Method and equipment for removing burrs of battery pole piece

Abstract

The invention provides a method and equipment for removing burrs of a battery pole piece. The method comprises the following steps: when a rolled battery pole piece is slit, coating the edge side of the striped pole piece by adopting a deburring agent, so as to prevent the generation of pole piece burrs. In the slitting process of the battery pole piece, the burr removing agent is used for coating the edge side with burrs of the striped pole piece, so that the generation of the burrs of the pole piece can be directly avoided, the utilization rate of the slit pole piece and the yield of the battery are improved, the pole piece can be ensured not to be damaged, the improvement of the electrochemical performance of the battery is facilitated, and the service life of the battery is prolonged. And the method is simple in process and low in cost, does not cause excessive change on the existing production line, and has great industrial application potential.

Description

Technical Field

[0001] The present invention belongs to the field of battery processing, and particularly relates to a method and device for removing burrs from battery electrode sheets. Background Art

[0002] Lithium batteries are a type of battery with lithium metal or lithium alloy as the positive / negative electrode material and using a non-aqueous electrolyte solution. Lithium batteries include a positive electrode sheet and a negative electrode sheet, which are respectively prepared with aluminum foil and copper foil as the base materials. During the preparation process, it is necessary to slit the mother roll of the electrode sheet according to the size of the finished battery. However, when the battery electrode sheet is slit, burrs of different sizes, lengths, and uneven distributions are easily generated at the edge of the electrode sheet. After the slit electrode sheet enters the next process, the burrs are likely to pierce the packaging of the lithium battery, resulting in liquid leakage and scrapping of the electrode sheet, which greatly reduces the utilization rate of materials.

[0003] For this reason, Patent CN101068045A discloses a method for removing burrs from battery electrode sheets. The method includes the following steps: a) Fix the battery electrode sheet with burrs at the edge after cutting with a fixture; b) Start the deburring edge rolling machine, and roll the edge of the battery electrode sheet through the roller of the edge rolling machine, so that the edge of the battery electrode sheet converges inward, thereby completing the process of removing burrs from the battery electrode sheet. Although this patent uses a roller to roll the edge of the battery electrode sheet to achieve the purpose of removing burrs at the shearing part of the battery electrode sheet, the effect of removing burrs at the shearing part of the electrode sheet is very limited and the effect is not ideal.

[0004] Patent CN102903886A discloses a method for removing burrs from battery electrode sheets by dry etching, that is, using an induction coil to ionize the reaction gas, so that the ionized reaction particles bombard the surface of the burrs on the battery electrode sheet under the DC bias, and the burrs at the edge of the battery electrode sheet workpiece are eliminated under the physical bombardment effect, so as to achieve the elimination of edge burrs caused by workpiece processing. This patent has low efficiency, high cost, and may also cause damage to the edge of the electrode sheet.

[0005] Therefore, there is an urgent need to provide a method for removing burrs from electrode sheets at low cost and high efficiency to improve the utilization rate of slit electrode sheets and the yield of batteries, while ensuring that the electrode sheets are not damaged. Summary of the Invention

[0006] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a method and device for removing burrs from battery electrodes. During the slitting process of the battery electrode, a deburring agent is used to coat the edge side of the slit electrode with burrs, which can not only directly prevent the generation of electrode burrs, improve the utilization rate of the slit electrode and the yield of the battery, but also ensure that the electrode is not damaged, contribute to the improvement of the electrochemical performance of the battery, and the method has a simple process, low cost, and will not cause excessive changes to the existing production line, and has great potential for industrial application.

[0007] To achieve the purpose of this invention, the following technical solutions are adopted:

[0008] In the first aspect, the present invention provides a method for removing burrs from battery electrodes, and the method includes the following steps:

[0009] When slitting the rolled battery electrode, a deburring agent is used to coat the edge side of the slit electrode, thereby preventing the generation of electrode burrs.

[0010] During the slitting process of the battery electrode, a deburring agent is used to coat the edge side of the slit electrode with burrs, which can not only directly prevent the generation of electrode burrs, improve the utilization rate of the slit electrode and the yield of the battery, but also ensure that the electrode is not damaged, contribute to the improvement of the electrochemical performance of the battery, and the method has a simple process, low cost, and will not cause excessive changes to the existing production line, and has great potential for industrial application.

[0011] It should be noted that the slit electrode refers to the battery electrode during the slitting process.

[0012] Preferably, the coating method includes the spraying method.

[0013] It should be noted that the spraying flow rate of the deburring agent in the spraying method is set according to the running speed of the slitting device.

[0014] In the present invention, the spraying flow rate of the deburring agent is set according to the running speed of the slitting device, which helps to fully wrap or decompose the burrs on the electrode during the slitting process, and has a high spraying efficiency. In industrial production, it can make the production line run continuously and efficiently, reduce the time for shutdown adjustment, improve production efficiency, and reduce production costs.

[0015] Preferably, during the coating process, the slitting speed of the slitting device is 10 - 30 m / s, for example, it can be 10 m / s, 15 m / s, 20 m / s, 25 m / s, or 30 m / s, etc.

[0016] Preferably, the particle size of the deburring agent is 0.1-10 μm, for example, it can be 0.1 μm, 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm, etc., and preferably 4-6 μm.

[0017] In the present invention, the deburring agent with an appropriate particle size can prevent the generation of burrs while having no adverse effect on the surface of the electrode sheet.

[0018] Preferably, the distance between the area where the edge side of the slit electrode sheet is coated and the edge of the electrode sheet is 0.5-1 mm, for example, it can be 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm or 1 mm, etc.

[0019] It should be noted that the distance refers to the shortest distance from the edge of the slit electrode sheet to the boundary of the coated area in the direction perpendicular to the edge of the slit electrode sheet. In the present invention, an appropriate coating area is conducive to fully wrapping or dissolving burrs.

[0020] Preferably, the battery electrode sheet is a positive electrode sheet.

[0021] Preferably, the positive electrode sheet includes a binder, and the binder includes any one or a combination of at least two of PVDF (polyvinylidene fluoride), CMC or Teflon.

[0022] It should be noted that the outer layer material of the separator co-assembled with the positive electrode sheet can also be any one or a combination of at least two of PVDF, CMC or Teflon.

[0023] Preferably, the deburring agent includes any one or a combination of at least two of PVDF, CMC or Teflon.

[0024] In the present invention, selecting the above types of deburring agents for application to the positive electrode sheet can not only prevent the generation of burrs, but also have no adverse effect on the positive electrode sheet.

[0025] Preferably, the battery electrode sheet is a negative electrode sheet.

[0026] Preferably, the negative electrode sheet includes a binder, and the binder includes CMC (sodium carboxymethyl cellulose).

[0027] Preferably, the deburring agent includes CMC.

[0028] In the present invention, selecting the above types of deburring agents for application to the negative electrode sheet can not only prevent the generation of burrs, but also have no adverse effect on the negative electrode sheet.

[0029] Preferably, after the coating treatment, the burrs are wrapped or decomposed.

[0030] In a second aspect, the present invention provides a device for removing burrs from battery electrode sheets, and the method as described in the first aspect is carried out in the device. The device includes:

[0031] A slitting device, the slitting device includes a pressure roller, and the slitting device is used for slitting the rolled battery electrode sheet.

[0032] A coating device, the coating device is located on both sides of the pressure roller of the slitting device, and is used for outputting a deburring agent to coat the edge sides of the slit electrode sheets.

[0033] Preferably, the coating device includes a spraying device.

[0034] Preferably, the ratio of the slitting speed of the slitting device to the spraying speed of the spraying device is (0.8 - 1.2):(0.8 - 1.2). Among them, the selection range "0.8 - 1.2" of the slitting device can be, for example, 0.8, 0.9, 1, 1.1, or 1.2, etc., and the selection range "0.8 - 1.2" of the spraying device can be, for example, 0.8, 0.9, 1, 1.1, or 1.2, etc.

[0035] In the present invention, the suitable slitting speed of the slitting device and the spraying speed of the spraying device cooperate with each other, which can fully wrap or decompose the edge burrs of the electrode sheet during the slitting process, with high efficiency and low cost.

[0036] Preferably, the device further includes an adjusting device, and the coating device is arranged on the adjusting device so that the position of the coating device relative to the edge of the electrode sheet during slitting by the slitting device is adjustable.

[0037] In the present invention, realizing that the position of the coating device relative to the edge of the electrode sheet during slitting by the slitting device is adjustable can accurately match the coating area with the edge position of the slit electrode sheet, ensure the accurate coating position of the electrode sheet, thereby improving the quality and consistency of the electrode sheet; when producing battery electrode sheets of different models and specifications, it can quickly adapt to changes, without the need to replace or largely adjust the equipment, reducing costs and greatly improving the production flexibility and equipment versatility.

[0038] The numerical ranges described in the present invention not only include the above-listed point values, but also include any point values between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, the present invention does not exhaustively list the specific point values included in the ranges.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] During the slitting process of the battery electrode sheet, the burr-free agent is used to coat the burr-containing edge side of the slit electrode sheet. This can not only directly prevent the generation of burrs on the electrode sheet, improve the utilization rate of the slit electrode sheet and the yield of the battery, but also ensure that the electrode sheet is not damaged, which helps to improve the electrochemical performance of the battery. Moreover, this method has a simple process, low cost, and will not cause excessive changes to the existing production line, and has great potential for industrial application. Detailed Embodiments

[0041] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations to the present invention.

[0042] In a specific embodiment, the present invention provides a device for removing burrs from battery electrode sheets, and the device includes:

[0043] A slitting device, the slitting device includes a pressure roller, and the slitting device is used for slitting the roller-pressed battery electrode sheet.

[0044] An infusion spraying device, the infusion spraying device is located on both sides of the pressure roller of the slitting device, and is used to output the burr-free agent to spray the edge side of the slit electrode sheet.

[0045] An adjusting device, the infusion spraying device is arranged on the adjusting device so that the position of the infusion spraying device relative to the edge of the electrode sheet during slitting by the slitting device is adjustable.

[0046] Specifically, the ratio of the slitting speed of the slitting device to the spraying speed of the infusion spraying device is (0.8 - 1.2):(0.8 - 1.2). Among them, the selection range "0.8 - 1.2" of the slitting device can be, for example, 0.8, 0.9, 1, 1.1, or 1.2, etc., and the selection range "0.8 - 1.2" of the infusion spraying device can be, for example, 0.8, 0.9, 1, 1.1, or 1.2, etc.

[0047] Example 1

[0048] This example provides a method for removing burrs from the positive electrode sheet. The method uses the above-mentioned device and includes the following steps:

[0049] (1) Provide a roller-pressed positive electrode sheet; wherein, the positive electrode sheet includes a current collector aluminum foil, and a positive electrode active layer provided on the surface of the current collector aluminum foil. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is lithium iron phosphate, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

[0050] (2) Perform slitting on the roller-pressed positive electrode sheet, and during slitting, spray the edge side of the slit sheet with a deburring agent to prevent the generation of burrs on the sheet.

[0051] Among them, the deburring agent is polyvinylidene fluoride, and the particle size of the deburring agent is 5 μm; during the spraying process, the slitting speed of the slitting device is 20 m / s, and the ratio of the slitting speed of the slitting device to the spraying speed of the infusion spraying device is 1:1; the distance between the area where the edge side of the slit sheet is sprayed and the edge of the slit sheet is 0.8 mm.

[0052] Example 2

[0053] This example provides a method for removing burrs from a positive electrode sheet. The method uses the above-mentioned equipment and includes the following steps:

[0054] (1) Provide a roller-pressed positive electrode sheet; among them, the positive electrode sheet includes a current collector aluminum foil and a positive electrode active layer provided on the surface of the current collector aluminum foil. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is lithium iron phosphate, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

[0055] (2) Perform slitting on the roller-pressed positive electrode sheet, and during slitting, spray the edge side of the slit sheet with a deburring agent to prevent the generation of burrs on the sheet.

[0056] Among them, the deburring agent is polyvinylidene fluoride, and the particle size of the deburring agent is 0.1 μm; during the spraying process, the slitting speed of the slitting device is 10 m / s, and the ratio of the slitting speed of the slitting device to the spraying speed of the infusion spraying device is 0.8:1.2; the distance between the area where the edge side of the slit sheet is sprayed and the edge of the slit sheet is 0.5 mm.

[0057] Example 3

[0058] This example provides a method for removing burrs from a positive electrode sheet. The method uses the above-mentioned equipment and includes the following steps:

[0059] (1) Provide a roller-pressed positive electrode sheet; among them, the positive electrode sheet includes a current collector aluminum foil and a positive electrode active layer provided on the surface of the current collector aluminum foil. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is lithium iron phosphate, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

[0060] (2) Perform slitting on the roll-pressed positive electrode sheet, and during slitting, spray the edge side of the slit sheet with a deburring agent to prevent the generation of burrs on the sheet.

[0061] Among them, the deburring agent is polyvinylidene fluoride, and the particle size of the deburring agent is 10 μm; during the spraying process, the slitting speed of the slitting device is 30 m / s, and the ratio of the slitting speed of the slitting device to the spraying speed of the infusion spraying device is 1.2:0.8; the distance between the area where the edge side of the slit sheet is sprayed and the edge of the slit sheet is 1 mm.

[0062] Example 4

[0063] This example provides a method for removing burrs from a negative electrode sheet. The method uses the equipment described above and includes the following steps:

[0064] (1) Provide a roll-pressed negative electrode sheet; among them, the negative electrode sheet includes a current collector copper foil and a negative electrode active layer provided on the surface of the current collector copper foil. The negative electrode active layer includes a negative electrode active material, a conductive agent, and a binder. The negative electrode active material is natural graphite, the conductive agent is acetylene black, and the binder is sodium carboxymethyl cellulose.

[0065] (2) Perform slitting on the roll-pressed negative electrode sheet, and during slitting, spray the edge side of the slit sheet with a deburring agent to prevent the generation of burrs on the sheet.

[0066] Among them, the deburring agent is sodium carboxymethyl cellulose, and the particle size of the deburring agent is 5 μm; during the spraying process, the slitting speed of the slitting device is 20 m / s, and the ratio of the slitting speed of the slitting device to the spraying speed of the infusion spraying device is 1:1; the distance between the area where the edge side of the slit sheet is sprayed and the edge of the slit sheet is 0.8 mm.

[0067] Example 5

[0068] This example provides a method for removing burrs from a positive electrode sheet. The method uses the equipment described above and includes the following steps:

[0069] (1) Provide a roll-pressed positive electrode sheet; among them, the positive electrode sheet includes a current collector aluminum foil and a positive electrode active layer provided on the surface of the current collector aluminum foil. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is lithium iron phosphate, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

[0070] (2) Perform slitting on the roll-pressed positive electrode sheet, and during slitting, spray the edge side of the slit sheet with a deburring agent to prevent the generation of burrs on the sheet.

[0071] Among them, the deburring agent is polyvinylidene fluoride, and the particle size of the deburring agent is 5 μm; during the spraying process, the slitting speed of the slitting device is 5 m / s, and the ratio of the slitting speed of the slitting device to the spraying speed of the infusion spraying device is 1:1; the distance between the area sprayed on the edge side of the slit sheet and the edge of the slit sheet is 0.8 mm.

[0072] Example 6

[0073] This example provides a method for removing burrs from a positive electrode sheet. The method uses the above-mentioned equipment and includes the following steps:

[0074] (1) Provide a roll-pressed positive electrode sheet; among them, the positive electrode sheet includes a current collector aluminum foil, and a positive electrode active layer provided on the surface of the current collector aluminum foil. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is lithium iron phosphate, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

[0075] (2) Perform slitting on the roll-pressed positive electrode sheet, and during slitting, spray the edge side of the slit sheet with a deburring agent to prevent the generation of burrs on the sheet.

[0076] Among them, the deburring agent is polyvinylidene fluoride, and the particle size of the deburring agent is 5 μm; during the spraying process, the slitting speed of the slitting device is 35 m / s, and the ratio of the slitting speed of the slitting device to the spraying speed of the infusion spraying device is 1:1; the distance between the area sprayed on the edge side of the slit sheet and the edge of the slit sheet is 0.8 mm.

[0077] Example 7

[0078] This example provides a method for removing burrs from a positive electrode sheet. The method uses the above-mentioned equipment and includes the following steps:

[0079] (1) Provide a roll-pressed positive electrode sheet; among them, the positive electrode sheet includes a current collector aluminum foil, and a positive electrode active layer provided on the surface of the current collector aluminum foil. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is lithium iron phosphate, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

[0080] (2) Perform slitting on the rolled positive electrode sheet, and during slitting, spray the edge side of the slit electrode sheet with a deburring agent to prevent the generation of burrs on the electrode sheet.

[0081] Among them, the deburring agent is polyvinylidene fluoride, and the particle size of the deburring agent is 50 nm; during the spraying process, the slitting speed of the slitting device is 20 m / s, and the ratio of the slitting speed of the slitting device to the spraying speed of the infusion-type spraying device is 1:1; the distance between the area sprayed on the edge side of the slit electrode sheet and the edge of the slit electrode sheet is 0.8 mm.

[0082] Example 8

[0083] This example provides a method for removing burrs from a positive electrode sheet. The method uses the above-mentioned equipment and includes the following steps:

[0084] (1) Provide a rolled positive electrode sheet; among them, the positive electrode sheet includes a current collector aluminum foil, and a positive electrode active layer provided on the surface of the current collector aluminum foil. The positive electrode active layer includes a positive electrode active material, a conductive agent, and a binder. The positive electrode active material is lithium iron phosphate, the conductive agent is acetylene black, and the binder is polyvinylidene fluoride.

[0085] (2) Perform slitting on the rolled positive electrode sheet, and during slitting, spray the edge side of the slit electrode sheet with a deburring agent to prevent the generation of burrs on the electrode sheet.

[0086] Among them, the deburring agent is polyvinylidene fluoride, and the particle size of the deburring agent is 20 μm; during the spraying process, the slitting speed of the slitting device is 20 m / s, and the ratio of the slitting speed of the slitting device to the spraying speed of the infusion-type spraying device is 1:1; the distance between the area sprayed on the edge side of the slit electrode sheet and the edge of the slit electrode sheet is 0.8 mm.

[0087] Performance test

[0088] Prepare a lithium-ion battery based on the positive electrode sheet or negative electrode sheet provided in the above example, and then conduct a first charge-discharge efficiency test and a safety performance test on the lithium-ion battery.

[0089] Assembly method of lithium-ion battery:

[0090] Using the positive electrode sheet provided above as the positive electrode sheet, a graphite negative electrode sheet as the negative electrode sheet, a polyethylene separator, and the outer surface of the separator is coated with PVDF. The electrolyte is a carbonate solution containing lithium hexafluorophosphate, and its solvent includes ethylene carbonate and dimethyl carbonate with a volume ratio of 1:1; assemble the positive electrode sheet, negative electrode sheet, separator, and electrolyte to obtain a lithium-ion battery. Or,

[0091] Using the negative electrode tab provided above as the negative electrode tab, the lithium iron phosphate positive electrode tab as the positive electrode tab, a polyethylene separator, and the outer surface of the separator is coated with CMC, and the electrolyte is a carbonate solution containing lithium hexafluorophosphate, and its solvent includes ethylene carbonate and dimethyl carbonate with a volume ratio of 1:1; assembling the positive electrode tab, negative electrode tab, separator and electrolyte can obtain a lithium ion battery.

[0092] Conditions for the first charge-discharge efficiency test: The test ambient temperature is controlled at 25°C ± 2°C, charged to the full charge state of the battery cell at a current of 0.5C, and then discharged to 3.0V at a current of 0.5C.

[0093] Conditions for the safety performance test: Use a steel needle to penetrate the battery and monitor whether it catches fire or explodes.

[0094] The results of the above tests are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] Note: The K value refers to the voltage drop of the battery per unit time.

[0099] Analysis:

[0100] It can be seen from the comparison between Example 1 and Examples 5-6 that if the spraying flow rate of the deburring agent is too small, it is difficult to completely eliminate the generation of burrs on the electrode tab, which will have an adverse impact on the first charge-discharge efficiency and safety performance of the battery; if the spraying flow rate of the deburring agent is too large, it is not conducive to the performance of the battery's electrical properties, resulting in a low first efficiency of the battery and an adverse impact on the safety performance.

[0101] It can be seen from the comparison between Example 1 and Examples 7-8 that if the particle size of the deburring agent is too small, the deburring efficiency is low, and it may damage the electrode tab, which is not conducive to improving the adverse impact of burrs on the safety performance of the battery; if the particle size of the deburring agent is too large, it is easy to cause damage to the electrode tab and incomplete burr removal, which is not conducive to the performance of the battery's electrical properties, resulting in a low first efficiency of the battery.

[0102] The applicant declares that the present invention uses the above examples to illustrate the process method of the present invention, but the present invention is not limited to the above examples, that is, it does not mean that the present invention must rely on the above examples to be implemented. Those skilled in the art should understand that any improvement to the present invention, the equivalent replacement of each raw material of the present invention's product, the addition of auxiliary components, and the selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for removing burrs from a battery pole piece, characterized in that: The method comprises the following steps: When the battery pole pieces are cut after rolling, a deburring agent is used to coat the edge sides of the stripped pole pieces, thereby preventing the generation of pole piece burrs.

2. The method according to claim 1, characterized in that The coating treatment method includes spraying; Preferably, during the coating process, the slitting speed of the slitting device is 10-30 m / s.

3. The method according to claim 1 or 2, characterized in that: The particle size of the deburring agent is 0.1-10 μm, preferably 4-6 μm.

4. The method according to any one of claims 1 to 3, characterized in that: The distance between the area where the coating treatment is performed on the edge side of the stripped pole piece and the edge of the pole piece is 0.5-1 mm.

5. The method according to any one of claims 1 to 4, characterized in that: The battery pole piece is a positive pole piece; The positive electrode sheet includes a binder, and the binder includes any one of PVDF, CMC or Teflon or a combination of at least two thereof; The deburring agent includes any one of PVDF, CMC or Teflon or a combination of at least two of them.

6. The method according to any one of claims 1 to 4, characterized in that: The battery pole piece is a negative pole piece; The negative electrode sheet includes a binder, and the binder includes CMC; The deburring agent includes CMC.

7. The method according to any one of claims 1 to 6, characterized in that: After the coating process, the burrs are encapsulated or decomposed.

8. A device for removing burrs from battery pole pieces, characterized in that: The method according to any one of claims 1 to 7 is performed in the device, the device comprising: A slitting device, the slitting device comprising a pressing roller, and the slitting device is used to slit the battery pole pieces after rolling; A coating device is located on both sides of the pressure roller of the slitting device and is used to output a deburring agent to coat the edge side of the slit electrode.

9. The device according to claim 8, characterized in that The coating device comprises a spraying device; Preferably, the ratio of the slitting speed of the slitting device to the spraying speed of the spraying device is (0.8-1.2):(0.8-1.2).

10. The device according to claim 8 or 8, characterized in that The device further comprises an adjusting device, and the coating device is arranged on the adjusting device so that the edge position of the pole piece when the coating device is cutting relative to the cutting device can be adjusted.

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