Positive electrode edge coating adhesive, preparation method, positive electrode sheet and bonding method

Abstract

Disclosed in the present invention are a positive electrode edge coating adhesive, a preparation method, a positive electrode sheet and a bonding method. The present invention aims to provide a positive electrode edge coating adhesive having high adhesion, high thixotropy, no bleeding during coating, and good electrolyte resistance. According to the technical solution thereof, the positive electrode edge coating adhesive is prepared by copolymerizing a hard monomer, a soft monomer, a first functional monomer, a second functional monomer, a crosslinking monomer, a tackifying resin, an initiator and a solvent, with the components totalling 100%. Further disclosed in the present invention are a positive electrode sheet in which the positive electrode edge coating adhesive is used, and a method for bonding the positive electrode sheet that has been coated with the positive electrode edge coating adhesive with a PP separator. The positive electrode sheet coated with the adhesive is of good quality, and the electrode sheet or a formed coating is prevented from the phenomena of peeling off, cracking, etc., after being folded in half on both the front and back sides. Moreover, the positive electrode sheet and the PP separator are firmly bonded, and the phenomenon of cracking or peeling off does not occur after soaking in an electrolyte for a long time. The present invention belongs to the technical field of polymers.

Description

A positive electrode edge coating adhesive, preparation method, positive electrode sheet and bonding method

[0001] This application claims priority to Chinese Patent Application No. 202411742776.0, filed on November 29, 2024, entitled "A Positive Electrode Edge Coating Adhesive, Preparation Method, Positive Electrode Sheet and Bonding Method", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to the field of polymer materials technology, specifically to a positive electrode edge coating adhesive and its preparation method, a positive electrode sheet containing the edge coating adhesive, and a method for bonding the positive electrode sheet to a polypropylene (PP) separator. Background Technology

[0003] With the rapid development of electric vehicles and renewable energy, lithium-ion batteries, as a highly efficient and reliable energy storage device, have enormous market potential. The positive electrode is a crucial component of a lithium battery, responsible for the insertion and extraction of lithium ions. However, the edge areas of the positive electrode are prone to expansion, and burrs and misalignment can occur during electrode cutting, leading to decreased battery performance or internal short circuits.

[0004] To address these issues, CATL pioneered the use of edge-coating adhesives applied to the edges of the positive electrode to enhance structural stability and battery safety. Polyvinylidene fluoride (PVDF) is the mainstream material used for edge coating adhesives on the market, but its poor adhesion makes it prone to detachment after electrolyte immersion, failing to secure the separator to the electrode position. Furthermore, uneven distribution and incomplete edge coverage during high-speed coating can lead to weak edges or material cross-contamination, thus affecting the safety and cycle stability of lithium-ion batteries. Currently, several new edge-coating adhesive systems have emerged, such as ethylene-acrylic acid copolymer (EAA), polyimide (PI), polyamide (PA), and polyacrylate. Among these, polyacrylate stands out due to its excellent adhesion, low raw material cost, diverse modification methods, and simple production process. Polyacrylate also has adhesive properties and can be used as pressure-sensitive and heat-sensitive adhesives, widely used in consumer goods and electronic products. However, when ordinary polyacrylate adhesives are used for edge coating protection of lithium battery positive electrodes, the following problems exist:

[0005] 1. During the electrode coating stage, the slurry for coating the positive electrode edge is applied to the electrode from the mixing tank using a dispensing machine. The slurry's state undergoes a change from high shear to near-static. Ordinary polyacrylate binders have low thixotropy, resulting in minimal viscosity changes regardless of high or low shear rates. Low-viscosity polyacrylate binder slurries, even in a wet film state on the electrode, are prone to flow and cross-contamination, leading to overlap problems. High-viscosity polyacrylate binders easily clog pipelines and filter cartridges during processing, making coating impossible.

[0006] 2. Ordinary polyacrylate adhesives have many internal polar groups (such as hydroxyl and carboxyl groups), which make them good at bonding with metals, but poor at bonding with non-polar lithium battery PP separators. After being immersed in electrolyte, the coating cannot simultaneously satisfy the requirement of firmly bonding the lithium battery PP separator and aluminum foil.

[0007] Therefore, it is crucial to develop a positive electrode edge coating adhesive that has high adhesion, high thixotropy, and good electrolyte resistance to lithium battery PP separators. Summary of the Invention

[0008] In view of the shortcomings and deficiencies of the existing technology, the purpose of this invention is to provide a positive electrode edge coating adhesive with high adhesion, high thixotropy, no material cross-contamination during coating, and good electrolyte resistance.

[0009] A second objective of this invention is to provide a method for preparing the above-mentioned positive electrode edge coating adhesive.

[0010] The third objective of this invention is to provide a positive electrode sheet with an edge-coated adhesive, which has excellent quality and will not peel off or crack after being folded in both directions.

[0011] The fourth objective of this invention is to provide a bonding method for the positive electrode sheet and the PP separator. This bonding method is simple, the positive electrode sheet and the PP separator are firmly bonded, and there will be no cracking or detachment when immersed in electrolyte for a long time.

[0012] Therefore, the first technical solution provided by this invention is as follows:

[0013] A positive electrode edge coating adhesive is prepared by copolymerization of the following raw materials in the indicated mass percentages:

[0014] The sum of all components is 100%.

[0015] Furthermore, the mass ratio of the hard monomer to the soft monomer is 4:3 to 4:10.

[0016] In this case, the higher the content of soft monomers, the better the flexibility, but the worse the electrolyte resistance; the higher the content of hard monomers, the harder the electrode, which is easy to crack when folded, but the better the electrolyte resistance. When the mass ratio of hard monomers to soft monomers is 4:3 to 4:10, both flexibility and electrolyte resistance can be achieved at the same time.

[0017] In this case, the amount of initiator used ensures complete reaction, meets viscosity requirements, and is resistant to electrolyte. If the initiator content is too low, the reaction will be incomplete, resulting in low viscosity of the final product and poor resistance to electrolyte. If the initiator content is too high, the reaction will be excessive, resulting in low viscosity of the final product and poor resistance to electrolyte.

[0018] In this case, the amount of crosslinking monomer used was balanced to ensure that the viscosity met the standard, resulting in high thixotropy and making the electrode less prone to brittleness. Conversely, if the crosslinking monomer content was too low, the final product would have insufficient viscosity and low thixotropy; if it was too high, the final product would have high viscosity and the electrode would be prone to brittleness.

[0019] In this case, the amount of tackifying resin used needs to balance high peel strength and resistance to electrolyte immersion. If the tackifying resin content is too low, the final product will have low peel strength; if the content is too high, it will not be resistant to electrolyte immersion.

[0020] Preferably, in the above-mentioned positive electrode edge coating adhesive, the hard monomer is composed of styrene and auxiliary hard monomers; the auxiliary hard monomer is one or more of acrylonitrile, methyl acrylate, and methyl methacrylate.

[0021] In this case, the hard monomer is styrene or styrene combined with one or more other auxiliary hard monomers, and the mass of styrene is not less than the sum of the masses of the auxiliary hard monomers to ensure that there is no material cross-contamination during the overlap.

[0022] Furthermore, the aforementioned positive electrode edge coating adhesive is characterized in that the soft monomer is one or more of butyl acrylate, isooctyl acrylate, lauryl acrylate, butyl methacrylate, isooctyl methacrylate, isobornyl acrylate, and lauryl methacrylate.

[0023] Preferably, in the above-mentioned positive electrode edge coating adhesive, the first functional monomer is at least one of acrylic acid or methacrylic acid; and the second functional monomer is at least one of N-methacrylamide or N-vinylpyrrolidone.

[0024] More preferably, in the above-mentioned positive electrode edge coating adhesive, the second functional monomer further includes one or any combination of hydroxypropyl acrylate, hydroxybutyl acrylate, and hydroxyethyl acrylate.

[0025] In this case, the dosage of the first functional monomer ensures complete monomer reaction, meets the viscosity standard of the prepared colloid, prevents material cross-contamination, and ensures resistance to electrolyte immersion. If the acrylic acid content is higher, the viscosity will be greater, and excessive viscosity will cause material cross-contamination during coating. If the acrylic acid content is too low, the colloid viscosity will be low. The higher the content of the second functional monomer, acrylamide, the better the electrolyte resistance, but excessive content will cause material cross-contamination. If the content of acrylamide is too low, the electrode will have poor electrolyte resistance after coating.

[0026] In this case, the higher the content of acrylamide monomers, the better the electrolyte resistance; the role of hydroxy acrylate monomers further enhances the electrolyte resistance.

[0027] Preferably, in the above-mentioned positive electrode edge coating adhesive, the crosslinking monomer is one or any mixture of divinylbenzene and glycidyl methacrylate.

[0028] In this case, the use of divinylbenzene and glycidyl methacrylate as crosslinking monomers is beneficial for increasing the viscosity and thixotropy of the product.

[0029] Preferably, the tackifying resin in the above-mentioned positive electrode edge coating adhesive is one or any mixture of terpene resin and rosin resin.

[0030] In this case, the use of terpene resin and rosin resin is beneficial to increasing the adhesion of the product.

[0031] Preferably, in the above-mentioned positive electrode edge coating adhesive, the initiator is one or more of benzoyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile.

[0032] Preferably, the solvent for the above-mentioned positive electrode edge coating adhesive is N-methylpyrrolidone.

[0033] The second technical solution provided by this invention is a method for preparing the positive electrode edge coating adhesive as described in the first technical solution, which includes the following steps in sequence:

[0034] 1) Weigh each component according to the following mass percentages;

[0035] The sum of all components is 100%.

[0036] 2) After stirring the hard monomer, the first functional monomer, 35wt%-45wt% crosslinking monomer and 30wt%-40wt% solvent weighed in step 1) evenly, heat to 65-85℃, and then add some initiator to react for 1-2 hours to obtain solution (1).

[0037] 3) Add the soft monomer, the second functional monomer, the remaining crosslinking monomer, the tackifying resin and the remaining initiator to the remaining solvent to obtain a mixed solution. Add the mixed solution to solution (1) dropwise and react at 75-95°C for 1-2 hours.

[0038] 4) After the reaction is complete, the material is cooled and discharged to obtain the positive electrode edge coating adhesive.

[0039] The third technical solution of the present invention is to provide a positive electrode sheet, which uses the positive electrode edge coating adhesive described in the first technical solution. The application method is to mix the positive electrode edge coating adhesive described in the first technical solution with boehmite to form a mixed slurry with a refractory-to-solid ratio of 0.1 to 0.8, filter it, coat it on aluminum foil, and dry it to obtain the positive electrode sheet.

[0040] The positive electrode sheet provided in this case is made by mixing the positive electrode edge coating adhesive with boehmite to obtain a mixed slurry, which is then coated on aluminum foil and dried. The manufacturing method is simple, and the prepared positive and negative double-sided electrode sheet or coating will not peel off or crack after folding, and the electrode sheet is of excellent quality.

[0041] The present invention also provides a method for bonding a positive electrode sheet to a PP separator. The method involves covering the positive electrode sheet described in the third technical solution with a lithium battery PP separator, and then hot-pressing the adhesive at 90-110°C.

[0042] The positive electrode sheet and the PP diaphragm are firmly bonded and resistant to electrolyte immersion, and will not crack or fall off.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. This invention provides a technical solution that, through research on the specific types and contents of soft and hard monomers, first functional monomers, second functional monomers, crosslinking monomers, tackifying resins, and initiators, produces products that simultaneously meet the following requirements through monomer free radical polymerization and crosslinking polymerization: peel strength > 0.15 N / cm; viscosity > 30000.00 mPa·s at 1 lead second and > 3000.00 mPa·s at 50 lead seconds; after immersion in electrolyte at 60°C for 7 days, the edge coating adhesive and diaphragm on the electrode sheet are firmly bonded without detachment; the boundary between the positive electrode edge coating slurry and the positive electrode slurry is clear without material cross-contamination; and the electrode sheet does not exhibit brittle cracking or detachment.

[0045] 2. The technical solution provided by this invention employs a reverse free radical polymerization initiated by a certain amount of initiator for soft monomers and functional monomers. The functional monomer acrylic acid provides a weakly acidic environment for the system, and at the same time, it has a strong electron-withdrawing ability and a reduced electron cloud density, which is more conducive to the attack of free radicals and further accelerates the reaction process, thereby increasing the viscosity of the positive electrode edge coating adhesive. The hard monomer and the second functional monomer undergo free radical polymerization initiated by a certain amount of initiator. The hard monomer is a compound of styrene and hard monomer, which improves the thixotropic properties of the product and ensures that the overlap does not cross-contaminate. Acrylamide is used as the main second functional monomer. Through the strong interaction with the metal surface through polar groups such as amide bonds and hydroxyl groups, it is conducive to the adhesion to aluminum foil and enhances the electrolyte immersion resistance of the positive electrode edge coating adhesive. Thus, the final product has good thixotropic properties, prevents cross-contamination, and has good electrolyte resistance.

[0046] 3. The technical solution provided by this invention constructs a cross-linked network after monomer polymerization, and further introduces cross-linked monomers and studies the compatibility of cross-linked monomers with other monomers to effectively adjust the cross-linking density within the molecule, thereby controlling the viscosity and thixotropy of the product, ensuring that the viscosity meets the standard and the thixotropy is high, and ensuring that the coated electrode is not easily brittle; preventing the problem of insufficient viscosity and low thixotropy in the final product; or high viscosity and poor thixotropy.

[0047] 4. This invention provides a technical solution that, by combining soft and hard monomers, alters the flexibility and cohesiveness of the polymerized molecular chains, thereby achieving effective adhesion of the positive electrode edge coating adhesive to the aluminum foil and PP separator. Furthermore, it ensures that the coated electrode sheet remains unchanged when folded and does not crack or detach; and that the positive electrode sheet, after being hot-pressed with the lithium battery PP separator, does not detach after being immersed in electrolyte at 60°C for 7 days; possessing both flexibility and electrolyte resistance performance indicators.

[0048] 5. The technical solution provided in this application incorporates a certain amount of tackifying resin into the molecular backbone, which increases the non-polar units in the molecular structure, significantly improving the adhesion performance with the lithium battery PP separator, and also significantly improving the electrolyte resistance of the product after bonding the lithium battery PP separator.

[0049] 6. The positive electrode sheet prepared by the technical solution provided in this application is of excellent quality. After folding the front and back sides, the electrode sheet or coating will not peel off or crack.

[0050] 7. The bonding method between the positive electrode sheet and the PP separator provided in this application is simple and easy to operate. The adhesive between the positive electrode sheet and the PP separator is firm and will not crack or fall off after long-term immersion in electrolyte. Attached Figure Description

[0051] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0052] Figure 1 is a photograph of the finished product after hot pressing the positive electrode sheet and the battery separator provided in Application Example 1;

[0053] Figure 2 is a photograph of the electrolyte resistance test of the positive electrode sheet of the bonded battery separator provided in Application Example 1.

[0054] Figure 3 is a photograph of the positive electrode edge coating adhesive crosslinking performance test provided in Example 1;

[0055] In the figure, 11. PP membrane, 10. Positive electrode sheet for bonding PP membrane, 20. Electrolyte. Detailed Implementation

[0056] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0057] Example 1

[0058] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0059] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent N-methylpyrrolidone (NMP) to a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0060] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0061] Example 2

[0062] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0063] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0064] (2) 60g of soft monomer isooctyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0065] Example 3

[0066] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0067] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0068] (2) 60g of soft monomer lauryl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0069] Example 4

[0070] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0071] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0072] (2) After stirring 40g of soft monomer butyl acrylate, 20g of soft monomer isooctyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution system (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0073] Example 5

[0074] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0075] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0076] (2) After stirring 40g of soft monomer butyl acrylate, 20g of soft monomer lauryl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0077] Example 6

[0078] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0079] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0080] (2) After stirring 40g of soft monomer isooctyl acrylate, 20g of soft monomer lauryl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0081] Example 7

[0082] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0083] (1) Add 20g of hard monomer styrene, 20g of hard monomer acrylonitrile, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0084] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0085] Example 8

[0086] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0087] (1) Add 20g of hard monomer styrene, 20g of hard monomer methyl acrylate, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0088] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0089] Example 9

[0090] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0091] (1) Add 20g of hard monomer styrene, 20g of hard monomer methyl methacrylate, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP to a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0092] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0093] Example 10

[0094] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0095] (1) 20g of hard monomer styrene, 10g of hard monomer acrylonitrile, 10g of hard monomer methyl acrylate, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP were added to a reaction flask. Under nitrogen protection, the mixture was stirred at 80°C until homogeneous. 0.2g of initiator azobisisobutyronitrile was added. After reacting for 1.5h, 100g of solvent NMP was added to obtain solution (1).

[0096] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0097] Example 11

[0098] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0099] (1) 25g of hard monomer styrene, 5g of hard monomer acrylonitrile, 10g of hard monomer methyl methacrylate, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP were added to a reaction flask. Under nitrogen protection, the mixture was stirred at 80°C until homogeneous. 0.2g of initiator azobisisobutyronitrile was added. After reacting for 1.5h, 100g of solvent NMP was added to obtain solution (1).

[0100] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0101] Example 12

[0102] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0103] (1) Add 40g of hard monomer styrene, 10g of functional monomer methacrylic acid, 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1).

[0104] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0105] Example 13

[0106] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0107] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0108] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 5g of functional monomer hydroxyethyl acrylate, 5g of functional monomer N-vinylpyrrolidone, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0109] Example 14

[0110] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0111] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0112] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxypropyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0113] Example 15

[0114] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0115] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0116] (2) After stirring 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxybutyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0117] Example 16

[0118] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0119] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0120] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 5g of functional monomer hydroxypropyl acrylate, 5g of functional monomer N-vinylpyrrolidone, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0121] Example 17

[0122] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0123] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0124] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer N-vinylpyrrolidone, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0125] Example 18

[0126] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0127] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0128] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 5g of functional monomer hydroxybutyl acrylate, 5g of functional monomer N-vinylpyrrolidone, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0129] Example 19

[0130] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0131] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer divinylbenzene and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0132] (2) After stirring 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer divinylbenzene, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0133] Example 20

[0134] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0135] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0136] (2) After stirring 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer divinylbenzene, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0137] Example 21

[0138] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0139] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0140] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 110g of tackifying resin rosin resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0141] Example 22

[0142] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0143] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 65°C under nitrogen protection, add 0.2g of initiator azobisisoheptanenitrile, continue to react for 2h, and then add 100g of solvent NMP to obtain solution (1);

[0144] (2) After stirring 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, add the mixture dropwise to the solution (1) prepared in step (1) within 2 hours. Continue to add 365g of solvent N-methylpyrrolidone (NMP), react at 75℃ for 4 hours, and then discharge the mixture.

[0145] Example 23

[0146] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0147] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 85°C under nitrogen protection, add 0.2g of initiator benzoyl peroxide, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0148] (2) After stirring 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator benzoyl peroxide in a beaker, add the mixture dropwise to the solution (1) prepared in step (1) within 2 hours. Continue to add 365g of solvent N-methylpyrrolidone (NMP), react at 95℃ for 4 hours, and then discharge the mixture.

[0149] Example 24

[0150] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0151] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0152] (2) 100g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0153] Example 25

[0154] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0155] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0156] (2) After stirring 30g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0157] Example 26

[0158] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0159] (1) Add 40g of hard monomer styrene, 2g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0160] (2) After stirring 60g of soft monomer butyl acrylate, 5g of functional monomer N-methacrylamide, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0161] Example 27

[0162] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0163] (1) Add 40g of hard monomer styrene, 25g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0164] (2) After stirring 60g of soft monomer butyl acrylate, 40g of functional monomer N-methacrylamide, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0165] Example 28

[0166] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0167] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.6g of initiator azobisisobutyronitrile, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0168] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 1.0g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0169] Example 29

[0170] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0171] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.4g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0172] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.6g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0173] Example 30

[0174] This embodiment provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0175] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0176] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 20g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0177] Table 1 summarizes the components and their parameters for Examples 1-30:

[0178] To better utilize the positive electrode edge coating adhesive provided in Embodiments 1-30 of this application, the following are examples of its use in bonding the positive electrode sheet to the separator:

[0179] Application Example 1

[0180] This application example provides a positive electrode sheet, which is prepared by mixing the positive electrode edge coating adhesive provided in Example 1 with boehmite at a folding-to-solid ratio of 0.1 to form a mixed slurry, filtering to obtain a positive electrode edge coating slurry, coating the obtained positive electrode edge coating slurry on aluminum foil, and drying to obtain a positive electrode sheet.

[0181] Application Example 2

[0182] This application example provides a method for bonding the positive electrode sheet prepared in Application Example 1 to the lithium battery PP separator adhesive. The method involves covering the positive electrode sheet prepared in Application Example 1 with the lithium battery PP separator and then hot-pressing it at 100°C to achieve bonding between the battery separator and the positive electrode sheet.

[0183] Application Example 3

[0184] This application example provides a positive electrode sheet, which is prepared by mixing the positive electrode edge coating adhesive provided in Example 2 with boehmite at a folding-to-solid ratio of 0.2 to form a mixed slurry, filtering to obtain a positive electrode edge coating slurry, coating the obtained positive electrode edge coating slurry on aluminum foil, and drying to obtain a positive electrode sheet.

[0185] Application Example 4

[0186] This application example provides a method for bonding the positive electrode sheet prepared in Application Example 3 to the PP separator adhesive of a lithium battery. This method is...

[0187] The lithium battery PP separator is covered on the positive electrode sheet prepared above, and then hot-pressed at 90°C to achieve bonding between the battery separator and the positive electrode sheet.

[0188] Application Example 5

[0189] This application example provides a positive electrode sheet, which is prepared by mixing the positive electrode edge coating adhesive provided in Example 8 with boehmite at a fold-to-solid ratio of 0.5 to form a mixed slurry, filtering to obtain a positive electrode edge coating slurry, coating the obtained positive electrode edge coating slurry on aluminum foil, and drying to obtain a positive electrode sheet.

[0190] Application Example 6

[0191] This application example provides a method for bonding the positive electrode sheet prepared in Application Example 5 to the PP separator adhesive of a lithium battery. This method is...

[0192] The lithium battery PP separator is applied to the positive electrode sheet prepared above, and then hot-pressed at 110°C to achieve bonding between the battery separator and the positive electrode sheet.

[0193] Application Example 7

[0194] This application example provides a positive electrode sheet, which is prepared by mixing the positive electrode edge coating adhesive provided in Example 8 with boehmite at a folding-to-solid ratio of 0.8 to form a mixed slurry, filtering to obtain a positive electrode edge coating slurry, coating the obtained positive electrode edge coating slurry on aluminum foil, and drying to obtain a positive electrode sheet.

[0195] Application Example 8

[0196] This application example provides a method for bonding the positive electrode sheet prepared in Application Example 7 to the PP separator adhesive of a lithium battery. This method is...

[0197] The lithium battery PP separator is covered on the prepared positive electrode sheet, and then hot-pressed at 110°C to fix the battery separator and the electrode sheet, thus achieving the bonding between the battery separator and the positive electrode sheet.

[0198] Application Example 9

[0199] 1) The positive electrode edge coating adhesive provided in Example 17 is mixed with boehmite at a fold-to-solid ratio of 0.2 to form a mixed slurry. The mixture is filtered to obtain a positive electrode edge coating slurry. The obtained positive electrode edge coating slurry is coated on aluminum foil and dried to obtain a positive electrode sheet.

[0200] Application Example 10

[0201] This application example provides a method for bonding the positive electrode sheet prepared in Application Example 9 to the PP separator adhesive of a lithium battery. This method is...

[0202] The lithium battery PP separator is covered on the positive electrode sheet prepared above, and then hot-pressed at 90°C to fix the battery separator and the electrode sheet, thus obtaining a positive electrode sheet with bonded separator.

[0203] Comparative Example 1

[0204] This case provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0205] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent N-methylpyrrolidone to a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0206] (2) Stir 60g of (meth) octadecyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker until homogeneous. Then, add the mixture dropwise to the solution system (1) prepared in step (1) within 2 hours. Continue to add 365g of solvent N-methylpyrrolidone and react at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0207] Comparative Example 2

[0208] This case provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0209] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0210] (2) After stirring 60g of soft monomer butyl acrylate, 20g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0211] Comparative Example 3

[0212] This case provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0213] (1) Add 40g of hard monomer styrene, 10g of functional monomer hydroxyethyl acrylate, 0.3g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue the reaction for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0214] (2) 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.5g of crosslinking monomer glycidyl methacrylate, 11g of tackifying resin terpene resin, and 0.6g of initiator azobisisobutyronitrile are stirred evenly in a beaker and then added dropwise to the solution (1) prepared in step (1) within 2 hours. 365g of solvent N-methylpyrrolidone (NMP) is added, and the reaction is carried out at 90°C for 4 hours. The positive electrode edge coating adhesive is then discharged.

[0215] Comparative Example 4

[0216] This case provides a positive electrode edge coating adhesive, which is prepared through the following raw materials and steps:

[0217] (1) Add 40g of hard monomer styrene, 10g of functional monomer acrylic acid (neutralization degree 90%), 0.1g of crosslinking monomer glycidyl methacrylate and 100g of solvent NMP into a reaction flask, stir evenly at 80°C under nitrogen protection, add 0.2g of initiator azobisisobutyronitrile, continue to react for 1.5h, and then add 100g of solvent NMP to obtain solution (1);

[0218] (2) After stirring 60g of soft monomer butyl acrylate, 10g of functional monomer N-methacrylamide, 10g of functional monomer hydroxyethyl acrylate, 0.3g of crosslinking monomer glycidyl methacrylate, 11g of terpene resin, and 0.6g of initiator azobisisobutyronitrile in a beaker, the mixture was added dropwise to the solution (1) prepared in step (1) within 2 hours. Then, 365g of solvent N-methylpyrrolidone (NMP) was added. The mixture was reacted at 90°C for 4 hours, and the positive electrode edge coating adhesive was obtained.

[0219] The components and proportions of Comparative Examples 1-4 are shown in Table 2.

[0220] Table 2

[0221] The positive electrode edge coating adhesive provided in this application is used in the same way as in Application Example 1.

[0222] To demonstrate the advantages of the technical solution provided in this application, the performance test data of the positive electrode edge coating adhesive provided in this application are given in Table 3.

[0223] Test method:

[0224] (1) Adhesion test (peel force test)

[0225] The positive electrode edge coating adhesive provided in Examples 1-30 and Comparative Examples 1-4 was mixed with boehmite at a mass ratio of 1:5 to form a slurry, which was then filtered to obtain a positive electrode edge coating slurry. This slurry was coated onto aluminum foil, dried to form a film, and then used to obtain a positive electrode sheet. The positive electrode sheet and a PP separator were hot-pressed together at 100°C to obtain a positive electrode sheet with a bonded separator. The separator was peeled 180 degrees upwards using a universal tensile testing machine to test the peel strength.

[0226] (2) Test of resistance to cross-contamination of positive electrode slurry

[0227] The positive electrode edge coating adhesive provided in Examples 1-30 and Comparative Examples 1-4 was mixed with boehmite at a mass ratio of 1:5 to obtain a homogeneous slurry. The slurry was then filtered to obtain the positive electrode edge coating slurry. PVDF was added to NMP and dissolved evenly. Conductive carbon was added and dispersed for 2 hours, followed by high-speed dispersion of lithium iron phosphate positive electrode material for 2 hours. The slurry was then filtered to obtain the positive electrode slurry. The solid content of the positive electrode slurry was 58%-62%, and the mass ratio of PVDF, conductive carbon, and lithium iron phosphate was 2.5:2:95.5. The positive electrode edge coating slurry and the positive electrode slurry were pipetted together, and the two slurries were brought into contact. The boundary between the two materials was observed to see if any blurring or interpenetration occurred within 3 minutes, thus determining whether there was any material cross-contamination.

[0228] (3) Electrolyte resistance test

[0229] The positive electrode edge coating adhesive provided in Examples 1-30 and Comparative Examples 1-4 was mixed with boehmite at a mass ratio of 1:5 and homogenized to obtain a positive electrode edge coating slurry. The positive electrode edge coating slurry was coated onto aluminum foil, dried to form a film, and then hot-pressed to bond with a PP separator at 100°C to obtain a positive electrode with a bonded separator. The positive electrode with the bonded separator was immersed in an electrolyte solution, and after immersion in the electrolyte solution at 60°C for 7 days, the presence of cracking or detachment of the adhesive film and separator on the electrode was observed. The electrolyte composition was: ethylene carbonate (EC): dimethyl carbonate (DMC): ethyl methyl carbonate (EMC): vinylene carbonate (VC): LiPF6 in a mass ratio of 280:94:268:28:430.

[0230] (4) Viscosity test (thixotropy)

[0231] The positive electrode edge coating adhesive provided in Examples 1-30 and Comparative Examples 1-4 was mixed with boehmite at a mass ratio of 1:5 to obtain a homogeneous slurry. The slurry was then filtered to obtain the positive electrode edge coating slurry. Viscosity was tested using a rheometer at 25°C and a shear rate of 0.1–2250 s⁻¹. -1 , through 1s -1 up to 50s -1 The viscosity change is used to reflect the thixotropy of the slurry.

[0232] Where: Thixotropic index = 1 / (1 / τ viscosity) / 50 / (1 / τ viscosity).

[0233] (5) Electrode quality

[0234] The positive electrode edge coating adhesive provided in Examples 1-30 and Comparative Examples 1-4 was mixed with boehmite at a mass ratio of 1:5 and homogenized to obtain a positive electrode edge coating slurry. The positive electrode edge coating slurry was coated onto aluminum foil, dried to form a film, and a positive electrode sheet was obtained. After folding the front and back sides, it was observed whether the electrode sheet or coating would peel off or crack.

[0235] Table 3

[0236] As shown in Table 3, the positive electrode edge coating adhesive provided in this application achieves the following performance characteristics: peel strength > 0.15 N / cm; viscosity 1 lead second > 30000.00 mPa.s, 50 lead seconds > 3000.00 mPa.s; thixotropic index > 10; after immersion in electrolyte at 60℃ for 7 days, the edge coating adhesive and the separator on the electrode sheet are firmly bonded without any peeling; the boundary between the positive electrode edge coating slurry and the positive electrode slurry is clear, with no material migration; and the electrode sheet does not exhibit brittle cracking or peeling, thus meeting the usage requirements.

[0237] Among them, a viscosity of 50 conductseconds > 3000.00 mPa·s is a basic requirement for the adhesive of the positive electrode. If this requirement cannot be met, there is no need to evaluate the thixotropic properties.

[0238] The viscosity of the positive electrode edge coating adhesive provided in Comparative Example 1 was 21621.00 mPa·s at 1 conduction second and 2361.00 mPa·s at 50 conduction seconds. This may be because the soft monomer used is octadecyl methacrylate, which has an excessively long carbon chain and insufficient free radical-induced reactivity in the system. As a result, octadecyl methacrylate cannot be completely polymerized onto the molecular chain, leading to the viscosity not meeting the standard.

[0239] The positive electrode edge coating adhesive provided in Comparative Example 2 showed creases after being soaked at 60°C for 7 days, and eventually cracked and fell off. This indicates that the acrylamide monomers and other component formulations provided in this application are beneficial for adhesion to aluminum foil and for enhancing the electrolyte immersion resistance of the positive electrode edge coating adhesive.

[0240] The viscosity of the positive electrode edge coating adhesive provided in Comparative Example 3 was 18924.00 mPa·s at 1 lead second and 2065.00 mPa·s at 50 lead seconds. This viscosity may be due to the lack of acrylic acid, resulting in incomplete reaction and thus failing to meet the standard. Since acrylic acid provides a weakly acidic environment for the system and has a strong electron-withdrawing ability, the electron cloud density decreases, which is more conducive to the attack of free radicals and further accelerates the reaction process, thereby increasing the viscosity of the electrode edge coating adhesive.

[0241] The viscosity of the positive electrode edge coating adhesive provided in Comparative Example 4 is 8681 mPa·s at 1 conductance second and 2862 mPa·s at 50 conductance seconds, with a thixotropic index of 3.03. Slight material cross-linking occurs at the overlap. It can be seen that when the cross-linking agent content is relatively low, the cross-linking density within the molecule is low, resulting in insufficient viscosity and low thixotropy of the final product.

[0242] To make the experimental results of this application more intuitive, the applicant provided a photograph of the finished product after hot pressing the positive electrode sheet and battery separator provided in Application Example 1 (Figure 1); a photograph of the electrolyte resistance test of the positive electrode sheet with bonded PP separator provided in Application Example 1 (Figure 2); and a photograph of the performance test of the positive electrode edge coating adhesive crosslinking provided in Example 1 (Figure 3). The positive electrode sheet with bonded PP separator shown in Figure 1 was cut to obtain the positive electrode sheet with bonded PP separator shown in the upper left part of Figure 2. The positive electrode sheet with bonded PP separator shown in the upper left part of Figure 2 was immersed in electrolyte, as shown in the lower left part of Figure 2. After immersion at 60°C for 7 days, the photograph shown in the lower right part of Figure 2 was obtained. The positive electrode sheet with bonded PP separator after immersion at 60°C for 7 days was taken out, and the photograph shown in the upper right part of Figure 2 was obtained. As shown in Figure 1, the positive electrode edge coating adhesive provided in this application has high peel strength. As shown in Figure 2, the positive electrode sheet of the bonded battery separator provided in Application Example 1 did not show any peeling after being soaked at 60°C for 7 days, and there was no change when folded in half. As shown in Figure 3, the two different colored positive electrode edge coating slurries (white) and positive electrode slurry (black) came into contact with each other without any material leakage or penetration.

[0243] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A positive electrode edge coating adhesive, characterized in that: It is prepared by copolymerization of the following raw materials in the following mass percentages: The sum of all components is 100%; The hard monomers include styrene; The soft monomer is one or a mixture of butyl acrylate, isooctyl acrylate, lauryl acrylate, butyl methacrylate, isooctyl methacrylate, isobornyl acrylate, and lauryl methacrylate. The first functional monomer is at least one of acrylic acid or methacrylic acid; the second functional monomer is at least one of N-methacrylamide or N-vinylpyrrolidone.

2. The positive electrode edge coating adhesive according to claim 1, characterized in that, The mass ratio of the hard monomer to the soft monomer is 4:3 to 4:

10.

3. The positive electrode edge coating adhesive according to claim 1, characterized in that, The hard monomer also includes auxiliary monomers, which are one or more of acrylonitrile, methyl acrylate, and methyl methacrylate, and the mass of styrene is not less than the sum of the masses of the auxiliary hard monomers.

4. The positive electrode edge coating adhesive according to claim 1, characterized in that, The second functional monomer also includes one or any combination of hydroxypropyl acrylate, hydroxybutyl acrylate, and hydroxyethyl acrylate.

5. The positive electrode edge coating adhesive according to claim 1, characterized in that, The crosslinking monomer is one of divinylbenzene, glycidyl methacrylate, or any mixture thereof.

6. The positive electrode edge coating adhesive according to claim 1, characterized in that, The tackifying resin is one of terpene resin, rosin resin, or any mixture thereof.

7. The positive electrode edge coating adhesive according to claim 1, characterized in that, The initiator is one or any combination of benzoyl peroxide, azobisisobutyronitrile, and azobisisoheptanenitrile.

8. The positive electrode edge coating adhesive according to claim 1, characterized in that, The solvent is N-methylpyrrolidone.

9. The method for preparing the positive electrode edge coating adhesive according to claim 1, characterized in that, The steps are as follows: 1) Weigh each component according to the mass percentage as described in claim 1; 2) After stirring the hard monomer, the first functional monomer, 35wt%-45wt% crosslinking monomer and 30wt%-40wt% solvent weighed in step 1) evenly, heat to 65-85℃, and then add some initiator to react for 1-2 hours to obtain solution (1). 3) Add the soft monomer, the second functional monomer, the remaining crosslinking monomer, the tackifying resin and the remaining initiator to the remaining solvent to obtain a mixed solution. Add the mixed solution to solution (1) dropwise and react at 75-95°C for 1-4 hours. 4) After the reaction is complete, the material is cooled and discharged to obtain the positive electrode edge coating adhesive.

10. A positive electrode plate, characterized in that, The positive electrode edge coating adhesive as described in any one of claims 1-8 is applied. The application method is to combine the positive electrode edge coating adhesive as described in any one of claims 1-8 with boehmite to form a mixed slurry with a refractory-to-solid ratio of 0.1 to 0.8, filter it, coat it on aluminum foil, and dry it to obtain a positive electrode sheet.

11. A method for bonding a positive electrode sheet to a PP separator, characterized in that, The lithium battery PP separator is covered on the positive electrode sheet as described in claim 10, and then the adhesive is fixed by hot pressing at 90-110°C.

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