Solid electrolyte, pole piece, diaphragm, and corresponding preparation methods and battery thereof

Abstract

The invention belongs to the technical field of lithium ion batteries, and discloses a solid electrolyte, a pole piece, a diaphragm, a corresponding preparation method and a battery, and the preparation method of the solid electrolyte comprises the following steps: mixing a nano magnetic material with a lithium ion solid electrolyte precursor liquid to obtain a first mixed solution; mixing one-dimensional conductive carbon fibers with the first mixed solution to obtain a second mixed solution; and sintering the second mixed solution to obtain the solid electrolyte. A one-dimensional fiber (solid electrolyte) structure coated with a nano magnetic material-solid electrolyte composite layer is formed by taking one-dimensional conductive carbon fibers as a framework, high ion and electron conductivity is achieved, magnetic response characteristics are given to nano magnetic materials, and the lithium ion transmission distance can be shortened through directional arrangement. The method solves the problems of zigzag and dispersed ion transmission path and insufficient electron conduction of the traditional solid electrolyte, and the prepared solid electrolyte is suitable for a high-energy-density and ultrafast rechargeable battery system.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery technology, and in particular to a solid electrolyte, electrode, separator, and corresponding preparation methods and batteries. Background Technology

[0002] With the rapid development of the new energy industry, high-end equipment such as electric vehicles and electric aircraft are placing higher demands on the performance of rechargeable batteries, especially the increasingly urgent need for the synergistic combination of "high energy density" and "ultra-fast charging capability." Currently, the charging rate of lithium-ion batteries has gradually upgraded from the traditional 2C to 4C, 6C, and even 8C. However, in the process of increasing the rate, the technical bottleneck caused by ultra-thick or high-density cathode sheets has remained difficult to overcome, becoming the core issue restricting the overall performance of batteries.

[0003] In existing technologies, to improve battery energy density, the active material loading is typically increased by increasing the thickness of the positive electrode or increasing the electrode compaction density. However, both of these methods have significant negative impacts on lithium-ion transport and electrolyte wetting: on the one hand, ultra-thick electrodes significantly increase the transport distance of lithium ions between active material particles, while high compaction density reduces electrode porosity, resulting in a tortuous lithium-ion diffusion path and a sharp increase in diffusion resistance, directly limiting the increase in charging rate; on the other hand, low-porosity high-compaction electrodes make it difficult to achieve rapid and uniform electrolyte penetration, easily forming "localized dry areas." During high-rate charging, insufficient lithium-ion supply in these areas can lead to lithium deposition on the negative electrode surface, which not only reduces battery cycle stability but also poses safety hazards. Summary of the Invention

[0004] The main objective of this invention is to provide a solid electrolyte, a composite cathode sheet, a corresponding preparation method, and a semi-solid battery, aiming to solve the technical problems of large lithium-ion transport distance, high ion diffusion resistance, and poor wetting caused by thickness and high compaction density in existing lithium batteries.

[0005] To achieve the above-mentioned objective, the first aspect of this invention provides a method for preparing a solid electrolyte, the method comprising: The nano-magnetic material was mixed with the lithium-ion solid electrolyte precursor liquid to obtain the first mixed solution; One-dimensional conductive carbon fiber is mixed with the first mixed solution to obtain a second mixed solution; The second mixed solution is sintered to obtain the solid electrolyte.

[0006] Further, the mixing of the nanomagnetic material with the lithium-ion solid electrolyte precursor liquid to obtain a first mixed solution includes: The nanomagnetic material was ball-milled and mixed with the lithium-ion solid electrolyte precursor liquid to obtain the first mixed solution.

[0007] Further, the step of mixing the one-dimensional conductive carbon fiber with the first mixed solution to obtain a second mixed solution includes: The one-dimensional conductive carbon fiber placed in a template of a preset material is placed into the first mixed solution to obtain the second mixed solution.

[0008] Furthermore, the preset material is one or more combinations of polyethylene oxide, polyvinyl alcohol, polyvinyl butyral, paraffin wax, or epoxy resin; the sintering temperature is 600-1050℃.

[0009] Furthermore, the nanomagnetic material is one or more of Fe3O4 nanoparticles, nickel (Ni) nanoparticles, and Au-Fe3O4 nanomaterials composed of Fe3O4 and gold (Au), and the mass ratio of the nanomagnetic material to the lithium-ion solid electrolyte precursor material in the lithium-ion solid electrolyte precursor liquid is 0.1~3:100.

[0010] Furthermore, the lithium-ion solid electrolyte precursor fluid is one or more combinations of LATP, LAGP, LLZO, LLTO, or LLZTO.

[0011] A second aspect of the present invention provides a solid electrolyte, wherein the solid electrolyte is prepared according to the preparation method of any one of the preceding claims.

[0012] Furthermore, the solid electrolyte is a solid electrolyte with the one-dimensional conductive carbon fiber as the skeleton and the surface coated with a Fe3O4-solid electrolyte composite layer.

[0013] A third aspect of this invention provides a method for preparing a composite positive electrode, comprising: The positive electrode powder, conductive agent, binder and the above solid electrolyte are mixed to obtain the positive electrode coating material; The positive electrode coating material is coated onto the positive electrode current collector; The current collector coated with the positive electrode coating material is placed in a preset magnetic field for drying to obtain the composite positive electrode sheet.

[0014] The fourth aspect of this invention provides a composite positive electrode sheet, wherein the composite positive electrode sheet is prepared by the above-described method for preparing a composite positive electrode sheet.

[0015] The fifth aspect of this invention discloses a method for preparing a composite negative electrode, comprising: Thickener, negative electrode powder, conductive agent, binder and the above solid electrolyte are mixed to obtain negative electrode coating material; The negative electrode coating material is coated onto the negative electrode current collector; The negative electrode current collector coated with the coating material is placed in a preset magnetic field for drying to obtain the composite negative electrode sheet.

[0016] The sixth aspect of this invention provides a composite negative electrode sheet, which is prepared by the above-described method for preparing a composite negative electrode sheet.

[0017] The seventh aspect of this invention discloses a method for preparing a composite diaphragm, comprising: The binder and the above-mentioned solid electrolyte are mixed to obtain the membrane coating material; The diaphragm coating material is coated onto the base film; The base film coated with the diaphragm coating material is placed in a preset magnetic field and dried to obtain the composite diaphragm.

[0018] A seventh aspect of the present invention provides a composite membrane, wherein the composite membrane is prepared according to the above-described method for preparing a composite membrane.

[0019] An eighth aspect of the present invention provides a semi-solid-state battery, comprising: a positive electrode, a negative electrode, a separator spaced between the positive and negative electrode, and an electrolyte, wherein the positive electrode is the aforementioned composite positive electrode; and / or, The negative electrode is the aforementioned composite negative electrode; and / or, The diaphragm is the composite diaphragm described above.

[0020] Beneficial effects: This application provides solid electrolytes, electrodes (composite positive electrodes and composite negative electrodes), separators, and their corresponding preparation methods and batteries. Through a full-chain innovation of "one-dimensional solid electrolyte design - directional preparation of composite electrodes - semi-solid battery integration," it achieves multi-dimensional performance breakthroughs. Firstly, it overcomes the bottleneck of ion transport: the fiber (solid electrolyte) formed by the composite of one-dimensional conductive carbon fiber and nano-magnetic material-solid electrolyte is arranged perpendicular to the current collector under a magnetic field, which shortens the lithium-ion transport distance in ultra-thick electrodes and reduces the internal resistance of ion diffusion under 5C-8C ultra-fast charging. For example, the capacity retention rate reaches more than 85% after 1000 cycles of 5C fast charging. Furthermore, after coating the solid electrolyte onto the positive electrode, negative electrode, or separator, composite positive electrode, composite negative electrode, and composite separator are obtained, all of which can reduce the lithium-ion transport distance and reduce the internal resistance of ion diffusion.

[0021] Secondly, it achieves synergy between high energy density and fast charging: the compaction density of ultra-thick electrode sheets is improved, with an energy density of 310~400Wh / kg, while supporting fast charging above 5C, solving the industry problems of "poor wetting of high-pressure compacted electrode sheets" and "sacrifice of rate capability for thick electrode sheets".

[0022] Third, enhanced cycling and safety performance: The fibrous solid electrolyte has a tight interface and stable directional channels, with a capacity retention rate of >85% (up to 92%) after 1000 cycles; the semi-solid system reduces the amount of electrolyte used, reduces the risk of thermal runaway, and has both long life and high safety.

[0023] In summary, this application achieves synergistic optimization in "ultra-fast charging, high energy density, long cycle life, and high safety", providing a leading-edge battery solution for electric vehicles, electric aircraft, and other fields. Attached Figure Description

[0024] Figure 1 This is a schematic flowchart of a method for preparing a solid electrolyte according to an embodiment of the invention; Figure 2 A schematic flowchart illustrating a method for preparing a composite positive electrode according to an embodiment of the invention; Figure 3 A schematic flowchart illustrating a method for preparing a composite negative electrode sheet according to an embodiment of the invention; Figure 4 This is a schematic flowchart illustrating a method for preparing a composite diaphragm according to an embodiment of the invention.

[0025] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0027] Those skilled in the art will understand that, unless specifically stated otherwise, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the term “comprising” as used in this specification means the presence of features, integers, steps, operations, elements, modules, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, modules, components, and / or groups thereof. It should be understood that when we say an element is “connected” or “coupled” to another element, it can be directly connected or coupled to the other element, or there may be intermediate elements. Furthermore, “connected” or “coupled” as used herein can include wireless connections or wireless coupling. The term “and / or” as used herein includes all or any modules and all combinations of one or more associated listed items.

[0028] It will be understood by those skilled in the art that, unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and should not be interpreted in an idealized or overly formal sense unless specifically defined as herein.

[0029] Reference Figure 1 This invention provides a method for preparing a solid electrolyte, the method comprising: S11: Mix the nanomagnetic material with the lithium-ion solid electrolyte precursor liquid to obtain the first mixed solution.

[0030] The aforementioned nanomagnetic materials can be one or more combinations of Fe3O4 nanoparticles, nickel (Ni) nanoparticles, and Au-Fe3O4 nanomaterials composed of Fe3O4 and gold (Au). Taking nano-Fe3O4 as an example, it refers to iron(III) oxide particles with a particle size of 50-200 nm, which have strong magnetic response characteristics and can be oriented under the influence of an electromagnetic field. The lithium-ion solid electrolyte precursor liquid refers to a liquid mixture containing elements required for the formation of lithium-ion solid electrolytes (such as Li, Al, Ti, P, etc.), which can be converted into a solid electrolyte with ion conduction capabilities after sintering. In this step, the nanomagnetic materials are uniformly dispersed in the precursor liquid through mixing, laying the foundation for the subsequent formation of a composite layer with both magnetic response and ion conduction functions. For example, 0.2 g of nano-Fe3O4 is added to 100 g of LATP solid electrolyte precursor liquid and stirred for 30 min to obtain the first mixed solution. This achieves the initial dispersion of nano-Fe3O4 and the precursor, avoiding uneven magnetic response caused by Fe3O4 agglomeration.

[0031] S12: Mix one-dimensional conductive carbon fiber with the first mixed solution to obtain a second mixed solution.

[0032] One-dimensional conductive carbon fibers generally refer to carbon fibers with a length of 50-200 μm and a diameter of 5-20 μm, possessing excellent electronic conductivity (conductivity > 1000 S / m) and a one-dimensional linear structure. This step involves uniformly loading the first mixed solution onto the surface of the one-dimensional conductive carbon fibers, forming a preliminary composite structure of "carbon fiber-precursor-Fe3O4". In a specific example, 5 g of one-dimensional conductive carbon fibers (100 μm in length and 10 μm in diameter) are added to the aforementioned first mixed solution and ultrasonically treated for 30 min, allowing the mixed solution to be uniformly adsorbed onto the carbon fiber surface, resulting in a second mixed solution. Utilizing the one-dimensional structure of the carbon fibers as a framework ensures the formation of linear transport channels for the subsequent solid electrolyte, while the carbon fibers provide an electronic conduction path, solving the problem of electronic insulation in the solid electrolyte.

[0033] S13: Sinter the second mixed solution to obtain the solid electrolyte.

[0034] Sintering refers to the process of chemically reacting, crystallizing, and solidifying a precursor through high-temperature treatment to form a solid electrolyte with a stable structure and ion conductivity. During sintering, the solvent in the precursor liquid evaporates, and the solute decomposes and recombines, ultimately forming a composite layer of nanomagnetic materials and lithium-ion solid electrolyte on the carbon fiber surface. In a specific example, a second mixed solution is placed in a ceramic crucible and sintered in a muffle furnace at 800℃ for 8 hours (heating rate 5℃ / min). After natural cooling, a one-dimensional solid electrolyte with a diameter of 15-25 μm and a length of 80-180 μm is obtained. High-temperature sintering enables the solid electrolyte to form a stable crystal structure, ensuring high ion conductivity (>10). -4 (S / cm), while the nano-magnetic material is uniformly distributed in the composite layer, preserving the magnetic response characteristics.

[0035] This embodiment utilizes a three-step process of "mixing-loading-sintering" to prepare a solid electrolyte with a one-dimensional conductive carbon fiber skeleton and a surface-coated nano-magnetic material-solid electrolyte composite layer. Unlike existing technologies that simply mix solid electrolyte particles with conductive agents, this method leverages the structural guidance of the one-dimensional carbon fiber to create continuous linear ion transport channels in the solid electrolyte. Simultaneously, the introduction of Fe3O4 provides a foundation for subsequent directional alignment, solving the problems of dispersed ion conduction paths and insufficient electron conduction in traditional solid electrolytes. Specifically, the solid electrolyte formed in this embodiment possesses both ion conduction (solid electrolyte layer) and electron conduction (carbon fiber) capabilities, reducing the internal resistance of the electrode; the one-dimensional structure shortens the lithium-ion transport distance, adapting to ultra-fast charging requirements; and the magnetic response characteristics of the nano-magnetic material enable subsequent directional alignment in the positive electrode, negative electrode, and separator, further optimizing ion transport efficiency.

[0036] In one embodiment, the above-mentioned mixing of the nanomagnetic material with the lithium-ion solid electrolyte precursor liquid to obtain a first mixed solution includes: S111: The nanomagnetic material is ball-milled and mixed with the lithium-ion solid electrolyte precursor liquid to obtain the first mixed solution.

[0037] Ball milling is a process that uses grinding balls to impact and grind materials in a rotating container to achieve uniform dispersion of a solid-liquid system. Compared to ordinary stirring, it can more effectively break up the agglomeration of nanoparticles. This step ensures that the nanomagnetic material is completely dispersed in the precursor liquid by controlling the ball milling rate and time, avoiding agglomerates from affecting the uniformity of subsequent magnetic response and ion conduction. In a specific example, the same raw materials as in the above examples (0.2g nano Fe3O4 + 100g LATP precursor liquid) were used, with the addition of zirconia balls (ball-to-material ratio 5:1), and ball milling was performed in a planetary ball mill at a rate of 600 r / min for 5 h to obtain a first mixed solution (the nano Fe3O4 agglomerate particle size was <500nm as measured by a laser particle size analyzer). The mechanical force generated by ball milling effectively disperses the nano Fe3O4 agglomerates, making their one-dimensional size distribution more uniform and ensuring the consistency of the magnetic response of nano Fe3O4 in the subsequent composite layer.

[0038] This embodiment optimizes "simple stirring and mixing" to "ball milling and mixing," solving the agglomeration problem of nano-magnetic materials by controlling ball milling parameters (speed 400-800 r / min, time 4-6 h). In existing technologies, if only stirring is used, nano-magnetic materials are prone to agglomeration due to their high surface energy (agglomerate particle size is often >2 μm), leading to uneven magnetic response in the subsequent composite layer. However, this method ensures monodispersity of the nano-magnetic materials through ball milling, providing a uniform magnetic driving force for directional alignment. Specifically, ball milling and mixing improves the dispersion uniformity of the nano-magnetic materials and enhances the consistency of magnetic response; the components in the precursor liquid are mixed more thoroughly, resulting in increased density of the solid electrolyte layer formed by subsequent sintering; and the ionic conductivity is improved compared to stirring and mixing.

[0039] In one embodiment, the process of mixing one-dimensional conductive carbon fiber with the first mixed solution to obtain a second mixed solution includes: S121: The one-dimensional conductive carbon fiber placed in the template of the preset material is placed into the first mixed solution to obtain the second mixed solution.

[0040] The template for the aforementioned pre-designed material is a carrier made of a specific material (such as a polymer) used to fix the morphology of one-dimensional conductive carbon fibers. It maintains the one-dimensional arrangement of the carbon fibers and facilitates handling. This step uses the template to fix the one-dimensional structure of the carbon fibers, preventing entanglement and agglomeration during mixing and ensuring that the precursor is uniformly loaded onto the surface of each individual carbon fiber. In a specific example, the one-dimensional conductive carbon fiber (5g) from the above embodiment is embedded in a template (50μm thick, containing parallel fiber channels) to form a "carbon fiber-template" composite. This composite is then immersed in a first mixing solution and allowed to stand for 2 hours, allowing the solution to penetrate the template through capillary action and uniformly coat the carbon fibers, resulting in a second mixing solution. The template restricts the disordered movement of the carbon fibers, avoiding uneven precursor loading caused by entanglement, thus greatly improving the integrity of the one-dimensional structure of the subsequent solid electrolyte.

[0041] In this embodiment, a "pre-set material template" is introduced to assist in the mixing of carbon fibers and precursors, solving the process challenge of easy polymerization of one-dimensional carbon fibers due to their fineness. In existing technologies, direct mixing of carbon fibers easily forms "fiber bundles," resulting in the precursor not uniformly coating individual fibers. This method, however, uses a template to fix the parallel arrangement of carbon fibers, ensuring a uniform precursor layer load on the surface of each fiber, laying the foundation for the subsequent formation of a regular one-dimensional solid electrolyte. Specifically, the dispersion of carbon fibers is improved, avoiding entanglement and polymerization, and the uniformity of precursor loading is greatly improved. The template-assisted operation simplifies the process, and the dimensional consistency (length and diameter deviation) of the batch-prepared solid electrolyte is controlled within ±5%. After subsequent sintering, the ion conduction uniformity of the solid electrolyte is improved, and the fluctuation of electrode internal resistance is reduced.

[0042] In one embodiment, the aforementioned preset material is one or more combinations of polyethylene oxide (PEO), polyvinyl alcohol, polyvinyl butyral, paraffin wax, or epoxy resin; the sintering temperature is 600-1050℃.

[0043] The aforementioned polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), paraffin wax, and epoxy resin are all organic polymer materials with processability and thermal decomposition volatility. Specifically: Polyethylene oxide (PEO): decomposition temperature approximately 200-300℃, complete decomposition and volatilization above 300℃. Polyvinyl alcohol (PVA): decomposition temperature approximately 250-350℃, gradual complete volatilization above 350℃. Polyvinyl butyral (PVB): decomposition temperature approximately 280-400℃, complete decomposition and volatilization above 400℃. Paraffin wax: volatilization / decomposition temperature approximately 150-280℃, complete volatilization above 280℃ (no residue). Epoxy resin: decomposition temperature approximately 300-450℃, complete decomposition above 450℃ (crosslinking structures require higher temperatures). One or more combinations of polyethylene oxide, polyvinyl alcohol, polyvinyl butyral, paraffin wax, or epoxy resin can be used as template materials to both fix the carbon fiber morphology and completely remove them during subsequent sintering, avoiding the introduction of impurities. In one specific example, PEO particles with a molecular weight of 100,000 were dissolved in water to prepare a 10 wt% polyethylene oxide solution. One-dimensional conductive carbon fibers were uniformly dispersed in the solution, cast into a film (50 μm thick), and dried to form a PEO template (with carbon fibers embedded parallel within it). PEO has good compatibility with ethanol (the precursor liquid solvent), ensuring that the precursor fully wets the carbon fibers. During high-temperature sintering, PEO completely decomposes (decomposition temperature 350-400℃), leaving no residual impurities that affect the performance of the solid electrolyte.

[0044] The sintering temperature is 600-1050℃, and the time is 7-10 hours. Sintering temperature and time are key parameters affecting the degree of crystallization of the solid electrolyte. Too low a temperature leads to incomplete crystallization (low ionic conductivity), while too high a temperature may cause carbon fiber oxidation or solid electrolyte decomposition. This step optimizes the sintering parameters to ensure complete decomposition of the template. In a specific example, the obtained second mixed solution (containing the template) is placed in a muffle furnace, first heated to 400℃ at 2℃ / min (held for 2 hours to remove PEO), then heated to 900℃ at 5℃ / min, sintered for 9 hours, and naturally cooled to obtain the solid electrolyte. Sintering at 900℃ forms a one-dimensional solid electrolyte material from the lithium-ion solid electrolyte precursor.

[0045] This embodiment clarifies the concepts of "PEO template" and "sintering parameters," resolving the issue of matching template material selection with the sintering process. In existing technologies, if a high-temperature resistant template (such as ceramic) is used, it cannot be removed and impurities are introduced; if the sintering parameters are inappropriate, LATP easily forms amorphous or impurity phases (such as...). The ionic conductivity decreases significantly. In this method, the degradability of PEO is matched with the sintering temperature of 600-1050℃, ensuring high purity and stable performance of the final solid electrolyte.

[0046] In one embodiment, the above-mentioned nanomagnetic material is nano-Fe3O4, and the mass ratio of the nano-Fe3O4 to the lithium-ion solid electrolyte precursor material in the lithium-ion solid electrolyte precursor liquid is 0.1~3:100.

[0047] The mass ratio is the ratio of the mass of nano-Fe3O4 to the total mass of the lithium-ion solid electrolyte precursor (such as the high-temperature sintering product of solutes like LiCl and titanium isopropoxide in LATP) in the precursor solution, which affects the balance between magnetic response intensity and ionic conductivity. For example, if the ratio is too low, the magnetic response will be insufficient and unable to drive fiber orientation; if it is too high, nano-Fe3O4 will occupy too much volume, hindering lithium-ion transport. In a specific example, 100g of LATP precursor material (14.38g of lithium chloride LiCl + 20.8g of titanium dioxide TiO2 + 10.5g of aluminum chloride AlCl3 + 108g of isopropyl dihydrogen phosphate C3H9O4P dissolved in 1000g of anhydrous ethanol solution, sintered to obtain 100g of LATP precursor material) was used, and nano-Fe3O4 (0.1g, 1.5g, and 3g) was added at ratios of 0.1:100, 1.5:100, and 3:100, respectively.

[0048] This embodiment limits the mass ratio range of nano-Fe3O4 to the precursor material, resolving the contradiction between "magnetic response requirements" and "ionic conductivity requirements." In existing technologies, if the ratio is not controlled, an excess of nano-Fe3O4 will lead to the formation of an "insulating region" in the solid electrolyte layer (Fe3O4 has no ionic conductivity), resulting in a decrease in ionic conductivity; an insufficient ratio will prevent effective orientation in an electromagnetic field. This method ensures synergistic function between the two by using a mass ratio range of 0.1 to 3:100 between nano-Fe3O4 and the lithium-ion solid electrolyte precursor material in the lithium-ion solid electrolyte precursor liquid.

[0049] In one embodiment, the lithium-ion solid electrolyte precursor fluid is one or more combinations of LATP, LAGP, LLZO, LLTO, or LLZTO.

[0050] LATP: Lithium titanium aluminum phosphate; LAGP: Lithium aluminum germanium phosphate, a germanium-substituted derivative of LATP; LLZO: Garnet-type lithium lanthanum zirconium oxide solid electrolyte; LLTO: Lithium lanthanum titanate, a perovskite solid electrolyte; LLZTO: Tantalum-doped garnet-type lithium lanthanum zirconium oxide, a derivative of LLZO.

[0051] Different precursor fluids correspond to different types of solid electrolytes, which can be selected according to battery requirements (such as voltage and stability). This embodiment verifies its compatibility with the process.

[0052] This embodiment expands the types of precursor liquids for lithium-ion solid electrolytes, demonstrating the universality of this method. In the prior art, the preparation processes for different types of solid electrolytes vary greatly (e.g., LLZO requires a higher sintering temperature). This method, by adjusting sintering parameters (e.g., 1000℃ for LLZO), allows various precursor liquids to be adapted to the "mixing-loading-sintering" process, forming a one-dimensional solid electrolyte that combines magnetic response and ion conduction, thus solving the dependence of traditional processes on specific electrolytes.

[0053] This application also provides a solid electrolyte, which is prepared according to the solid electrolyte preparation method described in any of the above embodiments.

[0054] The solid electrolyte is a one-dimensional fibrous structure with a core of one-dimensional conductive carbon fiber and a surface coating consisting of nano-magnetic material particles and solid electrolyte crystals. In other words, the solid electrolyte is a solid electrolyte with the one-dimensional conductive carbon fiber as its framework and a surface coated with a nano-magnetic material-solid electrolyte composite layer.

[0055] The solid electrolyte of this embodiment is a direct product prepared by the solid electrolyte preparation method described in any of the above embodiments. Its core innovation lies in its "one-dimensional fibrous structure" and "composite layer structure." In the prior art, solid electrolytes are mostly particulate, requiring mixing with conductive agents and easily forming interfacial impedance. This solid electrolyte, however, uses carbon fibers as electron channels and the composite layer as ion channels, and its one-dimensional structure can be oriented, structurally solving the problems of "ion-electron conduction separation" and "long transport paths." It possesses both high ionic conductivity and electronic conductivity; the one-dimensional fibrous structure can be oriented within the positive electrode, shortening the lithium-ion transport distance; and the composite layer and carbon fiber interface are tightly bonded, resulting in high structural stability during cycling.

[0056] Reference Figure 2 This application also provides a method for preparing a composite positive electrode, comprising: S21: Mix the positive electrode powder, conductive agent, binder and solid electrolyte to obtain the positive electrode coating material.

[0057] The cathode powder, such as NCM811, is a high-capacity ternary cathode material; conductive agents, such as carbon black (SuperP), assist in electron conduction; and binders, such as PVDF (polyvinylidene fluoride), bind the components together to form a film. They are mixed in a specific ratio to ensure uniform dispersion of the solid electrolyte in the cathode material, while balancing electron conduction and structural strength. In a specific example, 95.5g of NCM811, 1.5g of carbon black, 2g of PVDF, and 1g of solid electrolyte are added to N-methylpyrrolidone (NMP) to form a slurry, which is stirred for 2 hours to obtain the cathode coating material. A low proportion of solid electrolyte can form effective ion channels, avoiding the energy density decrease caused by excessive addition.

[0058] S22: Apply the positive electrode coating material onto the positive electrode current collector.

[0059] The positive electrode current collector, such as aluminum foil, is used to collect electrons and support the coating. The positive electrode coating material is uniformly coated onto the surface of the aluminum foil, with the thickness controlled to achieve high energy density. In one specific example, a doctor blade coating method is used to coat the positive electrode slurry onto the aluminum foil.

[0060] S23: The positive current collector coated with the positive electrode coating material is placed in a preset magnetic field for drying to obtain the composite positive electrode sheet.

[0061] A preset magnetic field refers to a magnetic field whose strength can be controlled artificially, such as an electromagnetic field with a strength of 10T, which can drive the solid electrolyte containing nano-magnetic materials to align in a specific direction. During the drying process, the magnetic field causes the solid electrolyte to align along the direction of the magnetic field (perpendicular to the current collector), forming vertical ion channels. In a specific example, a pre-dried positive electrode current collector coated with the aforementioned positive electrode coating material is placed in a uniform magnetic field of 10T and dried at 120°C for 2 hours (to remove residual NMP), resulting in a composite positive electrode sheet (solid electrolyte vertical orientation >80%, as observed by SEM (Scanning Electron Microscope) cross-section). Vertical alignment shortens the transport distance of lithium ions from the current collector to the electrode surface.

[0062] The core of the composite cathode fabrication method in this embodiment lies in the "magnetic field-assisted orientation" process, which solves the problem of long lithium-ion transport distance in ultra-thick electrodes. In the prior art, lithium ions in ultra-thick electrodes need to diffuse in a circuitous manner along a direction parallel to the current collector, with a diffusion distance of hundreds of micrometers; while this method drives the solid electrolyte to align vertically through a magnetic field, constructing a "short-path" ion channel, while retaining the advantage of high energy density.

[0063] In one embodiment, this application also provides a composite positive electrode sheet, which is prepared according to the preparation method of the composite positive electrode sheet in the above embodiment.

[0064] The composite positive electrode sheet consists of an aluminum foil current collector and a 100 μm thick coating. The coating contains vertically oriented one-dimensional solid electrolyte, carbon black, and PVDF distributed among NCM811 particles, with the vertical alignment of the solid electrolyte exceeding 80%. In a specific example, a composite positive electrode sheet was prepared using the method described in the above embodiment. Testing revealed the following compaction density: (Traditional film approx.) ); Area capacity: (The capacity of a traditional 50μm electrode is approximately...) Ion diffusion resistance: 80mΩ (compared to approximately 200mΩ for a traditional 100μm electrode). Maintaining low ion diffusion resistance despite high areal capacity (high energy density) lays the foundation for ultra-fast charging.

[0065] The composite cathode sheet of this embodiment is a product obtained by the preparation method of the composite cathode sheet in the above embodiments. Its core innovation lies in the synergy of "high thickness + vertical ion channel". In the prior art, ultra-thick electrodes cannot achieve high-rate charging due to high diffusion resistance; however, this composite cathode sheet, through the vertical orientation of the solid electrolyte, reduces diffusion resistance while increasing thickness, thus overcoming the contradiction between "high energy density and high rate".

[0066] Reference Figure 3 This application also provides a method for preparing a composite negative electrode, comprising: S31: Thickener, negative electrode powder, conductive agent, binder and solid electrolyte are mixed to obtain negative electrode coating material; S32: Apply the negative electrode coating material onto the negative electrode current collector; S33: The negative electrode current collector coated with the coating material is placed in a preset magnetic field for drying to obtain the composite negative electrode sheet.

[0067] In this embodiment, by rationally proportioning the components and combining them with magnetic field-assisted drying, high-efficiency compatibility between the solid electrolyte and the negative electrode system is achieved. One or more of sodium carboxymethyl cellulose (CMC) and hydroxypropyl methyl cellulose (HPMC) are selected as thickeners to adjust the viscosity of the negative electrode coating material. The negative electrode main powder is one or more of graphite, silicon-based materials, lithium titanate, or hard carbon, preferably a composite system of silicon-based materials and graphite, balancing capacity and cycle stability. The conductive agent is one or more of acetylene black, Ketjen black, and carbon nanotubes. The binder is one or more of styrene-butadiene rubber (SBR) and polyvinylidene fluoride (PVDF). The amount of the solid electrolyte added is 5%-20% of the mass of the negative electrode main powder to ensure the continuity of the ion conduction path.

[0068] Thickener and deionized water are mixed and stirred until completely dissolved. Then, the negative electrode powder, conductive agent, binder, and solid electrolyte are added sequentially. The mixture is stirred using a planetary mixer at 2000-3000 rpm for 30-60 minutes to obtain a uniformly dispersed negative electrode coating material. The negative electrode coating material is then coated onto a copper foil current collector using a doctor blade, with a coating thickness of 50-200 μm. The coated current collector is placed in a preset magnetic field of 0.1-1 T and dried at 60-120℃ for 1-3 hours. The magnetic field promotes the directional alignment of the nano-magnetic materials in the solid electrolyte, forming ordered ion conduction channels, and simultaneously enhances the adhesion between the coating layer and the current collector.

[0069] In one embodiment, this application also provides a composite negative electrode sheet, which is prepared according to the above-described method for preparing a composite negative electrode sheet.

[0070] The composite negative electrode sheet prepared by the above method has a uniform microstructure and no obvious agglomeration in the coating layer. Using copper foil as the current collector, the solid electrolyte, negative electrode powder, conductive agent, and binder in the coating layer are tightly bonded together. The directional arrangement of the nano-magnetic materials improves ion conduction efficiency, making it suitable for high-energy-density semi-solid-state batteries.

[0071] Reference Figure 4 This application also provides a method for preparing a composite diaphragm, comprising: S41: Mix the binder and the above solid electrolyte to obtain the membrane coating material; S42: Apply the diaphragm coating material onto the base film; S43: The base film coated with the diaphragm coating material is placed in a preset magnetic field for drying to obtain the composite diaphragm.

[0072] In this embodiment, the composite membrane improves ion conductivity and compatibility by coating a base membrane with a solid electrolyte and optimizing its structure through magnetic field-assisted drying. The binder is one or more of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyacrylate, with a mass ratio of 1:5 to 1:10 to the solid electrolyte. The base membrane is a polypropylene (PP), polyethylene (PE), or PP / PE composite porous membrane with a pore size of 0.1-1 μm and a porosity of 30%-50%. The binder is dissolved in solvents such as N-methylpyrrolidone (NMP), acetone, or ethanol, and the solid electrolyte is added. The mixture is ultrasonically dispersed for 30-60 min, followed by mechanical stirring for 20-40 min to obtain a uniform membrane coating material with a solid content controlled at 10%-30%. The diaphragm coating material is coated on one or both sides of the base film using a micro-grooving coating method, with a coating thickness of 1-10 μm. The coated base film is then placed in a preset magnetic field of 0.05-0.5T and dried at 80-150℃ for 2-4 hours. The magnetic field can promote the directional distribution of nano-magnetic materials in the coating, reduce ion conduction resistance, and improve the bonding strength between the coating and the base film.

[0073] This application also provides a composite membrane, which is prepared by the above-described method for preparing composite membranes.

[0074] The composite membrane comprises a base membrane and a composite coating applied to the surface of the base membrane. The composite coating consists of a binder and the aforementioned solid electrolyte. Its ionic conductivity is ≥ (25℃), breakdown voltage ≥100V / μm, air permeability 50-200s / 100mL, low interface impedance with positive and negative electrodes, which can effectively suppress lithium dendrite growth and improve battery safety performance and cycle stability.

[0075] This application also provides a semi-solid-state battery, comprising: a positive electrode, a negative electrode, a separator spaced between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode is the composite positive electrode described above; and / or, the negative electrode is the composite negative electrode described above; and / or, the separator is the composite separator described above.

[0076] The core of this embodiment of the semi-solid-state battery lies in the use of the aforementioned composite positive electrode, composite negative electrode, and / or composite separator, which solves the problem of the traditional semi-solid-state battery's inability to simultaneously achieve high energy density and ultra-fast charging. In the prior art, the electrolyte wettability of semi-solid-state batteries is better than that of all-solid-state batteries, but the ultra-thick positive electrode is still limited by ion diffusion; while this battery accelerates the transport of lithium ions in the electrolyte through the vertical ion channels of the composite positive electrode, making ultra-fast charging above 5C possible, while retaining the high safety of semi-solid-state batteries (small electrolyte volume). In addition, if a composite negative electrode and composite separator are used, the lithium ion transport distance can be shortened, reducing the internal resistance of ion diffusion.

[0077] The following is a comparison between the comparative examples and the embodiments of the semi-solid-state battery of this application: Comparative Examples 1-5: Preparation method: Traditional particulate LATP solid electrolyte (without nanomagnetic materials and carbon fibers) is used to fabricate the positive electrode, negative electrode, and / or separator, and finally assembled into a semi-solid-state battery. The content of particulate LATP solid electrolyte in the positive and negative electrodes, as well as the thickness on the separator, are detailed in Comparative Examples 1-5 in the table below.

[0078] Specific embodiments 1-13 of this application: Nano-Fe3O4 was ball-milled and mixed with LATP solid electrolyte precursor liquid, which contained lithium chloride (LiCl) and titanium isopropoxide (C). 12 H 28 The Fe3O4-LATP precursor solution was composed of TiO4, aluminum chloride (AlCl3), dihydroisopropyl phosphate (C3H9PO4), and ethanol. The mass ratio of nano Fe3O4 to LATP precursor material was 0.5:100. The ball milling rate was 600 r / min, and the ball milling was carried out for 6 h to obtain a uniformly dispersed Fe3O4-LATP precursor solution. A PEO template containing one-dimensional conductive carbon fibers was immersed in Fe3O4-LATP precursor solution, and the PEO template was removed by sintering to obtain a solid electrolyte. The sintering temperature was 700℃ and the sintering time was 10 h. The aforementioned solid electrolyte is used to fabricate composite positive electrode sheets, composite negative electrode sheets, and / or composite separators, and is ultimately assembled into a semi-solid-state battery. During the fabrication of the composite positive electrode sheets, composite negative electrode sheets, and / or composite separators, drying is performed under the influence of an electromagnetic field with a magnetic field strength of 10T, so that the one-dimensional solid electrolytes are vertically and uniformly arranged on the positive electrode current collector, negative electrode current collector, and base membrane. The content of the one-dimensional solid electrolytes in the composite positive electrode sheets and composite negative electrode sheets, as well as their thickness on the composite separator, are detailed in Examples 1-13 in the table below.

[0079] Table 1: Performance of Semi-Solid-State Batteries

[0080] This table compares the performance data of Examples 1-5 with those of Examples 1-13, visually demonstrating the advantages of the proposed technology in terms of "fast charging rate, cycle stability, and energy density." The proposed technology allows for flexible addition of solid electrolytes, with amounts ranging from 1% to 5% in the composite positive electrode, 1% to 5% in the composite negative electrode, and a solid electrolyte thickness of 1-2 μm in the composite separator. Furthermore, the technology optimizes the transport path through magnetic field-oriented alignment. As can be seen from the comparison, the proposed technology significantly improves the battery's fast charging capability and cycle stability without sacrificing energy density. The fast charging rate is significantly improved: up to 8C (Examples 3 and 13), which is 2.6 times higher than the comparative example 3C; Cyclic stability optimization: Capacity retention rate after 1000 cycles is 87.5%-93.5%, with the highest value (Example 13) being 7 percentage points higher than the peak value of the comparative example; Energy density is significantly improved: ranging from 310 to 420 Wh / kg, with Example 10 reaching 420 Wh / kg, a 50% increase compared to the highest value in the comparative example (280 Wh / kg); Outstanding synergistic performance: It achieves three-dimensional synergy of "ultra-fast charging (5C-8C) + high energy density (above 310Wh / kg) + long cycle life (retention rate above 87.5%)", solving the industry problems of "thick electrode sheets inevitably sacrifice rate" and "high pressure compaction easily leads to poor wetting" in traditional technologies.

[0081] The core of the aforementioned performance improvement stems from the design of "one-dimensional solid electrolyte fibers forming a vertical lithium-ion transport channel in the electrode". This channel shortens the lithium-ion transport distance, reduces the internal resistance of the electrode, and improves the electrolyte wetting efficiency, ultimately achieving synergistic optimization of "ultra-fast charging, high energy density, and long cycle life".

[0082] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing a solid electrolyte, characterized in that, The method includes: The nano-magnetic material was mixed with the lithium-ion solid electrolyte precursor liquid to obtain the first mixed solution; One-dimensional conductive carbon fiber is mixed with the first mixed solution to obtain a second mixed solution; The second mixed solution is sintered to obtain the solid electrolyte.

2. The method for preparing a solid electrolyte according to claim 1, characterized in that, The process of mixing the nanomagnetic material with the lithium-ion solid electrolyte precursor liquid to obtain a first mixed solution includes: The nanomagnetic material was ball-milled and mixed with the lithium-ion solid electrolyte precursor liquid to obtain the first mixed solution.

3. The method for preparing a solid electrolyte according to claim 1, characterized in that, The step of mixing one-dimensional conductive carbon fiber with the first mixed solution to obtain a second mixed solution includes: The one-dimensional conductive carbon fiber placed in a template of a preset material is placed into the first mixed solution to obtain the second mixed solution.

4. The method for preparing a solid electrolyte according to claim 3, characterized in that, The preset material is one or more of polyethylene oxide, polyvinyl alcohol, polyvinyl butyral, paraffin wax, or epoxy resin; the sintering temperature is 600-1050℃.

5. The method for preparing a solid electrolyte according to claim 1, characterized in that, The nanomagnetic material is one or more of Fe3O4 nanoparticles, nickel nanoparticles, and Au-Fe3O4 nanomaterials composed of Fe3O4 and gold. The mass ratio of the nanomagnetic material to the lithium-ion solid electrolyte precursor material in the lithium-ion solid electrolyte precursor liquid is 0.1~3:

100.

6. The method for preparing a solid electrolyte according to any one of claims 1-5, characterized in that, The lithium-ion solid electrolyte precursor fluid is one or more combinations of LATP, LAGP, LLZO, LLTO, or LLZTO.

7. A solid electrolyte, characterized in that, The solid electrolyte is prepared by the method for preparing solid electrolyte according to any one of claims 1-6.

8. The solid electrolyte according to claim 7, characterized in that, The solid electrolyte is a solid electrolyte with the one-dimensional conductive carbon fiber as the skeleton and the surface coated with a nano-magnetic material-solid electrolyte composite layer.

9. A method for preparing a composite positive electrode, characterized in that, include: The positive electrode powder, conductive agent, binder and solid electrolyte as described in claim 7 are mixed to obtain the positive electrode coating material; The positive electrode coating material is coated onto the positive electrode current collector; The positive electrode current collector coated with the positive electrode coating material is placed in a preset magnetic field and dried to obtain the composite positive electrode sheet.

10. A composite positive electrode, characterized in that, The composite positive electrode sheet is prepared by the method described in claim 8.

11. A method for preparing a composite negative electrode, characterized in that, include: Thickener, negative electrode powder, conductive agent, binder and solid electrolyte as described in claim 7 are mixed to obtain negative electrode coating material; The negative electrode coating material is coated onto the negative electrode current collector; The current collector coated with the coating material is placed in a preset magnetic field and dried to obtain the composite negative electrode sheet.

12. A composite negative electrode, characterized in that, The composite negative electrode sheet is prepared by the method described in claim 11.

13. A method for preparing a composite diaphragm, characterized in that, include: The binder and the solid electrolyte as described in claim 7 are mixed to obtain a membrane coating material; The diaphragm coating material is coated onto the base film; The base film coated with the diaphragm coating material is placed in a preset magnetic field and dried to obtain the composite diaphragm.

14. A composite diaphragm, characterized in that, The composite diaphragm is prepared by the method described in claim 13.

15. A semi-solid-state battery, characterized in that, include: A positive electrode, a negative electrode, a separator spaced between the positive and negative electrode, and an electrolyte, characterized in that the positive electrode is the composite positive electrode as described in claim 10; and / or, The negative electrode is the composite negative electrode as described in claim 12; and / or, The diaphragm is the composite diaphragm as described in claim 14.

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