Solid electrolyte fiber diaphragm as well as preparation method and application thereof

Abstract

The invention relates to the field of solid-state lithium batteries, and discloses a solid-state electrolyte fiber diaphragm and a preparation method and application thereof.The solid-state electrolyte fiber diaphragm is composed of fiber yarn units which are distributed in a miscellaneous sequence and staggered mode, each fiber yarn unit contains an ammoxime lithium salt polymer, and the ammoxime lithium salt polymer contains a structural unit shown in the formula (1), the diaphragm provided by the invention has better comprehensive performance, and particularly has high ionic conductivity at room temperature, good thermal stability and electrochemical performance. # imgabs0 #

Description

Technical Field

[0001] The present invention relates to the field of solid-state lithium batteries, and in particular to a solid-state electrolyte fiber diaphragm and a preparation method and application thereof. Background Art

[0002] All-solid-state lithium batteries replace flammable organic electrolytes with non-flammable solid electrolytes. They have the advantages of high safety and high energy density, and are considered to be the preferred direction for the next generation of new power batteries and energy storage batteries.

[0003] The current solid electrolyte membranes can be divided into two types: inorganic solid electrolyte membranes and polymer solid electrolyte membranes. Compared with inorganic solid electrolyte membranes, polymer electrolyte membranes are easier to process and are suitable for large-scale industrial production, with better development prospects. However, although the existing polymer electrolyte membranes have good safety, they have poor contact with electrodes, resulting in high interface impedance. At the same time, the room temperature ionic conductivity of most polymer electrolytes is low, about 10 -7 -10 -4 S / cm, which is difficult to meet the needs of lithium-ion batteries.

[0004] At present, polyethylene oxide is a polymer matrix material commonly used in polymer electrolytes. It has good compatibility with metallic lithium and can match lithium negative electrodes with high theoretical capacity, thereby greatly improving the energy density of the battery. However, its chemical window is low and it cannot match positive electrode materials above 4V, which limits the further improvement of the system's discharge voltage and energy density.

[0005] Therefore, there is an urgent need to provide a polymer solid electrolyte membrane with high room temperature ionic conductivity and excellent electrochemical performance. Summary of the invention

[0006] The purpose of the present invention is to overcome the above-mentioned defects of the prior art and to provide a polymer solid electrolyte fiber membrane with high room temperature ionic conductivity and excellent electrochemical properties. The obtained solid electrolyte fiber membrane also has excellent tensile strength and excellent comprehensive performance.

[0007] The first aspect of the present invention provides a solid electrolyte fiber membrane, which is composed of fiber filament units that are randomly and alternately distributed with each other, wherein the fiber filament units contain an amidoxime lithium salt polymer, and the amidoxime lithium salt polymer contains a structural unit represented by formula (1):

[0008]

[0009] Among them, in formula (1),

[0010] R1-R 10Each is independently selected from a single atom substituent, a polyatom substituent, or one of R1 and R2 is cyclized with one of R3 and R4 to form a carbocyclic ring, and one of R8 and R9 is cyclized with one of R6 and R7 to form a carbocyclic ring; the single atom substituent includes hydrogen atoms and isotopes thereof, and halogen atoms; the polyatom substituent includes substituted or unsubstituted C 1-15 Alkyl, substituted or unsubstituted C 1-15 Alkoxy, substituted or unsubstituted C 2-15 Alkenyl, substituted or unsubstituted C 2-15 Alkynyl, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 Aryloxy, ester, boronic acid, and R1-R 10 The optional substituents are each independently selected from fluorine, chlorine, nitrogen, sulfur, oxygen, hydroxyl, C 1-10 Alkyl, C 1-10 Alkoxy, C 6-20 At least one of the aromatic groups.

[0011] The second aspect of the present invention provides a method for preparing the solid electrolyte fiber separator described in the first aspect, the method comprising:

[0012] (1) electrospinning a spinning solution containing an amidoxime lithium salt polymer to obtain an electrospinning membrane, wherein the amidoxime lithium salt polymer contains a structural unit represented by formula (1);

[0013] (2) hot pressing the electrospun membrane to obtain a solid electrolyte fiber membrane.

[0014] The third aspect of the present invention provides the use of the solid electrolyte fiber membrane described in the first aspect in a solid-state lithium battery.

[0015] Compared with the prior art, the present invention has at least the following advantages:

[0016] The solid electrolyte fiber diaphragm provided by the present invention is a polymer solid electrolyte fiber diaphragm with high room temperature ionic conductivity and excellent electrochemical performance, and the obtained solid electrolyte fiber diaphragm also has excellent tensile strength and excellent comprehensive performance.

[0017] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0018] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0019] In this article, the following terms are explained first:

[0020] In the present invention, the C 1-15 The alkyl group refers to an alkyl group with a total carbon atom count of 1-15, including straight-chain alkyl groups and cycloalkyl groups, such as, but not limited to, methyl, ethyl, n-propyl, isopropyl, cyclopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, cyclobutyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, n-hexyl, isohexyl, cyclohexyl, etc. 1-10 Alkyl, C 1-8 The definition of alkyl is similar, except that the number of carbon atoms is different.

[0021] In the present invention, the C 1-15 The alkoxy group refers to an alkoxy group having a total of 1 to 15 carbon atoms, including straight chain alkoxy and cycloalkoxy groups, such as but not limited to methoxy, ethoxy, n-propoxy, isopropoxy, cyclopropoxy, n-butoxy, sec-butoxy, isobutoxy, tert-butoxy, cyclobutoxy, n-pentoxy, isopentoxy, neopentoxy, cyclopentoxy, n-hexoxy, isohexoxy, cyclohexyloxy, etc., C 1-10 Alkoxy, C 1-8 The definition of alkoxy is similar, except that the number of carbon atoms is different.

[0022] In the present invention, the C 2-15 Alkenyl refers to an alkenyl group having a total of 2-15 carbon atoms, including straight-chain alkene groups and cycloalkenyl groups, such as but not limited to ethenyl, propenyl, etc.

[0023] In the present invention, the C 2-15 Alkynyl refers to an alkynyl group having 2 to 15 carbon atoms, including straight chain alkynyl and cycloalkynyl, such as but not limited to ethynyl, propynyl and the like.

[0024] In the present invention, C 6-20 The aryl group refers to an aryl group having 6 to 20 carbon atoms, including but not limited to phenyl, naphthyl, anthracenyl, and the like.

[0025] In the present invention, C 6-20 The aryloxy group refers to an aryl group having a total of 6 to 20 carbon atoms, including but not limited to phenoxy.

[0026] According to the present invention, there are no particular limitations on the substitution position and the number of substitutions of each optionally present substituent, and any number of substitutions may be made at any substitutable position.

[0027] As mentioned above, the first aspect of the present invention provides a solid electrolyte fiber membrane, which is composed of fiber filament units that are randomly and alternately distributed with each other, and the fiber filament units contain an amidoxime lithium salt polymer, and the amidoxime lithium salt polymer contains a structural unit shown in formula (1):

[0028]

[0029] Among them, in formula (1),

[0030] R1-R 10 Each is independently selected from a single atom substituent, a polyatom substituent, or one of R1 and R2 is cyclized with one of R3 and R4 to form a carbocyclic ring, and one of R8 and R9 is cyclized with one of R6 and R7 to form a carbocyclic ring; the single atom substituent includes hydrogen atoms and isotopes thereof, and halogen atoms; the polyatom substituent includes substituted or unsubstituted C 1-15 Alkyl, substituted or unsubstituted C 1-15 Alkoxy, substituted or unsubstituted C 2-15 Alkenyl, substituted or unsubstituted C 2-15 Alkynyl, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 Aryloxy, ester, boronic acid, and R1-R 10 The optional substituents are each independently selected from fluorine, chlorine, nitrogen, sulfur, oxygen, hydroxyl, C 1-10 Alkyl, C 1-10 Alkoxy, C 6-20 At least one of the aromatic groups.

[0031] According to a preferred embodiment of the present invention, in formula (1), R1-R 10 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkoxy, substituted or unsubstituted C 2-10 Alkenyl, substituted or unsubstituted C 2-10 Alkynyl, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 At least one of the aryloxy groups, or one of R1 and R2 is cyclized with one of R3 and R4 to form a carbocyclic ring, one of R8 and R9 is cyclized with one of R6 and R7 to form a carbocyclic ring, and R1-R 10The optional substituents are each independently selected from fluorine, chlorine, nitrogen, sulfur, oxygen, hydroxyl, C 1-10 Alkyl, C 1-10 Alkoxy, C 6-20 At least one of the aromatic groups.

[0032] According to a more preferred embodiment of the present invention, R1-R 10 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkoxy, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 At least one of the aryloxy groups, or one of R1 and R2 is cyclized with one of R3 and R4 to form a carbocyclic ring, one of R8 and R9 is cyclized with one of R6 and R7 to form a carbocyclic ring, and R1-R 10 The optional substituents are each independently selected from fluorine, chlorine, nitrogen, sulfur, oxygen, hydroxyl, C 1-10 Alkyl, C 1-10 Alkoxy, C 6-20 At least one of the aromatic groups.

[0033] According to a further preferred embodiment of the present invention, R1-R 10 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1-8 Alkyl, substituted or unsubstituted C 1-8 Alkoxy, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 At least one of the aryloxy groups, or one of R1 and R2 and one of R3 and R4 together form a C 6-12 One of R8 and R9 is cyclized with one of R6 and R7 to form a carbon ring. 6-12 Carbon ring, and R1-R 10 The substituents optionally present in the amine are each independently selected from at least one of fluorine, chlorine, nitrogen, sulfur, hydroxyl, methyl, ethyl, methoxy, ethoxy and phenyl.

[0034] According to a more preferred embodiment of the present invention, R1, R2, R3, R4, R8, R9, R6, and R7 are each independently selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and phenyl; or, one of R1 and R2 is cyclized with one of R3 and R4 to form a benzene ring structure, and one of R8 and R9 is cyclized with one of R6 and R7 to form a benzene ring structure; R5, R 10Each is independently selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl and phenyl.

[0035] According to the present invention, one of R1 and R2 is cyclized with one of R3 and R4 to form a carbocyclic ring, and one of R8 and R9 is cyclized with one of R6 and R7 to form a carbocyclic ring, which means, for example, that one of R1 and R2 and one of R3 and R4 are bonded to each other and cyclized to form a carbocyclic structure such as a benzene ring structure, and the unbonded substituent may be present or absent depending on the bonding situation. For example, when the benzene ring structure is cyclized, the polymer comprises a structural unit as shown in the following formula (1I).

[0036] According to a further preferred embodiment of the present invention, the amidoxime lithium salt polymer contains structural units represented by formula (II) and formula (III):

[0037]

[0038] Preferably, the weight average molecular weight of the amidoxime lithium salt polymer is 50,000-200,000.

[0039] According to the present invention, the amidoxime lithium salt polymer can be prepared by the existing polymer preparation method in the art. Preferably, the amidoxime lithium salt polymer is prepared by the following method:

[0040] (A) subjecting monomer I and terephthalonitrile-based monomer II to a first reaction to obtain polymer I;

[0041] (B) subjecting polymer I to a second reaction with hydroxylamine to obtain polymer II;

[0042] (C) subjecting the polymer II to a third reaction with a lithium salt to obtain the amidoxime lithium salt polymer;

[0043] Wherein, the monomer I has a structure shown in formula (AI); the phthalonitrile compound has a structure shown in formula (AII); the polymer I contains a structural unit shown in formula (B); and the polymer II contains a structural unit shown in formula (C);

[0044]

[0045] Among them, in formula (AI), formula (AII), formula (B) and formula (C), R1-R 10 The definition of is as described in the first aspect above, and X1, X2, X3 and X4 are each independently selected from halogen atoms.

[0046] Preferably, in formula (AII), X1, X2, X3 and X4 are the same and are selected from fluorine, chlorine, bromine and iodine. More preferably, the terephthalonitrile monomer II is selected from at least one of tetrafluoroterephthalonitrile and tetrachloroterephthalonitrile, and further preferably is tetrafluoroterephthalonitrile.

[0047] Preferably, in step (C), the lithium salt is selected from at least one of lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perfluoroethanesulfonylimide and perfluoromethylsulfonylmethyl lithium.

[0048] Preferably, in step (A), the conditions of the first reaction include: temperature 50-100° C., time 12-72 h.

[0049] Preferably, in step (B), the conditions of the second reaction include: temperature 50-100° C., time 24-72 h.

[0050] Preferably, in step (C), the conditions of the third reaction include: temperature 20-80° C., time 6-24 h.

[0051] Preferably, in step (A), the first reaction is carried out in a first solvent, and the first solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone and butanone.

[0052] Preferably, in step (A), the first reaction is carried out in the presence of potassium carbonate, and the molar ratio of the monomer I to the potassium carbonate is 1:0.5-10.

[0053] Preferably, in step (B), the second reaction is carried out in a second solvent, and the second solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone and butanone.

[0054] According to the present invention, in step (B), the hydroxylamine can be added to the reaction system in the form of a hydroxylamine solution to participate in the reaction. Preferably, the hydroxylamine solution is a 30-70 wt % hydroxylamine aqueous solution.

[0055] Preferably, in step (B), the second reaction is carried out in a protective atmosphere, and the protective atmosphere is preferably nitrogen.

[0056] Preferably, in step (C), the third reaction is carried out in a third solvent, and the third solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone, butanone, and tetraethylene glycol dimethyl ether.

[0057] Preferably, in step (A), the molar ratio of the monomer I to the terephthalonitrile monomer II is 1:0.5-2.

[0058] and / or, in step (B), the weight ratio of the polymer I to the hydroxylamine is 1:0.01-5;

[0059] And / or, in step (C), the weight ratio of the polymer II to the lithium salt is 1:0.01-5.

[0060] According to the present invention, in step (A), the reaction mixture of the first reaction is mixed with deionized water for precipitation, and then the precipitate is washed and first dried to obtain the polymer I powder. Preferably, the first drying is carried out under vacuum conditions, and the conditions of the first drying include: a temperature of 50-100°C.

[0061] According to the present invention, in step (B), the reaction mixture of the second reaction is mixed with ethanol for precipitation, and then the precipitate is washed and dried for the second time to obtain the polymer II powder. Preferably, the second drying is carried out under vacuum conditions, and the conditions of the second drying include: a temperature of 30-110°C.

[0062] Preferably, the solid electrolyte separator has an average thickness of 20-40 μm.

[0063] Preferably, the average diameter of the fiber structure unit is 0.5-2 μm.

[0064] Preferably, the room temperature ionic conductivity of the solid electrolyte fiber membrane is 0.6-1.5 mS / cm, more preferably 0.8-1.5 mS / cm; the tensile strength is 20-45 MPa, preferably 30-45 MPa; and the thermal shrinkage is <5%, preferably <3%.

[0065] As mentioned above, the second aspect of the present invention provides a method for preparing the solid electrolyte fiber separator described in the first aspect, the method comprising:

[0066] (1) electrospinning a spinning solution containing an amidoxime lithium salt polymer to obtain an electrospinning membrane, wherein the amidoxime lithium salt polymer contains a structural unit represented by formula (1);

[0067] (2) hot pressing the electrospun membrane to obtain a solid electrolyte fiber membrane.

[0068] Preferably, in step (1), the electrospinning conditions include: spinning voltage of 10-30 kV, receiving distance of 10-30 cm, humidity of 20-60%, and temperature of 20-50°C.

[0069] Preferably, in step (2), the hot pressing conditions include: temperature 50-120° C., time 2-30 minutes.

[0070] Preferably, the solvent IV of the spinning solution containing the amidoxime lithium salt polymer is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone and butanone.

[0071] Preferably, the molar ratio of the amidoxime lithium salt polymer to the solvent IV is 1:1-10.

[0072] Preferably, the dissolution temperature of the amidoxime lithium salt polymer in the solvent IV is 25-100°C.

[0073] In the second aspect of the present invention, according to a preferred embodiment of the present invention, the method further comprises preparing the amidoxime lithium salt polymer by the following steps:

[0074] (A) subjecting monomer I and terephthalonitrile-based monomer II to a first reaction to obtain polymer I;

[0075] (B) subjecting polymer I to a second reaction with hydroxylamine to obtain polymer II;

[0076] (C) subjecting the polymer II to a third reaction with a lithium salt to obtain the amidoxime lithium salt polymer;

[0077] Wherein, the monomer I has a structure shown in formula (AI); the phthalonitrile compound has a structure shown in formula (AII); the polymer I contains a structural unit shown in formula (B); and the polymer II contains a structural unit shown in formula (C);

[0078]

[0079]

[0080] Among them, in formula (AI), formula (AII), formula (B) and formula (C), R1-R 10 The definition of is as described in the first aspect above, and X1, X2, X3 and X4 are each independently selected from halogen atoms.

[0081] Preferably, in formula (AII), X1, X2, X3 and X4 are the same and are selected from fluorine, chlorine, bromine and iodine. More preferably, the terephthalonitrile monomer II is selected from at least one of tetrafluoroterephthalonitrile and tetrachloroterephthalonitrile, and further preferably is tetrafluoroterephthalonitrile.

[0082] Preferably, in step (C), the lithium salt is selected from at least one of lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perfluoroethanesulfonylimide and perfluoromethylsulfonylmethyl lithium.

[0083] Preferably, in step (A), the conditions of the first reaction include: temperature 50-100° C., time 12-72 h.

[0084] Preferably, in step (B), the conditions of the second reaction include: temperature 50-100° C., time 24-72 h.

[0085] Preferably, in step (C), the conditions of the third reaction include: temperature 20-80° C., time 6-24 h.

[0086] Preferably, in step (A), the first reaction is carried out in a first solvent, and the first solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone and butanone.

[0087] Preferably, in step (A), the first reaction is carried out in the presence of potassium carbonate, and the molar ratio of the monomer I to the potassium carbonate is 1:0.5-10.

[0088] Preferably, in step (B), the second reaction is carried out in a second solvent, and the second solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone and butanone.

[0089] According to the present invention, in step (B), the hydroxylamine can be added to the reaction system in the form of a hydroxylamine solution to participate in the reaction. Preferably, the hydroxylamine solution is a 30-70 wt % hydroxylamine aqueous solution.

[0090] Preferably, in step (B), the second reaction is carried out in a protective atmosphere, and the protective atmosphere is preferably nitrogen.

[0091] Preferably, in step (C), the third reaction is carried out in a third solvent, and the third solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone, butanone, and tetraethylene glycol dimethyl ether.

[0092] Preferably, in step (A), the molar ratio of the monomer I to the terephthalonitrile monomer II is 1:0.5-2.

[0093] and / or, in step (B), the weight ratio of the polymer I to the hydroxylamine is 1:0.01-5;

[0094] And / or, in step (C), the weight ratio of the polymer II to the lithium salt is 1:0.01-5.

[0095] According to the present invention, in step (A), the reaction mixture of the first reaction is mixed with deionized water for precipitation, and then the precipitate is washed and first dried to obtain the polymer I powder. Preferably, the first drying is carried out under vacuum conditions, and the conditions of the first drying include: a temperature of 50-100°C.

[0096] According to the present invention, in step (B), the reaction mixture of the second reaction is mixed with ethanol for precipitation, and then the precipitate is washed and dried for the second time to obtain the polymer II powder. Preferably, the second drying is carried out under vacuum conditions, and the conditions of the second drying include: a temperature of 30-110°C.

[0097] The method described in the present invention includes conventional post-processing operations such as precipitation, washing, and drying, which are not particularly limited in the present invention and can be selected and set according to actual conditions. In addition, the present invention lists several specific operations in subsequent embodiments, which should not be understood by those skilled in the art as limitations of the present invention.

[0098] According to a preferred embodiment of the present invention, the method described in the second aspect of the present invention includes:

[0099] (1) dissolving monomer I and terephthalonitrile monomer II in solvent I, adding potassium carbonate thereto, stirring at 50-100° C. for 12-72 h for a first reaction; then pouring the reaction mixture into deionized water to precipitate a solid; washing the solid with water and methanol at room temperature, and then vacuum drying at 50-100° C. to obtain polymer I powder;

[0100] (2) Under nitrogen atmosphere, the polymer I is dissolved in solvent II, and a hydroxylamine aqueous solution is dripped thereinto, and stirred at 50-100°C for 24-72 hours for a second reaction; after cooling, the reaction solution is poured into ethanol to form a white precipitate. Under room temperature conditions, the white precipitate is thoroughly washed with methanol, and vacuum dried at 30-110°C for 6-48 hours to obtain polymer II powder;

[0101] (3) immersing polymer II in a lithium salt solution and reacting at 20-80° C. for 6-24 hours to perform a third reaction to obtain an amidoxime lithium salt polymer;

[0102] (4) dissolving the amidoxime lithium salt polymer in solvent IV to obtain an electrospinning solution; and electrospinning the electrospinning solution to obtain an electrospinning membrane I;

[0103] (5) hot pressing the electrospun membrane I to obtain a solid electrolyte fiber membrane.

[0104] As mentioned above, the third aspect of the present invention provides the use of the solid electrolyte fiber membrane described in the first aspect in a solid-state lithium battery.

[0105] In the present invention, unless otherwise specified, room temperature refers to 25±2° C. and pressure refers to gauge pressure.

[0106] The present invention will be described in detail below through examples. In the following examples, unless otherwise specified, all raw materials used are commercially available. Among them, monomer I: a1 was purchased from Alfa Aesar with a purity of 97%; a2 was purchased from Inotech with a purity of 98%.

[0107] Example 1

[0108]

[0109] (1) a1 (monomer I, 7.49 g, 22 mmol) and tetrafluoroterephthalic acid (monomer II, 4.4 g, 22 mmol) were added to a round-bottom flask and dissolved in 100 ml of DMF at 65°C. Potassium carbonate (12 g, 87 mmol) was slowly added and stirred at 65°C for 48 h for the first reaction. The reaction mixture was then poured into 500 ml of water to precipitate a solid. The solid was washed with water and methanol at room temperature for 3 times each and dried in vacuo at 65°C to obtain b1;

[0110]

[0111] (2) Under nitrogen atmosphere, b1 (5.00 g) and THF (380 mL) were added to a round-bottom flask, the mixture was heated to 60°C to dissolve the polymer, 10 ml of hydroxylamine solution (50 wt% aqueous solution) was dripped into it, and stirred at 60°C for 24 h for the second reaction (the mass ratio of b1 to hydroxylamine reaction was 1:1); after cooling, the above reaction solution was poured into ethanol to form a precipitate. Under room temperature conditions, the above precipitate was thoroughly washed with methanol and vacuum dried at 50°C for 24 h to obtain c1.

[0112]

[0113] (3) At 25° C., c1 was immersed in a 1 mol / L lithium salt solution (lithium salt is lithium bis(trifluoromethanesulfonyl)imide and solvent is tetraethylene glycol dimethyl ether) for 12 hours to carry out a third reaction (mass ratio of c1 to lithium salt is 1:1) to obtain an amidoxime lithium salt polymer d1 with a molecular weight Mw=150,000;

[0114] (4) dissolving d1 in DMF solvent at a molar ratio of 1:5 and a dissolution temperature of 60°C to obtain an electrospinning solution; subjecting the electrospinning solution to electrospinning, wherein the electrospinning conditions include: a spinning voltage of 20 kV, a receiving distance of 20 cm, a humidity of 40%, and a temperature of 40°C; obtaining an electrospinning membrane I, wherein the average diameter of the fiber structure unit is 1 μm;

[0115] (5) The electrospun membrane I is hot pressed, and the hot pressing conditions include: the hot pressing temperature is 70° C. and the hot pressing time is 10 minutes; and a solid electrolyte fiber membrane is obtained with an average thickness of 25 μm.

[0116] Example 2

[0117]

[0118] (1) a2 (7.49 g, 22 mmol) and tetrafluoroterephthalic acid (4.4 g, 22 mmol) were added to a round-bottom flask, dissolved in 100 ml of DMF at 65°C, potassium carbonate (12 g, 87 mmol) was slowly added, and stirred at 65°C for 48 h for the first reaction. The reaction mixture was then poured into 500 ml of water to precipitate a solid. The solid was washed with water and methanol 3 times each at room temperature, and dried in vacuo at 65°C to obtain b2;

[0119]

[0120] (2) In a nitrogen atmosphere, b2 (5.00 g, 10 mmol) and dimethyl sulfoxide (300 mL) were added to a round-bottom flask, and the mixture was heated to 60°C to dissolve the polymer. 10 ml of hydroxylamine solution (50 wt% aqueous solution) was dripped into it, and stirred at 60°C for 24 h for the second reaction (the mass ratio of b1 to hydroxylamine reaction was 1:1); after cooling, the above reaction solution was poured into ethanol to form a precipitate. Under room temperature conditions, the above precipitate was thoroughly washed with methanol and vacuum dried at 60°C for 24 h to obtain c2.

[0121]

[0122] (3) At 25°C, c2 was immersed in a 1 mol / L lithium salt solution (lithium salt is lithium bis(trifluoromethanesulfonyl)imide, solvent is tetraethylene glycol dimethyl ether) for 12 hours to carry out a third reaction (mass ratio of c1 to lithium salt is 1:1) to obtain an amidoxime lithium salt polymer d2; molecular weight Mw = 130,000.

[0123] (4) dissolving d2 in dimethyl sulfoxide solvent at a molar ratio of 1:5 and a dissolution temperature of 60° C. to obtain an electrospinning solution; subjecting the electrospinning solution to electrospinning, wherein the electrospinning conditions include: a spinning voltage of 25 kV, a receiving distance of 25 cm, a humidity of 40%, and a temperature of 40° C. to obtain an electrospinning membrane I, wherein the average diameter of the fiber structure unit is 1 μm;

[0124] (5) The electrospun membrane I is hot pressed, and the hot pressing conditions include: the hot pressing temperature is 80° C. and the hot pressing time is 7 minutes; and a solid electrolyte fiber membrane is obtained with an average thickness of 25 μm.

[0125] Example 3

[0126] A solid electrolyte fiber membrane was prepared in a manner similar to that in Example 1, except that monomer I in step (1) was replaced by an equimolar amount of a3 (the structure of a3 is shown below, purchased from Inotech Corporation), and the rest was the same as in Example 1 to obtain a solid electrolyte fiber membrane.

[0127]

[0128] Example 4

[0129] A solid electrolyte fiber membrane was prepared in a manner similar to Example 1, except that monomer I in step (1) was replaced by an equimolar amount of a4 (the structure of a4 is shown below, purchased from Inotech Corporation), and the rest was the same as Example 1 to obtain a solid electrolyte fiber membrane.

[0130]

[0131] Example 5

[0132] A solid electrolyte fiber membrane was prepared in a manner similar to that in Example 1, except that monomer I in step (1) was replaced by an equimolar amount of a5 (structure shown below, purchased from Inotech Corporation), and the rest was the same as in Example 1 to obtain a solid electrolyte fiber membrane.

[0133]

[0134] Comparative Example 1

[0135] A similar method to Example 1 is used, except that step (2) is not performed, and b1 obtained in step (1) is directly immersed in a 1 mol / L lithium salt solution for 12 hours to obtain a lithium salt polymer f1; then, electrospinning and hot pressing are performed in the same manner as in Example 1 to obtain a solid electrolyte membrane.

[0136] Test Case

[0137] 1. The following properties of the solid electrolyte membranes obtained in the above embodiments and comparative examples were tested. The test results are shown in Table 1 below.

[0138] (1) Ionic conductivity: The ionic conductivity of the diaphragm was measured using an electrochemical workstation. The test frequency range was 0.001 Hz to 10 5 Hz, the test temperature is room temperature (25°C), and then the conductivity (σ) is calculated according to the formula. The specific results are shown in the table below:

[0139]

[0140] Where, σ is the ionic conductivity of the membrane (S / cm), d is the thickness of the membrane (cm), R b is the bulk resistance of the diaphragm (Ω), A is the effective contact area between the diaphragm and the electrode (cm 2 ).

[0141] (2) Tensile strength: The tensile strength of the solid electrolyte fiber diaphragm prepared in the above example was tested using the plastic tensile test method of GB1040-79;

[0142] (3) Thickness: Use a thickness gauge (accuracy 0.1 μm) to test the thickness. Randomly select 5 points on the sample and take the average value.

[0143] (4) Thermal shrinkage: The thermal shrinkage of the dimensions was measured in an oven. The sample was heat treated at 130°C for 1 h, and then the thermal shrinkage (δ) was calculated according to the formula:

[0144]

[0145] Among them, S1 and S2 are the areas of the diaphragm before and after heat treatment;

[0146] Table 1

[0147] Examples Thickness / μm Ionic conductivity / mS / cm Tensile strength / MPa Thermal shrinkage Example 1 25 1.05 43 ＜3％ Example 2 25 0.99 40 ＜3％ Example 3 25 0.83 38 ＜3％ Example 4 25 0.62 33 ＜3％ Example 5 25 0.6 31 ＜3％ Comparative Example 1 25 0.51 5 ＜3％

[0148] 2. The solid electrolyte fiber membranes obtained in the above embodiments and comparative examples were assembled into solid-state lithium batteries, and the following performances of the batteries were tested. The test results are shown in Table 2 below.

[0149] Preparation of solid-state lithium batteries:

[0150] The positive electrode formula is lithium iron phosphate: conductive carbon black: binder (PVDF) = 80:10:10, and the negative electrode is lithium metal. The battery is assembled in the order of negative electrode shell, lithium metal negative electrode, solid electrolyte composite diaphragm, positive electrode, and positive electrode shell. The solid-state lithium battery is charged and discharged at a rate of 0.2C.

[0151] Table 2

[0152] Examples First discharge capacity / mAh / g Capacity retention rate after 200 cycles at 0.2C / % Example 1 151 93 Example 2 148 92 Example 3 146 89 Example 4 136 88 Example 5 137 88 Comparative Example 1 122 83

[0153] It can be seen from the above results that the diaphragm provided by the present invention has better comprehensive performance, especially high ionic conductivity at room temperature, good thermal stability and electrochemical performance.

[0154] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A solid electrolyte fiber membrane, characterized in that the solid electrolyte fiber membrane is composed of fiber filament units that are randomly and alternately distributed with each other, wherein the fiber filament units contain an amidoxime lithium salt polymer, and the amidoxime lithium salt polymer contains a structural unit represented by formula (1): in, In formula (1), R1-R 10 Each is independently selected from a single atom substituent, a polyatom substituent, or one of R1 and R2 is cyclized with one of R3 and R4 to form a carbocyclic ring, and one of R8 and R9 is cyclized with one of R6 and R7 to form a carbocyclic ring; the single atom substituent includes hydrogen atoms and isotopes thereof, and halogen atoms; the polyatom substituent includes substituted or unsubstituted C 1-15 Alkyl, substituted or unsubstituted C 1-15 Alkoxy, substituted or unsubstituted C 2-15 Alkenyl, substituted or unsubstituted C 2-15 Alkynyl, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 Aryloxy, ester, boronic acid, and R1-R 10 The optional substituents are each independently selected from fluorine, chlorine, nitrogen, sulfur, oxygen, hydroxyl, C 1-10 Alkyl, C 1-10 Alkoxy, C 6-20 At least one of the aromatic groups.

2. The solid electrolyte fiber membrane according to claim 1, wherein: In formula (1), R1-R 10 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkoxy, substituted or unsubstituted C 2-10 Alkenyl, substituted or unsubstituted C 2-10 Alkynyl, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 At least one of the aryloxy groups, or one of R1 and R2 is cyclized with one of R3 and R4 to form a carbocyclic ring, one of R8 and R9 is cyclized with one of R6 and R7 to form a carbocyclic ring, and R1-R 10 The optional substituents are each independently selected from fluorine, chlorine, nitrogen, sulfur, oxygen, hydroxyl, C 1-10 Alkyl, C 1-10 Alkoxy, C 6-20 At least one of the aromatic groups; Preferably, R1-R 10 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1-10 Alkyl, substituted or unsubstituted C 1-10 Alkoxy, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 At least one of the aryloxy groups, or one of R1 and R2 is cyclized with one of R3 and R4 to form a carbocyclic ring, one of R8 and R9 is cyclized with one of R6 and R7 to form a carbocyclic ring, and R1-R 10 The optional substituents are each independently selected from fluorine, chlorine, nitrogen, sulfur, oxygen, hydroxyl, C 1-10 Alkyl, C 1-10 Alkoxy, C 6-20 At least one of the aromatic groups; More preferably, R1-R 10 are each independently selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted C 1-8 Alkyl, substituted or unsubstituted C 1-8 Alkoxy, substituted or unsubstituted C 6-20 Aryl, substituted or unsubstituted C 6-20 At least one of the aryloxy groups, or one of R1 and R2 is cyclized with one of R3 and R4 to form a carbon ring, one of R8 and R9 is cyclized with one of R6 and R7 to form a benzene ring, and R1-R 10 The optional substituents are each independently selected from at least one of fluorine, chlorine, nitrogen, sulfur, oxygen, hydroxyl, methyl, ethyl, methoxy, ethoxy and phenyl; More preferably, R1, R2, R3, R4, R6, R7, R8, and R9 are each independently selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, and phenyl; or, one of R1 and R2 is cyclized with one of R3 and R4 to form a benzene ring structure, and one of R8 and R9 is cyclized with one of R6 and R7 to form a benzene ring structure; R5, R 10 Each is independently selected from H, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl and phenyl.

3. The solid electrolyte fiber membrane according to claim 1, wherein: The weight average molecular weight of the amidoxime lithium salt polymer is 50,000-200,000.

4. The solid electrolyte fiber membrane according to any one of claims 1 to 3, wherein: The average thickness of the solid electrolyte fiber separator is 20-40 microns; And / or, the room temperature ionic conductivity of the solid electrolyte fiber membrane is 0.6-1.5 mS / cm, preferably 0.8-1.5 mS / cm; the tensile strength is 20-45 MPa, preferably 30-45 MPa; the thermal shrinkage is <5%, preferably <3%.

5. A method for preparing the solid electrolyte fiber membrane according to any one of claims 1 to 4, characterized in that: The method includes: (1) electrospinning a spinning solution containing an amidoxime lithium salt polymer to obtain an electrospinning membrane, wherein the amidoxime lithium salt polymer contains a structural unit represented by formula (1); (2) hot pressing the electrospun membrane to obtain a solid electrolyte fiber membrane.

6. The method according to claim 5, wherein: In step (1), the electrospinning conditions include: spinning voltage of 10-30 kV, receiving distance of 10-30 cm, humidity of 20-60%, and temperature of 20-50° C.; And / or, in step (2), the hot pressing conditions include: temperature 50-120° C., time 2-30 minutes.

7. The method according to claim 5 or 6, wherein: The method further comprises preparing the amidoxime lithium salt polymer by the following steps: (A) subjecting monomer I and terephthalonitrile-based monomer II to a first reaction to obtain polymer I; (B) subjecting polymer I to a second reaction with hydroxylamine to obtain polymer II; (C) subjecting the polymer II to a third reaction with a lithium salt to obtain the amidoxime lithium salt polymer; Wherein, the monomer I has a structure shown in formula (AI); the phthalonitrile compound has a structure shown in formula (AII); the polymer I contains a structural unit shown in formula (B); and the polymer II contains a structural unit shown in formula (C); Among them, in formula (AI), formula (AII), formula (B) and formula (C), R1-R 10 As defined in any one of claims 1 to 4, X1, X2, X3 and X4 are each independently selected from halogen atoms.

8. The method according to claim 7, wherein: In formula (AII), X1, X2, X3 and X4 are the same and are selected from fluorine, chlorine, bromine and iodine; Preferably, the terephthalonitrile monomer II is selected from at least one of tetrafluoroterephthalonitrile and tetrachloroterephthalonitrile, more preferably tetrafluoroterephthalonitrile; And / or, in step (C), the lithium salt is selected from at least one of lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethanesulfonyl)amide, lithium bis(fluorosulfonyl)imide, lithium perfluoroethanesulfonylimide and perfluoromethylsulfonylmethyl lithium.

9. The method according to claim 7 or 8, wherein: In step (A), the conditions of the first reaction include: temperature 50-100° C., time 12-72 h; And / or, in step (B), the conditions of the second reaction include: temperature 50-100°C, time 24-72h; And / or, in step (C), the conditions of the third reaction include: temperature 20-80°C, time 6-24h.

10. The method according to any one of claims 7 to 9, wherein: In step (A), the first reaction is carried out in a first solvent, and the first solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone, and butanone; and / or, in step (B), the second reaction is carried out in a second solvent, the second solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone and butanone; And / or, in step (C), the third reaction is carried out in a third solvent, and the third solvent is selected from at least one of N,N-dimethylformamide, tetrahydrofuran, chloroform, dichloromethane, dimethyl sulfoxide, methanol, ethanol, acetone, and butanone.

11. The method according to any one of claims 7 to 10, wherein: In step (A), the molar ratio of the monomer I to the terephthalonitrile monomer II is 1:0.5-2; and / or, in step (B), the weight ratio of the polymer I to the hydroxylamine is 1:0.01-5; And / or, in step (C), the weight ratio of the polymer II to the lithium salt is 1:0.01-5.

12. Use of the solid electrolyte fiber separator according to any one of claims 1 to 4 in a solid-state lithium battery.

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