A positive electrode slurry, a preparation method thereof, a positive electrode sheet, and a lithium battery

Abstract

The application discloses a positive electrode paste, a preparation method thereof, a positive electrode sheet and a lithium battery, and belongs to the technical field of lithium ion batteries.The positive electrode paste provided by the application comprises, in parts by mass, 100 parts of a positive electrode active material, 1-10 parts of a conductive agent, 0.5-5 parts of a binder, 1-20 parts of a phosphate modified polyurethane acrylate oligomer, 0.1-5 parts of a radiation-sensitive initiator, 0.1-5 parts of a photoinitiator, 0.1-10 parts of a co-initiator, 0.01-5 parts of an X-ray long-afterglow luminescent material and a dispersion solvent.The positive electrode paste provided by the application can realize rapid cross-linking polymerization under X-ray irradiation after being coated on a current collector, a three-dimensional network structure formed by the positive electrode paste effectively enhances the cohesion and flexibility of an electrode coating, and the problem of insufficient flexibility and surface cracking of a thick electrode caused by stress concentration during a drying and rolling process is significantly improved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a positive electrode slurry and its preparation method, a positive electrode sheet, and a lithium battery. Background Technology

[0002] In the preparation of positive electrode sheets for lithium-ion batteries, positive electrode active materials, conductive agents, and binders are typically mixed to form a slurry, which is then coated onto the surface of an aluminum foil current collector and processed through drying, rolling, and other steps. As the requirements for battery energy density continue to increase, the positive electrode coating layer tends to be thicker. However, thick electrodes are prone to reduced flexibility and coating cracking due to internal stress concentration during drying and subsequent processing, which in turn affects battery performance and yield.

[0003] To improve the mechanical properties of electrodes, existing technologies often employ the addition of polymer toughening agents, combined with photocuring technology to achieve cross-linking enhancement. However, traditional UV curing methods are limited by their weak penetration ability. For thick electrode coatings containing a large number of opaque inorganic particles, it is difficult to achieve deep and uniform curing, which easily leads to problems such as incomplete internal cross-linking, insufficient curing depth, and excessively long curing time. This restricts the improvement of production efficiency and the application of thick electrodes in high-energy-density batteries. Summary of the Invention

[0004] In view of this, the present invention provides a positive electrode slurry and its preparation method, a positive electrode sheet, and a lithium battery. The present invention significantly improves the flexibility and crack resistance of thick electrode sheets by introducing X-ray long-afterglow luminescent materials into the positive electrode slurry and combining them with a composite initiation system to achieve deep and rapid curing using X-ray irradiation.

[0005] In a first aspect, the present invention provides a positive electrode slurry, comprising, by weight: 100 parts of positive electrode active material; 1-10 parts of conductive agent; 0.5 to 5 parts of adhesive; 1-20 parts of phosphate-modified polyurethane acrylate oligomer; 0.1 to 5 parts of radiation-sensitive initiator; Photoinitiator 0.1-5 parts; Total initiator: 0.1-10 parts; 0.01~5 parts of X-ray long afterglow luminescent material; Dispersing solvent.

[0006] Preferably, the number average molecular weight of the phosphate-modified polyurethane acrylate oligomer is 1500~8000 g / mol.

[0007] Preferably, the radiation-sensitive initiator is selected from at least one of halogenated compounds, iodonium salts, matte salts, or metallocene compounds.

[0008] Furthermore, the halogenated compound is carbon tetrabromide, the iodonium salt is diphenyliodonium hexafluorophosphate, and the metallocene compound is ferrocene.

[0009] Preferably, the photoinitiator is selected from at least one of anthraquinone compounds or thioxanthone compounds.

[0010] Preferably, the co-initiator is selected from at least one of amine compounds, alcohol compounds, or thiols.

[0011] Furthermore, the amine compound is triethanolamine or methyldiethanolamine; the alcohol compound is isopropanol; and the thiol compound is pentaerythritol tetra-3-mercaptopropionate.

[0012] Preferably, the X-ray long afterglow luminescent material is a rare-earth ion-doped fluoride with the general chemical formula AreF4:Ln 3+ Where A is an alkali metal ion selected from Li + Na + K + One or more of the following; Re is a matrix rare earth ion selected from Y 3+ Lu 3+ Gd 3+ One or more of the following; Ln is the luminescent center rare earth ion selected from Tb 3+ Eu 3+ Ce 3+ One or more of them.

[0013] Secondly, the present invention provides a method for preparing the above-mentioned positive electrode slurry, comprising the following steps: Under light-shielding conditions, phosphate-modified polyurethane acrylate oligomer, radiation-sensitive initiator, photoinitiator, co-initiator, and X-ray long afterglow luminescent material are added to a portion of the dispersion solvent and stirred until homogeneous to obtain a premixed solution. The positive electrode active material, conductive agent, and binder are mixed with the remaining dispersing solvent and stirred to disperse, thus obtaining the main material slurry. The premixed liquid and the main material slurry are mixed and then degassed to obtain the final product.

[0014] Thirdly, the present invention provides a positive electrode sheet, which is prepared from the above-mentioned positive electrode slurry or the positive electrode slurry prepared by the above-mentioned preparation method.

[0015] Fourthly, the present invention provides a method for preparing the above-mentioned positive electrode sheet, comprising the following steps: The positive electrode slurry is coated on the surface of the current collector, pre-dried, and then placed in an X-ray irradiation device for irradiation treatment. Finally, it is rolled to obtain the positive electrode sheet.

[0016] Preferably, the irradiation treatment parameters are as follows: X-ray energy of 80~150 keV, radiation dose rate of 50~200 Gy / s, and irradiation time of 10~60 seconds.

[0017] Fifthly, the present invention provides a lithium battery comprising the above-described positive electrode sheet or a positive electrode sheet prepared by the above-described preparation method.

[0018] Compared with the prior art, the present invention has achieved the following beneficial effects: (1) This invention introduces phosphate-modified polyurethane acrylate oligomers into the positive electrode slurry. The composite initiation system composed of radiation-sensitive initiators, photoinitiators, co-initiators and X-ray long afterglow luminescent materials works synergistically to achieve rapid cross-linking polymerization under X-ray irradiation. The resulting three-dimensional network structure effectively enhances the cohesion and flexibility of the electrode coating, significantly improving the problem of insufficient flexibility and surface cracking caused by internal stress concentration during the drying and rolling process of thick electrodes, thereby improving the mechanical stability of the electrode and the product yield.

[0019] (2) This invention utilizes the high penetration characteristics of X-rays, which can penetrate thick electrode coatings (>200 μm) containing a large number of opaque inorganic particles. Combined with the direct response of radiation-sensitive initiators to high-energy rays and the indirect effect of X-ray long-afterglow luminescent materials absorbing energy and continuously emitting light to excite photoinitiators, uniform and thorough curing from the inside of the coating to the surface is achieved. This overcomes the technical bottleneck of traditional ultraviolet curing technology, which suffers from incomplete deep curing and long curing time due to weak penetration ability. It significantly shortens the curing process time and improves production efficiency.

[0020] (3) The positive electrode sheet prepared by the present invention has excellent flexibility and crack resistance while maintaining a high content of active materials, which is conducive to the preparation of thick electrodes to improve the energy density of the battery. The electrode sheet has high peel strength and structural integrity, which helps to build a stable electronic conductive network, thereby ensuring the cycle stability and rate performance of the battery and meeting the industrial production needs of high energy density lithium-ion batteries. Attached Figure Description

[0021] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation thereof. Obviously, those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0022] Figure 1 This is a schematic diagram of the preparation process in Embodiment 1 of the present invention. Detailed Implementation

[0023] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0024] This invention provides a positive electrode slurry, comprising, by weight: 100 parts of positive electrode active material; 1-10 parts of conductive agent; 0.5 to 5 parts of adhesive; 1-20 parts of phosphate-modified polyurethane acrylate oligomer; 0.1 to 5 parts of radiation-sensitive initiator; Photoinitiator 0.1-5 parts; Total initiator: 0.1-10 parts; 0.01~5 parts of X-ray long afterglow luminescent material; Dispersing solvent.

[0025] The positive electrode slurry of this invention contains phosphate-modified polyurethane acrylate oligomers as a functional resin component for enhancing flexibility and preventing cracking, and is combined with a composite initiation system consisting of a radiation-sensitive initiator, a photoinitiator, a co-initiator, and an X-ray long-afterglow luminescent material. Under X-ray irradiation conditions, this composite initiation system can produce a dual curing effect. On the one hand, the radiation-sensitive initiator directly responds to high-energy rays to generate active species; on the other hand, the long-afterglow luminescent material converts X-ray energy into visible light, thereby exciting the photoinitiator to generate active species. The synergistic effect of these two factors initiates the rapid cross-linking polymerization of the phosphate-modified polyurethane acrylate oligomers, forming a three-dimensional network structure within the electrode coating, significantly improving the flexibility and crack resistance of the electrode. Simultaneously, the high penetration characteristics of X-rays ensure deep and uniform curing of the thick electrode coating, overcoming the limitation of limited penetration depth in traditional ultraviolet curing.

[0026] The positive electrode active material described in this invention is the main component that participates in the electrochemical reaction and provides capacity, and can be selected from various positive electrode materials known in the art. In some embodiments, the positive electrode active material can be selected from one or more of lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium cobalt oxide, lithium manganese oxide, or lithium-rich manganese-based materials. Among them, lithium nickel cobalt manganese oxide can be selected from systems such as NCM523, NCM622, and NCM811. Preferably, the positive electrode active material is lithium iron phosphate or the high-nickel ternary material NCM811 to meet the requirements of high energy density batteries.

[0027] In this invention, the conductive agent is used to construct an electronic conductive network inside the electrode, reducing electrode resistance. In some embodiments, the conductive agent is selected from one or more of conductive carbon black, carbon nanotubes, graphene, carbon fiber, or Ketjen black. The conductive carbon black can be Super P, acetylene black, etc., and the carbon nanotubes can be multi-walled or single-walled carbon nanotubes, with a preferred diameter of 5-20 nm and a preferred length of 1-20 μm. The graphene sheet diameter is preferably 0.5-10 μm. Preferably, the conductive agent is a composite of conductive carbon black and carbon nanotubes, utilizing both the low cost and high dispersibility of conductive carbon black and the aspect ratio advantage of carbon nanotubes to construct a more complete conductive network. The mass ratio of conductive carbon black to carbon nanotubes can be 1:1 to 5:1, for example, 2:1, 3:1, or 4:1.

[0028] The amount of conductive agent should be controlled within the range of 1 to 10 parts. If the amount is less than 1 part, the conductive network will be incomplete, and the internal resistance of the electrode will increase; if the amount is more than 10 parts, the proportion of active material will be relatively reduced, affecting the energy density. The preferred amount of conductive agent is 2 to 8 parts, more preferably 3 to 6 parts, for example, it can be 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts, 6.5 parts, 7 parts, 7.5 parts, 8 parts, 8.5 parts, 9 parts or 9.5 parts.

[0029] In this invention, the binder is used to provide basic bonding strength between the active material, the conductive agent, and the current collector, ensuring the structural integrity of the electrode. In some embodiments, the binder is selected from one or more of polyvinylidene fluoride, sodium carboxymethyl cellulose, styrene-butadiene rubber, and polyacrylic acid. When using an oil-based system, the binder is preferably polyvinylidene fluoride, and the dispersing solvent is N-methylpyrrolidone accordingly. When using an aqueous system, the dispersing solvent is water accordingly. The amount of binder needs to be controlled within the range of 0.5 to 5 parts. If the amount is less than 0.5 parts, the bonding strength is insufficient, and the electrode is prone to powdering; if the amount is more than 5 parts, the content of insulating binder is too high, affecting the conductivity and energy density of the electrode. The amount of binder is preferably 1 to 4 parts, more preferably 1.5 to 3 parts, for example, it can be 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, or 5 parts.

[0030] In this invention, the dispersing solvent is used to dissolve or disperse the components and adjust the slurry to a suitable coating viscosity. The amount of dispersing solvent used is determined by ensuring that the slurry viscosity is within a suitable range for coating. In some embodiments, the viscosity of the positive electrode slurry is 3000~8000 mPa·s. If the viscosity is too low, it is prone to sagging and uneven thickness during coating; if the viscosity is too high, coating is difficult and scratches are easily generated. The amount of solvent can be adjusted according to the specific formulation and process requirements, and it usually accounts for 30%~60% of the total mass of the slurry.

[0031] In this invention, the phosphate-modified polyurethane acrylate oligomer is the core functional resin, which forms a three-dimensional network structure after curing, imparting excellent flexibility and cohesiveness to the electrode coating. The molecular structure of this oligomer includes polyurethane segments, acrylate groups, and phosphate groups. The polyurethane segments are formed by the reaction of polyols and diisocyanates, providing the polymer with flexibility and mechanical strength; the acrylate groups provide crosslinkable carbon-carbon double bonds, serving as reaction sites for the polymerization reaction; and the phosphate groups enhance affinity and adhesion to the surface of inorganic active materials, strengthening interfacial bonding. In some embodiments, the number-average molecular weight of the phosphate-modified polyurethane acrylate oligomer is 1500-8000 g / mol, more preferably 2000-6000 g / mol. The amount of this oligomer should be controlled within the range of 1-20 parts. If the amount is less than 1 part, the flexibility-enhancing effect is not significant; if the amount is more than 20 parts, the excessive resin content may affect the conductivity and energy density of the electrode. The preferred amount of the oligomer is 3 to 15 parts, more preferably 5 to 12 parts, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, 16 parts, 17 parts, 18 parts, 19 parts or 20 parts.

[0032] In some embodiments, the phosphate-modified polyurethane acrylate oligomers can be prepared using polyurethane acrylate synthesis methods known in the art. The preparation process typically includes: first, reacting a polyol with an excess of diisocyanate to generate an isocyanate-terminated polyurethane prepolymer; then, introducing a compound containing phosphate groups into the prepolymer chain segments; and finally, end-capping with a hydroxyl-containing acrylate monomer to introduce crosslinkable acrylate double bonds at the polymer chain ends. The molecular weight of the oligomer can be controlled by adjusting the type, ratio, and reaction conditions of the reactants. Those skilled in the art can prepare phosphate-modified polyurethane acrylate oligomers that meet the requirements of this invention by adjusting the type, ratio, and reaction conditions of the reactants, based on existing technical knowledge.

[0033] In this invention, the radiation-sensitive initiator directly responds to secondary electrons generated by X-ray irradiation. Upon absorbing energy, it undergoes molecular bond breakage, generating active free radicals or cations capable of initiating the polymerization of acrylate double bonds. In some embodiments, the radiation-sensitive initiator is selected from at least one of halogenated compounds, iodonium salts, sulfonium salts, or metallocene compounds. Halogenated compounds, such as carbon tetrabromide, have low C-Br bond energies and readily break under radiation to generate free radicals; iodonium salts, such as diphenyliodonium hexafluorophosphate, can decompose under radiation to generate cations and free radicals; metallocene compounds, such as ferrocene, can act as electron donors in radiochemical reactions. Preferably, the radiation-sensitive initiator is carbon tetrabromide or diphenyliodonium hexafluorophosphate.

[0034] The amount of radiation-sensitive initiator should be controlled within the range of 0.1 to 5 parts. If the amount is less than 0.1 parts, the initiation efficiency will be insufficient and the curing will be incomplete; if the amount is more than 5 parts, the excess initiator may remain in the electrode and affect the electrochemical performance. The preferred amount of radiation-sensitive initiator is 0.3 to 3 parts, more preferably 0.5 to 2 parts, for example, it can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, or 5.0 parts.

[0035] In this invention, the photoinitiator is used to absorb the visible light emitted by the X-ray long-afterglow luminescent material, generating free radicals through a photochemical reaction to initiate polymerization. In some embodiments, the photoinitiator is selected from at least one of anthraquinone compounds or thioxanthone compounds. Anthraquinone compounds, such as sodium anthraquinone-2-sulfonate, and thioxanthone compounds, such as 2-isopropylthioxanthone, have absorption wavelengths similar to Tb. 3+ The emission wavelength (approximately 544 nm) of the isoluminescent central ions is well matched. The amount of photoinitiator needs to be controlled within the range of 0.1 to 5 parts. If the amount is less than 0.1 parts, the photoinitiation efficiency is insufficient, and the curing reaction is incomplete; if the amount is more than 5 parts, excess initiator may remain in the electrode. The preferred amount of photoinitiator is 0.3 to 3 parts, more preferably 0.5 to 2 parts, for example, it can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, or 5.0 parts.

[0036] In this invention, the co-initiator is used to synergistically with the photoinitiator to improve the efficiency and rate of the photoinitiation reaction. The co-initiator itself does not directly absorb light energy, but promotes the generation of free radicals through electron transfer or hydrogen abstraction reactions with the excited-state photoinitiator. In some embodiments, the co-initiator is selected from at least one of amine compounds, alcohol compounds, or thiols. Amine compounds such as triethanolamine and methyldiethanolamine are commonly used hydrogen abstraction type co-initiators; alcohol compounds such as isopropanol; and thiols such as pentaerythritol tetra-3-mercaptopropionate can participate in polymerization through mercapto-olefin click reactions. Preferably, the co-initiator is triethanolamine.

[0037] The amount of co-initiator needs to be controlled within the range of 0.1 to 10 parts. If the amount is less than 0.1 parts, the promoting effect on the photoinitiation reaction is not obvious; if the amount is more than 10 parts, excess co-initiator may remain in the electrode. The preferred amount of co-initiator is 0.5 to 8 parts, more preferably 1 to 5 parts, for example, it can be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1.0 parts, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, 5.0 parts, 5.5 parts, 6.0 parts, 6.5 parts, 7.0 parts, 7.5 parts, 8.0 parts, 8.5 parts, 9.0 parts, 9.5 parts, or 10.0 parts.

[0038] In this invention, the X-ray long-afterglow luminescent material is a key functional component. After absorbing X-ray energy, it is excited to a high-energy state and continuously releases visible light of a specific wavelength through afterglow luminescence after irradiation ceases. This visible light can be absorbed by the photoinitiator in the system, thereby initiating a polymerization reaction and achieving "offline post-curing," compensating for insufficient curing in the irradiation shadow region. In some embodiments, the X-ray long-afterglow luminescent material is a rare-earth ion-doped fluoride with the general chemical formula AReF4:Ln. 3+ Where A is an alkali metal ion selected from Li + Na + K + One or more of the following; Re is a matrix rare earth ion selected from Y 3+ Lu 3+ Gd 3+ One or more of the following; Ln is the luminescent center rare earth ion selected from Tb 3+ Eu 3+ Ce 3+ One or more of the following. In one or more embodiments of the present invention, the X-ray long afterglow luminescent material is β-NaYF4:Tb 3+ Tb 3+ The doping molar concentration is 1% to 10%, for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, etc., and it can emit a green afterglow with a main peak of about 544 nm under X-ray excitation.

[0039] The amount of X-ray long-afterglow luminescent material should be controlled within the range of 0.01 to 5 parts. If the amount is less than 0.01 parts, the afterglow luminescence intensity will be insufficient, and the auxiliary curing effect will be limited; if the amount is more than 5 parts, excessive addition may affect the slurry dispersibility and electrode performance. The preferred amount of X-ray long-afterglow luminescent material is 0.05 to 3 parts, more preferably 0.1 to 2 parts, for example, it can be 0.01 parts, 0.02 parts, 0.03 parts, 0.04 parts, 0.05 parts, 0.08 parts, 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.2 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts, 4.5 parts, or 5.0 parts.

[0040] In some embodiments, the X-ray long-afterglow luminescent material can be obtained using rare-earth-doped luminescent material preparation methods known in the art, such as, but not limited to, hydrothermal methods, solvothermal methods, high-temperature solid-state methods, co-precipitation methods, or thermal decomposition methods. Taking the hydrothermal method as an example, it typically includes the following steps: preparing a rare-earth salt solution according to the target doping ratio, adding a complexing agent and a fluorine source, adjusting the pH value, and then transferring it to a high-pressure reactor for hydrothermal crystallization reaction. After the reaction, the material is centrifuged, washed, dried, and, if necessary, calcined at high temperature to obtain the X-ray long-afterglow luminescent material. By controlling parameters such as reaction temperature, time, and precursor concentration, the particle size, crystal phase, and luminescent properties of the material can be controlled. Those skilled in the art can select appropriate preparation methods and process conditions based on existing technical knowledge to prepare X-ray long-afterglow luminescent materials that meet the requirements of this invention.

[0041] The present invention also provides a method for preparing the above-mentioned positive electrode slurry, comprising the following steps: Under light-shielding conditions, the formulated amounts of phosphate-modified polyurethane acrylate oligomer, radiation-sensitive initiator, photoinitiator, co-initiator, and X-ray long afterglow luminescent material are added to a portion of the dispersion solvent and stirred until homogeneous to obtain a premixed solution. The positive electrode active material, conductive agent and binder in the prescribed amounts are mixed with the remaining dispersing solvent, stirred and dispersed to obtain the main material slurry; After mixing the premixed liquid and the main material slurry, the foam is removed to obtain the positive electrode slurry.

[0042] This invention premixes the photosensitive components (phosphate-modified polyurethane acrylate oligomer, radiation-sensitive initiator, photoinitiator, co-initiator, and X-ray long-afterglow luminescent material) under light-shielding conditions to prevent unnecessary premature reactions caused by ambient light during subsequent prolonged stirring, thus ensuring the preservation of their activity. Simultaneously, premixing the main slurry components (active substances, conductive agents, and binders) separately facilitates thorough dispersion of each component. Finally, mixing both ensures uniform distribution of the functional resin and initiation system throughout the slurry system, guaranteeing a uniform curing reaction.

[0043] In some embodiments, the mass of the dispersing solvent added to the premix is ​​20% to 40% of the total mass of the dispersing solvent, for example, 20%, 25%, 30%, 35%, or 40%. The stirring temperature is controlled at 25 to 40°C, for example, 25°C, 30°C, 35°C, or 40°C, and the stirring time is 30 to 90 minutes, for example, 30 minutes, 45 minutes, 60 minutes, 75 minutes, or 90 minutes. Light protection conditions can be achieved by using brown containers or operating in a dark room.

[0044] In some embodiments, the mixing of the positive electrode active material, conductive agent, and binder in the main slurry with the remaining dispersing solvent can be carried out using a vacuum mixer. The stirring speed can be 1000~1500 rpm, and the stirring time can be 60~120 minutes, for example 60 minutes, 80 minutes, 100 minutes, and 120 minutes.

[0045] In some embodiments, the mixing of the premix and the main slurry can be carried out in a vacuum mixer, with the stirring speed increased to 1500-2000 rpm and continuous stirring for 90-180 minutes, for example, 90 minutes, 120 minutes, 150 minutes, and 180 minutes. Subsequently, the vacuum system is turned on, with a vacuum degree ≤ -0.095 MPa, and degassing is performed at a lower speed of 500-800 rpm for 20-40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes, and 40 minutes, to obtain a stable, bubble-free positive electrode slurry. The final slurry viscosity can be controlled within the range of 3000-8000 mPa·s.

[0046] In some embodiments, the fineness of the positive electrode slurry is less than 30 μm, for example, it can be 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, or 28 μm. The fineness can be measured using a scraper fineness gauge.

[0047] The present invention also provides a positive electrode sheet, which is prepared from the above-described positive electrode slurry or the positive electrode slurry prepared by the above-described preparation method. Specifically, the positive electrode sheet includes a positive electrode current collector and a positive electrode slurry layer disposed on at least one surface of the positive electrode current collector.

[0048] The present invention also provides a method for preparing the above-mentioned positive electrode sheet, comprising the following steps: The positive electrode slurry is coated on the surface of the current collector, pre-dried, and then placed in an X-ray irradiation device for irradiation treatment. Finally, it is rolled to obtain the positive electrode sheet.

[0049] This invention achieves curing through X-ray irradiation, utilizing the high penetrating power of X-rays to ensure deep and uniform curing of thick coatings. Simultaneously, the X-ray irradiation process is rapid, significantly reducing curing time and improving production efficiency.

[0050] In some embodiments, the current collector is an aluminum foil with a thickness of 10-20 μm. Coating can be performed using a transfer coater or a comma roller coater. The coating thickness (single-sided) of the wet film is controlled by the die gap, ranging from 100 to 400 μm, for example, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, and 400 μm. For thick electrode fabrication, the coating thickness is preferably 200-400 μm.

[0051] In some embodiments, the preliminary drying can be carried out in a tunnel oven at a drying temperature of 90~130℃, such as 90℃, 105℃, 120℃, 125℃, 130℃, etc., with a conveyor speed of 1~3 m / min and a drying time of 5~15 minutes, such as 5 minutes, 8 minutes, 10 minutes, 12 minutes, 15 minutes. After preliminary drying, the electrode surface is basically dry, but still has a certain degree of stickiness, and most of the solvent has been removed.

[0052] In some embodiments, the irradiation treatment is performed in a dedicated X-ray irradiation device. The irradiation parameters are as follows: X-ray energy of 80–150 keV, for example, 80 keV, 90 keV, 100 keV, 110 keV, 120 keV, 130 keV, 140 keV, or 150 keV; radiation dose rate of 50–200 Gy / s, for example, 50 Gy / s, 80 Gy / s, 100 Gy / s, 120 Gy / s, 150 Gy / s, 180 Gy / s, or 200 Gy / s; and irradiation time of 10–60 seconds, for example, 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, or 60 seconds. The irradiation environment is preferably a nitrogen-protected environment, with an oxygen concentration preferably below 100 ppm, to suppress the inhibitory effect of oxygen on free radical polymerization and improve curing efficiency and degree of curing.

[0053] In some embodiments, the irradiated and cured electrode sheet can be further subjected to vacuum secondary drying to completely remove residual solvent. The secondary drying temperature can be 120~130°C, and the time can be 2~4 hours.

[0054] In some embodiments, the rolling is performed using a roller mill, with a rolling temperature of 80-100°C and a rolling pressure of 20-60 MPa, to achieve a predetermined compaction density for the electrode. For lithium iron phosphate cathodes, the compaction density can be controlled at 2.2-2.6 g / cm³. 3 For the high-nickel ternary cathode NCM811, the compaction density can be controlled between 3.3 and 3.6 g / cm³. 3 After rolling, the electrode sheet is slit to obtain the final positive electrode sheet.

[0055] The present invention also provides a lithium battery, comprising the above-described positive electrode sheet or the positive electrode sheet prepared by the above-described preparation method. The lithium battery further comprises a negative electrode sheet, a separator, an electrolyte, and a battery casing, wherein the separator is located between the positive electrode sheet and the negative electrode sheet.

[0056] In some embodiments, the negative electrode sheet includes a negative electrode current collector and a negative electrode slurry layer disposed on at least one surface of the negative electrode current collector. The negative electrode current collector may be selected from copper foil. The negative electrode active material may be selected from one or more of artificial graphite, natural graphite, silicon-carbon composite materials, silicon-oxygen composite materials, etc. The negative electrode binder may be selected from styrene-butadiene rubber, sodium carboxymethyl cellulose, polyacrylic acid, etc.

[0057] In some embodiments, the diaphragm comprises a polyolefin porous substrate, such as a polyethylene or polypropylene microporous membrane, the surface of which may be coated with a ceramic coating or a PVDF coating to improve thermal stability and adhesion to the electrode.

[0058] In some embodiments, the electrolyte comprises a lithium salt, an organic solvent, and an additive. The lithium salt may be selected from one or more of LiPF6, LiBF4, LiFSI, etc. The organic solvent may be selected from one or more of ethylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, etc. The additive may be selected from one or more of fluoroethylene carbonate, vinylene carbonate, 1,3-propanesulfonic acid lactone, etc.

[0059] The types of lithium batteries include, but are not limited to, prismatic stacked batteries, pouch stacked batteries, prismatic wound batteries, or cylindrical wound batteries, which can be selected according to actual application requirements.

[0060] The technical solution of the present invention will be further described below with reference to specific embodiments. The present invention does not impose any special restrictions on the source of reagents used in the following embodiments; commercially available products well known to those skilled in the art can be used.

[0061] In the following examples, the preparation method of phosphate-modified polyurethane acrylate oligomers is as follows: 20.0 g of polyether diol (Mn=1000, 0.020 mol) and 25 mL of ethyl acetate were added to a four-necked flask, N2 was bubbled through, and the temperature was raised to 80°C. 0.02 g of dibutyltin dilaurate (catalyst) was added. 4.2 g of diisocyanate (0.025 mol) was slowly added dropwise, controlling the temperature ≤85°C, and the addition was completed within 1 h. The reaction was maintained at this temperature for 2.5 h to obtain an NCO-terminated prepolymer with an NCO content of approximately 2.1 mmol / g. The temperature was lowered to 75°C, and 5.0 g of triethanolamine phosphate (TEPA-P, containing 3 free OH groups, 0.012 mol) was added. The reaction was carried out for 4 h, and the NCO content decreased to approximately 0.5 mmol / g, achieving phosphate grafting. The temperature was then lowered to 70℃, and 3.6 g of hydroxyacrylate (0.030 mol) and 0.01 g of hydroquinone were added dropwise over 2.5 h. The mixture was then kept at 80℃ for 3 h, with NCO < 0.05 mmol / g, yielding the acrylate-capped product. Finally, the solvent was removed under reduced pressure at 50℃ and 0.08 MPa, and the mixture was filtered to obtain a light yellow viscous oligomer, namely the phosphate-modified polyurethane acrylate oligomer. Its number-average molecular weight (Mn) was approximately 2500 g / mol, its weight-average molecular weight (Mw) was approximately 4500 g / mol, and its molecular weight distribution index (PDI) was 1.8.

[0062] In the following embodiments, the X-ray long afterglow luminescent material β-NaYF4:Tb 3+ The preparation method is as follows: Weigh 10.73 g (47.5 mmol) of Y₂O₃ and 0.93 g (1.25 mmol) of Tb₄O₇. 3+ The doping molar concentration was 5%. The solutions were dissolved separately in concentrated nitric acid, and excess nitric acid was removed by heating to prepare 0.5 mol / L nitrate solutions. The two solutions were mixed, and 16.0 g of sodium citrate was added as a complexing agent. The mixture was stirred for 30 minutes. Separately, 8.8 g (210 mmol) of NaF was dissolved in 50 mL of deionized water and slowly added dropwise to the above mixed solution. The pH was adjusted to 9 with ammonia, and the mixture was stirred for 1 hour to obtain a milky white precursor solution. The precursor solution was transferred to a 200 mL polytetrafluoroethylene-lined high-pressure reactor, with a filling degree of 80%, and hydrothermally reacted at 200℃ for 24 hours. After the reaction, the mixture was allowed to cool naturally. The product was centrifuged at 10,000 rpm. The precipitate was washed four times alternately with deionized water and anhydrous ethanol, dried in a vacuum drying oven at 80℃ for 12 hours, and then calcined in a muffle furnace at 400℃ for 2 hours to obtain a white powdery β-NaYF4:Tb. 3+X-ray long-afterglow luminescent material. X-ray diffraction analysis confirmed that it is a hexagonal crystal phase, and transmission electron microscopy showed that the particle size is about 200~300 nm. Under X-ray excitation, it can emit a green afterglow with a main peak of 544 nm.

[0063] Example 1 This embodiment provides the preparation of a high-nickel ternary cathode sheet.

[0064] (1) Preparation of positive electrode slurry: By weight, weigh out 100 parts of lithium nickel cobalt manganese oxide (NCM811), 1.5 parts of conductive carbon black (Super P), 1.5 parts of multi-walled carbon nanotubes, 2.5 parts of polyvinylidene fluoride (PVDF, HSV900), 8 parts of phosphate-modified polyurethane acrylate oligomer, 1 part of radiation-sensitive initiator carbon tetrabromide (CBr4), 0.3 parts of photoinitiator sodium anthraquinone-2-sulfonate, 2.5 parts of co-initiator triethanolamine (TEA), and X-ray long afterglow luminescent material β-NaYF4:Tb. 3+ 1 part, and an appropriate amount of dispersing solvent N-methylpyrrolidone (NMP).

[0065] Under light-shielding conditions, phosphate-modified polyurethane acrylate oligomers, carbon tetrabromide, sodium anthraquinone-2-sulfonate, triethanolamine, and β-NaYF4:Tb 3+ Add 30% NMP (by mass) to the total NMP and stir at 400 rpm for 60 minutes at 30°C to obtain a premix. Add the remaining NMP, PVDF, conductive carbon black, and carbon nanotubes to a vacuum mixer and stir at 1200 rpm for 90 minutes. Then add NCM811 and continue stirring for 60 minutes to obtain the main slurry. Add the premix to the main slurry and stir at 1800 rpm for 120 minutes. Then turn on the vacuum system (vacuum degree ≤ -0.095 MPa) to degas for 30 minutes to obtain a positive electrode slurry with a viscosity of approximately 5000 mPa·s.

[0066] (2) Preparation of the positive electrode sheet: The aforementioned positive electrode slurry was uniformly coated onto the surface of a 12 μm thick aluminum foil current collector using a transfer coating machine, with the wet film thickness controlled at 150 μm. The coated electrode sheet was then placed in a tunnel oven and pre-dried for 4 minutes at 120°C and a conveying speed of 2 m / min. The electrode sheet was then transferred to an X-ray irradiation device for irradiation curing under nitrogen protection (oxygen concentration below 100 ppm). The irradiation parameters were: X-ray energy 100 keV, radiation dose rate 100 Gy / s, and irradiation time 30 seconds. After irradiation, the electrode sheet was vacuum dried at 120°C for 2 hours, and then rolled using a roller mill at 90°C and 30 MPa pressure to achieve a compaction density of 3.4 g / cm³. 3 Finally, the positive electrode sheet is obtained by cutting.

[0067] Figure 1 This is a schematic diagram of the preparation process in this embodiment.

[0068] Example 2 This embodiment provides the preparation of a lithium iron phosphate positive electrode sheet.

[0069] (1) Preparation of positive electrode slurry: By weight, weigh out 100 parts of lithium iron phosphate (LFP), 3 parts of conductive carbon black (Ketjenblack EC-600JD), 2.5 parts of polyvinylidene fluoride (PVDF), 12 parts of phosphate-modified polyurethane acrylate oligomer, 0.8 parts of radiation-sensitive initiator diphenyliodonium hexafluorophosphate, 0.5 parts of photoinitiator 2-isopropylthioxanthraquinone (ITX), 4.5 parts of co-initiator methyl diethanolamine (MDEA), and β-NaYF4:Tb, a long afterglow X-ray luminescent material. 3+ 1.5 parts, and an appropriate amount of NMP dispersant.

[0070] Under light-shielding conditions, phosphate-modified polyurethane acrylate oligomers, diphenyliodonium hexafluorophosphate, ITX, MDEA, and β-NaYF4: Tb 3+ Add 25% NMP (by mass) to the total NMP and stir at 500 rpm for 45 minutes at 35°C to obtain a premix. Add the remaining NMP, PVDF, and conductive carbon black to a vacuum mixer and stir at 1500 rpm for 60 minutes. Then add LFP and continue stirring for 90 minutes to obtain the main slurry. Add the premix to the main slurry and stir at 2000 rpm for 150 minutes, then degas for 25 minutes to obtain a positive electrode slurry with a viscosity of approximately 5000 mPa·s.

[0071] (2) Preparation of the positive electrode sheet: The above-mentioned positive electrode slurry was uniformly coated onto the surface of an aluminum foil with a thickness of 15 μm, and the wet film thickness was controlled to be 250 μm. The coated electrode was then initially dried at 125°C for 5 minutes. It was then cured by X-ray irradiation under nitrogen protection with the following parameters: energy 120 keV, dose rate 150 Gy / s, and irradiation time 45 seconds. After irradiation, it was vacuum dried at 130°C for 2 hours, and then rolled at 80°C and 25 MPa pressure to achieve a compaction density of 2.4 g / cm³. 3 The positive electrode sheet is obtained by cutting.

[0072] Comparative Example 1 This comparative example uses a conventional method to prepare the positive electrode sheet, that is, the same formulation as in Example 2, but without the addition of phosphate-modified polyurethane acrylate oligomer, radiation-sensitive initiator, photoinitiator, co-initiator and X-ray long afterglow luminescent material.

[0073] (1) Preparation of positive electrode slurry: Mix 100 parts of LFP, 3 parts of conductive carbon black, 2.5 parts of PVDF with an appropriate amount of NMP, and stir and disperse in a vacuum mixer to obtain a positive electrode slurry. Adjust the viscosity to about 5000 mPa·s.

[0074] (2) Preparation of the positive electrode sheet: The above slurry was coated on the surface of aluminum foil with a wet film thickness of 250 μm. It was then dried in an oven at 120°C for 2 hours for heat curing. Finally, it was rolled and cut under the same conditions as in Example 2 to obtain the positive electrode sheet.

[0075] Comparative Example 2 This comparative example demonstrates the preparation of a positive electrode using the traditional UV curing method.

[0076] (1) Preparation of positive electrode slurry: Weigh out the following components by weight: 100 parts lithium iron phosphate (LFP), 3 parts conductive carbon black (Ketjenblack EC-600JD), 2.5 parts polyvinylidene fluoride (PVDF), 12 parts phosphate-modified polyurethane acrylate oligomer, 1.5 parts ultraviolet photoinitiator 1-hydroxycyclohexylphenyl ketone (photoinitiator 184), 0.5 parts ultraviolet photoinitiator 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), and an appropriate amount of dispersing solvent NMP.

[0077] PVDF, conductive carbon black, and a portion of NMP were added to a vacuum mixer and stirred at 1200 rpm for 60 minutes. Then, LFP was added, and stirring continued for 90 minutes. Phosphate-modified polyurethane acrylate oligomer, photoinitiator 184, and TPO were dissolved in the remaining NMP and added to the above slurry. The mixture was stirred at 1800 rpm for 120 minutes, followed by degassing for 30 minutes to obtain a positive electrode slurry with a viscosity of approximately 5000 mPa·s.

[0078] (2) Preparation of the positive electrode sheet: The above-mentioned positive electrode slurry was uniformly coated onto the surface of an aluminum foil with a thickness of 15 μm, and the wet film thickness was controlled to be 250 μm. The coated electrode was initially dried at 125℃ for 5 minutes. Then, the electrode was placed in a UV curing device and irradiated for 120 seconds in an air atmosphere using a 1000 W high-pressure mercury lamp (main wavelength 365 nm) at a lamp distance of 10 cm. After irradiation, the electrode was vacuum dried at 130℃ for 2 hours, and then rolled using a roller mill at 80℃ and 25 MPa pressure to achieve a compaction density of 2.4 g / cm³. 3 The positive electrode sheet is obtained by cutting.

[0079] Comparative Example 3 The only difference between this comparative example and Example 2 is that the X-ray long afterglow luminescent material β-NaYF4:Tb is not added in step (1) of this comparative example. 3+ .

[0080] Comparative Example 4 The only difference between this comparative example and Example 2 is that the radiation-sensitive initiator carbon tetrabromide is not added in step (1) of this comparative example.

[0081] Test case The positive electrode sheets obtained in the above embodiments and comparative examples were subjected to performance tests, and then assembled into coin cells for electrochemical performance evaluation. The specific test methods are as follows: 1. Flexibility Test: Cut the positive electrode sheet into strips of 2 cm × 5 cm, fold them 180° along their length, and observe whether cracks or peeling appear on the coating surface at the fold. At the same time, use a bending tester to determine the minimum bending radius (mm) when the electrode sheet cracks. The smaller the bending radius, the better the flexibility.

[0082] 2. Peel strength test: Referring to GB / T 2792-2014 standard, the positive electrode sheet is fixed to the steel plate with double-sided tape. The coating and aluminum foil are peeled off using a universal tensile testing machine at a tensile speed of 100 mm / min in the 180° direction. The peel force is recorded and the peel strength (N / cm) is calculated.

[0083] 3. Observation of curing depth and uniformity: The cured positive electrode sheet is cut along the cross section using argon ion polishing technology, and the curing morphology of the coating from the surface to the interior is observed using a scanning electron microscope to determine whether there are uncured areas or delamination.

[0084] 4. Electrode resistivity test: The surface resistance of the positive electrode is measured using a four-probe resistance meter, and the volume resistivity (Ω·cm) is calculated to evaluate the integrity of the conductive network.

[0085] 5. Electrochemical Performance Testing: The electrodes prepared in the examples and comparative examples were cut into 12 mm diameter discs as positive electrodes, with lithium metal sheets as negative electrodes, Celgard 2400 separators, and 1 mol / L LiPF6 / EC+DEC+EMC (volume ratio 1:1:1) as electrolyte. CR2032 coin cells were assembled in an argon glove box. Charge-discharge tests were conducted at 25°C at a 0.1C rate, with a voltage range of 2.5–4.2 V (for Example 1) or 2.0–3.8 V (for Examples 2 and Comparative Examples 1–4). The initial discharge specific capacity (mAh / g) was calculated. Cycling tests were then performed at a 1C rate, and the capacity retention rate (%) after 100 cycles was recorded.

[0086] The test results are summarized in Tables 1 and 2.

[0087] Table 1. Performance test data of positive electrode sheet Test Project Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 180° folded appearance No cracks No cracks Severe cracking Coating peeling No cracks Micro cracks Minimum bending radius (mm) 2.5 2.0 >10 8.5 3.0 5.5 Peel strength (N / cm) 32 30 6 4 21 15 Curing depth / uniformity Completely uniform Completely uniform not applicable Surface hardened, interior sticky. Some areas were not fully cured. There are micro-defects at the bottom Electrode resistivity (Ω·cm) 0.85 0.92 1.20 1.35 1.02 1.15 Table 2 Battery performance test data Test Project First discharge specific capacity (mAh / g) Capacity retention rate after 100 cycles (%) Example 1 198 94.5 Example 2 158 96.2 Comparative Example 1 155 86.0 Comparative Example 2 153 82.5 Comparative Example 3 157 91.0 Comparative Example 4 156 88.5 As can be seen from the test results in Tables 1 and 2, Example 2 (the LFP system of this invention) performed excellently in all performance tests. The coating showed no cracks after a 180° fold, with a minimum bending radius of only 2.0 mm, indicating excellent electrode flexibility. The peel strength reached 30 N / cm, demonstrating a strong bond between the coating and the current collector. After curing, the coating was completely uniform from the surface to the interior, with no delamination or uncured areas, proving that X-ray irradiation combined with the composite initiation system of this invention achieved deep and uniform curing of the thick coating. The electrode resistivity was low (0.92 Ω·cm), and the conductive network was intact. In terms of electrochemical performance, the initial discharge specific capacity was normal (158 mAh / g), and the capacity retention rate after 100 cycles was as high as 96.2%, exhibiting good cycle stability.

[0088] Compared to Example 2, Comparative Example 1 used a conventional thermosetting method and did not add a flexible resin system. The electrode had poor flexibility, cracked severely after being folded 180°, and had a minimum bending radius greater than 10 mm; the peel strength was only 6 N / cm, and the coating was easy to peel off; after 100 cycles, the capacity retention dropped to 86.0%, indicating that simple thermosetting cannot meet the requirements of flexibility and cohesion for thick electrodes.

[0089] Comparative Example 2 used a traditional UV curing method. Although a flexible resin and a UV photoinitiator were added, the limited penetration of UV light meant that only the surface layer could be cured, leaving sticky, uncured areas inside. The peel strength was only 4 N / cm, and the coating peeled off when folded at 180°. The electrode resistivity increased to 1.35 Ω·cm, and the cycling performance deteriorated, with a capacity retention of only 82.5% after 100 cycles. This demonstrates the limitations of UV curing in thick electrode systems.

[0090] Comparative Example 3, without the addition of X-ray long-afterglow luminescent material, still used X-ray irradiation, but its peel strength (21 N / cm) was significantly lower than that of Example 2 (30 N / cm), and some areas showed incomplete curing after curing. This indicates that the long-afterglow luminescent material plays an indispensable role in this invention, compensating for insufficient curing in the irradiated shadow area through its afterglow luminescence effect, thus ensuring curing uniformity.

[0091] Comparative Example 4, without the addition of a radiation-sensitive initiator, retained both long-afterglow material and photoinitiator, but its peel strength (15 N / cm) further decreased, micro-defects were present at the bottom after curing, and its cycle stability (88.5%) was inferior to that of Example 2. This indicates that the radiation-sensitive initiator plays a crucial role in the direct X-ray initiation pathway, and the curing effect is insufficient without this component.

[0092] The test results of Example 1 (NCM system) show that the present invention is also applicable to high-nickel ternary systems, achieving excellent flexibility and electrochemical performance at medium coating thickness, proving that the present invention has broad applicability.

[0093] In summary, the present invention achieves rapid, uniform, and deep curing of thick electrode coatings by utilizing the synergistic effect of a composite initiation system consisting of X-ray long-afterglow luminescent materials, radiation-sensitive initiators, photoinitiators, and co-initiators, while simultaneously leveraging the direct radiochemical effect of X-rays and the indirect photochemical effect of long-afterglow materials. This significantly improves the flexibility, crack resistance, and electrochemical stability of the electrode sheet, demonstrating outstanding technical effects.

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A positive electrode slurry, characterized in that, By weight, it includes: 100 parts of positive electrode active material; 1-10 parts of conductive agent; 0.5 to 5 parts of adhesive; 1-20 parts of phosphate-modified polyurethane acrylate oligomer; 0.1 to 5 parts of radiation-sensitive initiator; Photoinitiator 0.1-5 parts; Total initiator: 0.1-10 parts; 0.01~5 parts of X-ray long afterglow luminescent material; Dispersing solvent.

2. The positive electrode slurry as described in claim 1, characterized in that, The number average molecular weight of the phosphate-modified polyurethane acrylate oligomer is 1500~8000 g / mol.

3. The positive electrode slurry as described in claim 1, characterized in that, The radiation-sensitive initiator is selected from at least one of halogenated compounds, iodonium salts, sulfonium salts, or metallocene compounds; the photoinitiator is selected from at least one of anthraquinone compounds or thioxanthone compounds; and the co-initiator is selected from at least one of amine compounds, alcohol compounds, or thiols.

4. The positive electrode slurry as described in claim 3, characterized in that, The halogenated compound is carbon tetrabromide, the iodonium salt is diphenyliodonium hexafluorophosphate, the metallocene compound is ferrocene, the amine compound is triethanolamine or methyldiethanolamine, the alcohol compound is isopropanol, and the thiol compound is pentaerythritol tetra-3-mercaptopropionate.

5. The positive electrode slurry as described in claim 1, characterized in that, The X-ray long afterglow luminescent material is a rare-earth ion-doped fluoride with the general chemical formula AReF4:Ln 3+ Where A is an alkali metal ion selected from Li + Na + K + One or more of the following; Re is a matrix rare earth ion selected from Y 3+ Lu 3+ Gd 3+ One or more of the following; Ln is the luminescent center rare earth ion selected from Tb 3+ Eu 3+ Ce 3+ One or more of them.

6. The method for preparing the positive electrode slurry according to any one of claims 1 to 5, characterized in that, Includes the following steps: Under light-shielding conditions, phosphate-modified polyurethane acrylate oligomer, radiation-sensitive initiator, photoinitiator, co-initiator, and X-ray long afterglow luminescent material are added to a portion of the dispersion solvent and stirred until homogeneous to obtain a premixed solution. The positive electrode active material, conductive agent, and binder are mixed with the remaining dispersing solvent and stirred to disperse, thus obtaining the main material slurry. The premixed liquid and the main material slurry are mixed and then degassed to obtain the final product.

7. A positive electrode sheet, characterized in that, It is prepared from the positive electrode slurry according to any one of claims 1 to 5 or the positive electrode slurry prepared by the preparation method according to claim 6.

8. The method for preparing the positive electrode sheet as described in claim 7, characterized in that, Includes the following steps: The positive electrode slurry is coated on the surface of the current collector, pre-dried, and then placed in an X-ray irradiation device for irradiation treatment. Finally, it is rolled to obtain the positive electrode sheet.

9. The preparation method according to claim 8, characterized in that, The parameters for the irradiation treatment are as follows: X-ray energy of 80~150 keV, radiation dose rate of 50~200 Gy / s, and irradiation time of 10~60 seconds.

10. A lithium battery, characterized in that, This includes the positive electrode sheet as described in claim 7 or the positive electrode sheet prepared by the preparation method described in claim 8 or 9.

Images