carbon particles; the mesoporosity of the porous carbon material is 10%-40%, the microporosity is 60%-90%, and the compressive strength of the porous carbon material is 20mN-40mN.

2. The porous carbon material according to claim 1, characterized in that, The porous carbon material has a mesoporous rate of 20%-30% and a microporous rate of 70%-80%. Preferably, the compressive strength of the porous carbon is 30mN-40mN; Preferably, the specific surface area of the porous carbon material is 1800 m 2 / g - 2200 m 2 / g; Preferably, the total pore volume of the porous carbon material is 0.8 cm 3 / g-1.2 cm 3 / g; Preferably, the particle size D of the porous carbon material is... V 50 represents 5μm-20μm.

3. A method for producing a porous carbon material, characterized by, The preparation method includes the following steps: (1) After mixing the carbon particle precursor with the binder, the carbon particles are granulated and carbonized sequentially to obtain a porous carbon precursor. (2) The porous carbon precursor and the solid activator are mixed and then co-activated by activator steam to obtain the porous carbon material.

4. The production method according to claim 3, characterized by, The mass ratio of the carbon particle precursor to the binder in step (1) is 1:(0.05-0.5); Preferably, the mass ratio of the carbon particle precursor to the binder in step (1) is 1:(0.1-0.3); Preferably, the particle size D of the carbon particle precursor in step (1) V 50 is 2-5 μm; Preferably, the adhesive in step (1) comprises any one or a combination of at least two of asphalt, tar, phenolic resin, epoxy resin or furan resin; Preferably, the carbon particle precursor in step (1) is a soft carbon particle precursor; Preferably, the soft carbon particle precursor includes any one or a combination of at least two of petroleum coke, pitch coke, or coal coke.

5. The preparation method according to claim 3, characterized in that, The mass ratio of the porous carbon precursor to the solid-phase activator in step (2) is (0.8-1.8):2; Preferably, the mass ratio of the porous carbon precursor to the solid-phase activator in step (2) is (1-1.5):2; Preferably, the flow rate of the activator vapor in step (2) is 0.1 mL / g / s to 0.22 mL / g / s; Preferably, the flow rate of the activator vapor in step (2) is 0.14 mL / g / s to 0.18 mL / g / s.

6. The preparation method according to any one of claims 3-5, characterized in that, The co-activation treatment in step (2) is carried out at a temperature of 800℃-900℃ for 3-4 hours. Preferably, the heating rate of the co-activation treatment in step (2) is 3℃ / min-5℃ / min; Preferably, the co-activation treatment in step (2) is carried out in a protective gas.

7. The method of any one of claims 3-6, wherein, The granulation method described in step (1) includes kneading; Preferably, the granulation temperature in step (1) is 30℃-50℃ and the time is 4h-6h.

8. The method of any one of claims 3-7, wherein, The carbonization temperature in step (1) is 800℃-900℃, and the time is 2h-3h.

9. A negative electrode material, characterized by, The negative electrode material is obtained by carbon coating the porous carbon material as described in claim 1 or 2 and the porous carbon material prepared by any one of the preparation methods in claims 3-8.

10. A secondary battery characterized by comprising: The secondary battery includes the negative electrode material as described in claim 9.

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