Solid electrolyte, preparation method thereof and solid-state battery

Abstract

The invention provides a solid electrolyte, a preparation method thereof and a solid-state battery. The solid electrolyte comprises a plurality of layers of inorganic ion conductor films and a plurality of layers of polymer films which are laminated, and the inorganic ion conductor films and the polymer films are alternately arranged; the component of the inorganic ion conductor film is a one-dimensional inorganic ion conductor, the one-dimensional inorganic ion conductor is arranged in a preferred orientation mode, and the axial direction of the one-dimensional inorganic ion conductor is parallel to the plane where the inorganic ion conductor film is located; the thickness direction of the solid electrolyte is perpendicular to the stacking direction of the inorganic ion conductor film and the polymer film. The solid electrolyte has high ionic conductivity and high mechanical flexibility at the same time.

Description

Technical Field

[0001] This invention belongs to the field of solid-state battery technology, and relates to a solid electrolyte, its preparation method, and a solid-state battery. Background Technology

[0002] Solid electrolytes are the core materials that replace traditional liquid electrolytes and achieve high energy density and high safety batteries. They are widely used in electric vehicles, energy storage power stations and wearable electronics.

[0003] Currently, mainstream solid-state electrolyte systems include oxide ceramics (such as lithium lanthanum zirconium oxide (LLZO)), sulfide glass-ceramics (such as lithium thiophosphate (LPS) and Li-Ge-PS ceramics (LGPS)), and polymer electrolytes. Among them, sulfide glass-ceramics have the advantage of achieving a lithium-ion conductivity of up to 10 mS / cm at room temperature. -1 While attracting considerable attention, polymer electrolytes exhibit high mechanical brittleness and sensitivity to moisture, making large-area film formation difficult. Polymer electrolytes (such as polyethylene oxide (PEO) and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP)) possess excellent flexibility and interfacial compatibility, but their room-temperature ionic conductivity is only 10 Ω·cm. -5 ~10 -4 S cm -1 This falls far short of meeting high-power requirements. More importantly, none of the aforementioned solid-state electrolyte systems can simultaneously achieve both mechanical flexibility and high ionic conductivity. Composite electrolytes combining inorganic materials (such as oxide ceramics and sulfide glass ceramics) with polymers aim to combine the advantages of both, but face a trade-off between conductivity and flexibility. With low inorganic material content, the poor connectivity between inorganic materials in the polymer matrix limits the room-temperature ionic conductivity (σRT) to 1.0 mS / cm. -1 The following points are relevant: High inorganic material content can improve conductivity, but it increases the difficulty of film formation. Furthermore, the simple filling of polymer phases with a large number of inorganic material particles can easily lead to agglomeration, thereby disrupting the continuity of fast conductive paths.

[0004] For example, Chinese invention patent CN112652819B uses a single mixed-phase system. Increasing the proportion of inorganic phase to improve conductivity significantly reduces the membrane's flexibility and toughness, making it prone to cracking during battery assembly or cycling. While Chinese invention patent application CN112701357A uses high-acceleration vibration to orient lithium salt fibers perpendicular to the membrane surface, shortening the ion transport path, the fibers are randomly dispersed in a single polymer matrix, lacking stable bridging between adjacent fibers and making it difficult to form a continuous conductive path across the entire electrolyte thickness. In Chinese invention patent application CN119518082A, the fiber-filled polymer interface is "irregular"—the polymer uniformly coats the fiber surface without forming a targeted interface optimization layer. In this single composite structure, the interfacial bonding between the fiber and polymer relies on physical wetting, easily leading to interface defects (such as micropores and interfacial charge accumulation), resulting in high interfacial impedance.

[0005] In summary, existing technologies have consistently failed to simultaneously achieve both high ionic conductivity and high mechanical flexibility within the same solid electrolyte system, severely limiting the energy density, power density, and cycle life of solid-state batteries, thus becoming a key bottleneck for the large-scale commercialization of solid-state batteries. Summary of the Invention

[0006] To address the problem that solid electrolytes in the prior art cannot simultaneously achieve high ionic conductivity and high mechanical flexibility, this invention provides a solid electrolyte, its preparation method, and a solid battery.

[0007] This invention is achieved through the following technical solution: In a first aspect, the present invention provides a solid electrolyte comprising a multilayer inorganic ion conductor membrane and a multilayer polymer membrane stacked together, wherein the inorganic ion conductor membrane and the polymer membrane are alternately arranged; the inorganic ion conductor membrane is composed of a one-dimensional inorganic ion conductor, the one-dimensional inorganic ion conductor is preferably oriented and the axial direction of the one-dimensional inorganic ion conductor is parallel to the plane of the inorganic ion conductor membrane; the thickness direction of the solid electrolyte is perpendicular to the stacking direction of the inorganic ion conductor membrane and the polymer membrane.

[0008] Preferably, the one-dimensional inorganic ionic conductor is Li3N, Li2S-P2S5, or Li 0.33 La 0.56 TiO3, Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Li7P3S 11 Li 10 GeP2S 12 Lithium and phosphorus co-doped hydroxyapatite, Na3PS4, Na3Zr2Si2PO12 K3SbS4, K2ZnCl4, CaTiO3, Ca3(PO4)2, Mg3(PO4)2, MgMoO4, ZnMoO4, Zn3(PO4)2, Al2O3, AlPO4, lithium cobalt nickel iron manganese oxides, sodium cobalt nickel iron manganese sulfides, potassium cobalt nickel iron manganese phosphates, calcium magnesium aluminum zinc copper oxyfluorides, magnesium cobalt nickel iron manganese sulfides, zinc cobalt nickel iron manganese phosphates or aluminum cobalt nickel iron manganese oxides.

[0009] Preferably, the polymer in the polymer film is one or more selected from polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polypropylene carbonate-polyethylene oxide, polyvinyl carbonate, polyacrylic acid, polytetrahydrofuran, polybutadiene, and polyethylene glycol.

[0010] Preferably, based on the total mass of the solid electrolyte as 100%, the mass fraction of the inorganic ion conductor is 40%~45%, and the mass fraction of the polymer membrane is 55%~60%.

[0011] Preferably, the inorganic ion conductor film has a thickness of 10-20 μm, and the polymer film has a thickness of 20-30 μm.

[0012] Preferably, the polymer membrane contains a dissociated inorganic metal salt and an inorganic ionic conductor; the inorganic ionic conductor is the same as the inorganic ionic conductor in the inorganic ionic conductor membrane; and the dissociated inorganic metal salt and the inorganic ionic conductor have the same metal cation.

[0013] Furthermore, the dissociated inorganic metal salt is one of lithium salt, sodium salt, potassium salt, calcium salt, magnesium salt, zinc salt, and aluminum salt.

[0014] Secondly, the present invention provides a method for preparing the solid electrolyte, which is one of the following methods: Method 1: Prepare multiple polymer films and multiple inorganic ion conductor films separately, wherein the one-dimensional inorganic ion conductors in the inorganic ion conductor films are preferentially oriented; assemble the polymer films and inorganic ion conductor films together by stacking and cold pressing or rolling to obtain a solid electrolyte of a predetermined thickness; Method 2: Prepare a polymer membrane, a polymer slurry, and an inorganic ionic conductor dispersion, respectively; coat the polymer membrane with the inorganic ionic conductor dispersion and dry to form an inorganic ionic conductor membrane. During the coating and drying stages, an external field is used to preferentially align the one-dimensional inorganic ionic conductors; then coat the polymer slurry and dry to form a polymer membrane; repeat the coating and drying process of the inorganic ionic conductor dispersion and polymer slurry alternately until a solid electrolyte of a predetermined thickness is obtained. Method 3: Prepare polymer slurry and inorganic ionic conductor dispersion separately; inject the polymer slurry and inorganic ionic conductor dispersion into different inlets of the microfluidic chip. The polymer slurry and inorganic ionic conductor dispersion form a parallel fluid layer in the main channel by utilizing laminar flow characteristics. The one-dimensional inorganic ionic conductor is preferentially oriented and aligned by an external field. Subsequently, the polymer slurry and inorganic ionic conductor dispersion are solidified during the flow process by ultraviolet light, heat or chemical means to obtain a solid electrolyte of a predetermined thickness.

[0015] Thirdly, the present invention provides a solid-state battery, comprising a positive electrode, a negative electrode, and a solid electrolyte as described above located between the positive electrode and the negative electrode, wherein the axial direction of the one-dimensional inorganic ion conductor is perpendicular to both the plane containing the positive electrode and the plane containing the negative electrode.

[0016] Preferably, the solid-state battery is a lithium-ion solid-state battery, a sodium-ion solid-state battery, a potassium-ion solid-state battery, a calcium-ion solid-state battery, a zinc-ion solid-state battery, a magnesium-ion solid-state battery, or an aluminum-ion solid-state battery.

[0017] Compared with the prior art, the present invention has the following beneficial effects: The solid electrolyte of this invention employs a synergistic design of "layered structure + preferred orientation." The core lies in achieving precise control of the one-dimensional inorganic ion conductor through preferred orientation, while simultaneously forming a layered structure with a polymer film. This addresses the pain point of traditional composite electrolytes where "high ionic conductivity and flexibility are difficult to achieve simultaneously." The specific design logic and performance advantages are as follows: The one-dimensional inorganic ion conductor possesses intrinsically anisotropic ion channels. Through crystal orientation control, the inorganic ion conductors are arranged in a preferred orientation, thereby forming continuous and rapid ion channels between them. Simultaneously, the polymer acts as a deformable support framework to maintain these continuous ion channels, giving the solid electrolyte excellent flexibility. This invention, through its layered design, allows the polymer film and inorganic ion conductor film to each perform their respective functions, achieving a synergy between "high ionic conductivity" and "flexibility." Therefore, the solid electrolyte of this invention exhibits high room temperature ionic conductivity and good flexibility, which is beneficial for improving the charge-discharge performance and cycle stability of solid-state batteries. This invention also adjusts the type of inorganic phase (e.g., LLZO for lithium ions, NASICON for sodium ions, and vanadium-based oxides for zinc ions) to match different charge carriers (Li... + / Na + / K + / Zn 2+The migration size and kinetics requirements of (etc.) do not require reconstruction of the overall structure; the polymer film in the layer only serves as flexible support and interface stability, and does not directly participate in ion conduction. It can be quickly adapted to different battery systems by changing lithium salts / sodium salts / zinc salts that are suitable for the corresponding ions. Unlike existing technologies, it does not rely on a single polymer-inorganic composite system that is strongly matched with lithium ions. Therefore, this invention is applicable to lithium-ion solid-state batteries, sodium-ion solid-state batteries, potassium-ion solid-state batteries, calcium-ion solid-state batteries, zinc-ion solid-state batteries, magnesium-ion solid-state batteries, and aluminum-ion solid-state batteries, and has higher versatility.

[0018] The solid electrolyte preparation method of the present invention can be achieved by any of the following methods: stacking, spraying, rolling, scraping, and microfluidic laminar flow. The process is simple, has a high yield, and is cost-controllable. It does not require high-end equipment and is suitable for large-scale industrial production. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart of the preparation method for Example 1.

[0021] Figure 2 This is a scanning electron microscope image of the surface of the solid electrolyte prepared in Example 1.

[0022] Figure 3 This is a cross-sectional scanning electron microscope image of the solid electrolyte prepared in Example 1.

[0023] Figure 4 The ionic conductivity diagrams at room temperature for the solid electrolytes prepared in Examples 1, 2, 3, 4, 5, 6, 7, and 8 are shown.

[0024] Figure 5 The critical current density diagram is shown for the solid electrolyte prepared in Example 1.

[0025] Figure 6 The first charge-discharge curves of the solid-state batteries corresponding to the solid-state electrolytes of Examples 1, 2, 3, 4, 5, 6, and 7 are shown.

[0026] Figure 7 The graph shows the full-cell cycle performance of the solid electrolytes prepared in Example 1 and Comparative Examples 1, 2, and 3. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0028] It should be noted that the process equipment or apparatus not specifically mentioned in the following embodiments are all conventional equipment or apparatus in the art.

[0029] It should be noted that the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not intended to limit the order of the method steps or define the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0030] The solid electrolyte of this invention comprises multiple layers of inorganic ion-conducting membranes and multiple layers of polymer membranes stacked together, wherein the inorganic ion-conducting membranes and polymer membranes are alternately arranged. The inorganic ion-conducting membranes are composed of one-dimensional inorganic ion conductors, which are preferentially oriented and their axial direction is parallel to the plane of the inorganic ion-conducting membrane. The thickness direction of the solid electrolyte is perpendicular to the stacking direction of the inorganic ion-conducting membranes and polymer membranes. The preferred orientation of the one-dimensional inorganic ion conductors means that the axial directions of most of the inorganic ion conductors within the membrane are oriented in the same direction.

[0031] In this scheme, the axial direction of the one-dimensional inorganic ion conductor is the same and parallel to the plane of the inorganic ion conductor film. When applied to solid-state batteries, both the inorganic ion conductor film and the polymer film are arranged perpendicular to the positive and negative electrodes, so that the axial direction of the one-dimensional inorganic ion conductor is perpendicular to the positive and negative electrodes, and a continuous ion channel is formed between the one-dimensional inorganic ion conductors along the direction from the positive to the negative electrode. The solid electrolyte of the present invention adds a one-dimensional inorganic ion conductor, which has intrinsically anisotropic ion channels. Through crystal orientation control, the inorganic ion conductors are arranged in a preferred orientation, thereby forming a continuous and rapid ion channel between the inorganic ion conductors.

[0032] Specifically, the morphology of the one-dimensional inorganic ionic conductor can be nanowires or nanorods.

[0033] In some preferred embodiments of the present invention, the one-dimensional inorganic ionic conductor can be Li3N, Li2S-P2S5, or Li 0.33 La 0.56 TiO3 (LLTO), Li 1.3 Al 0.3 Ti 1.7 (PO4)3 (LATP), Li7P3S 11 Li 10 GeP2S 12 Lithium and phosphorus co-doped hydroxyapatite, Na3PS4, Na3Zr2Si2PO 12 (NASICON), K3SbS4, K2ZnCl4, CaTiO3, Ca3(PO4)2, Mg3(PO4)2, MgMoO4, ZnMoO4, Zn3(PO4)2, Al2O3, AlPO4, lithium cobalt nickel iron manganese oxides, sodium cobalt nickel iron manganese sulfides, potassium cobalt nickel iron manganese phosphates, calcium magnesium aluminum zinc copper oxyfluorides, magnesium cobalt nickel iron manganese sulfides, zinc cobalt nickel iron manganese phosphates or aluminum cobalt nickel iron manganese oxides.

[0034] As a further preferred embodiment, the one-dimensional inorganic ionic conductor is LLTO.

[0035] In some preferred embodiments of the present invention, the polymer in the polymer membrane is one or more selected from PEO, polyacrylonitrile (PAN), polyvinylidene fluoride (PVDF), PVDF-HFP, polypropylene carbonate-ethylene oxide (PPC), polyethylene carbonate (PEC), polyacrylic acid (PAA), polytetrahydrofuran (PTHF), polybutadiene (PB), and polyethylene glycol (PEG). More preferably, a combination of polyethylene oxide and polyvinylidene fluoride-hexafluoropropylene copolymer (PEO / PVDF-HFP) is used. The polymer used in the present invention has a certain degree of viscosity, which can effectively immobilize inorganic ionic conductors and improve the stability of the solid electrolyte.

[0036] In some preferred embodiments of the present invention, based on the total mass of the solid electrolyte being 100%, the mass fraction of the inorganic ion conductor is 10% to 90%, and the mass fraction of the polymer membrane is 10% to 90%; more preferably, the mass fraction of the inorganic ion conductor is 40% to 45%, and the mass fraction of the polymer membrane is 55% to 60%. The present invention achieves high ionic conductivity in the solid electrolyte by preferentially aligning the inorganic ion conductors, allowing ions to be transported along a rapid ion pathway.

[0037] In some preferred embodiments of the present invention, the thickness of the inorganic ion conductor film is 10~20μm, and the thickness of the polymer film is 20~30μm.

[0038] In some preferred embodiments of the present invention, the thickness of the solid electrolyte is 50~300μm, for example, it can be 200μm.

[0039] In some preferred embodiments of the present invention, the polymer membrane contains a dissociated inorganic metal salt and an inorganic ionic conductor. The polymer membrane contains a dissociated inorganic metal salt and an inorganic ionic conductor; the inorganic ionic conductor is the same as the inorganic ionic conductor in the inorganic ionic conductor membrane; the dissociated inorganic metal salt and the inorganic ionic conductor have the same metal cation, selected from one of Li, Na, K, Ca, Mg, Zn, or Al.

[0040] The dissociative inorganic metal salt is a soluble salt composed of metal cations and inorganic anions, such as LiPF6, LiTFSI, and LiBF4. It can dissociate into freely moving metal cations in the polymer film, which are mainly used to provide ion conduction carriers. The inorganic ion conductor itself can realize the directional migration of ions.

[0041] The dissociable inorganic metal salt primarily serves to provide an ion source, reduce polymer crystallinity, and promote dissociation in the polymer membrane. Furthermore, the inorganic ion conductor exhibits anisotropic conductivity, thereby accelerating ion transport and improving mechanical properties within the polymer membrane, in addition to the aforementioned functions.

[0042] The dissociated inorganic metal salt is one of lithium, sodium, potassium, calcium, magnesium, zinc, and aluminum salts. Specifically, the lithium salt is selected from LiCl, Li₂CO₃, LiPF₆, LiTFSI, LiClO₄, and LiBF₄; the sodium salt is selected from NaCl, Na₂CO₃, NaPF₆, NaTFSI, NaClO₄, and NaBF₄; the potassium salt is selected from KCl, K₂CO₃, KPF₆, KTFSI, KClO₄, and KBF₄; the calcium salt is selected from CaCl₄, CaCO₃, Ca(NO₃)₂, Ca(TFSI)₂, Ca(ClO₄)₂, and Ca(BF₄)₂; and the magnesium salt... The zinc salt is selected from MgCl2, MgCO3, MgSO4·7H2O, Mg(TFSI)2, Mg(ClO4)2, and Mg(BF4)2; the aluminum salt is selected from AlCl3, Al(NO3)3·9H2O, Al2(SO4)3·18H2O, Al(TFSI)3, Al(ClO4)3, and Al(BF4)3. Preferably, the dissociated inorganic metal salt is LiTFSI.

[0043] The preferred mass ratio of polymer to dissociated inorganic metal salt in the polymer membrane is (0.5~5):1, for example, 2:1. The preferred mass ratio of polymer to inorganic ionic conductor in the polymer membrane is 100:3. The addition of dissociable inorganic metal salts to the polymer membrane of this invention can provide an ion source, reduce polymer crystallinity, and promote dissociation; the addition of inorganic ion conductors can accelerate ion transport speed and improve mechanical properties.

[0044] The solid electrolyte described in this invention can be prepared by passive composite (stacking, rolling, spraying, scraping) or active composite (microfluidic laminar flow) of inorganic ionic conductors and polymers.

[0045] Specifically, the method for preparing the solid electrolyte of the present invention is one of the following methods: Method 1 (applicable to stacking and cold pressing, roll pressing): Prepare multiple polymer films and multiple inorganic ion conductor films respectively, wherein the one-dimensional inorganic ion conductors in the inorganic ion conductor films are preferentially oriented along the direction parallel to the film; assemble the polymer films and inorganic ion conductor films together by stacking and cold pressing or roll pressing to obtain a solid electrolyte of a predetermined thickness; Method 2 (applicable to spraying and scraping): Prepare a polymer film, a polymer slurry, and an inorganic ionic conductor dispersion, respectively; coat the polymer film with the inorganic ionic conductor dispersion and dry to form an inorganic ionic conductor film. During the coating and drying stages, an external field is used to preferentially align the one-dimensional inorganic ionic conductors along the direction parallel to the film; then coat with the polymer slurry and dry to form a polymer film; repeat the coating and drying process of the inorganic ionic conductor dispersion and polymer slurry alternately until a solid electrolyte of a predetermined thickness is obtained; Method 3 (applicable to microfluidic laminar flow co-assembly): Prepare polymer slurry and inorganic ionic conductor dispersion separately; inject the polymer slurry and inorganic ionic conductor dispersion into different inlets of the microfluidic chip respectively. The polymer slurry and inorganic ionic conductor dispersion form a stable parallel fluid layer in the main channel by utilizing laminar flow characteristics. By introducing external fields (such as electric field, magnetic field, shear force field), the one-dimensional inorganic ionic conductor is preferentially oriented and aligned along the direction parallel to the film. Subsequently, the polymer slurry and inorganic ionic conductor dispersion are solidified during the flow process by ultraviolet light, heat or chemical means to obtain a solid electrolyte of a predetermined thickness.

[0046] In one specific embodiment of the present invention, the solid electrolyte is prepared by a stacking and cold pressing method, comprising: (1) Disperse the polymer in a solvent to obtain a polymer slurry; coat the polymer slurry onto a substrate and dry it to obtain a polymer film; (2) Disperse the inorganic ionic conductor in water to obtain an inorganic ionic conductor dispersion. Then, perform orientation treatment to allow the inorganic ionic conductor to be oriented in a preferred manner. After drying, obtain an inorganic ionic conductor membrane.

[0047] (3) The polymer membrane and the inorganic ion conductor membrane are bonded together and pressure is applied; the polymer membrane and the inorganic ion conductor membrane are repeatedly stacked alternately until the preset thickness is reached, and then cold-pressed to obtain a solid electrolyte.

[0048] In this method, the cold pressing pressure is 0.1~200MPa, more preferably 10~30MPa.

[0049] In one specific embodiment of the present invention, the solid electrolyte is prepared by a rolling process, comprising: (1) Disperse the polymer in a solvent to obtain a polymer slurry; coat the polymer slurry onto a substrate and dry it to obtain a polymer film; (2) Disperse the inorganic ionic conductor in water to obtain an inorganic ionic conductor dispersion. Then, perform orientation treatment to make the inorganic ionic conductors preferentially oriented and arrange themselves. After drying, an inorganic ionic conductor membrane is obtained. (3) The polymer membrane and the inorganic ion conductor membrane are combined by rolling; the polymer membrane and the inorganic ion conductor membrane are repeatedly rolled alternately until the preset thickness is reached, and then cold-pressed to obtain a solid electrolyte.

[0050] In one specific embodiment of the present invention, the solid electrolyte is prepared by spraying or scraping, comprising: (1) Disperse the polymer in a solvent to obtain a polymer slurry; coat the polymer slurry onto a substrate and dry it to obtain a polymer film; (2) Disperse the inorganic ionic conductor in water to obtain an inorganic ionic conductor dispersion; (3) Lay the polymer membrane flat on the hot table, spray or scrape the inorganic ion conductor dispersion onto the polymer membrane, use an external field to promote the inorganic ion conductors to preferentially align along the direction parallel to the membrane, dry after orientation to form an inorganic ion conductor membrane; spray or scrape the polymer slurry onto the inorganic ion conductor membrane again, dry to form a polymer membrane; repeat the spraying or scraping process of inorganic ion conductor dispersion and polymer slurry alternately until the preset thickness is reached, cold press to compact, and obtain a solid electrolyte.

[0051] In one specific embodiment of the present invention, the solid electrolyte is prepared by a microfluidic laminar co-assembly method, comprising: (1) Disperse the polymer in a solvent to obtain a polymer slurry; (2) Disperse the inorganic ionic conductor in water to obtain an inorganic ionic conductor dispersion; (3) Inject the polymer slurry and the inorganic ionic conductor dispersion into the two independent feed inlets of the microfluidic chip respectively. By adjusting the fluid flow rate of the two feed inlets (the flow rate ratio is (1~5):1), the polymer slurry and the inorganic ionic conductor dispersion form a stable parallel fluid layer in the main channel of the microfluidic chip, and there is no obvious mixing between the two fluid layers.

[0052] (4) Using an external field to induce inorganic ion conductors to preferentially align along the direction parallel to the membrane. In the middle section of the main channel, the parallel fluid layer is synchronously solidified by ultraviolet light irradiation (power 50~100mW / cm², time 30s~2min), infrared heating at 60~80℃, or chemical crosslinking agent injection; the preset thickness is achieved by adjusting the fluid flow rate and the collection time at the microfluidic chip outlet.

[0053] In the above methods, the polymer slurry may also contain dissociated inorganic metal salts and inorganic ionic conductors as described above. The preferred mass ratio of polymer to dissociated inorganic metal salt is (0.5~5):1, for example, it can be 2:1. The preferred mass ratio of polymer to inorganic ionic conductor is 100:3.

[0054] In the above methods, the solvent can be one or more of N-methylpyrrolidone (NMP), N,N-dimethylformamide (DMF), acetonitrile, methanol, ethanol, isopropanol, dimethyl sulfoxide (DMSO), ethylene glycol, and acetone. More preferably, the solvent is NMP or DMF.

[0055] In each of the above methods, in step (1), the polymer is dispersed in a solvent at a dispersion temperature of 30-80°C and a dispersion time of 6-24h; more preferably, the dispersion temperature and time are 60°C and the stirring time is 12h.

[0056] In all the above methods, the drying temperature is 40~80℃ and the drying time is 6~24h. More preferably, the drying temperature is 60℃ and the drying time is 12h.

[0057] The solid electrolyte provided by this invention has a continuous ion conduction path inside, which can accelerate ion transport and improve its stability when used in solid-state batteries, thereby improving the charge-discharge stability and cycle life of solid-state batteries.

[0058] Specifically, the solid-state battery based on the solid electrolyte of the present invention includes a positive electrode, a negative electrode, and a solid electrolyte located between the positive electrode and the negative electrode, wherein the axis of the one-dimensional inorganic ion conductor is perpendicular to both the plane of the positive electrode and the plane of the negative electrode.

[0059] The solid-state battery of the present invention can be a lithium-ion solid-state battery, a sodium-ion solid-state battery, a potassium-ion solid-state battery, a calcium-ion solid-state battery, a zinc-ion solid-state battery, a magnesium-ion solid-state battery, or an aluminum-ion solid-state battery. The solid-state battery can be used in mobile electronic communication devices, electric vehicles, energy storage batteries, power batteries, energy storage power stations, etc.

[0060] Example 1 (Stacking) refer to Figure 1 The preparation method of the solid electrolyte in this embodiment includes the following steps: (1) Weigh 1.2g of PEO, 0.4g of PVDF-HFP, 0.8g of LiTFSI and 0.05g of LLTO in a glove box, add them to 20mL of DMF, and stir at 60℃ for 12h to obtain a uniform polymer slurry.

[0061] (2) The polymer slurry obtained in step (1) is uniformly coated onto a polytetrafluoroethylene plate. The solvent DMF is removed by vacuum drying to obtain a polymer film (PEO / PVDF-HFP film) with a thickness of approximately 20 μm. Several PEO / PVDF-HFP films are prepared in the same manner.

[0062] (3) Disperse the LLTO sample in deionized water, and use ultrasonic treatment with a power of 100W for 30 minutes to peel it off. Then, centrifuge at 2000rpm for 5 minutes, collect the supernatant, and obtain the LLTO nanowire dispersion.

[0063] (4) The LLTO nanowire dispersion obtained in step (3) was subjected to vacuum filtration. A vacuum filtration device with a core diameter of 10 cm was used, equipped with an aqueous microporous filter membrane with a pore size of 0.45 μm and a diameter of 11 cm. The filtration was carried out at a vacuum of 0.09 MPa for 30 min until no obvious moisture residue was left in the resulting film. Then, it was placed in a vacuum drying oven at 60 °C and dried for 12 h to obtain an inorganic ion conductor membrane. The thickness of the inorganic ion conductor membrane was approximately 20 μm and the area was 60 cm². 2 The mass is approximately 0.25 g. In this membrane, LLTO nanowires oriented inwards account for more than 70% of the total number of nanowires. Several inorganic ion-conducting membranes were prepared using the same method.

[0064] (5) The PEO / PVDF-HFP membrane prepared in step (2) and the LLTO inorganic ion conductor membrane prepared in step (4) are tightly bonded under a pressure of 20 MPa. By alternately stacking the two membrane materials to a preset thickness, a layered composite block with periodically alternating inorganic / polymer structures is constructed. Subsequently, the block is cut into four equal parts and cold-pressed. The above process is repeated twice, and after three rounds of stacking, a cuboid structure with a thickness of 1 cm is finally formed. It is then placed under vacuum drying conditions at 60℃ for 12 h to complete the preparation of the composite block.

[0065] (6) The composite block obtained in step (5) is cut into the substrate at -20°C with an angle of 30° (the angle between the stacking direction of the inorganic ion conductor film and the polymer film) to obtain a solid electrolyte with a thickness of 200 μm.

[0066] (7) The solid electrolyte obtained in step (6) is cut into round pieces with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button battery is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0067] The solid electrolyte obtained in this embodiment includes a multilayer LLTO film and a multilayer PEO / PVDF-HFP film stacked together, wherein the LLTO film and the PEO / PVDF-HFP film are alternately arranged; LiTFSI and LLTO are distributed in the PEO / PVDF-HFP film, and the LLTO nanowires in the LLTO film are preferentially oriented and their axial direction is parallel to the plane of the LLTO film; the thickness direction of the solid electrolyte is perpendicular to the stacking direction of the LLTO film and the PEO / PVDF-HFP film.

[0068] Example 2 (Spraying) (1) Weigh 1.2g of PEO, 0.4g of PVDF-HFP, 0.8g of LiTFSI and 0.05g of LLTO in a glove box, add them to 20mL of DMF, and stir at 60℃ for 12h to obtain a uniform polymer slurry.

[0069] (2) The polymer slurry obtained in step (1) is uniformly coated onto a polytetrafluoroethylene plate. The solvent DMF is removed by vacuum drying to obtain a polymer film (PEO / PVDF-HFP film) with a thickness of approximately 20 μm. Several PEO / PVDF-HFP films are prepared in the same manner.

[0070] (3) Disperse the LLTO sample in deionized water, and use ultrasonic treatment with a power of 100W for 30 minutes to peel it off. Then, centrifuge at 2000rpm for 5 minutes, collect the supernatant, and obtain the LLTO nanowire dispersion.

[0071] (4) Spread the PEO / PVDF-HFP membrane obtained in step (2) on a hot plate at 60°C; load the LLTO nanowire dispersion obtained in step (3) into an ultrasonic nozzle (flow rate 1 mL / min). -1 The carrier gas (N2, 0.3 MPa) is used in the ultrasonic nozzle. The gas path channel adopts an "inclined jet structure" so that the N2 carrier gas (0.3 MPa) does not impact the substrate vertically, but is ejected at an angle of 45° to the film surface. After 20 unidirectional scans, flash evaporation is performed at 60°C for 30 seconds after each scan. The nanowires are initially flattened under the action of horizontal shear force. After the solvent evaporates, their parallel posture is fixed, resulting in an inorganic ion conductor film with a thickness of 20 μm. Subsequently, the polymer slurry from step (1) is sprayed again on the inorganic ion conductor film and vacuum dried at 60°C for 1 hour to form a 20 μm polymer film. The process of alternately spraying the dispersion and polymer slurry is repeated until the total thickness reaches 1 cm. The film is then vacuum dried at 60°C for 12 hours and cold-pressed to form a dense film.

[0072] (5) The block obtained in step (4) is cut into the solid electrolyte with a thickness of 200 μm at -20°C using a slicer at an angle of 30° (the angle between the stacking direction of the inorganic ion conductor film and the polymer film).

[0073] (6) The solid electrolyte obtained in step (5) is punched into a circular piece with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button cell is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0074] The solid electrolyte structure obtained in this embodiment is the same as that in Embodiment 1.

[0075] Example 3 (Volume) (1)~(4) are the same as in Example 1.

[0076] (5) The PEO / PVDF-HFP membrane from step (2) and the inorganic ion conductor membrane from step (4) are respectively wound onto an unwinding shaft; and passed through a 60°C hot roller (linear pressure 5N cm). -1 Linear velocity 0.5 m / min -1 The layers are continuously laminated to form a composite tape consisting of a polymer film and an inorganic ion conductor film. After winding, the tape is unwound and laminated again to achieve a total thickness of 1 cm. Finally, it is vacuum dried at 60°C for 12 hours and then cold-pressed to achieve density.

[0077] (6) The block obtained in step (5) is cut into the solid electrolyte with a thickness of 200 μm at -20°C using a slicer at an angle of 30° (the angle between the stacking direction of the inorganic ion conductor film and the polymer film).

[0078] (7) The solid electrolyte obtained in step (6) is cut into round pieces with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button battery is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0079] The solid electrolyte structure obtained in this embodiment is the same as that in Embodiment 1.

[0080] Example 4 (Microfluidic Laminar Control) (1) Weigh 1.2g of PEO, 0.4g of PVDF-HFP, 0.8g of LiTFSI and 0.05g of LLTO in a glove box, add them to 20mL of DMF, and stir at 60℃ for 12h to obtain a uniform polymer slurry.

[0081] (2) Disperse the LLTO sample in deionized water, and use ultrasonic treatment with a power of 100W for 30 min to peel it off. Then centrifuge at 2000 rpm for 5 min, collect the supernatant, and obtain the LLTO nanowire dispersion.

[0082] (3) A dual-channel coaxial microfluidic device (inner channel diameter: 0.8 mm, outer channel 1.5 mm) was adopted, equipped with a high-precision injection pump, a temperature-controlled curing platform and an online thickness monitor. The receiving substrate was a polytetrafluoroethylene (PTFE) roll material treated with plasma. The equipment parameters were set as follows: polymer slurry delivery rate 8~10 μL / min, inorganic nanowire dispersion delivery rate 6~8 μL / min, microchannel temperature 40℃, curing platform vacuum degree 0.09 MPa, temperature 60℃, and PTFE substrate transfer rate 1~2 mm / min.

[0083] (4) Start the dual-channel injection pump and inject the polymer slurry obtained in step (1) and the LLTO nanowire dispersion obtained in step (2) into the inner and outer channels of the microfluidic device, respectively. A "polymer-inorganic" coaxial laminar flow is formed at the channel outlet and continuously deposited onto the PTFE substrate. Utilize the microfluidic channel for 100~150 s... - The shear rate¹ induces LLTO nanowires to preferentially align parallel to the membrane direction. By periodically switching the fluid type of the inner and outer channels every 30 seconds using a channel switching valve, a periodic structure of alternating "inorganic ion conductor membrane-polymer membrane" is constructed, ultimately forming a cuboid structure with a thickness of 1 cm. The composite bulk is then prepared by treating it under vacuum drying conditions at 60℃ for 12 hours.

[0084] (5) Freeze the composite block obtained in step (4) at -20°C for 1 hour, and use a slicer to cut it at an angle of 30° (the angle between the stacking direction of the inorganic ion conductor membrane and the polymer membrane) to obtain a solid electrolyte with a thickness of 200 μm.

[0085] (6) The solid electrolyte obtained in step (5) is punched into a circular piece with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button cell is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0086] The solid electrolyte structure obtained in this embodiment is the same as that in Embodiment 1.

[0087] Example 5 (Two polymers) (1) Weigh 2g of PEO, 4g of PPC, 0.8g of LiTFSI and 0.05g of LLTO in a glove box, add them to 20mL of acetonitrile, and stir at 60℃ for 12h to obtain a uniform polymer slurry.

[0088] (2) The polymer slurry obtained in step (1) is uniformly coated onto a polytetrafluoroethylene plate. The solvent acetonitrile is removed by vacuum drying to obtain a polymer film (PEO / PPC film) with a thickness of approximately 20 μm. Several PEO / PPC films are prepared in the same manner.

[0089] (3) Disperse the LLTO sample in deionized water, and use ultrasonic treatment with a power of 100W for 30 minutes to peel it off. Then, centrifuge at 2000rpm for 5 minutes, collect the supernatant, and obtain the LLTO nanowire dispersion.

[0090] (4) The LLTO nanowire dispersion obtained in step (3) was subjected to vacuum filtration. A vacuum filtration device with a core diameter of 10 cm was used, equipped with an aqueous microporous filter membrane with a pore size of 0.45 μm and a diameter of 11 cm. The filtration was carried out at a vacuum of 0.09 MPa for 30 min until no obvious moisture residue was left in the resulting film. Then, it was placed in a vacuum drying oven at 60 °C and dried for 12 h to obtain an inorganic ion conductor membrane. The thickness of the inorganic ion conductor membrane was approximately 20 μm and the area was 60 cm². 2 The mass is approximately 0.25 g. In this membrane, LLTO nanowires oriented inwards account for more than 70% of the total number of nanowires. Several inorganic ion-conducting membranes were prepared using the same method.

[0091] (5) The PEO / PPC membrane prepared in step (2) and the LLTO inorganic ion conductor membrane prepared in step (4) are tightly bonded under a pressure of 20 MPa. By alternately stacking the two membrane materials to a preset thickness, a layered composite block with periodically alternating inorganic / polymer structures is constructed. Subsequently, the block is cut into four equal parts and cold-pressed. The above process is repeated twice, and after three rounds of stacking, a cuboid structure with a thickness of 1 cm is finally formed. It is then placed under vacuum drying conditions at 60℃ for 12 h to complete the preparation of the composite block.

[0092] (6) The composite block obtained in step (5) is cut into the solid electrolyte with a thickness of 200 μm at -20°C using a slicer at an angle of 30° (the angle between the stacking direction of the inorganic ion conductor film and the polymer film).

[0093] (7) The solid electrolyte obtained in step (6) is cut into round pieces with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button battery is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0094] The solid electrolyte obtained in this embodiment includes a multilayer LLTO film and a multilayer PEO / PPC film stacked together, wherein the LLTO film and the PEO / PPC film are alternately arranged; the LLTO nanowires in the LLTO film are preferentially oriented and their axial direction is parallel to the plane of the LLTO film; the PEO / PPC film contains LiTFSI and LLTO; the thickness direction of the solid electrolyte is perpendicular to the stacking direction of the LLTO film and the PEO / PPC film.

[0095] Example 6 (Low-viscosity polymer) (1) Weigh 4.8 g of PVDF-HFP, 2.4 g of LiTFSI and 0.05 g of LLTO in a glove box and add them to 20 mL of DMF. Stir at 60 °C for 12 h to obtain a uniform polymer slurry.

[0096] (2) The polymer slurry obtained in step (1) is uniformly coated onto a polytetrafluoroethylene plate. The solvent DMF is removed by vacuum drying to obtain a polymer film (PVDF-HFP film) with a thickness of approximately 20 μm. Several PVDF-HFP films are prepared in the same manner.

[0097] (3) Disperse the LLTO sample in deionized water, and use ultrasonic treatment with a power of 100W for 30 minutes to peel it off. Then, centrifuge at 2000rpm for 5 minutes, collect the supernatant, and obtain the LLTO nanowire dispersion.

[0098] (4) The LLTO nanowire dispersion obtained in step (3) was subjected to vacuum filtration. A vacuum filtration device with a core diameter of 10 cm was used, equipped with an aqueous microporous filter membrane with a pore size of 0.45 μm and a diameter of 11 cm. The filtration was carried out at a vacuum of 0.09 MPa for 30 min until no obvious moisture residue was left in the resulting film. Then, it was placed in a vacuum drying oven at 60 °C and dried for 12 h to obtain an inorganic ion conductor membrane. The thickness of the inorganic ion conductor membrane was approximately 20 μm and the area was 60 cm². 2 The mass is approximately 0.25 g. In this membrane, LLTO nanowires oriented inwards account for more than 70% of the total number of nanowires. Several inorganic ion-conducting membranes were prepared using the same method.

[0099] (5) The PVDF-HFP membrane prepared in step (2) and the LLTO inorganic ion conductor membrane prepared in step (4) are tightly bonded under a pressure of 20 MPa. By alternately stacking the two membrane materials to a preset thickness, a layered composite block with periodically alternating inorganic / polymer structures is constructed. Subsequently, the block is cut into four equal parts and cold-pressed. The above process is repeated twice, and after three rounds of stacking, a cuboid structure with a thickness of 1 cm is finally formed. It is then placed under vacuum drying conditions at 60℃ for 12 h to complete the preparation of the composite block.

[0100] (6) The composite block obtained in step (5) is cut into the solid electrolyte with a thickness of 200 μm at -20°C using a slicer at an angle of 30° (the angle between the stacking direction of the inorganic ion conductor film and the polymer film).

[0101] (7) The solid electrolyte obtained in step (6) is cut into round pieces with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button battery is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0102] The solid electrolyte obtained in this embodiment includes a multilayer LLTO film and a multilayer PVDF-HFP film stacked together, wherein the LLTO film and the PVDF-HFP film are alternately arranged; the LLTO nanowires in the LLTO film are preferentially oriented and their axial direction is parallel to the plane of the LLTO film; the PVDF-HFP film contains LiTFSI and LLTO; the thickness direction of the solid electrolyte is perpendicular to the stacking direction of the LLTO film and the PVDF-HFP film.

[0103] Example 7 (Polymer without the addition of dissociative inorganic metal salts) (1) Weigh 1.2g of PEO and 0.4g of PVDF-HFP in a glove box, add them to 20mL of DMF, and stir at 60℃ for 12h to obtain a uniform polymer slurry.

[0104] (2) The polymer slurry obtained in step (1) is uniformly coated onto a polytetrafluoroethylene plate. The solvent acetonitrile is removed by vacuum drying to obtain a polymer film (PEO / PVDF-HFP film) with a thickness of approximately 20 μm. Several PEO / PVDF-HFP films are prepared in the same manner.

[0105] (3) Disperse the LLTO sample in deionized water, and use ultrasonic treatment with a power of 100W for 30 minutes to peel it off. Then, centrifuge at 2000rpm for 5 minutes, collect the supernatant, and obtain the LLTO nanowire dispersion.

[0106] (4) The LLTO nanowire dispersion obtained in step (3) was subjected to vacuum filtration. A vacuum filtration device with a core diameter of 10 cm was used, equipped with an aqueous microporous filter membrane with a pore size of 0.45 μm and a diameter of 11 cm. The filtration was carried out at a vacuum of 0.09 MPa for 30 min until no obvious moisture residue was left in the resulting film. Then, it was placed in a vacuum drying oven at 60 °C and dried for 12 h to obtain an inorganic ion conductor membrane. The thickness of the inorganic ion conductor membrane was approximately 20 μm and the area was 60 cm². 2 The mass is approximately 0.25 g. In this membrane, LLTO nanowires oriented inwards account for more than 70% of the total number of nanowires. Several inorganic ion-conducting membranes were prepared using the same method.

[0107] (5) The PEO / PVDF-HFP membrane prepared in step (2) and the LLTO inorganic ion conductor membrane prepared in step (4) are tightly bonded under a pressure of 20 MPa. By alternately stacking the two membrane materials to a preset thickness, a layered composite block with periodically alternating inorganic / polymer structures is constructed. Subsequently, the block is cut into four equal parts and cold-pressed. The above process is repeated twice, and after three rounds of stacking, a cuboid structure with a thickness of 1 cm is finally formed. It is then placed under vacuum drying conditions at 60℃ for 12 h to complete the preparation of the composite block.

[0108] (6) The composite block obtained in step (5) is cut into the solid electrolyte with a thickness of 200 μm at -20°C using a slicer at an angle of 30° (the angle between the stacking direction of the inorganic ion conductor film and the polymer film).

[0109] (7) The solid electrolyte obtained in step (6) is cut into round pieces with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button battery is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0110] The solid electrolyte obtained in this embodiment includes a multilayer LLTO membrane and a multilayer PEO / PVDF-HFP membrane stacked together, wherein the LLTO membrane and the PEO / PVDF-HFP membrane are alternately arranged; the LLTO nanowires in the LLTO membrane are preferentially oriented and their axis is parallel to the plane of the LLTO membrane; the PEO / PVDF-HFP membrane does not contain dissociated inorganic metal salts or inorganic ionic conductors; the thickness direction of the solid electrolyte is perpendicular to the stacking direction of the LLTO membrane and the PEO / PVDF-HFP membrane.

[0111] Comparative Example 1 (non-oriented (no individual inorganic ion conductor film), with layering) (1) Weigh 1.2g of PEO, 0.4g of PVDF-HFP and 0.8g of LiTFSI in a glove box, add them to 20mL of DMF, and stir at 60℃ for 12h to obtain a uniform polymer slurry.

[0112] (2) Add the LLTO sample to the polymer slurry prepared in step (1) and stir to obtain a mixed slurry. Then cast several portions of the mixed slurry onto a polytetrafluoroethylene plate in batches. After each casting, heat to remove the solvent, and finally form a block structure with a thickness of 1 cm. Dry it under vacuum at 60°C for 12 h.

[0113] (3) The block obtained in step (2) is cut into the solid electrolyte at a 30° angle at -20° using a cryostat. The solid electrolyte has a thickness of 200 μm.

[0114] (4) The solid electrolyte obtained in step (3) is cut into round pieces with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button battery is assembled in a glove box according to the battery assembly process and then tested for electrochemical performance.

[0115] The solid electrolyte obtained in this comparative example includes a PEO / PVDF-HFP membrane, in which LLTO is distributed.

[0116] Comparative Example 2 (unoriented (no orientation inside the inorganic ion conductor film), with layering) (1) Weigh 1.2g of PEO, 0.4g of PVDF-HFP, 0.8g of LiTFSI and 0.05g of LLTO in a glove box, add them to 20mL of DMF, and stir at 60℃ for 12h to obtain a uniform polymer slurry.

[0117] (2) The polymer slurry obtained in step (1) is uniformly coated onto a polytetrafluoroethylene plate. The solvent DMF is removed by vacuum drying to obtain a polymer film (PEO / PVDF-HFP film) with a thickness of approximately 20 μm. Several PEO / PVDF-HFP films are prepared in the same manner.

[0118] (3) Disperse the LLTO sample in deionized water, and use ultrasonic treatment with a power of 100W for 30 min to peel it off. Then centrifuge at 2000 rpm for 5 min, collect the supernatant, and obtain LLTO nanosheet dispersion.

[0119] (4) The LLTO nanowire dispersion obtained in step (5) was uniformly coated onto a polytetrafluoroethylene plate and dried in a vacuum drying oven at 60°C for 12 hours to obtain a non-oriented inorganic ion conductor film. The thickness of the inorganic ion conductor film was approximately 20 μm, and the area was 60 cm². 2 The inorganic ion conductor film, with a mass of approximately 0.25 g, has unoriented nanowires inside. Several other inorganic ion conductor films were prepared using the same method.

[0120] (5) The PEO / PVDF-HFP polymer membrane prepared in step (2) and the LLTO inorganic ion conductor membrane prepared in step (4) are tightly bonded under a pressure of 20 MPa. By alternately stacking the two membrane materials to a preset thickness, a layered composite block with periodically alternating inorganic / polymer layers is constructed. Subsequently, the block is cut into four equal parts and cold-pressed. The above process is repeated twice, and after three rounds of stacking, a cuboid structure with a thickness of 1 cm is finally formed. It is then placed under vacuum drying conditions at 60℃ for 12 h to complete the preparation of the composite block.

[0121] (6) The composite block obtained in step (5) is cut into the solid electrolyte with a thickness of 200 μm at -20°C using a slicer at an angle of 30° (the angle between the stacking direction of the inorganic ion conductor film and the polymer film).

[0122] (7) The solid electrolyte obtained in step (6) is cut into round pieces with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button battery is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0123] The solid electrolyte obtained in this embodiment includes a multilayer LLTO film and a multilayer PEO / PVDF-HFP film stacked together, with the LLTO film and PEO / PVDF-HFP film alternately arranged. The PEO / PVDF-HFP film contains inorganic metal salts and inorganic ionic conductors. The thickness direction of the solid electrolyte is perpendicular to the stacking direction of the LLTO film and the PEO / PVDF-HFP film. The LLTO nanowires in the LLTO film are arranged without orientation.

[0124] Comparative Example 3 (oriented, non-periodic stratification) (1) Weigh 1.2g of PEO, 0.4g of PVDF-HFP, 0.8g of LiTFSI and 0.05g of LLTO in a glove box, add them to 20mL of DMF, and stir at 60℃ for 12h to obtain a uniform polymer slurry.

[0125] (2) The polymer slurry obtained in step (1) is uniformly coated onto a polytetrafluoroethylene plate. The solvent DMF is removed by vacuum drying to obtain a polymer film (PEO / PVDF-HFP film) with a thickness of approximately 20 μm. Several PEO / PVDF-HFP films are prepared in the same manner.

[0126] (3) Disperse the LLTO sample in deionized water, and use ultrasonic treatment with a power of 100W for 30 minutes to peel it off. Then, centrifuge at 2000rpm for 5 minutes, collect the supernatant, and obtain the LLTO nanowire dispersion.

[0127] (4) The LLTO nanowire dispersion obtained in step (3) was subjected to vacuum filtration. A vacuum filtration device with a core diameter of 10 cm was used, equipped with an aqueous microporous filter membrane with a pore size of 0.45 μm and a diameter of 11 cm. The filtration was carried out at a vacuum of 0.09 MPa for 30 min until no obvious moisture residue was left in the resulting film. Then, it was placed in a vacuum drying oven at 60 °C and dried for 12 h to obtain an inorganic ion conductor membrane. The thickness of the inorganic ion conductor membrane was approximately 20 μm and the area was 60 cm². 2 The mass is approximately 0.25 g. In this membrane, LLTO nanowires oriented inwards account for more than 70% of the total number of nanowires. Several inorganic ion-conducting membranes were prepared using the same method.

[0128] (5) The PEO / PVDF-HFP polymer membrane prepared in step (2) and the LLTO inorganic ion conductor membrane prepared in step (4) are tightly bonded under a pressure of 20 MPa. The two membrane materials are randomly stacked (e.g., inorganic → inorganic → polymer → polymer → inorganic → polymer) to a preset thickness. Then, the block is cut into four equal parts and cold-pressed. The above process is repeated twice, and after three rounds of stacking, a cuboid structure with a thickness of 1 cm is finally formed. It is placed under vacuum drying at 60℃ for 12 h to complete the preparation of the composite block.

[0129] (6) The composite block obtained in step (5) is cut into the solid electrolyte with a thickness of 200 μm at -20° using a slicer at an angle of 30°.

[0130] (7) The solid electrolyte obtained in step (6) is cut into round pieces with a diameter of 10 mm using a cutting machine. Lithium iron phosphate (LFP) is used as the positive electrode material of the full battery. The CR2025 button battery is assembled in a glove box according to the battery assembly process and then subjected to electrochemical performance testing.

[0131] Figure 2 The image shows a surface scanning electron microscope image of the solid electrolyte prepared in Example 1. It can be seen that the electrolyte obtained was composed of... LLTOThe structure is a multilayer structure composed of alternating and regularly arranged inorganic ion conductor membranes and PEO / PVDF-HFP polymer membranes.

[0132] Figure 3 The image shown is a cross-sectional scanning electron microscope image of the solid electrolyte prepared in Example 1. It can be seen that the total thickness of the electrolyte is approximately 200 μm. Importantly, the inorganic ion-conducting film exhibits a continuous distribution from top to bottom throughout the entire cross-section.

[0133] Figure 4 The graphs show the ionic conductivity at room temperature of the solid electrolytes prepared in Examples 1, 2, 3, 4, 5, 6, 7, and 8. It can be seen that Example 1 exhibits the highest ionic conductivity, reaching 4.15 mS. cm -1 The ionic conductivity of Examples 2, 3, 4, 5, 6, and 7 was 3.15 mS. cm -1 3.21 mS cm -1 2.90 mS cm -1 1.54 mS cm -1 3.82 mS cm -1 0.09 mS cm -1 All are at 10 -1 ~10 mS cm -1 Order of magnitude, meeting the basic requirements for electrolyte ionic conductivity (≥10) of all-solid-state lithium batteries. -1 mS cm -1 ).

[0134] Figure 5 The critical current density plot of the solid electrolyte prepared in Example 1 shows that the critical current density of the electrolyte is as high as 1.4 mA cm⁻¹. -2 This data clearly demonstrates that the solid electrolyte has a strong ability to resist lithium dendrite growth.

[0135] Figure 6The first charge-discharge curves of the solid-state batteries corresponding to the solid-state electrolytes of Examples 1, 2, 3, 4, 5, 6, and 7 are shown. It can be seen that the overpotentials of each example are 29mV, 34mV, 33mV, 108mV, 62mV, 71mV, and 157mV, respectively. The solid-state electrolyte prepared in Example 1 has a lower overpotential, and the corresponding solid-state battery exhibits faster reaction kinetics, indicating that the solid-state electrolyte obtained by the stacking and pressurizing layering method has superior performance.

[0136] Figure 7 The graphs show the full-cell cycling performance of the solid electrolytes prepared in Example 1 and Comparative Examples 1, 2, and 3, indicating that the solid electrolyte prepared in Example 1 has better cycling stability and higher capacity retention.

Claims

1. A solid electrolyte, characterized in that, The device includes a multilayer inorganic ion conductor membrane and a multilayer polymer membrane stacked together, with the inorganic ion conductor membrane and polymer membrane alternating between each other. The inorganic ion conductor membrane is composed of one-dimensional inorganic ion conductors, which are preferentially oriented and have their axial direction parallel to the plane of the inorganic ion conductor membrane. The thickness direction of the solid electrolyte is perpendicular to the stacking direction of the inorganic ion conductor membrane and the polymer membrane.

2. The solid electrolyte according to claim 1, characterized in that, The one-dimensional inorganic ionic conductor is Li3N, Li2S-P2S5, or Li 0.33 La 0.56 TiO3, Li 1.3 Al 0.3 Ti 1.7 (PO4)3, Li7P3S 11 Li 10 GeP2S 12 Lithium and phosphorus co-doped hydroxyapatite, Na3PS4, Na3Zr2Si2PO 12 K3SbS4, K2ZnCl4, CaTiO3, Ca3(PO4)2, Mg3(PO4)2, MgMoO4, ZnMoO4, Zn3(PO4)2, Al2O3, AlPO4, lithium cobalt nickel iron manganese oxides, sodium cobalt nickel iron manganese sulfides, potassium cobalt nickel iron manganese phosphates, calcium magnesium aluminum zinc copper oxyfluorides, magnesium cobalt nickel iron manganese sulfides, zinc cobalt nickel iron manganese phosphates or aluminum cobalt nickel iron manganese oxides.

3. The solid electrolyte according to claim 1, characterized in that, The polymer in the polymer film is one or more of the following: polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polypropylene carbonate-polyethylene oxide, polyvinyl carbonate, polyacrylic acid, polytetrahydrofuran, polybutadiene, and polyethylene glycol.

4. The solid electrolyte according to claim 1, characterized in that, Based on the total mass of the solid electrolyte as 100%, the mass fraction of the inorganic ionic conductor is 40%~45%, and the mass fraction of the polymer membrane is 55%~60%.

5. The solid electrolyte according to claim 1, characterized in that, The inorganic ion conductor film has a thickness of 10~20μm, and the polymer film has a thickness of 20~30μm.

6. The solid electrolyte according to claim 1, characterized in that, The polymer membrane contains dissociated inorganic metal salts and inorganic ionic conductors; the inorganic ionic conductors are the same as those in the inorganic ionic conductor membrane; the dissociated inorganic metal salts and the inorganic ionic conductors have the same metal cations.

7. The solid electrolyte according to claim 6, characterized in that, The dissociated inorganic metal salt is one of lithium salt, sodium salt, potassium salt, calcium salt, magnesium salt, zinc salt, and aluminum salt.

8. The method for preparing the solid electrolyte according to any one of claims 1 to 7, characterized in that, One of the following methods: Method 1: Prepare multiple polymer films and multiple inorganic ion conductor films separately, wherein the one-dimensional inorganic ion conductors in the inorganic ion conductor films are preferentially oriented; assemble the polymer films and inorganic ion conductor films together by stacking and cold pressing or rolling to obtain a solid electrolyte of a predetermined thickness; Method 2: Prepare a polymer membrane, a polymer slurry, and an inorganic ionic conductor dispersion, respectively; coat the polymer membrane with the inorganic ionic conductor dispersion and dry to form an inorganic ionic conductor membrane. During the coating and drying stages, an external field is used to preferentially align the one-dimensional inorganic ionic conductors; then coat the polymer slurry and dry to form a polymer membrane; repeat the coating and drying process of the inorganic ionic conductor dispersion and polymer slurry alternately until a solid electrolyte of a predetermined thickness is obtained. Method 3: Prepare polymer slurry and inorganic ionic conductor dispersion separately; inject the polymer slurry and inorganic ionic conductor dispersion into different inlets of the microfluidic chip. The polymer slurry and inorganic ionic conductor dispersion form a parallel fluid layer in the main channel by utilizing laminar flow characteristics. The one-dimensional inorganic ionic conductor is preferentially oriented and aligned by an external field. Subsequently, the polymer slurry and inorganic ionic conductor dispersion are solidified during the flow process by ultraviolet light, heat or chemical means to obtain a solid electrolyte of a predetermined thickness.

9. A solid-state battery, characterized in that, The solid electrolyte according to any one of claims 1 to 7 includes a positive electrode, a negative electrode, and a solid electrolyte located between the positive and negative electrodes, wherein the axial direction of the one-dimensional inorganic ionic conductor is perpendicular to both the plane containing the positive electrode and the plane containing the negative electrode.

10. The solid-state battery according to claim 9, characterized in that, The solid-state battery is a lithium-ion solid-state battery, a sodium-ion solid-state battery, a potassium-ion solid-state battery, a calcium-ion solid-state battery, a zinc-ion solid-state battery, a magnesium-ion solid-state battery, or an aluminum-ion solid-state battery.

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