One-dimensional solid-state electrolyte and method of making, corresponding product preparation method and battery

Abstract

This invention relates to the field of battery technology, aiming to solve the problems of weak fast-charging capability and poor cycle stability in existing solid-state batteries due to disordered ion transport paths. It discloses a one-dimensional solid-state electrolyte, its corresponding products, preparation method, and solid-state battery. The method for preparing the one-dimensional solid-state electrolyte includes: mixing a polymer solution with a solid-state electrolyte precursor to obtain a mixed solution; using a solution-blown spinning process to form a continuous jet from the mixed solution; heating to evaporate the solvent to obtain a fibrous composite; and calcining the fibrous composite to obtain the one-dimensional solid-state electrolyte. This method, by combining solution-blown spinning and calcination, prepares a one-dimensional solid-state electrolyte with directional ion transport channels. Using this electrolyte, directional composite electrodes and composite solid-state electrolyte membranes can be prepared, and then fabricated into solid-state batteries, significantly improving lithium-ion transport efficiency and structural stability, while also exhibiting high safety and long cycle life.

Description

Technical Field

[0001] This invention relates to the field of battery technology, and in particular to a one-dimensional solid electrolyte, its preparation method, the preparation method of the corresponding product, and the battery. Background Technology

[0002] With the upgrading of electric vehicles towards longer range and faster charging, and the rapid development of emerging fields such as electric aviation, the market has placed higher demands on the energy density, fast charging performance, and safety and reliability of rechargeable batteries. Traditional commercial lithium-ion batteries use organic liquid electrolytes, which, while possessing advantages such as good electrode wettability and high lithium-ion conductivity, have serious safety hazards such as high risk of thermal runaway, poor tolerance to mechanical abuse, and strong sensitivity to electrical abuse, making them difficult to meet the needs of high-end applications. Therefore, developing all-solid-state batteries that combine high safety, long cycle life, and high energy density has become the core direction of rechargeable battery technology development.

[0003] In the fabrication process of all-solid-state batteries, the dry process is considered one of the optimal solutions for the large-scale production of all-solid-state cells because it does not require the addition of organic solvents, thus avoiding side reactions and active material consumption caused by organic reagents. It also boasts advantages such as simple process, controllable electrode thickness, low production cost, and high active material loading. However, existing dry-process all-solid-state batteries face key technical bottlenecks: since the cells do not contain liquid electrolytes, lithium ions must be transported at the solid-solid interface between the positive electrode, solid electrolyte membrane, and negative electrode. Traditional solid electrolytes exhibit a disordered dispersion in the membrane and electrodes, lacking an ordered transport path, resulting in extremely low lithium-ion transport efficiency and severely limiting the fast-charging capability of solid-state batteries. Simultaneously, the structural strength of the electrodes and solid electrolyte membrane is insufficient, making them prone to cracking and delamination due to volume expansion and contraction during long-term cycling, further exacerbating the problem of poor cycle stability.

[0004] In existing technologies, to improve lithium-ion transport and structural stability, related solutions mainly focus on optimizing the composition of solid electrolytes (such as sulfide and oxide-based solid electrolytes) or adjusting the electrode mixing ratio, but do not address the fundamental design of the transport path. Some solutions attempt to use fibrous solid electrolytes to improve transport efficiency, such as preparing solid electrolyte fibers through electrospinning processes. However, these fibers are mostly randomly dispersed in the electrode / film, failing to form directional lithium-ion transport channels, and still cannot solve the problems of long transport distance and high internal resistance. In addition, the existing fibrous electrolyte preparation process is complex and costly, and it is difficult to ensure structural uniformity when subsequently combined with electrode materials, resulting in limited improvement in electrode strength. Volume deformation during cycling cannot be effectively buffered, and the cycle life and fast charging performance of the battery still do not meet the requirements for practical application.

[0005] In summary, existing dry fabrication technologies for all-solid-state batteries suffer from weak fast-charging capabilities and poor cycle stability due to the lack of ordered lithium-ion transport channels and insufficient strength of the electrode and electrolyte membrane structures, making it impossible to simultaneously achieve high energy density and safety reliability. Therefore, developing a technical solution that can construct efficient lithium-ion transport paths while enhancing electrode structural stability has become crucial for promoting the industrial application of all-solid-state batteries. Summary of the Invention

[0006] This invention provides a one-dimensional solid electrolyte, its corresponding products, preparation method, and solid battery, aiming to solve the technical problem of long lithium-ion transport paths in existing solid batteries.

[0007] To achieve the above-mentioned objective, the first aspect of this invention provides a method for preparing a one-dimensional solid electrolyte, comprising the following steps: The polymer solution was mixed with the solid electrolyte precursor to obtain a mixed solution; Using a solution-blown spinning process, the mixed solution is formed into a continuous jet, and the jet is heated to evaporate the solvent in the jet, thereby obtaining a fibrous composite. The fibrous composite was calcined to obtain the one-dimensional solid electrolyte.

[0008] A second aspect of the present invention provides a one-dimensional solid electrolyte, wherein the one-dimensional solid electrolyte is prepared by the above-described method for preparing one-dimensional solid electrolyte.

[0009] A third aspect of this invention provides a method for preparing a positive electrode film, comprising the following steps: The positive electrode powder, conductive agent, binder and the above-mentioned one-dimensional solid electrolyte are mixed to obtain a positive electrode mixture; The positive electrode mixture is subjected to differential rolling to form a one-dimensional solid electrolyte horizontally oriented positive electrode film.

[0010] A fourth aspect of this invention provides a method for preparing a positive electrode composite film, comprising the following steps: The above-mentioned positive electrode film is folded multiple times or stacked in multiple layers and compacted to obtain a positive electrode film block; wherein the one-dimensional solid electrolyte in each layer of the positive electrode film has the same orientation; The positive electrode film block is cut along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the positive electrode composite film.

[0011] The fifth aspect of this invention provides a method for preparing a negative electrode film, comprising the following steps: The negative electrode powder, conductive agent, binder and the above-mentioned one-dimensional solid electrolyte are mixed to obtain a negative electrode mixture; The negative electrode mixture is subjected to differential rolling to form a one-dimensional solid electrolyte horizontally oriented negative electrode film.

[0012] The sixth aspect of this invention provides a method for preparing a negative electrode composite film, comprising the following steps: The negative electrode film prepared above is folded multiple times or stacked in multiple layers and compacted to obtain a negative electrode film block; wherein the one-dimensional solid electrolyte in each layer of the negative electrode film has the same orientation. The negative electrode film block is cut along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the negative electrode composite film.

[0013] The seventh aspect of this invention provides a method for preparing a first-form composite solid electrolyte, comprising the following steps: The sulfide solid electrolyte, binder and the above-mentioned one-dimensional solid electrolyte are mixed to obtain a solid electrolyte mixture; The solid electrolyte mixture is subjected to differential rolling to form a composite solid electrolyte of the first form in which one-dimensional solid electrolytes are horizontally oriented.

[0014] The eighth aspect of this invention discloses a method for preparing a composite solid electrolyte membrane, comprising the following steps: The first-morph composite solid electrolyte prepared above is folded multiple times or stacked in multiple layers and compacted to obtain a second-morph composite solid electrolyte; wherein the one-dimensional solid electrolyte in each layer of the first-morph composite solid electrolyte has the same orientation. The composite solid electrolyte of the second form is cut along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the composite solid electrolyte membrane.

[0015] A ninth aspect of the present invention provides a solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte membrane spaced between the positive electrode and the negative electrode; The positive electrode sheet is a positive electrode composite sheet in which the positive electrode composite film prepared above is attached to both sides of the positive electrode current collector; and / or, The negative electrode sheet is a negative electrode composite sheet in which the negative electrode composite film prepared above is attached to both sides of the negative electrode current collector; and / or, The solid electrolyte membrane is the composite solid electrolyte membrane prepared above.

[0016] Beneficial effects: The one-dimensional solid electrolyte, its corresponding products, preparation method, and solid-state battery of this invention achieve multi-dimensional breakthroughs in ion transport efficiency, cycle stability, energy density, safety, and process compatibility through the innovative design of "directional arrangement of one-dimensional solid electrolyte + dry composite process," as detailed below: Breakthrough in ultra-fast charging performance: A one-dimensional directional electrolyte forms a through-type lithium-ion transport channel, which significantly shortens the transmission distance and reduces internal resistance.

[0017] Significantly improved cycle life: One-dimensional fibrous electrolyte forms a "mechanical skeleton", buffer electrode volume expands, and interfacial bonding is strengthened.

[0018] Industry-leading energy density: compatible with 50-95% or more of highly active material loading (such as NCM811, graphite), with no liquid electrolyte consumption.

[0019] Intrinsic safety features: The all-solid system contains no flammable electrolyte, and the one-dimensional oxide electrolyte (such as LLZO) has a wide thermal stability and electrochemical window, so there is no fire or explosion after needle penetration, and the temperature rise is ≤20℃, thus eliminating safety hazards at the source.

[0020] The process is easy to industrialize: solution blow spinning has high production efficiency; differential speed rolling and other processes are dry processes, which are compatible with existing production lines and the parameters are easy to adjust; and it is compatible with multiple systems such as oxides and sulfides, which has technical extensibility and lowers the threshold for industrialization.

[0021] In summary, this invention comprehensively breaks through the performance bottlenecks of solid-state batteries, achieving industry-leading performance in fast charging, cycle life, energy density, safety, and mass production, providing a feasible solution for the commercialization of all-solid-state batteries. Attached Figure Description

[0022] Figure 1 This is a schematic flowchart illustrating a method for preparing a one-dimensional solid electrolyte according to an embodiment of the invention. Figure 2 A schematic flowchart illustrating a method for preparing a positive electrode film according to an embodiment of the invention; Figure 3 This is a schematic flowchart illustrating a method for preparing a positive electrode composite membrane according to an embodiment of the invention. Figure 4 A schematic flowchart illustrating a method for preparing a negative electrode film according to an embodiment of the invention; Figure 5 A schematic flowchart illustrating a method for preparing a negative electrode composite film according to an embodiment of the invention; Figure 6 This is a schematic flowchart illustrating a method for preparing a composite solid electrolyte according to a first embodiment of the invention. Figure 7 This is a schematic flowchart illustrating a method for preparing a composite solid electrolyte membrane according to an embodiment of the invention.

[0023] 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

[0024] 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.

[0025] 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.

[0026] 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.

[0027] Reference Figure 1 This invention provides a method for preparing a one-dimensional solid electrolyte, comprising the following steps: S11: Mix the polymer solution with the solid electrolyte precursor to obtain a mixed solution.

[0028] Polymer solution refers to a homogeneous solution formed by dissolving a polymer in an organic solvent. The polymer plays a role in dispersion, filamentation, and temporary support. The polymer is preferably polyvinylpyrrolidone (PVP), and the organic solvent is preferably N,N-dimethylformamide (DMF). The mass percentage of PVP in the polymer solution is 1%-50%, preferably 10%. This ratio range can balance the viscosity of the solution and the subsequent filamentation effect. If the percentage is too low, it will easily lead to jet breakage. If the percentage is too high, the solvent will be difficult to evaporate.

[0029] Solid electrolyte precursors refer to mixtures of raw materials used to prepare solid electrolytes. They typically contain metal oxides or salts and, after reaction, form a solid electrolyte with ionic conductivity. Preferred for the preparation of Li7La3Zr2O 12High-purity (≥99.9%) oxide precursors of (LLZO), such as LiOH The precursor raw materials, H2O, La2O3, and ZrO2, have a mass ratio of 1%-50% in the mixed solution, preferably 10%. This range ensures that the precursor is uniformly dispersed and forms a micron-sized one-dimensional electrolyte after subsequent calcination.

[0030] In one specific embodiment, 50g of polyvinylpyrrolidone (PVP) polymer was dissolved in 450g of N,N-dimethylformamide (DMF) solvent to form a 10wt.% polymer solution. Then, a high-purity oxide precursor (35g LiOH) was added. H2O, 58.16g La2O3, and 29.32g ZrO2 were used to prepare 100g of Li7La3Zr2O. 12 (LLZO) solid electrolyte material was placed in a ball mill jar for mixing and ball milling at 800 r / min for 4 h to obtain a uniformly dispersed mixed solution.

[0031] The viscosity of the polymer solution and the mechanical force of ball milling ensure uniform dispersion of solid electrolyte precursor particles, preventing agglomeration and laying the foundation for the subsequent formation of continuous fibers.

[0032] S12: Using a solution blow spinning process, the mixed solution is formed into a continuous jet, and the jet is heated to evaporate the solvent in the jet, thereby obtaining a fibrous composite.

[0033] Solution blow spinning is a technology that uses high-pressure gas to cut a polymer solution into a jet, and then obtains fibers through solvent evaporation. It features high efficiency and controllable fiber diameter. The mixed solution is injected into the storage tank of the blow spinning equipment. The number of internal nozzles in the equipment can be selected from 1 to 10, preferably 1, and can be adjusted according to production capacity requirements. The solution outflow rate from the nozzles is set to 0.1-50 mL / s, preferably 6 mL / s. Too low a rate will reduce spinning efficiency, while too high a rate can easily lead to jet instability. Pressurized gas is introduced into the external nozzles of the blow spinning equipment. The gas can be air, nitrogen, or oxygen, preferably dry air, and the gas pressure is set to 1-10 MPa, preferably 5 MPa. The pressure drop and cutting force generated by the high-pressure gas cause the mixed solution to form a continuous jet.

[0034] A continuous jet refers to a solution flow that maintains a continuous shape under the action of gas shearing force, and is an intermediate state for fiber formation.

[0035] In one specific embodiment, the mixed solution is injected into the storage tank of the blown spinning equipment, the jet pressure is set to 5 MPa, and the spinneret diameter is 0.5 mm; a heating channel with a length of 1 m is set below the spinneret, and gradient heating is used (gradually increasing from 80°C to 150°C) so that the DMF solvent gradually evaporates during the jet transmission process, and finally a fibrous composite (containing PVP and solid electrolyte precursor) with a diameter of 1-5 μm is obtained on the collecting drum. The collecting drum can be made of metal or ceramic, preferably Al2O3 ceramic, as ceramic material is heat resistant and does not easily adhere to the fiber.

[0036] High-pressure gas cutting ensures that the solution forms a continuous jet, and gradient heating allows the solvent to evaporate slowly, preventing the fibers from breaking due to rapid shrinkage, ultimately resulting in a fibrous composite with a complete morphology.

[0037] S13: The fibrous composite is calcined to obtain the one-dimensional solid electrolyte.

[0038] Calcination treatment refers to the process of heating materials at high temperatures to remove organic components and promote the reaction and crystallization of inorganic components. A muffle furnace is preferred for calcination, with a heating rate of 1-20℃ / min, preferably 2℃ / min, to avoid rapid heating that could cause fiber structure breakage. The first calcination holding temperature is 400-600℃, preferably 450℃, with a holding time of 0.5-4h, preferably 2h. Too low a temperature or too short a holding time is detrimental to the removal of organic components, while too high a temperature or too long a holding time affects the fiber morphology. The second calcination holding temperature is 800-1200℃, preferably 850℃, with a holding time of 2-8h, preferably 4h. Too low a temperature or too short a holding time will lead to incomplete reaction and the presence of impurities, while too high a temperature or too long a holding time will deteriorate the performance of the one-dimensional solid electrolyte fiber and increase production energy consumption.

[0039] In one specific embodiment, the fibrous composite was placed in a muffle furnace and heated to 450°C at 5°C / min and held for 1 hour to remove PVP; then the temperature was further increased to 850°C at 2°C / min and held for 6 hours to allow the oxide precursor to fully react and crystallize. After natural cooling, a one-dimensional LLZO solid electrolyte with a length of 400-600 μm and a diameter of 0.5-2 μm was obtained.

[0040] Stepwise calcination removes organic polymers to prevent them from interfering with the inorganic phase reaction; high-temperature crystallization ensures the formation of a highly crystalline one-dimensional solid electrolyte, providing an ordered channel for lithium-ion transport.

[0041] In this embodiment, a method for preparing a one-dimensional solid electrolyte via "polymer dispersion-blown spinning-high-temperature calcination crystallization" is employed. The core of this method is utilizing the dispersion and filamentation of polymers, combined with the efficient fiber-forming capability of blow spinning, to ultimately obtain a solid electrolyte with a one-dimensional structure through calcination. Compared to existing technologies, this method can prepare a continuous one-dimensional solid electrolyte without complex equipment, solving the problems of disordered morphology and ion transport pathways in traditional solid electrolytes. The one-dimensional structure provides a directional transport channel for lithium ions, significantly reducing transport resistance. Simultaneously, its fibrous morphology enhances interfacial contact with electrode materials, laying the foundation for improving the fast-charging performance and cycle stability of solid-state batteries.

[0042] Furthermore, after calcination, the one-dimensional solid electrolyte is screened: compressed air is used for screening, with the blowing pressure set to 1-10 MPa, preferably 2 MPa, to screen out one-dimensional solid electrolyte materials with a length of 400-600 μm and a diameter of 0.5-2 μm. Fibers that are too short (<400 μm) or too long (>600 μm) are removed to ensure the orientation consistency during the subsequent preparation of composite membranes.

[0043] In one embodiment, heating the jet to cause the solvent in the jet to evaporate includes heating the jet using a gradient heating method to cause the solvent in the jet to evaporate.

[0044] Gradient heating refers to a heating method in which a gradually increasing temperature field is set along the jet transmission direction, allowing the solvent to gradually evaporate at different temperature stages. A heating channel with a length of 0.5-5m, preferably 1m, is set below the spinneret. In one embodiment, the channel is equipped with a heating device only at the tail end, allowing the jet to pass through the temperature gradient and evaporate the solvent. The heating temperature at the tail end of the channel is set to 30-350℃, preferably 150℃. Gradient heating can prevent the solvent from boiling over and causing the fiber to bubble or break, ensuring that the jet gradually solidifies during transmission.

[0045] In another specific embodiment, during the blow spinning step, the heating channel is divided into three sections: the first section (0-30cm) at 80°C, the second section (30-70cm) at 120°C, and the third section (70-100cm) at 150°C. The mixed solution jet passes through the three heating zones sequentially. The DMF solvent initially evaporates in the low-temperature section, causing the jet to solidify and take shape. In the medium-temperature section, it further evaporates, reducing the internal porosity of the fibers. Finally, in the high-temperature section, residual solvent is completely removed, resulting in a smooth-surfaced, densely structured fibrous composite. This gradient heating avoids solvent boiling caused by a single high temperature (which would cause fiber bubbling and breakage) and solvent residue caused by a single low temperature (which would affect subsequent calcination), ensuring the fiber morphology is intact and the internal structure is uniform, thus improving the mechanical properties and ionic conductivity of the one-dimensional solid electrolyte.

[0046] In one embodiment, the above-mentioned mixing of polymer solution with solid electrolyte precursor to obtain mixed solution includes: mixing polymer solution and solid electrolyte precursor and then ball milling to obtain uniformly dispersed mixed solution.

[0047] Ball milling is a physical dispersion method that uses the collision and friction between grinding balls and materials to refine and uniformly mix material particles. Mixing equipment can include planetary ball mills, drum ball mills, or dry mixers, with variable frequency planetary ball mills being preferred. The ball mill speed should be set at 200-1500 r / min, preferably 800 r / min, and the milling time at 2-8 hours, preferably 4 hours. For dry mixers, liquid cooling should be used to control the mixing temperature at 0-60℃, preferably 10℃, to avoid excessively high temperatures during mixing that could lead to polymer denaturation or solvent evaporation, ultimately resulting in a uniformly dispersed solution without significant agglomeration.

[0048] In one specific embodiment, in the mixing step of the above embodiments, a variable frequency planetary ball mill is used to mix the PVP / DMF solution with the LLZO precursor (LiOH). H2O, La2O3, and ZrO2 were added to a zirconia ball mill jar, and zirconia balls with a diameter of 5 mm were added at a ball-to-material ratio of 5:1. The milling speed was set to 800 r / min, and the milling was carried out for 4 hours. During the ball milling process, the mechanical force of the grinding balls broke up the agglomerates of precursor particles, and the PVP molecular chains adsorbed on the particle surface to form steric hindrance, ultimately resulting in a homogeneous mixed solution with no obvious particle sedimentation (particle size distribution D50 = 1.2 μm). The ball milling treatment, combined with the dispersion effect of the polymer, can refine the precursor particles to the micron level and disperse them uniformly, avoiding uneven spinning jets caused by particle agglomeration in the mixed solution. This ensures that the subsequent fibers have consistent diameter and uniform composition, providing a prerequisite for the subsequent spinning preparation of morphologically stable fibrous composites, thereby ensuring the batch stability of the one-dimensional solid electrolyte and reducing the internal resistance fluctuation of the solid-state battery.

[0049] In one embodiment, the calcination treatment of the fibrous composite to obtain the one-dimensional solid electrolyte comprises: S131: The fibrous composite is heated at a first temperature to remove the polymer from the fibrous composite, wherein the first temperature is lower than the second temperature.

[0050] The first temperature refers to the temperature range sufficient to decompose and volatilize the polymer (such as PVP) without affecting the stability of the inorganic precursor (typically 400-600℃).

[0051] In one specific embodiment, during the calcination step of the above embodiment, the first temperature is set to 450°C: the fibrous composite is placed in a muffle furnace and heated to 450°C at a rate of 5°C / min, and held at this temperature for 1 hour. At this temperature, PVP decomposes into gases such as CO2 and H2O, which completely volatilize, leaving an amorphous LLZO precursor as the remaining inorganic matter (no obvious diffraction peaks detected by XRD). Precise control of the first temperature can completely remove the polymer and prevent premature reaction of the precursor, thus preventing organic residues from interfering with subsequent crystallization.

[0052] S132: The fibrous composite with removed polymer is crystallized using a second temperature to obtain the one-dimensional solid electrolyte.

[0053] The second temperature refers to the temperature range above the first temperature that can induce the inorganic precursor to undergo a chemical reaction and crystallize to form the target solid electrolyte (usually 800-1200℃).

[0054] In one specific embodiment, after removing the polymer, the temperature is further increased to 850°C (second temperature) at a rate of 5°C / min, and held at this temperature for 1-6 hours. At this point, LiOH... H2O, La2O3, and ZrO2 undergo a solid-state reaction to generate LLZO with a cubic phase structure. After cooling, a one-dimensional LLZO solid electrolyte is obtained.

[0055] High-temperature crystallization ensures that the precursor reacts fully and forms a highly crystalline solid electrolyte, improving ionic conductivity; stepwise heating avoids fiber breakage caused by sudden temperature changes, maintaining the integrity of the one-dimensional structure.

[0056] In this embodiment, segmented temperature control resolves the contradiction of "incomplete polymer removal" or "destruction of fiber structure" in traditional one-step calcination. While preserving the one-dimensional structure, a high-purity, high-crystallinity solid electrolyte is obtained, ensuring its ion conductivity; simultaneously, interfacial side reactions caused by organic residues are avoided, improving the cycle stability of the solid-state battery.

[0057] This invention also provides a one-dimensional solid electrolyte, which is prepared according to the preparation method of the one-dimensional solid electrolyte according to any of the above embodiments.

[0058] The one-dimensional structure enables the construction of directional lithium-ion transport channels, reducing the ion transport distance by more than 50% compared to traditional particulate solid electrolytes. The fibrous morphology enhances the interfacial contact area with electrode materials and reduces interfacial impedance. Compared to existing technologies, this one-dimensional solid electrolyte solves the problems of "disordered ion transport paths" and "poor interfacial contact" in traditional solid electrolytes, and can be directly used to prepare high-performance composite electrodes and solid-state batteries, significantly improving the battery's fast-charging capability and cycle stability (capacity retention ≥90% after 1000 cycles).

[0059] Reference Figure 2 This invention also provides a method for preparing a positive electrode film, comprising the following steps: S21: Mix the positive electrode powder, conductive agent, binder and the above-mentioned one-dimensional solid electrolyte to obtain a positive electrode mixture.

[0060] The positive electrode powder refers to a positive electrode material with electrochemical activity (such as layered oxides, polyanionic compounds, etc.); the positive electrode powder can be selected from lithium iron phosphate, ternary materials, sodium-ion battery positive electrode materials, or lithium-rich manganese-based materials, preferably high-nickel ternary materials; the mass percentage of the positive electrode powder is 50-99%, preferably 95%; the conductive agent can be selected from one or more of carbon black, carbon nanotubes, and acetylene black, with a mass percentage of 1%-10%, preferably 2%; the binder can be selected from one or more of PVDF, PTFE, PE, PTFE-PVDF composite binder, and PTFE-PE composite binder, with a mass percentage of 0.2%-10%, preferably 2%; the mass percentage of the one-dimensional solid electrolyte is 0.1%-10%, preferably 1%.

[0061] In one specific embodiment, LiNi is taken 0.8 Co 0.1 Mn 0.1 O2 (positive electrode powder, 95wt%), carbon nanotubes (conductive agent, 2wt%), PTFE-PVDF (composite binder, 2wt%), and one-dimensional LLZO electrolyte (1wt%) were mixed at 20℃ for 30 min to obtain a uniform positive electrode mixture (without obvious agglomeration).

[0062] One-dimensional solid electrolytes are uniformly dispersed in the cathode material, laying the foundation for subsequent directional alignment; a small amount of electrolyte mixed in in advance can improve the interfacial compatibility between the cathode and the electrolyte membrane.

[0063] S22: The positive electrode mixture is subjected to differential rolling to form a one-dimensional solid electrolyte horizontally oriented positive electrode film.

[0064] Horizontal orientation refers to the alignment of the axis of a one-dimensional solid electrolyte with the surface of the positive electrode film parallel to the rolling direction (usually the length direction of the positive electrode film), and is formed by the shearing force of differential rolling.

[0065] Differential roller pressing refers to a process in which materials are crushed by two rollers rotating at different speeds, and the fibrous components in the materials are oriented perpendicular to the roller direction by utilizing the speed difference. The roller press can be configured with 2, 3, 4, 6, or 8 rollers, with a 2-roller structure being preferred. The speeds of the two rollers are independently adjustable (0-60 r / min), with the upper roller speed set at 5-30 r / min and the lower roller speed at 10-60 r / min, and the preferred differential speed ratio being 1:2. The roller gap width is 10%-90% of the target film thickness, preferably 70%, the roller pressing temperature is set at 25-140℃, preferably 85℃, and the roller pressing pressure is set at 0-196000 N, preferably 49000 N. As the number of roller pressing cycles increases, under the shearing action of the rollers at different speeds, the one-dimensional solid electrolyte gradually exhibits a horizontally oriented alignment, while the film thickness gradually decreases to 50 μm-5 mm, preferably 500 μm.

[0066] In one specific embodiment, the positive electrode mixture is placed in a differential speed roller press, with the upper roller speed set at 10 r / min and the lower roller speed at 20 r / min (speed difference 1:2), the roller pressing temperature at 85°C, and the pressure at 49,000 N. Under the shear force generated by the speed difference of the rollers, the one-dimensional LLZO electrolyte is oriented along the roller axis (horizontal direction), ultimately obtaining a positive electrode film with a thickness of 100 μm (SEM observation shows that the LLZO fibers are ≥80% ordered in the horizontal direction).

[0067] Differential rolling achieves horizontal orientation of the one-dimensional electrolyte through mechanical shearing, initially constructing ion transport paths that are basically parallel to each other and parallel to the membrane surface, while improving the density and structural strength of the positive electrode membrane.

[0068] In this embodiment, the core principle is to utilize the shearing force of differential rolling to achieve the ordered arrangement of one-dimensional electrolytes. This method solves the problem of disordered electrolyte dispersion in traditional cathode films. The horizontally oriented one-dimensional electrolyte provides lithium ions with a fast channel parallel to the film surface, while simultaneously enhancing the mechanical properties of the cathode film. This lays the foundation for the subsequent preparation of vertically oriented composite films and indirectly improves the rate performance of solid-state batteries.

[0069] This invention also provides a positive electrode film, which is prepared according to the above-described method for preparing a positive electrode film.

[0070] The positive electrode membrane is a functional membrane material prepared by the above-mentioned positive electrode membrane preparation method. Its core feature is that it contains a one-dimensional solid electrolyte arranged in a horizontal orientation. It is mainly composed of positive electrode powder, conductive agent, binder and one-dimensional solid electrolyte, and has good mechanical strength and ion transport capability.

[0071] In one specific embodiment, using 95wt% LiNi 0.8 Co 0.1 Mn 0.1Using O2 (NCM811, positive electrode powder, particle size 5-10μm), 2wt% carbon nanotubes (CNT, diameter 10-20nm, length 5-10μm), 2wt% polytetrafluoroethylene-polyvinylidene fluoride composite binder (PTFE-PVDF, molecular weight 500,000), and 1wt% one-dimensional LLZO electrolyte (length 400-600μm, diameter 0.5-2μm) as raw materials, after mixing at 20℃ and differential rolling (upper roller 10r / min, lower roller 20r / min, 60℃, 10MPa), a positive electrode film with a thickness of 100μm is obtained.

[0072] Scanning electron microscopy (SEM) observations showed that the one-dimensional LLZO electrolyte was oriented along the rolling direction (horizontal direction), with the long axis of the fiber and the membrane surface having an angle of ≤15° (orientation order ≥85%). The NCM811 particles and CNTs formed a continuous conductive network, and the LLZO fibers were uniformly distributed in the gaps between the particles without obvious agglomeration.

[0073] Performance parameters: areal density 20 mg / cm², porosity ≤10%, room temperature ionic conductivity 2.5 × 10⁻⁶ -5 S / cm (1.8 times higher than traditional cathode films with no orientation structure), tensile strength 15MPa (meets the requirements of subsequent stacking processing).

[0074] In this embodiment, the core innovation of this positive electrode film lies in achieving the horizontally oriented arrangement of the one-dimensional solid electrolyte through differential rolling, solving the problems of long ion transport paths and high internal resistance caused by the disordered dispersion of electrolytes in traditional positive electrode films. The beneficial effects are as follows: 1. The horizontally oriented one-dimensional electrolyte provides lithium ions with a fast channel parallel to the film surface, shortening the transport distance and improving the ion migration efficiency inside the positive electrode; 2. The one-dimensional fibers are in close contact with the positive electrode particles, increasing the solid-solid interface area and reducing interface impedance; 3. The fibrous structure enhances the mechanical strength of the positive electrode film, preventing breakage during subsequent processing (such as stacking and cutting), laying the foundation for the preparation of high-performance composite electrodes.

[0075] Reference Figure 3 This invention also provides a method for preparing a positive electrode composite film, comprising the following steps: S31: The above-mentioned positive electrode film is folded multiple times or stacked in multiple layers and compacted to obtain a positive electrode film block; wherein the one-dimensional solid electrolyte in each layer of the positive electrode film has the same orientation.

[0076] Multilayer stacking refers to stacking multiple positive electrode films along the same direction, ensuring that the horizontal orientation of the one-dimensional solid electrolyte in each layer is consistent (e.g., along the length of the film). Multiple folding refers to repeatedly folding a single positive electrode film along the same direction to form a multilayer structure, ensuring that the horizontal orientation of the one-dimensional solid electrolyte in each layer is consistent (e.g., along the length of the film). The number of positive electrode film layers is set to 20-500, preferably 100, ensuring that the edges of each layer are aligned (error ≤ 0.5mm).

[0077] Compaction refers to the process of tightly bonding stacked membrane layers through hot pressing, eliminating interlayer gaps, and forming a monolithic block. The hot pressing temperature is set at 25-150℃, preferably 85℃, the pressure is set at 980N-98000N, preferably 9800N, and the holding time is 10-60min, preferably 30min. After compaction, a positive electrode membrane block with no interlayer gaps and a density of 3.5-3.7g / cm³ is obtained.

[0078] In one specific embodiment, a positive electrode membrane is taken and stacked 50 layers along its length (the orientation direction of the one-dimensional LLZO electrolyte), ensuring that the edges of each layer are aligned (error ≤ 0.5 mm); the stacked membrane layers are placed in a flat plate hot press, and the temperature is set to 85°C and the pressure to 9800 N, and the temperature is held for 30 min to compact it, resulting in a positive electrode membrane block with a thickness of 5 cm and a density of 3.6 g / cm³ (no obvious gaps between layers, and a dense overall structure).

[0079] Multilayer stacking creates densely distributed "potential channels" of one-dimensional electrolytes in the vertical direction. Compaction ensures strong interlayer bonding, preventing delamination during subsequent cutting, while also increasing overall density to reduce ion transport resistance.

[0080] S32: Cut the positive electrode film block along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the positive electrode composite film.

[0081] The perpendicular cutting direction refers to the cutting surface being perpendicular to the horizontal orientation direction of the one-dimensional solid electrolyte (if the electrolyte is oriented along the length direction, then it is cut along the width direction), so that in the cut composite membrane, the axis of the one-dimensional electrolyte is perpendicular to the surface of the composite membrane (i.e., along the thickness direction of the membrane).

[0082] In one specific embodiment, a precision cutting machine was used to cut the LLZO electrolyte in the positive electrode film block along a direction perpendicular to the orientation of the LLZO electrolyte, with a cutting thickness of 150 μm, to obtain the positive electrode composite film. SEM observation showed that the axis of the LLZO electrolyte was perpendicular to the surface of the composite film (angle ≥ 85°), the vertical orientation order was ≥ 90%, and the fibers were uniformly distributed in the film without breakage due to cutting.

[0083] Vertical cutting transforms the original horizontally oriented one-dimensional electrolyte into an oriented structure perpendicular to the membrane surface, constructing a lithium-ion transport channel that runs through the thickness direction of the cathode composite membrane. This completely solves the problem of ions needing to be transported in a roundabout manner in the traditional cathode, significantly reducing transport resistance.

[0084] In this embodiment, the core step in achieving "high-speed lithium-ion transport across the membrane" is to transform the horizontally oriented one-dimensional electrolyte in the positive electrode film into a vertically oriented one-dimensional electrolyte through a combination of "stacking and compaction - vertical cutting" processes. Compared with existing technologies, this method can achieve vertical alignment of the electrolyte without complex equipment, solving the problems of high cost and low efficiency of traditional orientation methods (such as magnetic field induction and electric field induction). The beneficial effects are as follows: 1. The vertically oriented one-dimensional electrolyte forms a "direct" ion channel, allowing lithium ions to be directly transported from one side of the composite membrane to the other, significantly improving the transport efficiency; 2. Multi-layer stacking increases the volume ratio of the one-dimensional electrolyte, enhancing the continuity of the ion conduction network; 3. The compaction and cutting processes ensure that the composite membrane structure is dense and strong, adapting to the volume changes during long-term cycling of solid-state batteries.

[0085] This invention also provides a positive electrode composite membrane, which is prepared according to the above-described method for preparing a positive electrode composite membrane.

[0086] The core value of this cathode composite film lies in its "vertically oriented one-dimensional electrolyte channel," which solves the key pain points of "high solid-solid interface impedance" and "poor ion transport" between the cathode and electrolyte membrane in solid-state batteries. The overall beneficial effects are: 1. The vertical channel significantly shortens the lithium-ion transport distance in the cathode composite film, significantly improving cathode reaction kinetics and supporting high-rate charging of 4C and above; 2. The one-dimensional LLZO electrolyte has high chemical stability, good compatibility with NCM811 and solid-state electrolyte membranes, reduces interfacial side reactions, and improves cycle stability; 3. The dense structure and the "skeleton effect" of the vertical fibers can buffer the volume expansion of NCM811 during cycling (approximately 3-5%), preventing membrane cracking and extending battery life.

[0087] This invention also provides a positive electrode composite sheet, including a positive electrode current collector, with the above-mentioned positive electrode composite film attached to both sides of the positive electrode current collector.

[0088] This positive electrode composite electrode is composed of a positive current collector and positive electrode composite films on both sides. It is the core positive electrode component of solid-state batteries, integrating electron collection (current collector) and ion transport (composite film) functions, and has high energy density and structural stability.

[0089] Positive current collector refers to the conductive substrate used to collect electrons generated by the positive electrode. It is usually aluminum foil (Al) and has good conductivity and chemical stability.

[0090] In one specific embodiment, an aluminum foil with a thickness of 12 μm (purity 99.9%) is used as the positive electrode current collector. A positive electrode composite film (150 μm thick) is laid flat on both sides of the aluminum foil, ensuring that the edge of the composite film is aligned with the aluminum foil (error ≤ 1 mm). The film is placed in a hot press and hot-pressed at 85°C and 98,000 N for 20 min to make the composite film and the aluminum foil tightly bonded (peel strength ≥ 0.5 N / cm), thus obtaining a positive electrode composite sheet (total thickness 312 μm).

[0091] The positive electrode composite sheet in this embodiment solves the problems of "separation of electron / ion transport paths" and "weak interface bonding" in traditional positive electrode sheets through the integrated design of "current collector-composite film". The overall beneficial effects are: 1. The composite film on both sides of the current collector is symmetrically distributed, ensuring uniform current distribution during charging and discharging and avoiding local overheating; 2. The composite film and current collector are tightly bonded by hot pressing, reducing the interface contact resistance and improving the overall mechanical strength of the electrode sheet, adapting to the mechanical stress during battery assembly and cycling; 3. The combination of high-load positive electrode powder (95wt%) and efficient ion transport channels significantly improves the energy density of the electrode sheet while ensuring fast charging performance, laying the foundation for long-range solid-state batteries.

[0092] Reference Figure 4 This invention also provides a method for preparing a negative electrode film, comprising the following steps: S41: Mix the negative electrode powder, conductive agent, binder and the above-mentioned one-dimensional solid electrolyte to obtain a negative electrode mixture.

[0093] The negative electrode powder refers to a negative electrode material with lithium storage capacity (such as carbon materials, silicon-based materials, etc.). In this embodiment, it is graphite (layered structure, capable of embedding lithium ions). The mass percentage of the negative electrode powder is 50-99%, preferably 95%; the conductive agent can be superconducting carbon black (SP) or carbon nanotubes, with a mass percentage of 1%-10%, preferably 2%; the binder can be styrene-butadiene rubber (SBR) or PVDF, with a mass percentage of 0.2%-10%, preferably 2%; and the mass percentage of the one-dimensional solid electrolyte is 0.1%-10%, preferably 1%.

[0094] In one specific embodiment, 95 wt% of natural graphite (the main negative electrode powder, with a particle size of 10-20 μm), 2 wt% of superconducting carbon black (SP, with a particle size of 30-50 nm), 2 wt% of polytetrafluoroethylene-polyethylene composite binder (PTFE-PE), and 1 wt% of the one-dimensional LLZO electrolyte from Example 5 were added to deionized water as a dispersion medium and stirred at 30°C for 60 min (500 r / min) to obtain a uniform negative electrode mixture (50% solid content, no sedimentation).

[0095] One-dimensional LLZO electrolyte is uniformly dispersed between graphite particles, using its fibrous morphology to fill the gaps between graphite particles. At the same time, the SBR binder can encapsulate the fibers and particles, initially constructing a stable mixed system, which provides a basis for subsequent directional alignment.

[0096] S42: The negative electrode mixture is subjected to differential rolling to form a one-dimensional solid electrolyte horizontally oriented negative electrode film.

[0097] In one specific embodiment, a differential speed roller press (preferably a 2-roller structure) is used, which is the same as that used for the positive electrode membrane. The roller pressing temperature is set to 25-80℃, preferably 50℃, the roller pressing pressure is set to 0-147000 N, preferably 78400 N, and the roller gap width is 10%-90% of the target membrane thickness, preferably 70%. Through a "folding-thinning-repetition" cycle (folding 2-5 times, repeating 0-5 times), a negative electrode membrane with a thickness of 50μm-3mm, preferably 80μm, and a one-dimensional solid electrolyte horizontally oriented arrangement is finally obtained.

[0098] SEM observation shows that the one-dimensional LLZO electrolyte is oriented along the rolling direction (horizontal direction) (order degree ≥80%), the graphite particles are stacked in layers due to the rolling action, and the LLZO fibers are distributed between the graphite layers and the particle gaps, without conflicting with the conductive network formed by SP.

[0099] The shearing force of differential rolling causes the one-dimensional electrolyte to orient in the horizontal direction, providing a channel for the lateral transport of lithium ions in the negative electrode film; at the same time, rolling causes the graphite particles to be tightly stacked, increasing the density of the negative electrode film and reducing the volume expansion during charging and discharging.

[0100] In this embodiment, the horizontal orientation of the one-dimensional electrolyte in the negative electrode film is achieved. Compared with existing negative electrode film preparation methods, its advantages are: 1. The horizontally oriented LLZO fibers can guide lithium ions to transport along the graphite interlayer direction, matching the lithium ion insertion path (interlayer diffusion) of graphite and improving the negative electrode reaction kinetics; 2. The mechanical strength of LLZO fibers can alleviate interlayer delamination during graphite cycling and reduce capacity decay; 3. The dry differential rolling process avoids the solvent residue problem of traditional wet coating, improves the purity and safety of the negative electrode film, and is suitable for the liquid-free system of all-solid-state batteries.

[0101] This invention also provides a negative electrode film, which is prepared by the above-described method for preparing a negative electrode film.

[0102] This negative electrode film is a product of the above-mentioned negative electrode film preparation method. Its core feature is that it contains a horizontally oriented one-dimensional solid electrolyte, which is composed of graphite, conductive agent, binder and LLZO fiber. It is adapted to the negative electrode requirements of solid-state batteries and has the characteristics of low impedance and anti-expansion.

[0103] In one specific embodiment, the negative electrode film has a thickness of 80 μm and is composed of 95 wt% graphite, 2 wt% SP, 2 wt% PTFE-PE composite binder, and 1 wt% horizontally oriented LLZO fibers.

[0104] X-ray diffraction (XRD) showed that the (002) peak of graphite had high intensity (intact layered structure), and the characteristic peak of LLZO was not shifted (stable structure); SEM showed that LLZO fibers were arranged along the rolling direction, with the long axis and the film surface having an angle of ≤20°, and the fibers were in close contact with the graphite particles (gap ≤100nm).

[0105] This negative electrode film solves the problems of "slow lithium-ion transport" and "structural damage caused by volume expansion" in solid-state battery negative electrodes through the synergistic effect of horizontally oriented one-dimensional electrolyte and graphite. The overall beneficial effects are as follows: 1. Horizontally oriented LLZO fibers provide a fast transport channel for lithium ions along the graphite layers, reducing the internal resistance of the negative electrode and improving the battery rate performance (supporting 4C discharge); 2. The fibrous structure forms "mechanical support" between graphite particles, inhibiting interlayer expansion and particle shedding during cycling, and extending the life of the negative electrode; 3. It has good compatibility with solid electrolyte membranes, low interfacial impedance, and reduces interfacial side reactions.

[0106] Reference Figure 5 This invention also provides a method for preparing a negative electrode composite film, comprising the following steps: S51: The above-mentioned negative electrode film is folded multiple times or stacked in multiple layers and compacted to obtain a negative electrode film block; wherein the one-dimensional solid electrolyte in each layer of negative electrode film has the same orientation.

[0107] In one specific embodiment, the above-mentioned negative electrode film is taken and stacked in 40 layers along the horizontal orientation direction (LLZO fiber arrangement direction). After aligning the edges, it is placed in a flat hot press. The temperature is set at 70°C and the pressure at 7840 N, and the heat is maintained for 25 min to obtain a negative electrode film block with a thickness of 3.2 cm and a density of 1.85 g / cm³ (the interlayer bonding is tight and there are no air bubbles).

[0108] Multi-layer stacking enables LLZO fibers to form a dense distribution in the vertical direction. The compaction process ensures interlayer bonding through a gentle temperature, while providing a material block of sufficient thickness for subsequent cutting, thus ensuring the uniformity of the composite film.

[0109] S52: Cut the negative electrode film block along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the negative electrode composite film.

[0110] In one specific embodiment, the negative electrode film block was cut along a direction perpendicular to the LLZO fiber orientation to obtain a negative electrode composite film with a thickness of 120 μm. SEM showed that the LLZO fibers were arranged perpendicularly along the thickness direction of the composite film (vertical order ≥88%), and the fibers were interwoven between the graphite layers without disrupting the layered structure of the graphite.

[0111] Vertical cutting transforms horizontally oriented fibers into vertical channels, allowing lithium ions to be directly transported from the surface of the negative electrode composite film to its interior. This matches the vertical ion transport path of the "electrolyte film-negative electrode" in solid-state batteries. At the same time, the vertical distribution of fibers can better buffer the volume expansion of graphite (along the thickness direction).

[0112] In this embodiment, considering the characteristics of the negative electrode material (graphite volume expansion is mainly along the thickness direction), the vertical orientation of the one-dimensional electrolyte is achieved through "low-temperature flexible compaction + vertical cutting," solving the problem of "conflict between ion transport and anti-expansion requirements" in traditional negative electrode composite films. The overall beneficial effects are: 1. Vertically oriented LLZO fibers construct ion channels throughout the negative electrode composite film, shortening the lithium-ion transport distance and improving the fast-charging response speed of the negative electrode; 2. Vertically distributed fibers form "support pillars" in the thickness direction, effectively suppressing thickness expansion during graphite cycling (expansion rate reduced to below 5%); 3. The process is mild (maximum temperature 70°C), avoiding structural damage to the negative electrode material (such as graphite) and ensuring its lithium storage performance.

[0113] This invention also provides a negative electrode composite film, which is prepared according to the above-described method. Its core feature is that the one-dimensional solid electrolyte is vertically oriented along the thickness direction, adapting to the ion transport and structural stability requirements of solid-state battery negative electrodes.

[0114] In one specific embodiment, the negative electrode composite film has a thickness of 120 μm and is composed of 95 wt% graphite, 2 wt% SP, 2 wt% PTFE-PE composite binder, and 1 wt% vertically oriented LLZO fibers.

[0115] Cross-sectional SEM showed that LLZO fibers vertically penetrated the composite membrane, with both ends connecting to the upper and lower surfaces of the membrane, respectively. The contact area between the fibers and graphite particles increased compared to the horizontal orientation.

[0116] In this embodiment, the negative electrode composite film, through a vertically oriented one-dimensional electrolyte, simultaneously meets the dual requirements of "high-speed ion transport" and "resistance to volume expansion" for solid-state battery negative electrodes, solving the performance limitations of existing negative electrode materials in solid-state systems. The overall beneficial effects are as follows: 1. The vertical channels significantly improve the diffusion rate of lithium ions in the negative electrode composite film, enabling the negative electrode to match the high-rate requirements of the positive electrode (no significant lithium dendrite formation during 4C charging); 2. The vertically distributed LLZO fibers enhance the composite film's resistance to deformation; the volume expansion of graphite during cycling is "absorbed" by the fibers, preventing a surge in interfacial impedance caused by film cracking; 3. It exhibits good compatibility with the positive electrode composite film and electrolyte film, forming a full-cell-level vertical ion transport network, thus improving the overall performance of the solid-state battery.

[0117] This invention also provides a negative electrode composite electrode sheet, including a negative electrode current collector, with the aforementioned negative electrode composite film attached to both sides of the negative electrode current collector. This negative electrode composite electrode sheet is composed of a negative electrode current collector (copper foil) and negative electrode composite films on both sides, and is a core negative electrode component of a solid-state battery, possessing both electron collection and ion transport functions, adapting to high-rate and long-cycle requirements.

[0118] Negative electrode current collector refers to the conductive substrate used to collect electrons generated by the negative electrode. It is usually copper foil (Cu) and has good conductivity and stability against lithium.

[0119] In one specific embodiment, an 8μm thick electrolytic copper foil (99.9% purity) was used as the negative electrode current collector. The above-mentioned negative electrode composite film (120μm thick) was applied to both sides of the copper foil and hot-pressed at 70℃ and 8t for 15min to obtain a negative electrode composite electrode sheet (total thickness 248μm, peel strength ≥0.4N / cm).

[0120] Cross-sectional SEM showed that there was no gap between the copper foil and the composite film interface, one end of the LLZO fiber was in contact with the copper foil surface (ensuring that ions could be transported to the vicinity of the current collector), and the SP conductive network was well connected to the copper foil (smooth electron transport).

[0121] In this embodiment, the negative electrode composite sheet solves the problems of "electron / ion transport mismatch" and "poor structural stability during cycling" of traditional negative electrode sheets through the structural design of "copper foil-vertically oriented composite film". The overall beneficial effects are: 1. The composite film on both sides of the copper foil is symmetrically distributed, ensuring uniform current during charging and discharging and avoiding local lithium deposition (suppressing lithium dendrites); 2. The vertically oriented LLZO fibers are in direct contact with the copper foil, reducing the resistance of ion transport to the current collector and improving the fast charging response speed; 3. The strong bonding force between the composite film and the copper foil and the supporting effect of the fibers enable the electrode sheet to withstand long-term cycling mechanical stress (no delamination after 1000 cycles), significantly extending battery life.

[0122] Reference Figure 6 The present invention also provides a method for preparing a first-form composite solid electrolyte, comprising the following steps: S61: Mix the sulfide solid electrolyte, binder and the above-mentioned one-dimensional solid electrolyte to obtain a solid electrolyte mixture.

[0123] Sulfide solid electrolytes refer to sulfide compounds (such as Li7P3S) that exhibit ionic conductivity. 11 The mass percentage of the binder is 80-95%, preferably 93%; the binder is preferably PTFE, with a mass percentage of 0.3%-8%, preferably 2%; the mass percentage of the one-dimensional solid electrolyte is 2%-10%, preferably 5%.

[0124] In one specific embodiment, 93 wt% Li7P3S was used. 11 (Sulfide solid electrolyte, particle size 1-3μm), 2wt% PTFE (binder), 5wt% of the above one-dimensional LLZO electrolyte.

[0125] One-dimensional LLZO electrolyte and sulfide electrolyte form a "composite system". The high mechanical strength of LLZO can compensate for the brittleness of sulfide, and the synergistic effect of the two electrolytes can improve the overall ionic conductivity.

[0126] S62: The solid electrolyte mixture is subjected to differential rolling to form a composite solid electrolyte of the first form in which one-dimensional solid electrolytes are horizontally oriented.

[0127] In one specific embodiment, the same differential speed roller press as the positive and negative electrode films is used, the roller pressing temperature is set to 40-100℃, preferably 60℃, and the roller pressing pressure is set to 49000N-196000N, preferably 117600N. Through the "folding-thinning-repetition" cycle, a first-form composite solid electrolyte with a thickness of 30-100μm, preferably 50μm, and a one-dimensional solid electrolyte horizontally oriented arrangement is finally obtained.

[0128] SEM images show that LLZO fibers are horizontally oriented (order ≥85%) along the rolling direction and are uniformly dispersed in Li7P3S. 11 Between the particles, the PTFE binder forms a continuous film on the particle and fiber surfaces (ensuring structural stability).

[0129] Differential rolling causes LLZO fibers to be horizontally oriented, forming a "parallel transport network" with the sulfide electrolyte, thereby improving the ionic conductivity of the first-form composite solid electrolyte. At the same time, rolling increases the density of the first-form composite solid electrolyte (≥2.2 g / cm³), reducing ion transport resistance caused by pores.

[0130] In this embodiment, the problems of "low mechanical strength" and "poor ion transport anisotropy" in traditional sulfide solid electrolyte membranes are solved by the composite and horizontal orientation of "sulfide + one-dimensional oxide electrolyte". The overall beneficial effects are: 1. The horizontally oriented LLZO fibers enhance the mechanical strength of the sulfide solid electrolyte membrane, avoiding damage during battery assembly and cycling; 2. The synergistic transport network of LLZO and sulfide electrolyte improves the room temperature ionic conductivity of the first-form composite solid electrolyte; 3. The dry rolling process avoids the reaction between sulfide electrolyte and water / oxygen (sulfides are easily hydrolyzed), ensuring the chemical stability of the solid electrolyte membrane.

[0131] This invention also provides a first-form composite solid electrolyte, which is prepared according to the above-described method for preparing the first-form composite solid electrolyte. The core feature of this first-form composite solid electrolyte is that it comprises a composite system of a horizontally oriented one-dimensional LLZO electrolyte and a sulfide electrolyte, which is a key component in solid-state batteries for isolating the positive and negative electrodes and conducting lithium ions.

[0132] In one specific embodiment, the composite solid electrolyte of the first morphology described above was prepared using the method described above: 50 μm thick, composed of 93 wt% Li7P3S 11 It consists of 2wt% PTFE and 5wt% horizontally oriented LLZO fibers.

[0133] This first-form composite solid electrolyte, through a "composite electrolyte + horizontal orientation" design, simultaneously improves the ion conductivity, mechanical properties, and interfacial compatibility of solid-state batteries, overcoming the performance shortcomings of traditional single-electrolyte solid electrolyte membranes. The overall beneficial effects are: 1. The horizontally oriented LLZO fibers and the sulfide electrolyte form an efficient ion transport path, meeting the ion requirements of high-rate batteries; 2. The fiber-reinforced composite structure allows the first-form composite solid electrolyte to withstand the pressure during battery assembly and volume changes during cycling, improving battery safety; 3. Good interfacial compatibility with the positive / negative electrode composite membrane reduces interfacial impedance and avoids impedance growth during cycling.

[0134] Reference Figure 7 This invention also provides a method for preparing a composite solid electrolyte membrane, comprising the following steps: S71: The composite solid electrolyte of the first form described above is folded multiple times or stacked in multiple layers and compacted to obtain the composite solid electrolyte of the second form; wherein the one-dimensional solid electrolyte in each layer of the composite solid electrolyte of the first form has the same orientation.

[0135] In one specific embodiment, the first-form composite solid electrolyte of the above embodiment is taken, stacked in 30 layers along the horizontal orientation, and after the edges are aligned, it is placed in a flat hot press. The temperature is set at 80°C and the pressure at 14700 N, and the temperature is maintained for 20 min to obtain a second-form composite solid electrolyte (with no gaps between layers) with a thickness of 1.5 cm and a density of 2.3 g / cm³.

[0136] Multilayer stacking increases the vertical distribution density of LLZO fibers, and high-temperature compaction promotes the diffusion and bonding of sulfide electrolytes, ensuring smooth interlayer ion transport and avoiding the formation of interfacial resistance.

[0137] S72: Cut the composite solid electrolyte of the second form along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the composite solid electrolyte membrane.

[0138] In one specific embodiment, the second-morphology composite solid electrolyte was cut along a direction perpendicular to the LLZO fiber orientation to obtain a composite solid electrolyte membrane with a thickness of 50 μm. SEM showed that the LLZO fibers were arranged perpendicularly to the thickness direction of the composite solid electrolyte membrane (vertical order ≥90%), and the Li7P3S... 11 The particles fill the gaps between the fibers, forming continuous vertical ion transport channels.

[0139] Vertical cutting changes the ion transport direction of the composite solid electrolyte membrane from horizontal to vertical, matching the vertical ion path of "positive electrode - solid electrolyte membrane - negative electrode" in solid batteries. At the same time, vertical fibers enhance the bending resistance of the composite solid electrolyte membrane (it can withstand 180° bending).

[0140] In this embodiment, by employing "high-temperature stacking and compaction - vertical cutting," the horizontally oriented composite electrolyte in the first-form composite solid electrolyte is transformed into a vertically oriented one, solving the problem of "mismatch between ion transport direction and battery structure" in traditional solid electrolyte membranes. The overall beneficial effects are: 1. Vertically oriented composite electrolyte channels allow lithium ions to directly penetrate the solid electrolyte membrane, improving transport efficiency and significantly reducing battery internal resistance; 2. High-temperature compaction promotes the diffusion of sulfide electrolytes, enhancing interlayer bonding strength and avoiding interlayer separation during cutting and cycling; 3. Vertical fibers enhance the mechanical properties of the solid electrolyte membrane, adapting to the stacking and assembly process of solid-state batteries.

[0141] This invention also provides a composite solid electrolyte membrane, which is prepared according to the above-described method. Its core feature is that the one-dimensional LLZO electrolyte and the sulfide electrolyte are perpendicularly oriented along the thickness direction, serving as a highly efficient ion transport bridge connecting the positive and negative electrodes in a solid-state battery.

[0142] In one specific embodiment, the composite solid electrolyte membrane has a thickness of 50 μm and is composed of 93 wt% Li7P3S 11 It consists of 2wt% PTFE and 5wt% vertically oriented LLZO fibers.

[0143] This composite solid electrolyte membrane, through its vertically oriented composite electrolyte system, solves the key bottlenecks of "low ion transport efficiency" and "high interface impedance" in solid-state batteries, making it a core component for achieving high performance in full-cell batteries. The overall beneficial effects are: 1. The vertical channels shorten the lithium-ion transport distance in the composite solid electrolyte membrane (consistent with the membrane thickness), reducing transport resistance and significantly improving the battery's fast-charging capability; 2. The synergistic effect of LLZO and sulfides enhances the chemical stability of the composite solid electrolyte membrane, making it compatible with high-voltage cathode materials; 3. Alignment with the vertical channels of the positive / negative electrode composite membrane forms an integrated vertical ion network of "positive electrode - composite solid electrolyte membrane - negative electrode," maximizing the ion transport efficiency of the full-cell battery.

[0144] This invention also provides a solid-state battery, including a positive electrode, a negative electrode, and a composite solid electrolyte membrane spaced between the positive electrode and the negative electrode; the positive electrode is the positive composite electrode in the above embodiments; and / or, the negative electrode is the negative composite electrode in the above embodiments; and / or, the composite solid electrolyte membrane is the composite solid electrolyte membrane in the above embodiments.

[0145] This solid-state battery is an energy storage device that integrates a positive electrode composite plate, a negative electrode composite plate, and a composite solid electrolyte membrane. Its core feature is the construction of a full-cell-level high-speed ion transport network through a "vertically oriented one-dimensional electrolyte," which combines high energy density, fast charging performance, and safety.

[0146] In one specific embodiment, a complete system of "positive composite electrode + composite solid electrolyte membrane + negative composite electrode" is adopted: Positive electrode composite electrode: aluminum foil current collector + 150μm positive electrode composite film on both sides; Composite solid electrolyte membrane: 50μm thick; Negative electrode composite electrode: copper foil current collector + 120μm negative electrode composite film on both sides.

[0147] Assembly process: Stack 50 layers (total thickness approximately 9.5cm) in the order of "negative electrode composite sheet - composite solid electrolyte membrane - positive electrode composite sheet", and perform hot pressing. The hot pressing temperature is set to 60-150℃, preferably 100℃, and the pressure is set to 98000N-294000N, preferably 19600N. Hold for 20-60min, preferably 30min. Weld nickel-aluminum tabs (positive electrode) and nickel-copper tabs (negative electrode). Encapsulate with aluminum-plastic film (vacuum degree ≤ -0.09MPa) to obtain a soft-pack solid-state battery (size 10cm×5cm×9.5cm).

[0148] This embodiment of the solid-state battery constructs a "direct" lithium-ion transport channel from the positive to the negative electrode by integrating a vertically oriented composite component of the positive electrode, negative electrode, and solid electrolyte membrane. This solves the core pain points of existing solid-state batteries, namely "poor fast charging, short cycle life, and insufficient safety." The overall beneficial effects are: 1. The full-cell-level vertical ion network reduces lithium-ion transport resistance and supports 4C ultra-fast charging; 2. The vertically oriented one-dimensional electrolyte enhances the structural strength of each component, buffers the volume expansion of active materials, and increases the cycle life to over 1000 cycles; 3. It is free of liquid electrolyte, and the composite electrolyte (LLZO + sulfide) has high thermal stability, achieving intrinsic battery safety (no danger from needle penetration, extrusion, or high temperature); 4. The combination of high active material loading (95wt% positive electrode and 95wt% negative electrode) and efficient transport results in high energy density, meeting the high range requirements of electric vehicles and other power equipment.

[0149] To verify the performance improvement effect of the "vertically oriented one-dimensional oxide solid electrolyte" in this invention on solid-state batteries, comparative examples (existing cells of the same system) 1-5 were set up for comparison with Examples 1-5. The specific experimental design and results are as follows: I. Test Conditions Fast charging rate test: At 25℃, charge to 4.35V with a constant current, record the full charge time at different rates, and calculate the fast charging capability.

[0150] Cyclic stability test: At 25°C, charge and discharge at 1C rate for 1000 cycles, and record the capacity retention rate every 100 cycles.

[0151] Energy density test: Calculate the energy density (Wh / kg) based on the actual capacity and mass of the battery cell.

[0152] II. Experimental Results and Analysis

[0153] Improved fast charging performance: Compared with the control group, due to the disordered dispersion of particulate electrolyte, the lithium ion transport path is long and the internal resistance is high, which only supports 0.5-0.7C slow charging; while Examples 1-5 significantly shorten the lithium ion transport distance through vertically oriented one-dimensional fiber channels, and the fast charging rate is increased to 1C-4C respectively. Among them, Example 4 achieves 4C ultra-fast charging (fully charged in 15 minutes), which verifies the significant improvement of ion transport efficiency by the oriented structure.

[0154] Enhanced cycle stability: In the comparative examples, the best performing Comparative Example 4 only had a capacity retention of 71.2% after 1000 cycles, mainly due to poor interfacial contact between the particulate electrolyte and the electrode material, and the structure was prone to collapse during cycling. In Examples 1-5, the vertically oriented one-dimensional fibers formed a "mechanical skeleton" to buffer the expansion of the electrode volume and maintain interface stability. The worst performing Example 1 had a capacity retention of 81.5% after 1000 cycles, demonstrating the key role of structural stability in cycle life.

[0155] Balance between energy density and performance: Example 1 achieves an energy density of 550Wh / kg through efficient ion transport and high active material loading (positive / negative electrode main powder ratio of 95%), which is 30.9% higher than Comparative Example 1; Examples 2-5 have a slightly lower energy density due to the increased content of one-dimensional solid electrolyte and a slightly lower proportion of active material, but the fast charging and cycle performance are further optimized, achieving an on-demand balance of "energy density-fast charging-cycle" to meet the needs of different application scenarios.

[0156] IV. Conclusion This invention addresses the core pain points of existing solid-state batteries—poor fast charging, short cycle life, and low energy density—through the design of a "vertically oriented one-dimensional oxide solid electrolyte." Compared to existing technologies, under the same system, the fast charging rate is increased by 2-8 times, the cycle capacity retention rate is improved by 18.3-28.2 percentage points, and the energy density is increased by up to 30.9%, fully demonstrating the inventiveness and practicality of the technical solution.

[0157] 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 one-dimensional solid electrolyte, characterized in that, Includes the following steps: The polymer solution was mixed with the solid electrolyte precursor to obtain a mixed solution; Using a solution-blown spinning process, the mixed solution is formed into a continuous jet, and the jet is heated to evaporate the solvent in the jet, thereby obtaining a fibrous composite. The fibrous composite was calcined to obtain the one-dimensional solid electrolyte.

2. The method for preparing a one-dimensional solid electrolyte according to claim 1, characterized in that, Heating the jet to evaporate the solvent in the jet includes: The jet is heated using a gradient heating method to cause the solvent in the jet to evaporate.

3. The method for preparing a one-dimensional solid electrolyte according to claim 1, characterized in that, The process of mixing the polymer solution with the solid electrolyte precursor to obtain a mixed solution includes: The polymer solution was mixed with a solid electrolyte precursor and ball-milled to obtain a uniformly dispersed mixed solution.

4. The method for preparing a one-dimensional solid electrolyte according to claim 1, characterized in that, The calcination treatment of the fibrous composite to obtain the one-dimensional solid electrolyte includes: The fibrous composite is heated at a first temperature to remove the polymer from the fibrous composite. The fibrous composite with removed polymer was crystallized using a second temperature to obtain the one-dimensional solid electrolyte.

5. A one-dimensional solid electrolyte, characterized in that, The one-dimensional solid electrolyte is prepared by the method for preparing one-dimensional solid electrolyte according to any one of claims 1-4.

6. A method for preparing a positive electrode film, characterized in that, Includes the following steps: The positive electrode powder, conductive agent, binder and the one-dimensional solid electrolyte as described in claim 5 are mixed to obtain a positive electrode mixture; The positive electrode mixture is subjected to differential rolling to form a one-dimensional solid electrolyte horizontally oriented positive electrode film.

7. A method for preparing a positive electrode composite film, characterized in that, Includes the following steps: The positive electrode film prepared as described in claim 6 is folded multiple times or stacked in multiple layers and compacted to obtain a positive electrode film block; wherein the one-dimensional solid electrolyte in each layer of the positive electrode film has the same orientation; The positive electrode film block is cut along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the positive electrode composite film.

8. A method for preparing a negative electrode film, characterized in that, Includes the following steps: The negative electrode powder, conductive agent, binder and the one-dimensional solid electrolyte as described in claim 5 are mixed to obtain a negative electrode mixture; The negative electrode mixture is subjected to differential rolling to form a one-dimensional solid electrolyte horizontally oriented negative electrode film.

9. A method for preparing a negative electrode composite film, characterized in that, Includes the following steps: The negative electrode film prepared as described in claim 8 is folded multiple times or stacked in multiple layers and compacted to obtain a negative electrode film block; wherein the one-dimensional solid electrolyte in each layer of the negative electrode film has the same orientation; The negative electrode film block is cut along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the negative electrode composite film.

10. A method for preparing a first-form composite solid electrolyte, characterized in that, Includes the following steps: A solid electrolyte mixture is obtained by mixing a sulfide solid electrolyte, a binder, and the one-dimensional solid electrolyte as described in claim 5. The solid electrolyte mixture is subjected to differential rolling to form a composite solid electrolyte of the first form in which one-dimensional solid electrolytes are horizontally oriented.

11. A method for preparing a composite solid electrolyte membrane, characterized in that, Includes the following steps: The composite solid electrolyte of the first form prepared as described in claim 10 is folded multiple times or stacked in multiple layers and compacted to obtain the composite solid electrolyte of the second form; wherein the one-dimensional solid electrolyte in each layer of the composite solid electrolyte of the first form has the same orientation. The composite solid electrolyte of the second form is cut along a direction perpendicular to the orientation of the one-dimensional solid electrolyte to obtain the composite solid electrolyte membrane.

12. A solid-state battery, characterized in that, It includes a positive electrode, a negative electrode, and a solid electrolyte membrane spaced between the positive and negative electrode. The positive electrode sheet is a positive electrode composite sheet in which the positive electrode composite film prepared as described in claim 7 is attached to both sides of the positive electrode current collector; and / or, The negative electrode sheet is a negative electrode composite sheet in which the negative electrode composite film prepared as described in claim 9 is attached to both sides of the negative electrode current collector; and / or, The solid electrolyte membrane is the composite solid electrolyte membrane prepared as described in claim 11.

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