Secondary battery, manufacturing method thereof, battery device, energy storage device, and power utilization device

Abstract

The invention provides a secondary battery and a manufacturing method thereof, a battery device, an energy storage device and a power utilization device, which are at least beneficial to improving the performance of the secondary battery. The manufacturing method comprises the steps that magnetic composite filler comprising an ionic conductor core is prepared, the surface of the ionic conductor core is sequentially coated with a magnetic functional layer and a protective layer, the magnetic functional layer is made of a magnetic material, and the protective layer is made of an oxide; preparing a polymerization precursor comprising the magnetic composite filler, a polymer matrix, an initiator, a lithium salt and a solvent; coating the polymeric precursor under a pulsed magnetic field to form a film, so that the magnetic composite filler is directionally arranged along the thickness direction of a film layer; initiating the polymerization precursor to generate polymerization reaction, so that the polymerization precursor is cured and molded into a solid electrolyte membrane; a positive plate and a negative plate are provided, the positive plate, the solid electrolyte membrane and the negative plate are subjected to winding treatment or lamination treatment and then put into the shell, and an initial battery cell is formed.

Description

Technical Field

[0001] This application relates to the field of battery technology, and in particular to a secondary battery and its manufacturing method, battery device, energy storage device and power consumption device. Background Technology

[0002] Composite solid-state electrolytes, as a technological approach combining the high ionic conductivity of inorganic solid-state electrolytes with the good processing performance of polymer electrolytes, have received widespread attention in the field of solid-state batteries in recent years. An ideal composite solid-state electrolyte should be able to fully leverage the fast ion conduction advantage of inorganic components and the interfacial adaptability of organic components to achieve a synergistic effect of 1+1>2.

[0003] However, constructing an effective ion conduction network in a composite system remains a core challenge in this field. Traditional methods for preparing composite solid electrolytes mainly rely on mechanical mixing or solution blending, resulting in a largely random distribution of inorganic fillers in the polymer matrix. This disordered structure leads to discontinuous and tortuous ion conduction pathways, severely limiting the overall performance of the composite electrolyte. Summary of the Invention

[0004] This application provides a secondary battery and its manufacturing method, battery device, energy storage device, and power consumption device, which at least helps to improve the performance of the secondary battery.

[0005] According to some embodiments of this application, one aspect of this application provides a method for manufacturing a secondary battery, comprising: preparing a solid electrolyte membrane, the preparation steps including: preparing a magnetic composite filler, the magnetic composite filler including an ion conductor core, the surface of the ion conductor core being sequentially coated with a magnetic functional layer and a protective layer, the material of the magnetic functional layer including a magnetic material, and the material of the protective layer including an oxide; preparing a polymerization precursor, the polymerization precursor including the magnetic composite filler, a polymer matrix, an initiator, a lithium salt, and a solvent; coating the polymerization precursor into a film under a pulsed magnetic field, so that the magnetic composite filler is oriented along the film thickness direction; initiating a polymerization reaction of the polymerization precursor, so that the polymerization precursor is solidified into a solid electrolyte membrane; providing a positive electrode sheet and a negative electrode sheet, and placing the positive electrode sheet, the solid electrolyte membrane, and the negative electrode sheet into a casing after winding or stacking to form an initial battery cell, the solid electrolyte membrane being located between the positive electrode sheet and the negative electrode sheet.

[0006] In some embodiments, the magnetic field strength of the pulsed magnetic field is 0.2T~0.5T, the frequency is 0.1Hz~10Hz, the duty cycle is 40%~60%, and the duration is 30s~10min.

[0007] In some embodiments, the magnetic functional layer is formed using a chemical coprecipitation method, and the preparation steps include: dispersing the ionic conductor core in a substrate containing Fe... 2+ and Fe 3+In an aqueous solution, under the protection of an inert gas, an alkaline precipitant is added to adjust the pH to 8-12; the reaction is carried out at 20℃-100℃ for 0.5-12 hours; after the reaction is completed, the mixture is annealed at 200℃-600℃ for 0.5-6 hours.

[0008] In some embodiments, the protective layer is formed using a sol-gel method, and the preparation steps include: dispersing an ionic conductor core with a magnetic functional layer in an alcohol solvent; adding a silicon source precursor; and performing a hydrolysis-condensation reaction using an alkaline or acidic catalyst at 20°C to 80°C for 1 to 24 hours.

[0009] In some embodiments, the viscosity of the polymer precursor at 25°C is 100 mPa·s to 50000 mPa·s, and the solid content is 20 wt% to 80 wt%.

[0010] In some embodiments, the number-average molecular weight of the polymer matrix ranges from 1000 g / mol to 100000 g / mol.

[0011] In some embodiments, the polymer matrix is ​​selected from polyether polymers, polyester polymers, polycarbonate polymers, polynitrile polymers, polysiloxane polymers, polyphosphononitrile polymers, or copolymers thereof.

[0012] In some embodiments, the polymer matrix includes ether oxygen units, and the molar ratio of lithium ions in the lithium salt to ether oxygen units in the polymer matrix is ​​0.01:1 to 0.2:1.

[0013] In some embodiments, the amount of initiator in the polymerization precursor is 0.05 wt% to 10 wt% of the polymer matrix mass.

[0014] In some embodiments, the polymerization precursor further includes a crosslinking agent, the amount of which is 0.1 wt% to 20 wt% of the polymer matrix mass.

[0015] According to some embodiments of this application, another aspect of this application provides a secondary battery, including: a casing, the casing including a positive electrode, a solid electrolyte, and a bare cell formed by winding or stacking a negative electrode; wherein, the solid electrolyte includes a magnetic composite filler, a lithium salt, and an electrolyte matrix, the magnetic composite filler being oriented in the electrolyte matrix along the direction from the positive electrode to the negative electrode, the magnetic composite filler including an ion conductor core, the surface of the ion conductor core being sequentially coated with a magnetic functional layer and a protective layer, the material of the magnetic functional layer including a magnetic material, and the material of the protective layer including an oxide; the lithium salt is dispersed in the electrolyte matrix; the electrolyte matrix is ​​formed by the polymerization reaction of a polymer matrix and an initiator.

[0016] In some embodiments, the particle size of the ion conductor core is 200 nm to 1000 nm; the thickness of the magnetic functional layer is 10 nm to 200 nm; and the thickness of the protective layer is 1 nm to 50 nm.

[0017] In some embodiments, the total particle size range of the magnetic composite filler is 300 nm to 1500 nm.

[0018] In some embodiments, the porosity of the protective layer is 5% to 50%.

[0019] In some embodiments, the mass of the magnetic functional layer accounts for 3wt% to 40wt% of the mass of the magnetic composite filler.

[0020] In some embodiments, the saturation magnetization of the magnetic composite filler is 5 Am. 2 / kg~50Am 2 / kg.

[0021] According to some embodiments of this application, another aspect of this application provides a battery device, including a secondary battery prepared by the manufacturing method of the secondary battery in the above embodiments, or the secondary battery in the above embodiments. The battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

[0022] According to some embodiments of this application, another aspect of this application provides an energy storage device, including the battery device in the above embodiments, the battery device being used to store electrical energy.

[0023] According to some embodiments of this application, this application also provides an electrical device, including the battery device in the above embodiments, the battery device being used to provide electrical energy.

[0024] The technical solution provided in this application has at least the following advantages: In the secondary battery manufacturing method provided in this application embodiment, a magnetic composite filler including an ion-conducting core is prepared. The surface of the ion-conducting core is sequentially coated with a magnetic functional layer and a protective layer. The ion-conducting core provides a rapid ion transport channel. The magnetic functional layer, coated on the surface of the ion-conducting core, endows the magnetic composite filler with magnetic field responsiveness. The protective layer, covering the outside of the magnetic functional layer, plays a triple role of electrochemical isolation, interface optimization, and dispersion stabilization. In the polymerization precursor, the polymer matrix serves as the continuous phase of the solid electrolyte membrane, providing not only mechanical support but also participating in ion conduction. The lithium salt serves as the source of lithium ions, and the initiator is used to initiate the polymerization reaction to solidify the polymerization precursor into a solid electrolyte membrane. The polymer precursor is coated into a film under a pulsed magnetic field. The magnetic composite filler is oriented along the thickness direction of the film by inducing the magnetic field. The essential difference from conventional electrospinning and freeze-drying orientation technology is that it adopts non-contact magnetic field induction, which avoids the damage of physical stress to the magnetic composite filler. At the same time, the "drive-relaxation" cycle mechanism of the pulsed magnetic field can effectively prevent excessive particle agglomeration and promote the formation of an ordered chain structure. It has good process controllability and scalability potential. Compared with the "one-step" of constant magnetic field, the "gradual optimization" strategy of pulsed magnetic field can form through ion channels with fewer defects and better continuity.

[0025] Through a three-layer core-shell structure and a synergistic design induced by a pulsed magnetic field, key problems faced by traditional composite solid electrolytes, such as tortuous ion conduction paths, high interfacial impedance, and difficult processing, have been systematically solved, providing a new technological path for the development of high-performance solid-state secondary batteries. Solid-state secondary batteries are expected to achieve comprehensive improvements in energy density, cycle life, and safety performance, enabling high-capacity applications suitable for long-term energy storage, such as energy storage systems that can operate continuously for 4 to 8 hours at rated power. This provides crucial technological support for the development of next-generation high-performance electrochemical energy storage systems. Attached Figure Description

[0026] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart corresponding to a method for manufacturing a secondary battery provided in an embodiment of this application. Detailed Implementation

[0028] As can be seen from the background technology, traditional methods for preparing composite solid electrolytes mainly rely on mechanical mixing or solution blending. The distribution of inorganic fillers in the polymer matrix is ​​basically random. This disordered structure leads to discontinuous and tortuous ion conduction paths, which severely limits the overall performance of the composite electrolyte.

[0029] The preparation of ceramic-polymer composite solid electrolytes typically employs either physical blending or solution casting. Physical blending involves mechanically mixing ceramic powder and polymer in a molten state, dispersing the filler within the matrix through shear force, and then preparing the composite membrane through hot pressing or extrusion molding. Solution casting involves dissolving or dispersing ceramic powder and polymer separately in appropriate solvents, mixing them uniformly, and then forming the composite membrane through solvent evaporation or chemical cross-linking.

[0030] In the composite electrolytes prepared by these two methods, the ceramic fillers are basically randomly distributed, with a lack of effective connections between the filler particles. Ion conduction mainly relies on the polymer matrix and a small amount of ceramic-polymer interface region. In this structure, ion transport requires frequent hopping between different phases, resulting in discontinuous conduction paths and high impedance. To improve ionic conductivity, a large amount of ceramic filler (>30 wt%) is usually added, but high filler content leads to decreased mechanical properties and processing difficulties in the composite material.

[0031] To address this issue, researchers have proposed various techniques for controlling filler arrangement, including stretching orientation, electric field induction, and template methods. However, these methods still have limitations in terms of control precision, preparation efficiency, and cost. Stretching orientation easily leads to filler particle breakage, while electric field induction requires the filler to possess electrical response characteristics, and the electric field strength is difficult to control precisely. Although template methods can achieve a certain degree of ordered structure, the process is complex and difficult to scale up.

[0032] The ceramic-polymer composite solid electrolyte technology faces several key problems and technical bottlenecks in practical applications.

[0033] First, the random distribution of inorganic fillers is the fundamental problem restricting the improvement of composite electrolyte performance. Randomly distributed ceramic particles cannot form continuous fast ion conduction channels. Ion transport needs to jump frequently between different phase interfaces, resulting in a limited improvement in overall ionic conductivity, which is usually only 2 to 3 times that of pure polymer electrolytes, far from the theoretical expectation.

[0034] Secondly, conventional preparation methods make it difficult to precisely control the dispersion state and orientation of fillers, which can easily lead to filler agglomeration. Agglomerated areas not only fail to perform fast ion conduction but also become stress concentration points, reducing the mechanical properties and reliability of composite materials.

[0035] Third, while high filler content helps improve ionic conductivity, it significantly deteriorates the processing performance of composite electrolytes. The membrane material is prone to defects such as cracks and holes, and its poor flexibility makes it difficult to meet battery assembly requirements.

[0036] Fourth, each orientation control technology has its own limitations: stretching orientation can easily lead to the breakage of filler particles and the orientation of matrix molecular chains, affecting ion conduction; electric field induction requires special electrically responsive fillers, and uneven electric field distribution can lead to inconsistent orientation effects; template method is complex, costly, and difficult to remove templates.

[0037] Finally, there is a lack of efficient preparation technologies suitable for continuous production, and most existing methods remain at the laboratory stage, making it difficult to meet the requirements of industrial production.

[0038] This application provides a secondary battery and its manufacturing method, battery device, energy storage device, and power consumption device. In the manufacturing method, through structural design and process control, a through-type fast ion conduction channel is constructed in the polymer matrix, which can significantly improve the ionic conductivity and interface stability of the composite solid electrolyte, providing technical support for the next generation of high-performance solid-state secondary batteries.

[0039] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0040] In the description of the embodiments of this application, when a component "includes" another component, other components are not excluded unless otherwise stated, and other components may be further included.

[0041] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments, the term "component" is also intended to include the plural form unless the context clearly indicates otherwise.

[0042] The embodiments of this application will now be described in detail with reference to the accompanying drawings. However, those skilled in the art will understand that many technical details have been provided in the embodiments of this application to facilitate a better understanding of the application. However, the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0043] Figure 1This is a flowchart corresponding to a method for manufacturing a secondary battery provided in an embodiment of this application.

[0044] refer to Figure 1 The method for manufacturing a secondary battery provided in this application includes: S11. Preparation of a solid electrolyte membrane, the preparation steps include: S101. Prepare a magnetic composite filler, the magnetic composite filler includes an ion conductor core, the surface of the ion conductor core is sequentially coated with a magnetic functional layer and a protective layer, the material of the magnetic functional layer includes a magnetic material, and the material of the protective layer includes an oxide. S102. Prepare a polymerization precursor, which includes a magnetic composite filler, a polymer matrix, an initiator, a lithium salt, and a solvent. S103. The polymerization precursor is coated into a film under a pulsed magnetic field so that the magnetic composite filler is oriented along the film thickness direction. S104. Initiate a polymerization reaction in the polymerization precursor to solidify the polymerization precursor into a solid electrolyte membrane. S12. Provide positive and negative electrode sheets. After the positive electrode sheet, solid electrolyte membrane and negative electrode sheet are wound or stacked, they are placed into the housing to form an initial battery cell. The solid electrolyte membrane is located between the positive and negative electrode sheets.

[0045] In the secondary battery manufacturing method provided in this application embodiment, a magnetic composite filler including an ion-conducting core is prepared. The surface of the ion-conducting core is sequentially coated with a magnetic functional layer and a protective layer. The ion-conducting core provides a rapid ion transport channel. The magnetic functional layer, coated on the surface of the ion-conducting core, endows the magnetic composite filler with magnetic field responsiveness. The protective layer, covering the outside of the magnetic functional layer, plays a triple role of electrochemical isolation, interface optimization, and dispersion stabilization. In the polymerization precursor, the polymer matrix serves as the continuous phase of the solid electrolyte membrane, providing not only mechanical support but also participating in ion conduction. The lithium salt serves as the source of lithium ions, and the initiator is used to initiate the polymerization reaction to solidify the polymerization precursor into a solid electrolyte membrane. The polymer precursor is coated into a film under a pulsed magnetic field. The magnetic composite filler is oriented along the thickness direction of the film by inducing the magnetic field. The essential difference from conventional electrospinning and freeze-drying orientation technology is that it adopts non-contact magnetic field induction, which avoids the damage of physical stress to the magnetic composite filler. At the same time, the "drive-relaxation" cycle mechanism of the pulsed magnetic field can effectively prevent excessive particle agglomeration and promote the formation of an ordered chain structure. It has good process controllability and scalability potential. Compared with the "one-step" of constant magnetic field, the "gradual optimization" strategy of pulsed magnetic field can form through ion channels with fewer defects and better continuity.

[0046] Through a three-layer core-shell structure and a synergistic design induced by a pulsed magnetic field, key problems faced by traditional composite solid electrolytes, such as tortuous ion conduction paths, high interfacial impedance, and difficult processing, have been systematically solved, providing a new technological path for the development of high-performance solid-state secondary batteries. Solid-state secondary batteries are expected to achieve comprehensive improvements in energy density, cycle life, and safety performance, enabling high-capacity applications suitable for long-term energy storage, such as energy storage systems that can operate continuously for 4 to 8 hours at rated power. This provides crucial technological support for the development of next-generation high-performance electrochemical energy storage systems.

[0047] In S101, the ionic conductor core can be Li 1+x Al x Ti 2-x (PO4)3(LATP), where x is 0.1~0.5, for example, Li 1.1 Al 0.1 Ti 1.9 (PO4)3, Li 1.2 Al 0.2 Ti 1.8 (PO4)3, Li 1.3 Al 0.3 Ti 0.7 (PO4)3, Li 1.4 Al 0.4 Ti 1.6 (PO4)3 or Li 1.5 Al 0.5 Ti 1.5 (PO4)3. LATP, as a fast ion conductor with a NASICON (sodium superionic conductor) structure, has high ionic conductivity (>10). -4 With its good S / cm ratio and excellent chemical stability, it is an ideal inorganic component for composite solid electrolytes.

[0048] The ionic conductor nucleus can also be selected from Li 1+x Al x Ge 2-x (PO4)3, Li 1+x Y x Zr 2-x (PO4)3, Li 1+x Al x Sn 2-x (PO4)3, Li 1+x Al x Hf 2-x (PO4)3 and other NASICON structural derivatives, or selected from garnet-type, perovskite-type, sulfide-type, halide-type solid electrolytes, and any combination thereof.

[0049] The particle size of the ionic conductor nucleus is 200nm~1000nm, for example 200nm~300nm, 300nm~400nm, 400nm~450nm, 450nm~550nm, 550nm~600nm, 600nm~800nm, 800nm~1000nm.

[0050] The uniformity of the particle size of the ionic conductor nucleus is characterized by the ratio of D90 to D10, where the ratio of D90 to D10 is greater than 1 and less than 3, and can be greater than 1 and less than 1.5. This narrow distribution is conducive to the formation of a uniform oriented arrangement structure.

[0051] D90 refers to the particle size at which the cumulative percentage of particles reaches 90% in a particle size distribution.

[0052] D10 means that 10% of the particles in the particle size distribution are smaller than this value.

[0053] In some embodiments, ionic conductor nuclei can be prepared by methods such as solid-state methods, sol-gel methods, co-precipitation methods, hydrothermal or solvothermal methods, spray pyrolysis methods, and mechanical ball milling methods.

[0054] Taking LATP as an example, the preparation steps of the ionic conductor core include: mixing lithium sources such as Li2CO3, LiOH or LiNO3, aluminum sources such as Al2O3, Al(NO3)3 or Al(OH)3, titanium sources such as TiO2 or Ti(OC4H9)4, and phosphorus sources such as NH4H2PO4 or (NH4)2HPO4 according to stoichiometric ratio; calcining at 800℃~900℃ for 2h~24h; and then obtaining powder of the target particle size by ball milling and sieving.

[0055] The material of the magnetic functional layer can be selected from ferrite, metal oxide, metal alloy or magnetic composite material. Ferrite magnetic materials can be selected, including Fe3O4, γ-Fe2O3, MFe2O4 (where M is a transition metal such as Co, Ni, Mn, Zn, Cu, etc.), barium ferrite, strontium ferrite, etc.

[0056] In some embodiments, the method for forming a magnetic functional layer on the surface of an ionic conductor core is chemical coprecipitation, because it can achieve uniform and controllable coating.

[0057] For example, the preparation steps include: dispersing the ionic conductor core in a substrate containing Fe. 2+ and Fe 3+ In an aqueous solution, under the protection of an inert gas, an alkaline precipitant is added to adjust the pH value to 8-12; the reaction is carried out at 20℃-100℃ for 0.5h-12h; after the reaction is completed, the mixture is annealed at 200℃-600℃ for 0.5h-6h to improve the crystallinity of the magnetic functional layer.

[0058] In Fe 2+ and Fe 3+ In aqueous solution, Fe 2+ with Fe 3+ The molar ratio can be in the range of 0.3 to 0.7, for example, it can be 0.3, 0.4, 0.5, 0.6 or 0.7.

[0059] Alkaline precipitants can be selected from NH3·H2O, NaOH, or KOH.

[0060] In other embodiments, the method for forming a magnetic functional layer on the surface of an ionic conductor core may also employ a sol-gel method, a hydrothermal method, an atomic layer deposition method, a chemical vapor deposition method, or a physical vapor deposition method.

[0061] The magnetic functional layer can also be designed with a multilayer structure, such as Fe3O4 / Fe2O3, Co / CoO, Ni / NiO, etc., or use doped and modified magnetic materials to adjust the magnetic response characteristics.

[0062] The thickness of the magnetic functional layer ranges from 10nm to 200nm, specifically 10nm, 20nm, 30nm, 40nm, 60nm, 70nm, 100nm, 150nm, or 200nm.

[0063] The mass of the magnetic functional layer accounts for 3wt% to 40wt% of the total mass of the magnetic composite filler, for example, 3wt%, 5wt%, 10wt%, 20wt%, 25wt%, 30wt%, 35wt%, or 40wt%.

[0064] By controlling the thickness and composition of the magnetic functional layer, the saturation magnetization of the magnetic composite filler can be made to 5 Am. 2 / kg~50Am 2 / kg, for example, it could be 5Am 2 / kg, 10Am 2 / kg, 15Am 2 / kg, 20Am 2 / kg, 25Am 2 / kg, 30Am 2 / kg, 35Am 2 / kg, 40Am 2 / kg, 45Am 2 / kg or 50Am 2 / kg. This saturation magnetization range ensures effective orientation under a suitable magnetic field while avoiding irreversible aggregation caused by excessive magnetic interactions.

[0065] The protective layer is selected from inorganic oxides, inorganic nitrides, inorganic carbides, organic-inorganic hybrid materials, or polymer coatings. It can be selected from inorganic oxides, including single oxides such as SiO2, Al2O3, TiO2, ZrO2, HfO2, Ta2O5, Nb2O5, CeO2, Y2O3, MgO, CaO, BaO, B2O3, and P2O5, or composite oxides such as SiO2-Al2O3, SiO2-TiO2, and Al2O3-ZrO2.

[0066] In some embodiments, the protective layer is formed by a sol-gel method. Taking SiO2 as an example, the preparation steps include: dispersing the ionic conductor core with a magnetic functional layer in an alcohol solvent; adding a silicon source precursor; and performing a hydrolysis-condensation reaction using an alkaline or acidic catalyst at 20°C to 80°C for 1 to 24 hours.

[0067] The alcohol solvent is selected from ethanol or isopropanol.

[0068] The silicon source precursor is selected from tetraethyl orthosilicate, methyl orthosilicate, methyltriethoxysilane or vinyltriethoxysilane.

[0069] In other embodiments, the protective layer may be formed by atomic layer deposition, chemical vapor deposition, or layer-by-layer self-assembly.

[0070] The protective layer can also be surface functionalized, such as by introducing functional groups such as amino, thiol, epoxy, and vinyl groups, to enhance the interfacial bonding with the polymer matrix.

[0071] The thickness of the protective layer can be controlled by the amount of precursor used. The thickness of the protective layer is 1nm~50nm, for example, it can be 1nm, 3nm, 5nm, 10nm, 15nm, 20nm, 30nm, 40nm or 50nm.

[0072] The porosity of the protective layer is 5% to 50%, specifically 5%, 10%, 15%, 25%, 30%, 40%, or 50%. This controllable pore structure provides effective physical protection while ensuring low-impedance lithium-ion transport.

[0073] After the above multi-layer coating, the total particle size range of the magnetic composite filler is 300nm~1500nm, such as 300nm~400nm, 400nm~500nm, 500nm~600nm, 600nm~700nm, 700nm~1000nm or 1000nm~1500nm.

[0074] In a specific example, the batch preparation of magnetic composite fillers can adopt a continuous process route: the ionic conductor core is prepared by spray pyrolysis-continuous calcination, and the raw material solution is continuously calcined in a tube furnace after ultrasonic atomization. The temperature gradient is set as follows: 400℃~600℃ in the preheating zone, 800℃~900℃ in the reaction zone, and gradually reduced to room temperature in the cooling zone. The residence time is controlled at 2h~4h by the conveying speed. The calcined particles are then subjected to airflow classification to obtain narrowly distributed powder with a D50 of 450nm~550nm, where D50 represents the particle size corresponding to a cumulative particle size distribution percentage of 50%. The magnetic functional layer is prepared using a continuous co-precipitation reactor. The ionic conductor core is dispersed in deionized water at a concentration of 10wt%~20wt%, and a mixed solution of FeSO4·7H2O and FeCl3·6H2O (Fe 2+ / Fe 3+ The molar ratio of TEOS to ammonia is 1:2. Nitrogen gas is purged into the reactor for protection. The pH is controlled at 10.0±0.2 using an automatic titration system. The reaction temperature is 65±2℃, and the residence time is 45-60 min. The ionic conductor cores coated with the magnetic functional layer are magnetically separated, washed, and dried before proceeding to the next step. The protective layer employs fluidized bed coating technology. The ionic conductor cores coated with the magnetic functional layer are suspended in the fluidized bed reactor. TEOS vapor and ammonia vapor are simultaneously introduced, causing a hydrolysis-condensation reaction on the particle surface. The thickness of the protective layer is precisely controlled by adjusting the TEOS feed rate (0.5 mL / min / kg~2.0 mL / min / kg) and reaction time (30-60 min). After coating, the protective layer is annealed at 450℃ for 30 min to improve its density.

[0075] In S102, the solvent plays a dispersing role in the preparation of the polymerization precursor. After subsequent curing and molding, the solvent needs to be removed. Therefore, the mass of the solid electrolyte membrane is equal to the total mass of the other components in the polymerization precursor except for the solvent.

[0076] The mass fraction of magnetic composite filler in solid electrolyte membranes ranges from 5wt% to 70wt%, for example, 5wt%, 10wt%, 20wt%, 25wt%, 30wt%, 40wt%, 50wt%, 60wt%, or 70wt%. This content range balances the improvement of ionic conductivity with processing performance.

[0077] The polymer matrix can be selected from polyether polymers, polyester polymers, polycarbonate polymers, polynitrile polymers, polysiloxane polymers, polyphosphononitrile polymers, or copolymers thereof such as block copolymers, graft copolymers, and crosslinked polymers. It can be selected from polyether polymers or their block copolymers, including polyethylene oxide, polypropylene oxide, polytetrahydrofuran, polyoxymethylene, and various block combinations thereof, such as PEO-PPO diblock, PEO-PPO-PEO triblock, PPO-PEO-PPO triblock, PEO-PTMO-PEO triblock copolymers, and star-shaped or comb-shaped PEO-based polymers. Taking PEO-PPO-PEO triblock copolymer as an example, the mass ratio of PEO to PPO ranges from 50:50 to 90:10, such as 50:50, 60:40, 65:35, 68:32, 72:28, 75:25, 80:20 or 90:10. This ratio balances ionic conductivity and mechanical properties.

[0078] Conventional composite solid electrolytes often use a single polymer, such as pure PEO, as the matrix. While these offer good ionic conductivity, they suffer from insufficient mechanical strength and a tendency to crystallize. Some studies have attempted modification through crosslinking or blending, but these often sacrifice ionic conductivity for improved mechanical properties. Using triblock copolymers as the polymer matrix allows for synergistic optimization of ionic conductivity and mechanical properties. Taking a PEO-PPO-PEO triblock copolymer as an example, the PEO segment provides Li... + In terms of coordination and conduction, the PPO segments not only provide mechanical support but, more importantly, enhance chain mobility by disrupting the crystallinity of PEO. This block structure can also induce microphase separation, forming ion-conducting microchannels at the nanoscale, which, together with macroscopic magnetic composite fillers, form a multi-scale transport network. Compared to simple polymer blends, the chemical bonds of block copolymers ensure the stability of the phase structure and avoid phase separation problems during long-term use.

[0079] In some embodiments, the number-average molecular weight of the polymer matrix ranges from 1000 g / mol to 100000 g / mol, for example, 1000 g / mol to 3000 g / mol, 3000 g / mol to 5000 g / mol, 5000 g / mol to 8000 g / mol, 8000 g / mol to 10000 g / mol, 10000 g / mol to 15000 g / mol, 15000 g / mol to 20000 g / mol, 20000 g / mol to 50000 g / mol, or 50000 g / mol to 100000 g / mol.

[0080] In some embodiments, the polymer matrix includes ether oxygen units, and the molar ratio of lithium ions in the lithium salt to ether oxygen units in the polymer matrix is ​​0.01:1 to 0.2:1, for example, 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.06:1, 0.08:1, 0.1:1 or 0.2:1. This ratio ensures a sufficient lithium ion concentration while avoiding lithium salt precipitation.

[0081] Lithium salts, as the source of lithium ions, affect the ionic conductivity of composite electrolytes through their type and concentration. Lithium salts can be selected from inorganic lithium salts, organic lithium salts, or ionic liquid lithium salts, including lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(pentafluoroethylsulfonyl)imide, lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate, lithium hexafluoroarsenate, lithium bis(oxalate)borate, lithium difluoro(oxalate)borate, lithium tetra(fluorooxalate)phosphate, lithium difluorophosphate, lithium trifluoromethanesulfonate, and lithium di(trifluoromethanesulfonyl)methyl, etc.

[0082] Two or more lithium salts can be used in combination to achieve synergistic effects, such as combinations of LiTFSI and LiFSI, LiTFSI and LiPF6, and LiFSI and LiBF4, with a mixing molar ratio range of 10:90 to 90:10.

[0083] The total mass fraction of lithium salt in the solid electrolyte membrane ranges from 5 wt% to 40 wt%, for example, 5 wt%, 10 wt%, 15 wt%, 25 wt%, 30 wt%, 35 wt%, or 40 wt%.

[0084] The choice of initiator depends on the curing method. For UV curing processes, photoinitiators are used, including free radical photoinitiators such as 2-hydroxy-2-methylphenylacetone, 1-hydroxycyclohexylphenyl ketone, 2,2-dimethoxy-2-phenylacetophenone, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2,4,6-trimethylbenzoyl diphenylphosphine oxide, etc., or cationic photoinitiators such as triarylsulfonium salts, diaryliodoses, etc. For thermosetting processes, azo initiators such as azobisisobutyronitrile, azobisisoheptanenitrile, or peroxide initiators such as benzoyl peroxide, di-tert-butyl peroxide, etc., can be used.

[0085] In the polymerization precursor, the amount of initiator is 0.05wt% to 10wt% of the polymer matrix mass, for example 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 3wt%, 5wt%, 7wt%, 9wt% or 10wt%.

[0086] To improve the mechanical strength and dimensional stability of the composite electrolyte, the polymerization precursor also includes a crosslinking agent, such as diacrylate, triacrylate, tetraacrylate, dimethacrylate, or epoxy crosslinking agents. The amount of crosslinking agent used is 0.1wt% to 20wt% of the polymer matrix mass, for example, 0.1wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%, 5wt%, 10wt%, 13wt%, 15wt%, 18wt%, or 20wt%.

[0087] In the polymerization precursor, the solvent can be a polar aprotic solvent such as acetonitrile, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, or an ether solvent such as tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, or an alcohol solvent such as methanol, ethanol, isopropanol, butanol. A mixed solvent system can also be used.

[0088] When preparing the polymerization precursor, the mixing methods of each substance include mechanical stirring, with a stirring rate of 100 rpm to 3000 rpm and a stirring time of 0.5 h to 24 h; or ultrasonic dispersion, with an ultrasonic frequency of 20 kHz to 100 kHz, an ultrasonic power of 50 W to 500 W, and an ultrasonic time of 10 min to 2 h; or ball milling dispersion, with a ball milling speed of 100 rpm to 500 rpm and a duration of 0.5 h to 12 h; or high-speed shearing, with a speed of 1000 rpm to 30000 rpm and a duration of 5 min to 60 min.

[0089] The solid content of the prepared polymerization precursor is controlled at 20wt%~80wt%, for example 20wt%~30wt%, 30wt%~40wt%, 40wt%~60wt%, 60wt%~70wt%, and 70wt%~80wt%.

[0090] The viscosity of the polymerization precursor at 25°C is 100 mPa·s to 50000 mPa·s, for example, 100 mPa·s to 500 mPa·s, 500 mPa·s to 1000 mPa·s, 1000 mPa·s to 5000 mPa·s, 5000 mPa·s to 10000 mPa·s, 10000 mPa·s to 20000 mPa·s, 20000 mPa·s to 30000 mPa·s, 30000 mPa·s to 40000 mPa·s, or 40000 mPa·s to 50000 mPa·s.

[0091] To further optimize the overall performance of solid electrolyte membranes, various functional additives, such as plasticizers, inorganic fillers, interface modifiers, flame retardants, and stabilizers, can be added to the polymerization precursor.

[0092] Plasticizers include carbonates, ethers, sulfones, and nitriles, which are small molecule solvents that can improve ionic conductivity. The amount used accounts for 0 wt% to 30 wt% of the mass of the solid electrolyte membrane.

[0093] Inorganic fillers include Al2O3, SiO2, TiO2, ZrO2, BaTiO3, SrTiO3, LLZO, LLTO, etc., with particle sizes ranging from 10nm to 500nm. They can improve mechanical strength and are used in amounts ranging from 0wt% to 20wt% of the solid electrolyte membrane mass.

[0094] Interface modifiers include silane coupling agents, titanate coupling agents, aluminate coupling agents, etc., which can improve the interfacial bonding effect. The amount used accounts for 0wt%~5wt% of the solid electrolyte membrane mass.

[0095] Flame retardants, including phosphorus-based, fluorine-based, or inorganic flame retardants, can improve safety and are used in amounts ranging from 0 wt% to 15 wt% of the solid electrolyte membrane mass.

[0096] Stabilizers include antioxidants, ultraviolet absorbers, and heat stabilizers, which can extend the service life. The amount used accounts for 0 wt% to 3 wt% of the mass of the solid electrolyte membrane.

[0097] In a specific example, the preparation of the polymerization precursor can employ a multi-stage mixing process to ensure uniform dispersion of components. First, the polymer matrix is ​​dissolved in anhydrous acetonitrile to prepare a 15wt%–20wt% polymer solution, which is then stirred at 40°C for 2–4 hours under nitrogen protection until completely dissolved. Lithium salt is then added, and stirring continues for 1 hour. The initiator is added at 1.5wt% of the polymer matrix mass, and the mixture is stirred for 30 minutes in the dark. The magnetic composite filler is dispersed using a gradient feeding method, with the magnetic composite filler gradually added to the polymer solution in 3–5 batches. After each batch is added, ultrasonic dispersion (frequency 40kHz, power density 100W / L) is performed for 10–15 minutes, while simultaneously mechanical stirring (500rpm). The final content of the magnetic composite filler is controlled at 35±2wt%. The polymerization precursor is then processed through a three-roll mill 1–3 times, with the roller gap gradually reduced from 50μm to 10μm to ensure the absence of agglomerates. The prepared polymer precursor has a viscosity of 3000±500 mPa·s at 25℃ and a solid content of 50±2wt%.

[0098] In S103, the polymerization precursor can be coated into a film by methods such as blade coating, spin coating, dip coating, spray coating, roll coating, slot coating, gravure printing, or screen printing. The thickness of the wet film ranges from 10μm to 1000μm, for example, 10μm to 50μm, 50μm to 100μm, 100μm to 300μm, 300μm to 500μm, or 500μm to 1000μm.

[0099] A pulsed magnetic field is applied in the wet film state. The direction of the magnetic field can be perpendicular to the film plane or other angles can be selected as needed to make the magnetic composite filler oriented along the film thickness direction.

[0100] The magnetic field strength of the pulsed magnetic field is 0.2T~0.5T, the frequency is 0.1Hz~10Hz, the duty cycle is 40%~60%, and the duration is 30s~10min.

[0101] In section 104, the curing method is selected based on the type of initiator. For example, photoinitiators are cured using UV light, employing a light source with a wavelength of 200nm~800nm, which can be selected as a 320nm~400nm light source, with a light intensity of 1mW / cm². 2 ~500mW / cm 2 20mW / cm can be selected. 2 ~50mW / cm 2 The irradiation time is 10s~30min, selectable from 60s~180s, and curing can be carried out in air, inert gas, or vacuum atmosphere. Thermal curing can also be used, with a temperature of 40℃~200℃, selectable from 80℃~120℃, a time of 5min~24h, selectable from 30min~6h, and a heating rate of 0.5℃ / min~20℃ / min. Alternatively, electron beam curing can be used, with an accelerating voltage of 50kV~300kV and a dose of 10kGy~200kGy. Plasma curing can also be used, with a power of 50W~500W and a time of 30s~30min.

[0102] After curing, post-treatment can be performed to further optimize performance, including: vacuum drying at 40℃~120℃ for 0.1h~24h to remove residual solvent; and / or hot pressing at 40℃~150℃ and 0.1MPa~10MPa to improve density. Surface modification can also be performed, such as plasma, corona, and chemical treatments.

[0103] The thickness of the solid electrolyte membrane ranges from 50 μm to 200 μm, for example, 50 μm to 80 μm, 80 μm to 120 μm, 120 μm to 150 μm, or 150 μm to 200 μm.

[0104] In a specific example, continuous film formation of the polymerization precursor utilizes a specialized magnetic field-assisted coating production line. The polymerization precursor is uniformly coated onto a release PET substrate through a slit coating head at a coating speed of 2 m / min to 10 m / min. The wet film thickness is precisely controlled at 200 ± 10 μm by adjusting the coating gap and slurry supply rate. The coated wet film immediately enters the magnetic field induction zone, which is equipped with an array of pulsed electromagnets with the magnetic field direction perpendicular to the film surface. The pulsed magnetic field generator is controlled by IGBTs, allowing for precise adjustment of the magnetic field strength, frequency, and duty cycle. The magnetic field zone is 3 meters long, and at a conveying speed of 5 m / min, the film material resides in the magnetic field for 36 seconds to achieve the directional alignment of the magnetic composite filler. Magnetic field uniformity is monitored in real-time by multi-point Hall sensors, with deviations controlled within ±5%. The curing zone is immediately adjacent to the magnetic field induction zone, employing an LED-UV light source array with a wavelength of 365 nm and a light intensity distribution uniformity ≥90%. Curing is carried out under a nitrogen protective atmosphere, with the oxygen content controlled below 100 ppm to avoid oxygen-induced polymerization inhibition. The curing area is divided into three sections: pre-curing section (light intensity 15mW / cm²). 2 40s), main curing section (light intensity 30mW / cm²) 2 60s), post-curing stage (light intensity 20mW / cm²) 2 (20s), the crosslinking density distribution was optimized through a gradient curing strategy.

[0105] The coating stage consisted of a coating speed of 5±0.1 m / min, a wet film thickness of 200±10 μm, and a coating temperature of 25±2℃. The magnetic field induction stage involved a magnetic field strength of 0.35±0.02 T, a pulse frequency of 2±0.1 Hz, a duty cycle of 50±2%, and an action length of 3 m. The curing stage used a light source with a wavelength of 365±5 nm and a light intensity of 30±2 mW / cm². 2 The irradiation time was 120±5s, and the nitrogen flow rate was 50±5L / min.

[0106] The cured solid electrolyte membrane proceeds to the post-processing stage. Residual solvents are removed in a continuous vacuum drying oven at 80℃, a vacuum of -0.09MPa, and a residence time of 30 minutes. Subsequently, it undergoes densification treatment using a hot roller press at 90℃ and a linear pressure of 50N / cm, allowing for precise control of the membrane thickness to within 100±5μm.

[0107] The surface of the solid electrolyte membrane can be selectively plasma-treated to improve the interfacial adhesion with the electrode. Plasma treatment parameters: power 100W, argon flow rate 20 sccm, treatment time 30 s. The treated solid electrolyte membranes are quality controlled using an online thickness detection system (accuracy ±1 μm) and a rapid ionic conductivity detection system. Qualified products are wound up, packaged, and stored in a drying chamber (dew point ≤ -40℃).

[0108] In S12, the positive electrode sheet may include a positive current collector and a positive electrode material layer covering the surface of the positive current collector.

[0109] The positive current collector is selected from aluminum foil or carbon-coated aluminum foil.

[0110] The positive electrode material layer can be formed by drying and curing the positive electrode slurry. The composition of the positive electrode slurry may include 70wt%~95wt% of positive electrode active material, 1wt%~10wt% of binder, 1wt%~10wt% of conductive agent and 5wt%~30wt% of solid electrolyte component. The solid electrolyte component may be the magnetic composite filler provided in the embodiments of this application, or other ionic conductors such as LLZO, LLTO, sulfide electrolyte, etc. Its function is to build a continuous ion conduction network inside the positive electrode sheet and reduce the interfacial impedance of the positive electrode / solid electrolyte membrane.

[0111] Positive electrode active materials include layered oxide positive electrode materials, spinel structure positive electrode materials, polyanion positive electrode materials, lithium-rich manganese-based positive electrode materials, transition metal fluoride positive electrode materials, and organic positive electrode materials. Among these, the chemical formula of layered oxide positive electrode materials can be Li... x MO2, where M is a combination of transition metal elements such as Ni, Co, Mn, and Al. A typical example of a spinel-structured cathode material is LiMn2O4, which exhibits high safety and good rate performance. Polyanion cathode materials have the general formula Li... x MPO4 (where M represents Fe, Mn, Co, V, etc.), with LiFePO4 being widely used due to its excellent cycle stability and safety. Lithium-rich manganese-based cathode materials (Li... x M y Mn z O2 (where M represents Ni, Co, etc.) has attracted attention due to its high specific capacity and high safety. Transition metal fluoride (such as FeF3, CoF3) cathode materials have high voltage plateaus and high energy densities. Organic cathode materials (such as polymers containing carbonyl or quinone groups) are potential candidates due to their environmental friendliness and structural designability.

[0112] The binder can be a polymer with ion conductivity, such as PVDF-HFP or PEO.

[0113] Conductive agents can be selected from carbon black, carbon nanotubes, graphene, etc.

[0114] The positive current collector is aluminum foil or carbon-coated aluminum foil.

[0115] The negative electrode sheet may include a negative electrode current collector and a negative electrode material layer covering the surface of the negative electrode current collector.

[0116] The negative electrode current collector is usually made of copper foil, but surface-modified copper foil (such as carbon-coated copper foil) or other special materials can also be used to optimize lithium deposition behavior and interface stability.

[0117] The negative electrode material layer can be formed by drying and curing negative electrode slurry. The composition of negative electrode slurry may include 70wt%~95wt% of negative electrode active material, 1wt%~10wt% of binder and 1wt%~10wt% of conductive agent.

[0118] The anode active material can be a traditional anode material such as graphite, silicon, silicon-carbon composite material, or lithium titanate.

[0119] For solid-state lithium metal batteries, the anode can be made of lithium metal-based materials, including various forms and modification strategies. As a basic form, pure lithium metal anodes typically exist as lithium foil or lithium layers, with thicknesses ranging from the traditional 50μm~500μm to ultrathin 5μm~50μm. Ultrathin lithium foil designs help improve battery energy density and reduce dead lithium formation. In terms of morphology optimization, surface-structured lithium metals (such as lithium foils with specific micro / nano structures) and three-dimensional lithium metals (such as porous lithium or lithium filled in a conductive framework) can effectively reduce local current density, promote uniform deposition, and significantly suppress dendrite growth. Lithium alloy anodes are an important development direction, including lithium-main group metal alloys (Li-Al, Li-Si, Li-Sn, Li-Ge, etc.) and lithium-transition metal alloys. These alloys, by forming a stable phase with lithium, can mitigate dendrite growth and alleviate volume expansion problems. Lithium-based composite anodes, such as lithium-carbon composites (composites of lithium with carbon nanotubes, graphene, or porous carbon), enhance anode performance by leveraging the conductivity and structural stability of carbon materials. Artificial SEI film technology significantly improves interfacial stability by pre-constructing a protective layer on the lithium surface. These protective layers can be organic materials (such as conductive polymers), inorganic materials (such as LiF, Li3N, Al2O3, etc.), or organic / inorganic composites.

[0120] In solid-state battery systems, to improve the interfacial contact between the negative electrode and the solid electrolyte, an interfacial buffer layer, such as a soft metal like gold or silver, can be coated on the surface of the negative electrode, or an in-situ polymerized gel electrolyte can be used as the interfacial layer.

[0121] In some embodiments, a modified interface layer may be coated on both sides of the solid electrolyte membrane to further optimize the electrode / solid electrolyte membrane interface. The modified interface layer may be coated with a polymer solution containing lithium salt or formed by in-situ polymerization. Its composition may include polymers such as PEO and PVDF-HFP, as well as lithium salts such as LiTFSI and LiFSI, with a thickness of 1 μm to 10 μm.

[0122] In a specific example, the initial cell assembly needs to be carried out in a dry chamber environment (dew point ≤ -40℃). The positive electrode is prepared using a traditional coating process, where a mixture of positive electrode active material, conductive agent, binder, and solid electrolyte powder is coated onto aluminum foil, dried, and then rolled to the required thickness and compaction density. The negative electrode is prepared using a process selected based on the material system. For lithium metal negative electrodes, lithium foil can be used directly, or a lithium layer can be prepared on copper foil through electroplating / evaporation.

[0123] Battery assembly employs a hot-pressing composite process, where the positive electrode, solid electrolyte membrane, and negative electrode are stacked sequentially and composited in a hot press. Hot-pressing parameters are: temperature 80℃~100℃, pressure 5MPa~10MPa, and time 5min~10min. During hot pressing, moderate interdiffusion occurs between the solid electrolyte membrane and the electrode interface, forming good interfacial contact. For pouch cells, the hot-pressed cells are placed in an aluminum-plastic film and vacuum-sealed before electrochemical testing. For coin cells, they can be directly assembled in a glove box, applying appropriate pressure (~3MPa) to ensure interfacial contact.

[0124] The assembled initial battery cell requires pretreatment activation. It is left to stand at 45℃ for 12-24 hours to allow full contact between the solid electrolyte membrane and the electrode interface. Then, the first charge-discharge cycle is performed using a small current (0.05C-0.1C). The charging cutoff voltage is determined based on the positive electrode material (e.g., 4.3V for NCM, 3.65V for LFP), and the discharging cutoff voltage is 2.5V-3.0V. After 3-5 activation cycles, the solid-state secondary battery is ready for normal charge-discharge testing.

[0125] Through the above-described process flow, the magnetic field-induced oriented composite solid electrolyte membrane provided in this application embodiment can achieve technology transfer from laboratory to industrialization. The prepared solid-state secondary battery exhibits excellent electrochemical performance, including high ionic conductivity (>10 at room temperature). -3 S / cm, low interface impedance (<100Ω·cm) 2 With its wide electrochemical window (>4.5V) and long cycle life (>1000 cycles, capacity retention >80%), it lays a solid foundation for the commercial application of next-generation high-performance solid-state batteries.

[0126] The solid electrolyte membrane prepared in this application can be applied not only to secondary batteries, such as lithium-ion batteries and lithium metal batteries, but also, through simple component adjustments, to lithium-sulfur batteries, lithium-air batteries, sodium-ion batteries (by replacing the lithium salt with the corresponding sodium salt), other alkali metal batteries such as potassium, rubidium, and cesium batteries, and multivalent ion batteries such as magnesium, calcium, zinc, and aluminum batteries. Furthermore, this solid electrolyte membrane can also be used in electrochemical devices such as solid-state capacitors, supercapacitors, electrochromic devices, and sensors. By adjusting the direction of the magnetic field, functional membranes with anisotropic ion conduction properties can also be prepared to meet the needs of specific application scenarios.

[0127] In the secondary battery manufacturing method provided in this application embodiment, a magnetic composite filler including an ion-conducting core is prepared. The surface of the ion-conducting core is sequentially coated with a magnetic functional layer and a protective layer. The ion-conducting core provides a rapid ion transport channel. The magnetic functional layer, coated on the surface of the ion-conducting core, endows the magnetic composite filler with magnetic field responsiveness. The protective layer, covering the outside of the magnetic functional layer, plays a triple role of electrochemical isolation, interface optimization, and dispersion stabilization. In the polymerization precursor, the polymer matrix serves as the continuous phase of the solid electrolyte membrane, providing not only mechanical support but also participating in ion conduction. The lithium salt serves as the source of lithium ions, and the initiator is used to initiate the polymerization reaction to solidify the polymerization precursor into a solid electrolyte membrane. The polymer precursor is coated into a film under a pulsed magnetic field. The magnetic composite filler is oriented along the thickness direction of the film by inducing the magnetic field. The essential difference from conventional electrospinning and freeze-drying orientation technology is that it adopts non-contact magnetic field induction, which avoids the damage of physical stress to the magnetic composite filler. At the same time, the "drive-relaxation" cycle mechanism of the pulsed magnetic field can effectively prevent excessive particle agglomeration and promote the formation of an ordered chain structure. It has good process controllability and scalability potential. Compared with the "one-step" of constant magnetic field, the "gradual optimization" strategy of pulsed magnetic field can form through ion channels with fewer defects and better continuity.

[0128] Through a three-layer core-shell structure and a synergistic design induced by a pulsed magnetic field, key problems faced by traditional composite solid electrolytes, such as tortuous ion conduction paths, high interfacial impedance, and difficult processing, have been systematically solved, providing a new technological path for the development of high-performance solid-state secondary batteries. Solid-state secondary batteries are expected to achieve comprehensive improvements in energy density, cycle life, and safety performance, enabling high-capacity applications suitable for long-term energy storage, such as energy storage systems that can operate continuously for 4 to 8 hours at rated power. This provides crucial technological support for the development of next-generation high-performance electrochemical energy storage systems.

[0129] Conventional magnetic field-induced composite electrolytes often employ simple physical mixtures or bilayer coating structures of magnetic materials and ion conductors. For example, a bilayer structure using inorganic solid electrolytes to coat magnetic nanowires, or a simple mixture of Fe3O4 and LLZO. While these methods can achieve magnetic field response, they suffer from side reactions caused by direct contact between the magnetic material and the electrolyte, as well as the drawback of magnetic particle agglomeration affecting ion conduction.

[0130] This application proposes a three-layer core-shell structure design consisting of an ion-conducting core, a magnetic functional layer, and a protective layer. This functional layering achieves the synergistic integration of "fast ion conduction + magnetic field response + interface stability," identifying and resolving a fundamental contradiction faced by magnetic composite fillers: the magnetic functional layer provides magnetic response but may undergo side reactions with lithium, while the protective layer not only provides electrochemical isolation but also forms a strong interfacial bond with the polymer matrix. This design concept of "functional division of labor + interface synergy" organically unifies the previously mutually restrictive multiple functions through ingenious structural design, fundamentally breaking through the technical bottlenecks of conventional technologies in magnetic filler applications.

[0131] Traditional magnetic field induction techniques generally employ a constant magnetic field, which can drive the orientation of magnetic particles, but it easily leads to excessive particle aggregation, forming rigid agglomerates that hinder ion conduction. Other related techniques use electric field induction, but this requires the filler to possess electrical response characteristics, and uneven electric field distribution can result in inconsistent orientation effects.

[0132] This application proposes a pulsed magnetic field induction technique, which achieves precise control over the arrangement of magnetic composite packings through the periodic alternation of a "driving period" and a "relaxation period." During the driving period, the magnetic field provides the orientation driving force; during the relaxation period, the magnetic composite packings undergo positional fine-tuning under Brownian motion, breaking the initial rigid aggregation and forming a more ordered and appropriately contacted chain structure. The essence of this dynamic control mechanism is to utilize the kinetic characteristics of colloidal systems, finding a balance between thermodynamic driving and kinetic relaxation through clever time-scale design. Compared to the "one-step" approach of a constant magnetic field, the "gradual optimization" strategy of the pulsed magnetic field can form through-type ion channels with fewer defects and better continuity.

[0133] Conventional techniques often focus on optimizing ion transport at a single scale, such as increasing filler content or improving filler dispersion, but neglect the collaborative construction of multi-scale transport networks. In randomly distributed filler systems, ion transport paths are tortuous and discontinuous, making it difficult to form an effective permeation network even with high filler content.

[0134] This application embodiment constructs a three-dimensional synergistic transport network consisting of "fast ion channels + interfacial conductive layer + polymer bulk conduction" through magnetic field-induced directional alignment. The innovation of this multi-level transport mechanism lies in the fact that the primary channels are formed by directionally aligned magnetic composite fillers, providing the main fast transport path (σ>10). -4 The secondary channels, consisting of the interface region between the protective layer and the polymer matrix, utilize the interfacial effect to reduce the activation energy. The tertiary channels, provided by the polymer matrix, ensure the continuity of ion conduction. These three levels of transport channels complement and work synergistically, achieving excellent ionic conductivity even with low filler content. This fundamentally changes the traditional perception that "high conductivity requires high filler content."

[0135] Conventional filler orientation techniques such as electrospinning require high voltage and are difficult to control the uniformity of fiber orientation; cryogenic casting is complex and has poor batch-to-batch consistency; and stretching orientation can easily lead to filler breakage and matrix molecular chain orientation problems. These contact methods all suffer from narrow process windows and difficulty in scaling up.

[0136] The magnetic field induction technology provided in this application has unique advantages such as non-contact operation, precise control, and ease of continuous production. By integrating a pulsed magnetic field generator into the coating production line, continuous roll-to-roll production can be achieved, with a processing width of over 300mm. More importantly, the magnetic field parameters (intensity, frequency, duty cycle) can be adjusted in real time, allowing for process optimization based on slurry characteristics and product requirements. The synergistic effect of rapid curing and magnetic field induction ensures the rapid "freezing" of the oriented structure, avoiding structural relaxation that may occur during the curing process. This process design not only improves production efficiency but, more importantly, ensures the consistency and repeatability of product quality, clearing technical obstacles for the industrial application of composite solid electrolytes.

[0137] In summary, the manufacturing method of the secondary battery provided in this application has achieved innovations in material design and structural construction, and breakthroughs in process route and preparation concept. Through the synergistic design of a three-layer core-shell structure and pulsed magnetic field-induced structure, it systematically solves key problems faced by traditional composite solid electrolytes, such as tortuous ion conduction paths, high interfacial impedance, and difficult processing, providing a new technical path for the development of high-performance solid-state batteries. Solid-state secondary batteries are expected to achieve comprehensive improvements in energy density, cycle life, and safety performance, realizing high-capacity solid-state secondary batteries suitable for long-term energy storage applications, such as energy storage systems that can operate continuously for 4 to 8 hours at rated power, providing key technical support for the development of next-generation high-performance electrochemical energy storage systems.

[0138] Accordingly, another embodiment of this application also provides a secondary battery, which can be prepared using the manufacturing method of the secondary battery provided in the above embodiments. For parts that are the same as or corresponding to the previous embodiment, please refer to the corresponding descriptions in the foregoing embodiments; detailed descriptions will not be repeated below.

[0139] The secondary battery of this application embodiment includes: a casing, which contains a positive electrode, a solid electrolyte, and a bare cell formed by winding or stacking a negative electrode; wherein the solid electrolyte includes a magnetic composite filler, a lithium salt, and an electrolyte matrix, the magnetic composite filler being oriented in the electrolyte matrix along the direction from the positive electrode to the negative electrode, the magnetic composite filler including an ion conductor core, the surface of the ion conductor core being sequentially coated with a magnetic functional layer and a protective layer, the material of the magnetic functional layer including a magnetic material, and the material of the protective layer including an oxide; the lithium salt is dispersed in the electrolyte matrix; the electrolyte matrix is ​​formed by the polymerization reaction of a polymer matrix and an initiator.

[0140] Secondary batteries can be classified into cylindrical batteries, prismatic batteries, and pouch batteries according to their battery type.

[0141] According to some embodiments of this application, another aspect of this application provides a battery device, including a secondary battery prepared by the manufacturing method of the secondary battery in the above embodiments, or the secondary battery in the above embodiments. The battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

[0142] According to some embodiments of this application, another aspect of this application provides an energy storage device, including the battery device in the above embodiments, the battery device being used to store electrical energy.

[0143] Energy storage devices include, but are not limited to, energy storage containers, energy storage cabinets, energy storage power stations, energy storage battery packs, or portable energy storage systems.

[0144] Energy storage devices may also include energy management systems (EMS), battery management systems (BMS), and energy storage converters (PCS).

[0145] According to some embodiments of this application, this application also provides an electrical device, including the battery device in the above embodiments, the battery device being used to provide electrical energy.

[0146] Electrical devices include, but are not limited to, mobile phones, tablets, laptops, electric toys, power tools, electric vehicles, electric cars, ships, spacecraft, etc. Among them, electric toys can include stationary or mobile electric toys, such as game consoles, electric car toys, electric ship toys, and electric airplane toys, etc. Spacecraft can include airplanes, rockets, space shuttles, and spacecraft, etc.

[0147] The following are specific embodiments illustrating this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0148] The examples and comparative examples were prepared in the following manner: (1) Preparation of ionic conductor cores: according to Li 1.3 Al 0.3 Ti 1.7 To obtain the stoichiometric ratio of (PO4)3, 1.442 g of Li2CO3, 0.765 g of Al2O3, 6.790 g of TiO2, and 10.358 g of NH4H2PO4 were weighed and thoroughly ground in an agate mortar for 30 min, then transferred to an alumina crucible. The crucible was placed in a muffle furnace and heated to 900 °C at a heating rate of 5 °C / min, and held at that temperature for 6 h for solid-phase reaction. The cooled product was then ball-milled with the following parameters: rotation speed 400 rpm, ball-to-material ratio 10:1, and milling time 6 h, yielding LATP powder with a D50 of approximately 500 nm. Laser particle size analysis showed a particle size distribution D90 / D10 < 1.8, indicating uniform particle size distribution.

[0149] (2) Coating of the magnetic functional layer: 10g of LATP powder was dispersed in 200mL of deionized water and ultrasonically dispersed for 30min to form a uniform suspension. Under nitrogen protection, a mixed solution containing 2.78g of FeSO4·7H2O and 5.41g of FeCl3·6H2O (Fe 2+ :Fe 3+ The mixture was stirred vigorously in a 65°C constant temperature water bath (molar ratio 1:2). Ammonia was slowly added dropwise to adjust the pH to 10.5. The color of the reaction solution changed from yellowish-brown to black, indicating the formation of Fe3O4. After continuing the reaction for 2 hours, the product was collected by magnetic separation, washed three times each with deionized water and ethanol, and then vacuum dried at 80°C for 12 hours to obtain Fe3O4-coated LATP particles (Fe3O4@LATP).

[0150] (3) Coating of the protective layer: 5g of Fe3O4@LATP particles were dispersed in 100mL of anhydrous ethanol, and 5mL of deionized water and 2mL of ammonia were added to form a uniform dispersion. 1.0mL of TEOS ethanol solution (TEOS:ethanol volume ratio 1:4) was slowly added dropwise at room temperature, with the dropping rate controlled at 0.5mL / min. After the addition was completed, the reaction was stirred for 6h to allow TEOS to fully hydrolyze and condense to form a SiO2 coating layer. After the reaction was completed, the product was separated by centrifugation, washed three times with ethanol, and vacuum dried at 120℃ for 6h to finally obtain m-LATP (SiO2@Fe3O4@LATP) magnetic composite filler with a three-layer core-shell structure.

[0151] (4) Preparation of polymerization precursors: According to the formulation in Table 1 of the experimental design, weigh the corresponding masses of m-LATP magnetic composite filler, PEO-PPO-PEO triblock copolymer, LiTFSI lithium salt and Irgacure 819 photoinitiator. Taking Example 1 as an example, weigh 3.5g of m-LATP, 6.0g of PEO-PPO-PEO (PEO:PPO=70:30), and 0.45g of LiTFSI ([Li + [EO] = 0.05 g and 0.09 g of photoinitiator (1.5 wt% of PEO-PPO-PEO mass) were added to 50 mL of anhydrous acetonitrile. The mixture was first magnetically stirred at 40 °C until completely dissolved. Then, lithium salt was added and stirring continued for 1 h. Finally, m-LATP magnetic composite filler and photoinitiator were added. Ultrasonic dispersion (40 kHz, 100 W) and mechanical stirring (500 rpm) were alternated, each method lasting 15 min, repeated three times to ensure uniform dispersion of the filler, resulting in a polymerization precursor with a solid content of approximately 50 wt% and a viscosity of 3000 ± 500 mPa·s.

[0152] (5) Preparation of solid electrolyte membrane: The prepared polymer precursor was uniformly coated onto the PET release film by a blade coating method. The blade gap was set to 250 μm, and the coating speed was 5 cm / s. For embodiments requiring magnetic field induction, the coated wet film was immediately transferred to the magnetic field device. The pulsed magnetic field parameters were set according to Experimental Design Table 2. For example, in Example 1, a magnetic field strength of 0.35 T, a frequency of 2 Hz, a duty cycle of 50%, a magnetic field direction perpendicular to the film surface, and an action time of 60 s were used. At the same time or after the magnetic field action (as set according to Experimental Design Table 2), a 365 nm UV light source was used for irradiation with a light intensity of 30 mW / cm². 2 The irradiation time is 120 seconds, and curing is completed under nitrogen protection.

[0153] (6) Post-treatment of solid electrolyte membrane: After curing, the solid electrolyte membrane was dried in a vacuum oven at 80°C for 2 hours to remove residual solvent, and then peeled off from the PET release film to obtain a self-supporting solid electrolyte membrane with a thickness of about 100 μm. For thermosetting comparative example 6, curing was completed by holding at 60°C for 6 hours, and other steps were the same.

[0154] In the embodiments and comparative examples of this application, the secondary battery adopts a 3.8Ah stacked soft-pack structure.

[0155] The positive electrode uses NCM811 (LiNi) 0.8 Co 0.1 Mn 0.1 O2 is used as the positive electrode material. The positive electrode slurry is formulated with NCM811, conductive agent Super P, carbon nanotubes (CNTs), and binder PVDF in a mass ratio of 92:4:1:3, with an areal density of 20±0.5 mg / cm³. 2 The compacted density is 3.3 g / cm³. 3 It is coated on an aluminum foil with a thickness of 15μm.

[0156] The negative electrode is a 50μm thick lithium metal foil.

[0157] Table 1

[0158] Table 2

[0159] In the manufacturing process of secondary batteries, positive electrode sheets, solid electrolyte membranes, and negative electrode sheets are stacked sequentially to form a multi-layer stacked structure, and then encapsulated with an aluminum-plastic film. To improve the interfacial contact between the solid electrolyte membrane and the electrodes, a small amount of interfacial wetting agent can be added before encapsulation. The assembled secondary battery is vacuum dried at high temperature to remove residual solvents, and then subjected to processes such as settling and formation to produce an all-solid-state lithium metal secondary battery. The formation adopts a low-current stepped charging strategy, with the first cycle gradually activating at 0.05C~0.2C, and the charge / discharge voltage window is 2.8V~4.3V.

[0160] The examples and comparative samples underwent ionic conductivity testing, lithium-ion transference number testing, electrochemical stability window testing, interface stability testing, tensile properties testing, 25°C cycle capacity retention testing, 45°C cycle capacity retention testing, rate performance testing, 10°C low-temperature performance testing, and 60°C high-temperature storage performance testing. All data are based on the average of 3 to 5 parallel sample tests, with a typical error range of 5% to 10%.

[0161] Ionic conductivity testing: The ionic conductivity of the solid electrolyte membrane was determined by electrochemical impedance spectroscopy (EIS) at four temperatures: -10℃, 25℃, 45℃, and 60℃. The solid electrolyte membrane was sandwiched between two stainless steel blocking electrodes at 10℃. -2 Hz~10 6 Impedance testing was conducted within the Hz frequency range. Ionic conductivity is a key parameter measuring the ionic conduction capability of solid electrolytes, expressed in millisiemens per centimeter (mS / cm). Higher conductivity indicates better ionic conductivity of the electrolyte, thereby improving battery power performance and temperature adaptability. Ionic conductivity is calculated using the formula σ=L / (R×S), where L is the film thickness (μm), R is the bulk resistance (Ω), and S is the electrode area (cm²). 2 S=2.01cm 2 .

[0162] Lithium-ion transport number (LTU) test: The LTU was determined using the Bruce-Vincent method at 25°C. A Li||solid electrolyte membrane||Li symmetric cell was assembled, a 10mV DC voltage was applied, and the current change over time was recorded until steady state was reached (typically 2-4 hours). The interfacial impedance was measured before and after polarization. The LTU reflects the contribution of lithium ions to the total ion current and is an important indicator for evaluating the selective transport of ions in solid electrolytes. A LTU closer to 1 indicates higher lithium-ion transport efficiency of the solid electrolyte, which is beneficial for reducing concentration polarization and improving battery rate performance.

[0163] Electrochemical stability window testing: The electrochemical stability window of the solid electrolyte was determined using linear sweep voltammetry (LSV) at 25 °C. An asymmetric Li||solid electrolyte membrane||SS cell was assembled, and the voltage was scanned from the open-circuit voltage to 6.0 V (vs. Li / Li) at a scan rate of 0.5 mV / s. + The electrochemical stability window is the voltage range within which a solid electrolyte can operate stably. A wider window allows for better matching with high-voltage cathode materials. The recorded oxidation-decomposition current density reached 1 μA / cm². 2 The voltage value at that time is taken as the oxidation decomposition potential.

[0164] Interface stability test: At 25℃, a Li||solid electrolyte membrane||Li symmetric cell was assembled, and the stability was tested at 0.5 mA / cm². 2 Constant current charge-discharge cycle tests were conducted at the specified current density. Each charge-discharge cycle lasted 0.5 hours, with a total cycle time of 500 hours. The overpotential was monitored over time. Interface stability tests were performed to evaluate the interfacial compatibility between the solid electrolyte and the lithium metal anode, as well as its ability to suppress lithium dendrite growth. A stable voltage plateau and a small overpotential increase indicate that the interface is stable and can effectively suppress lithium dendrite growth.

[0165] Tensile property testing: At 25℃, the solid electrolyte membrane was cut into standard dumbbell-shaped strips (according to GB / T1040 standard) and tested on a universal testing machine at a tensile rate of 5 mm / min. The stress-strain curves were recorded, and Young's modulus (GPa), tensile strength (MPa), and elongation at break (%) were calculated. Mechanical properties are important indicators for the practical application of solid electrolyte membranes. Good mechanical strength can suppress lithium dendrite penetration, while moderate flexibility is beneficial for adapting to changes in electrode volume. Five parallel samples were tested for each sample, and the average value was taken.

[0166] 25℃ Cyclic Capacity Retention Test: At 25℃, the battery was charged at a constant current of 1C to the upper limit voltage of 4.3V, then charged at a constant voltage to a current of 0.05C, and finally discharged at a constant current of 1C to the lower limit voltage of 2.8V. The discharge capacity was recorded at the 200th and 500th cycles. The capacity retention rate was calculated as (discharge capacity at the nth cycle / discharge capacity at the first cycle) × 100%. The initial coulombic efficiency was also recorded.

[0167] 45℃ Cyclic Capacity Retention Test: Cyclic tests were conducted at 45℃ using the same charge-discharge regime as at 25℃. The discharge capacity was recorded at the 100th and 200th cycles, and the capacity retention rate was calculated. High-temperature cycling tests are used to evaluate the stability of the solid electrolyte at high temperatures and the battery's high-temperature adaptability.

[0168] Rate performance testing: At 25℃, a fixed charging rate of 0.5C (constant current and constant voltage charging to 4.3V, cutoff at 0.05C) was used. Discharge rates were set at 0.2C, 0.5C, 1C, 2C, and 3C, with 5 cycles at each rate. The capacity retention rate at each rate was calculated using the 0.2C discharge capacity as a baseline (100%). Rate performance reflects the battery's fast charging and discharging capability and is an important indicator for evaluating the ion conduction performance of solid-state electrolytes.

[0169] -10℃ Low Temperature Performance Test: At -10℃, the electrolyte was charged at a constant current of 0.2C to 4.3V, then charged at a constant voltage to a current of 0.05C, and finally discharged at a constant current of 0.2C to 2.8V. The discharge capacity was recorded and compared with the discharge capacity at 25℃ at 0.2C. The low temperature capacity retention rate (%) was calculated as (low temperature discharge capacity / room temperature discharge capacity) × 100%. Low temperature performance is a key indicator for evaluating the ability of solid electrolytes to operate in extreme environments.

[0170] 60℃ High-Temperature Storage Performance Test: At 60℃, the battery was charged at a constant current of 0.5C to the upper limit voltage of 4.3V, then charged at a constant voltage to a current of 0.05C, and then discharged at a constant current of 0.5C to the lower limit voltage of 2.8V. The discharge capacity was recorded as the initial capacity C1. The battery was then fully charged again using the same procedure to ensure it was at 100% SOC. The fully charged battery was stored at 60℃ for 30 days. After storage, the battery was left at room temperature for at least 2 hours, then discharged at a constant current of 0.5C to the lower limit voltage. The capacity C2 was recorded, and the capacity retention rate (%) was calculated as (C2 / C1) × 100%. Subsequently, three charge-discharge cycles were performed at room temperature, and the third discharge capacity C3 was recorded. The capacity recovery rate (%) was calculated as (C3 / C1) × 100%.

[0171] These test methods aim to comprehensively evaluate the overall performance of the solid electrolyte membranes prepared in each embodiment and comparative example, and indirectly verify the effectiveness of the magnetic field-induced directional alignment technology through performance differences. The test results are shown in Tables 3 and 4.

[0172] Table 3

[0173] Table 4

[0174] Experimental results fully demonstrate the crucial role of magnetic field-induced directional alignment technology in improving the ion conductivity of solid electrolyte membranes. By comparing the test data of Example 1 with Comparative Examples 1 and 2, the performance leap brought about by the directional structure can be clearly observed. The room temperature ionic conductivity of Example 1 reaches 1.28 × 10⁻⁶. -3 S / cm, compared to the traditional random distribution comparative example 1 (1.85×10⁻⁶). -4 The S / cm ratio of Example 1 was improved by approximately 7 times, a significant improvement that directly validates the design concept of constructing a through-type ion conduction channel in the embodiments of this application. More importantly, Example 1, compared to Comparative Example 2 (with magnetic composite filler but without a magnetic field, 2.58 × 10⁻⁶), showed a significant improvement. -4 The S / cm ratio still shows an improvement of about 5 times. This comparison excludes the contribution of the improved properties of the magnetic composite filler itself, and clearly proves that magnetic field-induced directional alignment is a necessary condition for achieving high ionic conductivity.

[0175] Temperature dependence analysis showed that the conductivity of all samples conformed to the Arrhenius relationship with temperature, but Example 1 maintained its advantage at all temperature points. Particularly at a low temperature of -10°C, Example 1 still maintained a conductivity of 3.85 × 10⁻⁶. - 4 The conductivity of Example 1 is 4.25 × 10⁻⁶ S / cm, while that of Comparative Example 1 is only 4.25 × 10⁻⁶. -5The difference in conductivity (S / cm) increased to approximately nine times. This significant improvement in low-temperature performance indicates that the directionally aligned, continuous fast ion channels effectively reduce the activation energy of ion transport and mitigate the adverse effects of polymer chain freezing on ion conduction at low temperatures. At a high temperature of 60°C, the conductivity of Example 1 reached 3.28 × 10⁻⁶. -3 The S / cm ratio is close to that of liquid electrolytes, fully demonstrating the application potential of the embodiments of this application over a wide temperature range.

[0176] Comparative Example 3 was treated with a constant magnetic field, and its room temperature conductivity was 7.65 × 10⁻⁶. -4 While the S / cm ratio is significantly improved compared to Comparative Example 2 without a magnetic field, it is still significantly lower than Example 1 using a pulsed magnetic field. This difference stems from the different influence mechanisms of the two magnetic field modes on the alignment dynamics of the magnetic composite filler. Under a constant magnetic field, the magnetic composite filler tends to form rigid aggregates after initial rapid aggregation, with overly tight interparticle contact, which hinders the penetration of the polymer matrix and interfacial bonding. In contrast, the "drive-relaxation" cycle mechanism of the pulsed magnetic field allows particles to form initial orientation during the magnetic drive period and fine-tune their position through Brownian motion during the relaxation period, ultimately forming an ordered chain structure with moderate contact and fewer defects.

[0177] According to the interface stability test results, Example 1 is at 0.5 mA / cm 2 The first example can maintain stable cycling for over 500 hours at the current density, while Comparative Example 3 can only maintain it for 380 hours. This indicates that the directional structure formed by the pulsed magnetic field is not only superior in ion conduction, but also has significant advantages in suppressing lithium dendrite growth and maintaining interface stability. Cycling performance data also confirms this point; after 500 cycles, Example 1 still retains 86.5% of its capacity, while Comparative Example 3 retains 78.2%, a difference of 8.3 percentage points.

[0178] The experimental results of Comparative Example 4 strongly demonstrate the indispensability of the protective layer in the three-layer core-shell structure. Although the initial conductivity of Comparative Example 4 (Fe3O4@LATP bilayer structure) reaches 8.50 × 10⁻⁶... -4 The S / cm ratio was close to that of Example 1, but its interface stability and cycling performance both showed catastrophic degradation. In the interface stability test, Comparative Example 4 failed after only 150 hours, and its capacity retention dropped to 50.0% after 200 cycles at 45°C. Its capacity recovery rate after storage at 60°C was only 78.5%, both the worst among all samples. This contradictory phenomenon of "high conductivity - low stability" reveals the serious side reaction problems caused by direct exposure of Fe3O4.

[0179] In-depth analysis reveals that direct contact between Fe3O4 and lithium metal triggers a continuous interfacial reaction. While the resulting byproducts may exhibit ion-electron mixed conductivity in the short term (explaining the higher apparent conductivity of Comparative Example 4), this unstable interface leads to continuous consumption of active lithium and a cumulative increase in impedance, ultimately resulting in battery failure. In contrast, Example 1, through effective isolation by the SiO2 protective layer, achieves long-term stability while maintaining excellent ion conduction. First-cycle coulombic efficiency data further support this analysis; Comparative Example 4's 81.5% is significantly lower than Example 1's 87.8%, indicating greater irreversible lithium loss during the first charge-discharge cycle.

[0180] Comparative Example 5 used pure PEO as the polymer matrix, although its ionic conductivity (8.95 × 10⁻⁶) was relatively low. -4 While the S / cm ratio remained at an acceptable level, the sharp decline in mechanical properties severely limited its practicality. The Young's modulus was only 105 MPa, less than 40% of that of Example 1 (285 MPa). This insufficient mechanical strength directly affected the processability and reliability of the solid electrolyte membrane. More importantly, the tendency of pure PEO to crystallize at room temperature leads to a decrease in ionic conductivity over time, as reflected in long-term cycling data. Comparative Example 5 showed a capacity retention of 80.8% after 500 cycles, approximately 6 percentage points lower than Example 1.

[0181] The design of the PEO-PPO-PEO triblock copolymer cleverly resolves the contradiction between ion conductivity and mechanical properties. The PEO segment provides Li + Coordination and conduction functions ensure basic ion conduction capabilities; the PPO segment, as a hard segment, provides mechanical support, and its presence disrupts the regular crystal structure of PEO, increasing the proportion of amorphous regions, which is actually beneficial for ion conduction. The data from Examples 8 and 9 in the table further verify the optimization space of the block ratio. When the PEO:PPO ratio is 70:30 (Example 1), the various properties reach the optimal balance.

[0182] The parameter optimization experiments in the table demonstrate the robustness and industrialization potential of the technology in the embodiments of this application. The magnetic composite filler content ranges from 20wt% to 50wt%, and the ionic conductivity ranges from 7.55 × 10⁻⁶. -4 Up to 1.58×10 -3The S / cm ratio exhibited a regular variation, while the cycle performance consistently remained above 83.5%, indicating that the process has a wide tolerance range for filler content. The change in magnetic field strength from 0.2T to 0.5T resulted in an approximately 70% increase in conductivity, but even at the lower magnetic field of 0.2T, the performance was still significantly better than the control without a magnetic field, which makes it possible to reduce equipment costs. The pulse duty cycle had a relatively small impact on performance within the range of 30% to 70%, with an optimal value around 50%, but this was not a stringent requirement, which is beneficial for industrial parameter control.

[0183] Of particular note are the results of multi-parameter synergistic optimization in Example 10. By increasing the content of the magnetic composite filler to 40 wt%, optimizing the magnetic field strength to 0.4 T, adjusting the duty cycle to 55%, and fine-tuning the PEO:PPO ratio to 75:25, the room temperature conductivity was further improved to 1.60 × 10⁻⁶. -3 The S / cm ratio is improved by 25% compared to the baseline embodiment 1, the capacity retention rate after 500 cycles reaches 88.0%, and the storage capacity recovery rate at 60°C is as high as 96.2%. These data not only demonstrate the synergistic effect among the various process parameters, but also show that there is room for further optimization and improvement in the coordination of the various parameters in this embodiment.

[0184] Based on all test data, the manufacturing method of the secondary battery provided in this application, which employs a magnetic field-induced directional alignment of a solid electrolyte membrane, exhibits comprehensive performance advantages. In terms of ion conduction, the room temperature conductivity reaches 10⁻⁶. -3 The S / cm ratio is on the order of 1, achieving a 5-7 times improvement over traditional composite electrolytes, while maintaining excellent performance over a wide temperature range of -10℃ to 60℃. Regarding electrochemical stability, the 5.2V electrochemical window meets the requirements of high-voltage cathode materials, with interface stability exceeding 500 hours, effectively suppressing lithium dendrite growth. In terms of mechanical properties, the 285MPa Young's modulus ensures the structural integrity and ease of processing of the solid electrolyte membrane. As for battery performance, the 87.8% first-cycle coulombic efficiency, 86.5% capacity retention after 500 cycles, and 71.5% 3C rate performance fully meet the requirements for practical application.

[0185] More importantly, through systematic comparative experiments, the embodiments of this application clearly demonstrate that the three-layer core-shell structure and the pulsed magnetic field induce a synergistic effect of "1+1>2". This multi-level, multi-scale synergistic design concept not only solves the key problems faced by traditional composite solid electrolytes, such as tortuous ion conduction, high interfacial impedance, and poor mechanical properties, but also provides a feasible technical path for the commercial application of solid-state batteries. With the rapid development of the electric vehicle and energy storage markets, the technology of the embodiments of this application is expected to play an important role in promoting the industrialization of all-solid-state batteries.

[0186] Those skilled in the art will understand that the above embodiments are specific examples of implementing this application, and in practical applications, various changes in form and detail can be made without departing from the spirit and scope of this application. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this application; therefore, the scope of protection of this application should be determined by the scope defined in the claims.

Claims

1. A method for manufacturing a secondary battery, characterized in that, include: The preparation steps for a solid electrolyte membrane include: A magnetic composite filler is prepared, comprising an ion conductor core, the surface of which is sequentially coated with a magnetic functional layer and a protective layer, wherein the material of the magnetic functional layer comprises a magnetic material and the material of the protective layer comprises an oxide. A polymerization precursor is prepared, the polymerization precursor comprising the magnetic composite filler, polymer matrix, initiator, lithium salt and solvent; The polymer precursor is coated into a film under a pulsed magnetic field so that the magnetic composite filler is oriented along the film thickness direction; The polymerization precursor is initiated to undergo a polymerization reaction, so that the polymerization precursor is solidified into the solid electrolyte membrane. A positive electrode and a negative electrode are provided. The positive electrode, the solid electrolyte membrane, and the negative electrode are wound or stacked and then placed into a housing to form an initial battery cell. The solid electrolyte membrane is located between the positive electrode and the negative electrode.

2. The method for manufacturing a secondary battery according to claim 1, characterized in that, The pulsed magnetic field has a magnetic field strength of 0.2T~0.5T, a frequency of 0.1Hz~10Hz, a duty cycle of 40%~60%, and an action time of 30s~10min.

3. The method for manufacturing a secondary battery according to claim 1, characterized in that, The magnetic functional layer is formed using a chemical co-precipitation method, and the preparation steps include: The ionic conductor nucleus is dispersed in a Fe-containing environment. 2+ and Fe 3+ In aqueous solution; Under the protection of an inert gas, an alkaline precipitant is added to adjust the pH value to 8-12; The reaction is carried out at 20℃~100℃ for 0.5h~12h; After the reaction is complete, anneal at 200℃~600℃ for 0.5h~6h.

4. The method for manufacturing a secondary battery according to claim 1, characterized in that, The protective layer is formed using the sol-gel method, and the preparation steps include: The ion conductor core having the magnetic functional layer is dispersed in an alcohol solvent; A silicon source precursor is added, and a hydrolysis-condensation reaction is carried out using an alkaline or acidic catalyst at 20℃~80℃ for 1h~24h.

5. The method for manufacturing a secondary battery according to claim 1, characterized in that, The polymer precursor has a viscosity of 100 mPa·s to 50000 mPa·s at 25°C and a solid content of 20 wt% to 80 wt%.

6. The method for manufacturing a secondary battery according to claim 1, characterized in that, The number-average molecular weight of the polymer matrix ranges from 1000 g / mol to 100000 g / mol.

7. The method for manufacturing a secondary battery according to claim 1 or 6, characterized in that, The polymer matrix is ​​selected from polyether polymers, polyester polymers, polycarbonate polymers, polynitrile polymers, polysiloxane polymers, polyphosphononitrile polymers, or copolymers thereof.

8. The method for manufacturing a secondary battery according to claim 7, characterized in that, The polymer matrix includes ether oxygen units, and the molar ratio of lithium ions in the lithium salt to ether oxygen units in the polymer matrix is ​​0.01:1 to 0.2:

1.

9. The method for manufacturing a secondary battery according to claim 1, characterized in that, In the polymerization precursor, the amount of the initiator is 0.05wt% to 10wt% of the polymer matrix mass.

10. The method for manufacturing a secondary battery according to claim 1, characterized in that, The polymerization precursor also includes a crosslinking agent, and the amount of the crosslinking agent is 0.1wt% to 20wt% of the polymer matrix mass.

11. A secondary battery, characterized in that, include: A housing, wherein the housing comprises a positive electrode, a solid electrolyte, and a bare cell formed by winding or stacking a negative electrode; The solid electrolyte comprises a magnetic composite filler, a lithium salt, and an electrolyte matrix. The magnetic composite filler is oriented in the electrolyte matrix along the direction from the positive electrode to the negative electrode. The magnetic composite filler includes an ion conductor core, the surface of which is sequentially coated with a magnetic functional layer and a protective layer. The magnetic functional layer is made of a magnetic material, and the protective layer is made of an oxide. The lithium salt is dispersed in the electrolyte matrix. The electrolyte matrix is ​​formed by the polymerization reaction of a polymer matrix and an initiator.

12. The secondary battery according to claim 11, characterized in that, The particle size of the ion conductor core is 200nm~1000nm; the thickness of the magnetic functional layer is 10nm~200nm; and the thickness of the protective layer is 1nm~50nm.

13. The secondary battery according to claim 12, characterized in that, The total particle size range of the magnetic composite filler is 300nm~1500nm.

14. The secondary battery according to claim 11, characterized in that, The porosity of the protective layer is 5% to 50%.

15. The secondary battery according to claim 11, characterized in that, The mass of the magnetic functional layer accounts for 3wt% to 40wt% of the mass of the magnetic composite filler.

16. The secondary battery according to claim 11, characterized in that, The saturation magnetization of the magnetic composite filler is 5 Am. 2 / kg~50Am 2 / kg.

17. A battery device, characterized in that, The battery device includes a secondary battery manufactured by the method of manufacturing a secondary battery as described in any one of claims 1 to 10, or a secondary battery as described in any one of claims 11 to 16, wherein the battery device includes one or more of a battery module, a battery pack, and an energy storage battery.

18. An energy storage device, characterized in that, Includes the battery device as described in claim 17, wherein the battery device is used to store electrical energy.

19. An electrical appliance, characterized in that, Includes the battery device as described in claim 17, the battery device being used to provide electrical energy.

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