Reclaimed graphite fast charging material and preparation and application thereof

Abstract

The application belongs to the field of graphite recycling, and particularly relates to a regenerated graphite fast-charging material. Waste graphite raw materials are subjected to pre-oxidation treatment to obtain pre-oxidized graphite. The pre-oxidized graphite and a combined treatment agent are mixed and subjected to heat treatment at a temperature of 1500-2000 DEG C to obtain a heat-treated material. The combined treatment agent comprises treatment agent A and treatment agent B. The treatment agent A is MCln, and the treatment agent B is a compound of formula 1. The heat-treated material is mixed with a carbon source and carbonized to obtain carbon-coated material. The carbon-coated material is mixed with a composite modifier to obtain the regenerated graphite fast-charging material. The composite modifier comprises a high-molecular resin, formula 2, formula 3 and formula 4. The application further comprises a material prepared by the method and an application thereof. The method can regenerate a high-rate regenerated graphite material.

Description

Technical Field

[0001] The invention belongs to the field of waste graphite regeneration, and particularly relates to repairing waste graphite into fast-filling graphite material. Background Art

[0002] Graphite, due to its unique thermal and electrical properties, has a wide range of applications in numerous fields. With the rapid development of new energy vehicles, waste graphite production has been increasing year by year. Recycling and refining waste graphite is crucial for the green and high-quality development of the graphite industry. However, graphite mineral resources are scarce, and artificial graphite synthesis requires high energy consumption. Therefore, regenerating graphite materials from waste graphite is an effective method.

[0003] Industries that can produce waste graphite mainly include waste batteries, waste photovoltaics and other industries; existing technologies mainly regenerate graphite from waste batteries, and the main means of regeneration are impurity removal and carbon coating.

[0004] For example, Chinese patent document CN118198570A discloses a high-rate recycled graphite negative electrode material, its preparation method, and application. It specifically describes that the graphite material of waste batteries is disassembled and peeled, then calcined and purified under medium-high temperature conditions, and then compounded with modified phenolic resin and non-ionic surfactant for carbon coating treatment.

[0005] For example, Chinese patent publication CN115275416A discloses a method for recovering graphite from waste lithium-ion batteries and a high-capacity, fast-charging negative electrode material. The document specifically describes a process for recovering waste graphite by particle size and interlayer separation. Chinese patent publication CN107959077A discloses a method for preparing a high-rate, high-safety nickel-cobalt-manganese oxide ternary material. The document specifically describes processes for pre-treating, impurity removal, heat treatment, and refinement of the waste graphite.

[0006] In summary, the existing technology mainly focuses on the recycling and regeneration of waste battery graphite materials, and the process universality is not ideal. In addition, the existing recycled materials are difficult to achieve fast charging application requirements with a rate of more than 6C. Summary of the Invention

[0007] In response to the problem that waste graphite-based recycled materials have poor process adaptability and are difficult to adapt to fast charging requirements above 6C, the present invention provides a recycled graphite fast charging material, aiming to improve the process adaptability and prepare recycled graphite materials that meet fast charging requirements above 6C.

[0008] The second purpose of the present invention is to provide a regenerated graphite fast-charging material obtained by the preparation method and its application in secondary batteries.

[0009] The third object of the present invention is to provide a secondary battery comprising the regenerated graphite fast-charging material.

[0010] A regenerated graphite fast-charging material, comprising the following steps:

[0011] Step (1):

[0012] The waste graphite raw material is pre-oxidized to obtain pre-oxidized graphite; the pre-oxidized graphite and the combined treatment agent are mixed and heat-treated at a temperature of 1500 to 2000° C. to obtain a heat-treated material;

[0013] The combined treatment agent comprises treatment agent A and treatment agent B, wherein treatment agent A is MCln and treatment agent B is a compound of formula 1;

[0014] The M is at least one of Na, K, Li, Mg, and Ca; the n is the valence of M;

[0015]

[0016] The R1 is a carbon chain with a substituent, wherein the substituent contains at least F and Cl; the X is H, Li, Na, K, NH4 or a C1-C6 alkyl group;

[0017] Step (2):

[0018] The heat-treated material and the carbon source are mixed and carbonized to obtain a carbon-coated material; the carbon-coated material is then mixed and modified with a composite modifier to obtain the regenerated graphite fast-charging material;

[0019] The composite modifier includes a polymer resin, formula 2, formula 3 and formula 4;

[0020]

[0021] The R2 is C1~C 20 An alkyl or aryl group, wherein the alkyl or aryl group is allowed to have a substituent, and the substituent is at least one of a C1-C6 alkyl group, a C1-C6 alkoxy group, an aryl group, a carboxylic acid group, an ester group, and a halogen group;

[0022] The R3 to R6 are independently C1 to C6 alkyl, aryl, phosphate or phospholipid groups, or any two substituents are cyclized to form a ring with five or more members;

[0023] The R7~R 10 In the formula (a), at least one substituent is F, and the other substituents are H, halogen, C1-C6 alkyl or aryl.

[0024] Waste graphite contains many electrochemically unfavorable impurities, and the surface and deep conductive networks are damaged, making it difficult to reconstruct. Although the existing technology has some purification and carbon coating repair processes, it is difficult to deeply optimize the physical and chemical structure of graphite with existing means, it is difficult to reconstruct the deep conductive network and ion transmission path, and it is difficult to adapt to the fast charging requirements of more than 6C. In response to this problem, the present invention has conducted in-depth research and innovatively pre-oxidized waste graphite, and used the combined treatment agent for heat treatment, and further coordinated with carbon coating and subsequent quaternary composite modifiers for joint modification, so that synergy can be achieved and impurities can be deeply purified. In addition, it can also deeply optimize and reconstruct the electronic and ion conduction networks, so that it can meet the high fast charging requirements of more than 6C.

[0025] The technical solution of the present invention has good adaptability. For example, the waste graphite raw material can be graphite-containing waste recovered from at least one of waste batteries, waste photovoltaic materials, waste graphite crucibles, etc.

[0026] Preferably, the graphite content in the waste graphite raw material is above 82-98%, and can further be 93-98%.

[0027] In the present invention, the waste graphite may be pre-oxidized. As an optional solution, the waste graphite raw material may be placed in an oxygen-containing atmosphere and kept at a temperature of 300-500° C. for pre-oxidation.

[0028] In the present invention, the oxygen-containing atmosphere may be, for example, at least one of air and oxygen.

[0029] In the present invention, the pre-oxidation time is 0.5 to 2 hours, and can further be 1 to 2 hours.

[0030] In the present invention, the D50 of the pre-oxidized graphite is controlled to be 6 to 8 μm.

[0031] In the present invention, pre-oxidized graphite is innovatively heat-treated in a synergistic combined system containing components A and B. Based on the joint control of the type of component A and the structure of component B, and further coordinated with the control of the temperature, the physical and chemical structure of graphite can be comprehensively unblocked and optimized based on the three-phase action of gas, solid and liquid, which is beneficial to the combination with subsequent processes, the ion and electron conduction pathways and paths, and the fast charging performance of the obtained regenerated graphite material can be optimized.

[0032] In the combined treatment agent of the present invention, in component A, M is Na and K. Studies have shown that this preferred combination further enhances the high-rate performance of the prepared regenerated graphite material. In this preferred embodiment, the weight ratio of NaCl to KCl is not particularly limited, and can be, for example, 1:0.5-2.

[0033] In the component B, the formula 1 is a compound of formula 1-A;

[0034]

[0035] The R is H, C1-C3 alkyl, halogen or halogenated alkyl; the X is H, Li, Na, K or NH4;

[0036] Preferably, in the combined treatment agent, the weight ratio of component A to component B is 0.5-5:0.1-2; further, it can be 2-4:1-2.

[0037] Preferably, the weight ratio of the pre-oxidized graphite to the combined treatment agent is 1:0.5-7; further, it can be 1:2.5-6.5.

[0038] Preferably, the atmosphere of the heat treatment is a protective atmosphere, further at least one of nitrogen and an inert gas.

[0039] Preferably, the holding time at the heat treatment temperature is 2 to 10 hours, and further can be 2 to 5 hours.

[0040] Preferably, the heat treatment process includes a two-stage gradient process, wherein the temperature of the first holding stage is 700-900°C for 1-3 hours, and the temperature of the second holding stage is 1600-1850°C for 2-4 hours. Research in the present invention shows that the combination of components A and B, further combined with the preferred heat treatment process, can further optimize the physicochemical structure of the regenerated graphite material, helping to further enhance the high-rate performance of the prepared regenerated graphite.

[0041] More preferably, the second holding stage is carried out under negative pressure, and the negative pressure can be, for example, below 250 Pa. Studies in the present invention have shown that the two-stage gradient treatment, combined with the negative pressure treatment, can help further enhance the high-rate performance of the prepared regenerated graphite.

[0042] In the present invention, the heat-treated material may be subjected to conventional treatment. For example, as an optional solution, in step (2), the carbon source includes at least one of asphalt and resin.

[0043] The resin may be, for example, at least one of phenolic resin, petroleum resin and epoxy resin.

[0044] Furthermore, the amount of carbon source added is 1-10% of the weight of the heat-treated material, and further can be 2-5%.

[0045] Preferably, the carbonization temperature is 1000-1400°C.

[0046] Preferably, the holding time at the carbonization temperature is 1 to 6 hours, and further can be 4 to 5 hours.

[0047] Preferably, the median particle size of the carbonized material is controlled to be 8 to 15 μm, and further can be 9.5 to 13.5 μm.

[0048] In the present invention, the carbon coating material is composite-modified using a composite modifier including a polymer resin, Formula 2, Formula 3, and Formula 4. This is beneficial for synergizing with other processes to optimize the high-fast charging performance of the recycled material.

[0049] In the present invention, in step (3), the polymer resin is a water-soluble resin, preferably at least one of epoxy water-based resin, polyurethane resin, water-soluble phenolic resin or water-soluble polyester resin.

[0050] Preferably, in the R3 to R6 of Formula 3, at least one substituent is a phosphate group or a phosphoester group, or a phosphonic acid complex.

[0051] For example, the formula 3 may be at least one of the compounds of the following structures:

[0052]

[0053] In formula 3-A to formula 3-C, the R 11 、R 12 、R 13 is an alkyl group alone, further, said R 11 、R12 alone is C5~ 10 The alkyl group, the R 13 It is a C1-C5 alkyl group.

[0054] Preferably, the formula 3 comprises at least one of formula 3-A-1, formula 3-B-1, and formula 3-C-1;

[0055]

[0056]

[0057] Preferably, in the formula 4, R7 to R 10 1 to 3 substituents are F, and the other substituents are H, C1 to C6 alkyl or phenyl.

[0058] In step (3), the weight ratio of the carbon coating material and the polymer resin in the composite modifier, formula 2, formula 3 and formula 4 is 100:5-8:0.01-0.5:0.005-0.05:0.02-0.1; further 100:5-6:0.2-0.3:0.01-0.03:0.05-0.08.

[0059] In the present invention, during the modification process, the carbon coating material and the composite modifier can be mixed by a wet method and then subjected to a desolventizing treatment; the solvent is water, alcohol, or a mixed solution of water and alcohol.

[0060] In the present invention, the modified system can be subjected to a desolventizing treatment to obtain the material, and the desolventizing means is, for example, a spraying treatment.

[0061] The present invention also provides a regenerated graphite fast-filling material prepared by the preparation method.

[0062] The preparation method described in the present invention can give the regenerated graphite special physical and chemical characteristics, and the material with the physical and chemical characteristics can unexpectedly achieve a regenerated graphite of more than 6C, and further can reach a fast charging requirement of up to 9 to 12C.

[0063] The present invention also provides an application of the regenerated graphite fast-charging material, which is used as a negative electrode active material to prepare a secondary battery.

[0064] The present invention can use the regenerated graphite fast-charging material of the present invention as a negative electrode active material based on known means and methods to prepare a desired secondary battery.

[0065] The present invention also provides a secondary battery comprising the regenerated graphite fast-charging material prepared by the preparation method.

[0066] The secondary battery of the present invention, in addition to comprising the regenerated graphite fast-charging material of the present invention, may have other components and structural parts that are well-known.

[0067] In the present invention, the secondary battery can be a lithium ion secondary battery, a sodium ion secondary battery or a potassium ion secondary battery.

[0068] Beneficial effects

[0069] The present invention innovatively pre-oxidizes waste graphite and uses the combined treatment agent for heat treatment, and further cooperates with carbon coating and subsequent quaternary composite modifier for joint modification. This can achieve synergy and deeply purify impurities. In addition, it can also deeply optimize and reconstruct the electronic and ion conduction network, so that it can meet the high fast charging requirements of more than 6C; for example, the research of the present invention shows that the recycled material can achieve fast charging under 10C conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0070] Attachment Figure 1 This is the SEM image of the material obtained in Example 1;

[0071] Attachment Figure 2 This is the first cycle diagram of the material obtained in Example 1 assembled into a button;

[0072] Attachment Figure 3 This is a diagram of the full capacity retention rate of the material assembly obtained in Example 1. DETAILED DESCRIPTION

[0073] The following examples illustrate the specific steps of the present invention. It should be understood that these examples are only for illustration of the present invention and are not intended to limit the scope of the present invention in any way. Various processes and methods not described in detail in the present invention are conventional methods well known in the art.

[0074] An optional solution of the present invention may include the following steps:

[0075] Step 1, pre-oxidation treatment:

[0076] placing the waste graphite material in an air atmosphere for pretreatment;

[0077] The treatment temperature is 300-500°C, the treatment time is 0.5-2h, and the D50 after air oxidation treatment is controlled at 6-8μm;

[0078] Step 2: In-situ directional purification:

[0079] The graphite powder obtained by pretreatment is mixed evenly with the combined treatment agent (component A and component B), and then placed in an atmosphere furnace for heat treatment;

[0080] The component A is MCln, and the component B is a compound of formula 1; the mass ratio of graphite to component A is 100:0.5-5; the mass ratio of graphite to auxiliary component B is 100:0.1-2; the heat treatment atmosphere is one or more of nitrogen, argon, and helium, the heat treatment temperature is 1500-2000°C, and the treatment time is 2-5 hours.

[0081] Step 3: Surface carbon coating: Granulation with a binder followed by carbonization.

[0082] The binder refers to any one of asphalt (softening point 180-250°C), phenolic resin, petroleum resin and epoxy resin; the asphalt addition amount is 1-5%; the phenolic resin addition amount is 1%-3%; the petroleum resin addition amount is 1-2%; the epoxy resin addition amount is 1-4%; the carbonization temperature is 1000-1400°C, and the carbonization time is 1-6h; the material with a median particle size of 9.5-13.5μm is obtained.

[0083] Step 4, surface modification treatment: the carbonized material, formula 4, formula 2, and formula 3 are mixed, dispersed in a water-soluble resin, ultrasonically dispersed evenly, and spray-dried to obtain a graphite composite negative electrode material.

[0084] The mass ratio of the carbonized material: formula 4 is 100:0.02-0.1; the mass ratio of the carbonized material: formula 2 is 100:0.01-0.5; the mass ratio of the carbonized material: formula 3 is 100:0.005-0.05; and the mass ratio of the carbonized material to the water-soluble resin is 100:5-8.

[0085] The waste graphite of the invention comes from graphite powder obtained by crushing and sorting waste lithium batteries, and the graphite carbon content of the graphite powder is 95±2%.

[0086] Example 1

[0087] Step 1: waste graphite powder is placed in a muffle furnace at 350°C, introduced into an air atmosphere, and kept warm for 1.5 hours. The powder is crushed and sieved to select powder with a D50 of 8 μm;

[0088] Step 2: The above powder is mixed with 2% by weight of component A (potassium chloride) and 1% by weight of component B (Formula 1a: ) after being mixed evenly, placed in an atmosphere furnace, under the protection of argon, heated to 1800°C at a rate of 5°C / min and kept warm for 3h to obtain the heat-treated material.

[0089] Step 3: Mix the heat-treated material from step 2 with 2% by weight of phenolic resin, place it in an atmosphere furnace, treat it at 1200°C for 4 hours under argon protection, crush and sieve it after cooling, and select powder with D50 of 13.5μm.

[0090] Step 4, the powder obtained in step 3, formula 4 (formula 4a: ), Formula 2 (lithium acetate), and Formula 3 (Formula 3-B-1) are mixed uniformly at a ratio of 100:0.05:0.2:0.01, and then dispersed in a water-soluble polyester resin (the mass ratio of the carbonized material to the water-soluble resin is 100:6, the solvent is water, and the concentration of the resin is 10%). After ultrasonic dispersion, the mixture is spray-dried in a spray dryer (the drying temperature is controlled at 150-250°C) to obtain a graphite composite negative electrode material.

[0091] Example 2

[0092] Compared with Example 1, the only difference is that component A is equal weight of potassium chloride + sodium chloride (mass ratio 1:1), wherein the weight of component A and other operations and conditions are the same as in Example 1.

[0093] Example 3

[0094] Compared with Example 1, the only difference is that component B is the same weight of formula 1b Other operations and conditions are the same as in Example 1.

[0095] Example 4

[0096] Compared with Example 1, the only difference is that the heat treatment in step 2 includes a two-stage gradient heat treatment process, the steps of which are: heating to 800°C at 3°C / min and keeping warm for 2h (first stage insulation), then heating to 1800°C at 5°C / min and keeping warm for 3h (second stage insulation), and other operations and conditions are the same as in Example 1.

[0097] Example 5

[0098] The difference from Example 4 is that in step 2, the system pressure is maintained at a negative pressure (below 200 Pa) during the second insulation stage, and the other operations and conditions are the same as those in Example 1.

[0099] Example 6

[0100] Compared with Example 1, the only difference is that in step 4, the formula 2 used is The dosage of formula 2 and other operations and conditions are the same as those in Example 1.

[0101] Example 7

[0102] Compared with Example 1, the only difference is that in step 4, Formula 4 is changed, and the experimental groups are:

[0103] Group A: Formula 4 is Formula 4b

[0104] Group B: Formula 4 is a mixture of Formula 4a and Formula 4b in a weight ratio of 1:1.

[0105] The dosage of formula 4 and other operations and parameters are the same as those in Example 1.

[0106] Example 8

[0107] Compared with Example 1, the only difference is that the following conditions are changed, specifically:

[0108] The waste graphite is high-purity graphite parts retired from the semiconductor industry, with a purity (fixed carbon content) of 97.1%.

[0109] Step 1: waste graphite powder is placed in a muffle furnace at 450°C, introduced into an air atmosphere, kept warm for 1 hour, crushed and sieved, and powder with a D50 of 6 μm is selected;

[0110] Step 2: Mix the above powder with 4% by weight of component A and 2% by weight of component B (Formula 1a), place it in an atmosphere furnace, and under argon protection, heat it to 1600° C. at 5° C. / min and keep it warm for 4 hours.

[0111] Step 3: Mix the heat-treated material from step 2 with 5% by weight of phenolic resin, place it in an atmosphere furnace, treat it at 1100°C for 5 hours under argon protection, crush and sieve it after cooling, and select powder with D50 of 14.1μm.

[0112] Step 4, the powder obtained in step 3, formula 4 (formula 4a), formula 2 (lithium acetate), and formula 3 (formula 3-A-1) are mixed uniformly at a ratio of 100:0.08:0.3:0.03, and then dispersed in a water-soluble polyester resin (the mass ratio of the carbonized material to the water-soluble resin is 100:5, the solvent is water, and the resin concentration is 8%). After ultrasonic dispersion, the mixture is spray-dried in a spray dryer (the drying temperature is controlled at 150-250°C) to obtain a graphite composite negative electrode material.

[0113] Comparative Example 1

[0114] Compared with Example 1, the only difference is that in step 1, nitrogen is used to replace the air, and other operations and parameters are the same as those in Example 1.

[0115] Comparative Example 2

[0116] Compared with Example 1, the only difference is that the component A in step 2 is changed, specifically, the component A is replaced by an equal weight of potassium hydroxide. Other operations and parameters are the same as in Example 1.

[0117] Comparative Example 3

[0118] Compared with Example 1, the only difference is that the component B in step 2 is changed, specifically, the component B is replaced by an equal weight of sodium acetate. Other operations and parameters are the same as in Example 1.

[0119] Comparative Example 4

[0120] Compared with Example 1, the only difference is that in step 4, lithium acetate is not added.

[0121] Other operations and parameters are the same as in Example 1.

[0122] Comparative Example 5

[0123] Compared with Example 1, the only difference is that in step 4, specifically, using equal weight As the above formula 4.

[0124] Other operations and parameters are the same as in Example 1.

[0125] Comparative Example 6

[0126] Compared with Example 1, the only difference is that Formula 3 is not added.

[0127] Other operations and parameters are the same as in Example 1.

[0128] Comparative Example 7

[0129] Compared with Example 1, the only difference is that step 4 is not performed, and the product of step 3 is directly used as the active material. Other operations and parameters are the same as those in Example 1.

[0130] Material electrochemical performance test:

[0131] The graphite product, binder (LA-133, CMC) and super carbon black of each case were mixed uniformly in a mass ratio of 92:3:3:2, and then water was added and stirred to form a uniform slurry. The slurry was coated on copper foil and placed in a vacuum dryer at 120°C for 12 hours to obtain a graphite negative electrode sheet.

[0132] The resulting negative electrode sheet is assembled with lithium to form a lithium half-cell, which is then assembled with a ternary positive electrode material (NCM523) to form a full cell. The ternary positive electrode material is prepared, for example, by mixing LiNi0.5Co0.2Mn0.3O2, conductive carbon black, and PVDF in a mass ratio of 8:1:1, adding NMP and stirring until a uniform slurry forms. The mixture is then coated on aluminum foil and vacuum-dried at 120°C for 12 hours to obtain the positive electrode sheet.

[0133] The separator used in the battery is Celgard2400, and the electrolyte is 1MLiPF6+EC / EMC / DMC (volume ratio 1:1:1).

[0134] The battery cycle performance was tested at room temperature with a test voltage range of 0.01V to 1.5V and a test rate of 10C. The results are shown in Table 1:

[0135] Table 1

[0136]

[0137] In summary, Examples 1-8 and Comparative Examples 1-7 demonstrate that the combination of the treatment components and processes described herein can achieve synergy and improve the performance of waste graphite-based materials at ultra-high rates. Furthermore, Examples 1 and 2 demonstrate that the use of the composite component A of the present invention, or a two-stage gradient heat treatment assisted by components A and B, particularly a negative pressure heat treatment, can further enhance the performance of waste-based materials at ultra-high rates. Examples 1 and 7 further demonstrate that the use of the combined Formula 4 described herein can further enhance the performance of waste-based materials at ultra-high rates.

Claims

1. A method for preparing a regenerated graphite fast-charging material, characterized in that the steps include: Step (1): Pre-oxidizing the waste graphite raw material to obtain pre-oxidized graphite; Then, the pre-oxidized graphite and the combined treatment agent are mixed and heat-treated at a temperature of 1500-2000° C. to obtain a heat-treated material; The combined treatment agent comprises treatment agent A and treatment agent B, wherein treatment agent A is MCln and treatment agent B is a compound of formula 1; The M is at least one of Na, K, Li, Mg, and Ca; the n is the valence of M; Formula 1 The R1 is a carbon chain with a substituent, wherein the substituent contains at least F and Cl; the X is H, Li, Na, K, NH4 or a C1-C6 alkyl group; Step (2): The heat-treated material and the carbon source are mixed and carbonized to obtain a carbon-coated material; the carbon-coated material is then mixed and modified with a composite modifier to obtain the regenerated graphite fast-charging material; The composite modifier includes a polymer resin, formula 2, formula 3 and formula 4; Formula 2 Formula 3 Formula 4 The R2 is C1~C 20 alkyl or aryl, or the alkyl or aryl has a substituent, and the substituent is at least one of a C1-C6 alkyl, a C1-C6 alkoxy, an aryl, a carboxylic acid, an ester group, and a halogen; R3 to R6 are independently C1 to C6 alkyl, aryl, phosphate or phospholipid groups, or any two of R3 to R6 are cyclized to form a five-membered or larger ring; The R7~R 10 Among them, at least one is F, and the others are H, halogen, C1~C6 alkyl or aryl; The polymer resin is a water-soluble resin.

2. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: The waste graphite raw material is graphite-containing waste material recovered from at least one of waste batteries, waste photovoltaic materials, and waste graphite crucibles.

3. The method for preparing the regenerated graphite fast-filling material according to claim 2, wherein: The graphite content in the waste graphite raw material is above 82-98%.

4. The method for preparing the regenerated graphite fast-charging material according to claim 1, wherein: The waste graphite raw material is placed in an oxygen-containing atmosphere and kept pre-oxidized at a temperature of 300-500°C.

5. The method for preparing the regenerated graphite fast-filling material according to claim 4, wherein: The pre-oxidation time is 0.5 to 2 hours.

6. The method for preparing the regenerated graphite fast-filling material according to claim 4, wherein: The D50 of pre-oxidized graphite is controlled at 6-8 μm.

7. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: In the combined treatment agent, in the treatment agent B, the formula 1 is a compound of formula 1~A; Formula 1~A The R is H, C1-C3 alkyl or halogen; the X is H, Li, Na, K or NH4.

8. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: In the combined treatment agent, the weight ratio of treatment agent A to treatment agent B is 0.5~5:0.1~2.

9. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: The weight ratio of the pre-oxidized graphite to the combined treatment agent is 1:0.5-7.

10. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: The heat treatment atmosphere is a protective atmosphere.

11. The method for preparing the regenerated graphite fast-filling material according to claim 10, wherein: The atmosphere of the heat treatment is at least one of nitrogen and an inert gas.

12. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: The holding time at the heat treatment temperature is 2 to 10 hours.

13. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: The heat treatment process includes two gradient processes, wherein the temperature of the first holding stage is 700~900℃, and the holding time is 1~3h; the temperature of the second holding stage is 1600~1850℃, and the holding time is 2~4h.

14. The method for preparing the regenerated graphite fast-filling material according to claim 13, wherein: The second insulation stage is carried out under negative pressure.

15. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: In step (2), the carbon source includes at least one of asphalt and resin.

16. The method for preparing the regenerated graphite fast-charging material according to claim 1, wherein: The amount of carbon source added is 1-10% of the weight of the heat-treated material.

17. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: The carbonization temperature is 1000~1400℃.

18. The method for preparing the regenerated graphite fast-charging material according to claim 1, wherein: The holding time at the carbonization temperature is 1 to 6 hours.

19. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: The median particle size of the carbon coating material is controlled to be 8~15μm.

20. The method for preparing the regenerated graphite fast-filling material according to claim 19, wherein: The median particle size of the carbon coating material is controlled to be 9.5-13.5 μm.

21. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: In step (2), the polymer resin is at least one of epoxy water-based resin, polyurethane resin, water-soluble phenolic resin or water-soluble polyester resin.

22. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: In the R3 to R6 of Formula 3, at least one substituent is a phosphate group or a phosphoester group, or a phosphonic acid complex.

23. The method for preparing the regenerated graphite fast-filling material according to claim 22, wherein: The formula 3 is at least one of the compounds of the following structures: Formula 3-A Formula 3-B Formula 3-C In formula 3-A to formula 3-C, the R 11 、R 12 、R 13 Alone is an alkyl group.

24. The method for preparing the regenerated graphite fast-filling material according to claim 23, wherein: The R 11 、R 12 Alone for C5~ 10 The alkyl group, the R 13 It is a C1~C5 alkyl group.

25. The method for preparing the regenerated graphite fast-filling material according to claim 23, wherein: The formula 3 comprises at least one of formula 3-A-1, formula 3-B-1, and formula 3-C-1; Formula 3-A-1 Formula 3-B-1 Formula 3-C-1.

26. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: In the formula 4, R7 to R 10 1 to 3 of them are F, and the others are H, C1 to C6 alkyl or phenyl.

27. The method for preparing the regenerated graphite fast-filling material according to claim 1, wherein: In step (2), the weight ratio of the carbon coating material and the polymer resin in the composite modifier, formula 2, formula 3 and formula 4 is 100:5~8:0.01~0.5:0.005~0.05:0.02~0.

1.

28. A regenerated graphite fast-charging material prepared by the preparation method according to any one of claims 1 to 27.

29. An application of a regenerated graphite fast-filling material prepared by the preparation method according to any one of claims 1 to 27, characterized in that: It is used as negative electrode active material to prepare secondary batteries.

30. A secondary battery, characterized in that: A regenerated graphite fast-charging material prepared by the preparation method according to any one of claims 1 to 27.

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