A solid-state electrolyte membrane, a lithium ion battery and a preparation method thereof

Abstract

This application discloses a solid electrolyte membrane, a lithium-ion battery, and a method for preparing the same. The method for preparing the solid electrolyte membrane includes: pulverizing a solid electrolyte material or a solid electrolyte precursor material to obtain a powder; mixing the powder, a fiberizable binder, and an additive uniformly to obtain a first mixture; fiberizing the fiberizable binder in the first mixture to obtain a second mixture; calendering the second mixture into a solid electrolyte membrane preform with a thickness of 10 μm to 1000 μm; and calcining the solid electrolyte membrane preform to obtain a solid electrolyte membrane. The solid electrolyte membrane, lithium-ion battery, and method for preparing the same provided by this application are simple to prepare, do not use any slurry solvents in the entire preparation process, are environmentally friendly, and the materials and equipment used in the preparation process are readily available, resulting in low production costs and facilitating large-scale production.

Description

Technical Field

[0001] This application relates to the field of battery technology, and more specifically, to a solid electrolyte membrane, a lithium-ion battery, and a method for preparing the same. Background Technology

[0002] Lithium-ion batteries are widely used in mobile devices and new energy vehicles due to their high energy density, high capacity, long battery life, and high safety performance. Traditional lithium-ion batteries use liquid electrolytes, but liquid electrolytes have a low flash point, which can lead to spontaneous combustion or even explosions under abnormal conditions such as high-current discharge, overcharging, or internal short circuits. Solid-state lithium-ion batteries use non-flammable or non-flammable solid electrolytes instead of the flammable organic electrolytes in traditional lithium-ion batteries, fundamentally solving the safety problems of lithium-ion batteries. Solid-state lithium-ion batteries and the solid electrolyte membranes used in them have become a focus of research and development in recent years.

[0003] Currently, the most common methods for preparing solid electrolyte membranes are ceramic thin film forming methods, such as casting, roll forming, and screen printing. These methods are inexpensive and suitable for large-scale industrial production, but they have some drawbacks. Casting often uses organic solvents, which is not only costly but also causes serious environmental pollution. Furthermore, its process formulation is complex and unsuitable for preparing thicker solid electrolyte membranes, and it is prone to cracking during drying. Existing roll forming methods typically require first uniformly dispersing ceramic powder in a solvent, adding plasticizers, binders, and other additives to create a high-solids content blank, which is then kneaded on a rolling mill to ensure thorough mixing of the powder and plasticizer. Repeated kneading ensures high uniformity of the mixture and removes air bubbles. Screen printing has very high requirements for parameters such as powder particle size, grain shape, surface properties, and packing density. In addition, methods such as chemical vapor deposition, spray pyrolysis, sputtering, and plasma spraying for preparing solid electrolyte membranes usually require substrate materials and have high production costs, making them unsuitable for large-scale production. Another method for preparing solid electrolyte membranes is to first prepare synthetic precursor powders using solid-state sintering, and then press and sinter the solid electrolyte membrane using tablet molding. Zhang P et al. prepared Lil using the sol-gel method. .4 Al 0.4 Ti 1.4 Ge 0.2 (PO4)3 material powder was further processed to prepare a solid electrolyte ceramic membrane via sintering. Xu et al. prepared Li... 1.4 Al 0.4 Ti 1.6(PO4)3 solid electrolyte ceramic membranes exhibit significantly reduced sintering temperatures under 45 MPa pressure and rapid heating conditions. However, the aforementioned molding method introduces internal stress, leading to easy fragmentation upon demolding after molding. Furthermore, the mold can cause localized density differences in the material, and the dimensions of solid electrolyte membranes prepared using the molding method are limited by the mold, resulting in inaccurate thickness control and low density.

[0004] Therefore, there is an urgent need for an environmentally friendly and simple method for preparing solid electrolyte membranes. Summary of the Invention

[0005] This application provides a solid electrolyte membrane, a lithium-ion battery, and a method for preparing the same. The method for preparing the solid electrolyte membrane is environmentally friendly and has a simple process.

[0006] To solve one or more of the above-mentioned technical problems, the technical solution adopted in this application is:

[0007] In a first aspect, this application provides a method for preparing a solid electrolyte membrane, the method comprising:

[0008] Solid electrolyte materials or solid electrolyte precursor materials are pulverized to obtain powder;

[0009] The powder, the fiberizable binder, and the additives are mixed evenly to obtain a first mixture;

[0010] The fiberizable binder in the first mixture is fiberized to obtain a second mixture;

[0011] The second mixture is calendered into a solid electrolyte membrane preform with a thickness of 10 μm-1000 μm;

[0012] The solid electrolyte membrane blank is calcined to obtain a solid electrolyte membrane.

[0013] Furthermore, the mass fraction of the fiberizable binder in the first mixture is 5-50%.

[0014] Furthermore, the solid electrolyte material includes at least one of lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium tantalum oxide, lithium lanthanum titanium oxide, and lithium phosphorus oxygen nitrogen.

[0015] Furthermore, the solid electrolyte precursor material includes a mixture of solid electrolyte precursors prepared by the sol-gel method.

[0016] Furthermore, the fiberizable adhesive includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, and sodium alginate.

[0017] Furthermore, the additives include at least one of polyvinyl carbonate, polypropylene carbonate, polytrimethylene carbonate, polyethylene oxide, polyvinylpyrrolidone, stearic acid, etc.

[0018] Furthermore, the first mixture is fed into a shear-effect mixer for processing, and the fiberizable binder is fiberized to obtain a second mixture.

[0019] Furthermore, the mixer includes at least one of a high-speed planetary ball mill, a high-speed shear mill, an air jet mill, and a screw extruder.

[0020] Furthermore, the rolling temperature is 25-200℃, and the rolling pressure is 10-100t.

[0021] Preferably, the rolling temperature is 100-150°C.

[0022] Furthermore, the calcination temperature is 600-1000℃.

[0023] Secondly, this application also provides a solid electrolyte membrane, wherein the solid electrolyte membrane is a solid electrolyte membrane prepared by the above preparation method.

[0024] Thirdly, this application also provides a lithium-ion battery, the lithium-ion battery comprising a positive electrode, a negative electrode and a solid electrolyte membrane located between the positive electrode and the negative electrode, wherein the solid electrolyte membrane is the aforementioned solid electrolyte membrane.

[0025] According to the specific embodiments provided in this application, the following technical effects are disclosed:

[0026] This application provides a solid electrolyte membrane, a lithium-ion battery, and a method for preparing the same. The preparation method is simple and includes sequential material crushing, dry powder mixing, fiber crushing, roll forming, and sintering to form a film. No slurry solvent is used in the entire preparation process, which is environmentally friendly. The materials and equipment used in the preparation process are readily available, the production cost is low, and it is conducive to large-scale production.

[0027] Of course, any product implementing this application does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 A flowchart illustrating the preparation method of the solid electrolyte membrane provided in this application embodiment;

[0030] Figure 2 This is a SEM image of the cross-section of the solid electrolyte membrane preform prepared in Example 1 of this application;

[0031] Figure 3 This is a SEM image of the cross-section of the solid electrolyte membrane provided in Embodiment 1 of this application;

[0032] Figure 4 This is an enlarged SEM image of the cross-section of the solid electrolyte membrane provided in Embodiment 1 of this application. Detailed Implementation

[0033] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art are within the scope of protection of this application.

[0034] This application provides a solid electrolyte membrane, a lithium-ion battery, and a method for preparing the same. The preparation method is simple, does not use organic solvents, is environmentally friendly, and the materials and equipment used in the preparation process are readily available, resulting in low production costs and facilitating large-scale production.

[0035] Figure 1 This is a flowchart illustrating the preparation method of the solid electrolyte membrane provided in the embodiments of this application, as shown below. Figure 1 As shown, a method for preparing a solid electrolyte membrane includes:

[0036] S1: Powder is obtained by pulverizing solid electrolyte materials or solid electrolyte precursor materials.

[0037] In this application, there is no particular limitation on the solid electrolyte material. Any known solid electrolyte material can be used in this application, including but not limited to one or more of oxide solid electrolytes, sulfide solid electrolytes, halide solid electrolytes, hydride solid electrolytes, boride solid electrolytes, and nitride solid electrolytes.

[0038] The oxide solid electrolyte may comprise one or more garnet ceramics, LISICON-type oxides, NASICON-type oxides, and perovskite-type ceramics. For example, one or more garnet ceramics may be selected from the group consisting of: Li 6.5 La3Zr 1.75 Te 0.25 O 12 Li7La3Zr2O 12 Li 6.2Ga 0.3 La 2.95 Rb 0.05 Zr2O 12 Li 6.85 La 2.9 Ca 0.1 Zr 1.75 Nb 0.25 O 12 Li 6.25 Al 0.25 La3Zr2O 12 Li 6.75 La3Zr 1.75 Nb 0.25 O 12 Li 6.75 La3Zr 1.75 Nb 0.25 O 12 And combinations thereof. One or more LISICON-type oxides may be selected from the group consisting of: Li 14 Zn(GeO4)4, Li 3+x (P 1-x Si x O4 (where 0 < x < 1), Li 3+x Ge x V 1-x O4 (where 0 < x < 1) and combinations thereof. One or more NASICON-type oxides may be defined by LiMM′(PO4)3, where M and M′ are independently selected from Al, Ge, Ti, Sn, Hf, Zr, and La. For example, in some variants, one or more NASICON-type oxides may be selected from the group consisting of: Li 1+x Al x Ge 2-x (PO4)3(LAGP) (where 0 ≤ x ≤ 2), Li 1+x Al x Ti 2-x (PO4)3(LATP) (where 0 ≤ x ≤ 2), Li 1+x Y x Zr 2-x (PO4)3(LYZP) (where 0≤x≤2), Li 1.3 Al 0.3 Ti 1.7 (PO4)3, LiTi2(PO4)3, LiGeTi(PO4)3, LiGe2(PO4)3, LiHf2(PO4)3, and combinations thereof. One or more perovskite ceramics may be selected from the group consisting of: Li 3.3 La 0.53 TiO3, LiSr 1.65 Zr1.3 Ta 1.7 O9、Li 2x-y Sr 1-x Ta y Zr 1-y O3 (where x = 0.75y and 0.60 < y < 0.75), Li 3 / 8 Sr 7 / 16 Nb 3 / 4 Zr 1 / 4 O3, Li 3x La (2 / 3-x) TiO3 (where 0 < x < 0.25) and combinations thereof.

[0039] The sulfide solid electrolyte may include one or more sulfide-based materials selected from the group consisting of: Li2S-P2S5, Li2S-P2S5-MS x (where M is Si, Ge, and Sn and 0 ≤ x ≤ 2), Li 3.4 Si 0.4 P 0.6 S4, Li 10 GeP2S 11.7 O 0.3 Li 9.6 P3S 12 Li7P3S 11 Li9P3S9O3, Li 10.35 Si 1.35 P 1.65 S 12 Li 9.81 Sn 0.81 P 2.19 S 12 Li 10 (Si 0.5 Ge 0.5 P2S 12 Li (Ge 0.5 Sn 0.5 P2S 12 Li(Si) 0.5 Sn 0.5 PS 12 Li 10 GeP2S 12 (LGPS), Li6PS5X (where X is Cl, Br, or I), Li7P2S8I, Li 10.35 Ge 1.35 P 1.65 S 12 Li 3.25 Ge 0.25 P 0.75 S4, Li 10 SnP2S12 Li 10 SiP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 C 10.3 , (1-x) P2S 5-x Li₂S (where 0.5 ≤ x ≤ 0.7) and their combinations.

[0040] The halide solid electrolyte may include one or more halide-based materials selected from the group consisting of: Li₂CdC 14 Li2MgC 14 Li2Cd I4 , Li2ZnI4, Li3OCl, LiI, Li5ZnI4, Li3OCl 1-x Br x (where 0 < x < 1) and their combinations.

[0041] The boride solid electrolyte may include one or more borate-based materials selected from the group consisting of Li2B4O7, Li2O-(B2O3)-(P2O5), and combinations thereof.

[0042] The nitride solid electrolyte may include one or more nitride-based materials selected from the group consisting of Li3N, Li7PN4, LiSi2N3, LiPON, and combinations thereof.

[0043] The hydride solid electrolyte includes one or more hydride-based materials selected from the group consisting of: Li3AlH6, LiBH4, LiBH4-LiX (where X is one of Cl, Br and I), LiNH2, Li2NH, LiBH4-LiNH2, and combinations thereof.

[0044] Furthermore, the solid electrolyte precursor material includes a mixture of solid electrolyte precursors prepared by the sol-gel method.

[0045] It is known to select appropriate solid electrolyte precursors based on the type of solid electrolyte material to be prepared; as an illustrative embodiment, the process of preparing the solid electrolyte precursor mixture using the sol-gel method includes:

[0046] 1): Dissolve LiNO3, Al(NO3)3·9H2O and NH4H2PO4 in a solvent to obtain a third mixture.

[0047] 2): Mix isopropyl titanate and acetylacetone to obtain a fourth mixture.

[0048] In this embodiment, the mass ratio of isopropyl titanate to acetylacetone is 1:1.

[0049] 3): The fourth mixture is added to the third mixture and mixed evenly to obtain a solid electrolyte precursor sol.

[0050] 4): After aging the solid electrolyte precursor sol for a preset time, LATP solid electrolyte precursor gel is obtained.

[0051] In this embodiment, the preset time is 5-7 hours. Further, the preset time can be 5, 5.5, 6, 6.5, or 7 hours, or a specific value between these values, preferably 6 hours. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0052] 5): The solid electrolyte precursor gel is dried to obtain a solid electrolyte precursor mixture.

[0053] S2: Mix the powder, the fiberizable binder and the additives evenly to obtain a first mixture.

[0054] By mixing the gel with a fiberizable binder, solid electrolyte particles are formed during the sintering process.

[0055] In this embodiment of the application, the fiberizable adhesive includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, styrene-butadiene rubber, nitrile rubber, sodium carboxymethyl cellulose, polyacrylic acid, polyacrylonitrile, and sodium alginate.

[0056] Furthermore, the additives include at least one of polyvinyl carbonate, polypropylene carbonate, polytrimethylene carbonate, polyethylene oxide, polyvinylpyrrolidone, stearic acid, etc.

[0057] Furthermore, the mass fraction of the fiberizable adhesive in the first mixture is 5-50%. More specifically, the mass fraction of the fiberizable adhesive in the first mixture can be 5%, 10%, 20%, 30%, 40%, or 50%, and specific values ​​between the above values, preferably 5-20%. Due to space limitations and for the sake of brevity, the present invention will not exhaustively list the specific values ​​included in the range.

[0058] S3: Fiberize the fiberizable binder in the first mixture to obtain a second mixture.

[0059] The fiberization of adhesives refers to the formation of fibers by the regular arrangement of adhesive materials in a certain direction under the action of shear force.

[0060] More specifically, the first mixture is fed into a shear-effect mixer for processing, and the fiberizable binder is fiberized to obtain a second mixture. In this embodiment, the mixer includes at least one of a high-speed planetary ball mill, a high-speed shear mill, an air jet mill, and a screw extruder. In specific implementation, it can be set according to the actual needs of the user, and no specific limitation is made here.

[0061] S4: The second mixture is calendered into a solid electrolyte membrane preform with a thickness of 10μm-1000μm.

[0062] During calendering, the fibrous binder becomes further fibrous, and a higher degree of fibrosis in the binder facilitates the formation of a more complete three-dimensional network structure. Additionally, the processing aids soften during calendering, bonding tightly with the solid electrolyte powder, thus aiding in the formation of the solid electrolyte membrane preform.

[0063] To effectively control the thickness and compaction density of the solid electrolyte membrane, in this embodiment, the second mixture is sequentially subjected to vertical and horizontal rolling to obtain a solid electrolyte membrane preform. First, the second mixture is vertically rolled, passing from top to bottom through the gap between two hot-pressing rollers, and formed under the extrusion of the two rollers to obtain a pre-formed solid electrolyte membrane preform. It is understood that adjusting the gap between the hot-pressing rollers based on the thickness requirements of the solid electrolyte membrane is feasible; this application does not specifically limit the gap between the hot-pressing rollers, as long as it meets the relevant process requirements. Next, the pre-formed solid electrolyte membrane preform is horizontally rolled, passing horizontally through the gap between two horizontal rollers, and undergoing fiberization under the extrusion of the two horizontal rollers to obtain a solid electrolyte membrane preform with higher strength. During the horizontal rolling process, the gap between the two horizontal rollers can be gradually reduced until the thickness of the solid electrolyte membrane preform reaches the preset thickness. The preset thickness of the solid electrolyte membrane preform is 1μm-1000μm. More specifically, the thickness of the solid electrolyte membrane is 1μm, 100, 200, 400, 600, 800 and 1000μm, preferably 1-100μm. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0064] In this embodiment of the application, the rolling temperature is 25-200℃, preferably 100-150℃. More specifically, the rolling temperature can be 25, 50, 100, 110, 120, 130, 150, 170 or 200℃. Users can choose according to their actual needs, and no specific limitation is made here.

[0065] Furthermore, the rolling pressure is 10-100t. More specifically, the rolling pressure can be 10, 30, 50, 70, 90 or 100t, and the user can choose according to actual needs. No specific limitation is made here.

[0066] S5: The solid electrolyte membrane blank is calcined to obtain a solid electrolyte membrane.

[0067] In this embodiment, the calcination temperature is 600-1000℃. More specifically, the calcination temperature can be 600, 700, 800, 900, or 1000℃, and the user can choose according to actual needs; no specific limitation is made here. Furthermore, the specific heating program can be set according to the composition of the second mixture. The principle of setting the heating program is to ensure that the binder and additives are fully decomposed in the low-temperature region and the solid electrolyte is fully crystallized in the high-temperature region.

[0068] This application also provides a solid electrolyte membrane, which is the solid electrolyte membrane prepared by the above-described preparation method. Since the solid electrolyte membrane prepared in this application is obtained without the use of solvents, it does not contain solvent residues or impurities, making it more advantageous for industrial applications.

[0069] This application also provides a lithium-ion battery, the lithium-ion battery including a positive electrode, a negative electrode and a solid electrolyte membrane located between the positive electrode and the negative electrode, the solid electrolyte membrane being the solid electrolyte membrane described above.

[0070] The negative electrode includes a current collector and a layer of negative electrode active material covering the surface of the current collector. The negative electrode current collector is not particularly limited, as long as it is conductive and does not cause chemical changes in the battery. Specifically, the negative electrode current collector includes, but is not limited to, elemental aluminum, copper, nickel, or zinc. For example, the negative electrode current collector can be elemental copper, such as copper foil. Furthermore, the shape of the negative electrode current collector can be any of the following: foil shape, plate shape, or grid shape.

[0071] The negative electrode active material layer includes a negative electrode binder, a negative electrode active material, and a negative electrode conductive agent. The negative electrode binder includes, but is not limited to, polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, etc. The negative electrode active material includes at least one of graphite, soft carbon, hard carbon, silicon oxide, or silicon carbon. The negative electrode conductive agent may include carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, SuperP, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, poly(3,4-ethylenedioxythiophene)polysulfonated styrene, etc. The negative electrode active material may include lithium-based negative electrode active materials, comprising, for example, lithium metal and / or lithium alloys; by way of illustrative example and not a limitation thereof, the negative electrode active material may be a silicon-based negative electrode active material, comprising silicon, such as silicon alloys, silicon oxide, or combinations thereof, and in some embodiments may be mixed with graphite; in other embodiments, the negative electrode active material may include carbon-based negative electrode active materials, comprising one or more of graphite, graphene, carbon nanotubes (CNTs), and combinations thereof; in still further embodiments, the negative electrode active material includes one or more lithium-accepting negative electrode active materials, such as lithium titanium oxide (Li4Ti5O). 12 One or more transition metals (e.g., tin (Sn)), one or more metal oxides (e.g., vanadium oxide (V₂O₅), tin oxide (SnO), titanium dioxide (TiO₂)), titanium niobium oxide (Ti) x Nb y O z , where 0≤x≤2, 0≤y≤24 and 0≤z≤64, metal alloys (such as copper-tin alloy (Cu6Sn5)) and one or more metal sulfides (such as iron sulfide (FeS)).

[0072] The above materials are merely illustrative examples of the selected negative electrode materials. It is understood that any known negative electrode material, including binders, negative electrode active materials, negative electrode conductive agents, and other additives, can be used in this application without departing from the inventive concept of this application.

[0073] In this embodiment, the positive electrode includes a positive current collector and a positive active material layer covering the surface of the positive current collector. The positive active material layer includes a positive active material, which may be formed from multiple positive active particles containing one or more transition metal cations, such as manganese (Mn), nickel (Ni), cobalt (Co), chromium (Cr), iron (Fe), vanadium (V), and combinations thereof. In some embodiments, the positive active material layer further includes an electrolyte, such as multiple electrolyte particles.

[0074] The positive electrode active material can also be one of layered oxides, spinels, and polyanions. For example, layered oxides (e.g., rock salt layered oxides) contain one or more lithium-based positive electrode active materials selected from: LiCoO2, LiNi x Mn y Co 1-x-y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi 1-x-y Co x Al y O2 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), LiNi x Mn 1-x O2 (where 0 ≤ x ≤ 1) and Li 1+x MO2 (where M is one of Mn, Ni, Co and Al and 0≤x≤1).

[0075] In one embodiment, one or more lithium-based positive electrode active materials may optionally be coated and / or doped. Furthermore, in some embodiments, one or more lithium-based positive electrode active materials may optionally be mixed with one or more conductive materials that provide an electronic conduction path and / or at least one polymeric binder material that improves the structural integrity of the positive electrode. For example, the positive electrode active material layer may comprise more than or equal to about 30 wt% to less than or equal to about 98 wt% of one or more lithium-based positive electrode active materials; more than or equal to about 0 wt% to less than or equal to about 30 wt% of conductive material; and more than or equal to about 0 wt% to less than or equal to about 20 wt% of binder, and in some aspects, optionally more than or equal to about 1 wt% to less than or equal to about 20 wt% of binder.

[0076] In a preferred embodiment of this application, the positive electrode active material layer may optionally be mixed with a binder such as polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), nitrile rubber (NBR), styrene-ethylene-butene-styrene copolymer (SEBS), styrene-butadiene-styrene copolymer (SBS), lithium polyacrylate (LiPAA), sodium polyacrylate (NaPAA), sodium alginate, lithium alginate, and combinations thereof. The conductive material may include carbon-based materials, powdered nickel or other metal particles, or conductive polymers. Carbon-based materials may include particles such as carbon black, graphite, acetylene black (e.g., KETCHENTM black or DENKATM black), carbon fibers and nanotubes, graphene, etc. Examples of conductive polymers include polyaniline, polythiophene, polyacetylene, polypyrrole, etc.

[0077] The embodiments of the present invention will be described in more detail below through examples. However, the embodiments of the present invention are not limited to these examples.

[0078] Example 1

[0079] A method for preparing a solid electrolyte membrane, the method comprising the following steps:

[0080] Lithium lanthanum titanium oxide (LLTO) was pulverized to obtain lithium lanthanum titanium oxide (LLTO) powder with a D50 of 3 micrometers.

[0081] Lithium lanthanum titanium oxide (LLTO) powder with a D50 of 3 micrometers and polytetrafluoroethylene (PTFE) with a particle size of 500 micrometers were mixed at a mass ratio of 6:4. The mixture was stirred at 1000 rpm for 1 hour in a mixer to ensure that the lithium lanthanum titanium oxide (LLTO) powder and polytetrafluoroethylene (PTFE) were mixed evenly.

[0082] The uniformly mixed lithium lanthanum titanium oxide (LLTO) powder and polytetrafluoroethylene (PTFE) are first fed into a high-speed shear mill and mixed at a frequency of 50 Hz for 1 hour to achieve preliminary fiberization of the material. Next, an air jet mill is used to further process the preliminary fiberized material to achieve a loose state. The feed pressure is 0.5-1.3 MPa, the feeding pressure is 0.5-1.3 MPa, and the number of processing cycles is 1-5.

[0083] The mixture obtained above is subjected to vertical and horizontal rolling processes sequentially to obtain a solid electrolyte composite membrane preform. Specifically, the mixture is first passed from top to bottom through the gap between two hot press rollers, and under the extrusion of the two hot press rollers, a preliminary solid electrolyte membrane preform is formed. The vertical rolling pressure is 5t, the vertical rolling temperature is 150℃, and the gap width between the two hot press rollers is 0.8 micrometers. Next, the preliminary solid electrolyte membrane preform is passed horizontally through the gap between two horizontal rollers, and under the extrusion of the two horizontal rollers, it is further fiberized to obtain a solid electrolyte membrane preform with higher strength. The gap between the two horizontal rollers is gradually reduced until the thickness of the solid electrolyte membrane preform is 60 micrometers, and the horizontal rolling pressure is 5t. Figure 2 This is a SEM image of the cross-section of the solid electrolyte membrane preform prepared according to an embodiment of this application.

[0084] The solid electrolyte membrane was obtained by calcining the above solid electrolyte membrane preform at 900°C for 3 hours. Figure 3 This is a SEM image of the cross-section of the solid electrolyte membrane provided in an embodiment of this application. Figure 4 This is a magnified SEM image of the cross-section of the solid electrolyte membrane provided in the embodiments of this application, as shown below. Figure 3 As shown, and also refer to Figure 4 It can be observed that the prepared solid electrolyte membrane has a dense structure.

[0085] Example 2

[0086] A method for preparing a solid electrolyte membrane, the method comprising the following steps:

[0087] LiNO3, Al(NO3)3·9H2O, and NH4H2PO4 were weighed according to the stoichiometric ratio of LATP and dissolved in a solvent, stirred to form a homogeneous solution. Two drops of water or nitric acid were added to aid dissolution. Isopropyl titanate and acetylacetone were mixed evenly according to the same stoichiometric ratio and then added to the aforementioned solution and mixed thoroughly. At room temperature, a lithium aluminum titanium phosphate (LATP) sol was obtained. After aging the LATP sol for 6 hours, a lithium aluminum titanium phosphate (LATP) gel was obtained. The LATP gel was dried to obtain a lithium aluminum titanium phosphate solid electrolyte precursor material. The lithium aluminum titanium phosphate solid electrolyte precursor material was pulverized to obtain a lithium aluminum titanium phosphate (LATP) dry gel powder.

[0088] The lithium aluminum titanium phosphate (LATP) dry gel powder, polytetrafluoroethylene (PTFE) with a particle size of 500 micrometers and styrene-butadiene rubber (SBR) were mixed in a mass ratio of 8:1:1 and stirred at 600 rpm for 1 hour in a mixer to ensure uniform mixing.

[0089] The uniformly mixed lithium aluminum titanium phosphate (LATP) dry gel powder, polytetrafluoroethylene (PTFE) and styrene-butadiene rubber (SBR) were added to a screw extruder and mixed at 25°C for 1 hour to obtain fibrous material. The screw extruder had a rotation speed of 600 rpm, a flow rate of 10 kg / h, and a power of 2.5 kW.

[0090] The mixture obtained above is subjected to vertical and horizontal rolling processes sequentially to obtain a solid electrolyte composite membrane preform. Specifically, the mixture is first passed from top to bottom through the gap between two hot press rollers, and under the extrusion of the two hot press rollers, a preliminary solid electrolyte membrane preform is formed. The vertical rolling pressure is 5t, and the vertical rolling temperature is 130℃. Next, the preliminary solid electrolyte membrane preform is passed horizontally through the gap between two horizontal rollers, and under the extrusion of the two horizontal rollers, it is further fiberized to obtain a solid electrolyte membrane preform with higher strength. The gap between the two horizontal rollers is gradually reduced until the thickness of the solid electrolyte membrane preform is 50 micrometers, and the horizontal rolling pressure is 5t.

[0091] The solid electrolyte membrane blank was calcined at 800°C for 6 hours to obtain a solid electrolyte membrane, wherein the solid electrolyte membrane is a dense sheet-like lithium aluminum titanium phosphate (LATP) ceramic.

[0092] As can be seen from the above, the embodiments of this application provide a solid electrolyte membrane, a lithium-ion battery and a method for preparing the same. The preparation method includes material crushing, dry powder mixing, fiber crushing, roll forming and sintering to form a film in sequence. In the entire preparation process, no slurry solvent is added and there is no toxic gas emission. The materials and equipment used in the preparation process are easy to obtain, the production cost is low, and it is conducive to large-scale production. The prepared solid electrolyte membrane has controllable thickness, high ionic conductivity and high density.

[0093] The foregoing has provided a detailed description of a solid electrolyte membrane, a lithium-ion battery, and a method for preparing the same, as provided in this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of these embodiments are merely for the purpose of helping to understand the method and its core ideas. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for preparing a solid electrolyte membrane, characterized in that, The method for preparing the solid electrolyte membrane includes: Solid electrolyte materials or solid electrolyte precursor materials are pulverized to obtain powder; The powder, the fiberizable binder, and the additives are mixed evenly to obtain a first mixture; the additives include at least one selected from polyvinyl carbonate, polypropylene carbonate, polytrimethylene carbonate, polyethylene oxide, polyvinylpyrrolidone, and stearic acid. The fiberizable binder in the first mixture is fiberized to obtain a second mixture; The second mixture is calendered into a solid electrolyte membrane preform with a thickness of 10 μm-1000 μm; The solid electrolyte membrane preform is calcined at 600℃-1000℃ to obtain a solid electrolyte membrane. The fiberizable binder and additives are fully decomposed in the low-temperature region of the calcination, and the solid electrolyte material is fully crystallized in the high-temperature region of the calcination.

2. The method for preparing a solid electrolyte membrane according to claim 1, characterized in that, The mass fraction of the fiberizable binder in the first mixture is 5-50%.

3. The method for preparing a solid electrolyte membrane according to claim 1, characterized in that, The solid electrolyte material includes at least one of lithium titanium aluminum phosphate, lithium germanium aluminum phosphate, lithium lanthanum zirconium oxide, lithium lanthanum zirconium tantalum oxide, lithium lanthanum titanium oxide, and lithium phosphorus oxygen nitrogen.

4. The method for preparing a solid electrolyte membrane according to claim 1, characterized in that, The fiberizable adhesive includes at least one of polytetrafluoroethylene, polyvinylidene fluoride, polypropylene, polyethylene, styrene-butadiene rubber, nitrile rubber, sodium hydroxymethyl cellulose, polyacrylic acid, polyacrylonitrile, and sodium alginate.

5. The method for preparing a solid electrolyte membrane according to claim 1, characterized in that, The solid electrolyte precursor material includes a mixture of solid electrolyte precursors prepared by the sol-gel method.

6. A solid electrolyte membrane, characterized in that, The solid electrolyte membrane is prepared by the method described in any one of claims 1 to 5.

7. A lithium-ion battery, characterized in that, The lithium-ion battery includes a positive electrode, a negative electrode, and a solid electrolyte membrane located between the positive electrode and the negative electrode, wherein the solid electrolyte membrane is a solid electrolyte membrane prepared by the method according to any one of claims 1 to 5.

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