Composite electrolyte membrane, preparation method therefor, and use thereof

Abstract

A composite electrolyte membrane, a preparation method therefor, and a use thereof. The composite electrolyte membrane contains an oxide electrolyte, polyethylene oxide, polyether-based polyurethane, a lithium salt, and a plasticizer, wherein the oxide electrolyte accounts for 50% or more of the total weight of the composite electrolyte membrane. The composite electrolyte membrane has high ionic conductivity and also has high mechanical strength, flexibility, and ductility.

Description

Composite electrolyte membrane and its preparation method and application Technical Field

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

[0002] Lithium-ion battery separator materials typically include inorganic solid electrolytes (such as ceramics and glass), polymer electrolytes, and polymer-ceramic composite electrolytes. Composite electrolyte membranes are typically prepared using a wet process. The wet process can include the following steps: 1) dissolving a polymer electrolyte in an organic solvent to produce a polymer solution; 2) adding ceramic electrolyte powder to the polymer solution and stirring thoroughly to produce an electrolyte slurry; and 3) casting the resulting electrolyte slurry onto a substrate and drying it to produce the composite electrolyte membrane.

[0003] However, existing composite electrolyte membranes usually require a wet preparation method involving solvents, and it is difficult to simultaneously obtain a higher electrolyte content and good mechanical properties.

[0004] Summary of the Invention

[0005] In response to the above technical problems, the present invention provides a composite electrolyte membrane, which comprises an oxide electrolyte, polyethylene oxide, polyether polyurethane, a lithium salt and a plasticizer; wherein the oxide electrolyte accounts for more than 50% relative to the total weight of the composite electrolyte membrane.

[0006] In some specific embodiments, relative to the total weight of the composite electrolyte membrane, the oxide electrolyte accounts for 60-90%, the polyethylene oxide accounts for 1-10%, the polyether polyurethane accounts for 1-10%, the lithium salt accounts for 1-15%, and the plasticizer accounts for 1-15%.

[0007] In some specific embodiments, the oxide electrolyte is one or more of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum titanate oxide (LLTO), and lithium aluminum germanium phosphate (LAGP).

[0008] In some specific embodiments, the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2), lithium bis(oxalatoborate) (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium difluorooxalatoborate (LiDFOB).

[0009] In some specific embodiments, the plasticizer is one or more of succinonitrile, polyethylene glycol, and dioctyl phthalate.

[0010] In some specific embodiments, the weight ratio of the polyethylene oxide to the polyether polyurethane is 1:0.5-2, preferably 1:0.8-1.2.

[0011] In some specific embodiments, the composite electrolyte membrane is prepared by a dry process.

[0012] A second aspect of the present invention provides a method for preparing a solid electrolyte membrane, the method comprising the following steps:

[0013] (1) mixing an oxide electrolyte with polyethylene oxide, polyether polyurethane, a lithium salt, and a plasticizer to obtain a material mixture;

[0014] (2) forming the material mixture to obtain a solid electrolyte membrane;

[0015] Wherein, relative to the total weight of the material mixture, the oxide electrolyte accounts for more than 50%.

[0016] In some specific embodiments, relative to the total weight of the material mixture, the oxide electrolyte accounts for 60-90%, the polyethylene oxide accounts for 1-10%, the polyether polyurethane accounts for 1-10%, the lithium salt accounts for 1-15%, and the plasticizer accounts for 1-15%.

[0017] In some embodiments, the feed mixture does not contain a solvent.

[0018] In some specific embodiments, the oxide electrolyte is one or more of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum titanate oxide (LLTO), and lithium aluminum germanium phosphate (LAGP).

[0019] In some specific embodiments, the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2), lithium bis(oxalatoborate) (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium difluorooxalatoborate (LiDFOB).

[0020] In some specific embodiments, the plasticizer is one or more of succinonitrile, polyethylene glycol, and dioctyl phthalate.

[0021] In some specific embodiments, the weight ratio of the polyethylene oxide to the polyether polyurethane is 1:0.5-2, preferably 1:0.8-1.2.

[0022] In some specific embodiments, in step (1), the mixing is performed by grinding, and preferably the grinding time is more than 10 minutes.

[0023] In some specific embodiments, in step (2), the molding is performed by pressure molding, and the molding temperature is preferably 60-80°C.

[0024] In some specific embodiments, in step (2), before the molding, the material mixture is subjected to one or more of the following treatments: fiberization, melting, and softening.

[0025] The third aspect of the present invention provides use of the composite electrolyte membrane of the first aspect of the present invention or the composite electrolyte membrane prepared by the preparation method of the second aspect of the present invention in a lithium ion battery.

[0026] Advantageous Effects of the Invention

[0027] The present invention creatively combines polyethylene oxide and polyether polyurethane for the preparation of a composite electrolyte membrane, thereby achieving a high content of oxide electrolyte addition. The composite electrolyte membrane thus prepared has very high ionic conductivity while also having high mechanical strength, flexibility and ductility.

[0028] In the composite electrolyte membrane of the present invention, by mixing polyether polyurethane and polyethylene oxide, a mixed ion transport path can be provided to promote Li + The shift from single-chain transport to three-dimensional network transport significantly improves the electrolyte membrane's ionic conductivity. Furthermore, the spring-like properties of the soft and hard segments in the polyether polyurethane molecular chain significantly enhance the membrane's mechanical strength and flexibility. Polyethylene oxide possesses strong adhesive strength, while polyether polyurethane offers both rigidity and flexibility, compensating for the inherent strength and toughness limitations of polyethylene oxide. This allows for the simultaneous application of these excellent properties in the composite electrolyte membrane.

[0029] Furthermore, the composite electrolyte membrane of the present invention is preferably prepared by a dry membrane preparation process, which does not use solvents during the preparation process, has a simple process, high efficiency, and can be produced continuously. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 shows a schematic structural diagram of a composite electrolyte membrane of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described below through specific embodiments. Unless otherwise specified, the technical terms used herein have the same meanings as those generally understood by those skilled in the art.

[0032] The numerical limits or ranges stated herein are inclusive and specifically include all values ​​and subranges within the numerical limits or ranges. In the present invention, "%" means "% by weight" unless otherwise stated.

[0033] As used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0034] A first aspect of the present invention provides a composite electrolyte membrane, which comprises an oxide electrolyte, polyethylene oxide, polyether polyurethane, a lithium salt and a plasticizer; wherein the oxide electrolyte accounts for more than 50% of the total weight of the composite electrolyte membrane.

[0035] The structural schematic diagram of the composite electrolyte membrane of the present invention is shown in Figure 1, where the gray large and small balls represent oxide electrolyte particles; the combination of thin solid curved line segments and thick straight line segments represents polyether polyurethane molecular chains, wherein the thick straight line segments are hard segments and the thin curved line segments are soft segments; and the dotted curved line segments represent polyethylene oxide molecular chains.

[0036] In the present invention, the oxide electrolyte can be any oxide electrolyte commonly used in lithium ion batteries, such as a ceramic oxide electrolyte. As the oxide electrolyte, for example, it can be selected from lithium lanthanum zirconium oxide (LLZO, i.e., Li7La3Zr2O 12 ), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum titanate (LLTO), lithium aluminum germanium phosphate (LAGP). Furthermore, the oxide electrolyte may also contain one or more doping elements selected from aluminum, gallium, and tantalum. According to some specific embodiments of the present invention, the oxide electrolyte may be aluminum-doped lithium lanthanum zirconium oxide (LALZO, such as Li (7-x) Al (x) La3Zr (2-x) O 12 , where x can be 0.01-0.8).

[0037] The oxide electrolyte is preferably added in the form of powder, and the number average particle size of the oxide electrolyte is preferably 0.5-5 μm, preferably 0.8-2 μm.

[0038] According to a preferred embodiment of the present invention, the ionic conductivity of the composite electrolyte membrane is 2*10 -4 S / cm or more, preferably 3*10 -4 S / cm or more.

[0039] According to a preferred embodiment of the present invention, the oxide electrolyte accounts for 60-90%, preferably 80-90%, of the total weight of the composite electrolyte membrane. In addition, the oxide electrolyte may account for, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% of the total weight of the composite electrolyte membrane.

[0040] In the present invention, the polyethylene oxide used preferably has a number average molecular weight of 500,000 to 1,000,000, preferably 500,000 to 800,000, for example 600,000. According to a preferred embodiment of the present invention, the polyethylene oxide accounts for 1-10%, preferably 2-5%, relative to the total weight of the composite electrolyte membrane. Furthermore, the polyethylene oxide may account for, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% of the total weight of the composite electrolyte membrane.

[0041] In the present invention, the -COC- in the polyether structure of the polyether polyurethane has a complex Li + The ability of PEO polymer electrolyte to conduct Li + , precisely because of the presence of -COC- functional groups in its long chain. Polyether polyurethane elastomers are composed of hard segments formed by the reaction of diisocyanate with small molecule diols and soft segments formed by the reaction with long chain polyether polyols. The -COC- functional groups in the soft segments participate in the Li + The hard segments act as physical crosslinking points to enhance the mechanical strength of the polymer. Thanks to the spring-like properties of the molecular chain, polyether polyurethane has high mechanical strength and high elasticity. According to a preferred embodiment of the present invention, the polyether polyurethane accounts for 1-10% of the total weight of the composite electrolyte membrane, preferably 2-5%. In addition, the polyether polyurethane may account for, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10% of the total weight of the composite electrolyte membrane.

[0042] In the present invention, the lithium salt can use any lithium salt commonly used in lithium-ion batteries, for example, it can be selected from one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2), lithium bis(oxalatoborate) (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium difluorooxalatoborate (LiDFOB), wherein lithium bis(trifluoromethanesulfonyl)imide is preferred. According to a preferred embodiment of the present invention, the lithium salt accounts for 1-15% of the total weight of the composite electrolyte membrane, preferably 5-8%. In addition, the lithium salt may account for, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15% of the total weight of the composite electrolyte membrane.

[0043] In the present invention, the plasticizer can use any plasticizer commonly used in lithium-ion batteries, for example, it can be one or more of succinonitrile (SN), polyethylene glycol, and dioctyl phthalate, wherein succinonitrile is preferred. According to a preferred embodiment of the present invention, the plasticizer accounts for 1-15% of the total weight of the composite electrolyte membrane, preferably 6-10%. In addition, the plasticizer accounts for, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15% of the total weight of the composite electrolyte membrane.

[0044] According to some preferred embodiments of the present invention, the weight ratio of polyethylene oxide to polyether polyurethane is 1:0.5-2, preferably 1:0.8-1.2. By adopting the above-mentioned weight ratio of polyethylene oxide to polyether polyurethane, a composite electrolyte membrane with better ionic conductivity, tensile strength, and elongation can be obtained. In addition, the weight ratio of polyethylene oxide to polyether polyurethane in the total weight of the composite electrolyte membrane can be, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, or 1:2, etc.

[0045] According to the present invention, the ionic conductivity of the composite electrolyte membrane can reach 2*10 -4 S / cm or more, preferably 3*10 -4 S / cm or more, 4*10 -4 S / cm or above or 5*10 -4 S / cm or more. Specifically, the ionic conductivity of the composite electrolyte membrane can be, for example, 2*10-4 Up to 6*10 -4 S / cm.

[0046] According to the present invention, the tensile strength of the composite electrolyte membrane may be greater than 2 MPa, for example, 2-7 MPa; in addition, the elongation may be greater than 5%, for example, 5-25%.

[0047] According to the present invention, in order to further improve the performance of the composite electrolyte membrane, the composite electrolyte membrane is preferably prepared by a dry process, that is, no solvent is used in the preparation of the composite electrolyte membrane.

[0048] A second aspect of the present invention provides a method for preparing a solid electrolyte membrane, the method comprising the following steps:

[0049] (1) mixing an oxide electrolyte with polyethylene oxide, polyether polyurethane, a lithium salt, and a plasticizer to obtain a material mixture;

[0050] (2) forming the material mixture to obtain a solid electrolyte membrane;

[0051] Wherein, relative to the total weight of the material mixture, the oxide electrolyte accounts for more than 50%.

[0052] In the present invention, the oxide electrolyte can use any oxide electrolyte commonly used in lithium-ion batteries, such as a ceramic oxide electrolyte. As the oxide electrolyte, it can be one or more selected from lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum titanate oxide (LLTO), and lithium aluminum germanium phosphate (LAGP). Furthermore, the oxide electrolyte can also contain one or more doping elements selected from aluminum, gallium, and tantalum. According to some specific embodiments of the present invention, the oxide electrolyte can be aluminum-doped lithium lanthanum zirconium oxide (LALZO). According to a preferred embodiment of the present invention, the oxide electrolyte accounts for 60-90% relative to the total weight of the material mixture, preferably 80-90%. In addition, the oxide electrolyte accounts for, for example, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85% or 90% of the total weight of the material mixture.

[0053] In the present invention, the polyethylene oxide used preferably has a number average molecular weight of 500,000 to 1,000,000, more preferably 500,000 to 800,000, for example 600,000. According to a preferred embodiment of the present invention, the polyethylene oxide accounts for 1-10%, preferably 2-5%, relative to the total weight of the material mixture. Furthermore, the polyethylene oxide may account for, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% of the total weight of the material mixture.

[0054] In the present invention, the -COC- in the polyether structure of the polyether polyurethane has a complex Li + The ability of PEO polymer electrolyte to conduct Li + , precisely because of the presence of -COC- functional groups in its long chain. Polyether polyurethane elastomers are composed of hard segments formed by the reaction of diisocyanate with small molecule diols and soft segments formed by the reaction with long chain polyether polyols. The -COC- functional groups in the soft segments participate in the Li + The hard segments act as physical crosslinking points to enhance the mechanical strength of the polymer. Thanks to the spring-like properties of the molecular chain, polyether polyurethane has high mechanical strength and high elasticity. According to a preferred embodiment of the present invention, the proportion of polyether polyurethane is 1-10%, preferably 2-5%, relative to the total weight of the composite electrolyte membrane. In addition, the proportion of polyether polyurethane in the total weight of the material mixture can be, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0055] In the present invention, the lithium salt can use any lithium salt commonly used in lithium-ion batteries, for example, it can be selected from one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2), lithium bis(oxalatoborate) (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium difluorooxalatoborate (LiDFOB), wherein lithium bis(trifluoromethanesulfonyl)imide is preferred. According to a preferred embodiment of the present invention, the lithium salt accounts for 1-15% of the total weight of the material mixture, preferably 5-8%. In addition, the lithium salt may account for 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15% of the total weight of the material mixture, for example.

[0056] In the present invention, the plasticizer can use any plasticizer commonly used in lithium ion batteries, for example, it can be one or more of succinonitrile (SN), polyethylene glycol, dioctyl phthalate, wherein succinonitrile is preferred. According to a preferred embodiment of the present invention, the plasticizer accounts for 1-15% relative to the total weight of the material mixture, preferably 6-10%. In addition, in the total weight of the material mixture, the plasticizer accounts for, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14% or 15%, etc.

[0057] According to some preferred embodiments of the present invention, the weight ratio of polyethylene oxide to polyether polyurethane is 1:0.5-2, preferably 1:0.8-1.2. By adopting the above-mentioned weight ratio of polyethylene oxide to polyether polyurethane, a composite electrolyte membrane with better ionic conductivity, tensile strength, and elongation can be obtained. In addition, the weight ratio of polyethylene oxide to polyether polyurethane in the total weight of the composite electrolyte membrane can be, for example, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, or 1:2, etc.

[0058] In step (1), the mixing is performed so that the material mixture is uniformly mixed, and any mixing method known in the art can be used. In order to fully mix the above materials, in step (1), the mixing is performed by grinding, preferably for a grinding time of more than 10 minutes, for example, 10-30 minutes.

[0059] According to a preferred embodiment of the present invention, the material mixture does not contain a solvent. The solvent includes, but is not limited to, acetonitrile (ACN), N-methylpyrrolidone (NMP), dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), tetrahydrofuran (THF), etc. In other words, the solid electrolyte membrane of the present invention is prepared by a dry process.

[0060] In step (2), the uniformly mixed material mixture is prepared to form a composite electrolyte membrane. For example, the molding can be performed by press molding. Preferably, the molding temperature is 40-90°C, more preferably 60-80°C. The press molding can be performed by flat plate pressing or roller pressing, using any instrument commonly used in the art for pressing composite electrolyte membranes.

[0061] According to a preferred embodiment of the present invention, in step (2), before the molding, the material mixture is subjected to one or more of the following treatments: fiberization, melting, and softening. Fiberization may include applying a certain shear force to the material mixture to fiberize it; melting may include heating the material mixture to a temperature above the melting point of the polymer to melt it; and softening may include heating the material mixture to a temperature slightly below the melting point of the polymer to soften it.

[0062] The third aspect of the present invention provides use of the composite electrolyte membrane of the first aspect or the composite electrolyte membrane prepared by the preparation method of the second aspect in a lithium ion battery.

[0063] Example

[0064] The experimental methods in the following examples are conventional methods unless otherwise specified.

[0065] In the following examples and comparative examples, the relevant reagents used are shown in Table 1 below.

[0066] Table 1

[0067] In the following examples and comparative examples, the main instruments used are as follows:

[0068] High-speed grinder: Liren Grinding Mill, Liren Electric, MFJ-W317.

[0069] Roller press: Laboratory heated electrode roller press, Xiamen Tianmeifu Machinery Equipment Co., Ltd., TMAX-JRDG100.

[0070] Example 1

[0071] 8g of 500nm LLZO powder, 0.2g of PEO, 0.4g of polyether polyurethane, 0.6g of LiTFSI, and 0.8g of SN were weighed and ground for 30 minutes. The ground electrolyte mixture was repeatedly rolled on a roller press at 80°C to form a composite electrolyte membrane with a thickness of 30μm.

[0072] Example 2

[0073] A composite electrolyte membrane was prepared according to the method of Example 1, except that the added amount of PEO was changed to 0.3 g and the added amount of polyether polyurethane was changed to 0.3 g.

[0074] Example 3

[0075] A composite electrolyte membrane was prepared according to the method of Example 1, except that the added amount of PEO was changed to 0.4 g and the added amount of polyether polyurethane was changed to 0.2 g.

[0076] Example 4

[0077] A composite electrolyte membrane was prepared according to the method in Example 1, except that the amount of LLZO powder added was changed to 6 g.

[0078] Example 5

[0079] A composite electrolyte membrane was prepared according to the method in Example 1, except that the amount of LLZO powder added was changed to 9 g.

[0080] Comparative Example 1

[0081] A composite electrolyte membrane was prepared according to the method of Example 1, except that the amount of PEO added was changed to 0.6 g and polyether polyurethane was not added.

[0082] Comparative Example 2

[0083] A composite electrolyte membrane was prepared according to the method of Example 1, except that the amount of polyether polyurethane added was changed to 0.6 g and PEO was not added.

[0084] Comparative Example 3

[0085] The composite electrolyte membrane was prepared using a wet process. Specifically, 0.3g of PEO and 0.3g of polyether polyurethane were added to ACN solvent and stirred to fully dissolve. To this mixed solution were added 8g of 500nm LLZO powder, 0.6g of LiTFSI, and 0.8g of SN. The mixture was stirred and ultrasonicated to uniformly disperse the slurry. The slurry was cast onto a PET film and thoroughly dried at 60°C. A composite electrolyte membrane with a thickness of 30μm was obtained.

[0086] Test Case

[0087] The composite electrolyte membranes obtained in the above examples and comparative examples were subjected to performance tests according to the following methods.

[0088] Test method:

[0089] Ionic conductivity: Stainless steel sheets were placed on both sides of the solid electrolyte membrane as blocking electrodes, and a button cell was assembled. AC impedance testing was performed using an electrochemical workstation. Appropriate amplitude voltage and frequency were set, and the test results were fitted to calculate the ionic conductivity.

[0090] The formula for calculating ionic conductivity is: σ = d / (R × S), where σ represents conductivity; R is the impedance value of the electrolyte membrane obtained by testing, in Ω; S is the electrode area, in cm 2 ; d is the thickness of the electrolyte membrane, in cm.

[0091] Tensile strength refers to the ratio of the maximum tensile force a sample can withstand to its cross-section during a tensile test. Tensile strength and elongation are measured in accordance with the requirements of GB / T1040.3 2006, the test method for plastic films.

[0092] The measured results are shown in Table 2.

[0093] Table 2

[0094] The results in Table 1 demonstrate that, compared to Comparative Examples 1-3, the examples of the present invention all provide composite electrolyte membranes that exhibit both high ionic conductivity and high mechanical strength, flexibility, and ductility. Furthermore, when the PEO content is 80% and the weight ratio of PEO to polyether polyurethane is 1:1, the resulting composite electrolyte membrane exhibits the highest ionic conductivity and tensile strength.

Claims

1. A composite electrolyte membrane, characterized in that: The composite electrolyte membrane comprises an oxide electrolyte, polyethylene oxide, polyether polyurethane, a lithium salt and a plasticizer; Wherein, relative to the total weight of the composite electrolyte membrane, the oxide electrolyte accounts for more than 50%.

2. The composite electrolyte membrane according to claim 1, wherein: Relative to the total weight of the composite electrolyte membrane, the oxide electrolyte accounts for 50-90%, the polyethylene oxide accounts for 1-10%, the polyether polyurethane accounts for 1-10%, the lithium salt accounts for 1-15%, and the plasticizer accounts for 1-15%; Preferably, the ionic conductivity of the composite electrolyte membrane is 2*10 -4 S / cm or more, preferably 3*10 -4 S / cm or more.

3. The composite electrolyte membrane according to claim 1 or 2, wherein: The oxide electrolyte is one or more of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum titanium oxide (LLTO), and lithium aluminum germanium phosphate (LAGP); Preferably, the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2), lithium bis(oxalatoborate) (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium difluorooxalatoborate (LiDFOB); Preferably, the plasticizer is one of succinonitrile, polyethylene glycol, dioctyl phthalate, kind or multiple.

4. The composite electrolyte membrane according to any one of claims 1 to 3, wherein: The weight ratio of the polyethylene oxide to the polyether polyurethane is 1:0.5-2, preferably 1:0.8-1.

2.

5. The composite electrolyte membrane according to any one of claims 1 to 4, wherein: The composite electrolyte membrane is prepared by a dry method.

6. A method for preparing a solid electrolyte membrane, characterized in that: The preparation method comprises the following steps: (1) mixing an oxide electrolyte with polyethylene oxide, polyether polyurethane, a lithium salt and a plasticizer to obtain a material mixture; (2) forming the material mixture to obtain a solid electrolyte membrane; Wherein, relative to the total weight of the material mixture, the oxide electrolyte accounts for more than 50%.

7. The preparation method according to claim 6, wherein: Relative to the total weight of the material mixture, the oxide electrolyte accounts for 50-90%, the polyethylene oxide accounts for 1-10%, the polyether polyurethane accounts for 1-10%, the lithium salt accounts for 1-15%, and the plasticizer accounts for 1-15%; Preferably, the material mixture does not contain a solvent.

8. The preparation method according to claim 6 or 7, wherein: The oxide electrolyte is one or more of lithium lanthanum zirconium oxide (LLZO), lithium lanthanum zirconium tantalum oxide (LLZTO), lithium lanthanum titanium oxide (LLTO), and lithium aluminum germanium phosphate (LAGP); Preferably, the lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium perchlorate (LiClO4), lithium hexafluoroarsenate (LiAsF6), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethylsulfonyl)imide (LiN(CF3SO2)2), lithium bis(oxalatoborate) (LiBOB), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium difluorooxalatoborate (LiDFOB); Preferably, the plasticizer is one or more of succinonitrile, polyethylene glycol, and dioctyl phthalate; Preferably, the weight ratio of the polyethylene oxide to the polyether polyurethane is 1:0.5-2, preferably 1:0.8-1.

2.

9. The preparation method according to any one of claims 6 to 8, wherein In step (1), the mixing is performed by grinding, and preferably the grinding time is more than 10 minutes; Preferably, in step (2), the molding is performed by pressure molding, and the molding temperature is preferably 60-80°C; Preferably, in step (2), before the molding, the material mixture is subjected to one or more of the following treatments: fiberization, melting, and softening.

10. Use of the composite electrolyte membrane according to any one of claims 1 to 5 or the composite electrolyte membrane prepared by the preparation method according to any one of claims 6 to 9 in a lithium ion battery.

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