A method for efficiently repairing structural defects of waste graphite based on joule heat flash evaporation technology

Abstract

The application discloses a method for efficiently repairing structural defects of waste graphite based on a Joule heat flash evaporation technology, which realizes millisecond-level instantaneous carbonization of waste resin and directional deposition of the waste resin on the surface of graphite layers and the defect area between the layers by selection of multi-source waste resin and combination of Joule heat flash evaporation pyrolysis and post-processing, can target compensation and repair of surface / edge defects of graphite layers, in-plane lattice defects of layers and interlayer structural defects, and thus can accurately and significantly improve the graphitization degree and electrochemical performance of regenerated graphite, realize high-value-added reuse of waste graphite, and has the advantages of energy saving, environmental protection, high efficiency, greenness and scalability.

Description

Technical Field

[0001] This invention relates to the field of waste lithium-ion battery recycling and waste resin resource utilization technology, specifically to a method for efficiently repairing structural defects in waste graphite based on Joule thermal flash evaporation technology. Background Technology

[0002] With the rapid development of new energy vehicles and energy storage industries, the number of waste lithium-ion batteries has surged. Among them, waste graphite anodes are prone to delamination, structural degradation, and surface impurity accumulation due to long-term cycling, making direct reuse difficult. Currently, the main methods for treating waste graphite anodes include physical sorting, thermal treatment repair, and chemical dissolution. Physical methods rely on ultrasonic, mechanical, or airflow sorting to remove binders, but cannot effectively restore the graphite lattice structure; traditional thermal treatment can decompose impurities, but the heating rate is slow, energy consumption is high, and it is easy to cause excessive graphite ablation; chemical methods can remove coatings, but require the use of strong acids and alkalis, which have problems such as strong corrosiveness, high pollution risk, and high cost.

[0003] Using waste resin as a carbon source for the remediation of waste graphite offers significant advantages in "treating waste with waste." From the raw material perspective, the extensive use of thermosetting resins in aerospace, electronics, and composite materials industries has led to a continuous increase in their waste volume. Existing waste resin recycling methods, such as energy recovery, physical reuse, and chemical depolymerization, generally suffer from energy waste, low added value of recycled materials, or difficulties in product separation. From the application perspective, while resin-based carbon sources offer advantages such as high carbon yield and tunable structure, conventional resin pyrolysis is limited by low heat transfer efficiency and uneven carbonization, making it difficult to form a uniform carbon layer to fill graphite defects in a short time. Therefore, using waste resin as a carbon source for graphite remediation, achieving the synergistic high-value utilization of waste resin and waste graphite anodes, is of great significance but still lacks efficient technological support.

[0004] Against this backdrop, Joule heating flash evaporation technology, with its advantages of extremely high heating rate, high energy utilization efficiency, and short reaction time, has shown potential in the preparation of rapid carbon materials, providing a new approach to solving the aforementioned process bottlenecks. CN121493966A discloses a method for recovering high-purity graphite from black powder leaching residue. This method includes the following steps: S1, removing impurity elements from graphite by flash Joule heating of the black powder leaching residue; S2, placing the impurity-removed black powder leaching residue into a ball mill, adding liquid phenolic resin, mixing thoroughly, and ball milling; S3, placing the ball-milled mixture into a flash Joule heating device to carbonize the phenolic resin into graphite, obtaining regenerated graphite. In step S1, the temperature of the flash Joule heating is 2700-2900 K. At this temperature, most impurities can be completely removed, and the impurity content in the graphite meets the requirements for battery-grade graphite. Simultaneously, the structure and properties of the graphite are improved to some extent, but some lattice defects still exist. By placing the impurity-removed black powder leaching residue into a ball mill and adding liquid phenolic resin, followed by thorough mixing and ball milling, subsequent repair of the graphite structure is facilitated, ensuring the uniformity of the material reaction. Step S3, flash Joule heating at 2500-3000K, carbonizes the phenolic resin into graphite. The resulting disordered carbon can fill particle cracks and internal lattice defects in the waste graphite, establishing a conductive network between graphite particles and forming a dense carbon layer on the graphite surface. This step also induces graphite structural transformation. The recycled graphite obtained by this method has a capacity similar to commercial graphite and good cycle stability. However, this method involves two Joule heat flash evaporation processes at high temperatures, and the flash evaporation time and heating rate are unclear. Currently, there is still a lack of an effective method for the precise repair of structural defects in the negative electrode of waste graphite by synergistically combining multi-source resins with Joule heat flash evaporation. How to achieve instantaneous pyrolysis of waste resin, rapid nucleation and carbonization, and precise compensation for structural defects in waste graphite, while simultaneously achieving low energy consumption, green production, and improved material performance, remains a key issue that needs to be addressed by existing technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a method for efficiently repairing structural defects in waste graphite based on Joule thermal flash evaporation technology, which solves the problems of cumbersome process, inability to accurately compensate for structural defects in waste graphite, high energy consumption and low efficiency in the existing technology.

[0006] This invention is achieved through the following technical solutions: A method for efficiently repairing structural defects in waste graphite based on Joule thermal flash evaporation technology, the method comprising the following steps: S1. Waste graphite pretreatment and multi-source resin screening: Waste lithium battery anode materials are demetallic impurities by solvent removal, hot air drying and screening to obtain pretreated waste graphite; different types of multi-source waste resins are selected as carbon sources according to the defect type of waste graphite. The waste resins are screened according to carbon yield, thermal decomposition characteristic peak temperature, aromatization tendency and chemical composition of decomposition products to match the structural defect type of waste graphite and achieve targeted repair. S2. Construction of resin / waste graphite composite material: The selected waste resin and pretreated waste graphite are mixed in a mass ratio of 1:5 to 5:1, preferably 1:1. The resin is fully and uniformly contacted with cracks, broken edges and surface pits on the graphite flakes by high-speed mechanical ball milling and other methods to obtain resin-graphite composite material. S3. Joule flash evaporation repair: The resin-graphite composite material obtained in step S2 is placed in a Joule flash reactor. An electric current is applied under an inert atmosphere, and the reaction temperature is controlled at 1300℃~2200℃, preferably 1600℃~1800℃, with a heating rate of 10°C / min. 3 ~10 5 The resin is pyrolyzed instantaneously at ℃ / s for 10 ms to 5 s, and a highly aromatic nano-carbon layer is rapidly formed. This layer is deposited on the surface of the graphite sheets and penetrates into the interlayer and defect areas, thereby achieving sheet defect repair, dislocation rearrangement and local crystal structure reconstruction. S4. Cooling and post-treatment: After the reaction is completed, the material is naturally cooled, the recycled graphite material is collected, and it is then compacted, sieved, and annealed in an inert atmosphere at 600℃~1200℃ to further stabilize the structure of the new carbon layer, eliminate local amorphous carbon, and improve the degree of graphitization, so that the recycled graphite can reach or exceed the level of commercial graphite in terms of rate performance, cycle life and first coulombic efficiency.

[0007] Defects in waste graphite are classified into three main categories: surface / edge defects of graphite sheets, intra-sheet lattice defects, and interlayer structural defects. Among them, surface / edge defects of graphite sheets include edge breakage, surface cracks, local sheet peeling, and surface pitting; intra-sheet lattice defects include vacancy defects and disordered carbon regions; and interlayer structural defects include increased interlayer spacing and disordered interlayer stacking.

[0008] Preferably, in step S1, the waste resin types include: linear molecular chain structure resins, such as polyethylene (PE); resins with aromatic backbone structures, such as polystyrene (PS); and thermosetting resins with three-dimensional cross-linked structures, such as epoxy resin (EP) and phenolic resin (PF). Different types of waste resins can retain their original molecular structure characteristics to a certain extent during pyrolysis and carbonization, forming carbonaceous intermediates or pyrolytic carbon with different configurations, densities, and degrees of aromaticity. This allows them to match different types of graphite defects and achieve differentiated compensation and repair. Among them, linear molecular chain resins such as PE, which form carbonaceous deposits or carbon-filling phases during pyrolysis and carbonization, are preferentially suitable for compensating and repairing surface / edge defects of graphite sheets, including edge damage, surface cracks, and local sheet peeling areas; resins with aromatic main chains or aromatic side groups, such as PS, are more likely to form highly aromatic carbonaceous sheets or conjugated carbon structures after pyrolysis, and are preferentially suitable for compensating, passivating, and regulating the ordering of lattice defects (including vacancy defects and disordered carbon regions) within graphite sheets, and can also be used for regulating and repairing some interlayer structural defects of graphite, such as disordered interlayer stacking; resins with three-dimensional cross-linked structures, such as EP, are more likely to form cross-linked carbon skeletons with certain spatial support and connection functions after pyrolysis, and are preferentially suitable for filling, bridging, and connecting repairs of surface / edge defects of graphite sheets, such as surface pits and large edge damage areas; PF has a high carbonization rate after pyrolysis and is easy to form a relatively dense carbon layer, and is preferentially suitable for densifying repairs of surface / edge defects of graphite sheets, such as edge damage and surface cracks.

[0009] Preferably, in step S2, the waste resin and pretreated waste graphite are mixed by high-speed mechanical ball milling for 0.5-6 hours to ensure that the resin is evenly distributed on the graphite surface and in the cracks, thereby improving the carbon replenishment efficiency.

[0010] Preferably, the heating rate of the Joule flash reactor in step S3 is 10. 4 ℃ / s~10 5 Temperature (℃ / s) is used to ensure that the resin undergoes complete pyrolysis at instantaneous high temperature, avoiding excessive carbonization or large molecular residues.

[0011] Preferably, when the reaction temperature in step S3 is controlled at 1600℃~1800℃, the optimal layer repair effect can be obtained, and the interlayer spacing of the resulting recycled graphite is reduced, the defect density is reduced, and the crystal integrity is significantly improved.

[0012] The reaction time in step S3 is 10 ms to 5 s, which not only further reduces the energy consumption of heat treatment, but also ensures uniform deposition of the carbon supplement layer and reduces the ablation of graphite sheets.

[0013] Preferably, the post-treatment annealing temperature in step S4 is 800℃~1200℃, which is used to eliminate the amorphous carbon deposited by Joule thermal deposition and improve the stability of the overall graphite structure.

[0014] Compared with the prior art, the present invention has the following advantages: 1) Rapid, efficient and precise repair of graphite structural defects: By selecting multi-source waste resin and combining Joule heat flash pyrolysis with post-treatment, waste resin is carbonized instantaneously in milliseconds and directionally deposited in the defect area of ​​waste graphite. It can target and compensate for defects on the surface / edge of graphite sheets, intra-sheet lattice defects and interlayer structural defects. In particular, it can effectively repair typical defects such as edge damage, disordered carbon regions and disordered interlayer stacking, thereby promoting carbon replenishment at defect sites, carbon layer reconstruction and restoration of ordered stacking of graphite microcrystals, and accurately and significantly improving the graphitization degree and electrochemical performance of recycled graphite. 2) Energy saving and environmental protection, reducing processing costs: Utilizing the ultra-high heating rate (10) of the Joule thermal flash reactor. 3 ~10 5 The Joule flash reactor temperature is controlled at a relatively low temperature of 1300℃~2200℃ to achieve instantaneous heat treatment, avoiding high energy consumption. At the same time, the waste resin is used as a carbon source to achieve resource synergy, which has good economic and environmental benefits. 3) Flexible and controllable material regulation capabilities: By screening resins with different molecular structures (such as linear, cross-linked, or aromatic ring structures), adjusting the resin doping ratio, and controlling the reaction temperature and heating rate of the Joule flash reactor (10... 3 ~10 5 (℃ / s) to achieve fine control of the structure of recycled graphite, optimize the carbon layer deposition morphology and graphitization degree, and improve the controllability of the overall material performance.

[0015] In summary, this invention achieves instantaneous carbonization and directional deposition of waste resin in defective areas of waste graphite within milliseconds by selecting multi-source waste resin and combining Joule thermal flash pyrolysis with post-treatment. It can target and compensate for defects on the surface / edge of graphite sheets, lattice defects within sheets, and interlayer structural defects. It is particularly suitable for the effective repair of defects such as edge damage of graphite sheets, disordered carbon regions within sheets, and disordered interlayer stacking. This significantly improves the graphitization degree, structural integrity, and electrochemical performance of recycled graphite, realizing high-value reuse of waste graphite, and also has the advantages of energy saving, environmental protection, high efficiency, greenness, and scalability. Attached Figure Description

[0016] Figure 1These are graphite characterization images of waste graphite before and after regeneration in Examples 1-3. Specifically, a and b are TEM images of waste graphite in Example 1 before regeneration, showing disordered carbon regions and disordered interlayer stacking; c is a TEM image of regenerated graphite in Example 1 after annealing, showing repair of disordered carbon regions and disordered interlayer stacking, with a highly ordered lattice in the regenerated graphite; d and e are SEM images of waste graphite in Example 2 before regeneration, showing surface pits and large edge damage areas; f is a SEM image of regenerated graphite in Example 2 after annealing, showing a smooth surface and repair of surface pits and large edge damage areas; g and h are SEM images of waste graphite in Example 3 before regeneration, showing edge damage and surface cracks; i is a TEM image of regenerated graphite in Example 3 after annealing, showing repair of edge damage and surface cracks.

[0017] Figure 2 The images are XRD and Raman spectra of the raw material (pretreated waste graphite), the recycled graphite obtained without resin in Comparative Example 1, and the recycled graphite obtained with PS resin in Example 1; where (a) is the XRD pattern and (b) is the Raman spectrum.

[0018] Figure 3 These are the rate performance graphs of regenerated graphite after repairing structural defects using different resins in Examples 1-3; where RG-PS represents the rate performance of regenerated graphite obtained in Example 1, RG-EP represents the rate performance of regenerated graphite obtained in Example 2, and RG-PF represents the rate performance of regenerated graphite obtained in Example 3. Detailed Implementation

[0019] The following is a further description of the invention, but not a limitation thereof.

[0020] Example 1: A method for repairing structural defects in graphite anodes of waste lithium batteries using multi-source resin Joule thermal flash evaporation. Includes the following steps: S1. Pretreatment of waste graphite and screening of multi-source resins: Waste lithium battery anode materials were subjected to solvent removal of metal impurities, hot air drying, and screening to obtain pretreated waste graphite [Reference: Z. Zhang, R. Lu, T. Li, Z. Liu, H. Nie, R. Wang, et al. Green and sustainable recycling of spent lithiumbatteries: synergistic leaching of SLFP and SLMO for valuable metal extraction and environmental benefits. Green Chemistry. 27 (2025), 4688-705]; its SEM image is shown below. Figure 1 In sections a and b, the pretreated waste graphite has intra-layer lattice defects (disordered carbon regions) and interlayer structural defects (interlayer stacking disorder). Waste polystyrene powder is selected according to the defect type of the waste graphite to repair the disordered carbon regions and interlayer stacking disorder structural defects in the waste graphite.

[0021] S2. Mix 1 g of pretreated waste graphite with 1 g of waste polystyrene powder at a mass ratio of 1:1, and then ball mill at high speed for 5 h to uniformly load the resin onto the surface of the graphite flakes to form a composite material.

[0022] S3. Place the composite material obtained in step S2 in a Joule flash reactor, apply an electric current under argon protection to instantly raise the sample temperature to 1800℃, with a heating rate of approximately 10. 4 At ℃ / s, with a reaction time of 1 s, the resin undergoes instantaneous pyrolysis, carbonization, and deposition.

[0023] S4. After natural cooling, the recycled graphite was collected and subjected to compaction, sieving, and inert atmosphere annealing (800℃, 1h) to further stabilize the carbon layer structure. The obtained recycled graphite was characterized, and its SEM image is shown below. Figure 1 For its XRD and Raman spectra, see [link to relevant documentation]. Figure 2 The electrochemical performance of the obtained recycled graphite was tested, mainly focusing on its rate performance at currents of 0.1 C–2 C and its long-term charge-discharge cycle stability at 0.2 C. Electrochemical tests showed that the specific capacity of the recycled graphite at 0.1 C was 410 mAh g⁻¹. -1 Furthermore, it exhibits good cyclic stability, retaining 93% of its specific capacity after 100 cycles at 0.2 C. Detailed results are shown in Table 1 and... Figure 3 .

[0024] Example 2: S1. Referring to Example 1, the difference is that epoxy resin is selected mainly for repairing surface pits and larger edge damage areas.

[0025] S2. Mix 1 g of pretreated waste graphite with 2 g of epoxy resin powder at a mass ratio of 1:2, and mix by high-speed mechanical ball milling for 2 h to obtain a uniform composite material.

[0026] S3. Place the composite material in a Joule flash reactor and apply an electric current under an argon atmosphere to instantly raise the sample temperature to 1800℃ at a heating rate of approximately 10. 4 ℃ / s, reaction time 2 s.

[0027] S4. After natural cooling, the recycled graphite was collected and subjected to tapping and inert atmosphere annealing (800℃, 1 h). The electrochemical performance of the obtained recycled graphite was tested, mainly focusing on its rate performance and long-term charge-discharge cycle stability at currents of 0.1 C–2 C. Electrochemical tests showed that the specific capacity of the recycled graphite at 0.1 C was 360 mAh g⁻¹. -1 It exhibits good cyclic stability, with a specific capacity retention rate of 90% after 100 cycles at 0.2 C. Detailed results are shown in Table 1.

[0028] Example 3: S1. Referring to Example 1, the difference is that phenolic resin is selected mainly for repairing edge damage and surface cracks.

[0029] S2. Mix 1 g of pretreated waste graphite with 0.5 g of phenolic resin powder at a mass ratio of 2:1, and disperse them evenly by high-speed mechanical ball milling for 4 h to form a composite material.

[0030] S3. Place the composite material in a Joule flash reactor, apply an electric current under an inert gas atmosphere, and instantly heat the sample to 1800℃ at a heating rate of approximately 2×10⁻⁶. 4 ℃ / s, reaction time 0.8 s.

[0031] S4. After natural cooling, the regenerated graphite was collected and subjected to tapping and inert atmosphere annealing (800℃, 1 h). The electrochemical performance of the obtained regenerated graphite was tested, mainly its rate performance at 0.1 C–2 C and its long-term charge-discharge cycle stability at 0.2 C. Electrochemical tests showed that the specific capacity of the regenerated graphite at 0.1 C was 325 mAh g⁻¹. -1 It exhibits good cyclic stability, with a specific capacity retention rate of 86% after 100 cycles at 0.2 C. Detailed results are shown in Table 1.

[0032] Comparative Example 1 (blank control, no resin doping): Referring to Example 1, the differences are: in S2, no waste polystyrene powder was added; and in S3, only 1 g of waste graphite was placed in the Joule heat flash reactor. The obtained recycled graphite was characterized, and its XRD and Raman spectra are shown below. Figure 2 Due to the lack of an exogenous resin carbon source, this comparative example cannot provide targeted repair for different defect types, such as vacancy defects, interlayer defects, and edge damage. Electrochemical performance tests were conducted on the obtained recycled graphite, primarily examining its rate performance at 0.1 C–2 C currents and its long-term charge-discharge cycle stability at 0.2 C. Electrochemical tests showed that the specific capacity of the recycled graphite at 0.1 C was 273 mAh g⁻¹. -1 However, the cycle stability is poor; after 100 cycles at 0.2 C, the specific capacity retention rate is only 65%, as detailed in Table 1. A comparison of the results of Example 1 and Comparative Example 1 illustrates that without resin, simple flash heat treatment is insufficient to simultaneously repair different types of structural defects.

[0033] Comparative Example 2 (resin dosage was significantly insufficient): Referring to Example 1, the difference is that: S1, 1 g of waste graphite and 0.2 g of polystyrene (PS) powder are mixed at a mass ratio of 5:1 and uniformly mixed by high-speed mechanical ball milling for 4 h.

[0034] The electrochemical performance of the obtained recycled graphite was tested, mainly focusing on its rate performance at currents of 0.1 C–2 C and its long-term charge-discharge cycle stability at 0.2 C. Electrochemical tests showed that the recycled graphite had a low specific capacity of 245 mAh g⁻¹ at 0.1 C. -1 Furthermore, the cycling stability was poor; after 100 cycles at 0.2 C, the specific capacity retention rate was only 70%, as detailed in Table 1. A comparison of the results from Example 1 and Comparative Example 2 shows that when the PS dosage is insufficient, the carbon replenishment and repair of vacancies and interlayer defects are inadequate.

[0035] Comparative Example 3 (Jaull heat flash reaction temperature is lower): Referring to Example 1, the difference is: S3, the composite material is placed in a Joule flash reactor, and an electric current is applied under argon protection to instantly heat the sample to 1200°C at a heating rate of approximately 10. 4 ℃ / s, reaction time 1 s.

[0036] The electrochemical performance of the obtained recycled graphite was tested, mainly focusing on its rate performance at currents of 0.1 C–2 C and its long-term charge-discharge cycle stability at 0.2 C. Electrochemical tests showed that the specific capacity of the recycled graphite at 0.1 C was 350 mAh g⁻¹. -1 However, its cycling stability is poor. After 100 cycles at 0.2 C, the specific capacity retention rate is only 68%. Detailed results are shown in Table 1.

[0037] Comparative Example 4 (without post-annealing treatment): Referring to Example 1, the difference lies in S4: after natural cooling, the recycled graphite is collected directly without annealing; only simple sieving is performed. The obtained recycled graphite is then subjected to electrochemical performance testing, primarily focusing on its rate performance at 0.1 C–2 C currents and its long-term charge-discharge cycle stability at 0.2 C. Electrochemical tests show that the specific capacity of the recycled graphite at 0.1 C is 342 mAh g⁻¹. -1 After 100 cycles at 0.2 C, the specific capacity retention rate was 81%, as detailed in Table 1.

[0038] The results of Example 1 and Comparative Example 4 show that, compared with natural cooling combined with annealing post-treatment, the lack of post-treatment is not conducive to stress release of the newly formed carbon layer and removal of amorphous carbon, thereby weakening the stable repair effect on interlayer defects and disordered carbon regions.

[0039] Comparative Example 5 (Joule flash reaction at a higher temperature): Referring to Example 1, the difference lies in S3: the composite material is placed in a Joule-thermal flash reactor, and an electric current is applied under argon protection to instantly heat the sample to 2300℃. The electrochemical performance of the obtained recycled graphite is tested, mainly its rate performance at 0.1 C–2 C and its long-term charge-discharge cycle stability at 0.2 C. Electrochemical tests show that the specific capacity of the recycled graphite is 338 mAh g⁻¹ at 0.1 C, and the specific capacity retention rate is 76% after 100 cycles at 0.2 C. Detailed results are shown in Table 1.

[0040] Table 1 Electrochemical performance test results for different cases

[0041] The comparison between the results of Example 1 and Comparative Example 3 shows that a Joule flash temperature that is too low is not conducive to the structural repair and electrochemical performance improvement of regenerated graphite.

[0042] The comparison between the results of Example 1 and Comparative Example 5 shows that excessively high Joule flash evaporation temperature reduces the effective deposition and filling efficiency of the repair carbon source on the defect sites of waste graphite, resulting in insufficient defect compensation or uneven repair, which in turn reduces the structural repair effect and electrochemical performance of the recycled graphite.

Claims

1. A method for efficiently repairing structural defects in waste graphite based on Joule thermal flash evaporation technology, characterized in that, The method includes the following steps: S1. Waste graphite pretreatment and multi-source resin screening: Waste lithium battery anode materials are demetallic impurities by solvent removal, hot air drying and screening to obtain pretreated waste graphite; different types of multi-source waste resins are selected as carbon sources according to the defect type of waste graphite. The waste resins are screened according to carbon yield, thermal decomposition characteristic peak temperature, aromatization tendency and chemical composition of decomposition products to match the structural defect type of waste graphite and achieve targeted repair. S2. Construction of resin / waste graphite composite material: The selected waste resin and pretreated waste graphite are mixed at a mass ratio of 1:5 to 5:1, and the resin-graphite composite material is obtained by high-speed mechanical ball milling. S3. Joule flash evaporation repair: The resin-graphite composite material obtained in step S2 is placed in a Joule flash reactor. An electric current is applied under an inert atmosphere, and the reaction temperature is controlled at 1300℃~2200℃ with a heating rate of 10°C / min. 3 ~10 5 The resin was pyrolyzed instantaneously at ℃ / s for 10 ms to 5 s. S4. Cooling and post-treatment: After the reaction is completed, the material is allowed to cool naturally, the recycled graphite material is collected, and it is then compacted, sieved, and annealed in an inert atmosphere at 600℃~1200℃.

2. The method according to claim 1, characterized in that, The waste resin screened in step S2 is mixed with the pretreated waste graphite at a mass ratio of 1:

1.

3. The method according to claim 1, characterized in that, The reaction temperature in step S3 is 1600℃~1800℃.

4. The method according to claim 1, characterized in that, In step S1, the waste resin type includes one of the following: linear molecular chain structure resin, resin with aromatic main chain, and thermosetting resin with three-dimensional cross-linked structure.

5. The method according to claim 4, characterized in that, Resins with linear molecular chain structures are suitable for compensating and repairing surface / edge defects of graphite sheets; resins with aromatic main chains or aromatic side groups are suitable for compensating, passivating, and regulating the ordering of lattice defects within graphite sheets, and can also be used for regulating and repairing some interlayer structural defects in graphite; resins with three-dimensional cross-linked structures are suitable for compensating and repairing surface / edge defects of graphite sheets.

6. The method according to claim 4 or 5, characterized in that, The linear molecular chain structure resin is selected from polyethylene, the aromatic main chain resin is selected from polystyrene, and the thermosetting resin with a three-dimensional cross-linked structure is selected from epoxy resin and phenolic resin.

7. The method according to claim 1, characterized in that, In step S2, the waste resin and pretreated waste graphite are mixed by high-speed mechanical ball milling for 0.5-6 hours.

8. The method according to claim 1, characterized in that, The heating rate of the Joule flash reactor in step S3 is 10 4 ℃ / s~10 5 The reaction temperature was controlled at 1600℃~1800℃, and the reaction time was 10 ms~5 s.

9. The method according to claim 1, characterized in that, In step S4, the post-processing annealing temperature is 800℃~1200℃.

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