An electrode tab prepared by ectopic polymerization and a preparation method thereof, a separator-free battery, and a solid-state battery

Abstract

This invention belongs to the field of battery technology and discloses an electrode prepared by heterospatial polymerization and its preparation method, a separatorless battery, and a solid-state battery. The method for preparing the electrode by heterospatial polymerization includes: mixing a monomer and an initiator to perform a first polymerization to obtain a prepolymer precursor solution; introducing the prepolymer precursor solution into at least one side of a current collector to perform a second polymerization to form an interfacial flexible layer on at least one side of the current collector. The electrode prepared using the method provided in this application can improve the cycle stability, initial coulombic efficiency, and safety performance of the battery.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to an electrode prepared by heterospatial polymerization and its preparation method, a solid-state battery, and a membraneless battery. Background Technology

[0002] Lithium-ion batteries are widely used in portable electronic products, electric vehicles, and energy storage due to their high energy density and excellent rate performance. At the same time, these devices place increasingly higher demands on the lifespan, high-temperature performance, energy density, and safety of lithium-ion batteries. As battery operating voltage and energy density increase, the thermal stability of the battery electrodes deteriorates, making them prone to thermal runaway under extreme conditions, which can lead to battery combustion or even explosion.

[0003] Currently, in lithium-ion batteries, solid polymer electrolytes offer good processability and flexibility, providing excellent interfacial contact between the electrode and the solid electrolyte. However, during electrode composite processing, the polymerization process is difficult to control, and numerous side reactions occur, leading to uneven polymerization and increased interfacial impedance. This, in turn, affects the battery's cycle performance, initial coulombic efficiency, and safety performance. Summary of the Invention

[0004] This invention aims to at least partially solve one of the technical problems in related technologies. Therefore, one object of this invention is to provide an electrode prepared by heterospatial polymerization and its preparation method, a separatorless battery, and a solid-state battery. The electrode prepared using the method provided in this application can improve the cycle stability, initial coulombic efficiency, and safety performance of the battery.

[0005] In a first aspect, the present invention provides a method for preparing electrode sheets by ex-situ polymerization. According to an embodiment of the present invention, the method includes: mixing a monomer and an initiator to perform a first polymerization to obtain a prepolymer precursor liquid; introducing the prepolymer precursor liquid into at least one side of a current collector and performing a second polymerization to form an interfacial flexible layer on one side of the current collector.

[0006] According to the method of the above embodiments of the present invention, using heterospatial polymerization technology, the heterospatial polymerization process of monomers can be controlled through the first polymerization reaction, ensuring stable polymerization and improving product quality consistency. Furthermore, by employing electrode composite and interface softening technologies, all-solid-state battery electrodes can be constructed in one step, simplifying the production process and improving production efficiency. Compared to traditional multi-step preparation methods, this one-step construction method reduces errors and losses that may arise from intermediate steps, ensuring the quality and performance stability of the electrode. This one-step construction method enables the prepolymer precursor liquid to achieve highly dispersed and uniform distribution both inside and on the surface of the electrode. Inside the electrode, the uniform distribution of the prepolymer precursor liquid improves the structural stability and ion transport performance of the active material. On the surface, the uniformly distributed prepolymer precursor liquid improves contact with the solid electrolyte, reduces interfacial impedance, promotes ion transport, and constructs an ion / electron transport pathway. The ion transport pathway ensures rapid migration of lithium ions between the electrode and the solid electrolyte, improving the battery's charge / discharge efficiency and rate performance. The electron transport pathway ensures efficient electron transport within the electrode and in the external circuitry, reducing battery internal resistance and improving energy conversion efficiency.

[0007] Furthermore, the interface softening through the flexible interface layer can improve the problem of poor solid-solid contact, reduce interface impedance, and thus improve ion transport efficiency. It can also alleviate interface stress caused by volume changes during battery charging and discharging, enhancing the stability of the electrode structure and thereby improving the battery's cycle stability. In addition, since the active material in the electrode releases oxygen when operating at high voltage, interface softening can suppress oxygen release, thereby improving the battery's thermal stability and safety. Under the action of the initiator, monomers undergo polymerization reactions, forming a uniform polymer matrix in the flexible interface layer. Through ex-situ polymerization, high-flux ion transport channels can be constructed during electrode composite processes, achieving high dispersion of monomers, forming a uniform polymer matrix, and achieving uniform distribution within the electrode, thereby enhancing the stability of the electrode structure and significantly improving battery safety. The flexible interface layer covering the electrode reduces the specific surface area of ​​the active material layer, resulting in a smoother SEI film formed during the first charge and discharge, reducing side reactions, and effectively improving the battery's first coulombic efficiency. Therefore, the electrode prepared using the method provided in this application can improve the battery's cycle stability, first coulombic efficiency, and safety performance.

[0008] In addition, the method according to the above embodiments of the present invention may also have the following additional technical features:

[0009] In some embodiments of the present invention, before the step of mixing the monomer and the initiator to perform a first polymerization to obtain the prepolymer precursor liquid, the method further includes: preparing an active material layer on at least one side of the current collector. This improves the battery's cycle stability, initial coulombic efficiency, and safety performance.

[0010] In some embodiments of the present invention, after the steps of mixing the monomer and initiator to perform a first polymerization to obtain a prepolymer precursor liquid, and before the steps of introducing the prepolymer precursor liquid to at least one side of the current collector and performing a second polymerization to form an interfacial flexible layer on one side of the current collector, the method further includes: mixing the prepolymer precursor liquid with an active material. This improves the battery's cycle stability, initial coulombic efficiency, and safety performance.

[0011] In some embodiments of the present invention, the active material includes one of a positive electrode active material and a negative electrode active material. This is beneficial for improving the initial coulombic efficiency, cycle stability, and safety performance of the battery.

[0012] In some embodiments of the present invention, the positive electrode active material includes at least one of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium vanadium phosphate, and lithium-rich manganese-based materials.

[0013] In some embodiments of the present invention, the negative electrode active material includes at least one of graphite, graphene, soft carbon, hard carbon, elemental silicon, silicon-oxygen materials, silicon-carbon materials, silicon-nitrogen composite materials, silicon-based alloys, elemental tin, tin oxides, tin-based alloys, lithium metal, lithium alloys, lithium titanium oxides, transition metal oxides, and transition metal sulfides.

[0014] In some embodiments of the present invention, the degree of polymerization of the prepolymer precursor liquid is 5%-60%. Therefore, the prepolymer maintains a certain degree of fluidity, ensuring that the prepolymer precursor liquid can smoothly enter the electrode and solidify within it, reducing defects and porosity within the electrode, preventing micro-short circuits, and blocking direct contact between the positive and negative electrodes, thereby preventing large-area short circuits and improving battery safety and cycle stability.

[0015] In some embodiments of the present invention, the viscosity of the prepolymer precursor liquid is η, where η satisfies: 0 < η ≤ 1000 Pa·s. Therefore, the prepolymer precursor liquid has good fluidity and permeability, allowing it to more easily penetrate the interior of the electrode after being introduced onto the electrode surface, fully filling the pores and structure inside the electrode, thereby enhancing the stability and integrity of the electrode and improving the safety performance and cycle stability of the battery.

[0016] In some embodiments of the present invention, the step of mixing the monomer and initiator to perform a first polymerization to obtain a prepolymer precursor liquid includes: mixing the monomer, lithium salt, inorganic filler, conductive agent, crosslinking agent, initiator and solvent, and then performing a first polymerization to obtain a prepolymer precursor liquid. This can improve the initial coulombic efficiency, cycle performance and safety performance of the battery.

[0017] In some embodiments of the present invention, the monomer accounts for 0.5%-30% of the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent. This enables an effective polymerization reaction under the action of the initiator, helping to ensure the controllability of the polymerization process. This, in turn, optimizes the performance of the interface flexible layer, allowing it to better improve solid-solid contact, prevent micro-short circuits and large-area short circuits, thereby enhancing the cycle stability and safety performance of the solid-state battery.

[0018] In some embodiments of the present invention, the monomer includes at least one of acrylate monomers, acrylonitrile monomers, cycloolefin monomers, vinylene monomers, amide monomers, alkyl sulfides, sulfate monomers, borate ester monomers, cyanamide monomers, and quaternary ammonium salt monomers.

[0019] In some embodiments of the present invention, the mass ratio of the lithium salt is 0.5%-30% based on the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent. This ensures smooth ion conduction, improves ionic conductivity, thereby enhancing the battery's charge-discharge performance and simultaneously extending the battery's electrochemical stability window. This allows the battery to operate within a more stable voltage range during charge-discharge, reducing side reactions and improving cycle life and safety.

[0020] In some embodiments of the present invention, the inorganic filler accounts for 5%-50% of the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent. This helps to disperse and conduct heat, reducing localized overheating, thereby lowering the risk of thermal runaway and improving battery safety and cycle performance.

[0021] In some embodiments of the present invention, the initiator accounts for 0.1%-3% of the monomer mass. Thus, it works synergistically with other components such as monomers, lithium salts, inorganic fillers, conductive agents, and crosslinking agents to jointly construct a stable polymer matrix structure, which helps optimize the performance of the polymer matrix, improve the overall performance of the electrode, and consequently enhance the cycle stability and safety performance of the battery.

[0022] In some embodiments of the present invention, the D50 particle size of the conductive agent is 5nm-1000nm, preferably 10nm-500nm. This results in better dispersibility of the conductive agent, allowing it to be more uniformly distributed within the polymer matrix formed by monomer polymerization. Uniform distribution ensures uniform current conduction within the electrode, avoiding hot spots and performance degradation caused by excessive local current, and improving the cycle stability of the battery.

[0023] In some embodiments of the present invention, the D50 particle size of the inorganic filler is 2nm-500nm, preferably 10nm-300nm. This allows for more uniform dispersion within the polymer matrix, better interaction with the polymer matrix and other components, improved interfacial properties, reduced interfacial impedance, enhanced interfacial smoothness, promoted ion and electron transport, and improved electrochemical performance of the battery.

[0024] In some embodiments of the present invention, the inorganic filler includes at least one of inorganic active filler and inorganic inert filler.

[0025] In some embodiments of the present invention, the inorganic active filler includes at least one of oxide active filler, sulfide active filler, halide active filler, nitride active filler, boride active filler and hydride active filler.

[0026] In some embodiments of the present invention, the inorganic inert filler includes at least one of oxide inert fillers, nitride inert fillers, boride inert fillers, halide inert fillers, dielectric ceramic inert fillers, ferroelectric ceramic inert fillers, piezoelectric ceramic inert fillers, diatomaceous earth inert fillers, mullite inert fillers, montmorillonite inert fillers, and kaolin inert fillers.

[0027] In some embodiments of the present invention, the first polymerization method includes at least one of thermal polymerization, photopolymerization, and ultrasonic polymerization.

[0028] In some embodiments of the present invention, the first polymerization method includes heated ultrasonic polymerization, which combines thermal polymerization and ultrasonic polymerization. This improves the battery's safety performance, cycle performance, and initial coulombic efficiency.

[0029] In some embodiments of the present invention, the temperature for the ultrasonic polymerization is 30°C-100°C, preferably 40°C-60°C. This provides the energy required for the reaction, making it easier for molecules in the reaction system to collide and react, thereby increasing the rate and efficiency of the polymerization reaction.

[0030] In some embodiments of the present invention, the frequency of the heating and ultrasonic polymerization is 0.5MHz-5.0MHz. This improves the battery's safety performance, cycle performance, and initial coulombic efficiency.

[0031] In some embodiments of the present invention, the heating and ultrasonic polymerization time is 1-12 hours. This improves the uniformity of the polymer matrix, and the good dispersibility reduces interfacial impedance, enhances interfacial smoothness, promotes the effective transport of lithium ions in the ceramic phase, ceramic-polymer interface, and intervention pathways, improves ionic conductivity and electrochemical stability window, and helps improve the charge-discharge performance, cycle life, and safety of the battery.

[0032] In some embodiments of the present invention, the temperature of the second polymerization is 40°C-120°C. This provides sufficient energy for the second polymerization, accelerates the polymerization reaction of the monomers, controls the degree of the second polymerization, and enables better bonding between the prepolymer precursor liquid and the active material, forming a stable active material layer and an interface flexible layer. This reduces the shedding and deformation of the active material during charging and discharging, improving the cycle life and safety of the battery.

[0033] In some embodiments of the present invention, the second polymerization time is 10s-2min. This allows for precise control of the degree of the second polymerization, contributing to the formation of a uniform and stable active material layer and interface flexible layer. It also reduces the shedding and deformation of active material during charging and discharging, thereby improving the battery's cycle life and safety.

[0034] In some embodiments of the present invention, the method of introduction includes at least one of coating, spraying, and impregnation.

[0035] In some embodiments of the present invention, the introduction method includes coating, specifically gravure coating. This allows for precise control of the coating thickness and uniformity, achieving a uniform coating effect and ensuring consistent distribution of the active material and prepolymer precursor liquid on the current collector.

[0036] In some embodiments of the present invention, the gravure coating speed is 0.5 m / min to 10 m / min. This improves battery consistency and reliability, reduces problems caused by localized performance differences, and enhances battery safety and cycle stability.

[0037] In some embodiments of the present invention, the tension of the gravure coating is 30N-200N. This increases the adhesion between the current collector and the coating; the tension ensures close contact between the current collector and the gravure roller, which helps the coating adhere better to the current collector, improving battery reliability and cycle stability.

[0038] In some embodiments of the present invention, the coating thickness of the gravure coating is 0.5 μm-3 μm. This ensures the loading of active material while maintaining the stability of the electrode structure, thus balancing the mechanical strength and ion transport performance of the electrode to a certain extent and extending the cycle life of the battery.

[0039] In some embodiments of the present invention, the method further includes preparing a solid electrolyte layer on the flexible interface layer. This facilitates rapid migration of lithium ions between the positive and negative electrodes, improving the charge-discharge performance of the battery. Compared to traditional liquid electrolytes, solid electrolytes reduce the risk of leakage and enhance battery safety.

[0040] In a second aspect, the present invention provides an electrode prepared by ex-situ polymerization. According to embodiments of the present invention, the electrode prepared by ex-situ polymerization comprises electrodes prepared using the method of the first aspect. This electrode prepared by ex-situ polymerization can improve the cycle stability, initial coulombic efficiency, and safety performance of the battery.

[0041] In a third aspect, the present invention provides a separatorless battery. According to embodiments of the invention, the separatorless battery comprises electrodes prepared using the method of the first aspect or including the electrode preparation via ex-situ polymerization as described in the second aspect. This separatorless battery exhibits excellent safety performance, cycle performance, and initial coulombic efficiency.

[0042] In a fourth aspect, the present invention provides a solid-state battery. According to embodiments of the invention, the solid-state battery is prepared using the method of the first aspect or includes electrodes prepared by the heterospatial polymerization method of the second aspect. This solid-state battery exhibits excellent safety performance, cycle performance, and initial coulombic efficiency.

[0043] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0044] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0045] Figure 1 This diagram shows a battery structure prepared by an electrode using heterospatial polymerization according to an embodiment of the present invention.

[0046] Icon labels:

[0047] Electrode 10 prepared by heterostomosis polymerization, current collector 1, active material layer 2, interface flexible layer 3, solid electrolyte layer 4. Detailed Implementation

[0048] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0049] In a first aspect, the present invention provides a method for preparing electrode sheets by ex-situ polymerization. According to embodiments of this application, the method includes:

[0050] S1. Mix the monomer and initiator to carry out the first polymerization to obtain the prepolymer precursor liquid.

[0051] In this step, by mixing the monomer and the initiator and then performing the first polymerization, a prepolymer precursor liquid can be obtained.

[0052] It should be noted that ex-situ polymerization refers to a method in which a prepolymer precursor solution is obtained through a first polymerization, and then introduced into a current collector for a second polymerization to form an electrode. By using ex-situ polymerization technology, the first polymerization reaction can achieve controllable ex-situ polymerization of monomers, ensuring stable polymerization and improving product quality consistency. Furthermore, by employing electrode composite and interface softening technologies, all-solid-state battery electrodes can be constructed in one step, simplifying the production process and improving production efficiency. Therefore, the electrode preparation technology of this invention, when applied to lithium batteries, improves the penetration into the microporous structure of the cell and the uniformity of polymer macroscopic distribution within the battery, solving the problems of uneven polymerization and wetting during in-situ solidification. Batteries prepared by this method have high ionic conductivity and electrochemical stability window, high mechanical strength and stable cycle performance, as well as excellent safety performance. Moreover, this method is low-cost, highly efficient, effectively controls product consistency, and has a stable yield, which is conducive to large-scale production and development.

[0053] According to some embodiments of the present invention, the degree of polymerization of the prepolymer precursor liquid is 5%-60%. For example, it can be 5%, 10%, 20%, 40%, 60%, etc. By limiting the degree of polymerization of the prepolymer precursor liquid within the above range, the prepolymer can maintain a certain fluidity, ensuring that the prepolymer precursor liquid can smoothly enter the interior of the electrode (active material layer) and solidify within the electrode, reducing defects and porosity inside the electrode, preventing micro-short circuits, and preventing direct contact between the positive and negative electrodes, thereby preventing large-area short circuits and improving the safety performance and cycle stability of the battery.

[0054] It should be noted that the degree of polymerization in the prepolymer precursor solution specifically represents the relative relationship between the actual molecular weight of the polymer and its theoretically achievable maximum molecular weight. Presented as a percentage, it allows us to intuitively understand the degree of polymer growth and how close it is to its maximum size.

[0055] According to some embodiments of the present invention, the viscosity of the prepolymer precursor liquid is η, where η satisfies: 0 < η ≤ 1000 Pa·s. For example, it can be 1 Pa·s, 10 Pa·s, 100 Pa·s, 500 Pa·s, 1000 Pa·s, etc. By limiting the viscosity of the polymer precursor to the above range, the prepolymer precursor liquid has good fluidity and permeability, allowing it to more easily penetrate into the interior of the electrode after being introduced onto the electrode surface, thereby enhancing the stability and integrity of the electrode. Furthermore, the prepolymer precursor liquid has a certain viscosity, which ensures that the internal components maintain a high dispersion effect over a long period of time, resulting in uniform dispersion when coated on the electrode, reducing the specific surface area of ​​the electrode, and forming a smooth SEI or CEI, which is beneficial for improving the battery's safety performance, coulombic efficiency, and cycle stability.

[0056] The method of the first polymerization is not specifically limited. For example, the method of the first polymerization includes, but is not limited to, at least one of thermal polymerization, photopolymerization and ultrasonic polymerization. Those skilled in the art can make a flexible choice as needed.

[0057] According to a specific embodiment of the present invention, the first polymerization method includes heated ultrasonic polymerization, which combines thermal polymerization and ultrasonic polymerization. Thermal polymerization provides energy to promote the polymerization reaction of monomers; ultrasonic polymerization enhances molecular collision and reactivity through the cavitation and mechanical effects of ultrasound, thereby improving polymerization efficiency. Furthermore, ultrasonic polymerization enables monomers and inorganic fillers to achieve highly dispersed distribution in solution, promoting uniform distribution of the material through in-situ polymerization, helping to reduce the inhomogeneity of the polymerization products, and improving the consistency and stability of the material. The uniform distribution of polymers and the presence of inorganic materials can improve interfacial contact performance, reduce interfacial defects and charge accumulation, thereby reducing interfacial impedance and helping to improve ion and electron transport efficiency, thus increasing the battery's initial coulombic efficiency. The uniform dispersion of inorganic materials in the polymer matrix formed by monomer polymerization can reduce agglomeration, resulting in a smoother interface. A smooth interface helps to reduce charge concentration and electric field distortion, improving the battery's cycle stability. The first polymerization allows the inorganic materials to better integrate with the polymer matrix formed by monomer polymerization, forming a stable structure, which helps to enhance the mechanical properties of the interfacial softening layer, improve its resistance to external forces and deformation, and enhance the battery's cycle performance. Furthermore, ultrasonic polymerization can also adjust the microstructure of materials and promote Li + Efficient ion transport across the ceramic phase, ceramic-polymer interface, and intervention pathways contributes to improved ionic conductivity and enhanced battery charge-discharge performance. This, in turn, improves battery safety, cycle performance, and initial coulombic efficiency.

[0058] According to some embodiments of the present invention, the temperature for ultrasonic polymerization is 30°C-100°C. For example, it can be 30°C, 50°C, 70°C, 90°C, 100°C, etc. By limiting the ultrasonic polymerization temperature within the above range, the energy required for the reaction can be provided, making it easier for molecules in the reaction system to collide and break chemical bonds, thereby improving the rate and efficiency of the polymerization reaction. According to other embodiments of the present invention, the ultrasonic polymerization temperature is preferably 40°C-60°C, for example, 40°C, 50°C, 60°C, etc.

[0059] According to some embodiments of the present invention, the frequency of the ultrasonic polymerization is 0.5 MHz to 5.0 MHz. For example, it can be 0.5 MHz, 1 MHz, 2 MHz, 3 MHz, 4 MHz, 5 MHz, etc. By limiting the frequency of ultrasonic polymerization within the above range, ultrasound can generate strong vibration and cavitation effects, which helps to promote the dispersion and uniform mixing of components such as monomers, initiators, lithium salts, inorganic fillers, conductive agents, and crosslinking agents, achieving a high dispersion distribution. This promotes the uniform distribution of heterogeneous polymerization of each component material, helps to reduce the inhomogeneity of the polymerization product, and improves the consistency and stability of the material. The presence of uniformly distributed polymers and inorganic materials can improve the contact performance of the interface, reduce interface defects and charge accumulation, thereby reducing interface impedance, helping to improve the ion and electron transport efficiency, and enhancing the safety performance of the battery's first coulombic efficiency. The uniform dispersion of inorganic materials in the polymer matrix of monomer polymerization can reduce agglomeration, thereby making the solid-solid contact interface smoother. A smooth interface is conducive to reducing charge concentration and uniform lithium deposition, suppressing lithium dendrite formation, and improving the cycle stability of the battery. Thus, the safety performance, cycle performance, and first coulombic efficiency of the battery can be improved.

[0060] According to some embodiments of the present invention, the time for ultrasonic polymerization is 1-12 hours. For example, it can be 1 hour, 3 hours, 5 hours, 10 hours, 12 hours, etc. By limiting the ultrasonic polymerization time within the above range, on the one hand, sufficient time can be given for the monomer to undergo the polymerization reaction, ensuring that the monomer is fully converted into polymer, increasing the degree of polymerization, and making the structure of the polymer matrix formed by monomer polymerization more stable and complete. This is conducive to the formation of a uniform polymer network, enhancing the mechanical properties and stability of the material, and thus improving the cycle performance of the battery. On the other hand, it can promote better dispersion of inorganic materials and conductive agents in the polymer matrix formed by monomer polymerization, helping to break the agglomeration of inorganic materials and conductive agents, so that they are uniformly distributed in the polymer, improving the performance uniformity of the polymer matrix formed by monomer polymerization. Good dispersion can reduce interfacial impedance, improve interfacial smoothness, promote the effective transport of lithium ions in the ceramic phase, ceramic-polymer interface and intervention path, improve ionic conductivity and electrochemical stability window, and help improve the charge-discharge performance, cycle life and safety of the battery.

[0061] It should be noted that there are no special restrictions on the types of monomers and initiators, and those skilled in the art can make flexible choices as needed.

[0062] As an example, the monomer includes monomers with high ionic and electronic conductivity, such as monomers including but not limited to at least one of acrylate monomers, acrylonitrile monomers, cycloolefin monomers, vinylene monomers, amide monomers, alkyl sulfides, sulfate monomers, borate ester monomers, cyanamide monomers, and quaternary ammonium salt monomers.

[0063] As an example, the monomers include ethylene glycol methacrylate, ethylene glycol diacrylate, vinylene carbonate, vinylidene fluoride, tetrafluoroethylene, propylene carbonate polyvinylidene fluoride, acrylonitrile, ethylene oxide, vinylidene fluoride-hexafluoropropylene, hexafluoropropylene, lactam, dioxolane, dithiopentane, thioctic acid, cyclothioalkylene, alkyl disulfides, tetramethylphosphine chloride, melamine, alkenylated monophosphine ligands, bisphosphine ligands, arginine methyl ester, arginine ethyl ester, methoxy polyethylene glycol, isonitrile, quaternary ammonium salt monomers, and cycloboroxane. At least one of the following: trifluoromethylphenylboronic acid methyliminodiacetic acid, phthalic acid diacrylate, pentaerythritol tetraacrylate, methacrylate, methacryloyloxyethyl ester, ethylene glycol acrylate, pentaerythritol acrylate, ethylene glycol methacrylate, ethylene glycol dimethacrylate, ethylene glycol dimethyl ether vinyl sulfite, trithiocarbonate vinylidene, 1,3-propenyl-sulfonate lactone, ethyl vinyl sulfone, vinyl acetate, acrylamide, 1,3-dioxolane, and 1,4-dioxane.

[0064] As an example, the initiator includes at least one of 2,2'-azobis(isobutyronitrile), benzoyl peroxide, azobisisoheptanenitrile, diethylhexyl peroxide dicarbonate, dimethyl azobisisobutyrate, benzoyl oxide, tert-butyl peroxide, methyl ethyl ketone peroxide, mercaptobenzene, thiols, and alkyl thiols.

[0065] According to some embodiments of the present invention, the step of mixing monomers and initiators and performing a first polymerization to obtain a prepolymer precursor liquid includes: mixing monomers, lithium salts, inorganic fillers, conductive agents, crosslinking agents, initiators, and solvents, and then performing a first polymerization to obtain a prepolymer precursor liquid. Monomers are the basis for polymer formation, constructing the polymer matrix through polymerization reactions, providing structural support and certain physicochemical properties for the electrode. In the battery system, the main role of lithium salts is to provide lithium ions, ensuring sufficient lithium ion transport during charging and discharging, thereby achieving the battery's electrochemical performance. Inorganic fillers can improve the mechanical strength and thermal stability of the electrode, synergistically working with the polymer matrix to improve ion transport efficiency in the electrode. Conductive agents can form a conductive network between active materials, promoting electron transport, reducing the battery's internal resistance, and improving the battery's charge / discharge performance and rate performance. Crosslinking agents promote crosslinking reactions between polymer molecules, enabling the polymer to form a three-dimensional network structure. Initiators initiate the polymerization reaction of monomers to form the polymer. Solvents can dissolve the components, allowing them to be fully and uniformly mixed. By mixing the above components and carrying out the first polymerization, a prepolymer precursor liquid with a certain molecular weight and reactivity can be obtained, which provides a basis for the subsequent second polymerization, enabling the second polymerization to form a polymer matrix and a flexible interfacial layer in the active material layer.

[0066] According to some embodiments of the present invention, the prepolymer precursor liquid is further provided with a binder, which includes, but is not limited to, at least one of polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), polypropylene, polyethylene, polyvinylidene fluoride (PVDF), SBR rubber, fluorinated rubber, polyurethane, polyamide, sodium carboxymethyl cellulose (CMC), and polyacrylic acid.

[0067] According to some embodiments of the present invention, based on the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent, the mass percentage of the monomer is 0.5%-30%. For example, it can be 0.5%, 1%, 5%, 10%, 20%, 30%, etc. By limiting the mass percentage of the monomer within the above range, an effective polymerization reaction can be carried out under the action of the initiator, which helps to ensure the controllability of the polymerization process, avoids excessive monomer leading to low mechanical strength of the polymer matrix, and prevents the inorganic filler from being incorporated, thus reducing the occurrence of side reactions in the system; at the same time, it also prevents insufficient monomer, resulting in insufficient polymerization products and failure to form an effective polymer matrix, thereby optimizing the performance of the interface flexible layer, enabling it to better play its role in improving poor solid-solid contact, preventing micro-short circuits and large-area short circuits, thereby improving the cycle stability and safety performance of solid-state batteries.

[0068] According to some embodiments of the present invention, the mass ratio of the lithium salt is 0.5%-30% based on the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent. For example, it can be 0.5%, 1%, 5%, 10%, 20%, 30%, etc. The addition of the lithium salt can increase the number of free lithium ions, lower the glass transition temperature of the polymer matrix formed by monomer polymerization, thereby promoting polymer chain relaxation and thus improving the ionic conductivity of the polymer matrix, promoting lithium ion migration. By limiting the mass ratio of the lithium salt within the above range, smooth ion conduction can be ensured, ionic conductivity can be improved, thereby enhancing the charge-discharge performance of the battery, reducing the occurrence of side reactions, and improving the cycle life and safety of the battery.

[0069] As an example, the lithium salt includes at least one of lithium trifluoromethanesulfonate, lithium hexafluoroarsenate, lithium perchlorate, lithium difluorophosphate, lithium bis(fluorosulfonyl)imide, lithium bis(trifluoromethanesulfonyl)imide, lithium dioxalateborate, lithium difluorooxalateborate, lithium tetrafluoroborate, and lithium hexafluorophosphate.

[0070] According to some embodiments of the present invention, based on the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent, the mass percentage of the inorganic filler is 5%-50%. For example, it can be 5%, 10%, 20%, 30%, 40%, 50%, etc. The introduction of inorganic filler can reduce the crystallinity of the polymer matrix formed by monomer polymerization, increase amorphous regions, thereby improving the ion migration rate. Furthermore, inorganic filler has high thermal stability. By limiting the mass percentage of inorganic filler within the above range, the high-temperature thermal stability of the polymer matrix formed by monomer polymerization can be effectively improved. When the battery generates heat during operation or charging / discharging, inorganic filler can help disperse and conduct heat, reducing local overheating and thus reducing the risk of thermal runaway, improving battery safety and cycle performance. On the other hand, it can be uniformly dispersed in the polymer matrix, interacting with the polymer matrix and other components, improving interfacial contact performance, promoting ion and electron transport, and improving the electrochemical performance of the battery.

[0071] According to some embodiments of the present invention, the D50 particle size of the inorganic filler is 2nm-500nm. For example, it can be 2nm, 10nm, 50nm, 100nm, 200nm, 500nm, etc. By limiting the D50 particle size of the inorganic filler to the above range, the inorganic filler has better dispersibility and can be more uniformly dispersed in the polymer matrix. It can better interact with the polymer matrix and other components, improve interfacial properties, reduce interfacial impedance, improve interfacial smoothness, promote ion and electron transport, and improve the electrochemical performance of the battery. According to some specific embodiments of the present invention, the Dv50 of the inorganic filler is preferably 10nm-300nm.

[0072] It should be noted that the D50 particle size refers to the particle size corresponding to a cumulative volume distribution percentage of 50%, and is determined using a laser particle size analyzer (e.g., Malvern Master Size 3000) in accordance with the standard GB / T 19077-2016.

[0073] According to some embodiments of the present invention, the inorganic filler includes at least one of inorganic active filler and inorganic inert filler. The inorganic active filler can provide lithium ions as an active material. It disrupts the aggregated structure of the polymer matrix, reduces crystallinity, and increases the number of conductive polymer segments. Low activation energy active fillers contain many continuous defects, making ions prone to jumping. Furthermore, the active filler itself can provide a large number of lithium ions, thereby increasing the concentration of free lithium ions at the interface between the active filler and the polymer, enhancing ionic conductivity. In the event of thermal runaway in the battery cell, the inorganic active filler can delay heat propagation, increasing the time before cell failure occurs, thus providing the battery management system (BMS) with reaction time to take protective measures, which is beneficial to improving battery safety performance.

[0074] It is understood that, in the embodiments of this application, inorganic inert filler refers to a substance that does not contain lithium and does not undergo a chemical reaction in the battery, while inorganic active filler refers to a substance that contains lithium.

[0075] The inorganic active filler includes at least one of oxide active fillers, sulfide active fillers, halide active fillers, nitride active fillers, boride active fillers, and hydride active fillers; the oxide active filler includes at least one of garnet-type active fillers, perovskite-type active fillers, NASICON-type active fillers, and LISICON-type active fillers; the garnet-type active filler includes Li x1 La3Zr y1 A1 z1 O 12 and Li x2 La 3-y2 B y2 Zrz2 O 12 At least one of them, wherein Li x1 La3Zr y1 A1 z1 O 12 Satisfying: 6≤x1≤7, 1≤y1≤2, 0≤z1≤0.5, A1 includes at least one of Ta, Nb, Mg, Ti, Te, and W; Li x2 La 3-y2 B1 y2 Zr z2 O 12 Satisfying the following conditions: 6≤x²≤7, 0≤y²≤0.5, 1≤z²≤2, B1 includes at least one of Ca, Rb, Al, and Ga; the perovskite-type active filler includes Li. 3.3 La 0.53 TiO3, Li 3x3 La 2 / 3-x3 TiO3 and Li x4 Sr y3 M1 z3 At least one of TaO3, wherein Li 3x3 La 2 / 3-x3 TiO3 satisfies: 0 ≤ x3 ≤ 2 / 3; the NASICON-type active filler includes Li x5 Al y4 M2 z4 (PO4)3, Li x6 Y y5 Zr z5 At least one of (PO4)3, LiTi2(PO4)3, LiGe2(PO4)3, and LiGeTi(PO4)3, wherein Li x5 Al y4 M2 z4 (PO4)3 satisfies: 1.3 ≤ x5 ≤ 1.5, 0.3 ≤ y4 ≤ 0.5, 1.5 ≤ z4 ≤ 1.7, M2 includes at least one of Ti, Ge, Hf, Zn, Zr and Si, and Li x6 Y y5 Zr z5 (PO4)3 satisfies: 1.3 ≤ x6 ≤ 1.5, 0.3 ≤ y5 ≤ 0.5; the LISICON type active filler includes Li 3+x7 (P 1-x7 Si x7 O4, Li 3+x8 Ge x8 V 1-x8 At least one of O4, wherein Li 3+x7 (P 1-x7 Si x7 O4 satisfies: 1.5 ≤ x7 ≤ 1.7, Li3+x8 Ge x8 V 1-x8 O4 satisfies: 0.25 ≤ x8 ≤ 0.72; the sulfide active filler includes Argyrodite type LiPSM3X1 and Thio-LiSICON type Li 4-x9 A2 1-x9 B2 x9 S4 and at least one of glassy sulfides, wherein LiPSM3X1 satisfies: M3 includes at least one of O, Cu, Zn, Bi, Sn, Al, and In, X1 includes at least one of F, Cl, Br, and I, and Li 4-x9 A2 1-x9 B2 x9 S4 satisfies: 0 ≤ x9 ≤ 0.5; A2 includes at least one of Si, Sn, Ge, and Zr; B2 includes at least one of P, Al, Zn, and Ga; the glassy sulfide includes at least one of Li2S-P2S5, Li2S-SiS2, and Li2S-B2S3; the halide active filler includes LiX2, Li2M4X34, Li3M5X46, and Li x10 M6 y6 Ln z6 At least one of Cl3, wherein LiX2 satisfies: X2 includes at least one of F, Cl, Br and I; Li2M4X34 satisfies: M4 includes at least one of Mg, Mn, Fe, Zn and Cd; X3 includes at least one of F, Cl, Br and I; Li3M5X46 satisfies: M5 includes at least one of O, In, Y, Yb, Sc, Ho and Er; X4 includes at least one of F, Cl, Br and I; Li x10 M6 y6 Ln z6 Cl3 satisfies: 0≤x10≤0.5, 0≤y6≤0.83, 0≤z6≤0.83; M6 includes at least one of Ta, Zr, Ca, and Al; Ln includes at least one of La, Ce, Pr, Nd, and Sm; the nitride active filler includes at least one of LiPON, Li3N, Li7PN4, and LiSi2N3; the boride active filler includes Li2B4O7, Li2O-B2O3-P2O5, and Li 6+2x11 [B 10 S 18 ]S x11 At least one of them, wherein Li 6+2x11 [B 10 S 18 ]S x11The following conditions must be met: 0.8 ≤ x11 ≤ 1.2; the hydride active filler includes at least one of Li3AlH6, LiBH4, LiNH2, Li2NH, LiBH4-LiNH2, LiBHI, and LiBH4-LiX5, wherein LiBH4-LiX5 satisfies: X5 includes at least one of Cl, Br, and I; the inorganic inert filler includes oxide inert fillers, nitride inert fillers, boride inert fillers, halide inert fillers, dielectric ceramic inert fillers, and ferroelectric ceramic inert fillers. The inert packing material includes at least one of the following: piezoelectric ceramic inert packing material, diatomaceous earth inert packing material, mullite inert packing material, montmorillonite inert packing material, and kaolin inert packing material; the oxide inert packing material includes at least one of the following: silicon oxide, boron oxide, magnesium oxide, copper oxide, nickel oxide, calcium oxide, aluminum oxide, titanium oxide, zirconium oxide, vanadium oxide, lanthanum oxide, beryllium oxide, yttrium oxide, cerium oxide, and lead zirconium titanate; the nitride inert packing material includes at least one of the following: silicon nitride, titanium nitride, aluminum nitride, boron nitride, magnesium nitride, zirconium nitride, and silicon oxynitride.

[0076] It should be noted that NASICON-type active fillers refer to active materials with a sodium superionic conductor (NASICON) structure, which is a three-dimensional open framework structure composed of metal ions and polyhedra; LISICON-type active fillers refer to a class of materials with a lithium superionic conductor (LISICON) structure; Argyrodite type has a unique crystal structure, generally composed of chalcogen elements (such as sulfur, selenium, tellurium, etc.) and metal elements, and its structure contains an open framework structure.

[0077] According to some embodiments of the present invention, the initiator accounts for 0.1%-3% of the monomer mass. For example, it can be 0.1%, 0.5%, 1%, 2%, 3%, etc. By limiting the mass percentage of the initiator within the above range, problems such as free radical transfer to the solvent and bimolecular termination during free radical polymerization can be reduced, thereby improving the stability of the polymerization reaction, reducing side reactions such as oxidative decomposition, ensuring the quality and stability of the polymer, and achieving good synergistic effects with other components such as monomers, lithium salts, inorganic fillers, conductive agents, and crosslinking agents to jointly construct a stable polymer matrix structure. This helps optimize the performance of the polymer matrix, improve the overall performance of the electrode, and thus improve the cycle stability and safety performance of the battery.

[0078] According to some embodiments of the present invention, the D50 particle size of the conductive agent is 5nm-1000nm, for example, it can be 5nm, 10nm, 50nm, 100nm, 500nm, 1000nm, etc. By limiting the D50 particle size of the conductive agent to the above range, the conductive agent has both high conductivity and good dispersibility, and can be more uniformly distributed in the polymer matrix. Uniform distribution can ensure uniform current conduction in the electrode, avoid hot spots and dead lithium generation caused by excessive local current, and improve the cycle stability of the battery.

[0079] As an example, the conductive agent includes at least one of conductive graphite, conductive carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanotubes, graphene, silicon carbide, boron carbide, silicon boride, vanadium boride, magnesium boride, titanium boride, 6-amino-1-hexanol-polyacrylate ionic crosslinking polymer, hydroxyethyl ethylenediamine-polyacrylate ionic crosslinking polymer, diethylene glycolamine-polyacrylate ionic crosslinking polymer, 5-amino-1-pentanol-polyacrylate ionic crosslinking polymer, 4-amino-1-butanol-polyacrylate ionic crosslinking polymer, and N,N-bis(2-hydroxyethyl)ethylenediamine-polyacrylate ionic crosslinking polymer. The introduction of the conductive agent can improve the conductivity of the polymer matrix, construct an efficient electron transport network, reduce the internal resistance of the battery, and improve the charge and discharge efficiency of the battery.

[0080] As an example, the crosslinking agent includes isocyanate, propylenediamine, polyethylene glycol, polypropylene glycol, trimethylolpropane, trimethylolethane, polypropylene glycol glycidyl ether, zinc oxide, aluminum chloride, aluminum sulfate, sulfur, boric acid, borax, chromium nitrate, styrene, α-methylstyrene, acrylonitrile, acrylic acid, methacrylic acid, glyoxal, aziridine, ethyl orthosilicate, methyl orthosilicate, trimethoxysilane, p-toluenesulfonic acid, p-toluenesulfonyl chloride, dicumyl peroxide, bis(2,4-dichlorobenzoyl peroxide), aluminum isopropoxide, zinc acetate, titanium acetylacetonate, polycarbodiimide (preferably in combination with a conductive agent), acrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate, divinylbenzene, N-hydroxymethylacrylamide, and diacetone acrylamide. Preferably, the crosslinking agent is tetraethyl orthosilicate, methyl orthosilicate, trimethoxysilane, polycarbodiimide, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, tetraethylene glycol dimethacrylate, tetraethylene glycol diacrylate, 1,3-propanediol dimethacrylate, 1,2-propanediol dimethacrylate, or 1,3-propanediol dimethacrylate. The polymer comprises one or more of the following: alcohol esters, 1,2-propanediol diacrylate, 1,4-butanediol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4-butanediol diacrylate, 1,3-butanediol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate; more preferably, at least one of triethylene glycol dimethacrylate, triethylene glycol diacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate. The addition of a crosslinking agent forms chemical bonds that link the polymer chains, enhancing the mechanical properties, thermal stability, and electrochemical properties of the polymer matrix.

[0081] As an example, the solvent includes, but is not limited to, at least one of dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, propylene carbonate, N-methylpyrrolidone, fluoroethylene carbonate, acetonitrile, dimethyl sulfoxide, dimethylformamide, chloroform, ethyl acetate, N,N-dimethylformamide, N,N-dimethylacetamide, and tetrahydrofuran.

[0082] S2. The prepolymer precursor liquid is introduced into at least one side of the current collector for a second polymerization to form an interfacial flexible layer on at least one side of the current collector.

[0083] In this step, by introducing the prepolymer precursor liquid into at least one side of the current collector and then carrying out a second polymerization reaction, an interfacial flexible layer can be formed on at least one side of the current collector.

[0084] According to some embodiments of the present invention, the temperature of the second polymerization is 40°C-120°C. For example, it can be 40°C, 60°C, 80°C, 100°C, 120°C, etc. By limiting the temperature of the second polymerization within the above range, sufficient energy can be provided for the second polymerization to accelerate the polymerization reaction of the monomers, control the degree of the second polymerization, and achieve better bonding between the prepolymer precursor liquid and the active material, forming a stable active material layer and an interface flexible layer. This can reduce the structural collapse, particle breakage, and metal ion dissolution of the active material during the charge and discharge process, thereby improving the cycle life and safety of the battery.

[0085] According to some embodiments of the present invention, the second polymerization time is 10s-2min. For example, it can be 10s, 40s, 1min, 2min, etc. By limiting the second polymerization time within the above range, the degree of the second polymerization can be precisely controlled, which helps to form a uniform and stable active material layer and interface flexible layer, and can reduce the shedding and deformation of active material during charging and discharging, thereby improving the cycle life and safety of the battery.

[0086] The method of application is not specifically limited, and includes, but is not limited to, at least one of coating, spraying, and dipping. Those skilled in the art can choose flexibly as needed.

[0087] According to a specific embodiment of the present invention, the introduction method includes coating, and the coating includes gravure coating. Gravure coating can precisely control the coating thickness and uniformity, achieving a uniform coating effect, ensuring the consistent distribution of active material and prepolymer precursor liquid on the current collector, making the reaction of various parts of the battery more uniform during charging and discharging, reducing the risk of local overcharging, over-discharging or overheating, improving the consistency and reliability of the battery, reducing problems caused by local performance differences, and improving the safety performance and cycle stability of the battery.

[0088] It should be noted that gravure coating mainly consists of an unwinding device, a coating head, a drying device, and a rewinding device. The gravure coating process includes: placing the current collector to be coated on the unwinding device, adjusting the unwinding tension to keep the current collector flat; pouring the coating into the feed trough of the coating head, and starting the coating head. During the rotation of the gravure roller, the coating is transferred from the feed trough to the gravure roller's surface texture. A metering roller contacts the gravure roller to accurately measure the coating thickness. A doctor blade scrapes away excess coating from the surface of the gravure roller to ensure uniform coating thickness. As the current collector passes through the coating head, the coating on the gravure roller is transferred to the current collector, completing the coating process. The coated current collector enters the drying device, where hot air drying or infrared drying evaporates the solvent in the coating, allowing the coating to solidify on the current collector. The temperature and airflow of the drying device need to be adjusted according to the properties of the coating and drying requirements to ensure uniform drying and prevent problems such as blistering and cracking. After drying, the current collector enters the winding device, and the winding tension is adjusted to keep the current collector flat. The winding device collects the coated current collector, completing the entire coating process.

[0089] According to some embodiments of the present invention, the gravure coating speed is 0.5 m / min to 10 m / min. For example, it can be 0.5 m / min, 1 m / min, 3 m / min, 5 m / min, 10 m / min, etc. By limiting the gravure coating speed within the above range, gravure coating can better ensure the uniform distribution of active material and prepolymer precursor liquid on the current collector, making the reaction of various parts of the battery more uniform during charging and discharging, reducing the risk of local overcharging, over-discharging or overheating, improving the consistency and reliability of the battery, reducing problems caused by local performance differences, and improving the safety performance and cycle stability of the battery.

[0090] According to some embodiments of the present invention, the tension of the gravure coating is 30N-200N. For example, it can be 30N, 50N, 100N, 150N, 200N, etc. Appropriate tension can keep the current collector flat during the coating process, avoiding defects such as wrinkles and waves, and ensuring the uniformity and thickness accuracy of the coating. Appropriate tension can also increase the adhesion between the current collector and the coating. Tension ensures close contact between the current collector and the gravure roller, which helps the coating adhere better to the current collector, improving the reliability and cycle stability of the battery.

[0091] According to some embodiments of the present invention, the coating thickness of the gravure coating is 0.5 μm-3 μm. For example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, etc. By limiting the coating thickness of the gravure coating within the above range, the loading of active material can be ensured, while maintaining the stability of the electrode structure. This can balance the mechanical strength and ion transport performance of the electrode to a certain extent, and extend the cycle life of the battery.

[0092] Furthermore, when using gravure coating, the drying process enables secondary thermal polymerization, allowing the prepolymer precursor liquid and active material to undergo further polymerization, increasing the degree of polymerization, molecular weight, and cross-linking degree of the polymer. This allows the electrode to better withstand volume changes and stress during charge and discharge, reducing active material shedding and structural damage, thereby improving the battery's cycle life and performance stability. Secondary thermal polymerization also ensures more uniform coating curing, reducing surface unevenness and defects, improving electrode surface smoothness, filling pores, increasing the contact area and tightness between the electrode and electrolyte, reducing interfacial impedance, improving ion transport efficiency, reducing the risk of short circuits during battery assembly and use, and enhancing battery safety.

[0093] It should be noted that in the process of using gravure coating, the coating method can be continuous coating, intermittent coating or zebra coating, the coating size accuracy is ≤ ±0.3mm, the coating thickness accuracy is ±0.3um, and the oven temperature accuracy is ±2℃.

[0094] According to some embodiments of the present invention, before the step of mixing the monomer and initiator to perform the first polymerization to obtain the prepolymer precursor liquid, the method further includes: preparing an active material layer on at least one side of the current collector. Specifically, the active material is first prepared into an active slurry, and then introduced into at least one side of the current collector to form an active material layer. After that, the prepolymer precursor liquid is introduced into the side of the active material layer away from the current collector, so that the prepolymer precursor liquid can fill the interior of the active material layer. During the second polymerization reaction, the prepolymer precursor liquid can polymerize and solidify within the electrode, reducing defects and pores inside the electrode, preventing the occurrence of micro-short circuits, and preventing direct contact between the positive and negative electrodes, thereby preventing large-area short circuits and improving the safety performance and cycle stability of the battery.

[0095] It should be noted that the process of preparing an active substance into an active slurry usually involves mixing, stirring, and grinding the active substance with other components such as solvents and binders to obtain a homogeneous slurry system. This invention does not specifically limit the types of active substances, solvents, and binders; those skilled in the art can flexibly select them based on existing resources.

[0096] As an example, the adhesive includes, but is not limited to, at least one of polyvinyl alcohol (PVA), polytetrafluoroethylene (PTFE), polypropylene, polyethylene, polyvinylidene fluoride (PVDF), SBR rubber, fluorinated rubber, polyurethane, polyamide, sodium carboxymethyl cellulose (CMC), and polyacrylic acid.

[0097] As an example, the active material includes one of a positive electrode active material and a negative electrode active material, wherein the positive electrode active material includes, but is not limited to, at least one of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium vanadium phosphate, and lithium-rich manganese-based materials.

[0098] As an example, the negative electrode active material includes, but is not limited to, at least one of graphite, graphene, soft carbon, hard carbon, elemental silicon, silicon-oxygen materials, silicon-carbon materials, silicon-nitrogen composite materials, silicon-based alloys, elemental tin, tin oxides, tin-based alloys, lithium metal, lithium alloy negative electrodes, lithium titanium oxides, transition metal oxides, and transition metal sulfides.

[0099] According to some embodiments of the present invention, after mixing the monomer and initiator to perform a first polymerization to obtain a prepolymer precursor liquid, and before introducing the prepolymer precursor liquid to at least one side of the current collector for a second polymerization to form an interfacial flexible layer on one side of the current collector, the method further includes: mixing the prepolymer precursor liquid with an active material. Specifically, after mixing the prepolymer precursor liquid and the active material, the mixture is introduced onto the surface of the current collector for a second polymerization reaction. This one-step construction method, the combination of the prepolymer precursor liquid and the active slurry, and the secondary polymerization process, helps to form good conductive and lithium-conducting channels, improving the charge-discharge performance and efficiency of the battery. During the second polymerization process, volatile components such as solvents can be removed, allowing residual monomers to react further, reducing their negative impact on battery performance, effectively increasing the degree of polymerization, reducing water content (<100ppm), and preventing problems such as uneven areal density caused by excessively fast polymerization. Furthermore, the active material can be prepared as an active slurry, added to the prepolymer precursor liquid, mixed, and then introduced onto at least one side of the current collector for a second polymerization reaction.

[0100] As an example, the active material includes one of a positive electrode active material and a negative electrode active material.

[0101] As an example, the positive electrode active material includes at least one of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium vanadium phosphate, and lithium-rich manganese-based materials.

[0102] As an example, the negative electrode active material includes at least one of graphite, graphene, soft carbon, hard carbon, elemental silicon, silicon-oxygen materials, silicon-carbon materials, silicon-nitrogen composite materials, silicon-based alloys, elemental tin, tin oxides, tin-based alloys, lithium metal, lithium alloys, lithium titanium oxides, transition metal oxides, and transition metal sulfides.

[0103] According to some embodiments of the present invention, after the prepolymer precursor liquid is introduced into at least one side of the current collector, a second polymerization is performed to form an interfacial flexible layer on at least one side of the current collector. Following this step, a liquid injection operation is further included. Specifically, the electrode roll obtained by gravure coating is injected with liquid, and the injected electrode roll is placed in an oven for curing at a temperature of 50℃-80℃ for 3-12 hours. Curing evaporates the solvent in the electrode, forming a gel-like electrolyte. Finally, the cured electrode roll is dried at a temperature of 60℃-120℃ for 3-10 hours.

[0104] It should be noted that there are no specific limitations on the specific operation of the injection process, and those skilled in the art can make flexible choices as needed. Furthermore, the liquid used in the injection process includes electrolyte, and there are no specific limitations on the type of electrolyte; those skilled in the art can make flexible choices as needed.

[0105] According to some embodiments of the present invention, the method further includes preparing a solid electrolyte layer on the interface flexible layer. Specifically, after completing the preparation of the active material layer and the interface flexible layer, a solid electrolyte layer is added at specific locations to improve the overall structure of the solid-state battery. The presence of the solid electrolyte layer provides a dedicated channel for the transport of lithium ions in the battery. It has high ionic conductivity, which can promote the rapid migration of lithium ions between the positive and negative electrodes and improve the charge and discharge performance of the battery. Compared with traditional liquid electrolytes, solid electrolytes can reduce the risk of leakage and improve battery safety.

[0106] It should be noted that there are no special limitations on the raw material composition of the solid electrolyte layer. The use of conventional raw material compositions in the field is within the scope of the inventive concept of this application, and those skilled in the art can make flexible choices as needed.

[0107] According to the preparation method of this invention, the heterospatial polymerization technology enables controllable heterospatial polymerization of monomers through the first polymerization reaction, ensuring stable polymerization and improving product quality consistency. Ultrasonic polymerization is used in the thermal polymerization process to achieve high dispersion of monomers within the polymerization system, laying the foundation for constructing high-throughput ion transport channels and contributing to improved ion conduction performance of the battery, thereby enhancing charge and discharge efficiency. Furthermore, the molecular weight of the polymerization product can be controlled, achieving uniform solidification and ensuring the stability of battery performance.

[0108] Furthermore, by incorporating inorganic fillers combined with ultrasonic polymerization, the heterogeneous polymerization of each component material can be uniformly distributed, ensuring the consistency of the material at the microscopic level, avoiding local performance differences, thereby improving the overall performance stability, reducing interfacial impedance, which promotes ion and electron transport, and improving the battery's charge and discharge efficiency. Simultaneously, improving interfacial smoothness helps reduce defects and inhomogeneities at the interface, further reducing impedance and improving battery performance. The first polymerization reaction can improve the mechanical properties and electrochemical stability of the interfacial softening layer. Using ultrasonic polymerization allows for precise control of the monomer polymerization degree, improving ion transport channels and promoting Li... + Effective transport at the ceramic phase, ceramic-polymer interface, and intervention pathways improves ionic conductivity, thereby enhancing battery charge / discharge efficiency and power output. Furthermore, ultrasound promotes more uniform particle dispersion, preventing agglomeration and improving the mechanical strength and stability of the electrode. Simultaneously, uniformly dispersed particles also contribute to improved ion transport efficiency, further enhancing battery performance.

[0109] Furthermore, combining ultrasonic polymerization with the first polymerization process enables high dispersion of inorganic fillers and conductive agents. High dispersion ensures uniform distribution of inorganic fillers and conductive agents within the electrode, avoiding localized aggregation and inhomogeneity. This allows for the formation of continuous ion and electron transport pathways within the electrode. The polymer structure formed during the first polymerization provides ion transport channels, while the highly dispersed inorganic active fillers and conductive agents facilitate electron transport. The combination of these two factors achieves rapid ion / electron transport, improving battery performance. In the electrode composite process, combining ultrasonic polymerization with the first polymerization process allows for control over the degree of monomer polymerization on the electrode surface, thereby adjusting the physical and chemical properties of the electrode and improving battery cycle life and safety.

[0110] Furthermore, a prepolymer precursor solution is introduced into at least one side of the current collector using a gravure coating method to composite the electrode, thus preparing a separatorless battery. This simplifies the battery structure and reduces costs. Interface softening improves the problem of poor solid-solid contact, reduces interfacial impedance, and enhances the battery's cycle stability. After being introduced onto the electrode surface, the prepolymer precursor solution can penetrate into the electrode interior and solidify within it. The solidified prepolymer precursor solution can fill pores and defects in the electrode, reducing the risk of micro-short circuits. It also prevents large-area short circuits caused by direct contact between the positive and negative electrodes after thermal runaway, improving battery safety and cycle performance.

[0111] Furthermore, by employing electrode composite and interface softening technologies, all-solid-state battery electrodes can be constructed in one step, simplifying the manufacturing process and improving production efficiency. Compared to traditional multi-step preparation methods, this one-step construction method reduces potential errors and losses from intermediate steps, ensuring the quality and performance stability of the electrode. This one-step construction method enables the prepolymer precursor liquid to achieve highly dispersed and uniform distribution both inside and on the surface of the electrode. Inside the electrode, the uniform distribution of the prepolymer precursor liquid improves the structural stability and ion transport performance of the active material. On the surface, the uniformly distributed prepolymer precursor liquid improves contact with the solid electrolyte, reduces interfacial impedance, promotes ion transport, and establishes an ion / electron transport pathway. The ion transport pathway ensures rapid migration of lithium ions between the electrode and the solid electrolyte, improving the battery's charge / discharge efficiency and rate performance. The electron transport pathway ensures efficient electron transport within the electrode and in the external circuitry, reducing battery internal resistance and improving energy conversion efficiency. This technology is also applicable to conductive agents; that is, electrode composite and interface softening technologies enable highly dispersed and uniform distribution of conductive agents both inside and on the surface of the electrode, improving the utilization rate of the conductive agent and reducing battery internal resistance. Therefore, the electrode composite and interface softening technology enables the prepolymer precursor liquid, inorganic filler and conductive agent to be highly dispersed and uniformly distributed inside and on the surface of the electrode, thereby constructing an ion / electron transport pathway and effectively improving the electrochemical performance of the battery.

[0112] Furthermore, the electrode preparation technology of this invention, when applied to lithium batteries, improves the penetration into the microporous structure of the battery cell and the uniformity of the macroscopic distribution of polymers within the battery, solving the problems of uneven polymerization and wetting during the in-situ curing process. Batteries prepared by this method exhibit high ionic conductivity and electrochemical stability window, high mechanical strength, stable cycle performance, and excellent safety performance. Moreover, this method is low-cost, highly efficient, effectively controls product consistency, and achieves stable yield, facilitating large-scale production and development.

[0113] In a second aspect of the invention, an electrode 10 prepared by ex-situ polymerization is provided. According to an embodiment of the invention, the electrode comprises an electrode prepared by the method of the first aspect, with reference to... Figure 1 The electrode includes a current collector 1, an active material layer 2, and an interface flexible layer 3.

[0114] The primary function of current collector 1 is to carry the active material and collect the current generated by the electrochemical reaction, thereby converting chemical energy into electrical energy. The material of the current collector is not specifically limited; those skilled in the art can select it according to their needs.

[0115] According to an embodiment of the present invention, the active material layer 2 is disposed on at least one side of the current collector 1, and the interface flexible layer 3 is disposed on the side of the active material layer 2 away from the current collector 1.

[0116] According to the electrode of the above embodiments of the present invention, the active material layer is composed of a polymer matrix formed by monomer polymerization and the active material, and is disposed on one side of the current collector. The polymer matrix formed by monomer polymerization can fill the gaps in the active material, ensuring effective contact between the active material and the current collector, thereby improving electron transport efficiency. The interface flexible layer is composed of a polymer matrix formed by monomer polymerization and is located on the side of the active material layer away from the current collector. The interface softening of the interface flexible layer can improve the problem of poor solid-solid contact, reduce interface impedance, thereby improving ion transport efficiency. It can also alleviate the interface stress caused by volume changes during battery charging and discharging, enhance the stability of the electrode structure, and thus improve the cycle stability of the battery. In addition, since the active material releases oxygen when operating at high voltage, the release of oxygen can be suppressed through interface softening, thereby improving the thermal stability and safety of the battery. The polymer matrix, composed of monomers and initiators, facilitates the formation of a uniform polymer matrix within the active material layer and the interfacial flexible layer. Through ex-situ polymerization, high-flux ion transport channels are constructed during electrode composite formation, achieving high monomer dispersion and a uniform polymer matrix that is evenly distributed within the active material layer and the interfacial flexible layer. This enhances the stability of the electrode structure and significantly improves battery safety. The interfacial flexible layer, covering the active material layer, reduces the specific surface area of ​​the active material layer, resulting in a smoother SEI film formed during the first charge-discharge cycle, reducing side reactions and effectively improving the battery's initial coulombic efficiency. Therefore, the electrode provided in this application can improve the battery's cycle stability, initial coulombic efficiency, and safety performance.

[0117] According to some embodiments of the present invention, the electrode further includes a solid electrolyte layer 4, which is disposed on the side of the interface flexible layer 3 away from the active material layer 2. The solid electrolyte layer 4 can isolate the positive and negative electrodes, preventing direct contact between them and short circuits, thereby improving battery safety and reducing the risk of battery combustion, explosion, and other safety accidents, making the battery safer and more reliable during use. In addition, the solid electrolyte also provides support, ensuring the stability of the battery.

[0118] In a third aspect, the present invention provides a solid-state battery. According to embodiments of the invention, the solid-state battery comprises an electrode prepared by heterostomosis polymerization according to the first aspect or an electrode prepared by the method of the second aspect. This solid-state battery exhibits excellent safety performance, cycle performance, and initial coulombic efficiency.

[0119] In a fourth aspect, the present invention provides a separatorless battery. According to embodiments of the invention, the separatorless battery comprises an electrode prepared by heterostomosis polymerization according to the first aspect or an electrode prepared by the method of the second aspect. This separatorless battery exhibits excellent safety performance, cycle performance, and initial coulombic efficiency.

[0120] The present disclosure will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be construed as limiting the scope of the disclosure. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in the art or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0121] Example 1

[0122] 1. Preparation of electrode sheets:

[0123] 1) Dissolve the monomer, lithium salt, inorganic material, conductive agent, initiator, and crosslinking agent in a solvent and stir until homogeneous to form a solution. The monomer accounts for 15% of the total mass, the initiator accounts for 1% of the monomer mass, the lithium salt accounts for 15% of the total mass, and the inorganic filler accounts for 25% of the total mass. The monomer is ethylene glycol methacrylate, the lithium salt is lithium trifluoromethanesulfonate, and the inorganic filler is Li... 3.3 La 0.53 TiO3, conductive agent is conductive graphite, initiator is 2,2'-azobis(isobutyronitrile), crosslinking agent is isocyanate, solvent is dimethyl carbonate;

[0124] 2) Transfer the solution prepared in step 1) to an ultrasonic device and perform the first polymerization of the solution by heating and ultrasound to obtain a prepolymer precursor liquid. The heating and ultrasound temperature is 50℃, the ultrasonic polymerization frequency is 2MHz, the time is 6h, the degree of polymerization of the prepolymer precursor liquid is 30%, and the viscosity of the prepolymer precursor liquid is η=500Pa·s.

[0125] 3) The positive electrode active material NCM811, conductive carbon black, and binder polyvinylidene fluoride were dissolved in N-methylpyrrolidone in a mass ratio of 96:2:2. The solution was then coated onto the surface of the current collector, dried, and rolled for later use to obtain an electrode sheet. The prepolymer precursor solution prepared in step 2) was uniformly coated onto the electrode sheet using a gravure coating method. Before winding, the solvent on the surface of the electrode sheet was completely evaporated in an oven. The gravure coating parameters were as follows: speed 5 m / min, tension 100 N, coating thickness 1.5 μm, oven temperature (temperature of the second polymerization) 80 °C, drying time 1 min, coating method continuous, intermittent, or zebra coating, coating size accuracy ≤ ±0.3 mm, coating thickness accuracy ±0.3 μm, and oven temperature accuracy ±2 °C to obtain the positive electrode sheet prepared by heterospatial polymerization.

[0126] 2. Preparation of solid-state battery: The positive electrode obtained above is assembled with solid electrolyte and negative electrode to form a membrane-free battery. The negative electrode is prepared by mixing graphite, conductive carbon black, sodium carboxymethyl cellulose (CMC), and styrene-butadiene rubber (SBR) in a weight ratio of 93:2:3:2 with water to form a homogeneous slurry. The slurry is coated on a 10μm copper foil current collector. The areal density of the negative electrode is controlled so that the N:P ratio (capacity ratio of positive electrode material to negative electrode material per unit area) of the positive and negative electrodes is 1.1:1. The negative electrode is obtained by vacuum drying at 100℃, rolling and slitting.

[0127] A solid electrolyte is introduced onto the surface of a constructed positive electrode and / or negative electrode by coating or spraying. A solid electrolyte layer is formed by coating the positive active material layer of the positive electrode with a solid electrolyte solution on the side away from the positive current collector and drying it. A first electrode assembly including a stacked positive electrode and a solid electrolyte layer is obtained, with the thickness of the solid electrolyte layer being 10 μm.

[0128] Example 14

[0129] The difference between Example 14 and Example 1 is that the following steps are added to the electrode preparation process: After the electrode roll obtained in step 3) is injected with liquid, it is placed in an oven for curing at a temperature of 60°C for 6 hours, and then dried at a temperature of 90°C for 7 hours. The resulting electrode roll is then rolled and die-cut to obtain a positive electrode. The liquid injected is 1 mol of lithium hexafluorophosphate dissolved in a solvent with a mass ratio of EC:DEC:DMC = 1:1:1.

[0130] Example 15

[0131] The difference between Example 15 and Example 1 is that the thickness of the electrode obtained by ex-situ polymerization containing inorganic fillers is controlled within the range of 10-80 μm, so that a solid electrolyte layer is not required, and the interfacial flexible layer obtained by polymerization can serve as a solid electrolyte layer.

[0132] Example 16

[0133] The difference between Example 16 and Example 1 is that no inorganic materials were added to the prepolymer precursor liquid, while the rest is the same as in Example 1.

[0134] The electrodes of Examples 2-13 are the same as those of Example 1, except for the different experimental parameters (see Table 1).

[0135] Table 1 shows some of the experimental parameters of the electrode sheets in Examples 1-13 during the preparation process.

[0136] Table 1

[0137]

[0138]

[0139] Comparative Example 1

[0140] The difference between Comparative Example 1 and Example 1 is that the electrode obtained in Comparative Example 1 does not have an interface flexible layer and a polymer matrix formed by monomer polymerization, while the rest is consistent with Example 1.

[0141] Comparative Example 2

[0142] The difference between Comparative Example 2 and Example 1 is that the monomer, lithium salt, inorganic filler, conductive agent, initiator and crosslinking agent are dissolved in a solvent, stirred evenly to form a solution, and after complete polymerization, the solution is coated on at least one side of the current collector.

[0143] Comparative Example 3

[0144] The difference between Comparative Example 3 and Example 1 is that the monomer, lithium salt, inorganic filler, conductive agent, initiator and crosslinking agent are dissolved in a solvent, stirred evenly to form a solution, and the resulting solution is directly coated on at least one side of the current collector before polymerization.

[0145] Testing and Analysis

[0146] Under the same conditions, the batteries prepared in Examples 1-16 and Comparative Examples 1-3 were subjected to impedance, initial coulombic efficiency, cycle performance, and safety performance tests. The specific test methods are as follows:

[0147] Initial Coulombic Efficiency and Cycle Performance Tests: In an argon-filled glove box, positive and negative battery casings, stainless steel gaskets, spring sheets, positive electrode plates, and negative electrode plates were assembled into coin cells. The negative electrode plate was made of 150µm thick lithium metal, and the positive electrode plate was prepared as described above. After assembly, the coin cells were left to stand at 25°C for 6 hours. Then, a CT2001A charge / discharge tester was used for constant current charge / discharge mode testing. The battery was first charged with a charging cutoff voltage of 4.2V, followed by discharging with a discharge cutoff voltage of 2.75V. The test temperature was 25°C. The charge / discharge test first involved two cycles at a 0.1C rate for activation, followed by long cycles at a 0.5C rate. The initial charge / discharge capacity was recorded, the initial coulombic efficiency was calculated, and the capacity retention rate after 500 cycles was recorded.

[0148] Interfacial impedance: The coin cells prepared above (before cycling test) were tested using the AC impedance method in an electrochemical workstation. The voltage amplitude was set to 5mV and the frequency range was 0.1Hz to 1MHz.

[0149] Safety performance testing: The prepared positive electrode, solid electrolyte, and negative electrode were assembled into a 10Ah soft-pack battery. After electrolyte injection, the battery was immersed at 45℃ for 12 hours, followed by hot-pressing formation and a needle penetration test. Before the test, the battery was charged at a constant current and constant voltage rate of 0.33C to a cutoff voltage of 4.2V and then allowed to stand for 1 hour. The test was conducted in an explosion-proof chamber using a 3mm steel needle with a 45° cone angle at the tip (the needle surface was smooth, free of rust, oxide layer, and oil). The needle penetration speed was 0.1mm / s, penetrating the cell until it was completely pierced. After penetration, the battery was allowed to stand for 1 hour. If the battery did not catch fire or explode, it passed; otherwise, it failed.

[0150] The test results are shown in Table 2.

[0151] Table 2

[0152]

[0153]

[0154] " / " indicates no.

[0155] Combining Tables 1 and 2, it can be seen that compared with the batteries of Comparative Examples 1-3, the interfacial impedance of the batteries in Examples 1-15 is significantly reduced, and the initial coulombic efficiency and 500-cycle capacity retention are significantly improved. All batteries passed the needle penetration test when the inorganic filler ratio was ≥25% or the monomer polymerization was complete, effectively improving the safety performance of the cells.

[0156] Compared with Comparative Examples 2 and 3, Comparative Examples 2 and 3 did not use the method of heterogeneous polymerization to prepare the positive electrode sheet, which would lead to uneven polymerization of the polymer monomers, thereby affecting the wettability of the polymer inside the electrode sheet, failing to effectively fill the pores and defects in the electrode sheet, increasing the risk of micro-short circuits, and thus leading to a significant decrease in battery safety, as well as affecting the cycle performance of the battery.

[0157] Compared with Example 16, Examples 1-15 show that without the addition of inorganic fillers, thermal runaway cannot be suppressed, resulting in a significant decrease in battery safety and affecting the battery's cycle performance.

[0158] Compared with Example 1, when the polymer content is too low, the increase in the proportion of inorganic components leads to an increase in the specific surface area of ​​the particles on the electrode surface, which reduces the flatness of the SEI and consumes more lithium ions, resulting in a decrease in the initial coulombic efficiency. The increase in solid-solid interface contact resistance leads to a decrease in long-term cycling performance. When the polymer content is too high, the interface resistance, initial coulombic efficiency, and long-term cycling performance are basically the same, but the material cost increases significantly.

[0159] Compared with Example 1, Examples 4 and 5 show that when the proportion of inorganic filler is too low, it cannot effectively suppress the occurrence of thermal runaway, resulting in a significant decrease in battery safety. When the proportion of inorganic filler is too high, the performance of various components decreases significantly, similar to Example 2.

[0160] Compared with Example 1, Examples 6, 7, 8, and 9 show that when the monomer prepolymerization degree is low, the viscosity of the composite slurry is too low, and the inorganic filler in it cannot exist in a highly dispersed form, resulting in agglomeration. This prevents the filler from smoothly entering the electrode and distributing evenly, leading to obstruction of ion transport channels, the generation of dead lithium, and thus affecting the electrochemical performance and safety performance of the battery. When the monomer prepolymerization degree is too high, the molecular weight of the prepolymer is too high, which hinders its entry into the electrode. The ion and electron channels are not fully constructed and are unevenly distributed, thereby increasing the solid-solid contact resistance and affecting the coulombic efficiency and long-cycle performance.

[0161] Compared with Example 1, Examples 10 and 11 show that when the ultrasonic frequency is too low, the ultrasonic time is significantly increased to achieve the required degree of polymerization. However, the longer the time, the more monomers evaporate, resulting in a decrease in the polymer ratio of the final composite system and an increase in interfacial impedance, which in turn affects the cycle performance. When the ultrasonic frequency is too high, the required polymer can be achieved in a shorter time. However, the inorganic filler does not achieve a completely high dispersion effect at this time. When it is mixed with the positive electrode slurry, the inorganic filler agglomerates, affecting the ionic and electronic conductivity of the electrode and reducing the coulombic efficiency.

[0162] Compared with Example 1, Examples 12 and 13 show that the second polymerization temperature is too low, the monomer polymerization is incomplete, and a large number of free monomers are in the composite slurry. The poor thermal stability of the free monomers affects the overall thermal safety performance of the battery. The second polymerization temperature is too high, the product after monomer polymerization is too rigid, which is not conducive to lithium-ion transport. The solid-solid interface contact resistance increases significantly, and the first-cycle coulombic efficiency and long-cycle performance are affected.

[0163] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," "some implementations," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0164] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing electrode sheets by ex-situ polymerization, characterized in that, The method includes: The monomer and initiator are mixed and subjected to the first polymerization to obtain the prepolymer precursor liquid; The prepolymer precursor liquid is introduced into at least one side of the current collector for a second polymerization to form an interfacial flexible layer on at least one side of the current collector. The steps involve mixing monomers and initiators, performing a first polymerization to obtain a prepolymer precursor solution, including: mixing monomers, lithium salts, inorganic fillers, conductive agents, crosslinking agents, initiators, and solvents, and then performing a first polymerization to obtain a prepolymer precursor solution. The first polymerization method includes heated ultrasonic polymerization, which is a combination of thermal polymerization and ultrasonic polymerization; The temperature for the ultrasonic polymerization heating is 30℃-100℃; The frequency of the heated ultrasonic polymerization is 0.5MHz-5.0MHz; The heating and ultrasonic polymerization time is 1h-12h; The degree of polymerization of the prepolymer precursor liquid is 30%-60%; The viscosity of the prepolymer precursor liquid is η, and η satisfies: 500 < η ≤ 1000 Pa·s; Based on the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent, the inorganic filler accounts for 25%-50% of the total mass. The step of mixing the monomer and initiator to perform a first polymerization to obtain the prepolymer precursor liquid further includes: preparing an active material layer on at least one side of the current collector. The prepolymer precursor solution is introduced into the active material layer on the side away from the current collector.

2. The method according to claim 1, characterized in that, After mixing the monomer and initiator and performing a first polymerization to obtain a prepolymer precursor liquid, the step of introducing the prepolymer precursor liquid to at least one side of the current collector and performing a second polymerization to form an interfacial flexible layer on one side of the current collector further includes: mixing the prepolymer precursor liquid with an active material.

3. The method according to claim 2, characterized in that, The active material includes one of a positive electrode active material and a negative electrode active material; The positive electrode active material includes at least one of nickel-cobalt-manganese ternary materials, nickel-cobalt-aluminum ternary materials, lithium iron phosphate, lithium manganese iron phosphate, lithium cobalt oxide, lithium manganese oxide, lithium vanadium phosphate, and lithium-rich manganese-based materials. The negative electrode active material includes at least one of graphite, graphene, soft carbon, hard carbon, elemental silicon, silicon-oxygen materials, silicon-carbon materials, silicon-nitrogen composite materials, silicon-based alloys, elemental tin, tin oxides, tin-based alloys, lithium metal, lithium alloys, lithium titanium oxides, transition metal oxides, and transition metal sulfides.

4. The method according to claim 1, characterized in that, Based on the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent, the mass percentage of the monomer is 0.5%-30%.

5. The method according to claim 4, characterized in that, The monomers include at least one of acrylate monomers, acrylonitrile monomers, cycloolefin monomers, vinylene monomers, amide monomers, alkyl sulfides, sulfate monomers, borate ester monomers, cyanamide monomers, and quaternary ammonium salt monomers.

6. The method according to claim 4, characterized in that, Based on the total mass of the monomer, the initiator, the lithium salt, the inorganic filler, the conductive agent, and the crosslinking agent, the mass ratio of the lithium salt is 0.5%-30%.

7. The method according to claim 4, characterized in that, The initiator accounts for 0.1%-3% of the monomer's mass.

8. The method according to claim 1, characterized in that, The conductive agent has a D50 particle size of 5nm-1000nm.

9. The method according to claim 8, characterized in that, The conductive agent has a D50 particle size of 10nm-500nm.

10. The method according to claim 1, characterized in that, The D50 particle size of the inorganic filler is 2nm-500nm.

11. The method according to claim 10, characterized in that, The D50 particle size of the inorganic filler is 10nm-300nm.

12. The method according to claim 10, characterized in that, The inorganic filler includes at least one of inorganic active filler and inorganic inert filler; The inorganic active filler includes at least one of oxide active filler, sulfide active filler, halide active filler, nitride active filler, boride active filler and hydride active filler; The inorganic inert filler includes at least one of oxide inert fillers, nitride inert fillers, boride inert fillers, halide inert fillers, dielectric ceramic inert fillers, ferroelectric ceramic inert fillers, piezoelectric ceramic inert fillers, diatomaceous earth inert fillers, mullite inert fillers, montmorillonite inert fillers, and kaolin inert fillers.

13. The method according to any one of claims 1-3, characterized in that, The temperature for ultrasonic polymerization is 40℃-60℃.

14. The method according to any one of claims 1-3, characterized in that, The temperature for the second polymerization is 40℃-120℃; The second polymerization takes 10 seconds to 2 minutes.

15. The method according to any one of claims 1-3, characterized in that, The method of introduction includes at least one of coating, spraying, and dipping.

16. The method according to claim 15, characterized in that, The import method includes coating, and the coating includes gravure coating.

17. The method according to claim 16, characterized in that, The parameters of the gravure coating satisfy one of the following conditions: The gravure coating speed is 0.5 m / min-10 m / min; The tension of the gravure coating is 30N-200N; The coating thickness of the gravure coating is 0.5μm-3μm.

18. The method according to any one of claims 1-3, characterized in that, The method further includes: A solid electrolyte layer is prepared on the flexible interface layer.

19. An electrode sheet prepared by ex-situ polymerization, characterized in that, This includes electrodes prepared using the method described in any one of claims 1-18.

20. A separatorless battery, characterized in that, The membraneless battery includes an electrode prepared by any one of the methods described in claims 1-18 or the electrode described in claim 19.

21. A solid-state battery, characterized in that, The solid-state battery includes an electrode prepared by any one of claims 1-18 or the electrode described in claim 19.

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