Method for dry electrode film recycling

Abstract

The present application relates to the technical field of dry electrode film recycling, and specifically relates to a dry electrode film recycling method, which comprises the following steps: S1, freezing and drying the electrode film; S2, crushing the electrode film at 0-20 DEG C to obtain coarse material; S3, crushing part of the coarse material to obtain fine material; S4, spraying a silane coupling agent solution on the surface of the coarse material and vacuum drying; S5, uniformly mixing the coarse material, a binder and a conductive agent through a mixer and performing heat preservation treatment to obtain first mixed material; S6, uniformly mixing the fine material, an active material and an electrolyte through a mixer to obtain second mixed material; and S7, mixing the first mixed material and the second mixed material and performing fiberization treatment to obtain recyclable dry electrode film powder. The coarse material is combined with the binder to form a preliminary framework, and then the fine material is combined to enhance the interface bonding capacity between the recycled materials, reduce interface defects and effectively improve the electrochemical performance of the prepared battery.

Description

Technical Field

[0001] This invention relates to the field of dry electrode membrane recycling technology, specifically a dry electrode membrane regeneration and utilization method. Background Technology

[0002] There are two main methods for preparing electrode films: wet electrode film preparation and dry electrode film preparation. Compared to wet processes, dry processes have the following significant advantages. Dry processes do not require solvents, while wet processes often use large quantities of solvents, which are environmentally unfriendly and require recycling after use, increasing production costs. Dry processes, on the other hand, directly press electrode material powder onto a metal current collector to form the electrode, eliminating the need for solvents and making them more environmentally friendly. Furthermore, wet processes require an environment to dry the solvent, and the preparation of electrode films often requires a larger space, undoubtedly increasing production costs.

[0003] In the production process of dry electrode films, the electrode films need to be cut, which easily generates a lot of irregular scraps. These scraps can still be reused. Therefore, we propose a method for recycling scraps from the production of dry electrode films. Summary of the Invention

[0004] The purpose of this invention is to provide a dry electrode film regeneration method to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A method for regenerating and reusing dry electrode films includes the following steps: S1. Cut off the irregular part of the dry electrode film and then freeze-dry it at -100~-50℃ for 6~10h; S2. The dry electrode film treated in step S1 is pulverized once at 0~20℃ to obtain coarse material with a particle size of 50~100um; S3. A portion of the coarse material obtained in step S2 is pulverized a second time at 0~20℃ to obtain fine material with a particle size of 5~20um; S4. Spray silane coupling agent solution onto the surface of the remaining coarse material that has not undergone secondary crushing, stir the coarse material, and vacuum dry the coarse material at 20~30℃ for 2-3 hours. S5. The coarse material processed in step S4 is mixed evenly with the binder and conductive agent through a mixer to obtain the first mixture. The first mixture is kept at 80~100℃ for 1-2 hours. S6. The fine material obtained in step S3 is mixed evenly with the active material and electrolyte through a mixer to obtain a second mixture; S7. Add the second mixture obtained in step S6 to the first mixture in step S5 for fiberization treatment. After the treatment is completed, recyclable dry electrode film powder is obtained.

[0006] Furthermore, in step S3, the coarse material that has undergone secondary crushing accounts for 20-30% of the total mass of all coarse material.

[0007] Furthermore, the silane coupling agent solution in step S4 is an ethanol solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0008] Furthermore, in step S4, the mass fraction of γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1-3%.

[0009] Furthermore, the binder and conductive agent used in step S5 are carbon nanotubes and polytetrafluoroethylene, respectively.

[0010] Furthermore, the mass ratio between the binder and the conductive agent used in step S5 is 1:(1~2), and the mass ratio between the total mass of the binder and the conductive agent and the mass of the remaining coarse material that has not undergone secondary crushing is 1:(8~10).

[0011] Furthermore, in step S6, the active material and the electrolyte are LiCoO2 and Li6PS5Cl, respectively.

[0012] Furthermore, in step S6, the mass ratio between the active material and the electrolyte is (2~4):1, and the mass ratio between the active material and the electrolyte and the fine material is (8~12):1.

[0013] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention effectively saves resources, reduces the total production cost of solid-state lithium batteries, and is beneficial to environmental protection by cutting off the irregular parts of the dry electrode film at its edge and recycling them. 2. In the recycling of dry electrode membranes, this invention pulverizes the dry electrode membranes into two particle sizes. First, the coarse material is combined with a binder to form a preliminary framework, and then combined with the fine material. This enhances the interfacial bonding ability between the recycled materials, reduces interfacial defects, and effectively improves the electrochemical performance of the batteries prepared from it. Attached Figure Description

[0014] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0015] The technical solutions of 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.

[0016] Please see Figure 1 The present invention provides: Example 1 A method for regenerating and reusing dry electrode films includes the following steps: S1. Weigh 200g of electrode film and freeze-dry it at -80℃ for 8 hours; S2. The dry electrode film treated in step S1 is pulverized once at 10°C to obtain coarse material with a particle size of 80 μm. S3. The 50g coarse material obtained in step S2 is crushed twice at 10℃ to obtain fine material with a particle size of 10um; S4. Spray a 2% (w / w) ethanol solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane onto the surface of the remaining 150g of coarse material that has not undergone secondary crushing, stir the coarse material, and vacuum dry it at 25°C for 2.5h. S5. The coarse material processed in step S4 is mixed evenly with 9.6g of conductive agent and 6.4g of binder through a mixer to obtain the first mixture. The first mixture is kept at 95℃ for 1.5h. S6. The fine material obtained in step S3 is mixed evenly with 375g of active material and 125g of electrolyte through a mixer to obtain a second mixture. S7. Add the second mixture obtained in step S6 to the first mixture in step S5 for fiberization treatment. After the treatment is completed, recyclable dry electrode film powder is obtained.

[0017] Example 2 A method for regenerating and reusing dry electrode films includes the following steps: S1. Weigh 200g of electrode film and freeze-dry it at -100℃ for 6h; S2. The dry electrode film treated in step S1 is pulverized once at 0°C to obtain coarse material with a particle size of 50 μm. S3. The 40g coarse material obtained in step S2 is crushed twice at 0℃ to obtain fine material with a particle size of 5um. S4. Spray a 1% (w / w) ethanol solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane onto the surface of the remaining coarse material that has not undergone secondary crushing, stir the coarse material, and vacuum dry it at 20°C for 2 hours. S5. The coarse material processed in step S4 is mixed evenly with 10g of conductive agent and 10g of binder through a mixer to obtain the first mixture. The first mixture is kept at 80℃ for 1 hour. S6. The fine material obtained in step S3 is mixed evenly with 213.3g of active material and 106.7g of electrolyte through a mixer to obtain a second mixture; S7. Add the second mixture obtained in step S6 to the first mixture in step S5 for fiberization treatment. After the treatment is completed, recyclable dry electrode film powder is obtained.

[0018] Example 3 A method for regenerating and reusing dry electrode films includes the following steps: S1. Weigh 200g of electrode film and freeze-dry it at -50℃ for 10h; S2. The dry electrode film treated in step S1 is pulverized once at 20°C to obtain coarse material with a particle size of 100 μm. S3. The 60g coarse material obtained in step S2 is crushed again at 20℃ to obtain fine material with a particle size of 20um; S4. Spray a 3% (w / w) ethanol solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane onto the surface of the remaining coarse material that has not undergone secondary crushing, stir the coarse material, and vacuum dry it at 30°C for 3 hours. S5. The coarse material processed in step S4 is mixed evenly with 9.3g of conductive agent and 4.7g of binder through a mixer to obtain the first mixture. The first mixture is kept at 100℃ for 2 hours. S6. The fine material obtained in step S3 is mixed evenly with 576g of active material and 144g of electrolyte through a mixer to obtain a second mixture. S7. Add the second mixture obtained in step S6 to the first mixture in step S5 for fiberization treatment. After the treatment is completed, recyclable dry electrode film powder is obtained.

[0019] In the above embodiment, the pulverizer speed is 1000 rpm in the first pulverization and 2000 rpm in the second pulverization; the mixing speed of the mixer is 500 rpm in step S5 and 1500 rpm in step S6; the shearing speed in the fiberization treatment in step S7 is Mach 1.2 and the treatment temperature is 140℃.

[0020] In the above embodiments, the binder is a fluoropolymer, specifically polytetrafluoroethylene; the conductive agent can be graphite or carbon nanotubes, specifically carbon nanotubes; the active material can be LiCoO2, LiMnO2, or LiTi5O2. 12The electrolyte is LiMnPO4, specifically LiCoO2; the electrolyte is Li6PS5Cl.

[0021] In this invention, the electrode film weighed in step S1 comes from the irregular part of the edge of the dry electrode film.

[0022] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that 50g of coarse material is still separated in step S3, but this 50g of coarse material is not crushed again. Two parts of coarse material are separated through the above steps. The processing steps of these two parts of coarse material are exactly the same as those of Example 1. 150g of coarse material is first mixed with binder and conductive agent, and 50g of coarse material is mixed with active material and electrolyte. Then the two are mixed and finally fiberized.

[0023] Comparative Example 2 The difference between Comparative Example 2 and Comparative Example 1 is that the electrode film was pulverized to 50 μm in one pulverization process, while the rest of the steps were exactly the same as those in Comparative Example 1.

[0024] Comparative Example 3 The difference between Comparative Example 3 and Comparative Example 1 is that the electrode film was pulverized to 20 μm in one pulverization process, while the rest of the steps were exactly the same as those in Comparative Example 1.

[0025] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the ethanol solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane sprayed in step S4 was replaced with the same amount of anhydrous ethanol. The remaining steps are exactly the same as in Example 1.

[0026] Seven groups of dry electrode film powders were prepared through Examples 1-3 and Comparative Examples 1-4 above. After being rolled into films, they were composited with current collectors to obtain positive electrode films.

[0027] The positive electrode films and electrolyte films obtained in Examples 1-3 and Comparative Examples 1-4, along with the Li-In negative electrode, were assembled into a single-layer pouch cell, and their electrochemical performance was tested. The test results are shown in Table 1 below. Table 1: Electrochemical performance test results of batteries prepared in Examples 1-3 and Comparative Examples 1-4 As can be seen from Table 1 above, Comparative Examples 1-3 did not vary the particle size of the electrode films and uniformly selected the same particle size. The electrochemical performance of the batteries prepared by these examples was weaker than that of Example 1. In Comparative Example 4, the electrochemical performance of the battery prepared without spraying an ethanol solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane was also significantly weaker than that of the battery in Example 1.

[0028] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for regenerating and utilizing dry electrode films, characterized in that, Includes the following steps: S1. Cut off the irregular part of the dry electrode film and then freeze-dry it at -100~-50℃ for 6~10h; S2. The dry electrode film treated in step S1 is pulverized once at 0~20℃ to obtain coarse material with a particle size of 50~100um; S3. A portion of the coarse material obtained in step S2 is pulverized a second time at 0~20℃ to obtain fine material with a particle size of 5~20um; S4. Spray silane coupling agent solution onto the surface of the remaining coarse material that has not undergone secondary crushing, stir the coarse material, and vacuum dry the coarse material at 20~30℃ for 2-3 hours. S5. The coarse material processed in step S4 is mixed evenly with the binder and conductive agent through a mixer to obtain the first mixture. The first mixture is kept at 80~100℃ for 1-2 hours. S6. The fine material obtained in step S3 is mixed evenly with the active material and electrolyte through a mixer to obtain a second mixture; S7. Add the second mixture obtained in step S6 to the first mixture in step S5 for fiberization treatment. After the treatment is completed, recyclable dry electrode film powder is obtained. The mass ratio between the binder and the conductive agent used in step S5 is 1:(1~2), and the mass ratio between the total mass of the binder and the conductive agent and the mass of the remaining coarse material that has not undergone secondary crushing is 1:(8~10).

2. The dry electrode film regeneration method according to claim 1, characterized in that, In step S3, the coarse material that has undergone secondary crushing accounts for 20-30% of the total mass of all coarse material.

3. The dry electrode film regeneration method according to claim 1, characterized in that, The silane coupling agent solution in step S4 is an ethanol solution of γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

4. The dry electrode film regeneration method according to claim 3, characterized in that, In step S4, the mass fraction of γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1-3%.

5. The dry electrode film regeneration method according to claim 1, characterized in that, The binder and conductive agent used in step S5 are carbon nanotubes and polytetrafluoroethylene, respectively.

6. The dry electrode film regeneration method according to claim 1, characterized in that, In step S6, the active substance and electrolyte are LiCoO2 and Li6PS5Cl, respectively.

7. The dry electrode film regeneration method according to claim 6, characterized in that, In step S6, the mass ratio between the active material and the electrolyte is (2~4):1, and the mass ratio between the active material and the electrolyte and the fine material is (8~12):1.

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