Physical recovery method of negative electrode material in waste pole piece

Abstract

The invention relates to the technical field of waste battery treatment, and particularly discloses a physical recovery method of a negative electrode material in a waste pole piece, and the method comprises the following steps: S1, heating pretreatment; s2, tearing the whole pole piece in a coarse crushing manner to preliminarily separate negative electrode powder, and then separating the negative electrode powder and copper foil powder in a fine crushing manner; s3, sorting: respectively collecting powder and copper foil; s4, adjusting particle size distribution of the particles in a processing mode, and repairing surface defects of the particles; and S5, performing micro-pressure calcination to realize Cu doping of the residual trace copper foil in the negative electrode material. A physical method is adopted for processing and treatment in the whole process, the recovery rate of the negative electrode material and the copper foil is larger than 98%, the content of doped copper accounts for 0.2%-0.5% of the mass of the negative electrode material, residual trace copper doping is achieved, the conductivity of the final negative electrode material can be improved by 22% or above, the first coulombic efficiency is higher than 92%, the recovery process is energy-saving, environment-friendly and convenient to operate, and the method is suitable for industrial production. And the method is suitable for recycling and processing most of the negative pole pieces of the CMC system.

Description

Technical Field

[0001] This invention relates to the field of waste battery processing technology, specifically a physical recycling method for negative electrode materials in waste electrode sheets. Background Technology

[0002] With the rapid development of the new energy industry, the market demand for power batteries and energy storage batteries has surged, leading to a large number of retired or discarded battery electrodes facing recycling and disposal issues. Existing technologies mostly employ wet recycling processes, but these require the use of large amounts of acid and alkali, causing pollution to the environment and atmosphere. Furthermore, the treatment of wastewater and dust generated by wet recycling significantly increases costs and inevitably causes some environmental pollution. Moreover, it does not utilize copper that has not been fully recycled.

[0003] Therefore, it is necessary to develop an environmentally friendly physical recycling method for anode materials. Summary of the Invention

[0004] The purpose of this invention is to provide a physical recycling method for negative electrode materials in waste electrode sheets. The entire process is carried out using physical methods, and the recovery rate of both negative electrode materials and copper foil is greater than 98%. The copper doping content is 0.2%-0.5% of the mass of the negative electrode material, achieving residual trace copper doping. This improves the conductivity of the final negative electrode material by 22% or more, and the initial coulombic efficiency is also higher than 92%. The recycling process is energy-saving, environmentally friendly, and easy to operate, and is applicable to the recycling and processing of negative electrode sheets in most CMC systems.

[0005] To address the aforementioned technical problems, this invention provides a physical method for recycling negative electrode materials from waste electrode sheets, the method comprising the following steps: S1. Pre-treat the collected waste electrode sheets by heating; S2. The waste electrode sheet that has undergone heat treatment is first torn apart by coarse crushing to initially separate the negative electrode powder, and then the negative electrode powder and copper foil powder are separated by fine crushing. S3. The mixture of the above negative electrode powder and copper foil powder is sorted and the powder and copper foil are collected separately. S4. The collected powder is processed to adjust the particle size distribution and repair particle surface defects. S5. The processed powder is subjected to micro-pressure calcination to achieve Cu doping of the residual trace copper foil in the negative electrode material.

[0006] Preferably, the waste electrode sheet in S1 is a waste electrode sheet generated before battery electrolyte injection, and the heating pretreatment temperature is 400-600℃.

[0007] Preferably, the coarse crushing method in S2 is one or both of cutting and hammering, and the coarse crushing is carried out until no large area of ​​copper foil is visible to the naked eye.

[0008] Preferably, the fine crushing method in S2 is one or more of air jet mill, rod mill, and mechanical pulverizer.

[0009] Preferably, the sorting method in S3 is one or more of the following: air separator, electrostatic separator, and ultrasonic vibrating screen.

[0010] Preferably, the processing method in S4 is one or more of high-energy ball milling, crushing, and shaping.

[0011] Preferably, the high-energy ball milling in S4 is performed using a wet or dry method, with a ball-to-material ratio of (1-4):1.

[0012] Preferably, the ball milling medium used in the wet process in S4 is one of pure water, ethanol, or ethyl acetate.

[0013] Preferably, in step S4, the particle size distribution is adjusted to an average particle size D50 = 10-20 μm.

[0014] Preferably, in step S5, the calcination temperature is 800-1100℃, an inert gas is used for protection, the pressure is 0.01-0.05MPa, the calcination time is 10-12h, and the copper doping content is 0.2%-0.5% of the mass of the negative electrode material.

[0015] The beneficial effects of this invention are: 1. This invention uses physical methods for processing and treatment throughout the entire process. The recovery rate of both negative electrode material and copper foil is greater than 98%. The copper doping content is 0.2%-0.5% of the mass of the negative electrode material, achieving residual trace copper doping, which improves the conductivity by 22% or more. The initial coulombic efficiency is also higher than 92%. The recycling process is energy-saving, environmentally friendly, and easy to operate, and is suitable for the recycling and processing of negative electrode sheets in most CMC systems. 2. The negative electrode material obtained by this invention has a uniform particle size distribution and good electrochemical performance, and can be directly reused. The calcination method used in this invention can better embed copper. Combined with the pretreatment of heating before calcination, coarse crushing followed by fine crushing, sorting, and ball milling, the recovery rate of copper and negative electrode material is improved. Furthermore, the particle size distribution is adjusted by ball milling, which is conducive to uniform mixing between particles and improves the copper doping effect. In addition, the use of micro-positive pressure for calcination can provide some pressure into the material without affecting the microcrystalline structure of the material, thereby better realizing Cu doping and improving the conductivity of the recovered negative electrode material. 3. The Cu in the copper doping of this invention comes from the residual trace amount of copper foil that could not be fully recovered after copper foil recycling (the doping copper content is 0.2%-0.5% of the mass of the negative electrode material). There is no need to introduce other copper sources. This invention can not only ensure the recovery rate of copper foil and negative electrode material, but also ensure that the Cu doping content maximizes the conductivity and rate performance of the negative electrode material. Attached Figure Description

[0016] To more clearly illustrate the technical solution of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the physical recycling method for negative electrode materials in the waste electrode sheet of the present invention. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] like Figure 1 As shown, a physical recycling method for negative electrode material in waste electrode sheets includes the following steps: S1. The collected waste electrode sheets are subjected to heat pretreatment, wherein the waste electrode sheets are waste electrode sheets generated before battery electrolyte injection, and the heat pretreatment temperature is 400-600℃. S2. The waste electrode sheet that has undergone heat treatment is first torn apart by coarse crushing to initially separate the negative electrode powder, and then the negative electrode powder and copper foil powder are separated by fine crushing. The coarse crushing method is one or two of cutting and hammer crushing, and the coarse crushing is until no large areas of copper foil are visible to the naked eye; the fine crushing method is one or more of air jet mill, rod mill, and mechanical pulverizer. S3. The mixture of the above negative electrode powder and copper foil powder is sorted and the powder and copper foil are collected separately. The sorting method is one or more of the following: air separator, electrostatic separator, and ultrasonic vibrating screen; S4. The collected powder is processed to adjust the particle size distribution and repair particle surface defects. The processing method includes one or more of high-energy ball milling, pulverization, and shaping; the high-energy ball milling adopts wet or dry methods, and the ball-to-material ratio is (1-4):1; if wet ball milling is adopted, the ball milling medium used is one of pure water, ethanol, and ethyl acetate. Adjust the particle size distribution to an average particle size D50 = 10-20 μm; S5. The processed powder is subjected to micro-pressure calcination to achieve Cu doping of the residual trace copper foil in the negative electrode material. The calcination temperature is 800-1100℃, inert gas is used for protection, the pressure is 0.01-0.05MPa, the calcination time is 10-12h, and the copper doping content is 0.2%-0.5% of the mass of the negative electrode material.

[0020] Specifically, the present invention provides three embodiments and two comparative examples based on the above method, as follows: Example

[0021] A physical method for recycling negative electrode material from waste electrode sheets, the method comprising the following steps: S1. The collected waste electrode sheets are pretreated by heating at 400℃, under nitrogen protection, and kept at that temperature for 30 minutes. S2. The waste electrode sheets that have undergone heat treatment are first coarsely crushed by a hammer crusher until no large-area fragments are visible to the naked eye (<3cm×3cm), and then finely crushed by an air jet mill. S3. Use an air classifier to separate copper foil and negative electrode material at a wind speed of 8 m / s. The negative electrode material passes through a 120-mesh ultrasonic vibrating screen and the undersize material is collected. S4. Wet high-energy ball milling is used for processing, with a ball-to-material ratio of 2:1, ethanol as the milling medium, and a milling time of 15 hours. S5. The processed powder is calcined at a temperature of 800℃, with argon protection, a pressure of 0.02MPa, and a time of 10 hours.

[0022] Through the above steps, the final recycled negative electrode material A is obtained, and its physical parameters and electrochemical performance are tested, as shown in Table 1. Example

[0023] A physical method for recycling negative electrode material from waste electrode sheets, the method comprising the following steps: S1. The collected waste electrode sheets are pretreated by heating at 550℃ under nitrogen protection for 20 minutes. S2. The waste electrode sheets that have undergone heat treatment are first coarsely crushed and cut into irregular fragments of about 3 cm × 3 cm using a cutting machine. Then, they are finely crushed using a pin mill at a speed of 3000 RPM. S3. Electrostatic separation is adopted with a voltage of 15 kV. The screened powder is then processed by a 60-mesh vibrating screen. S4. Dry mechanical shaping is adopted, with the main unit frequency at 15Hz and the grading main unit at 25Hz. S5. The shaped powder is calcined at a temperature of 1000℃, under nitrogen protection at a pressure of 0.05 MPa for 12 hours.

[0024] Through the above steps, the final recycled negative electrode material B is obtained, and its physical parameters and electrochemical performance are tested, as shown in Table 1. Example

[0025] A physical method for recycling negative electrode material from waste electrode sheets, the method comprising the following steps: S1. The collected waste electrode sheets are pretreated by heating at a temperature of 600℃, under nitrogen protection, and kept at that temperature for 15 minutes. S2. The heat-treated waste electrode sheets are first coarsely crushed, specifically by a combination of cutting and hammer crushing, until no large-area fragments are visible to the naked eye (<3cm×3cm); then finely crushed using a mechanical pulverizer with a pulverizer frequency of 25Hz. S3. Air classifier is used for separation, with an air speed of 10 m / s, combined with electrostatic separation, and the working voltage is 20 kV. S4. Processing is carried out by wet ball milling with ethyl acetate, with a ball-to-material ratio of 4:1 and a time of 20 hours. S5. The processed powder is calcined at a temperature of 1100℃, with argon protection, a pressure of 0.01 MPa, and a time of 12 hours.

[0026] Through the above steps, the final recycled negative electrode material C is obtained, and its physical parameters and electrochemical performance are tested, as shown in Table 1.

[0027] The difference from Example 1 is that the pretreatment temperature in S1 is 700°C, while the other steps are the same as in Example 1.

[0028] Through the above steps, the final recycled negative electrode material D is obtained, and its physical parameters and electrochemical performance are tested, as shown in Table 1.

[0029] The difference from Example 2 is that the calcination in step S5 is omitted, while the remaining steps are the same as in Example 2.

[0030] Through the above steps, the final recycled negative electrode material E is obtained, and its physical parameters and electrochemical performance are tested, as shown in Table 1 below. Table 1 Projects / Case Studies Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Copper foil recovery rate 98.5% 98.8% 99.1% 82.3% 94.7% Anode material recovery rate 98.2% 98.6% 98.9% 85.4% 93.2% Increased conductivity 22% 35% 42% 9% 15% First Coulomb Efficiency 92.5% 94.1% 93.8% 83.7% 91.9% Cyclic performance Maintain 93% after 100 cycles at 0.5C. 1C cycle 200 times, maintain 90% Maintain 85% after 50 cycles of 2C. 0.5C, 100 cycles, maintain 75% 1C cycle 200 times, maintaining 78% According to Examples 1-3 of the physical recycling method of negative electrode material in waste electrode sheets of the present invention, the recovery rate of negative electrode material and copper foil is greater than 98%, and the copper doping content in Examples 1-3 is 0.2%-0.5% of the mass of negative electrode material. The present invention does not require the introduction of other Cu sources, achieves the maximum utilization rate of recycled resources, and the conductivity is improved by 22% or more, and the initial coulombic efficiency is also higher than 92%. Furthermore, with the increase and effective combination of sorting methods, the recovery rate of negative electrode materials and copper foil will be improved. For example, in Example 3, the sorting method of air classification combined with electrostatic separation was used, and the recovery rate of negative electrode materials reached 98.9%, and the recovery rate of copper foil reached 99.1%. Specifically, air classification utilizes density difference separation, combined with electrostatic separation of copper after crushing, which can improve the overall copper recovery rate. In addition, the copper doping in Example 3 is more thorough, which increases the conductivity between graphite layers, and the conductivity is improved by 42%. As can be seen from the comparison between Example 1 and Comparative Example 1, it is important to control the heat treatment temperature. If the heat treatment temperature is too high, Cu will be oxidized, resulting in a decrease in Cu recovery rate and conductivity. Experiments have shown that the pretreatment temperature is controlled in the range of 400-600℃. Example 2 uses dry forming, and the initial coulombic efficiency of the final recycled negative electrode material B can reach 94.1%, with good cycle performance, maintaining 90% after 200 cycles at 1C. Comparing Examples 1-3 and Comparative Example 2, the conductivity increase without calcination is only 15%, and the initial coulombic efficiency is less than 92%. This demonstrates that the final calcination process in this invention is a crucial step in achieving copper doping. Calcination in this invention allows for better copper embedding. Combined with pre-treatment by heating, coarse crushing followed by fine crushing, sorting, and ball milling, the recovery rate of copper and anode materials is improved. Furthermore, ball milling adjusts the particle size distribution, facilitating uniform mixing and enhancing the copper doping effect. The use of micro-positive pressure during calcination provides pressure into the material without affecting its microcrystalline structure, better achieving Cu doping and improving the conductivity of the recovered anode material. In the calcination process of this invention, the Cu in the copper doping comes from the residual trace amount of copper foil that could not be fully recovered after copper foil recycling (the doping copper content is 0.2%-0.5% of the mass of the negative electrode material). There is no need to introduce other copper sources. This invention can not only ensure the recovery rate of copper foil and negative electrode material, but also ensure that the Cu doping content maximizes the improvement of the electrical performance of the negative electrode material.

[0031] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, any equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. A physical method for recycling negative electrode material from waste electrode sheets, characterized in that, The method includes the following steps: S1. Pre-treat the collected waste electrode sheets by heating; S2. The waste electrode sheet that has undergone heat treatment is first torn apart by coarse crushing to initially separate the negative electrode powder, and then the negative electrode powder and copper foil powder are separated by fine crushing. S3. The mixture of the above negative electrode powder and copper foil powder is sorted and the powder and copper foil are collected separately. S4. The collected powder is processed to adjust the particle size distribution and repair particle surface defects. S5. The processed powder is subjected to micro-pressure calcination to achieve Cu doping of the residual trace copper foil in the negative electrode material.

2. The physical recycling method for negative electrode material in waste electrode sheets according to claim 1, characterized in that, The waste electrode sheet in S1 is the waste electrode sheet generated before the battery is injected with electrolyte, and the heating pretreatment temperature is 400-600℃.

3. The physical recycling method for negative electrode material in waste electrode sheets according to claim 1, characterized in that, The coarse crushing method in S2 is one or both of cutting and hammer crushing.

4. The physical recycling method for negative electrode material in waste electrode sheets according to claim 1, characterized in that, The fine crushing method in S2 is one or more of air jet mill, rod mill, and mechanical crusher.

5. The physical recycling method for negative electrode material in waste electrode sheets according to claim 1, characterized in that, The sorting method in S3 is one or more of the following: air separator, electrostatic separator, and ultrasonic vibrating screen.

6. The physical recycling method for negative electrode material in waste electrode sheets according to claim 1, characterized in that, The processing method in S4 is one or more of high-energy ball milling, crushing, and shaping.

7. A physical recycling method for negative electrode material in waste electrode sheets according to claim 6, characterized in that, The high-energy ball mill in S4 is performed using either a wet or dry method, with a ball-to-material ratio of (1-4):

1.

8. A physical recycling method for negative electrode material in waste electrode sheets according to claim 7, characterized in that, The ball milling media used in the wet process in S4 is one of pure water, ethanol, or ethyl acetate.

9. A physical recycling method for negative electrode material in waste electrode sheets according to claim 1, characterized in that, In step S4, the particle size distribution is adjusted to an average particle size D50 = 10-20 μm.

10. A physical recycling method for negative electrode material in waste electrode sheets according to claim 1, characterized in that, The calcination temperature in S5 is 800-1100℃, protected by inert gas, with a pressure of 0.01-0.05MPa, a calcination time of 10-12h, and the copper doping content is 0.2%-0.5% of the mass of the negative electrode material.

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