An organic-inorganic composite solid electrolyte membrane, a preparation method therefor, and an application thereof

Abstract

The application provides an organic-inorganic composite solid electrolyte film and a preparation method and application thereof. The solid electrolyte film can improve the stability to a positive electrode by using an organic-inorganic composite electrolyte layer therein, and can improve the performance of a lithium metal battery when applied to the lithium metal battery using a high-voltage positive electrode material. Meanwhile, the thickness of the solid electrolyte film is equivalent to that of a porous film as a base material, and the solid electrolyte film of the application has good strength due to the porous film as a support, and can meet the purpose of long-term use. After assembling a battery by using the above-mentioned solid electrolyte film, the asymmetry can meet the requirements of positive and negative electrodes at the same time, and can significantly improve the cycle performance of a secondary battery.

Description

Technical Field

[0001] This invention belongs to the field of secondary battery technology, specifically relating to an organic-inorganic composite solid electrolyte membrane, its preparation method, and its application. Background Technology

[0002] Due to the high theoretical specific capacity of lithium metal (3860 mAh g⁻¹) -1 The low redox potential (-3.040V compared to the standard hydrogen electrode) and high capacity of nickel-manganese electrode have made it a highly sought-after anode material for high-energy-density batteries. Matching a high-voltage cathode and a high-capacity anode with a suitable electrolyte is one way to achieve high energy density. However, several issues hinder the development of lithium metal batteries in liquid electrolytes. This is mainly because nickel-manganese electrode materials often require high operating voltages, which traditional liquid electrolytes often cannot meet, potentially leading to electrolyte decomposition. Furthermore, during cycling, liquid electrolytes can cause non-uniform lithium deposition / stripping on the lithium metal anode, resulting in uncontrolled lithium dendrite growth, severe battery capacity decay, and a series of safety issues.

[0003] To address this issue, researchers have employed various methods, including using electrolyte additives, 3D current collector designs, and advanced separators. While these strategies can improve the performance of lithium metal batteries to some extent, the problem of reaction between the liquid electrolyte and lithium metal remains.

[0004] Replacing liquid electrolytes with solid electrolytes is an effective strategy to address the aforementioned safety issues. Solid electrolytes can be classified into three main categories: inorganic solid electrolytes, polymer electrolytes, and organic-inorganic composite electrolytes formed by combining inorganic solid electrolytes and polymer electrolytes. Inorganic solid electrolytes have high mechanical strength and can withstand high operating voltages, effectively suppressing lithium dendrite punctures generated during cycling. However, insufficient contact between the inorganic solid electrolyte and the cathode material leads to a large interfacial resistance, resulting in battery capacity decay and reduced lifespan. Furthermore, thin inorganic solid electrolytes are easily broken, which limits their application to some extent. Ether polymer electrolytes are the most widely studied type of polymer electrolyte. Their molecular chains possess a certain degree of flexibility, solving the problem of large interfacial resistance between the electrolyte and the electrode, and exhibiting good stability against metallic lithium. CN112002941 mentions in-situ copolymerization of 1,3-dioxolane and tetrahydrofuran into a polypropylene separator to prepare an ether gel polymer electrolyte. However, this ether gel polymer electrolyte exhibits rapid capacity decay when used in high-voltage battery systems. To avoid capacity decay of ether polymer electrolytes, CN112018427 proposes using an ether gel polymer electrolyte layer on the negative electrode side and an ester gel polymer electrolyte layer on the positive electrode side, enabling its application in high-voltage battery systems. This is because ether polymers are prone to degradation in the presence of transition metals such as cobalt and nickel in high-voltage positive electrode materials, making ether polymer electrolytes unsuitable for high-voltage positive electrode materials. Organic-inorganic composite solid electrolytes combine the advantages of inorganic solid electrolytes and polymer electrolytes, possessing the high strength and high ionic conductivity of inorganic solid electrolytes and the flexibility and ductility of polymer electrolytes, making them an important direction in solid electrolyte research. Furthermore, current solid electrolyte membranes are typically prepared using methods such as high-temperature sintering, hot pressing, calendering, or casting, with thicknesses usually exceeding 100 μm, which is detrimental to improving the energy density of solid-state lithium-ion batteries. When the thickness is reduced to below 50 μm, the strength is very low, making it difficult to meet the mechanical performance requirements of automated processing, and the fragmentation of solid electrolyte membranes poses safety hazards. Therefore, ultra-thin, high-strength solid electrolytes that are stable to high-voltage cathode materials are urgently needed in the industry. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the inventors of this application discovered that when an inorganic solid electrolyte with a high decomposition voltage is introduced into an ether polymer electrolyte, the resulting organic-inorganic composite solid electrolyte exhibits a high decomposition voltage, which can improve the interfacial stability with high-voltage cathode materials. This suggests its potential application in lithium metal batteries using high-voltage ternary cathode materials. Based on this, the present invention provides an organic-inorganic composite solid electrolyte membrane, its preparation method, and its application. This organic-inorganic composite solid electrolyte membrane is characterized by its ultra-thinness, high strength, and stability at the interface with both positive and negative electrode materials. Its application in lithium metal batteries using high-voltage cathode materials can improve the performance of lithium metal batteries.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A solid electrolyte membrane includes a porous membrane and an organic-inorganic composite electrolyte layer on a first surface of the porous membrane. The porous membrane contains a polymer electrolyte. The organic-inorganic composite electrolyte includes a lithium salt, an ether polymer, and an inorganic solid electrolyte. The polymer electrolyte includes a lithium salt and an ether polymer. The ether polymer is formed by ring-opening polymerization of a cyclic ether compound.

[0008] According to the present invention, the solid electrolyte membrane has an asymmetric structure, the solid electrolyte membrane having an asymmetric structure includes a porous membrane, an organic-inorganic composite electrolyte layer on a first surface of the porous membrane, and a polymer electrolyte layer on a second surface of the porous membrane opposite to the first surface; the porous membrane contains a polymer electrolyte; the organic-inorganic composite electrolyte includes lithium salt, ether polymer and inorganic solid electrolyte; the polymer electrolyte includes lithium salt and ether polymer; the ether polymer is formed by ring-opening polymerization of cyclic ether compounds.

[0009] According to the present invention, the solid electrolyte membrane has a sandwich structure, which includes a porous membrane, an organic-inorganic composite electrolyte layer on both sides of the porous membrane, and a polymer electrolyte layer inside the porous membrane; the polymer electrolyte includes lithium salt and ether polymer; the ether polymer is formed by ring-opening polymerization of cyclic ether compounds; the organic-inorganic composite electrolyte includes lithium salt, ether polymer and inorganic solid electrolyte.

[0010] According to the present invention, the thickness of the polymer electrolyte layer on the second surface of the porous membrane opposite to the first surface is 0.01 μm to 2 μm, preferably 0.1 μm to 1 μm.

[0011] According to the present invention, the thickness of the organic-inorganic composite electrolyte layer is 0.1 μm to 5 μm, preferably 0.5 μm to 2 μm.

[0012] According to the present invention, the porous membrane is selected from polyolefin membranes (including: dry-stretched PP membranes, dry-stretched biaxially oriented PP membranes, wet-stretched biaxially oriented PE membranes), polyolefin membranes coated with alumina on one or both sides, polyolefin membranes coated with polyvinylidene fluoride on one or both sides, polyolefin membranes coated with alumina / polyvinylidene fluoride composite coating on one or both sides, and polyolefin membranes coated with inorganic solid electrolyte coating on one or both sides, etc.

[0013] In this invention, the porous membrane serves as the carrier of the solid electrolyte membrane. Because polyolefin membranes or coated polyolefin membranes have a thickness of less than 30 μm and very high strength (longitudinal tensile strength greater than 100 MPa), solid electrolyte membranes using these porous membranes as carriers possess the characteristics of being ultra-thin and high-strength.

[0014] According to the present invention, the thickness of the porous membrane is 5 μm to 20 μm, the pore size is 100 nm to 200 nm, and the porosity is 30% to 70%.

[0015] According to the present invention, the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium dioxalate borate, lithium difluorooxalate borate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium perfluorobutyl sulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium aluminate, lithium chloroaluminate, lithium fluorosulfonylimide, lithium chloride, and lithium iodide; preferably, the lithium salt is selected from one or two of lithium difluorooxalate borate, lithium perchlorate, lithium hexafluorophosphate, and lithium tetrafluoroborate.

[0016] According to the present invention, the cyclic ether compound is selected from one or more cyclic ether compounds containing one oxygen, two oxygens, three oxygens or more oxygens.

[0017] According to the present invention, the inorganic solid electrolyte is selected from perovskite-type inorganic solid electrolytes (e.g., Li). 3x La 2 / 3- x TiO3, ATiO3 (A = Ca, Sr, Ba); anti-perovskite inorganic solid electrolytes (e.g., Li2Fe2O3); 1-x Mn x SO); Garnet-type inorganic solid electrolytes (e.g., Li7La3Zr2O) 12 (LLZO), A3B2(XO4)3 (A=Ca, Mg, La, B=Al, Fe, Ga, Ge, Mn, Ni, V, X=Si, Ge, Al)); NASICON type inorganic solid electrolytes (e.g., Li 1+x Al x Ti 2-x (PO4)3(LATP), Li 1+x Alx Ge 2-x (PO4)3 (LAGP), LiM2(PO4)3 (M = Ti, Ge, Zr); LISICON-type inorganic solid electrolytes (e.g., Li 4-x Ge 1-x P x S4(LGPS)) and one or more of the following; preferably, the inorganic solid electrolyte is selected from one or more of LLZO, LGPS, LAGP, LATP and the like.

[0018] According to the present invention, in the organic-inorganic composite electrolyte, the lithium salt has a mass percentage content of greater than 5 wt% and less than or equal to 60 wt%; the ether polymer has a mass percentage content of greater than or equal to 20 wt% and less than or equal to 80 wt%; and the inorganic solid electrolyte has a mass percentage content of greater than 5 wt% and less than or equal to 50 wt%.

[0019] Preferably, in the organic-inorganic composite electrolyte, the lithium salt has a mass percentage content of ≥10wt% and ≤40wt%; the ether polymer has a mass percentage content of ≥40wt% and ≤60wt%; and the inorganic solid electrolyte has a mass percentage content of ≥10wt% and ≤30wt%.

[0020] According to the present invention, in the polymer electrolyte, the mass percentage of the lithium salt is greater than 5 wt% and less than or equal to 60 wt%; the mass percentage of the ether polymer is greater than or equal to 20 wt% and less than or equal to 80 wt%.

[0021] Preferably, in the polymer electrolyte, the lithium salt has a mass percentage content of 10 wt% or more and 40 wt% or less; and the ether polymer has a mass percentage content of 40 wt% or more and 60 wt% or less.

[0022] According to the present invention, the decomposition voltage of the solid electrolyte membrane is 4V to 6V, preferably 4.2V to 4.7V.

[0023] According to the present invention, the conductivity of the solid electrolyte membrane is 1×10⁻⁶. -6 ~9×10 -1 S / cm, preferably 1×10 -5 ~9×10 -2 S / cm.

[0024] According to the present invention, the thickness of the solid electrolyte membrane is 4 μm to 50 μm, preferably 5 μm to 20 μm.

[0025] The present invention also provides a method for preparing the above-mentioned solid electrolyte membrane, the method comprising the following steps:

[0026] (1) Prepare a polymerizable system, wherein the polymerizable system includes lithium salts, cyclic ether compounds and inorganic solid electrolytes;

[0027] (2) The polymerizable system of step (1) is coated onto the first surface of the porous membrane and left to stand. The cyclic ether compounds in the polymerizable system undergo a polymerization reaction to obtain the solid electrolyte membrane with the asymmetric structure.

[0028] Alternatively, (2′) the polymerizable system from step (1) is coated onto both surfaces of the porous membrane and left to stand. The cyclic ether compounds in the polymerizable system undergo a polymerization reaction to obtain the solid electrolyte membrane with the sandwich structure.

[0029] According to the present invention, when a polymerizable system comprising lithium salt, polymerized cyclic ether compound, and inorganic solid electrolyte is coated onto the surface of a porous membrane, the inorganic solid electrolyte is trapped on the surface of the porous membrane. The cyclic ether compound can be prepared into an ether polymer by ring-opening polymerization, which together with the lithium salt and the trapped inorganic solid electrolyte forms an organic-inorganic composite electrolyte mainly composed of inorganic solid electrolyte, forming an organic-inorganic composite electrolyte layer on the surface of the porous membrane. Under the combined action of gravity and capillary force, most of the lithium salt and cyclic ether compound permeate into the interior or interior and other side surface of the porous membrane. The cyclic ether compound can be prepared into an ether polymer by ring-opening polymerization, which forms the polymer electrolyte with the lithium salt in the interior or interior and other side of the porous membrane.

[0030] According to the present invention, in step (1), in the polymerizable system, the mass percentage of the lithium salt is greater than 5 wt% and less than or equal to 60 wt%; the mass percentage of the cyclic ether compound is greater than or equal to 20 wt% and less than or equal to 80 wt%; and the mass percentage of the inorganic solid electrolyte is greater than 0 wt% and less than or equal to 40 wt%.

[0031] Preferably, in the polymerizable system, the lithium salt has a mass percentage content of ≥10 wt% and ≤40 wt%; the cyclic ether compound has a mass percentage content of ≥40 wt% and ≤60 wt%; and the inorganic solid electrolyte has a mass percentage content of ≥10 wt% and ≤30 wt%.

[0032] According to the present invention, in steps (2) and (2'), the coating is selected from at least one of drip coating, blade coating, spin coating, spray coating, and gravure coating.

[0033] According to the present invention, in steps (2) and (2'), the temperature of the settling is -40°C to 60°C; and the settling time is 15 seconds to 300 hours.

[0034] According to the present invention, step (2) specifically includes the following steps:

[0035] The polymerizable system from step (1) is coated onto the first surface of the porous membrane. Under the combined action of gravity and capillary force, some lithium salt and cyclic ether compounds penetrate into the interior of the porous membrane and the second surface opposite to the first surface. The inorganic solid electrolyte in the polymerizable system is trapped on the first surface of the porous membrane. The cyclic ether compounds in the polymerizable system undergo polymerization reaction. After drying, the solid electrolyte membrane is obtained.

[0036] The drying step can remove unpolymerized monomers.

[0037] According to the present invention, step (2') specifically includes the following steps:

[0038] The polymerizable system from step (1) is coated onto the two surfaces of the porous membrane. Some lithium salts and cyclic ether compounds penetrate into the interior of the porous membrane under the combined action of gravity and capillary force. The inorganic solid electrolyte in the polymerizable system is trapped on the two surfaces of the porous membrane. The cyclic ether compounds in the polymerizable system undergo polymerization reaction. After drying, the solid electrolyte membrane is obtained.

[0039] The drying step can remove unpolymerized monomers.

[0040] The present invention also provides a secondary battery, the secondary battery comprising the above-described solid electrolyte membrane.

[0041] According to the present invention, the secondary battery is at least one of a button battery, a stacked battery, and a wound battery. Preferably, the outer packaging of the secondary battery is a soft plastic package or a steel shell package.

[0042] The present invention also provides the application of the above-mentioned solid electrolyte membrane, which can be used to prepare secondary batteries.

[0043] According to the present invention, the secondary battery includes at least one of lithium-ion batteries, lithium-sulfur batteries, lithium-air batteries, and sodium-ion batteries.

[0044] The beneficial effects of this invention are:

[0045] The inventors of this application discovered in their research that mixing lithium salts, small-molecule cyclic ether compounds, and inorganic solid electrolytes yields a polymerizable system. This polymerizable system is then uniformly coated onto one side of a porous membrane (as a substrate) using single-sided coating methods such as drop coating, blade coating, spin coating, spray coating, and gravure coating. The inorganic solid electrolyte in the mixture is trapped on one side of the porous membrane, while most of the lithium salt and small-molecule cyclic ether compounds permeate into the interior of the porous membrane and the other side surface under the combined action of gravity and capillary forces. The small-molecule cyclic ether compounds undergo ring-opening polymerization to form a polymer electrolyte, resulting in an organic-inorganic composite asymmetric solid electrolyte membrane. One surface is an organic-inorganic composite electrolyte dominated by the inorganic solid electrolyte, while the interior of the porous membrane and the other surface contain the polymer electrolyte.

[0046] The inventors also proposed another method, mixing lithium salt, small-molecule cyclic ether compounds, and inorganic solid electrolytes to obtain a polymerizable system. This polymerizable system is then uniformly coated onto both surfaces of a porous membrane (as a substrate) using methods such as drop coating, blade coating, spin coating, spray coating, dip coating, and gravure coating. The inorganic solid electrolyte in the polymerizable system is trapped on both sides of the porous membrane, while most of the lithium salt and small-molecule cyclic ether compounds penetrate into the interior of the porous membrane under the combined action of gravity and capillary forces. The small-molecule cyclic ether compounds undergo ring-opening polymerization to form a polymer electrolyte, resulting in an organic-inorganic composite solid electrolyte membrane with a sandwich structure. The two surfaces are composed of an organic-inorganic composite electrolyte dominated by the inorganic solid electrolyte, while the interior of the porous membrane contains the polymer electrolyte.

[0047] This invention provides an organic-inorganic composite solid electrolyte membrane, its preparation method, and its applications. The organic-inorganic composite solid electrolyte membrane is characterized by its ultra-thinness, high strength, and stability at the positive / negative electrode interface. When applied to lithium metal batteries using high-voltage positive electrode materials, it can improve the performance of lithium metal batteries. Furthermore, the thickness of the solid electrolyte membrane is comparable to that of the porous membrane used as the substrate, and due to the support provided by the porous membrane, the solid electrolyte membrane of this invention possesses excellent strength, meeting the requirements for long-term use. When a battery is assembled using the above-mentioned solid electrolyte membrane, the requirements for both positive and negative electrodes can be simultaneously met, significantly improving the cycle performance of the secondary battery. Attached Figure Description

[0048] Figure 1 This is a diagram showing the first charge and discharge cycle of the asymmetric solid electrolyte membrane used in Example 1 as the electrolyte in a lithium-ion battery.

[0049] Figure 2 The diagram shows the cycle performance of the battery assembled using the asymmetric solid electrolyte membrane in Example 2 as the electrolyte for a lithium-ion battery.

[0050] Figure 3 This is a scanning electron microscope image of the surface of the asymmetric solid electrolyte membrane in Example 1 (organic-inorganic electrolyte layer).

[0051] Figure 4 This is a scanning electron microscope image of the surface of the asymmetric solid electrolyte membrane (polymer electrolyte layer) in Example 1.

[0052] Figure 5 This is a cross-sectional scanning electron microscope image of the asymmetric solid electrolyte membrane in Example 1.

[0053] Figure 6 This is a surface scanning electron microscope (SEM) image of the LLZO inorganic solid electrolyte composite membrane coated on the surface of the PE membrane in Example 4.

[0054] Figure 7 This is a cross-sectional scanning electron microscope image of the LLZO inorganic solid electrolyte composite membrane coated on the surface of the PE membrane in Example 4.

[0055] Figure 8 This is a comparison of the decomposition voltage of the solid electrolyte membrane in Example 4 and Comparative Example 1. Detailed Implementation

[0056] [Cyclic ether compounds]

[0057] The solid electrolyte membrane of the present invention includes polymerized cyclic ether compounds selected from C2 to C3 groups containing at least one oxygen atom. 20 Cycloalkanes (i.e., those with 2-20 carbon atoms in a cyclic structure) or C3-C4 hydrocarbons containing at least one oxygen atom 20 Cyclic alkenes (i.e., cyclic structures with 3-20 carbon atoms) contain at least one carbon-carbon double bond.

[0058] In this invention, the cycloalkane or cycloalkene is a monocyclic, fused (e.g., bicyclic), spirocyclic, or bridged ring; when the cycloalkane or cycloalkene is a spirocyclic or bridged ring and contains two or more oxygen atoms, the oxygen atoms may be on one ring or on multiple rings.

[0059] In this invention, the cyclic ether compounds are selected from C2 to C3 compounds containing at least one oxygen atom. 20 Monocyclic alkanes, preferably selected from C3 to C4 groups containing at least one oxygen atom. 20 Monocyclic alkanes, for example, one of the following Class I compounds:

[0060]

[0061] In this invention, the cyclic ether compounds are selected from C4 to C5 groups containing at least one oxygen atom. 20 Fused cycloalkanes, for example, one of the following Class II compounds:

[0062]

[0063]

[0064] In this invention, the cyclic ether compounds are selected from C4 to C5 groups containing at least one oxygen atom. 20 Bridged cycloalkanes, for example, are one of the following third-class compounds:

[0065]

[0066] In this invention, the cyclic ether compounds are selected from C4 to C5 groups containing at least one oxygen atom. 20 Spirocycloalkanes, for example, one of the following Class IV compounds:

[0067]

[0068]

[0069] In this invention, compounds in which at least one C=C bond in the ring structure of the above four types of compounds is replaced by C=C and is stable are those containing at least one oxygen atom in the C3-C series. 20 Cyclic olefins are a preferred type of cyclic ether compound in this invention.

[0070] In this invention, when the cycloalkane or cycloalkene is a monocyclic or fused ring, one or more R1 groups may be substituted on the carbon atoms of the ring; when the cycloalkane or cycloalkene is a bridged ring, one or more R1 groups may be substituted on the non-bridged ring carbon atoms; when the cycloalkane or cycloalkene is a spirocyclic ring, one or more R1 groups may be substituted on the carbon atoms of the ring; the R1 group is selected from one of the following groups: alkyl, alkenyl, alkynyl, alkoxy, alkylthio, haloalkyl, cycloalkyl, cycloalkyloxy, cycloalkylthio, heterocyclic, heterocyclic oxy, heterocyclic thio, aryl, aryloxy, heteroaryl, heteroaryloxy, hydroxyl, mercapto, nitro, carboxyl, amino, ester, halogen, acyl, aldehyde.

[0071] In this invention, the cyclic ether compound containing one oxygen atom is selected from substituted or unsubstituted oxetanes, substituted or unsubstituted tetrahydrofurans, and substituted or unsubstituted tetrahydropyrans; the number of substituents may be one or more; the substituents are the R1 groups mentioned above.

[0072] In this invention, the cyclic ether compound containing one oxygen atom is selected from 3,3-dichloromethyloxetane, 2-chloromethyloxetane, 2-chloromethylepoxypropane, 1,3-epoxycyclohexane, 1,4-epoxycyclohexane, tetrahydrofuran, 2-methyltetrahydrofuran, 3-methyltetrahydrofuran, tetrahydropyran, 2-methyltetrahydropyran, oxetane, oxetane, oxetane, nonane, or oxetane.

[0073] In this invention, the cyclic ether compound containing two oxygen atoms is selected from substituted or unsubstituted 1,3-dioxolane (DOL) and substituted or unsubstituted 1,4-dioxane; the number of substituents may be one or more; the substituents are the R1 groups mentioned above.

[0074] In this invention, the cyclic ether compound containing three oxygen atoms is selected from substituted or unsubstituted paraformaldehyde; the number of substituents can be one or more; the substituents are the R1 groups mentioned above.

[0075] In this invention, the ether compound containing more oxygen is selected from substituted or unsubstituted 18-crown-6, substituted or unsubstituted 12-crown-4, and substituted or unsubstituted 24-crown-8; the number of substituents may be one or more; the substituents are the R1 groups mentioned above.

[0076] [Terms and Definitions]

[0077] Unless otherwise stated, the definitions of functional groups and terms described in this application, including definitions as examples, exemplary definitions, preferred definitions, definitions listed in tables, and definitions of specific compounds in the examples, can be arbitrarily combined and combined with each other. Such combinations and combinations of functional group definitions and compound structures shall fall within the scope of protection of this application.

[0078] The numerical range described in this application specification, when defined as "integer," should be understood as including the two endpoints of the range and every integer within the range. For example, "integers from 0 to 10" should be understood as including every integer of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. When the numerical range is defined as "number," it should be understood as including the two endpoints of the range, every integer within the range, and every decimal within the range. For example, "numbers from 0 to 10" should be understood as including not only every integer of 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10, but also at least the sum of each of these integers with 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and 0.9.

[0079] The term "halogen" as used in this invention refers to fluorine, chlorine, bromine, and iodine.

[0080] The term "alkyl" as used alone or as a suffix or prefix in this invention is intended to include branched and straight-chain saturated aliphatic hydrocarbon groups having 1 to 20, preferably 1 to 6, carbon atoms (or, if a specific number of carbon atoms is provided, that specific number). For example, "C 1-6 "Alkyl" means a straight-chain or branched alkyl group having 1, 2, 3, 4, 5, or 6 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl.

[0081] The use of "halogenated alkyl" or "alkyl halide" alone or as a suffix or prefix in this invention is intended to include branched and straight-chain saturated aliphatic hydrocarbon groups having at least one halogen substituent and having 1 to 20, preferably 1 to 6, carbon atoms (or, if a specific number of carbon atoms is provided, that specific number). For example, "C 1-10 "Halogenated alkyl" refers to an alkyl halogroup having 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms. Examples of alkyl halogroups include, but are not limited to, fluoromethyl, difluoromethyl, trifluoromethyl, chlorofluoromethyl, 1-fluoroethyl, 3-fluoropropyl, 2-chloropropyl, and 3,4-difluorobutyl.

[0082] The term "alkenyl" as used alone or as a suffix or prefix in this invention is intended to include branched and straight-chain aliphatic hydrocarbon groups comprising alkenyl or olefin having 2 to 20, preferably 2 to 6, carbon atoms (or, if a specific number of carbon atoms is provided, that specific number). For example, "C 2-6 "Alkenyl" refers to an alkenyl group having 2, 3, 4, 5, or 6 carbon atoms. Examples of alkenyl groups include, but are not limited to, vinyl, allyl, 1-propenyl, 1-butenyl, 2-butenyl, 3-butenyl, 2-methylbut-2-enyl, 3-methylbut-1-enyl, 1-pentenyl, 3-pentenyl, and 4-hexenyl.

[0083] The term "alkynyl" as used alone or as a suffix or prefix in this invention is intended to include branched and straight-chain aliphatic hydrocarbon groups comprising an alkynyl group or alkyne having 2 to 20, preferably 2 to 6, carbon atoms (or, if a specific number of carbon atoms is provided, that specific number). Examples include ethynyl, propynyl (e.g., 1-propynyl, 2-propynyl), 3-butynyl, pentyynyl, hexynyl, and 1-methylpentan-2-ynyl.

[0084] As used in this invention, the term "aryl" refers to an aromatic ring structure consisting of 5 to 20 carbon atoms. For example, an aromatic ring structure containing 5, 6, 7, and 8 carbon atoms can be a monocyclic aromatic group such as phenyl; a ring structure containing 8, 9, 10, 11, 12, 13, or 14 carbon atoms can be a polycyclic group such as naphthyl. The aromatic ring may be substituted with one or more of the aforementioned substituents at one or more ring positions. The term "aryl" also includes polycyclic systems having two or more rings, wherein two or more carbons are shared by two adjacent rings (the rings are "fused rings"), wherein at least one ring is aromatic and the other rings may be, for example, cycloalkyl, cycloalkenyl, cycloalkynyl, aryl, and / or heterocyclic groups. Examples of polycyclics include, but are not limited to, 2,3-dihydro-1,4-benzodioxanediene and 2,3-dihydro-1-benzofuran.

[0085] The term "cycloalkyl" as used in this invention is intended to include saturated cyclic groups having a specified number of carbon atoms. These terms may include fused or bridged polycyclic systems. Cycloalkyl groups have 3 to 40 carbon atoms in their ring structure. In one embodiment, a cycloalkyl group has 3, 4, 5, or 6 carbon atoms in its ring structure. For example, "C 3-6 "Cycloalkyl" refers to groups such as cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl.

[0086] As used in this invention, "heteroaryl" refers to a heterocyclic aromatic ring having at least one cyclic heteroatom (e.g., sulfur, oxygen, or nitrogen). Heteroaryl includes monocyclic and polycyclic systems (e.g., having 2, 3, or 4 fused rings). Examples of heteroaryl include, but are not limited to, pyridinyl, pyrazinyl, pyridazinyl, triazinyl, furanyl, quinolinyl, isoquinolinyl, thiopheneyl, imidazolyl, thiazolyl, indolyl, pyrroleyl, oxazolyl, benzofuranyl, benzothiopheneyl, benzothiazolyl, isoxazolyl, pyrazolyl, triazolyl, tetrazolyl, inzolyl, 1,2,4-thiadiazolyl, isothiazolyl, benzothiopheneyl, purinyl, carbazoleyl, benzoimidazolyl, benzoxazolyl, azabenzoxazolyl, imidazothiazolyl, benzo[1,4]dioxacyclohexenyl, benzo[1,3]dioxacyclopentenyl, etc. In some embodiments, the heteroaryl group has 3 to 40 carbon atoms, and in other embodiments, it has 3 to 20 carbon atoms. In some embodiments, the heteroaryl group comprises 3 to 14, 4 to 14, 3 to 7, or 5 to 6 cyclic atoms. In some embodiments, the heteroaryl group has 1 to 4, 1 to 3, or 1 to 2 heteroatoms. In some embodiments, the heteroaryl group has 1 heteroatom.

[0087] Unless otherwise stated, the term "heterocyclic group" as used in this invention refers to a saturated, unsaturated, or partially saturated monocyclic, bicyclic, or tricyclic ring comprising 3 to 20 atoms, wherein 1, 2, 3, 4, or 5 ring atoms are selected from nitrogen, sulfur, or oxygen, and unless otherwise stated, it may be linked by carbon or nitrogen, wherein the -CH2- group is optionally replaced by -C(O)-; and wherein, unless otherwise stated to the contrary, the cyclic nitrogen atom or cyclic sulfur atom is optionally oxidized to form an N-oxide or S-oxide, or the cyclic nitrogen atom is optionally quaternized; wherein the -NH in the ring is optionally replaced by an acetyl, formyl, methyl, or methanesulfonyl group; and the ring is optionally replaced by one or more halogens. It should be understood that when the total number of S and O atoms in the heterocyclic group exceeds 1, these heteroatoms are not adjacent to each other. If the heterocyclic group is bicyclic or tricyclic, at least one ring may optionally be a heteroaromatic ring or an aromatic ring, provided that at least one ring is non-heteroaromatic. If the heterocyclic group is monocyclic, it is necessarily not aromatic. Examples of heterocyclic groups include, but are not limited to, piperidinyl, N-acetylpiperidinyl, N-methylpiperidinyl, N-formylpiperazinyl, N-methanesulfonylpiperazinyl, homopiperazinyl, piperazinyl, azacyclic butyl, oxacyclic butyl, morpholinyl, tetrahydroisoquinolinyl, tetrahydroquinolinyl, dihydroindolyl, tetrahydropyranyl, dihydro-2H-pyranyl, tetrahydrofuranyl, tetrahydrothiaranyl, tetrahydrothiaran-1-oxide, tetrahydrothiaran-1,1-dioxide, 1H-pyridin-2-one, and 2,5-dioxoimidazolyl.

[0088] The preparation method of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0089] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0090] In the description of this invention, it should be noted that the terms "first," "second," etc., are used for descriptive purposes only and are not intended to indicate or imply relative importance.

[0091] Test method:

[0092] The conductivity described in this embodiment was obtained using an Interface 1000 electrochemical workstation from Gamry Corporation, with a test scan frequency of 1.0 Hz to 100 kHz.

[0093] In this embodiment, the lithium salt is pre-dehydrated by vacuum drying at 50°C for more than 24 hours before use.

[0094] In this embodiment, the cyclic ether compound is dehydrated by molecular sieve before use.

[0095] In this embodiment, the inorganic solid electrolyte is pre-dehydrated by vacuum drying at 60°C for more than 24 hours before use.

[0096] In this embodiment, the porous membrane is pre-treated by vacuum drying at 40°C for more than 12 hours before use to remove water.

[0097] In this embodiment, the decomposition voltage of the solid electrolyte membrane was tested using a lithium-stainless steel battery via linear sweep voltammetry. During the test, one side of the organic-inorganic composite solid electrolyte was in contact with the stainless steel sheet, and the other side was in contact with the lithium sheet.

[0098] In this embodiment, when the lithium-ion battery obtained using a solid electrolyte is subjected to a charge-discharge cycle test, the lithium-ion battery is subjected to a charge-discharge cycle test at 0.5C.

[0099] Preparation of positive electrode sheet for lithium-ion battery: 85 parts by mass of positive electrode active material nickel cobalt manganese (NCM532), 5 parts by mass of acetylene black, 5 parts by mass of conductive graphite, and 5 parts by mass of PVDF are thoroughly mixed with N-methylpyrrolidone (NMP) to obtain positive electrode slurry, which is uniformly coated on the surface of aluminum foil current collector and dried in a vacuum oven at 120℃ for later use.

[0100] Negative electrode: Lithium metal sheet.

[0101] Example 1

[0102] (1) Preparation of solid electrolyte membranes

[0103] Weigh 0.5g of LATP and 0.4g of lithium tetrafluoroborate into a reagent bottle, add 4.1g of tetrahydrofuran, and stir magnetically for 12h to ensure that the lithium salt, cyclic ether compound, and inorganic solid electrolyte are fully mixed and homogeneous, thus obtaining a polymerizable system (the specific composition and content are listed in Table 1). The polymerizable system is drop-coated onto one side of a polypropylene porous membrane, and polymerization is completed after standing at room temperature for 23h. The polymerized porous membrane is then dried in a vacuum oven for 12h to remove unpolymerized monomers, thus obtaining an asymmetric solid electrolyte membrane.

[0104] The prepared solid electrolyte membrane comprises a porous membrane, an organic-inorganic composite electrolyte layer on a first surface of the porous membrane, and a polymer electrolyte layer on a second surface of the porous membrane opposite to the first surface. The porous membrane contains a polymer electrolyte, which includes lithium salts and ether polymers. The organic-inorganic composite electrolyte in the organic-inorganic composite electrolyte layer includes lithium salts, ether polymers, and inorganic solid electrolytes. The polymer electrolyte in the polymer electrolyte layer includes lithium salts and ether polymers (specific compositions and contents are listed in Table 2).

[0105] (2) Battery manufacturing

[0106] The solid electrolyte membrane prepared above was used as an electrolyte in a lithium metal battery, and the cycle performance of the battery was tested using a Blue Battery charge-discharge tester (the test results are listed in Table 2). The lithium metal battery was prepared by placing one side of the solid electrolyte membrane containing the organic-inorganic composite solid electrolyte in contact with the positive electrode, and the other side in contact with the lithium metal negative electrode. After encapsulation and compaction, the membrane was assembled into a lithium metal battery.

[0107] Examples 2-9

[0108] (1) Preparation of asymmetric solid electrolyte membranes

[0109] The preparation method is the same as in Example 1, except that the composition and content of each component in the polymerizable system are different. The specific composition and content are listed in Table 1. In addition, the composition of the porous membrane is also different, and the composition and content of each component in the organic-inorganic composite electrolyte layer and polymer electrolyte layer on both sides of the obtained solid electrolyte membrane are different. The specific composition and content are listed in Table 2.

[0110] (2) Battery manufacturing

[0111] The preparation method is the same as in Example 1.

[0112] Comparative Example 1

[0113] (1) Preparation of homogeneous solid electrolyte membranes

[0114] 0.25 g of lithium fluorosulfonylimide and 0.25 g of lithium hexafluorophosphate were dissolved in 4.5 g of 1,4-epoxycyclohexane / 1,3-dioxolane (mass ratio 1:1) to obtain a mixed system. The mixed system was then dropped onto one side of a polypropylene porous membrane to allow the polypropylene porous membrane to be uniformly permeated by the mixed solution. After standing at room temperature for 12 h, the membrane was vacuum dried for 12 h to obtain a homogeneous solid electrolyte membrane.

[0115] The prepared solid electrolyte membrane includes a porous membrane, a polymer electrolyte layer on a first surface of the porous membrane, and a polymer electrolyte layer on a second surface of the porous membrane opposite to the first surface; the porous membrane contains a polymer electrolyte, which includes lithium salt and polymerized cyclic ether compounds; the polymer electrolyte in the polymer electrolyte layer includes lithium salt and polymerized cyclic ether compounds (the specific component contents are listed in Table 2).

[0116] (2) Battery manufacturing

[0117] The preparation method is the same as in Example 1.

[0118] Comparative Example 2

[0119] (1) Preparation of homogeneous solid electrolyte membranes

[0120] Weigh 1.46g LiBF4 into a reagent bottle, add 8.9g tetrahydrofuran, stir magnetically for 12h, and after mixing evenly, drop the solution onto a polyethylene porous membrane so that the polyethylene porous membrane is evenly permeated by the mixed solution. After standing at room temperature for 12h, vacuum dry for 12h to obtain a homogeneous solid electrolyte membrane.

[0121] The prepared solid electrolyte membrane includes a porous membrane, a polymer electrolyte layer on a first surface of the porous membrane, and a polymer electrolyte layer on a second surface of the porous membrane opposite to the first surface; the porous membrane contains a polymer electrolyte, which includes lithium salt and polymerized cyclic ether compounds; the polymer electrolyte in the polymer electrolyte layer includes lithium salt and polymerized cyclic ether compounds (the specific component contents are listed in Table 2).

[0122] (2) Battery manufacturing

[0123] The preparation method is the same as in Example 1.

[0124] Table 1. Composition of the polymerizable systems of Examples 1-9 and Comparative Examples 1-2

[0125]

[0126] Table 2. Composition of solid electrolyte membranes in Examples 1-9 and Comparative Examples 1-2

[0127]

[0128]

[0129] Table 3 Performance parameters of the batteries prepared in Examples 1-9 and Comparative Examples 1-2

[0130]

[0131] Figure 1 This is a charge-discharge diagram of the battery assembled using the asymmetric solid electrolyte membrane from Example 1 as the electrolyte for a lithium-ion battery. Figure 1 It can be seen that this asymmetric solid electrolyte membrane, as the electrolyte of a lithium-ion battery, enables the lithium-ion battery to charge and discharge normally and fully utilizes the active materials therein, resulting in a high specific capacity.

[0132] Figure 2 This is a cycle performance diagram of a battery assembled using the asymmetric solid electrolyte membrane from Example 2 as the electrolyte for a lithium-ion battery. Figure 2 It can be seen that this asymmetric solid electrolyte membrane, as an electrolyte for lithium-ion batteries, can exhibit stable cycle performance and its specific capacity remains basically unchanged.

[0133] Figure 3 This is a scanning electron microscope (SEM) image of the surface of the asymmetric solid electrolyte membrane (organic-inorganic electrolyte layer) in Example 1. Figure 3 It can be seen that the porous membrane surface is uniformly coated with an organic-inorganic electrolyte layer containing an inorganic solid electrolyte.

[0134] Figure 4 This is a scanning electron microscope (SEM) image of the surface of the asymmetric solid electrolyte membrane (polymer electrolyte layer) in Example 1. Figure 4 It can be seen that the porous membrane surface is uniformly coated with a polymer electrolyte layer, and the polymer does not contain inorganic solid electrolyte.

[0135] Figure 5 This is a cross-sectional scanning electron microscope (SEM) image of the asymmetric solid electrolyte membrane from Example 1. Figure 5 It can be seen that one side of the asymmetric solid electrolyte membrane is an organic-inorganic electrolyte layer containing inorganic solid electrolyte, and the other side is a polymer electrolyte layer containing polymer, and the interior of the porous membrane is completely wetted.

[0136] Figure 6 This is a surface scanning electron microscope (SEM) image of the LLZO inorganic solid electrolyte composite membrane coated on the surface of the PE membrane in Example 4. Figure 6 It can be seen that the surface of the porous membrane is uniformly coated with a layer of inorganic solid electrolyte.

[0137] Figure 7 This is a cross-sectional scanning electron microscope (SEM) image of the LLZO inorganic solid electrolyte composite membrane coated on the surface of the PE membrane in Example 4. Figure 7 It can be seen that one side of the porous membrane is coated with a uniform inorganic solid electrolyte, while the other side has no inorganic solid electrolyte.

[0138] Figure 8 This is a comparison graph showing the decomposition voltage of the solid electrolyte membranes in Example 4 and Comparative Example 1. Figure 8 It can be seen that the decomposition voltage of the asymmetric solid electrolyte membrane with added inorganic solid electrolyte (Example 4) can reach 4.5V, while the decomposition voltage of the ordinary liquid ether electrolyte membrane (Comparative Example 1) is only about 4.2V.

[0139] The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A solid-state electrolyte membrane, characterized by, The solid electrolyte membrane comprises a porous membrane and an organic-inorganic composite electrolyte layer on a first surface of the porous membrane, the porous membrane internally comprising a polymer electrolyte; the organic-inorganic composite electrolyte comprises a lithium salt, an ether polymer and an inorganic solid electrolyte; the polymer electrolyte comprises a lithium salt and an ether polymer; the ether polymer is obtained by ring-opening polymerization of a cyclic ether compound; In the organic-inorganic composite electrolyte, the mass percentage of the lithium salt is greater than or equal to 10 wt% and less than or equal to 40 wt%; the mass percentage of the ether polymer is greater than or equal to 40 wt% and less than or equal to 60 wt%; and the mass percentage of the inorganic solid electrolyte is greater than 10 wt% and less than or equal to 30 wt%. In the polymer electrolyte, the mass percentage of the lithium salt is greater than 5 wt% and less than or equal to 60 wt%; and the mass percentage of the ether polymer is greater than or equal to 15 wt% and less than or equal to 80 wt%.

2. The solid-state electrolyte film of claim 1, wherein, The solid electrolyte membrane has an asymmetric structure, and the solid electrolyte membrane with the asymmetric structure comprises a porous membrane, an organic-inorganic composite electrolyte layer on a first surface of the porous membrane, and a polymer electrolyte layer on a second surface of the porous membrane opposite to the first surface; the porous membrane internally comprises a polymer electrolyte; the organic-inorganic composite electrolyte comprises a lithium salt, an ether polymer and an inorganic solid electrolyte; the polymer electrolyte comprises a lithium salt and an ether polymer; and the ether polymer is obtained by ring-opening polymerization of a cyclic ether compound.

3. The solid-state electrolyte film of claim 1, wherein, The solid electrolyte membrane has a sandwich structure, and the solid electrolyte membrane with the sandwich structure comprises a porous membrane, organic-inorganic composite electrolyte layers on two side surfaces of the porous membrane, and a polymer electrolyte layer in the porous membrane; the polymer electrolyte comprises a lithium salt and an ether polymer; the ether polymer is obtained by ring-opening polymerization of a cyclic ether compound; and the organic-inorganic composite electrolyte comprises a lithium salt, an ether polymer and an inorganic solid electrolyte.

4. The solid-state electrolyte film of claim 2, wherein, The thickness of the polymer electrolyte layer on the second surface of the porous membrane opposite to the first surface is 0.01 μm to 2 μm, and the thickness of the organic-inorganic electrolyte layer on the first surface of the porous membrane is 0.1 μm to 5 μm.

5. The solid-state electrolyte film of claim 3, wherein, The thickness of the organic-inorganic electrolyte layers on the two surfaces of the porous membrane is 0.1 μm to 5 μm.

6. The solid-state electrolyte film according to any one of claims 1 to 5, wherein In the polymer electrolyte, the mass percentage of the lithium salt is greater than or equal to 10 wt% and less than or equal to 40 wt%; and the mass percentage of the ether polymer is greater than or equal to 40 wt% and less than or equal to 60 wt%.

7. The solid-state electrolyte film according to any one of claims 1 to 5, wherein The decomposition voltage of the solid electrolyte membrane is 4 V to 6 V. and / or the solid-state electrolyte film has an electrical conductivity of 1 x 10 -6 ~ 9 x 10 -1 S / cm; And / or, the thickness of the solid electrolyte membrane is 4 μm to 50 μm.

8. The method of producing a solid-state electrolyte film according to any one of claims 1 to 7, characterized by, The method comprises the following steps: (1) preparing a polymerizable system comprising a lithium salt, a cyclic ether compound and an inorganic solid electrolyte; (2) coating the polymerizable system of step (1) to a first surface of a porous membrane, standing, and allowing the cyclic ether compound in the polymerizable system to undergo a polymerization reaction to obtain the solid electrolyte membrane. Alternatively, (2') the polymerizable system of step (1) is coated on both surfaces of the porous membrane, and the cyclic ether compound in the polymerizable system is allowed to undergo polymerization reaction to obtain the solid electrolyte membrane.

9. The method of making of claim 8, wherein, In step (1), the mass percentage of the lithium salt in the polymerizable system is greater than 5wt% and less than or equal to 60wt%; the mass percentage of the cyclic ether compound is greater than or equal to 20wt% and less than or equal to 80wt%; and the mass percentage of the inorganic solid electrolyte is greater than 0wt% and less than or equal to 50wt%.

10. The method of making of claim 9, wherein, In the polymerizable system, the mass percentage of the lithium salt is greater than or equal to 10wt% and less than or equal to 40wt%; the mass percentage of the cyclic ether compound is greater than or equal to 40wt% and less than or equal to 60wt%; and the mass percentage of the inorganic solid electrolyte is greater than 0wt% and less than or equal to 30wt%.

11. The method of making of claim 8, wherein, In step (2) or (2'), the coating is selected from at least one of drop coating, blade coating, spin coating, spray coating, dip coating, and gravure coating.

12. The method of making of claim 8, wherein, In step (2) or (2'), the temperature for the standing is -40℃ to 60℃, and the time for the standing is 15 seconds to 300 hours.

13. The method of making of claim 8, wherein, In step (2), the method specifically comprises the following steps: In step (2'), the method specifically comprises the following steps:

14. The method of making of claim 8, wherein, In step (2'), the method specifically comprises the following steps: In step (2'), the method specifically comprises the following steps:

15. A secondary battery comprising the solid electrolyte membrane according to any one of claims 1-7.

16. The secondary battery according to claim 15, wherein The secondary battery is at least one of a button cell, a stacked cell, and a wound cell.

17. The secondary battery according to claim 15, wherein The outer package of the secondary battery is a soft plastic package or a steel shell package.

18. The secondary battery of claim 15, wherein, The secondary battery is at least one of a lithium ion battery, a lithium-sulfur battery, a lithium-air battery, and a sodium ion battery.

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