Solid-state electrolyte membrane, method for preparing the same, and battery

Abstract

The application relates to the technical field of batteries, in particular to a solid-state electrolyte film, a preparation method thereof and a battery. The solid-state electrolyte film comprises a first solid-state electrolyte layer, a second solid-state electrolyte layer and a modification layer located between the first solid-state electrolyte layer and the second solid-state electrolyte layer; wherein the first solid-state electrolyte layer comprises an inorganic solid-state electrolyte; the second solid-state electrolyte layer comprises an organic solid-state electrolyte; and the modification layer comprises an organic polymer and a carbon-based material. In the solid-state electrolyte film provided by the application, the modification layer located between the first solid-state electrolyte layer and the second solid-state electrolyte layer not only further improves the ion conductivity of the battery, but also enhances the interface stability inside the battery, effectively reduces the resistance and charge accumulation of the interlayer interface, thereby prolonging the cycle life of the battery and improving the safety of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of batteries, and in particular to a solid electrolyte membrane, a preparation method thereof, and a battery. Background Art

[0002] With the rapid development of energy storage technology, solid-state batteries have attracted considerable attention due to their high energy density, long cycle life, and excellent safety performance. A core component of solid-state batteries is the solid electrolyte, which conducts lithium ions between the positive and negative electrodes while isolating electrons to prevent battery short circuits. Compared to traditional liquid electrolytes, solid-state electrolytes have higher thermal and chemical stability, significantly improving battery safety.

[0003] However, the development of solid-state electrolytes faces numerous challenges. On the one hand, inorganic solid-state electrolytes such as sulfides, oxides, and perovskites, while offering high ionic conductivity, often suffer from poor interfacial compatibility with electrode materials and mechanical brittleness. On the other hand, organic solid-state electrolytes such as polymer electrolytes, while offering good flexibility and interfacial compatibility, have relatively low ionic conductivity and are prone to electrochemical decomposition at high voltages.

[0004] Therefore, there is an urgent need to provide a solution to improve the performance and stability of solid-state batteries. Summary of the Invention

[0005] In view of this, the present invention aims to solve at least one of the technical problems in the related art to a certain extent. To this end, the present invention provides a solid electrolyte membrane and a preparation method thereof and a battery, which can improve the performance and stability of solid-state batteries.

[0006] In order to solve the above technical problems, this application is implemented as follows:

[0007] According to one aspect of the present application, an embodiment of the present application provides a solid electrolyte membrane, the solid electrolyte membrane comprising: a first solid electrolyte layer, a second solid electrolyte layer, and a finishing layer located between the first solid electrolyte layer and the second solid electrolyte layer;

[0008] Wherein, the first solid electrolyte layer comprises an inorganic solid electrolyte;

[0009] The second solid electrolyte layer includes an organic solid electrolyte;

[0010] The modified layer includes an organic polymer and a carbon-based material.

[0011] In addition, the solid electrolyte membrane according to the present application may also have the following additional technical features:

[0012] In some embodiments, the organic polymer in the modification layer includes at least one of polyvinylidene fluoride, polyethylene oxide, or polyterephthalimide.

[0013] In some embodiments, the carbon-based material includes at least one of graphite fluoride, graphyne, carbon fiber, or carbon nanotubes.

[0014] In some embodiments, the mass ratio of the organic polymer to the carbon-based material is (50-95): (5-50).

[0015] In some embodiments, the thickness of the modified layer is 5 μm to 50 μm.

[0016] In some embodiments, the inorganic solid electrolyte includes at least one of a sulfide solid electrolyte or an oxide solid electrolyte; the inorganic solid electrolyte is preferably selected from at least one of an LGPS sulfide solid electrolyte or an LLZTO oxide solid electrolyte.

[0017] In some embodiments, the first solid electrolyte layer further includes a first binder.

[0018] In some embodiments, the mass ratio of the inorganic solid electrolyte to the first binder is (60-95): (5-40).

[0019] In some embodiments, the thickness of the first solid electrolyte layer is 10 μm to 100 μm.

[0020] In some embodiments, the sulfide solid electrolyte includes Li 10-2x M x GeP2S 12 , 0.1≤x≤0.5; the M includes at least one of Ba or Ca.

[0021] In some embodiments, the sulfide solid electrolyte includes Li 10-3y Al y GeP2S 12 , 0.02≤y≤0.3.

[0022] In some embodiments, the oxide solid electrolyte includes Li 6.4 La3Zr 1.76 Al 0.24 O 12 、Li 6.4 La3Zr 1.8 Ga 0.2 O 12 or Li 6.4 La3Zr1.2 Ga 0.6 O 12 At least one of .

[0023] In some embodiments, the organic solid electrolyte includes a polymer solid electrolyte and a lithium salt.

[0024] In some embodiments, the mass ratio of the polymer solid electrolyte to the lithium salt is (2-5):1.

[0025] In some embodiments, the polymer solid electrolyte includes at least one of a polymer, a blend system derived from the polymer, or a copolymer system derived from the polymer; the polymer is selected from at least one of polyoxyalkylene, polymethyl methacrylate, or polyacrylonitrile.

[0026] In some embodiments, the polyalkylene oxide comprises polyethylene oxide and / or polypropylene oxide.

[0027] In some embodiments, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), or lithium perchlorate (LiClO4).

[0028] In some embodiments, the second solid electrolyte layer further includes a second binder.

[0029] In some embodiments, the mass ratio of the polymer to the second binder is (50-90): (10-50).

[0030] In some embodiments, the thickness of the second solid electrolyte layer is 20 μm to 200 μm.

[0031] According to another aspect of the present application, an embodiment of the present application provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0032] preparing a first solid electrolyte layer, a modified layer and a second solid electrolyte layer respectively;

[0033] The first solid electrolyte layer, the modified layer and the second solid electrolyte layer are stacked in sequence to obtain a solid electrolyte membrane.

[0034] In some embodiments, the method for preparing the modified layer includes: mixing an organic polymer and a carbon-based material, drying, and grinding to obtain a composite material of the organic polymer and the carbon-based material;

[0035] The composite material of the organic polymer and the carbon-based material is pressed into a sheet to obtain a modified layer.

[0036] In some embodiments, the composite material of the organic polymer and the carbon-based material has a particle size of 5 nm to 100 nm.

[0037] In some embodiments, the tableting pressure is 10 MPa to 100 MPa.

[0038] According to another aspect of the present application, an embodiment of the present application provides a solid-state battery, which includes the aforementioned solid-state electrolyte membrane or the solid-state electrolyte membrane prepared according to the aforementioned method.

[0039] The implementation of the technical solution of the present invention has at least the following beneficial effects:

[0040] In the embodiments of this application, the modified layer of the solid electrolyte membrane provided herein comprises an organic polymer and a carbon-based material. This combination of organic polymer and carbon-based material achieves a fusion and complementarity of organic and inorganic materials. The organic polymer provides the modified layer with excellent film-forming properties and good compatibility with other electrode materials, while the carbon-based material provides efficient ion transport channels for the modified layer.

[0041] In summary, the modified layer between the first and second solid electrolyte layers not only further improves the battery's ionic conductivity but also enhances the interfacial stability within the battery, effectively reducing the resistance and charge accumulation at the interfacial surface between the layers, thereby extending the battery's cycle life and improving its safety. The composite material formed by combining organic polymers and carbon-based materials can enhance the interfacial compatibility between the first and second solid electrolyte layers, reduce interfacial resistance, and improve the battery's ionic conductivity efficiency.

[0042] Additional aspects and advantages of the present application will be given in part in the following description and in part will become obvious from the following description or will be learned through practice of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Shown is a schematic diagram of the structure of a solid electrolyte membrane provided in Example 1 of the present invention.

[0044] 1-first solid electrolyte layer;

[0045] 2-modification layer;

[0046] 3-Second solid electrolyte layer. DETAILED DESCRIPTION

[0047] The present application will be further described below with reference to specific examples. It should be understood that these examples are only used to illustrate the present application and are not intended to limit the scope of the present application.

[0048] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range or the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0049] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0050] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0051] Unless otherwise specified, all steps of the present application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), indicating that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0052] Unless otherwise specified, the terms "include" and "comprising" used in this application may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0053] Existing solid-state batteries contain inorganic solid electrolytes such as sulfide, oxide and perovskite systems. Although they have high ion conductivity, they often have problems such as poor interface compatibility with electrode materials and large mechanical brittleness. Organic solid electrolytes such as polymer polymer electrolytes have good flexibility and interface compatibility, but their ion conductivity is relatively low and they are prone to electrochemical decomposition under high voltage. The relevant technology provides a strategy for constructing a double-layer solid electrolyte structure, which can simultaneously improve the performance and safety of solid-state batteries. However, due to the differences in ion conduction mechanism and efficiency between inorganic solid electrolytes and organic solid electrolytes, the above strategy still has the problem of difficulty in achieving effective bonding between the two layers of electrolytes and poor ion conduction.

[0054] In view of this, an embodiment of the present application provides a solid electrolyte membrane, the solid electrolyte membrane comprising: a first solid electrolyte layer, a second solid electrolyte layer, and a modification layer located between the first solid electrolyte layer and the second solid electrolyte layer;

[0055] Wherein, the first solid electrolyte layer includes an inorganic solid electrolyte;

[0056] The second solid electrolyte layer includes an organic solid electrolyte;

[0057] The modification layer includes organic polymers and carbon-based materials.

[0058] In the solid electrolyte membrane of the present embodiment, the modified layer comprises an organic polymer and a carbon-based material. This combination of organic polymer and carbon-based material achieves a fusion and complementarity of organic and inorganic materials. The organic polymer provides the modified layer with excellent film-forming properties and good compatibility with other electrode materials, while the carbon-based material provides efficient ion transport pathways for the modified layer.

[0059] In summary, the modified layer between the first and second solid electrolyte layers not only further improves the battery's ionic conductivity but also enhances the interfacial stability within the battery, effectively reducing the resistance and charge accumulation at the interfacial surface between the layers, thereby extending the battery's cycle life and improving its safety. The composite material formed by combining organic polymers and carbon-based materials can enhance the interfacial compatibility between the first and second solid electrolyte layers, reduce interfacial resistance, and improve the battery's ionic conductivity efficiency.

[0060] In some embodiments, the organic polymer in the modification layer includes at least one of polyvinylidene fluoride, polyethylene oxide, or polyterephthalimide. For example, the organic polymer in the modification layer can be polyvinylidene fluoride, polyethylene oxide, or preferably polyvinylidene fluoride. Organic polymers have good film-forming properties and compatibility with electrode materials, helping to reduce interfacial resistance and improve the battery's ion conduction efficiency, thereby improving the interfacial compatibility between the first solid electrolyte layer and the second solid electrolyte layer.

[0061] In some embodiments, the carbon-based material in the modified layer includes at least one of graphite fluoride, graphyne, carbon fiber, or carbon nanotubes. By way of example, the carbon-based material in the modified layer can be graphite fluoride, graphyne, or carbon fiber, preferably graphite fluoride. Combining the carbon-based material with the organic polymer can reduce interfacial resistance and improve the battery's ion conduction efficiency, enabling more efficient ion transport during charge and discharge.

[0062] Preferably, the organic polymer used in the modified layer is polyvinylidene fluoride, and the carbon-based material is graphite fluoride. Compared to other types of organic polymers and carbon-based materials, the combination of polyvinylidene fluoride (PVDF) and graphite fluoride complements each other, achieving a fusion and complementarity of organic and inorganic materials. PVDF provides excellent film-forming properties and compatibility with electrode materials, while graphite fluoride provides efficient ion transport channels and good conductivity. This combination helps reduce resistance and charge accumulation at the interlayer interface, improving the battery's ion conduction efficiency, extending the battery's cycle life, and enhancing battery safety.

[0063] In some embodiments, the mass ratio of the organic polymer to the carbon-based material is (50~95):(5~50). As an example, the mass ratio of the organic polymer to the carbon-based material can be 50:5, 60:40, 70:30, 80:20, 95:5, etc., and of course it can also be other values ​​within the above range, which is not limited here. When the mass ratio of the organic polymer to the carbon-based material is too small, it may cause uneven internal structure of the modified layer, affecting the transmission efficiency of ions in the modified layer, and thus may reduce the ion conductivity and interface stability of the battery; when the mass ratio of the organic polymer to the carbon-based material is too large, it may fill or block the ion transmission channel, thereby reducing the ion transmission rate in the modified layer, which may also affect the ion conductivity and interface stability of the battery.

[0064] In some embodiments, the thickness of the modified layer is 5μm to 50μm. As an example, the thickness of the modified layer can be 5μm, 15μm, 25μm, 35μm, 45μm, 50μm, etc., and of course it can also be other values ​​within the above range, which is not limited here. If the thickness of the modified layer is too small, it may not provide sufficient ion conduction channels and interface stability enhancement effects; if the thickness of the modified layer is too large, then the excessively thick modified layer may cause the battery to generate more heat during the charge and discharge process, affecting the thermal stability and safety of the battery.

[0065] In some embodiments, the inorganic solid electrolyte includes at least one of a sulfide solid electrolyte or an oxide solid electrolyte. As an example, the inorganic solid electrolyte can be a sulfide solid electrolyte or an oxide solid electrolyte.

[0066] In some embodiments, the inorganic solid electrolyte is preferably selected from at least one of LGPS sulfide solid electrolytes or LLZTO oxide solid electrolytes. The oxide solid electrolyte may also be a perovskite electrolyte, such as an LLTO-type solid electrolyte or a NASICON-type solid electrolyte.

[0067] In some embodiments, the first solid electrolyte layer further includes a first binder. Specifically, the first solid electrolyte layer includes an inorganic solid electrolyte and a first binder. The first binder can be a conventional binder used in solid electrolyte membranes in the art. As an example, the binder in the solid electrolyte layer may optionally include one or more of polyvinyl alcohol (PVA), polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, nitrile rubber, polyamide, polyethyleneimine, or polyimide. Preferably, the binder is PVA.

[0068] However, the present application is not limited to these binders, and other conventional materials or improved materials that can be used as binders in batteries can also be used. The above-mentioned binders can be used alone or in combination of two or more.

[0069] In some embodiments, the mass ratio of the inorganic solid electrolyte to the first binder is (60-95):(5-40). As an example, the mass ratio of the inorganic solid electrolyte to the first binder can be 60:40, 70:30, 80:40, 95:5, etc., and of course other values ​​within the above range are also possible and are not limited here.

[0070] In some embodiments, the thickness of the first solid electrolyte layer is 10μm~100μm. As an example, the thickness of the first solid electrolyte layer can be 10μm, 30μm, 60μm, 80μm, 100μm, etc., and of course it can also be other values ​​within the above range, which is not limited here. If the thickness of the first solid electrolyte layer is too large, it may cause the ion transmission path inside the battery to become longer, increase the resistance to ion transmission, and thus reduce the ion conductivity of the battery. If the thickness of the first solid electrolyte layer is too small, then the too thin solid electrolyte layer may not be able to effectively isolate the positive and negative electrodes, increasing the risk of battery short circuit.

[0071] In some embodiments, the sulfide solid electrolyte includes Li 10-2x M x GeP2S 12 , 0.1≤x≤0.5; M includes at least one of Ba and Ca. As an example, M may be Ba or Ca.

[0072] In some embodiments, the sulfide solid electrolyte includes Li 10-3y Al y GeP2S 12 , 0.02≤y≤0.3.

[0073] In some embodiments, the oxide solid electrolyte includes Li 6.4 La3Zr 1.76 Al 0.24 O 12 、Li6.4 La3Zr 1.8 Ga 0.2 O 12 or Li 6.4 La3Zr 1.2 Ga 0.6 O 12 . As an example, the oxide solid-state electrolyte can be Li 6.4 La3Zr 1.76 Al 0.24 O 12 . As an example, the oxide solid-state electrolyte can be Li 6.4 La3Zr 1.8 Ga 0.2 O 12 .

[0074] In some embodiments, the organic solid-state electrolyte includes a polymer solid-state electrolyte and a lithium salt. It is noted that the organic solid-state electrolyte includes the polymer solid-state electrolyte, or includes the polymer solid-state electrolyte and the lithium salt. The lithium salt can increase the lithium ion transport rate, and the specific amount of addition can be adjusted by those skilled in the art according to the demand of the lithium ion transport rate, which can further improve the performance of the final battery.

[0075] In some embodiments, the mass ratio of the polymer solid-state electrolyte and the lithium salt is (2-5): 1. As an example, the mass ratio of the polymer solid-state electrolyte and the lithium salt can be 2:1, 3:1, 4:1, 5:1, etc., and of course can also be other values within the above range, which are not limited herein.

[0076] In some embodiments, the polymer solid-state electrolyte includes at least one of a polymer, a blending system derived from the polymer, or a copolymer system derived from the polymer. In the present application, the polymer is selected from at least one of a polyalkylene oxide, a polymethyl methacrylate, or a polyacrylonitrile. As an example, the polymer can be a polyalkylene oxide, and can be a polymethyl methacrylate.

[0077] In some embodiments, the polyalkylene oxide includes a polyethylene oxide and / or a polypropylene oxide. As an example, the polyalkylene oxide can be a polyethylene oxide, and can be a polypropylene oxide.

[0078] In some embodiments, the lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide LiTFSI, lithium hexafluorophosphate LiPF6, or lithium perchlorate LiClO4. As an example, the lithium salt can be lithium bis(trifluoromethanesulfonyl)imide LiTFSI, can be lithium hexafluorophosphate LiPF6, and can be lithium perchlorate LiClO4.

[0079] In some embodiments, the second solid electrolyte layer further includes a second binder. Specifically, the second solid electrolyte layer comprises an organic solid electrolyte and a second binder. The second binder can be a conventional binder used in solid electrolyte membranes in the art. For example, the binder in the solid electrolyte layer may include one or more of polyvinyl alcohol (PVA), polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, nitrile rubber, polyamide, polyethyleneimine, or polyimide. Preferably, the binder is PVA.

[0080] However, the present application is not limited to these binders, and other conventional materials or improved materials that can be used as binders in batteries can also be used. The above-mentioned binders can be used alone or in combination of two or more.

[0081] In some embodiments, the mass ratio of the polymer to the second binder is (50-90):(10-50). As examples, the mass ratio of the polymer to the second binder is 50:50, 60:40, 70:30, 80:40, 90:10, etc., and other values ​​within the above range are also possible and are not limited here.

[0082] In some embodiments, the thickness of the second solid electrolyte layer is 20μm~200μm. As an example, the thickness of the second solid electrolyte layer can be 20μm, 50μm, 100μm, 150μm, 200μm, etc., and of course it can also be other values ​​within the above range, which is not limited here. If the thickness of the second solid electrolyte layer is too large, it may cause the ion transmission path inside the battery to become longer, increase the resistance to ion transmission, and thus reduce the ion conductivity of the battery. If the thickness of the second solid electrolyte layer is too small, then the too thin solid electrolyte layer may not be able to effectively isolate the positive and negative electrodes, increasing the risk of battery short circuit.

[0083] In some embodiments, the first binder and the second binder each independently include at least one of polyvinyl alcohol (PVA), polyvinylidene fluoride, polytetrafluoroethylene, polyacrylic acid, styrene-butadiene rubber, nitrile rubber, polyamide, polyethyleneimine, or polyimide.

[0084] Thus, based on the above scheme, a solid electrolyte membrane is provided. By setting a modification layer between the inorganic solid electrolyte layer and the organic solid electrolyte layer, the problem of difficulty in achieving effective bonding and poor ion conduction between the two electrolyte layers is solved. The modification layer includes an organic polymer and a carbon-based material. The combination of the organic polymer and the carbon-based material realizes the fusion and complementarity of organic-inorganic materials. The organic polymer has good film-forming properties and compatibility with electrode materials, which helps to reduce the interface resistance and improve the ion conduction efficiency of the battery, thereby improving the interface compatibility between the first solid electrolyte layer and the second solid electrolyte layer. The combination of carbon-based materials and organic polymers can reduce the interface resistance, improve the ion conduction efficiency of the battery, and enable the battery to more efficiently perform ion migration during the charging and discharging process.

[0085] The modified layer between the first and second solid electrolyte layers not only further improves the battery's ionic conductivity but also enhances the interfacial stability within the battery, effectively reducing resistance and charge accumulation at the interlayer interface, thereby extending the battery's cycle life and improving its safety. Furthermore, the composite material formed by combining organic polymers and carbon-based materials can enhance the interfacial compatibility between the first and second solid electrolyte layers, reducing interfacial resistance and improving the battery's ionic conductivity.

[0086] Based on the same inventive concept, an embodiment of the present application provides a method for preparing a solid electrolyte membrane, comprising the following steps:

[0087] preparing a first solid electrolyte layer, a modified layer and a second solid electrolyte layer respectively;

[0088] The first solid electrolyte layer, the modified layer and the second solid electrolyte layer are stacked in sequence to obtain a solid electrolyte membrane.

[0089] In this application, a modified layer is used to improve the poor bonding and ionic conductivity between the first and second solid electrolyte layers, thereby effectively improving the mechanical and electrical performance of the battery. Furthermore, the method provided in this application offers low preparation costs and a simple process, making it suitable for large-scale application.

[0090] It should be understood that all the features and advantages described above for the “solid electrolyte membrane” are also applicable to the “method for preparing the solid electrolyte membrane” and will not be described in detail here.

[0091] In some embodiments, the method for preparing the modified layer includes: mixing an organic polymer and a carbon-based material, drying, and grinding to obtain a composite material of the organic polymer and the carbon-based material;

[0092] The composite material of the organic polymer and the carbon-based material is pressed into a sheet to obtain a modified layer.

[0093] In some embodiments, the particle size of the composite material of the organic polymer and the carbon-based material is 5nm~100nm. As an example, the particle size of the composite material of the organic polymer and the carbon-based material can be 5nm, 25nm, 45nm, 65nm, 85nm, 100nm, etc., and of course it can also be other values ​​within the above range, which is not limited here. If the particle size of the composite material of the organic polymer and the carbon-based material is too small, then the particle size is too small, which may cause uneven dispersion of the composite material, or affect the film-forming properties of the modified layer, thereby affecting the ion conductivity and interface stability of the battery; if the particle size of the composite material of the organic polymer and the carbon-based material is too large, then the particle size is too large, which may cause uneven distribution of the composite material in the modified layer, affecting the continuity of the ion transmission channel, thereby reducing the ion conduction efficiency of the battery.

[0094] In some embodiments, the pressure during tableting is 10MPa~100MPa. As an example, the pressure during tableting can be 10MPa, 30MPa, 50MPa, 70MPa, 90MPa, 100MPa, etc., and of course it can also be other values ​​within the above range, which are not limited here. If the pressure during tableting is too small, then the pressure is too small, which may cause the modified layer laminate to be loose, with pores or cracks, affecting the ion conductivity and interface stability of the modified layer, thereby reducing the cycle life and safety of the battery; if the pressure during tableting is too large, then the pressure is too large, which may cause the composite material to be over-compacted, destroying the structure of the ion transport channel, or making the modified layer too dense, affecting the migration of lithium ions, thereby reducing the ion conduction efficiency and performance of the battery.

[0095] The modified layer prepared by the above method is composed of an organic polymer and a carbon-based material. It combines the excellent film-forming properties and compatibility of the organic polymer with the efficient ion transport pathways provided by the carbon-based material. By controlling the particle size of the organic polymer and carbon-based material composite (5nm-100nm) and the pressure during tableting (10MPa-100MPa), the structure and properties of the modified layer can be precisely controlled. This allows the thickness of the modified layer to be adjusted within a range of 5μm-50μm.

[0096] In some embodiments, preparing the first solid electrolyte layer includes cutting the inorganic solid electrolyte layer to meet the structure of battery assembly.

[0097] In some embodiments, the preparation of the second solid electrolyte layer includes: dissolving a polymer solid electrolyte in an organic solvent, applying the solution to the surface of the substrate by a casting, spin coating or spraying process, forming a solid electrolyte film after drying, and obtaining the second solid electrolyte layer after cutting to meet the structure of battery assembly.

[0098] In some embodiments, the preparation of the second solid electrolyte layer includes: dissolving a polymer solid electrolyte and a lithium salt in an organic solvent, applying the solution to the surface of the substrate by a casting, spin coating or spraying process, forming a solid electrolyte film after drying, and obtaining the second solid electrolyte layer after cutting to meet the structure of the battery assembly.

[0099] Based on the above, the present invention combines an organic polymer and a carbon-based material, drying and grinding them to obtain a composite material of the organic polymer and carbon-based material; the composite material of the organic polymer and carbon-based material is then pressed into a sheet to obtain a modified layer. This modified layer achieves the fusion and complementarity of organic and inorganic materials, has a controllable particle size and thickness, significantly improves the battery's ion conductivity and interfacial stability, extends the battery's cycle life, enhances battery safety, and reduces interfacial resistance.

[0100] Furthermore, by stacking the first solid electrolyte layer, the modified layer, and the second solid electrolyte layer in sequence, a solid electrolyte membrane can be obtained, and the preparation process is simple. The modified layer located between the first and second solid electrolyte layers not only further improves the battery's ionic conductivity, but also enhances the internal interface stability of the battery, effectively reducing the resistance and charge accumulation at the interlayer interface, thereby extending the battery's cycle life and improving its safety. Furthermore, the composite material formed by combining the organic polymer and the carbon-based material can enhance the interfacial compatibility between the first and second solid electrolyte layers, reduce interfacial resistance, and improve the battery's ionic conduction efficiency.

[0101] Based on the same inventive concept, an embodiment of the present application provides a solid-state battery, which includes the aforementioned solid-state electrolyte membrane or a solid-state electrolyte membrane prepared according to the aforementioned method.

[0102] Since the solid-state battery uses the solid electrolyte membrane of this embodiment, it can achieve effective combination of the inorganic solid electrolyte layer and the organic solid electrolyte layer, and can also improve the ion conductivity, so the battery has higher cycle stability and higher capacity.

[0103] Optionally, the solid-state battery includes the provided solid-state electrolyte membrane. In addition, the solid-state battery may also include other structures known in the art, such as a shell, which is not limited to this.

[0104] Example

[0105] Hereinafter, the embodiments of the present application will be described. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. Reagents, materials, or instruments used that do not specify the manufacturer are all conventional products that can be purchased commercially.

[0106] Example 1

[0107] The first solid electrolyte layer: sulfide solid electrolyte LGPS (Li 10 GeP2S 12 ), thickness of 50 μm;

[0108] Second solid electrolyte layer: Polyethylene oxide (PEO) is selected as the polymer solid electrolyte and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is used as the ion conductor. The thickness is 100 μm.

[0109] The mass ratio of polyethylene oxide (PEO) to lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is 50:50.

[0110] Modifying layer: Graphite fluoride (GFNs) were uniformly dispersed in a dimethylformamide (DMF) solution of polyvinylidene fluoride (PVDF) (the mass ratio of GFNs to PVDF was 20:80). Ultrasonic dispersion was used to ensure uniform distribution of the GFNs. The dispersed solution was vacuum-dried at 80°C for 24 hours to remove the solvent. The dried composite was ground to obtain a GFNs-PVDF composite powder. This powder was then filled into a mold and compacted using a hydraulic press at 50 MPa to form a 25μm-thick modified layer.

[0111] The first solid electrolyte layer, the modified layer and the second solid electrolyte layer are stacked in sequence to obtain a solid electrolyte membrane.

[0112] Example 2

[0113] The first solid electrolyte layer: the oxide solid electrolyte LLZTO (Li7La3Zr2O 12 ), thickness of 30 μm;

[0114] Second solid electrolyte layer: Polymethyl methacrylate (PMMA) is used as the polymer solid electrolyte and lithium perchlorate (LiClO4) is used as the ion conductor, with a thickness of 150μm;

[0115] The mass ratio of polymethyl methacrylate (PMMA) to lithium perchlorate (LiClO4) is 90:10;

[0116] Modifying layer: Graphite fluoride (GFNs) were uniformly dispersed in a dimethylformamide (DMF) solution of polyvinylidene fluoride (PVDF) (the mass ratio of GFNs to PVDF was 30:70). Ultrasonic dispersion was used to ensure uniform distribution of the GFNs. The dispersed solution was vacuum-dried at 80°C for 24 hours to remove the solvent. The dried composite was then ground to obtain a GFNs-PVDF composite powder. This powder was then filled into a mold and compacted using a hydraulic press at 50 MPa to form a 25μm-thick modified layer.

[0117] The first solid electrolyte layer, the modified layer and the second solid electrolyte layer are stacked in sequence to obtain a solid electrolyte membrane.

[0118] Example 3

[0119] The difference between Example 3 and Example 1 is that the organic polymer in the modification layer of Example 3 is polyterephthalimide, and the carbon-based material is graphyne. The rest is the same as Example 1.

[0120] Example 4

[0121] The difference between Example 4 and Example 1 is that the carbon-based material in the modification layer of Example 4 is carbon fiber, and the rest is the same as Example 1.

[0122] Example 5

[0123] The difference between Example 5 and Example 1 is that the mass ratio of graphite fluoride to polyvinylidene fluoride in the modification layer of Example 5 is 50:50, and the rest is the same as Example 1.

[0124] Example 6

[0125] The difference between Example 6 and Example 1 is that the thickness of the modified layer in Example 6 is 5 μm, and the rest is the same as Example 1.

[0126] Example 7

[0127] The only difference between Example 7 and Example 1 is that the thickness of the modified layer in Example 7 is 50 μm, and the rest is the same as Example 1.

[0128] Comparative Example 1

[0129] The only difference between Comparative Example 1 and Example 1 is that there is no modification layer in Comparative Example 1, and the rest is the same as Example 1.

[0130] Performance Testing

[0131] The solid electrolyte membranes prepared in the above embodiments and comparative examples were prepared into button batteries, specifically including: ensuring that the water and oxygen contents therein were always maintained below 0.01 ppm in a glove box filled with argon; and preparing a dual solid electrolyte all-solid-state battery in the order of negative electrode-first solid electrolyte layer (inorganic solid electrolyte) / modified layer / second solid electrolyte layer (organic solid electrolyte) / lithium iron phosphate (positive electrode).

[0132] The prepared dual solid-state electrolyte all-solid-state battery was placed on the Blue Electric battery tester, all the full batteries were placed at room temperature, and the Blue Electric battery test system was used to test its constant current charge and discharge long cycle test within the voltage range of 2.5~4.0V (charging cut-off voltage is 4.0V, discharging cut-off voltage is 2.5V).

[0133] The long cycle test process is as follows: ① let it stand for 5 minutes, ② charge at a constant current of 0.2C to 4.0V, ③ let it stand for 5 minutes, ④ discharge at a constant current of 0.2C to 2.5V, ⑤ cycle steps 1) to 4) for 300 cycles, and record the discharge capacity at the 300th cycle.

[0134] The test results are shown in Table 1.

[0135] Table 1

[0136]

[0137] As shown in Table 1, the battery of Example 1 was able to cycle 300 times under 0.2C conditions with a discharge capacity of 155.3 mAh / g, demonstrating good cycle performance and capacity performance. The battery of Example 2 was able to cycle 300 times under 0.2C conditions with a discharge capacity of 150.4 mAh / g. Although the number of cycles was slightly less than that of Example 1, the discharge capacity was still high, demonstrating good performance.

[0138] The battery in Comparative Example 1 achieved a discharge capacity of 142.6 mAh / g after 300 cycles at 0.2C. Compared with Examples 1 and 2, the battery in Comparative Example 1 lacks a modified layer, resulting in poor ion conduction and difficulty in achieving effective bonding between the two electrolyte layers. The lack of a modified layer in Comparative Example 1 also resulted in very poor long-term cycle performance and capacity performance, indicating that the lack of a modified layer hinders effective bonding between the two electrolyte layers and poor ion conduction.

[0139] Compared to Example 1 (polyvinylidene fluoride / graphite fluoride), the discharge capacities of Example 3 (poly(terephthalimide) / graphene) and Example 4 (carbon fiber) decreased. This suggests that different combinations of organic polymers and carbon-based materials affect battery performance, and the material combination in Example 1 may be superior.

[0140] In Example 5 (graphite fluoride / polyvinylidene fluoride mass ratio of 50:50), the discharge capacity decreased compared to Example 1 (20:80). This suggests that increasing the proportion of carbon-based materials may be detrimental to improving battery performance, as excessive carbon-based materials may affect interfacial stability.

[0141] Compared to Example 1 (25 μm), the discharge capacities of Examples 6 (5 μm modified layer thickness) and 7 (50 μm modified layer thickness) decreased. This indicates that the thickness of the modified layer affects battery performance; either too thin or too thick a modified layer can reduce battery performance.

[0142] Parts of the present invention that are not described in detail are well known to those skilled in the art.

[0143] The basic principles of the present invention have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in the present invention are merely illustrative and non-limiting, and should not be construed as necessarily possessed by each embodiment of the present invention. Furthermore, the specific details disclosed above are provided for illustrative purposes and to facilitate understanding, and are not intended to be limiting. These details do not necessarily limit the present invention to being implemented using these specific details.

[0144] It should be noted that the terms "and / or" or " / " used herein are merely a description of an association relationship between associated objects, indicating that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist at the same time, and B exists alone. The singular forms "a," "the," and "the" used in the embodiments of the present invention and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0145] In the detailed description and claims, a list of items connected by the terms "at least one of," "at least one of," "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, the phrase "at least one of A and B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, 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 include a single element or multiple elements. Item B may include a single element or multiple elements. Item C may include a single element or multiple elements.

[0146] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A solid electrolyte membrane, characterized in that The solid electrolyte membrane comprises: a first solid electrolyte layer, a second solid electrolyte layer and a modification layer located between the first solid electrolyte layer and the second solid electrolyte layer; Wherein, the solid electrolyte in the first solid electrolyte layer is an inorganic solid electrolyte; The solid electrolyte in the second solid electrolyte layer is an organic solid electrolyte; The modified layer includes an organic polymer and a carbon-based material; The organic polymer in the modification layer includes at least one of polyvinylidene fluoride, polyethylene oxide or polyterephthalimide; The carbon-based material includes at least one of graphite fluoride, graphyne, carbon fiber or carbon nanotube; The mass ratio of the organic polymer to the carbon-based material is (50-95): (5-50); The thickness of the modified layer is 5 μm to 50 μm.

2. The solid electrolyte membrane according to claim 1, characterized in that The inorganic solid electrolyte includes at least one of a sulfide solid electrolyte or an oxide solid electrolyte; And / or, the first solid electrolyte layer further includes a first binder; The mass ratio of the inorganic solid electrolyte to the first binder is (60-95): (5-40); And / or, the thickness of the first solid electrolyte layer is 10 μm to 100 μm.

3. The solid electrolyte membrane according to claim 2, characterized in that The sulfide solid electrolyte includes Li 10-2x M x GeP2S 12 , 0.1≤x≤0.5; The M includes at least one of Ba and Ca; And / or, the sulfide solid electrolyte includes Li 10-3y Al y GeP2S 12 , 0.02≤y≤0.

3.

4. The solid electrolyte membrane according to claim 2, characterized in that The oxide solid electrolyte includes Li 6.4 La3Zr 1.76 Al 0.24 O 12 、Li 6.4 La3Zr 1.8 Ga 0.2 O 12 or Li 6.4 La3Zr 1.2 Ga 0.6 O 12 At least one of .

5. The solid electrolyte membrane according to claim 1, wherein The organic solid electrolyte includes a polymer solid electrolyte and a lithium salt; The mass ratio of the polymer solid electrolyte to the lithium salt is (2-5):1; The polymer solid electrolyte comprises at least one of a polymer, a blend system derived from the polymer, or a copolymer system derived from the polymer; the polymer is selected from at least one of polyoxyalkylene, polymethyl methacrylate, or polyacrylonitrile; The polyoxyalkylenes include polyethylene oxide and / or polypropylene oxide; The lithium salt includes at least one of lithium bis(trifluoromethanesulfonyl)imide LiTFSI, lithium hexafluorophosphate LiPF6 or lithium perchlorate LiClO4; And / or, the second solid electrolyte layer further includes a second binder; The mass ratio of the polymer to the second binder is (50-90): (10-50); And / or, the thickness of the second solid electrolyte layer is 20 μm to 200 μm.

6. The method for preparing a solid electrolyte membrane according to any one of claims 1 to 5, wherein: The following steps are involved: preparing a first solid electrolyte layer, a modified layer and a second solid electrolyte layer respectively; The first solid electrolyte layer, the modified layer and the second solid electrolyte layer are stacked in sequence to obtain a solid electrolyte membrane.

7. The method for preparing a solid electrolyte membrane according to claim 6, wherein: The preparation method of the modified layer comprises: mixing an organic polymer and a carbon-based material, drying and grinding to obtain a composite material of the organic polymer and the carbon-based material; The composite material of the organic polymer and the carbon-based material is pressed into a sheet to obtain a modified layer.

8. The method for preparing a solid electrolyte membrane according to claim 7, wherein: The particle size of the composite material of the organic polymer and the carbon-based material is 5 nm to 100 nm; And / or, the pressure during tableting is 10 MPa to 100 MPa.

9. A solid-state battery, characterized in that: The solid-state battery comprises the solid electrolyte membrane according to any one of claims 1 to 5 or the solid electrolyte membrane prepared by the method according to any one of claims 6 to 8.

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