Solid electrolyte membrane, method for manufacturing the same, secondary battery, and electric device

Abstract

The application provides a solid electrolyte membrane and a preparation method thereof, a secondary battery and an electric device. The solid electrolyte membrane of the application comprises the following components: polyvinylidene fluoride or a copolymer thereof, polyimide or a copolymer thereof, an electrolyte salt, and an aminopolycarboxylate. The solid electrolyte membrane is prepared by taking polyvinylidene fluoride or a copolymer thereof as a matrix, and adding polyimide and an aminopolycarboxylate to improve the crystallization performance of polyvinylidene fluoride, so that a dense, high Young's modulus, flame-retardant composite polymer electrolyte membrane is obtained. The solid electrolyte membrane prepared by the application has a Young's modulus of ≥ 9.5 GPa at a thickness of 10 μm, an ionic conductivity of > 4*10 ‑4 S / cm at 25 ℃, and a capacity retention rate after 600 cycles at 1 C, all of which are above 85%.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of batteries, in particular to a solid-state electrolyte film, a preparation method thereof, a secondary battery and an electric device. BACKGROUND

[0002] At present, polymer electrolytes show greater processing versatility and better electrode compatibility than inorganic ceramic electrolytes. Unfortunately, due to the relatively poor inhibition effect of the mechanical strength of the polymer electrolyte on lithium dendrites, a greater thickness is still needed to ensure the long-term operation of the lithium metal battery, thereby reducing the energy density of the battery. In addition, the low ionic conductivity and unsatisfactory thermal stability of the polymer electrolyte also hinder its practical application in high-energy, high-safety lithium metal batteries.

[0003] In view of this, the present application is proposed. SUMMARY

[0004] The purpose of the present application is to overcome the above-mentioned problems in the prior art, to provide a polymer solid-state electrolyte film, which has high ionic conductivity, easy cutting processing, high mechanical strength, good electrochemical and thermal stability, etc., so as to realize the preparation and application of ultra-thin lithium metal electrolyte with high energy density, long cycle life and good safety.

[0005] To achieve the above-mentioned purpose, the first aspect of the present application provides a solid-state electrolyte film, which comprises the following components:

[0006] A polymer matrix, an electrolyte salt, and an amino polycarboxylate; the polymer matrix comprises polyvinylidene fluoride or a copolymer thereof, polyimide or a copolymer thereof.

[0007] As an embodiment of the present application, the solid-state electrolyte film comprises the following components by weight:

[0008] 100 parts of the polymer matrix, 15-20 parts of the electrolyte salt, 0.1-5 parts of the film-forming agent, and 1-5 parts of the amino polycarboxylate.

[0009] As an embodiment of the present application, the polymer matrix satisfies: 30%≤M2 / (M1+M2)≤45%, M1 represents the weight parts of polyvinylidene fluoride or a copolymer thereof; M2 represents the weight parts of polyimide or a copolymer thereof.

[0010] As an embodiment of the present application, the polyvinylidene fluoride or a copolymer thereof comprises at least one of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (P(VDF-HFP)) copolymer, and polyvinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene (P(VDF-TrFE-CTFE)) terpolymer.

[0011] As an embodiment of the present application, the polyimide or the copolymer thereof includes at least one of polyimide (PI), polyimide-siloxane block copolymer, and polylactic acid-polyimide block copolymer (PLA-PI-PLA).

[0012] As an embodiment of the present application, the melt viscosity of the polyvinylidene fluoride or the copolymer thereof is denoted as η A , and the melt viscosity of the polyimide or the copolymer thereof is denoted as η B , and satisfies: η B - η A ≥ 500 cps.

[0013] As an embodiment of the present application, it satisfies: 1.0 ≤ η B / η A ≤ 1.5.

[0014] As an embodiment of the present application, η A = 3000-4000 cps.

[0015] As an embodiment of the present application, η B = 3500-5000 cps.

[0016] As an embodiment of the present application, the electrolyte salt includes at least one of sodium bis(trifluoromethylsulfonyl)imide (NaTFSI) and sodium hexafluorophosphate (NaPF6).

[0017] As an embodiment of the present application, the number of carboxyl groups in the aminopolycarboxylate is 5-6.

[0018] In a second aspect of the present application, a preparation method of the solid-state electrolyte film according to the first aspect of the present application is provided, including the following steps:

[0019] According to the weight parts, polyvinylidene fluoride or the copolymer thereof, polyimide or the copolymer thereof, and electrolyte salt are dissolved in an organic solvent to be uniformly mixed, and then an aminopolycarboxylate is added to obtain a mixed solution by dissolution, a precursor film is obtained by using a casting method, and the solid-state electrolyte film can be obtained by drying.

[0020] As an embodiment of the present application, the organic solvent includes at least one of trimethyl phosphate (TMP), triethyl phosphate (TEP), triphenyl phosphate (TPP), and N,N-dimethylformamide (DMF).

[0021] As an embodiment of the present application, the temperature for the dissolution is 60-160°C.

[0022] As an embodiment of the present application, the temperature for the drying is 80-100°C.

[0023] In a third aspect, the application provides a secondary battery, comprising a positive electrode sheet, the solid-state electrolyte film according to the first aspect of the application, and a negative electrode sheet.

[0024] In a fourth aspect, the application provides an electrical equipment, comprising the secondary battery according to the third aspect of the application.

[0025] Compared with the prior art, the application has the following beneficial effects:

[0026] In the application, polyvinylidene fluoride or its copolymer, polyimide or its copolymer are used as the polymer matrix to prepare the solid-state electrolyte film, and amino polycarboxylate is added to improve the crystallization performance of the polymer matrix, so that a dense, high Young's modulus flame-retardant composite polymer electrolyte film is obtained. In the application, the solid-state electrolyte film prepared has a Young's modulus of ≥ 9.5 GPa at a thickness of 10 μm, an ionic conductivity of > 4*10 -4 S / cm at 25℃, and a capacity retention rate of > 85% after 600 cycles at 1C. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the embodiments of the application clearer, the technical solutions in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the application.

[0028] In the application, the open technical features include the closed technical solutions composed of the listed features, and also include the open technical solutions containing the listed features.

[0029] In the application, if no special description is given, the numerical range is regarded as continuous and includes the minimum value and the maximum value of the range and each value between the minimum value and the maximum value. Further, when the range refers to an integer, each integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or a characteristic, the ranges can be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all sub-ranges included therein.

[0030] The reagents or instruments used in the application are not marked with the manufacturer, and are conventional products that can be obtained from the market.

[0031] In a first aspect, the application provides a solid-state electrolyte film, comprising the following components:

[0032] polymer matrix, electrolyte salt, aminopolycarboxylate; the polymer matrix comprises polyvinylidene fluoride (PVDF) or a copolymer thereof, polyimide (PI) or a copolymer thereof.

[0033] The application uses polyvinylidene fluoride or a copolymer thereof, polyimide or a copolymer thereof as the polymer matrix to prepare a solid-state electrolyte film, and adds aminopolycarboxylate to improve the crystallization performance of the polymer matrix, so as to obtain a dense, high Young's modulus, and flame-retardant composite polymer electrolyte film.

[0034] The active conjugated carbonyl group in the PI polymer skeleton is conducive to ion conduction, because the negatively charged N and O atoms accelerate the dissociation of sodium salt through electrostatic interaction, so that the ionic conductivity and ion transfer number of the electrolyte are greatly improved. In addition, the polyimide with high flame retardancy has a certain affinity for polyvinylidene fluoride, thereby enhancing the mechanical strength of the electrolyte film and reducing the thermal shrinkage rate; the conventional PVDF structure is TGTG' type, and the fluorine atoms are arranged on both sides of the carbon chain, and the large steric hindrance and long transmission path seriously affect the lithium ion transmission efficiency, and the strong electron-donating property of the amino group in the aminopolycarboxylate induces the conformation of PVDF to change from TGTG' to TTTT', and the PVDF with TTTT' structure can ensure that all fluorine atoms are arranged on the same side, shortens the transmission path of ions, promotes the dissociation of ions of the electrolyte, and fixes the anions of the electrolyte salt, thereby improving the ionic conductivity of the electrolyte; in addition, the strong electron-donating effect of the aminopolycarboxylate also increases the electron density around the polymer molecules, so that there are more nucleation sites in the polymer, which reduces the diameter of the polymer ball and increases the continuity of the polymer film.

[0035] In some embodiments of the application, the solid-state electrolyte film comprises the following components by weight:

[0036] 100 parts of polymer matrix, 15-20 parts of electrolyte salt, 0.1-5 parts of film-forming agent, and 1-5 parts of aminopolycarboxylate.

[0037] In some embodiments of the application, the polymer matrix satisfies: 30%≤M2 / (M1+M2)≤45%, M1 represents the weight parts of polyvinylidene fluoride or a copolymer thereof; and M2 represents the weight parts of polyimide or a copolymer thereof.

[0038] When a higher content of PI is introduced into the polyvinylidene fluoride-based polymer, although the mechanical strength and non-combustibility of the composite electrolyte are greatly improved, a large amount of PI tends to form a porous structure during film formation, thereby deteriorating the electrode electrolyte interface and reducing the ion transmission path; after adding an appropriate amount of amino polycarboxylate with electron-donating properties, the electron density around the PI and PVDF polymer molecules is increased, so that there are more nucleation sites in the polymer, the diameter of the polymer microspheres is reduced, the formation of a porous structure is inhibited, and a thinner and denser composite electrolyte film can be prepared.

[0039] In some embodiments of the present application, the polyvinylidene fluoride or its copolymer includes at least one of polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene (P(VDF-HFP)) copolymer, and polyvinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene (P(VDF-TrFE-CTFE)) terpolymer.

[0040] In some embodiments of the present application, the polyimide or its copolymer includes at least one of polyimide (PI), polyimide-siloxane block copolymer, and polylactic acid-polyimide block copolymer (PLA-PI-PLA).

[0041] In some embodiments of the present application, the melt viscosity of the polyvinylidene fluoride or its copolymer is denoted as η A , and the melt viscosity of the polyimide or its copolymer is denoted as η B , satisfying: η B - η A ≥ 500 cps. During film formation, the polyimide-based polymer (i.e., polyimide or its copolymer) with a higher viscosity and the polyvinylidene fluoride-based polymer (including polyvinylidene fluoride and polyvinylidene fluoride copolymer) with a lower viscosity tend to form a sea-island structure, the polyimide-based polymer with a higher viscosity can act as a nucleating agent together with the amino polycarboxylate, improve the crystallization properties of the polyvinylidene fluoride-based polymer, and help to improve the Young's modulus of the solid-state electrolyte film. η B - η A may be selected from 500 cps, 1000 cps, 2000 cps, or a range formed by any two of the values.

[0042] In some embodiments of the present application, further satisfying: 1.0 ≤ η B / η A ≤ 1.5. When the viscosity ratio of the polyimide and the polyvinylidene fluoride is within the above preferred range, the particle size of the "island" phase of the polyimide formed in the polyvinylidene fluoride-based matrix is smaller, which is more conducive to the role of the nucleating agent and helps to improve the Young's modulus of the solid-state electrolyte film; at the same time, the dispersion in the polyvinylidene fluoride-based matrix is more uniform, the ion transmission path is improved, and the conductivity of the electrolyte film is improved.B / η A The value of η can be selected from 1.0, 1.125, 1.17, 1.14, 1.33, or a range formed by any two of the values.

[0043] In some embodiments of the present application, the melt viscosity η of the polyvinylidene fluoride or the copolymer thereof is 3000-4000cps. A In the viscosity range, the electrolyte membrane has good flow casting film forming performance. A The value of η can be selected from 3000cps, 3500cps, 4000cps, or a range formed by any two of the values.

[0044] In some embodiments of the present application, the melt viscosity η of the polyimide or the copolymer thereof is 3500-5000cps. B In the viscosity range, the electrolyte membrane has good flow casting film forming performance. B The value of η can be selected from 3500cps, 4000cps, 4000cps, 5000cps, or a range formed by any two of the values.

[0045] In some embodiments of the present application, the number of carboxyl groups in the amino polycarboxylate is 5-6, and specifically, diethylenetriamine pentaacetic acid (DTPA), ethylenediaminetetraacetic acid (EDTA), hydroxyethyl ethylenediamine triacetic acid (HEDTA), ethylene glycol diethyl ether diamine tetraacetic acid (EGTA), nitrilotriacetic acid (NTA) can be preferably used. The carboxyl group is an electron-withdrawing group, and with the increase of the content of the carboxyl group, the ionic conductivity of the solid electrolyte membrane can be improved, but the adsorption capacity of the lithium salt will also be stronger, and the agglomeration is easy to occur, causing the interface to be loose and porous, the polarization to be large, and the loose and porous caused by low PI cannot be alleviated, thereby reducing the ionic conductivity of the solid electrolyte membrane. Therefore, when the content of the carboxyl group is in the above suitable range, the ionic conductivity is suitable, and the agglomeration with the lithium salt can be prevented. In some embodiments of the present application, the electrolyte salt includes at least one of sodium bis(trifluoromethylsulfonyl)imide (NaTFSI) and sodium hexafluorophosphate (NaPF6).

[0046] In some embodiments of the present application, a film forming agent can also be added as needed, and the film forming agent includes but is not limited to at least one of perfluorobenzene, 3-iodooxetane, and difluorocarbonic acid ethylene ester.

[0047] In a second aspect of the present application, a preparation method of the solid electrolyte membrane of the first aspect of the present application is provided, including the following steps:

[0048] According to the weight parts, polyvinylidene fluoride or a copolymer thereof, polyimide or a copolymer thereof, and an electrolyte salt are dissolved in an organic solvent to be uniformly mixed, and then an aminopolycarboxylate and a film-forming agent (if any) are added to be dissolved to obtain a mixed solution, a precursor film is obtained by a casting method, and the solid-state electrolyte film is obtained by drying.

[0049] In some embodiments of the present application, the temperature for dissolving is 60-160°C, which can be selected according to the type of raw material and the type of solvent, and each component can be dissolved.

[0050] In some embodiments of the present application, the temperature for drying is 80-100°C.

[0051] Any good solvent for the raw material of the electrolyte film known in the art can be used in the present application. In some embodiments of the present application, the organic solvent includes, but is not limited to, at least one of trimethyl phosphate (TMP), triethyl phosphate (TEP), triphenyl phosphate (TPP), and N,N-dimethylformamide (DMF).

[0052] In some embodiments of the present application, in the mixed solution, the weight of the film-forming agent is denoted as N2, and the weight of the organic solvent is denoted as N1, and the following condition is satisfied: 5%≤N2 / (N1+N2)≤20%. In this concentration range, the mixed solution for film formation has good uniformity and flowability, and a precursor film with uniform thickness can be obtained by coating.

[0053] In some embodiments of the present application, the specific operation of the casting method is as follows: the obtained mixed solution is deposited on a glass plate, and a doctor blade with adjustable height is used for coating to obtain a precursor film with uniform thickness.

[0054] In a third aspect of the present application, a secondary battery is provided, which includes a positive electrode sheet, the solid-state electrolyte film of the first aspect of the present application, and a negative electrode sheet.

[0055] The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer provided on at least one surface of the positive electrode current collector, and the positive electrode active material layer contains a positive electrode active material.

[0056] The negative electrode sheet includes a negative electrode current collector and a negative electrode active material layer provided on at least one surface of the negative electrode current collector, and the negative electrode active material layer contains a negative electrode active material.

[0057] The types of the negative electrode current collector and the positive electrode current collector are not particularly limited and can be selected according to actual needs.

[0058] The negative electrode current collector preferably can use a copper foil or a carbon-coated copper foil, etc.

[0059] The positive current collector can include, but is not limited to, aluminum, stainless steel, nickel plating, titanium, tantalum, and other metal materials; carbon cloth, carbon paper, and other carbon materials; a composite material formed by a polymer and a metal layer. In some embodiments, the positive current collector preferably uses an aluminum foil.

[0060] The type of negative active material is also not limited, and common negative active materials in the art, such as carbon, silicon, silicon-carbon composite negative active materials, etc., can be used in the present application, which can be selected according to actual needs.

[0061] In addition, at least one of a conductive agent, a binder, and a thickening agent is further included in the negative active material layer and the positive active material layer.

[0062] The conductive agent, the binder, and the thickening agent commonly used in the art can be used in the present application.

[0063] In some embodiments, the conductive agent includes, but is not limited to, at least one of graphite, carbon black, acetylene black, ketjen black, carbon nanotubes, and graphene.

[0064] In some embodiments, the binder includes, but is not limited to, at least one of styrene butadiene rubber, polyacrylic acid, polyacrylonitrile, polyvinylidene fluoride, polyvinylidene fluoride-tetrafluoroethylene copolymer, and polyvinylidene fluoride-hexafluoropropylene copolymer.

[0065] In some embodiments, the thickening agent includes, but is not limited to, at least one of sodium carboxymethyl cellulose and lithium carboxymethyl cellulose.

[0066] In some embodiments, the type of solvent used to form the positive electrode slurry and / or the negative electrode slurry is not limited, as long as it is a solvent capable of dissolving or dispersing the positive active material, the negative active material, the conductive agent, the binder, and the dispersing agent.

[0067] In some embodiments, the preparation of the secondary battery includes: stacking the positive electrode sheet, the solid-state electrolyte film, and the negative electrode sheet in order, so that the solid-state electrolyte film is between the positive electrode sheet and the negative electrode sheet to play a role of isolation, and assembling the secondary battery.

[0068] In a fourth aspect of the present application, a kind of electric equipment is provided, including the secondary battery of the third aspect of the present application.

[0069] The following are specific embodiments of the present application, and the technical solutions of the present application are further described in conjunction with the embodiments, but the present application is not limited to these embodiments. The reagents, methods and equipment used in the present application, such as no special description, are conventional reagents, methods and equipment in the technical field.

[0070] Examples 1-13, Comparative Examples 1-5

[0071] A solid electrolyte membrane is provided, which is prepared according to a method comprising the following steps:

[0072] According to the formulations shown in Table 1 and Table 2 (the numbers represent parts by weight), polyvinylidene fluoride or its copolymer, polyimide or its copolymer, electrolyte salt are dissolved into an organic solvent and mixed uniformly, then amino polycarboxylic acid salt (in Comparative Examples 4 and 5, it is replaced by the corresponding 4-aminobenzoic acid and hydroxybenzotriazole) and a film-forming agent are added, after stirring and dissolving at 60-160°C, a mixed solution is obtained (in the mixed solution, N2 / (N1+N2)=5% is satisfied, wherein the weight of the film-forming agent is denoted as N2, and the weight of the organic solvent is denoted as N1), a precursor thin film is obtained by using a casting method, vacuum drying is performed at a temperature of 80-100°C until the constant weight is reached, and a solid electrolyte membrane with a thickness of 10±2 μm is obtained.

[0073] Table 1

[0074]

[0075] In Table 1, η A represents the melt viscosity of the polyvinylidene fluoride or its copolymer; η B represents the melt viscosity of the polyimide or its copolymer, which is obtained by a rotary viscometer test.

[0076] Table 2

[0077] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 P(VDF-HFP) 100 65 50 65 65 65 PI / 35 50 35 35 35 EDTA 1 / / / / 1 4-aminobenzoic acid / / / 1 / / hydroxybenzotriazole / / / / 1 / NaTFSI 19 19 19 19 19 19 perfluorobenzene 1 1 1 1 1 /

[0078] In Table 2, unless otherwise specified, the selection of P(VDF-HFP) and PI molecular weight is the same as that in Example 5.

[0079] Example 15

[0080] A solid electrolyte membrane is provided, which is prepared according to the method of Example 1, and the difference from Example 1 is that in the mixed solution formed by the reaction raw materials, N2 / (N1+N2)=10% is satisfied, wherein the weight of the film-forming agent is denoted as N2, and the weight of the organic solvent is denoted as N1.

[0081] Example 16

[0082] A solid electrolyte membrane is provided, which is prepared according to the method of Example 1, and the difference from Example 1 is that in the mixed solution formed by the reaction raw materials, N2 / (N1+N2)=15% is satisfied, wherein the weight of the film-forming agent is denoted as N2, and the weight of the organic solvent is denoted as N1.

[0083] Example 17

[0084] A solid-state electrolyte film is provided, which is prepared according to the method of Example 1, except that in the mixed solution formed by the reaction raw materials, N2 / (N1+N2) = 20% is satisfied, where the weight of the film-forming agent is denoted as N2, and the weight of the organic solvent is denoted as N1.

[0085] Example 18

[0086] A solid-state electrolyte film is provided, which is prepared according to the method of Example 1, except that in the mixed solution formed by the reaction raw materials, N2 / (N1+N2) = 25% is satisfied, where the weight of the film-forming agent is denoted as N2, and the weight of the organic solvent is denoted as N1.

[0087] Performance test

[0088] The performance of the electrolyte films prepared in the above examples and comparative examples is tested, and the relevant test indicators and test methods are as follows, and the test results are shown in Table 3:

[0089] (1) Young's modulus (unit: GPa): according to the standard "ASTM D638-2014", the tensile properties of the electrolyte are tested, and the specific test temperature is 25±1℃, and the tensile rate is 50mm / min.

[0090] (2) Room temperature (25±1℃) ionic conductivity: the electrolyte film is punched into a circular piece with a diameter of 16mm and its thickness L and area S are measured, then it is assembled into a steel-steel (SS / SPE / SS) symmetric cell, the ohmic resistance R1 of the electrolyte film is tested by EIS (0.1Hz-100kHz), and the ionic conductivity is calculated by the formula

[0091] (3) Cycle performance of the battery

[0092] A secondary battery is prepared, and then the kinetic performance of the secondary battery is tested, wherein the preparation of the secondary battery comprises the following steps:

[0093] Preparation of positive electrode sheet

[0094] The positive active material, the conductive agent acetylene black, the dispersant PVP, and the binder polyvinylidene fluoride are dispersed in NMP according to a mass ratio of 97:0.8:0.4:1.8 to prepare a slurry, which is then coated on a 12μm aluminum foil, and after baking, rolling, and cutting, a positive electrode sheet (areal density 0.22g / 1540.25mm 2 ) is obtained.

[0095] Preparation of negative electrode sheet

[0096] ​When the added electrolyte salt in the solid-state electrolyte film is NaTFSI, a sodium metal negative electrode sheet is selected as the negative electrode;

[0097] Assembly of button half-cell

[0098] The positive electrode sheet, the solid-state electrolyte film prepared in the above examples or comparative examples, and the negative electrode sheet are sequentially stacked to assemble a button-type half battery.

[0099] The assembled button-type half battery is first charged at a rate of 1C to 4.1V, then charged at a rate of 1C to 2.5V, and cycled for 600 times, and the cycle capacity retention rate is calculated as the discharge capacity after 600 cycles / the initial discharge capacity*100%. The test results are shown in Table 3.

[0100] Table 3

[0101]

[0102]

[0103] From the above results, it can be seen that:

[0104] The solid-state electrolyte film is prepared with polyvinylidene fluoride or its copolymer as the matrix, and polyimide and ethylenediaminetetraacetic acid are added to improve the crystallization performance of polyvinylidene fluoride, so as to obtain a dense, high Young's modulus, and flame-retardant composite polymer electrolyte film. The solid-state electrolyte film prepared in the present application has a Young's modulus of ≥9.5GPa at a thickness of 10μm, an ionic conductivity of >4*10 -4 S / cm at 25℃, and a capacity retention rate of >85% after 600 cycles at 1C.

[0105] It should be noted that the amount of the polymer matrix is fixed, and different types and amounts of additives are added in the polymer matrix to improve the performance of the solid-state electrolyte film. The amount of the additive (such as electrolyte salt, amino polycarboxylate) is added based on 100 parts by weight of the polymer matrix.

[0106] The results of Comparative Example 6 and Examples 1, 15-18 show that when the composite electrolyte film does not contain perfluorobenzene, the phosphate groups remaining in the electrolyte during cycling and under high pressure conditions continuously and severely react with the positive and negative electrode sheets, and the active sodium ions are rapidly consumed, causing the capacity of the battery to rapidly decrease. In Examples 1, 15-18, as the content of perfluorobenzene increases, the cycle stability of the battery is also significantly improved, which is mainly due to the formation of an appropriate amount of uniform and strong electrolyte interface layer (SEI / CEI) on the positive and negative electrode surfaces, which greatly inhibits the destruction of the positive and negative electrodes by the phosphate. When the content of perfluorobenzene exceeds 20%, the cycle stability of the battery will also decrease to some extent, which is mainly due to the excessive formation of the SEI film, the increase in thickness and the increase in interface impedance, which causes the ion transmission at the interface to be blocked.

[0107] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not a limitation on the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. A solid-state electrolyte membrane, characterized by, The solid electrolyte membrane comprises the following components by weight: 100 parts of a polymer matrix, 15-20 parts of an electrolyte salt, 0.1-5 parts of a film-forming agent, and 1-5 parts of an amino polycarboxylate; the polymer matrix comprises polyvinylidene fluoride or a copolymer thereof, polyimide or a copolymer thereof; The polymer matrix satisfies 30%≤M2 / (M1+M2)≤45%, wherein M1 represents the weight parts of polyvinylidene fluoride or a copolymer thereof, and M2 represents the weight parts of polyimide or a copolymer thereof.

2. The solid-state electrolyte film of claim 1, wherein, The polyvinylidene fluoride or a copolymer thereof comprises at least one of polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, and polyvinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene terpolymer; and the polyimide or a copolymer thereof comprises at least one of polyimide, polyimide-siloxane block copolymer, and polylactic acid-polyimide block copolymer.

3. The solid-state electrolyte film of claim 1, wherein, The melt viscosity of the polyvinylidene fluoride or the copolymer thereof is denoted as η A The melt viscosity of the polyimide or the copolymer thereof is denoted as η B , and satisfies: η B - η A ≥ 500 cps.

4. The solid-state electrolyte film of claim 3, wherein, At least one of the following characteristics is satisfied: (1) η A = 3000-4000 cps; (2) η B = 3500-5000 cps; (3) 1.0 < η B / η A ≤ 1.

5.

5. The solid-state electrolyte film of claim 1, wherein The electrolyte salt comprises at least one of sodium bis(trifluoromethylsulfonyl)imide and sodium hexafluorophosphate; and / or the number of carboxyl groups in the amino polycarboxylate is 5-6.

6. The method of producing a solid-state electrolyte film according to any one of claims 1 to 5, characterized by, The method comprises the following steps: The polyvinylidene fluoride or a copolymer thereof, the polyimide or a copolymer thereof, and the electrolyte salt are dissolved in an organic solvent to be uniformly mixed, and then the amino polycarboxylate is added to obtain a mixed solution by dissolution; a precursor film is obtained by using a casting method, and the solid electrolyte membrane is obtained by drying.

7. The method of claim 6, wherein the solid-state electrolyte film is prepared by a method comprising: At least one of the following conditions is satisfied: (1) The organic solvent comprises at least one of trimethyl phosphate, triethyl phosphate, triphenyl phosphate, and N,N-dimethylformamide; (2) The temperature for dissolution is 60-160°C; (3) The temperature for drying is 80-100°C.

8. A secondary battery characterized by comprising: The secondary battery comprises a positive electrode sheet, the solid electrolyte membrane according to any one of claims 1-5, and a negative electrode sheet.

9. An electric device, characterized by The secondary battery comprises the secondary battery according to claim 8.

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