Positive plate for battery as well as preparation method and application of positive plate

Abstract

The invention belongs to the technical field of battery material preparation, and relates to a battery positive plate and a preparation method and application thereof. Aiming at the technical problems in the prior art that a diaphragm is easily scratched and the risk of short circuit of a positive electrode and a negative electrode is increased due to powder falling, burrs and uneven coating on the edge of a positive electrode plate, the invention provides the positive electrode plate for the battery, which comprises a electrode plate substrate and an insulating layer arranged on the edge area of the electrode plate, the insulating layer covers the single-side or double-side edge of the pole piece; the insulating layer covers the current collector region which is not coated with the active substance along the edge of the positive plate, and can also cover the edge of the material region coated with the active substance; and the insulating layer is formed by ultraviolet curing of an ultraviolet curing coating. The invention also provides a preparation method of the positive plate for the battery, so as to solve the technical problems of infirm adhesion, insufficient temperature resistance, low production efficiency, high equipment cost and the like existing in a common edge protection mode such as an adhesive tape pasting or hot melting edge covering film process. Meanwhile, the invention also provides application of the positive plate for the battery.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of battery material preparation, and particularly relates to a positive electrode sheet for a battery, a preparation method and application thereof. BACKGROUND

[0002] A lithium ion battery, a sodium ion battery or the like secondary battery is usually composed of a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte, etc., wherein the performance of the positive electrode sheet directly affects the energy density, safety and cycle life of the battery. The common positive electrode sheet preparation process includes the steps of slurry preparation, coating, drying, compaction, slitting and winding, etc.

[0003] In actual production, the positive active material slurry will form a continuous coating after coating and drying, but in the slitting or winding process, the edge area of the electrode sheet is prone to powder falling, burr or micro-crack. These defects may cause the battery to have safety hazards such as separator scratching, positive and negative short circuit during winding or laminated assembly. In order to solve this problem, the existing technology usually uses adhesive tape, hot melt edge sealing film and the like to insulate and protect the edge of the electrode sheet.

[0004] For example, the adhesive tape is prone to edge lifting or failure in a high temperature environment, and manual attachment is low in efficiency; the hot melt edge sealing film process has a high temperature, which may cause the electrode sheet to warp or have local stress concentration, and the equipment investment is large and the energy consumption is high. Therefore, there is still a need for an improved method which is simple in process, accurate in positioning and reliable in dense insulation layer, to efficiently protect the edge of the positive electrode sheet.

[0005] In recent years, ultraviolet light curing paint has gradually been concerned and applied to the surface treatment of electrode sheets due to its fast curing speed, environmental friendliness and good chemical stability. However, there is still a lack of effective solutions on how to efficiently and accurately apply ultraviolet light curing paint to the edge area of the positive electrode sheet, and form a stable insulation layer without affecting the main performance of the electrode sheet. SUMMARY

[0006] 1. Technical problems to be solved by the present application

[0007] In view of the technical problems of powder falling, burr and uneven coating of the edge of the positive electrode sheet in the prior art, which may cause the separator to be easily scratched and increase the risk of positive and negative short circuit, the present application provides a positive electrode sheet for a battery.

[0008] The application also provides a preparation method of the positive electrode sheet for the battery, so as to solve the technical problems of the commonly used edge protection methods such as tape sticking or hot melt edge sealing film process, such as poor adhesion, insufficient temperature resistance, low production efficiency, and high equipment cost.

[0009] Meanwhile, the application also provides the application of the positive electrode sheet for the battery.

[0010] 2. Technical solutions

[0011] To achieve the above-mentioned purposes, the technical solutions provided are as follows:

[0012] Based on the purpose of the application, the first aspect of the application provides a positive electrode sheet for a battery, which comprises a sheet base and an insulating layer arranged at the edge region of the sheet; the insulating layer covers one side or both sides of the edge of the sheet; the insulating layer is formed by ultraviolet curing of ultraviolet curing paint;

[0013] The insulating layer covers the current collector region without active material coating along the edge of the positive electrode sheet;

[0014] Or the insulating layer covers the current collector region without active material coating along the edge of the positive electrode sheet, and further covers the edge of the active material coating region.

[0015] According to the positive electrode sheet for the battery of any one of the embodiments of the first aspect of the application, the insulating layer covers the current collector region without active material coating along the edge of the positive electrode sheet with a width of 0.5mm-10mm, and further covers the edge of the active material coating region with a width of 0.1mm-5mm.

[0016] By limiting the insulating layer to cover the current collector region with a width of 0.5mm-10mm and the edge of the active material coating region with a width of 0.1mm-5mm, not only can the insulating effect of the edge of the sheet be effectively ensured to prevent short circuit of the battery cell during winding or stacking, but also material waste and energy density reduction caused by excessive coverage can be avoided, so that the safety of the battery and the energy utilization rate are taken into account.

[0017] According to the positive electrode sheet for the battery of any one of the embodiments of the first aspect of the application, the thickness of the single-sided insulating coating is 10μm-50μm.

[0018] By limiting the thickness of the insulating coating to be within the range of 10μm-50μm, on the one hand, the mechanical strength of the insulating layer during slitting and curling can be ensured to avoid breaking or falling off; on the other hand, the moderate thickness will not significantly increase the thickness of the sheet and the internal resistance of the battery, so that the electrochemical performance and safety performance are taken into account.

[0019] The positive electrode sheet for a battery according to any one of the embodiments of the first aspect of the present application, the ultraviolet light-cured coating comprises 45wt%-55wt% of an acrylate resin, 12wt%-20wt% of a fluorinated modified monomer, 7wt%-13wt% of an inorganic nano-filler, 3wt%-4wt% of a photoinitiator, 1wt%-2wt% of a coupling agent, and 1wt%-2wt% of an auxiliary agent.

[0020] By optimizing the component ratio of the ultraviolet light-cured coating, the coating has appropriate adhesion, flexibility and compactness. The acrylate resin ensures film formation and strength, the fluorinated modified monomer improves the electrolyte resistance and hydrophobicity of the coating, the inorganic nano-filler enhances the insulation and thermal stability, the photoinitiator ensures fast curing efficiency, the coupling agent improves the interfacial bonding force, and the auxiliary agent improves the anti-aging performance, thereby improving the reliability and long-term stability of the insulation layer as a whole.

[0021] The positive electrode sheet for a battery according to any one of the embodiments of the first aspect of the present application, the acrylate resin is selected from one or more of polyurethane acrylate and epoxy acrylate; the fluorinated modified monomer is selected from one or more of hexafluorobutyl methacrylate and fluorinated polyether polyol; the inorganic nano-filler is selected from one or more of nano-silicon dioxide, nano-aluminum oxide, nano-boron nitride and boehmite; the photoinitiator is selected from one or more of diphenyl phosphine oxide, isopropyl thioxanthone and hydroxyl cyclohexyl phenyl ketone; the coupling agent is a silane coupling agent; and the auxiliary agent is an antioxidant.

[0022] By selecting specific types of raw materials, not only the adhesion of the coating to the current collector and the active material layer is improved, but also the electrolyte corrosion resistance, thermal stability and insulation performance of the coating are further enhanced. For example, the fluorinated monomer can impart better hydrophobicity and corrosion resistance, the nano-filler can significantly improve the insulation strength and flame retardant performance, and the photoinitiator can achieve fast curing, thereby obtaining an insulation layer that still has stability under high rate and large capacity battery working conditions.

[0023] Preferably, the coupling agent is gamma-methacryloxypropyl trimethoxysilane, and the auxiliary agent is benzotriazole.

[0024] Based on the purpose of the present application, the second aspect of the present application provides a preparation method of a positive electrode sheet for a battery, which comprises the steps of slurry preparation, coating, drying, compaction, slitting and winding in sequence. Before or after the winding step is completed, the ultraviolet light-cured coating is applied to the edge area of the positive electrode sheet by an ultraviolet light jet printing device provided with a visual positioning system, to form a compact insulation layer.

[0025] The UV printing of the insulating layer before the turret assembly of the battery cell can ensure the assembly precision of the pole piece, avoid damage to the insulating layer in subsequent processes, significantly improve the process stability and product consistency, and simplify the process and reduce the repair rate.

[0026] According to the preparation method of the positive pole piece for the battery according to any embodiment of the second aspect of the application, after the winding and slicing are completed, the positive pole piece enters a battery cell assembly line, and the battery cell assembly line includes a turret assembly step. Before the turret assembly, the ultraviolet light curing paint is coated on the edge area of the positive pole piece by the ultraviolet light printing equipment provided with a visual positioning system to form a dense insulating layer.

[0027] According to the preparation method of the positive pole piece for the battery according to any embodiment of the second aspect of the application, the viscosity of the ultraviolet light curing paint is < 50 mPa·s.

[0028] By limiting the viscosity of the paint to be < 50 mPa·s, the paint can have good fluidity and jet forming property during printing, so as to ensure clear coating boundary and uniform thickness, avoid process defects such as accumulation, wire drawing or splashing, and improve the consistency and density of the insulating layer.

[0029] According to the preparation method of the positive pole piece for the battery according to any embodiment of the second aspect of the application, the working parameters of the ultraviolet light printing equipment are as follows: wavelength 320 nm-400 nm, irradiation energy 300 mJ / cm 2 -1000 mJ / cm 2 , and curing time 0.5 m / s-5 m / s.

[0030] By optimizing the wavelength, irradiation energy and curing time of the printing equipment, efficient curing of the paint can be completed in a very short time, the coating structure is dense and firmly combined with the substrate, and thermal damage to the pole piece caused by excessive irradiation is avoided. This process scheme realizes the preparation of an insulating layer with high efficiency, low energy consumption and high stability.

[0031] Preferably, the printing process has a positioning accuracy of ≤±50 μm and a printing speed of 5 m / min-100 m / min.

[0032] Based on the purpose of the application, the third aspect of the application provides an application of a positive pole piece for a battery, characterized in that the positive pole piece for a battery according to claim 1 is applied in the preparation of a power battery for an electric vehicle, a portable energy storage device or a high-rate electronic device power supply system.

[0033] Any embodiment of any aspect of the present application can be combined with any other embodiment of the same aspect or other aspects of the present application. Furthermore, any feature of any aspect of the present application can be applied to other aspects of the present application, in any embodiment of the present application, where appropriate.

[0034] Any feature of any aspect of the present application or any embodiment of the same aspect or other aspects of the present application can be applied to any other embodiment of the same aspect or other aspects of the present application, where appropriate, with appropriate modifications, where necessary, and in any combination, unless the context requires otherwise. Various aspects and features of the present application are described in further detail below.

[0035] 3. Beneficial Effects

[0036] Compared with the prior art, the technical solutions provided by the present application have the following beneficial effects:

[0037] (1) The positive electrode sheet for batteries has excellent mechanical flexibility and adhesion. The insulating layer has no cracks or peeling when bent 90° on a 32 mm diameter shaft rod, and the adhesion level is 0-1 grade, which can maintain the integrity in subsequent processes such as slitting, curling and winding. It has high electrical insulation performance and dielectric resistance, with an insulating layer breakdown voltage of ≥1000 V, which can effectively prevent short circuit and penetration failure at the edge of the sheet. It has excellent electrolyte resistance: the volume swelling rate is <5% after soaking in 60℃ electrolyte for 7 days, which ensures the dimensional stability and insulation reliability in long-term soaking environment. It has a structural protection function: the insulating layer covers the uncoated current collector area and extends to the edge of the material area, which can effectively isolate the edge of the active material from external components, reduce the risk of edge short circuit and partial discharge, and improve the safety and consistency of the battery cell.

[0038] (2) The preparation method of the positive electrode sheet for batteries simplifies the coating process and reduces equipment investment. It does not need to prepare and mix ceramic slurry, avoids the strict control of die gap, gasket opening and slurry supply pressure in traditional external / internal ceramic coating, cancels the mixing equipment, thereby significantly reducing the equipment cost and production line complexity. It improves the process stability and consistency, realizes high-precision positioning through visual positioning, and easily controls the printing parameters, reduces the size or thickness deviation of the coating layer caused by die or supply fluctuation, and improves the consistency and yield of the finished product. It improves the production efficiency and controllability, realizes high-speed online production through instant curing of printing and ultraviolet light, shortens the curing time, and is easy to integrate into the existing battery assembly line, reduces the amount of manual debugging, and obtains excellent insulating layer quality. Through controllable formula and printing parameters, the prepared insulating layer is dense and firmly adhered, which can not be easily broken or peeled off during subsequent slitting and curling processes, ensuring long-term reliable operation of the battery cell.

[0039] (3) The positive electrode sheet for battery of the present application is applied to electric vehicle power battery, portable energy storage device or high rate electronic device power supply system: significantly improves the safety of the battery cell, the dense edge insulation layer effectively prevents the edge short circuit and local penetration failure of the electrode sheet, reduces the risk of thermal runaway and safety accidents; improves the reliability and life of the battery, the excellent adhesion, electrolyte resistance and mechanical flexibility reduce the insulation failure caused by slitting / winding process, thereby improving the consistency and cycle stability of the battery; adapts to high energy density and high rate requirements, the insulation sheet maintains high electrical insulation without affecting the electrode assembly and electrochemical performance, and is suitable for power and energy storage scenarios with high requirements for safety and performance; conducive to industrialization and popularization, the matched online printing and ultraviolet curing preparation method is easy to integrate with the existing process and is convenient for stable application on large-scale production line. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 Positioning diagram of UV printing equipment set in the positive electrode sheet coating process in the embodiment of the present application;

[0041] Figure 2 Positioning diagram of UV printing equipment set in the positive electrode sheet roll division process in the embodiment of the present application;

[0042] Figure 3 Structure diagram of the positive electrode sheet after the edge of the positive electrode sheet is formed with an insulation layer by UV printing in the embodiment of the present application;

[0043] Figure 4 Coating thickness distribution comparison diagram of the embodiment and the comparative example of the present application;

[0044] Figure 5 Coating width distribution comparison diagram of the embodiment and the comparative example of the present application. DETAILED DESCRIPTION

[0045] The present application will be further described below in combination with specific embodiments.

[0046] The technical solutions in the embodiments of the present application will be described below clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present application, not all the embodiments; based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0047] The thickness of the insulating coating in the present application is measured by the following method: firstly, the thickness of the positive electrode sheet after being coated with the insulating layer is measured by using a vernier caliper; secondly, the thickness of the positive electrode sheet substrate without being coated with the insulating layer is measured; finally, the difference between the overall thickness and the substrate thickness is taken as the thickness of the insulating layer. This method can more accurately reflect the actual covering thickness of the coating on the electrode sheet, and has the advantages of simple operation and good repeatability.

[0048] Example 1

[0049] The method for preparing the positive electrode sheet for the battery of the present embodiment includes the steps of slurry preparation, coating, drying, compaction, slitting, and winding the slices. The specific preparation process is shown in the following figure: Figure 1 After the positive electrode aluminum foil is coated on one side in the machine head, it flows to the tail through the lower oven to continue coating the other side, and forms an electrode roll after drying in the oven. After the oven, the ultraviolet light jet printing equipment is added at the edge of the positive and negative material area respectively. Two ultraviolet light jet printing equipments are arranged on each side of the material area, and the jet printing speed matches the coating speed. In the present embodiment, the jet printing speed is 50 m / min. After jet printing, the edge of the electrode sheet is immediately subjected to ultraviolet light curing, the wavelength of the ultraviolet light is 365 nm, the irradiation energy is 500 mJ / cm 2 , the length of the curing area along the running direction is 0.3 m, and the curing time is 0.36 s (i.e. 0.83 m / s). In other embodiments, the wavelength of the ultraviolet light is 320 nm to 400 nm, the irradiation energy is 300 mJ / cm 2 ~1000 mJ / cm 2 , and the curing time is 0.5 m / s to 5 m / s, which can also achieve the same technical effects.

[0050] The ultraviolet light curing paint used in the present embodiment includes: acrylate resin, fluorinated modified monomer, inorganic nano filler, photoinitiator, coupling agent and auxiliary agent. In the present embodiment, the mass percentage of each component is: polyurethane acrylate resin 55%, hexafluorobutyl methacrylate 20%, modified nano-SiO2 12%, TPO [diphenyl phosphine oxide, diphenyl (2,4,6-trimethyl benzoyl) phosphine oxide] photoinitiator 3%, KH-570 (gamma-methacryloxypropyl trimethoxysilane) silane coupling agent 1%, benzotriazole 2%. The viscosity of the ultraviolet light curing paint is 18 mPa·s.

[0051] The positive electrode sheet for a battery of the present embodiment includes a sheet substrate and an insulating layer provided at the edge region of the sheet; the insulating layer covers both sides of the sheet edge; the insulating layer covers the current collector region where no active material is coated along the edge of the positive electrode sheet, and further covers the edge of the material region where active material is coated. In the present embodiment, the obtained insulating layer width is 2.28 mm, the size of the current collector region where no active material is coated is 1.93 mm, the size of the material region covered is 0.35 mm, and the double-sided thickness is 50.26 μm.

[0052] The positive electrode sheet is wound into a core with a conventional negative electrode sheet, and the core is subjected to steps such as assembly, liquid injection, and formation to obtain a battery cell.

[0053] Example 2

[0054] The positive electrode sheet for a battery of the present embodiment and the method for producing the same are basically the same as in Example 1, except that Al2O3 ceramic slurry is added to the ultraviolet light-curable coating material to reduce the cost, and the composition mass percentage is as follows: polyurethane acrylate resin 40%, hexafluorobutyl methacrylate 15%, TPO photoinitiator 4%, Al2O3 ceramic slurry (solid content 30%) 25%, KH-570 silane coupling agent 1.5%, and benzotriazole 1.5%. The jet printing speed is 10 m / min, and the curing energy is 800 mJ / cm 2 . The viscosity of the ultraviolet light-curable coating material is 43 mPa·s.

[0055] In the present embodiment, the obtained insulating layer width is 2.30 mm, the size of the current collector region where no active material is coated is 1.98 mm, the size of the material region covered is 0.32 mm, and the double-sided thickness is 50.15 μm.

[0056] Example 3

[0057] The positive electrode sheet for a battery of the present embodiment and the method for producing the same are basically the same as in Example 2, except that the ceramic slurry in the ultraviolet light-curable coating material is replaced with boehmite (AlOOH) slurry, and the composition mass percentage is as follows: epoxy acrylate resin 50%, fluorinated polyether polyol 12%, nano-BN 8%, photoinitiator 3%, and boehmite slurry (solid content 25%) 27%. The jet printing speed is 10 m / min, and the curing energy is 800 mJ / cm 2 . The viscosity of the ultraviolet light-curable coating material is 38 mPa·s.

[0058] In the present embodiment, the obtained insulating layer width is 2.29 mm, the size of the current collector region where no active material is coated is 1.98 mm, the size of the material region covered is 0.31 mm, and the double-sided thickness is 50.29 μm.

[0059] Comparative Example 1

[0060] The preparation method of the positive plate for a battery of the present comparative example is basically the same as that of Example 1, except that the edge of the positive plate is not provided with an insulating coating.

[0061] Comparative Example 2

[0062] The preparation method of the positive plate for a battery of the present comparative example is basically the same as that of Example 1, except that the edge insulating layer of the positive plate adopts a ceramic insulating layer in the prior art.

[0063] In the present comparative example, the width of the obtained insulating layer is 2.36 mm, the size of the current collector region covered by the insulating layer without active material is 1.96 mm, the size of the covered material region is 0.40 mm, and the double-sided thickness is 50.04 μm.

[0064] Performance comparison test

[0065] The positive plates prepared in Examples 1-3 and Comparative Examples 1-2 above are each taken as 5 groups of samples for performance test, and the test results of different indexes are obtained and summarized in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] As can be seen from Table 1, after the ultraviolet light curing paint is used to replace the traditional ceramic slurry, the peeling strength of the edge coating of the positive plate is significantly improved. In combination with the fact that the thickness and width distribution of the coating of the positive plate prepared in Examples 1-3 are better than those of the traditional ceramic insulating layer in Comparative Example 2, and the overall uniformity is obviously improved. Figure 4 and Figure 5 It can be seen that the thickness and width distribution of the coating of the positive plate prepared in Examples 1-3 are better than those of the traditional ceramic insulating layer in Comparative Example 2, and the overall uniformity is obviously improved.

[0070] In summary, the performance test results show that the edge coating of the positive plate prepared by the ultraviolet jet printing method of the present application is significantly better than the traditional ceramic insulating layer in terms of peeling strength and breakdown voltage, thereby effectively improving the comprehensive performance of the positive plate.

[0071] Example 4

[0072] The preparation method of the positive plate for a battery of the present example is basically the same as that of Example 1, except that the insulating layer only covers one side edge of the plate.

[0073] In the present example, the width of the obtained insulating layer is 2.04 mm, the size of the current collector region covered by the insulating layer without active material is 2.04 mm, the size of the covered material region is 0 mm, and the single-sided thickness is 50.50 μm.

[0074] Example 5

[0075] The preparation method of the positive electrode sheet for the battery of the present example is basically the same as that of Example 1, except that the preparation process is as follows: Figure 2 After the coating is completed, the positive electrode sheet enters the next rolling and slitting process, which includes a turret unwinding step. After the turret unwinding step, the ultraviolet light curing paint is applied to the edge area of the positive electrode sheet by the ultraviolet light jet printing equipment provided with a visual positioning system, forming a dense insulating layer.

[0076] In the present example, the width of the obtained insulating layer is 2.30 mm, the size of the current collector area without coated active material is 2.00 mm, the size of the covered area is 0.30 mm, and the double-sided thickness is 50.08 μm.

[0077] Comparative Example 3

[0078] The preparation method of the positive electrode sheet for the battery of the present example is basically the same as that of Example 1, except that the insulating layer only covers the area.

[0079] In the present example, the width of the obtained insulating layer is 0.43 mm, the size of the current collector area without coated active material is 0 mm, the size of the covered area is 0.43 mm, and the thickness is 49.89 μm.

[0080] Comparative Example 4

[0081] The preparation method of the positive electrode sheet for the battery of the present example is basically the same as that of Example 1, except that the insulating layer only covers the aluminum foil area.

[0082] In the present example, the width of the obtained insulating layer is 2.05 mm, the size of the current collector area without coated active material is 2.05 mm, the size of the covered area is 0 mm, and the double-sided thickness is 50.20 μm.

[0083] Comparative Example 5

[0084] The preparation method of the positive electrode sheet for the battery of the present example is basically the same as that of Example 1, except that the coating thickness is 18.10 μm.

[0085] In the present example, the width of the obtained insulating layer is 2.34 mm, the size of the current collector area without coated active material is 1.95 mm, the size of the covered area is 0.39 mm, and the thickness is 30.10 μm.

[0086] Comparative Example 6

[0087] The preparation method of the positive electrode sheet for the battery of the present example is basically the same as that of Example 1, except that the viscosity of the ultraviolet light curing paint is > 50 mPa·s, which is 84 mPa·s.

[0088] In this comparative example, the width of the obtained insulation layer is 2.14 mm, the size of the current collector area covered by the uncoated active material is 1.90 mm, the size of the covering material area is 0.24 mm, and the thickness is 59.18 μm.

[0089] Comparative Example 7

[0090] The preparation method of the positive electrode sheet for the battery in this comparative example is basically the same as that in Example 1, except that the coating width is 1.82 mm.

[0091] In this comparative example, the width of the insulating layer is 1.82 mm, the size of the current collector area covered by the uncoated active material is 0.30 mm, the size of the material covering area is 1.52 mm, and the double-sided thickness is 50.25 μm.

[0092] Table 2

[0093]

[0094]

[0095] As shown in Table 2:

[0096] (1) In Comparative Example 3, the insulation layer only covers the material area and does not cover the current collector area (coverage size is 0 mm). This design results in exposed electrode edges, which cannot effectively prevent short circuits at the electrode edges and poses a risk of localized penetration failure. At the same time, compared with Example 1, its peel strength is significantly lower and its bending performance does not meet the requirements for use.

[0097] (2) In Comparative Example 4, the insulation layer only covered the current collector area and did not extend to the coating area (the size of the coating area was 0 mm). Although the overall performance was similar to that of Example 1, due to the exposed edge of the coating area, there was still a potential risk of burrs piercing the diaphragm and causing cell failure, and the comprehensive protection effect expected by the present invention was not achieved.

[0098] (3) In Comparative Example 5, the insulation coating thickness is relatively low, the corresponding breakdown voltage is low, and the insulation protection effect is significantly worse than that of Example 1, making it difficult to provide stable protection under high voltage or winding conditions.

[0099] (4) In Comparative Example 6, the viscosity of the coating used was significantly higher than that in Example 1. Although the coating thickness and breakdown voltage were improved, the high viscosity easily caused ink clogging of the print head, which in turn caused poor printing thickness and size consistency, increasing production difficulty and defect rate.

[0100] (5) In Comparative Example 7, the insulation layer coating width is smaller than that in Example 1. Similar to Comparative Example 3, it cannot effectively cover the edge area of ​​the electrode sheet, and there is a risk of short circuit and local penetration failure.

[0101] In summary, the insulating layer in Example 1 simultaneously covers both the current collector area and the edge of the material area, and the coating thickness, viscosity, and printing width are all controlled within a reasonable range. This ensures high adhesion and insulation strength while achieving excellent printing consistency and process stability, significantly outperforming the comparative schemes. This verifies that the design concept of the dual-zone coverage structure and low-viscosity UV-curable coating in this invention has significant advantages in terms of electrical insulation, mechanical reliability, and process adaptability.

[0102] The positive electrode sheets for batteries described in the embodiments of this application can all be used in the preparation of power batteries for electric vehicles, portable energy storage devices, or power systems for high-rate electronic devices.

Claims

1. A positive electrode sheet for a battery, characterized in that: The positive electrode sheet for the battery includes an electrode substrate and an insulating layer disposed in the edge region of the electrode sheet; The insulating layer covers one or both edges of the electrode sheet; The insulating layer is formed by UV-curing a UV-curable coating. The insulating layer covers the current collector area without active material along the edge of the positive electrode sheet; or the insulating layer covers the current collector area without active material along the edge of the positive electrode sheet, and further covers the edge of the material area with active material.

2. The positive electrode sheet for batteries according to claim 1, characterized in that: The insulating layer covers the current collector area without active material coating along the edge of the positive electrode sheet with a width of 0.5 mm to 10 mm, and further covers the edge of the material area coated with active material with a width of 0.1 mm to 5 mm.

3. The positive electrode sheet for batteries according to claim 1, characterized in that: The thickness of the single-sided insulating coating is 10μm to 50μm.

4. The positive electrode sheet for a battery according to any one of claims 1-3, characterized in that: The UV-curable coating comprises 45wt% to 55wt% of acrylate resin, 12wt% to 20wt% of fluorinated modified monomer, 7wt% to 13wt% of inorganic nanofiller, 3wt% to 4wt% of photoinitiator, 1wt% to 2wt% of coupling agent, and 1wt% to 2wt% of additives.

5. The positive electrode sheet for a battery according to claim 4, characterized in that: The acrylate resin is selected from one or more of polyurethane acrylate and epoxy acrylate; the fluorinated modified monomer is selected from one or more of hexafluorobutyl methacrylate and fluorinated polyether polyol; the inorganic nanofiller is selected from one or more of nano silica, nano alumina, nano boron nitride, and boehmite; the photoinitiator is selected from one or more of diphenylphosphine oxide, isopropylthioxanthone, and hydroxycyclohexylphenyl ketone; the coupling agent is a silane coupling agent; and the additive is an antioxidant.

6. A method for preparing a positive electrode sheet for a battery according to any one of claims 1-5, comprising the steps of slurry preparation, coating, drying, compaction, slitting, and winding the sheets, characterized in that: Before or after the winding and slicing step is completed, the ultraviolet curing coating is applied to the edge area of ​​the positive electrode sheet using an ultraviolet inkjet printing device equipped with a visual positioning system to form a dense insulating layer.

7. The method for preparing the positive electrode sheet for a battery according to claim 6, characterized in that: After the positive electrode sheet is wound and sliced, it enters the cell assembly line. The cell assembly line includes a turret assembly step. Before the turret assembly, the ultraviolet curing coating is applied to the edge area of ​​the positive electrode sheet by an ultraviolet inkjet printing device equipped with a vision positioning system to form a dense insulating layer.

8. The method for preparing a positive electrode sheet for a battery according to any one of claims 7 or 8, characterized in that: The viscosity of the UV-curable coating is <50 mPa·s.

9. The method for preparing a positive electrode sheet for a battery according to claim 8, characterized in that: The operating parameters of the ultraviolet inkjet printing equipment are: wavelength 320nm~400nm, irradiation energy 300mJ / cm². 2 ~1000mJ / cm 2 The curing time is 0.5m / s to 5m / s.

10. The application of positive electrode plates for batteries, characterized in that: The positive electrode sheet for batteries according to claim 1 is applied to the preparation of power batteries for electric vehicles, portable energy storage devices, or power systems for high-rate electronic devices.

Images