Battery pole piece insulation paste as well as preparation method and application thereof

Abstract

The invention discloses a battery pole piece insulation paste which is used for being coated on the surface of a current collector of a battery pole piece, and the insulation paste comprises polyimide and an organic solvent for dissolving the polyimide. By adopting the technical scheme, on one hand, the insulation paste can form a reliable barrier to prevent metal burrs from puncturing a diaphragm, so that the problems of short circuit and thermal runaway of the battery are avoided; and on the other hand, compared with the ceramic slurry which needs to adopt a complex internal coating process, the insulating glue provided by the invention can adopt an external coating process, so that the process is easier to implement, the production difficulty is greatly reduced, the production efficiency is improved, and the problems of mutual dissolution and material mixing with the active slurry can be effectively avoided. The invention also provides a method for preparing the insulation paste for the battery pole piece. The method comprises the following steps: dissolving polyimide in an organic solvent, and stirring to obtain the insulation paste. The invention also discloses an application of the battery pole piece insulation paste in coating.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to a battery electrode sheet insulating glue, a preparation method thereof, and an application thereof. Background Art

[0002] In the actual production process, problems such as burrs, metal particles, and molten beads are likely to occur at the tab end during the laser cutting process. Once these burrs or metal foreign objects penetrate the separator, it may cause the positive and negative electrodes to come into direct contact, thereby triggering a battery short circuit. Seriously, it may even directly lead to thermal runaway of the battery during use. To solve this problem, in the coating process of the battery electrode sheet, an insulating layer is usually coated on the edge of the current collector surface (i.e., the tab end) to cover the exposed metal foil, so as to prevent the burrs generated during tab cutting from causing contact short circuit between the positive and negative electrode sheets.

[0003] The prior art often uses boehmite as the main powder material and polyvinylidene fluoride (PVDF) as the binder to prepare a ceramic slurry. Then it is coated on the edge of the current collector to cover the exposed metal foil. On the one hand, it can reduce the generation of burrs during the laser cutting process; on the other hand, even if slight burrs are generated, the ceramic slurry can play a barrier role to prevent these metal burrs from piercing the separator, thereby avoiding direct contact between the positive and negative metal foils, further avoiding the occurrence of short circuit phenomena, and ensuring that the battery will not cause thermal runaway problems due to short circuit during use.

[0004] However, the coating process of the ceramic slurry (such as the need to use an internal coating process) has extremely strict requirements. During the coating process, the operation must be highly precise and careful to ensure the uniformity and integrity of the coating. Any slight negligence may lead to defects in the coating, such as the mutual dissolution and cross-flow phenomena of the above two slurries, and the mutual dissolution area is usually large. This will not only affect the performance of the battery, such as reducing the electrochemical performance and cycle stability, but also may require re-coating, increasing the production difficulty and time cost. Summary of the Invention

[0005] The present invention provides the following technical solutions to solve the above technical problems.

[0006] The present invention provides a battery electrode sheet insulating glue for coating on the surface of the current collector of the battery electrode sheet, and the insulating glue comprises polyimide and an organic solvent for dissolving polyimide.

[0007] With the above technical solution, on the one hand, based on the excellent insulation performance of polyimide, it can effectively cover the exposed metal foil at the edge of the electrode sheet, form a reliable barrier, prevent metal burrs from piercing the separator, and thus avoid battery short circuit and thermal runaway problems. On the other hand, compared with the ceramic slurry that requires a complex built-in coating process, the insulating adhesive provided by the present invention can adopt an external coating process, which is easier to implement. It not only greatly reduces the production difficulty and improves the production efficiency, but also effectively avoids the problems of mutual dissolution and material leakage between the insulating adhesive and the active slurry.

[0008] Optionally, the mass percentage of polyimide in the insulating adhesive is 5% - 8%.

[0009] Optionally, the insulating adhesive further includes insulating carbon black, and the mass percentage of insulating carbon black in the insulating adhesive is 0.1% - 0.5%.

[0010] Optionally, the solid content of the insulating adhesive is 5% - 7%, where the solid content of the insulating adhesive = the sum of the masses of insulating carbon black and polyimide / the mass of the insulating adhesive.

[0011] Optionally, the viscosity of the insulating adhesive is 500 - 2000 mPa·s.

[0012] Optionally, the organic solvent includes N-methylpyrrolidone, and the mass percentage of N-methylpyrrolidone in the insulating adhesive is 90% - 95%.

[0013] The present invention also provides a method for preparing the battery electrode sheet insulating adhesive in any of the above embodiments, and the method includes:

[0014] Preparing the insulating adhesive: Dissolving polyimide in an organic solvent and stirring to obtain the insulating adhesive.

[0015] With the above technical solution, a battery electrode sheet insulating adhesive with excellent insulation performance and no mutual dissolution or material leakage with the active slurry can be quickly prepared.

[0016] Optionally, in the step of preparing the insulating adhesive, the self-rotation speed of stirring is 800 - 1000 rmp, the revolution speed is 10 - 20 rpm, and the stirring time is 15 - 30 min.

[0017] Optionally, after the step of preparing the insulating adhesive, it further includes:

[0018] Defoaming: Defoaming the insulating adhesive under vacuum conditions to remove the bubbles in the insulating adhesive.

[0019] Optionally, the defoaming step includes: Vacuumizing the insulating adhesive at a vacuum degree of -0.090 MPa ≤ vacuum degree ≤ -0.080 MPa for 30 - 45 min to remove the bubbles in the insulating adhesive.

[0020] The present invention also provides an application of the battery electrode sheet insulating adhesive in coating. Preferably, the coating method is external coating.

[0021] By adopting the above technical solution, the insulating adhesive can be quickly coated on the current collector, greatly simplifying the operation process. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The flowchart showing the preparation method of the battery electrode sheet insulating adhesive in an embodiment of the present invention is shown. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with the preferred embodiments, this does not mean that the features of this invention are limited to this implementation manner. On the contrary, the purpose of introducing the invention in conjunction with the implementation manner is to cover other alternatives or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention can also be implemented without these details. In addition, in order to avoid confusing or obscuring the key points of the present invention, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0024] The terms "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0025] It should be noted that in this specification, similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0026] To make the purpose, technical solution and advantages of the present invention clearer, the implementation manners of the present invention will be further described in detail below with reference to the drawings.

[0027] The present invention provides a battery electrode sheet insulating adhesive for coating on the surface of the current collector of the battery electrode sheet. The insulating adhesive includes polyimide and an organic solvent for dissolving polyimide. Among them, polyimide (abbreviated as PI adhesive), a high-performance polymer material, has excellent high-temperature resistance, mechanical strength and insulation.

[0028] Compared with traditional ceramic slurries, the present invention abandons ceramic materials and binders (such as boehmite and PVDF) and adopts polyimide, a high-performance polymer material, as the main component of the insulating glue. On the one hand, based on the excellent insulating properties of polyimide, it can effectively cover the exposed metal foil at the edge of the pole piece, forming a reliable barrier to prevent metal burrs from piercing the diaphragm, thereby avoiding battery short circuit and thermal runaway problems. On the other hand, compared with the complex built-in coating process required for ceramic slurries, the insulating glue provided by the present invention can adopt an external coating process, which is easier to implement, not only greatly reducing the production difficulty and improving production efficiency, but also effectively avoiding the problems of mutual dissolution and material cross-flow with active slurry. Among them, the built-in coating process refers to the ceramic slurry flowing into the coating die (such as a slit extrusion coater) along the feed inlet, and then coating it on the current collector through the ceramic flow channel designed by the coating gasket, thereby completing the ceramic coating. The external coating is to directly use an external dispensing device to coat the insulating glue provided by the present invention on the current collector without passing through the coating die. The coating method is simple and convenient.

[0029] Furthermore, in the above embodiment, the mass percentage of polyimide to the mass percentage of the insulating glue is 5% to 8%. Controlling the mass percentage of polyimide within the above range can ensure that the viscosity of the insulating glue is in an appropriate range, thereby avoiding the problem of joint and wire drawing during cutting due to excessive viscosity. At the same time, it can also ensure that the insulating glue has a good insulating effect and ensure that the battery can remain stable in a high temperature environment, thereby improving the safety performance and cycle life of the battery. Preferably, the mass percentage of polyimide to the mass percentage of the insulating glue is 5.87%.

[0030] Furthermore, the insulating adhesive also includes insulating carbon black, and the mass percentage of the insulating carbon black in the insulating adhesive is 0.1% - 0.5%. Insulating carbon black is a carbon black material with excellent insulating properties. It is a high-purity, high-density carbon compound obtained through the thermal cracking or incomplete combustion process of hydrocarbon raw materials under specific process conditions. Compared with ordinary carbon black (such as acetylene carbon black), insulating carbon black has significant advantages in terms of conductivity, dielectric loss, insulation impedance, and thermal stability. Adding insulating carbon black to the insulating adhesive can effectively improve the insulation effect of the insulating adhesive. Research has found that adding 0.1% - 0.5% of insulating carbon black can not only significantly improve the insulation performance of the insulating adhesive, but also improve the strength and toughness of the insulating adhesive, enhance its mechanical strength, thereby reducing the material dropping and wire drawing phenomena during the cutting process. In addition, adding insulating carbon black with a mass percentage of 0.1% - 0.5% makes the viscosity of the insulating adhesive more stable, facilitating subsequent coating operations, improving the coating efficiency and quality, and also being beneficial to the smooth progress of the cutting process. This not only greatly improves the production efficiency, but also further improves the quality and safety of the battery. Preferably, the mass percentage of the insulating carbon black in the insulating adhesive is 0.1 - 0.2%. More preferably, the mass percentage of the insulating carbon black in the insulating adhesive is 0.13%.

[0031] Furthermore, in the above-mentioned embodiment, the solid content of the insulating adhesive is 5% - 7%. Among them, the solid content of the insulating adhesive = the sum of the masses of the insulating carbon black and polyimide / the mass of the insulating adhesive. That is, the solid content of the insulating adhesive = (the mass of the insulating carbon black + the mass of the polyimide) / the total mass of the insulating adhesive. Controlling the solid content within the above range can, on the one hand, ensure the concentration of the active components (such as insulating carbon black and polyimide) in the insulating adhesive, thereby ensuring the insulation performance of the insulating adhesive. On the other hand, controlling the solid content within the range of 5% - 7% can maximize the energy density of the battery while ensuring the insulation performance. Specifically, a lower solid content makes the insulating adhesive lighter in weight, thus reducing the impact on the overall weight of the battery. If the solid content is too high, the weight of the insulating adhesive increases, which may lead to a decrease in the coating amount of the active slurry, and thus reduce the energy density of the battery. Therefore, controlling the solid content within the range of 5% - 7% can maximize the energy density of the battery while ensuring the insulation performance.

[0032] Furthermore, in the above-mentioned embodiment, the viscosity of the insulating adhesive is 500 - 2000 mPa·s (millipascal·seconds). Compared with the ceramic slurry (usually with a relatively high viscosity) used in the prior art, the insulating adhesive provided by the present invention has a moderate viscosity, which can not only provide a stable bonding force to ensure a firm bond between the insulating adhesive and the electrode sheet, but also effectively avoid the cutting wire drawing problem caused by too high viscosity. Preferably, the viscosity of the insulating adhesive is 500 - 1300 mPa·s.

[0033] Further, in the above embodiments, the organic solvent includes N-methylpyrrolidone (NMP), wherein the mass percentage of N-methylpyrrolidone in the insulating adhesive is 90%-95%. NMP can better dissolve polyimide and significantly improve its dissolution rate. In addition, NMP also has characteristics such as moderate volatility and good environmental friendliness, and can quickly volatilize after coating, reducing the impact on subsequent processes. Preferably, the mass percentage of N-methylpyrrolidone in the insulating adhesive is 93%-95%. More preferably, the mass percentage of N-methylpyrrolidone in the insulating adhesive is 94%.

[0034] The present invention also provides a method for preparing the battery electrode insulating adhesive in any of the above embodiments, and the method includes:

[0035] Preparing the insulating adhesive: Dissolving polyimide in an organic solvent and stirring to obtain the insulating adhesive.

[0036] By adopting the above technical solution, a battery electrode insulating adhesive with excellent insulating performance and without mutual dissolution or material leakage with the active slurry can be quickly prepared.

[0037] Further, in the above embodiments, in the step of preparing the insulating adhesive, the self-rotation speed of stirring is 800-1000 rmp, the revolution speed is 10-20 rpm, and the stirring time is 15-30 min. Such settings can not only ensure sufficient shear force to fully dissolve polyimide in the organic solvent and avoid agglomeration, but also ensure the formation of a stable insulating adhesive and avoid stratification or precipitation during subsequent coating.

[0038] Further, in the above embodiments, after the step of preparing the insulating adhesive, it further includes:

[0039] Defoaming: Defoaming the insulating adhesive under vacuum conditions to remove the bubbles in the insulating adhesive. On the one hand, the defoaming treatment can effectively remove the bubbles in the insulating adhesive, ensure the uniformity of the composition of the insulating adhesive, and avoid local performance differences caused by bubbles. On the other hand, after removing the bubbles, the fluidity of the insulating adhesive is more stable, and a uniform and complete coating can be formed during coating, reducing coating defects (such as pinholes, cracks, etc.) and ensuring that the insulating performance of the insulating adhesive reaches the best state. On the other hand, the bubbles will reduce the mechanical strength of the insulating adhesive, and the defoaming treatment can improve the density of the insulating adhesive, enhance its mechanical strength and toughness, thereby reducing the problem of material dropping and wire drawing during cutting.

[0040] Further, in the above embodiments, the defoaming step includes: Vacuumizing the insulating adhesive for 30-45 min under the condition of -0.090 MPa ≤ vacuum degree ≤ -0.080 MPa to remove the bubbles in the insulating adhesive. The defoaming effect is the best under this condition, which can effectively remove the bubbles in the insulating adhesive, ensure its uniformity and stability, and thus improve the coating quality and insulating performance.

[0041] The present invention also provides an application of a battery electrode insulating glue in coating. Preferably, the coating method is external coating.

[0042] By adopting the above technical solution, the insulating glue can be quickly coated on the current collector, greatly simplifying the operation process.

[0043] The following is a further detailed description of the present invention through specific embodiments in combination with Figure 1 the present invention.

[0044] Example 1

[0045] Prepare the insulating glue: By mass percentage, the insulating carbon black is 0.13% (purchased from Cabot Corporation), the solvent NMP is 94%, and the PI (polyimide) powder is 5.87%. Weigh 100 g of the above components according to the above ratio. Then, add 50% of the total mass of the NMP solvent and PI powder to the stirring tank, and stir and disperse at a self-rotation speed of 800 rmp and a revolution speed of 12 rpm for 15 minutes to obtain a uniform insulating glue.

[0046] Add the remaining PI powder (50% of the total mass of the PI powder) to the obtained insulating glue, and then stir at a self-rotation speed of 1200 rmp (the preferred range of the self-rotation speed is 1000 - 1200 rmp, and in this embodiment it is 1200 rpm) and a revolution speed of 12 rpm (the preferred range of the revolution speed is 10 - 20 rpm, and in this embodiment it is 12 rpm) for 90 minutes (the preferred range of the stirring time is 60 - 90 minutes, and in this embodiment it is 90 minutes).

[0047] Then add the insulating carbon black to the insulating glue, and stir and disperse at a self-rotation speed of 800 rmp (the preferred range of the self-rotation speed is 800 - 1000 rmp, and in this embodiment it is 800 rpm) and a revolution speed of 12 rpm (the preferred range of the revolution speed is 10 - 20 rpm, and in this embodiment it is 12 rpm) for 30 minutes (the preferred range of the stirring time is 30 - 45 minutes, and in this embodiment it is 30 minutes);

[0048] Defoaming: Defoam the insulating glue under vacuum conditions to remove the bubbles in the insulating glue. Among them, the self-rotation speed of stirring during the defoaming process is 600 rmp (the preferred range of the self-rotation speed is selected from 300 - 600 rpm, and in this embodiment it is 600 rpm), the vacuum degree is -90 MPa, and the vacuum pumping time is 30 minutes. The solid content of the battery electrode insulating glue prepared in this embodiment is 6%, and the viscosity is 800 mPa·s. Among them, the viscometer used for viscosity detection is purchased from Fungilab Company, the model of the viscometer is SmartL, the rotor of the viscometer adopts the L3 rotor, and the rotation speed is 30 revolutions per minute.

[0049] Example 2

[0050] Prepare insulating glue: By mass percentage, insulating carbon black is 0.15%, solvent NMP is 93%, and PI (polyimide) powder is 6.85%. Weigh 100 g of the above components according to the above ratio. Then add 50% of the total mass of NMP solvent and PI powder into the stirring tank, and stir and disperse at a self-rotation speed of 900 rmp and a revolution speed of 12 rpm for 15 minutes to obtain a uniform insulating glue.

[0051] Add the remaining PI powder (50% of the total mass of PI powder) to the obtained insulating glue, and then stir at a self-rotation speed of 1000 rmp and a revolution speed of 15 rpm for 120 minutes.

[0052] Add insulating carbon black to the insulating glue again, and stir and disperse at a self-rotation speed of 900 rmp and a revolution speed of 12 rpm for 30 minutes;

[0053] Defoaming: Defoam the insulating glue under vacuum conditions to remove the bubbles in the insulating glue. Among them, the dispersion speed during defoaming is 300 rmp, the vacuum degree is -90 MPa, and the vacuum pumping time is 30 minutes. The solid content of the battery electrode insulating glue prepared in this example is 6%, and the viscosity is 1000 mPa·s. Among them, the viscometer used for viscosity detection was purchased from Fungilab Company, the model of the viscometer is SmartL, the rotor of the viscometer adopts L3 rotor, and the rotation speed is 30 revolutions / minute.

[0054] Example 3

[0055] Prepare insulating glue: By mass percentage, insulating carbon black is 0.2%, solvent NMP is 92.8%, and PI (polyimide) powder is 7%. Weigh the above components according to the above ratio. Then add 50% of the total mass of NMP solvent and PI powder into the stirring tank, and stir and disperse at a self-rotation speed of 800 rmp and a revolution speed of 12 rpm for 15 minutes to obtain a uniform insulating glue.

[0056] Add the remaining PI powder (50% of the total mass of PI powder) to the obtained insulating glue, and then stir at a self-rotation speed of 1200 rmp and a revolution speed of 20 rpm for 150 minutes.

[0057] Add insulating carbon black to the insulating glue again, and stir and disperse at a self-rotation speed of 1000 rmp and a revolution speed of 12 rpm for 30 minutes;

[0058] Defoaming: Defoam the insulating glue under vacuum conditions to remove the air bubbles in the insulating glue. Among them, the dispersion speed during defoaming is 300 rmp, the vacuum degree is -90 MPa, and the vacuum pumping time is 30 min. The solid content of the battery electrode insulating glue prepared in this example is 6%, and the viscosity is 1250 mPa·s. Among them, the viscometer used for viscosity detection was purchased from Fungilab Company, the model of the viscometer is SmartL, the rotor of the viscometer adopts the L3 rotor, and the rotation speed is 30 revolutions / min.

[0059] Example 4

[0060] Preparation of insulating glue: By mass percentage, insulating carbon black is 0.1%, solvent NMP is 89.9%, and PI (polyimide) powder is 10%. Weigh the above components according to the above ratio. Then add 50% of the total mass of NMP solvent and PI powder to the stirring tank, and stir and disperse at a self-rotation speed of 800 rmp and a revolution speed of 12 rpm for 15 min to obtain a uniform insulating glue.

[0061] Add the remaining PI powder to the obtained insulating glue, and then stir at a self-rotation speed of 1200 rmp and a revolution speed of 20 rpm for 150 min.

[0062] Add insulating carbon black to the insulating glue again, and stir and disperse at a self-rotation speed of 1000 rmp and a revolution speed of 12 rpm for 30 min;

[0063] Defoaming: Defoam the insulating glue under vacuum conditions to remove the air bubbles in the insulating glue. Among them, the dispersion speed during defoaming is 300 rmp, the vacuum degree is -90 MPa, and the vacuum pumping time is 30 min. The solid content of the battery electrode insulating glue prepared in this example is 6%, and the viscosity is 1500 mPa·s. Among them, the viscometer used for viscosity detection was purchased from Fungilab Company, the model of the viscometer is SmartL, the rotor of the viscometer adopts the L3 rotor, and the rotation speed is 30 revolutions / min.

[0064] Example 5

[0065] Preparation of insulating glue: By mass percentage, insulating carbon black is 0.3%, solvent NMP is 87.7%, and PI (polyimide) powder is 12%. Weigh the above components according to the above ratio. Then add the NMP solvent and PI powder to the stirring tank, and stir and disperse at a self-rotation speed of 900 rmp and a revolution speed of 15 rpm for 15 min to obtain a uniform insulating glue.

[0066] Add the remaining PI powder to the obtained insulating glue, and then stir at a self-rotation speed of 1100 rmp and a revolution speed of 20 rpm for 150 min.

[0067] Add insulating carbon black to the insulating glue, and stir and disperse it at a self-rotation speed of 900 rmp and a revolution speed of 12 rpm for 30 minutes.

[0068] Defoaming: Defoam the insulating glue under vacuum conditions to remove the bubbles in the insulating glue. Among them, the dispersion speed during defoaming is 300 rmp, the vacuum degree is -90 MPa, and the vacuum pumping time is 30 minutes. The solid content of the battery electrode insulating glue prepared in this example is 6%, and the viscosity is 1850 mPa·s. Among them, the viscometer used for viscosity detection was purchased from Fungilab Company, the model of the viscometer is SmartL, the rotor of the viscometer adopts the L3 rotor, and the rotation speed is 30 revolutions per minute.

[0069] Example 6

[0070] Prepare insulating glue: By mass percentage, insulating carbon black is 0.6%, solvent NMP is 84.4%, and PI (polyimide) powder is 15%. Weigh the above components according to the above ratio. Then add the NMP solvent and PI powder into the stirring tank, and stir and disperse them at a self-rotation speed of 800 rmp and a revolution speed of 15 rpm for 15 minutes to obtain a uniform insulating glue.

[0071] Add the remaining PI powder to the obtained insulating glue, and then stir at a self-rotation speed of 1000 rmp and a revolution speed of 20 rpm for 150 minutes.

[0072] Add insulating carbon black to the insulating glue, and stir and disperse it at a self-rotation speed of 900 rmp and a revolution speed of 12 rpm for 30 minutes.

[0073] Defoaming: Defoam the insulating glue under vacuum conditions to remove the bubbles in the insulating glue. Among them, the dispersion speed during defoaming is 300 rmp, the vacuum degree is -90 MPa, and the vacuum pumping time is 30 minutes. The solid content of the battery electrode insulating glue prepared in this example is 6.6%, and the viscosity is 2050 mPa·s. Among them, the viscometer used for viscosity detection was purchased from Fungilab Company, the model of the viscometer is SmartL, the rotor of the viscometer adopts the L3 rotor, and the rotation speed is 30 revolutions per minute.

[0074] The positive electrode active slurry is coated on the surface of the current collector, and then the insulating glue in the above embodiment 1 is coated on one side of the positive electrode active slurry, the situation after coating is observed, and the results are recorded in Table 1; the positive electrode active slurry is coated on the surface of the current collector, and then the insulating glue in the above embodiment 2 is coated on one side of the positive electrode active slurry, the situation after coating is observed, and the results are recorded in Table 1. Repeat the above operation for the remaining embodiments. Then, the electrode tabs coated with the insulating glue are laser cut, and whether there is wire drawing or jointing during the cutting process is also recorded in Table 1; after the cutting is completed, observe whether the cut interface contains burrs or molten beads, and the results are also recorded in Table 1.

[0075] Table 1

[0076]

[0077]

[0078] It can be seen from Table 1 that the insulating adhesives provided in Examples 1-6 of the present invention can effectively avoid the problems of mutual dissolution and material cross-contamination with the active slurry.

[0079] Furthermore, in Examples 1-3, the mass percentage of polyimide is controlled within the range of 5% to 8%, and the viscosity is within the range of 500-1300 mPa·s, thereby effectively avoiding the problems of stringing and wire drawing during cutting due to excessively high viscosity.

[0080] Although the present invention has been illustrated and described with reference to certain preferred embodiments of the present invention, it should be understood by those skilled in the art that the above is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. Those skilled in the art may make various changes in form and details, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A battery pole piece insulating adhesive, used for coating on the current collector surface of the battery pole piece, characterized in that: The insulating adhesive comprises polyimide and an organic solvent for dissolving the polyimide.

2. The battery pole piece insulating adhesive according to claim 1, characterized in that: The mass percentage of the polyimide to the mass percentage of the insulating glue is 5% to 8%.

3. The battery pole piece insulating adhesive according to claim 1, characterized in that: The insulating adhesive further comprises insulating carbon black, and the mass percentage of the insulating carbon black to the mass percentage of the insulating adhesive is 0.1% to 0.5%.

4. The battery pole piece insulating adhesive according to claim 3, characterized in that: The solid content of the insulating adhesive is 5%-7%, wherein the solid content of the insulating adhesive = the sum of the masses of insulating carbon black and polyimide / the mass of the insulating adhesive.

5. The battery pole piece insulating adhesive according to claim 1, characterized in that: The viscosity of the insulating glue is 500-2000 mPa·s.

6. The battery pole piece insulating adhesive according to any one of claims 1 to 5, characterized in that: The organic solvent comprises N-methylpyrrolidone, wherein the mass percentage of the N-methylpyrrolidone in the insulating glue is 90%-95%.

7. A method for preparing the battery pole piece insulating adhesive according to any one of claims 1 to 6, characterized in that: include: Preparation of insulating adhesive: dissolving the polyimide in the organic solvent and stirring to obtain the insulating adhesive.

8. The method for preparing the battery pole piece insulating adhesive according to claim 7, characterized in that: In the step of preparing the insulating adhesive, the stirring rotation speed is 800-1000 rpm, the revolution speed is 10-20 rpm, and the stirring time is 15-30 min.

9. The method for preparing the battery pole piece insulating adhesive according to claim 8, characterized in that: The step of preparing the insulating adhesive further comprises: Degassing: degassing the insulating adhesive under vacuum conditions to remove bubbles in the insulating adhesive.

10. The method for preparing the battery pole piece insulating adhesive according to claim 9, characterized in that: The degassing step comprises: vacuumizing the insulating glue for 30 to 45 minutes under the condition of -0.090 MPa ≤ vacuum degree ≤ -0.080 MPa to remove bubbles in the insulating glue.

11. Use of the battery pole piece insulating adhesive according to any one of claims 1 to 5 in coating, preferably, the coating method is external coating.

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