Solid-state battery and preparation method thereof

Abstract

The invention provides a solid-state battery and a preparation method thereof, the solid-state battery comprises at least one unit cell, and the unit cell comprises a positive plate, a sulfide electrolyte layer, an electrolyte membrane and a negative plate which are stacked in sequence; the negative plate comprises a negative current collector and a negative active layer arranged on the surface of the negative current collector; the negative active layer comprises a negative active material, sulfide electrolyte and a conductive agent; the electrolyte membrane comprises a first polymer and a lithium salt, and the thickness of the electrolyte membrane is 1-10 [mu] m. According to the solid-state battery provided by the invention, ion transmission resistance caused by insufficient interface contact can be relieved to a certain extent, and meanwhile, the mechanical supporting property of the sulfide electrolyte layer is enhanced. In addition, the existence of the electrolyte membrane is also helpful for adjusting the ion current distribution at the interface, and plays a positive role in improving the uniformity of lithium ion deposition and promoting the cycling stability of the battery.

Description

Technical Field

[0001] This application belongs to the field of batteries, and in particular relates to a solid-state battery and its preparation method. Background Technology

[0002] Among existing battery technologies, liquid lithium-ion batteries are widely used in numerous fields due to their relatively mature manufacturing process and stable cycle performance. Their liquid electrolyte system can provide high ionic conductivity at room temperature, which is beneficial for achieving high power output. However, liquid electrolytes suffer from insufficient thermal stability and long-term interfacial side reactions, which limit the safety and energy density of the batteries. This has driven the industry to explore new battery systems with higher performance.

[0003] Solid-state batteries utilize solid electrolytes, which, due to their high thermal stability, effectively enhance the safety of battery systems and are a key focus of next-generation battery development. Among various solid electrolytes, sulfide solid electrolytes exhibit room-temperature ionic conductivity close to that of liquid solid-state batteries, offering potential advantages for high power output and wide-temperature applications.

[0004] In the construction of solid-state batteries, achieving and maintaining tight physical contact between the positive electrode layer, the solid electrolyte layer, and the negative electrode layer is crucial, as it directly affects the actual performance of the solid-state battery. Compared to the fluidity and wettability of liquid electrolytes, the solid-solid interface between solid components is a rigid contact, which is prone to gaps due to insufficient contact or volume changes of electrode materials during cycling. This interface state significantly affects the continuity of ion transport, potentially leading to an increase in interface impedance, and consequently impacting the power characteristics and energy efficiency of the solid-state battery. Simultaneously, uneven interface contact can also cause uneven local current distribution, posing challenges to the long-term cycle stability and safety of solid-state batteries. Summary of the Invention

[0005] In view of this, this application aims to provide a solid-state battery and a method for preparing the same, so as to improve the interfacial contact of the solid-state battery.

[0006] To solve the above-mentioned technical problems, this application is implemented as follows: According to a first aspect of this application, a solid-state battery is provided, the solid-state battery including at least one cell, the cell including a positive electrode, a sulfide electrolyte layer, an electrolyte membrane, and a negative electrode stacked sequentially; the negative electrode including a negative current collector and a negative active layer disposed on the surface of the negative current collector, the negative active layer including a negative active material, a sulfide electrolyte, and a conductive agent; the electrolyte membrane including a first polymer and a lithium salt, the thickness of the electrolyte membrane being 1μm to 10μm.

[0007] This application introduces a polymer electrolyte film with a thickness of 1 μm to 10 μm on the negative electrode side of the sulfide solid electrolyte film, which helps improve the physical contact state of the solid-solid interface in solid-state batteries. This structure can alleviate the ion transport resistance caused by insufficient interface contact to a certain extent, while enhancing the mechanical toughness and supporting strength of the sulfide electrolyte layer. In addition, the presence of this polymer electrolyte film also helps reduce the reduction and decomposition of sulfides on the negative electrode side, regulates the ion flow distribution at the interface, buffers the impact of negative electrode expansion on the solid-solid interface contact, and plays a positive role in improving the uniformity of lithium-ion deposition and promoting battery cycle stability.

[0008] Preferably, the ratio of the thickness of the sulfide electrolyte layer to the thickness of the electrolyte membrane is 3.5~35:1; and / or, the conductivity of the electrolyte membrane at 15℃~25℃ is greater than 5*10⁻⁶. -5 S / cm.

[0009] Preferably, the first polymer includes polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride, and polyvinylidene fluoride. At least one of hexafluoropropylene or polyazide; and / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium tetrafluoroborate, lithium hexafluorophosphate, or lithium perchlorate; and / or, the mass ratio of the first polymer to the lithium salt is (3-5):1.

[0010] Preferably, the negative electrode active layer further includes an elastic composite ion conductor material, which includes an inorganic electrolyte, a second polymer, and a lithium salt.

[0011] Preferably, the inorganic electrolyte has a mass percentage of 1% to 10%; and / or, the average particle size D50 of the inorganic electrolyte is 10 nm to 200 nm.

[0012] Preferably, the second polymer includes polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride, and polyvinylidene fluoride. At least one of hexafluoropropylene, polyazine and its derivatives; and / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium tetrafluoroborate, lithium hexafluorophosphate or lithium perchlorate; and / or, the mass ratio of the first polymer to the lithium salt is (3-4):1.

[0013] Preferably, the positive electrode sheet includes a positive electrode active layer, and the positive electrode active layer includes a positive electrode active material; and / or, the positive electrode active material includes LiNi. x Co y M zO2, wherein M includes at least one of Mn, Al, Zr, Ti, V, Mg, Fe or Mo, 0≤x<1, 0≤y<1, 0≤z<1, and x+y+z=1; and / or, the positive electrode active material further includes a coating layer disposed on its surface, the coating layer including at least one of Li2TiO3, LiNbO3, Li3BO3, Li2ZrO3, LiCoO3, LiPO3, Li2MnO4, Al(PO3)3, La(PO3)3, NaPO3.

[0014] Preferably, on the projection plane along the thickness direction, the projected area of ​​the positive electrode is smaller than the projected area of ​​the negative electrode; and / or, the minimum distance between any point on the projection outline boundary line of the positive electrode and the projection outline boundary line of the negative electrode is D, where 0.1 mm ≤ D ≤ 2.6 mm.

[0015] According to a second aspect of this application, this application provides a method for preparing a solid-state battery as described above. The method includes the following steps: S1. Premixing a positive electrode sheet, a negative electrode sheet, an electrolyte membrane, and a sulfide electrolyte layer; wherein the premixing material for the positive electrode sheet is obtained by mixing a positive active material, a sulfide electrolyte, a conductive agent, a binder, and a solvent; the premixing material for the negative electrode sheet is obtained by mixing a negative active material, a sulfide electrolyte, a conductive agent, and a solvent; the premixing material for the electrolyte membrane is obtained by mixing a first polymer, a lithium salt, and a solvent; the premixing material for the sulfide electrolyte layer is obtained by mixing a sulfide electrolyte, a binder, and a solvent; S2. Coating the premixing material of the positive electrode sheet onto the surface of a positive current collector to prepare a positive electrode sheet; S3. Coating the premixing material of the sulfide electrolyte layer onto the surface of a base layer, and after drying... S4. A sulfide electrolyte layer is formed on the surface of the base layer; S5. The premix of the electrolyte membrane is coated on the surface of the sulfide electrolyte layer and then dried to form an electrolyte membrane on the surface of the sulfide electrolyte layer, thus obtaining a composite electrolyte membrane; S6. When the negative electrode active layer does not include an elastic composite ion conductor material, the premix of the negative electrode sheet is used as a negative electrode slurry; when the negative electrode active layer includes an elastic composite ion conductor material, an elastic composite ion conductor slurry is prepared, and then the elastic composite ion conductor slurry is added to the premix of the negative electrode sheet for mixing to obtain a negative electrode slurry; the negative electrode slurry is coated on the surface of the negative electrode current collector to obtain a negative electrode sheet; S7. The negative electrode sheet and the composite electrolyte membrane are composited by hot rolling to bond the electrolyte membrane to the negative electrode sheet; S8. A solid-state battery is obtained through an assembly process.

[0016] Preferably, in S4, the drying process is to dry at 50°C to 80°C in a vacuum environment for 24 to 72 hours; and / or, in S6, the hot rolling process is to apply pressure of 10 MPa to 200 MPa at 80°C to 120°C.

[0017] Implementing the technical solution of this application has at least the following beneficial effects: by using a polymer electrolyte film with a thickness of 1μm to 10μm on one side of the negative electrode, it can not only enhance the mechanical strength and stability of the sulfide electrolyte layer, but also reduce the reduction and decomposition of sulfides, buffer the impact of interface expansion, shape the stretching interface, ensure the close contact and continuity of the solid-solid interface, and also help to homogenize the interface ion flow and improve the uniformity of lithium ion deposition.

[0018] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the interface of the cell structure provided in Example 1; Among them, Figure 1 The meanings of the reference numerals in the attached figures are as follows: 1. Positive electrode sheet; 11. Positive electrode current collector; 12. Positive electrode active layer; 2. Sulfide electrolyte layer; 3. Electrolyte membrane; 4. Negative electrode sheet; 41. Negative electrode current collector; 42. Negative electrode active layer.

[0020] Figure 2 Capacity retention curves for some embodiments and some comparative examples. Detailed Implementation

[0021] This application discloses a solid-state battery and its fabrication method. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this application. The methods and applications of this application have been described through preferred embodiments. Those skilled in the art can obviously modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this application.

[0022] In the description of this application, the list of items connected by the term "at least one of" or other similar terms may mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A and B" means only A; only B; or A and B. In another instance, if items A, B, and C are listed, then the phrase "at least one of A, B, and C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0023] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges, or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. Unless otherwise stated, all embodiments and optional embodiments of this application can be combined with each other to form new technical solutions.

[0024] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0025] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0026] To improve the interfacial contact of solid-state batteries, this application provides a solid-state battery and a method for its fabrication.

[0027] According to a first aspect of this application, a solid-state battery is provided, comprising at least one cell, the cell comprising a positive electrode, a sulfide electrolyte layer, an electrolyte membrane, and a negative electrode stacked sequentially; the negative electrode comprises a negative current collector and a negative active layer disposed on the surface of the negative current collector, the negative active layer comprising a negative active material, a sulfide electrolyte, and a conductive agent; the electrolyte membrane comprises a first polymer and a lithium salt, the thickness of the electrolyte membrane being 1 μm to 10 μm. Exemplarily, the thickness of the electrolyte membrane can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0028] This application introduces an electrolyte film with a thickness of 1μm to 10μm on the negative electrode side of the sulfide solid electrolyte membrane, which helps improve the physical contact state of the solid-solid interface in solid-state batteries. This structure can alleviate the ion transport resistance caused by insufficient interface contact to a certain extent, while enhancing the mechanical support and strength of the sulfide electrolyte layer. In addition, the presence of this polymer electrolyte film also helps reduce the reduction and decomposition of sulfides on the negative electrode side, regulates the ion flow distribution at the interface, buffers the impact of negative electrode expansion on the solid-solid interface contact, and plays a positive role in improving the uniformity of lithium-ion deposition and promoting battery cycle stability.

[0029] In one embodiment of this application, the ratio of the thickness of the sulfide electrolyte layer to the thickness of the electrolyte membrane is 3.5~35:1; and / or, the conductivity of the electrolyte membrane at 15℃~25℃ is greater than 5*10. -5 S / cm. For example, the ratio of the thickness of the sulfide electrolyte layer to the thickness of the electrolyte membrane can be 3.5:1, 5:1, 10:1, 15:1, 20:1, 25:1, 30:1 or 35:1, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0030] In one embodiment of this application, the thickness of the sulfide electrolyte layer is 15 μm to 35 μm. Exemplarily, the thickness of the sulfide electrolyte layer can be 15 μm, 17 μm, 19 μm, 20 μm, 21 μm, 23 μm, 25 μm, 27 μm, 29 μm, 30 μm, 31 μm, 33 μm, or 35 μm, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0031] In one embodiment of this application, the sulfide electrolyte layer includes a sulfide electrolyte and a binder.

[0032] In one embodiment of this application, the sulfide electrolyte includes Thio-LISICON, Li 10 GeP2S 12 Li 10 SnP2S 12 Li₂S-P₂S₅, Li 10 SiP2S 12 , Li2S-Si2S2, Li2S-B2S3, Li (7-a) PS (6-a) M' a At least one of them; wherein, Li (7-a) PS (6-a) M' a In this context, M' includes at least one of Cl, Br, F, or I, and 0.1 ≤ a ≤ 5.9.

[0033] In one embodiment of this application, the mass percentage of the sulfide electrolyte in the sulfide electrolyte layer is 90% to 99.5%. Exemplarily, the mass percentage of the sulfide electrolyte can be 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99%, or 99.5%, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0034] In one embodiment of this application, the binder in the sulfide electrolyte layer includes at least one selected from polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), polyisobutylene (PIB), nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), styrene-butadiene rubber (SBR), styrene-butadiene block copolymer (SBS), hydrogenated styrene-butadiene block copolymer (SEBS), polytetrafluoroethylene (PTFE), and polyethylene oxide (PEO). This application does not impose any particular limitation on the source of the above binder; commercially available products well known to those skilled in the art can be used.

[0035] In one embodiment of this application, the polyvinylidene fluoride (PVDF) used in the sulfide electrolyte layer includes at least one of PVDF5130, PVDF75130, PVDF21216, PVDF6020, and PVDF-HVS900.

[0036] In one embodiment of this application, the poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) used in the sulfide electrolyte layer includes PVDF-LBG (low-adhesion polyvinylidene fluoride) manufactured by Arkema. By adjusting the monomer ratio of vinylidene fluoride to hexafluoropropylene, the cleanliness of the copolymer can be effectively reduced, thereby improving its processability.

[0037] In one embodiment of this application, the first polymer includes polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride, and polyvinylidene fluoride. At least one of hexafluoropropylene or polyphosphorazine; and / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium tetrafluoroborate, lithium hexafluorophosphate, or lithium perchlorate; and / or, the mass ratio of the first polymer to the lithium salt is (3-5):1. This application does not impose any special restrictions on the source of the aforementioned first polymer and lithium salt; commercially available products well known to those skilled in the art can be used. Exemplarily, the mass ratio of the first polymer to the lithium salt can be 3:1, 3.5:1, 4:1, 4.5:1, or 5:1, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0038] In one embodiment of this application, the negative electrode active layer further includes an elastic composite ion conductor material, which comprises an inorganic electrolyte, a second polymer, and a lithium salt. Introducing the elastic composite ion conductor material into the negative electrode sheet, with the inorganic-organic polymer composite electrolyte serving as the interfacial connector between the negative electrode active particles, creates a space charge region at the interface between the polymer and the inorganic electrolyte due to their significant differences in physical and chemical properties. Within this region, the synergistic effect of the two improves lithium-ion transport. The micropores and nanopores of the polymer and the inorganic phase themselves can also serve as lithium-ion transport channels, mitigating the impact of expansion and contraction of the negative electrode active material while further improving interfacial ion conductivity, enhancing the continuity of electrolyte contact, and maintaining stable contact between the electrode and the electrolyte. Furthermore, when the negative electrode active layer includes silicon-based materials, introducing the elastic composite ion conductor material helps mitigate the volume changes of the silicon-based materials.

[0039] In one embodiment of this application, the inorganic electrolyte comprises 1% to 10% by mass in the elastic composite ionic conductor material; and / or, the average particle size D50 of the inorganic electrolyte is 10 nm to 200 nm. Exemplarily, the mass percentage of the inorganic electrolyte can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc.; the average particle size D50 of the inorganic electrolyte can be 10 nm, 30 nm, 50 nm, 70 nm, 90 nm, 100 nm, 110 nm, 130 nm, 150 nm, 170 nm, 190 nm, or 200 nm, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable. If the inorganic electrolyte particles are too small, the transport interface will excessively affect the conductivity; if they are too large, they may generate cutting forces in the composite system, leading to a decrease in the strength of the composite electrolyte.

[0040] In one embodiment of this application, the inorganic electrolyte includes at least one of lithium aluminum titanium phosphate (LATP), lithium lanthanum zirconium oxide (LLZO), lithium lanthanum titanium oxide (LLTO), lithium aluminum germanium phosphate (LAGP), and lithium zirconium oxide (Li2ZrO3).

[0041] In one embodiment of this application, the chemical formula of the lithium aluminum titanium phosphate electrolyte (LATP) is Li. (1+b) Al b Ti (2-b) (PO4)3, where 0 < b < 1. For example, b can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 or 0.9, etc., but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0042] In one embodiment of this application, the chemical formula of lithium lanthanum zirconium oxide is Li7La3Zr2O. 12 .

[0043] In one embodiment of this application, the chemical formula of lithium lanthanum titanium oxide is Li7La3Zr2O. 12 .

[0044] In one embodiment of this application, lithium aluminum germanium phosphate (LAGP) has the chemical formula Li. (1+c) Al c Ge (2-c) (PO4)3, where 0 ≤ c ≤ 0.5. For example, c can be 0.1, 0.2, 0.3, 0.4 or 0.5, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0045] In one embodiment of this application, the second polymer includes polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride, and polyvinylidene fluoride. The second polymer and lithium salt are selected from at least one of hexafluoropropylene, polyphosphorazine, and their derivatives; and / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium tetrafluoroborate, lithium hexafluorophosphate, or lithium perchlorate; and / or, the mass ratio of the second polymer to the lithium salt is (3-4):1. This application does not impose any special restrictions on the source of the aforementioned second polymer and lithium salt; commercially available products well known to those skilled in the art can be used. Exemplarily, the mass ratio of the second polymer to the lithium salt can be 3:1, 3.1:1, 3.3:1, 3.5:1, 3.7:1, 3.9:1, or 4:1, etc., but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0046] In one embodiment of this application, the negative electrode active material includes at least one of nano-silicon, silicon carbide, silicon suboxide, and graphite.

[0047] In one embodiment of this application, the negative electrode active material further includes at least one of tin or its alloy, magnesium or its alloy.

[0048] In one embodiment of this application, the conductive agent in the negative electrode active layer includes at least one of zero-dimensional, one-dimensional, or two-dimensional conductive agents. Based on their spatial geometric characteristics, conductive agents can be classified as zero-dimensional, one-dimensional, and two-dimensional. Zero-dimensional conductive agents, as nanoscale point-like units, can effectively fill the interparticle gaps of the active material; one-dimensional conductive agents have a high aspect ratio linear or fibrous structure, which can extend within the electrode and bridge long distances, thereby establishing a stable long-range conductive framework. Two-dimensional conductive agents, with their ultra-thin sheet-like morphology, can achieve large-area electronic contact.

[0049] In one embodiment of this application, in the negative electrode active layer, the zero-dimensional conductive agent includes conductive carbon black (SP) and / or acetylene black (AB); and / or, the one-dimensional conductive agent includes carbon nanotubes (CNTs) and / or vapor-grown carbon fibers (VGCF); and / or, the two-dimensional conductive agent includes graphene. This application does not impose any special restrictions on the source of the above-mentioned conductive agents; commercially available products well known to those skilled in the art can be used.

[0050] In one embodiment of this application, in the negative electrode active layer, the negative electrode active material: sulfide electrolyte: conductive agent: elastic composite ionic conductor material is calculated by mass ratio as follows: 50%~85%: 3%~48.8%: 0.1%~2%: 1%~10%.

[0051] In one embodiment of this application, the positive electrode includes a positive electrode active layer, the positive electrode active layer includes a positive electrode active material; and / or, the positive electrode active material includes LiNi. x Co y M z O2, wherein M includes at least one of Mn, Al, Zr, Ti, V, Mg, Fe, or Mo, 0≤x<1, 0≤y<1, 0≤z<1, and x+y+z=1; and / or, the positive electrode active material further includes a coating layer disposed on its surface, the coating layer including at least one of Li2TiO3, LiNbO3, Li3BO3, Li2ZrO3, LiCoO3, LiPO3, Li2MnO4, Al(PO3)3, La(PO3)3, and NaPO3. This application does not impose any special restrictions on the source of the materials used for the above-mentioned positive electrode active particles and coating layer; commercially available products well known to those skilled in the art can be used. In particular, this application can reduce the interfacial reaction between sulfides and positive electrode particles by introducing a coating layer on the surface of the positive electrode active material.

[0052] In one embodiment of this application, the thickness of the coating layer is 1 nm to 10 nm. Exemplarily, the thickness of the coating layer can be 1 nm, 2 nm, 3 nm, 4 nm, 5 nm, 6 nm, 7 nm, 8 nm, 9 nm or 10 nm, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0053] In one embodiment of this application, the positive electrode active layer further includes a solid electrolyte, a conductive agent, and a binder.

[0054] In one embodiment of this application, the solid electrolyte in the positive electrode active layer includes Thio-LISICON and Li 10 GeP2S 12 Li 10 SnP2S 12 Li₂S-P₂S₅, Li 10 SiP2S 12 , Li2S-Si2S2, Li2S-B2S3, Li (7-d) PS (6-d) M” d At least one of them; wherein, Li (7-d) PS (6-d) M” d In this context, "M" includes at least one of Cl, Br, F, or I, and 0.1 ≤ d ≤ 5.9.

[0055] In one embodiment of this application, the conductive agent in the positive electrode active layer includes at least one of a zero-dimensional conductive agent, a one-dimensional conductive agent, or a two-dimensional conductive agent.

[0056] In one embodiment of this application, the zero-dimensional conductive agent in the positive electrode active layer includes conductive carbon black (SP) and / or acetylene black (AB); and / or, the one-dimensional conductive agent includes carbon nanotubes (CNTs) and / or vapor-grown carbon fibers (VGCF); and / or, the two-dimensional conductive agent includes graphene. This application does not impose any special restrictions on the source of the above-mentioned conductive agents; commercially available products well known to those skilled in the art can be used.

[0057] In one embodiment of this application, the binder in the positive electrode active layer includes at least one of polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP), polyisobutylene (PIB), nitrile butadiene rubber (NBR), hydrogenated nitrile butadiene rubber (HNBR), styrene-butadiene rubber (SBR), styrene-butadiene block copolymer (SBS), hydrogenated styrene-butadiene block copolymer (SEBS), polytetrafluoroethylene (PTFE), and polyethylene oxide (PEO).

[0058] In one embodiment of this application, the polyvinylidene fluoride (PVDF) used in the positive electrode active layer includes at least one of PVDF5130, PVDF75130, PVDF21216, PVDF6020, and PVDF-HVS900.

[0059] In one embodiment of this application, in the positive electrode active layer, the ratio of positive electrode active material: solid electrolyte: conductive agent: binder is 70%~90%: 8.8%~29.8%: 0.1%~3%: 0.1%~5% by mass percentage.

[0060] In one embodiment of this application, the projected area of ​​the positive electrode is smaller than the projected area of ​​the negative electrode on the projection plane along the thickness direction; and / or, the minimum distance between any point on the projection outline boundary line of the positive electrode and the projection outline boundary line of the negative electrode is D, where 0.1 mm ≤ D ≤ 2.6 mm.

[0061] In addition to ensuring unobstructed ion pathways within each component, all-solid-state batteries require close contact between components during operation, such as between the positive electrode layer and the electrolyte membrane, and between the electrolyte membrane and the negative electrode layer. However, since the area of ​​the negative electrode active layer is proportionally larger than that of the positive electrode active layer, shear forces exist after stacking, affecting the battery's cycle stability. This application, by introducing an electrolyte membrane and controlling the distance between the positive and negative electrode sheets, can further reduce the shear forces after stacking and improve the structural stability of the solid-state battery.

[0062] According to a second aspect of this application, this application provides a method for preparing a solid-state battery as described above. The method includes the following steps: S1. Premixing a positive electrode sheet, a negative electrode sheet, an electrolyte membrane, and a sulfide electrolyte layer; wherein the premixing material for the positive electrode sheet is obtained by mixing a positive active material, a sulfide electrolyte, a conductive agent, a binder, and a solvent; the premixing material for the negative electrode sheet is obtained by mixing a negative active material, a sulfide electrolyte, a conductive agent, and a solvent; the premixing material for the electrolyte membrane is obtained by mixing a first polymer, a lithium salt, and a solvent; the premixing material for the sulfide electrolyte layer is obtained by mixing a sulfide electrolyte, a binder, and a solvent; S2. Coating the premixing material of the positive electrode sheet onto the surface of a positive current collector to prepare a positive electrode sheet; S3. Coating the premixing material of the sulfide electrolyte layer onto the surface of a base layer, and after drying... S4. A sulfide electrolyte layer is formed on the surface of the base layer; S5. The premix of the electrolyte membrane is coated on the surface of the sulfide electrolyte layer and then dried to form an electrolyte membrane on the surface of the sulfide electrolyte layer, thus obtaining a composite electrolyte membrane; S6. When the negative electrode active layer does not include an elastic composite ion conductor material, the premix of the negative electrode sheet is used as a negative electrode slurry; when the negative electrode active layer includes an elastic composite ion conductor material, an elastic composite ion conductor slurry is prepared, and then the elastic composite ion conductor slurry is added to the premix of the negative electrode sheet for mixing to obtain a negative electrode slurry; the negative electrode slurry is coated on the surface of the negative electrode current collector to obtain a negative electrode sheet; S7. The negative electrode sheet and the composite electrolyte membrane are composited by hot rolling to bond the electrolyte membrane to the negative electrode sheet; S8. A solid-state battery is obtained through an assembly process.

[0063] The preparation method provided in this application combines optimized electrolyte membrane preparation processes with battery structure design to synergistically improve the overall performance and process adaptability of solid-state batteries. The polymer electrolyte membrane coated on the sulfide electrolyte layer not only improves the success rate of hot rolling composite with less binder, but also forms a protective layer between the sulfide electrolyte layer and the negative electrode, reducing interfacial side reactions during charging. It buffers the impact of negative electrode volume expansion on the structure. During hot rolling, the first polymer in the electrolyte membrane melts and fills the interfacial pores, increasing the interfacial bonding strength, thereby strengthening the structural integrity of the sulfide electrolyte layer, improving its bonding stability with the edge of the positive electrode active layer, buffering cyclic stress, reducing interfacial impedance, and promoting uniform lithium-ion deposition. The hot rolling process is equivalent to transferring the electrolyte membrane and sulfide electrolyte layer onto the negative electrode sheet. During hot rolling, the substrate detaches from the surface of the sulfide electrolyte layer, forming a composite negative electrode sheet containing both the electrolyte membrane and the sulfide electrolyte layer. In contrast, traditional solid-state batteries have a rigid solid-solid interface, and their preparation methods improve the interfacial contact through hydrostatic pressing, but this suffers from low efficiency and difficulty in commercial production. The preparation method provided in this application further simplifies the cell assembly process through the aforementioned hot rolling transfer technology. It not only exhibits good compatibility with existing production line equipment but also helps suppress the reduction and decomposition of the electrolyte-negative electrode interface under low pressure. This preparation process eliminates the need for isostatic pressing before assembly. Therefore, the preparation method provided in this application not only improves the performance of solid-state batteries but also balances preparation efficiency and cost, thereby facilitating the commercialization of all-solid-state batteries.

[0064] In one embodiment of this application, the solvent includes at least one of alkane or derivative solvents, cycloalkanes or derivative solvents, carbonate solvents, carboxylic acid ester solvents, ether solvents, ketone solvents, amide solvents, and aqueous solvents.

[0065] In one embodiment of this application, the alkane or its derivative solvent includes at least one of dichloromethane, n-hexane, n-heptane, n-decane, or dodecane.

[0066] In one embodiment of this application, the cycloalkane or derivative solvent includes at least one of toluene, xylene, monochlorobenzene, or 1,3,5-trimethylbenzene.

[0067] In one embodiment of this application, the carboxylic acid ester solvent includes isobutyl isobutyrate.

[0068] In one embodiment of this application, the ether solvent includes anisole.

[0069] In one embodiment of this application, the ketone solvent includes at least one of 2,4-dimethyl-3-pentanone and cyclohexanone.

[0070] In one embodiment of this application, at least one of the amide solvents N,N-dimethylformamide and N-methylformamide is used.

[0071] In one embodiment of this application, in type S3, the base layer is one of aluminum foil, PTFE board, glass, ceramic, stainless steel board, and polymer release film.

[0072] In one embodiment of this application, in S4, the drying process is to dry at 50°C to 80°C for 24 to 72 hours in a vacuum environment; and / or, in S6, the hot rolling process is to apply pressure of 10 MPa to 200 MPa at 80°C to 120°C.

[0073] In one embodiment of this application, after the assembly process in step S7, an isostatic pressing treatment is also required. The isostatic pressing treatment can further improve the interfacial bonding strength between the layers.

[0074] In one embodiment of this application, the isostatic pressing pressure is 100 MPa to 600 MPa, the temperature is 30°C to 90°C, and the holding time is 1 minute to 60 minutes. More preferably, the isostatic pressing pressure is 200 MPa to 500 MPa, the temperature is 50°C to 80°C, and the holding time is 5 minutes to 30 minutes.

[0075] To further illustrate this application, the following experimental groups are described in detail. Unless otherwise specified, all raw materials used in the following experimental groups of this application are commercially available.

[0076] Experimental group 1 Example 1 In this embodiment, the raw materials required for preparing the positive electrode, sulfide electrolyte layer, electrolyte membrane, and negative electrode are weighed according to the formula shown in Table 1. The mass percentages in the table refer to the mass content of the corresponding component in the corresponding structure. In the elastic composite ionic conductor material, the mass ratio of PVDF-HFP to lithium bis(trifluoromethanesulfonyl)imide is 3.5:1, and the content of the inorganic electrolyte is 3% by mass percentage.

[0077] Table 1. Raw materials required for preparing solid-state batteries in Example 1

[0078] This embodiment prepares a solid-state battery according to the following steps: S1. Prepare premixes for the positive electrode, the negative electrode, the electrolyte membrane, and the sulfide electrolyte layer according to the formulations shown in Table 1; S2. The premixed material of the positive electrode is coated on the surface of carbon-coated aluminum foil, and after drying and rolling, the positive electrode is obtained (die-cut to 15*10cm). S3. Subsequently, a premix of aluminum foil as the base material and a sulfide electrolyte layer coated on its surface is taken and dried to form a sulfide electrolyte layer on the aluminum foil surface. S4. After coating the premix of polymer electrolyte membrane onto the surface of the sulfide electrolyte layer, it is dried at 70°C under vacuum for 50 hours to form an electrolyte membrane on the surface of the sulfide electrolyte layer, thus obtaining a composite electrolyte membrane; wherein, the conductivity of the formed electrolyte membrane at 25°C is 2.1*10 -3 S / cm; S5. Prepare a paste for the elastic composite ion conductor, and then add the paste for the elastic composite ion conductor to the premix of the negative electrode sheet for mixing to obtain a negative electrode paste; coat the negative electrode paste onto the surface of carbon-coated copper foil to obtain a negative electrode sheet (double-sided); wherein, the NP ratio of the positive electrode sheet to the negative electrode sheet is 1.3. S6. The composite electrolyte membrane prepared in S4 is laminated onto the surfaces of both sides of the double-sided negative electrode prepared in S5 under hot rolling conditions of 200 MPa and 80°C (with the polymer electrolyte membrane facing the negative electrode side) to obtain a negative electrode sheet, which is then die-cut into 15.3*10.3 cm. After the negative electrode sheet is laminated by rolling, the aluminum foil in step S3 will detach from the surface of the sulfide electrolyte layer, so that both sides of the formed negative electrode sheet are laminated with a composite structure of polymer electrolyte membrane and sulfide electrolyte layer. S7. Perform a stacking process, take the positive electrode sheet prepared in step S2 and composite it onto the surface of the sulfide electrolyte membrane in the composite structure of step S6 to form a unit cell with a double negative electrode in the middle and a single positive electrode on both sides; then continue to complete the assembly process such as electrode tab welding and encapsulation, and perform isostatic electrostatic treatment (300MPa, 60℃ for 10 minutes) to complete the cell preparation; wherein, the thickness of the positive electrode active layer of the positive electrode sheet is 75μm, the thickness of the sulfide electrolyte layer is 30μm, and the thickness of the polymer electrolyte membrane is 5μm (that is, the thickness ratio of the sulfide electrolyte layer to the electrolyte membrane is 6:1).

[0079] Example 2 This embodiment prepares a solid-state battery with reference to the formulation and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that the thickness ratio of the sulfide electrolyte layer to the electrolyte membrane is 2:1 (total thickness is 15 μm, the thickness of the sulfide electrolyte layer is 10 μm, and the thickness of the polymer electrolyte membrane is 5 μm). Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0080] Example 3 This embodiment prepares a solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that the thickness ratio of the sulfide electrolyte layer to the electrolyte membrane is 35:1 (total thickness is 36 μm, the thickness of the sulfide electrolyte layer is 35 μm, and the thickness of the electrolyte membrane is 1 μm). Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0081] Example 4 This embodiment prepares a solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that the thickness ratio of the sulfide electrolyte layer to the electrolyte membrane is 45:1 (total thickness is 46 μm, the thickness of the sulfide electrolyte layer is 45 μm, and the thickness of the electrolyte membrane is 1 μm). Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0082] Example 5 This embodiment prepares a solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that, in preparing the solid-state battery, an equal mass part of Li2ZrO3 with D50=10nm is used to replace LATP in the elastic composite ionic conductor material. Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0083] Example 6 This embodiment prepares a solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that, in preparing the solid-state battery, an equal mass part of LLZO with D50=200nm is used to replace LATP in the elastic composite ionic conductor material. Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0084] Example 7 This embodiment prepares a solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that no elastic composite ion conductor material (silicon-carbon:Li6PS5Cl:VGCF:SBR=66%:28%:1%:5%) is added to the negative electrode active layer when preparing the solid-state battery. Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0085] Example 8 This embodiment prepares a solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that no inorganic electrolyte is added to the elastic composite ionic conductor material when preparing the solid-state battery. Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0086] Example 9 This embodiment prepares a solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that, in preparing the solid-state battery, an equal mass fraction of inorganic electrolyte LATP is used to replace the elastic composite ionic conductor material (i.e., the first polymer and lithium salt are not added). Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0087] Example 10 This embodiment prepares a solid-state battery with reference to the formula and method provided in Example 1 of Experimental Group 1. The difference between this embodiment and Example 1 of Experimental Group 1 is that the D50 of the inorganic electrolyte LATP in the elastic composite ionic conductor material is 260 nm when preparing the solid-state battery. Apart from the above differences, the operation steps for preparing the solid-state battery in this embodiment are strictly consistent with those in Example 1 of Experimental Group 1.

[0088] Comparative Example 1 This comparative example prepares a solid-state battery using the formula and method provided in Example 1 of Experimental Group 1. The difference between this comparative example and Example 1 of Experimental Group 1 is that no electrolyte membrane is used when preparing the solid-state battery. Apart from the above differences, the operation steps for preparing the solid-state battery in this comparative example are strictly consistent with those in Example 1 of Experimental Group 1.

[0089] Comparative Example 2 This comparative example prepares a solid-state battery using the formula and method provided in Example 1 of Experimental Group 1. The difference between this comparative example and Example 1 of Experimental Group 1 is that the thickness of the electrolyte membrane is 15 μm when preparing the solid-state battery. Apart from the above differences, the operation steps for preparing the solid-state battery in this comparative example are strictly consistent with those in Example 1 of Experimental Group 1.

[0090] Comparative Example 3 This comparative example prepares a solid-state battery using the formula and method provided in Example 1 of Experimental Group 1. The difference between this comparative example and Example 1 of Experimental Group 1 is that the electrolyte membrane in this comparative example is formed solely by the inorganic electrolyte LATP during the preparation of the solid-state battery. Apart from the above differences, the operation steps for preparing the solid-state battery in this comparative example are strictly consistent with those in Example 1 of Experimental Group 1.

[0091] Test Example 1 1. Test Object Solid-state batteries prepared in Examples 1-10 and Comparative Examples 1-3 of Experimental Group 1 were used as test subjects.

[0092] 2. Testing Methods (1) Cyclic performance test: The test pressure of the solid-state battery (laminated battery) was controlled at 3.5 MPa, and the test temperature was controlled at 35℃. The battery was charged to the cutoff voltage of 4.25V with a constant current of 0.33C, and then discharged to the cutoff voltage of 2V with a constant current of 0.33C. The cycle test was repeated for 200 complete cycles. The discharge capacity of the first cycle was recorded as C1, and the discharge capacity of the 200th cycle was recorded as C2. 200 The capacity retention rate after 200 cycles can be obtained by the formula shown in equation (1).

[0093] Equation (1) 3. Test Results and Analysis The test results for this test case are shown in Table 2.

[0094] Compared to Example 1, the capacity retention rates of the solid-state battery provided in Comparative Example 1 (which did not have an electrolyte membrane), the solid-state battery provided in Comparative Example 2 (which had an excessively thick electrolyte membrane, 15 μm), and the solid-state battery provided in Comparative Example 3 (which had an electrolyte membrane formed solely by inorganic nanomaterials) all decreased significantly to 65.2%, 64.4%, and NG (not up to standard), respectively. This further confirms the crucial role of the electrolyte membrane in the structure and battery performance, as well as the direct impact of its thickness and material composition on the performance of solid-state batteries.

[0095] Based on the test data from Examples 1-4, it can be seen that a reasonable thickness ratio between the electrolyte membrane and the sulfide electrolyte layer helps to further improve solid-solid interface contact, enhance ion transport uniformity, and alleviate interfacial side reactions, thereby effectively maintaining cycle stability.

[0096] In Examples 5 and 6, inorganic electrolytes with different nanoparticle sizes were used, achieving 88.2% and 87.5% respectively, indicating that inorganic electrolytes are applicable to oxides such as LATP, LLZO, LLTO, LAGP, and Li2ZrO3.

[0097] Comparing the data from Examples 1 and 7-9 shows that when no elastic composite ion conductor material or inorganic nanomaterials, the second polymer, and lithium salt were added, the capacity retention decreased to 66.5%, 68.1%, and 69.3%, respectively. This indicates that the synergistic introduction of inorganic nanomaterials, the second polymer, and lithium salt into the elastic composite ion conductor material can significantly contribute to enhancing interfacial mechanical support, regulating ion current distribution, and suppressing reductive decomposition.

[0098] Furthermore, in Example 9, the capacity retention rate was 72% when the particle size of the inorganic electrolyte was increased to 260 nm, further illustrating that the optimization of the inorganic electrolyte particle size also affects the interfacial conductivity and structural stability of the solid-state battery.

[0099] In summary, this application achieves a synergistic effect in improving interfacial contact, reducing impedance, and uniform lithium-ion deposition by introducing and controlling the thickness of the electrolyte membrane, using elastic composite ion conductor materials in the negative electrode, and optimizing the process. This not only significantly improves the cycle stability of solid-state batteries but also takes into account the feasibility of the fabrication process and equipment compatibility, thus achieving a balance between performance improvement and the needs of commercial production.

[0100] Table 2. Test results provided in Test Example 1

[0101] The above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A solid-state battery, characterized in that, The solid-state battery includes at least one cell, and the cell includes a positive electrode, a sulfide electrolyte layer, an electrolyte membrane, and a negative electrode stacked in sequence. The negative electrode sheet includes a negative electrode current collector and a negative electrode active layer disposed on the surface of the negative electrode current collector. The negative electrode active layer includes a negative electrode active material, a sulfide electrolyte, and a conductive agent. The electrolyte membrane comprises a first polymer and a lithium salt, and the thickness of the electrolyte membrane is 1 μm to 10 μm.

2. The solid-state battery as described in claim 1, characterized in that, The ratio of the thickness of the sulfide electrolyte layer to the thickness of the electrolyte membrane is 3.5~35:1; and / or, the conductivity of the electrolyte membrane at 15℃~25℃ is greater than 5*10⁻⁶. -5 S / cm.

3. The solid-state battery as described in claim 1, characterized in that: The first polymer includes polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride, and polyvinylidene fluoride. At least one of hexafluoropropylene or polyoxopropylidene; And / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium tetrafluoroborate, lithium hexafluorophosphate, or lithium perchlorate; And / or, the mass ratio of the first polymer to the lithium salt is (3-5):

1.

4. The solid-state battery as described in claim 1, characterized in that, The negative electrode active layer also includes an elastic composite ion conductor material, which comprises an inorganic electrolyte, a second polymer, and a lithium salt.

5. The solid-state battery as described in claim 4, characterized in that: In the elastic composite ionic conductor material, the inorganic electrolyte accounts for 1% to 10% by mass. And / or, the average particle size D50 of the inorganic electrolyte is 10 nm to 200 nm.

6. The solid-state battery as described in claim 4, characterized in that: The second polymer includes polyethylene glycol dimethacrylate, polymethyl methacrylate, polyvinylidene fluoride, and polyvinylidene fluoride. At least one of hexafluoropropylene, polyphosphorazine and its derivatives; And / or, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide, lithium trifluoromethanesulfonylimide, lithium chloride, lithium tetrafluoroborate, lithium tetrafluoroborate, lithium hexafluorophosphate, or lithium perchlorate; And / or, the mass ratio of the second polymer to the lithium salt is (3-4):

1.

7. The solid-state battery as described in claim 1, characterized in that: The positive electrode sheet includes a positive electrode active layer, and the positive electrode active layer includes a positive electrode active material; And / or, the positive electrode active material includes LiNi x Co y M z O2, wherein M includes a combination of at least one of Mn, Al, Zr, Ti, V, Mg, Fe or Mo, 0≤x<1, 0≤y<1, 0≤z<1, and x+y+z=1; And / or, the positive electrode active material further includes a coating layer disposed on its surface, the coating layer including at least one of Li2TiO3, LiNbO3, Li3BO3, Li2ZrO3, LiCoO3, LiPO3, Li2MnO4, Al(PO3)3, La(PO3)3, and NaPO3.

8. The solid-state battery as described in claim 1, characterized in that: On the projection plane along the thickness direction, the projected area of ​​the positive electrode is smaller than the projected area of ​​the negative electrode. And / or, the minimum distance between any point on the projection outline boundary line of the positive electrode and the projection outline boundary line of the negative electrode is D, where 0.1 mm ≤ D ≤ 2.6 mm.

9. A method for preparing a solid-state battery as described in any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: S1. Premixes for the positive electrode, the negative electrode, the electrolyte membrane, and the sulfide electrolyte layer are prepared respectively; wherein, the premix for the positive electrode is obtained by mixing a positive electrode active material, a sulfide electrolyte, a conductive agent, a binder, and a solvent; the premix for the negative electrode is obtained by mixing a negative electrode active material, a sulfide electrolyte, a conductive agent, and a solvent; the premix for the electrolyte membrane is obtained by mixing a first polymer, a lithium salt, and a solvent; and the premix for the sulfide electrolyte layer is obtained by mixing a sulfide electrolyte, a binder, and a solvent. S2. The positive electrode sheet is prepared by coating the premix of the positive electrode sheet onto the surface of the positive electrode current collector; S3. The premix of the sulfide electrolyte layer is applied to the surface of the base layer, and after drying, the sulfide electrolyte layer is formed on the surface of the base layer; S4. The premix of the electrolyte membrane is coated onto the surface of the sulfide electrolyte layer and then dried to form the electrolyte membrane on the surface of the sulfide electrolyte layer, thus obtaining a composite electrolyte membrane. S5. When the negative electrode active layer does not include the elastic composite ion conductor material, the premix of the negative electrode sheet is used as the negative electrode slurry; when the negative electrode active layer includes the elastic composite ion conductor material, a slurry of the elastic composite ion conductor is prepared, and then the slurry of the elastic composite ion conductor is added to the premix of the negative electrode sheet for mixing to obtain the negative electrode slurry; the negative electrode slurry is coated on the surface of the negative electrode current collector to obtain the negative electrode sheet; S6. The negative electrode sheet and the composite electrolyte membrane are bonded together by hot rolling process, so that the electrolyte membrane and the negative electrode sheet are attached; S7. The solid-state battery is obtained through the assembly process.

10. The preparation method according to claim 9, characterized in that: In S4, the drying process involves drying at 50°C to 80°C in a vacuum environment for 24 to 72 hours. And / or, in S6, the hot roll pressing conditions are 10MPa~200MPa and 80℃~120℃.

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