Recycling and processing method of pole piece and secondary battery

Abstract

The invention discloses a pole piece recycling and processing method and a secondary battery, the pole piece comprises a current collector and an active coating attached to the current collector, the processing method comprises the following steps: punching the pole piece to obtain another pole piece with an active coating, and the other pole piece is provided with a pole lug; a tab of the other pole piece is baked, the baking temperature ranges from 100 DEG C to 150 DEG C, and the baking time ranges from 2 min to 10 min; the baked tab is cleaned with ultrasonic waves, the ultrasonic frequency ranges from 20 kHz to 70 kHz, and the cleaning time ranges from 5 min to 10 min; removing residues attached to the tabs; and cleaning the tab by using an organic solution. According to the secondary battery, the electrode is manufactured by using the recycling and processing method of the electrode piece. According to the method, the active coating is baked through hot air, so that the active coating is cracked, and subsequent removal of the active coating is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion batteries, and in particular to a pole piece recycling processing method and a secondary battery. Background Art

[0002] During the research and development of battery models, it is necessary to conduct cycle life tests on large aluminum shell cells. When the battery decays to different stages, it is necessary to analyze the life decay mechanism of the battery. Usually, the large aluminum shell cells that have decayed to a certain SOH are disassembled to obtain low-power positive and negative electrode sheets, diaphragms, electrolytes and other materials. The charged positive and negative electrode sheets are punched, tab processed, stacked, packaged, injected, charged and discharged to assemble them into the required soft-pack batteries, symmetrical batteries and soft-pack three-electrodes. The prepared soft-pack batteries are used to carry out relevant electrochemical tests (EIS, capacity test, lithium precipitation boundary test, etc.) to study the main influencing factors of battery degradation, and to optimize the main aging factors that affect the life, thereby improving the life of new models of batteries.

[0003] After the pole piece has been charged and discharged many times in the battery, the active coating is more tightly bonded to the current collector. The traditional methods of sticking with tape, soaking in solvents and wiping cannot effectively remove the active coating. Therefore, most people currently use manual blades to scrape the disassembled pole pieces and pole ears to remove the active coating on their surfaces. However, this method is inefficient, has a poor effect in removing the active coating, and the pole ears are easily damaged, resulting in the pole ears being unable to pass ultrasonic welding. Summary of the invention

[0004] In order to overcome the defects in the prior art, the present invention provides a pole piece recycling processing method and a secondary battery. The method bakes the active coating with hot air to crack the active coating, thereby facilitating the subsequent removal of the active coating.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for recycling a pole piece, wherein the pole piece includes a current collector and an active coating attached to the current collector, comprising the following steps:

[0006] Punching the pole piece to obtain another pole piece with an active coating, wherein the other pole piece has a pole ear;

[0007] Baking the tab of the other pole piece at a temperature between 100° C. and 150° C. for a time period of 2 min to 10 min;

[0008] Use ultrasonic cleaning to clean the baked tabs, the ultrasonic frequency is 20kHz-70kHz, and the cleaning time is 5min~10min;

[0009] Dry grinding the tab to remove residues attached to the tab;

[0010] Use organic solution to clean the tabs.

[0011] Furthermore, when the tab is baked, the tab is kept rotating at a speed of 180° to 360° per minute to ensure that the active coating on the surface of the tab is heated evenly.

[0012] Furthermore, the electrode sheet includes a positive electrode sheet and a negative electrode sheet, and the other electrode sheet includes a new positive electrode sheet and a new negative electrode sheet. The new positive electrode sheet is obtained by punching the positive electrode sheet, and the new negative electrode sheet is obtained by punching the negative electrode sheet.

[0013] Furthermore, when the tabs of the new negative electrode are baked, the baking time is 3 minutes to 5 minutes. When the tabs of the new positive electrode are baked, the baking time is 3 minutes to 8 minutes. Since the active coating of the negative electrode is generally composed of carbon materials, and the active coating of the positive electrode is generally composed of materials such as lithium iron phosphate, lithium nickel cobalt manganate, etc., the active coating of the positive electrode is more heat-resistant, so the active coating of the positive electrode needs to be baked for a longer time.

[0014] Furthermore, when baking the tab, when visually visible cracks appear on the active coating on the surface of the tab, baking is stopped. The active coating is easier to remove after cracking.

[0015] Further, the baked tabs are cleaned using ultrasonic waves, and the cleaning steps are as follows:

[0016] Injecting an organic solvent into a containing tank of an ultrasonic cleaning device, wherein the liquid level of the organic solvent can just immerse the tab;

[0017] Immersing at least one or more electrode tabs of another stacked electrode sheet in the organic solvent;

[0018] The ultrasonic cleaning device emits ultrasonic waves to clean the tabs.

[0019] Wherein, the organic solvent is at least one of N-methylpyrrolidone, dimethyl carbonate, diethyl carbonate, ethylene carbonate and anhydrous ethanol.

[0020] Further, removing the residue attached to the tab includes:

[0021] Grinding the surface of the tab using a grinding device;

[0022] Sticking the tape on the surface of the tab, and then tearing off the tape after waiting for 5s to 10s to remove the residue attached to the surface of the tab;

[0023] The adhesive tape includes one or more of grid adhesive tape, transparent adhesive tape and PVC adhesive tape.

[0024] Wherein, the residues include active coating residues and the carbon coating layer of the positive electrode plate.

[0025] Further, using an organic solution to clean the tabs includes:

[0026] A practical cleaning tool is dipped in anhydrous ethanol to wipe the tab, wherein the cleaning tool comprises dust-free paper.

[0027] A secondary battery comprises an electrode processed by the above-mentioned electrode sheet recycling method.

[0028] By means of the above technical solution, the beneficial effects of the present invention are as follows:

[0029] 1. In this application, the active coating is baked by hot air to crack the active coating, which is convenient for subsequent removal of the active coating;

[0030] 2. The present application uses an ultrasonic cleaning device to clean the cracked active coating, and uses a grinding device to clean the tabs cleaned by the ultrasonic cleaning device to ensure that the active coating is cleaned.

[0031] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0033] Figure 1 is a schematic diagram of punching another pole piece with a pole piece in an embodiment of the present invention;

[0034] Figure 2 is a schematic diagram of using a hot air gun to bake a tab in an embodiment of the present invention;

[0035] Figure 3 It is a schematic diagram of cleaning a pole ear in a receiving chamber of an ultrasonic cleaner according to an embodiment of the present invention.

[0036] The reference numerals of the above drawings are: 1. another pole piece; 11. pole ear; 2. hot air gun; 3. electric rotary clamp; 4. receiving groove. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] It should be noted that, in the description of the present invention, the terms "first", "second", etc. are only used for descriptive purposes and to distinguish similar objects. There is no order of precedence between the two, and they cannot be understood as indicating or implying relative importance. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0039] Example: Combination Figure 1-3 As shown, this embodiment discloses a method for recycling a pole piece, wherein the pole piece is obtained by disassembling a battery after life decay, and the pole piece includes a current collector and an active coating attached to the current collector. The processing method includes the following steps:

[0040] Punching the pole piece to obtain another pole piece with an active coating, wherein the other pole piece has a pole ear;

[0041] Baking the tab of the other pole piece at a temperature between 100° C. and 150° C. for a time period of 2 min to 10 min;

[0042] Use ultrasonic cleaning to clean the baked tabs, the frequency of the ultrasonic wave is 20kHz-70kHz, and the cleaning time is 5min~10min;

[0043] Dry grinding the tab to remove residues attached to the tab;

[0044] Use organic solution to clean the tabs.

[0045] Another pole piece 1 with a clean and smooth pole ear 11 is obtained through the above-mentioned pole piece recycling processing method, which is used to make a soft-pack battery, a symmetrical battery or a soft-pack three-electrode.

[0046] Among them, a cutting die is used to punch out the electrode piece, and the size of the cutting die can be customized according to the size of the soft-pack battery, symmetrical battery or soft-pack three-electrode battery to be manufactured.

[0047] In the present application, when baking the tab of the other pole piece, a hot air gun 2 is used to provide hot air baking. During the process of using the hot air gun 2 to bake the tab 11, the hot air gun 2 or the tab 11 is kept rotating so that the active coating on the surface of the tab 11 is evenly heated. In the present application, the staff holds the hot air gun 2 to bake the tab 11. During baking, the staff continuously adjusts the baking angle of the hot air gun 2 to ensure that the active coating on the surface of the tab 11 is evenly heated. It should be noted that the pole piece includes a positive pole piece and a negative pole piece, and the other pole piece 1 includes a new positive pole piece and a new negative pole piece. The positive pole piece is punched to obtain a new positive pole piece, and the negative pole piece is punched to obtain a new negative pole piece. Since the active coating of the negative pole piece is generally composed of carbon materials, and the active coating of the positive pole piece is generally composed of materials such as lithium iron phosphate, lithium nickel cobalt manganate, etc., the active coating of the positive pole piece is more heat-resistant, so the active coating of the positive pole piece needs to be baked for a longer time. When baking the tab 11, the hot air temperature provided by the hot air gun 2 is between 100°C and 150°C. Stop the baking step until the active coating on the surface of the tab 11 shows obvious cracks. Baking the active coating until it cracks makes it easier to remove. Generally, when baking the tab 11 of the new negative electrode sheet, the hot air gun 2 works for 3min to 5min, and obvious cracks can be observed in the active coating on the surface of the tab 11. When baking the tab 11 of the new positive electrode sheet, the hot air gun 2 works for 3min to 8min, and obvious cracks can be observed in the active coating on the surface of the tab 11.

[0048] After the pole piece has been charged and discharged many times in the battery, the active coating is more tightly bonded to the current collector, and the active coating cannot be effectively removed by conventional methods such as adhesive tape, solvent soaking and wiping. In the present application, the active coating on the surface of the pole piece is baked by a hot air gun 2 to crack it, thereby making it easier to remove the active coating on the surface of the other pole piece 1.

[0049] In another feasible embodiment, the other pole piece 1 is clamped by an electric rotating clamp 3, and the relative positions of the hot air gun 2 and the electric rotating clamp 3 are fixed so that the pole tab 11 is located at the air outlet of the hot air gun 2. During baking, the electric rotating clamp 3 is used to drive the other pole piece 1 to rotate at a constant speed. This solution can further ensure that the active coating on the surface of the pole tab 11 is heated evenly and saves human resources. Figure 1 As shown, the electric rotating clamp 3 clamps the other pole piece 1 from above on the side away from the pole ear 11, so that the other pole piece 1 is inverted. The hot air gun 2 is arranged on the side of the other pole piece 1, and the air outlet of the hot air gun 2 is opposite to the pole ear 11. During the baking process, the electric rotating clamp 3 drives the other pole piece 1 to rotate with the vertical direction as the axis, and the rotation speed is 180° to 360° per minute.

[0050] In the present application, an ultrasonic cleaner is used to clean the baked pole piece 11, and an organic solvent is injected into the receiving tank 4 of the ultrasonic cleaner, and the organic solvent is at least one of N-methylpyrrolidone, dimethyl carbonate, diethyl carbonate, ethylene carbonate, and anhydrous ethanol. Stack a plurality of other pole pieces 1, and place the pole piece 11 in the organic solvent, start the ultrasonic cleaner for cleaning, until the active coating on the surface of the pole piece 11 is basically removed, and take out the other pole piece 1. Generally, cleaning for 5min to 10min is sufficient. It should be noted that the liquid level of the organic solvent needs to be controlled to just immerse the pole piece 11, so as to avoid damage to the pole piece body of the other pole piece 1 as much as possible. In the present application, the purpose of the liquid level of the organic solvent just immersing the pole piece 11 is achieved by controlling the depth of the organic solvent to be equal to the height of the pole piece 11.

[0051] In this application, an electric grinder is used to grind the surface of the pole ear 11 to clean the active coating residues and the carbon coating layer of the positive electrode plate that are still attached to the surface of the pole ear 11 after cleaning with an ultrasonic cleaner. This application uses a scouring pad grinding head, which can skillfully grind the active coating residues and the carbon coating layer clean while avoiding damage to the current collector. After grinding, use transparent tape to stick it on the surface of the pole ear, wait for 5s to 10s and then tear off the tape to remove the residue attached to the surface of the pole ear. Among them, the carbon coating layer is an additive for the positive electrode plate.

[0052] Optionally, the transparent tape can be replaced by any tape such as grid tape or PVC tape.

[0053] Finally, use dust-free paper dipped in anhydrous ethanol to wipe the pole tab 11 to obtain another pole piece 1 with a clean pole tab 11.

[0054] Optionally, the dust-free paper can be replaced with cleaning tools such as cotton swabs, sticky sticks, lens wiping sticks, and dust removal sticks.

[0055] Compared with the traditional method of scraping the disassembled pole pieces and pole ears with a manual blade to remove the active coating on their surfaces, the pole piece recycling processing method disclosed in the present application is more efficient and has a better effect of removing the active coating.

[0056] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for recycling a pole piece, wherein the pole piece comprises a current collector and an active coating attached to the current collector, characterized in that: The following steps are involved: Punching the pole piece to obtain another pole piece with an active coating, wherein the other pole piece has a pole ear; Baking the tab of the other pole piece at a temperature between 100° C. and 150° C. for a time period of 2 min to 10 min; Use ultrasonic cleaning to clean the baked tabs, the ultrasonic frequency is 20kHz-70kHz, and the cleaning time is 5min~10min; Dry grinding the tab to remove residues attached to the tab; Use organic solution to clean the tabs.

2. The pole piece recycling method according to claim 1, characterized in that: When the tab is baked, the tab is kept rotating, and the rotation speed of the tab is 180° to 360° per minute.

3. The pole piece recycling method according to claim 2, characterized in that: When the other electrode sheet is a negative electrode sheet, the duration of baking the electrode tab is 3 minutes to 5 minutes.

4. The pole piece recycling method according to claim 2, characterized in that: When the other electrode piece is a positive electrode piece, the time for baking the electrode ear is 3 minutes to 8 minutes.

5. The pole piece recycling method according to claim 2, characterized in that: When baking the tab, the baking is stopped when visually visible cracks appear on the active coating on the surface of the tab.

6. The pole piece recycling method according to claim 1 or 3, characterized in that: The step of using ultrasonic cleaning to clean the baked tabs also includes the following steps: Injecting an organic solvent into a holding tank of an ultrasonic cleaning device; Immersing at least one or more electrode tabs of another stacked electrode sheet in the organic solvent; The ultrasonic cleaning device emits ultrasonic waves to clean the tabs.

7. The pole piece recycling method according to claim 6, characterized in that: The organic solvent is at least one of N-methylpyrrolidone, dimethyl carbonate, diethyl carbonate, ethylene carbonate and anhydrous ethanol.

8. The pole piece recycling method according to claim 1, characterized in that: Removing the residue attached to the tab includes: Grinding the surface of the tab using a grinding device; Sticking the tape on the surface of the tab, and then tearing off the tape after waiting for 5s to 10s to remove the residue attached to the surface of the tab; Wherein, the adhesive tape includes one or more of grid adhesive tape, transparent adhesive tape, and PVC adhesive tape.

9. The pole piece recycling method according to claim 1, characterized in that: Cleaning tabs using organic solutions includes: Use a practical cleaning tool dipped in anhydrous ethanol to wipe the tab.

10. A secondary battery, characterized in that: The secondary battery comprises an electrode processed by the electrode piece recycling method according to any one of claims 1 to 9.

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