Crosslinked polymers and methods of making, electrolyte compositions, polymer electrolytes and methods of making, lithium ion batteries and electrical devices

Abstract

The application relates to the field of lithium ion batteries and discloses a crosslinked polymer, characterized in that the crosslinked polymer comprises macromolecular chains A from a compound a shown in formula (1), crosslinked structures B from a compound b shown in formula (2), and a connecting group -NH- connecting the macromolecular chains A and the crosslinked structures B; wherein the macromolecular chains A comprise polyether flexible chain segments; the crosslinked polymer has a composite structure of hydrogen bonds and covalent bonds, wherein the covalent bond is -CN-, and the hydrogen bond is formed by complexing the hydrogen atom of the amino group in the compound b with the double bond oxygen atom on the nitrogen-containing heterocyclic ring in the compound a; wherein R1 and R2 are each independently H, a C1-C6 straight-chain alkyl group or a C3-C6 branched-chain alkyl group; m is an integer of 1-100, and n is an integer of 1-100; the application provides a polymer electrolyte with high mechanical strength, high toughness, high elasticity, high ion conductivity, good thermal stability and high interface stability.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium ion batteries, and in particular to a cross-linked polymer and a preparation method thereof, an electrolyte composition, a polymer electrolyte and a preparation method thereof, a lithium ion battery and electrical equipment. Background Art

[0002] Lithium-ion batteries, with their high operating voltage, high specific energy, lack of memory effect, long cycle life, and low self-discharge, are ideal power sources for a wide range of electronic products and are also ideal lightweight, high-energy power sources for future electric vehicles. However, current commercial lithium-ion batteries face safety risks such as poor electrolyte compatibility between the separator and the electrolyte, as well as potential explosion risks from liquid electrolyte leakage. Therefore, enhancing the compatibility between the separator and the electrolyte is a current research hotspot. Polymer electrolytes, by integrating the separator and electrolyte, effectively avoid this problem. Furthermore, their high plasticity facilitates battery design and assembly, meeting the growing demand for miniaturized, thinner, and lighter electronic products.

[0003] Current research and technology mainly focus on improving the ionic conductivity of lithium batteries by changing the structure of polymers. Existing research uses grafted polymers with a main chain of polymethacrylate (MMA) and side chains of polyether segments (PEO) of different chain lengths. It is found that the ionic conductivity can be increased to 10 -4 -10 -5 S / cm. MMA monomer acts as an internal plasticizer, increasing chain flexibility and free chain segment motion in the amorphous region of the polyether, increasing the distance between PEO chains and facilitating lithium ion migration. However, this improvement in ionic conductivity is achieved by lowering the polymer's glass transition temperature (Tg) and thus its crystallinity, which inevitably reduces the mechanical properties of the polymer electrolyte.

[0004] The existing problem of polymer electrolyte technology is that mechanical properties and ionic conductivity cannot be achieved at the same time. Even if some solid polymer electrolytes achieve ideal mechanical strength, their ionic conductivity is only 10 -5 S / cm. In order to improve the ionic conductivity, small molecule additives and electrolytes are usually added to polymer electrolytes. However, doing so will cause deformation and breakage of solid polymer electrolytes. Therefore, new technologies are needed to prepare electrolyte materials with both strong mechanical strength and high ionic conductivity. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems of low mechanical properties and ionic conductivity of polymer electrolytes in the prior art, and to provide a cross-linked polymer and a preparation method, an electrolyte composition, a polymer electrolyte and a preparation method, a lithium ion battery and an electrical device.

[0006] To achieve the above object, the present application provides a cross-linked polymer in a first aspect, wherein the cross-linked polymer comprises: macromolecular chains A from a compound a shown in formula (1), cross-linking structures B from a compound b shown in formula (2), and a connecting group -NH- connecting the macromolecular chains A and the cross-linking structures B;

[0007] The macromolecular chains A comprise polyether flexible chain segments.

[0008] The cross-linked polymer has a complex structure of hydrogen bonds and covalent bonds, wherein the covalent bond is -CN-, and the hydrogen bond is formed by complexing the hydrogen atom of the amino group in the compound b with the double bond oxygen atom on the nitrogen-containing heterocyclic ring in the compound a.

[0009]

[0010] R1 and R2 are each independently H, C1-C6 linear alkyl or C3-C6 branched alkyl; m is an integer of 1-100, and n is an integer of 1-100.

[0011] The present application provides a preparation method of a cross-linked polymer in a second aspect, wherein the preparation method comprises: performing a cross-linking reaction on a compound a shown in formula (1) and a compound b shown in formula (2) to obtain the cross-linked polymer; wherein the end group -OH in the compound a bonds with the end group -NH2 in the compound b to form a connecting group -NH-, and the hydrogen atom of the amino group in the compound b is complexed with the double bond oxygen atom on the nitrogen-containing heterocyclic ring in the compound a.

[0012]

[0013] R1 and R2 are each independently H, C1-C6 linear alkyl or C3-C6 branched alkyl; m is an integer of 1-100, and n is an integer of 1-100.

[0014] The present application provides a cross-linked polymer obtained by the preparation method in a third aspect.

[0015] The present application provides a polymer electrolyte raw material composition in a fourth aspect, wherein the composition comprises a lithium salt, a filler, a plasticizer and the cross-linked polymer.

[0016] The present application provides a preparation method of a polymer electrolyte in a fifth aspect, wherein the preparation method comprises:

[0017] (1) reacting the filler and the cross-linked polymer to form a film to obtain a film-forming material;

[0018] (2) mixing the film-forming material with a lithium salt solution and a plasticizer to obtain the polymer electrolyte.

[0019] The sixth aspect of the present application provides a polymer electrolyte prepared by the preparation method.

[0020] The seventh aspect of the present application provides a lithium ion battery, wherein the polymer lithium ion battery comprises the polymer electrolyte.

[0021] The eighth aspect of the present application provides a power consumption device comprising the lithium ion battery.

[0022] Through the above technical solution, the cross-linked polymer provided by the present application is different from the traditional polymer in that the cross-linked polymer structure is formed by the coexistence of hydrogen bonds and covalent bonds. The polymer is a cross-linked structure formed by covalent bonds and hydrogen bonds. The covalent bond is -C-N-, and the hydrogen bond is formed by the complexation of hydrogen atoms and oxygen atoms. The cross-linked polymer is characterized in that: the cross-linked structure is formed by covalent bonds and hydrogen bonds between chain segments. During the application of external force (in the lithium ion reaction process), the covalent bond does not break, and the hydrogen bond disappears. After the external force disappears, the covalent bond remains stable, and the hydrogen bond recovers. The existence of covalent bonds can improve and ensure the hardness and toughness of the polymer electrolyte, so that it can resist the lithium dendrite formed by the lithium metal negative electrode of the lithium ion battery, prevent the lithium dendrite from penetrating the polymer electrolyte to cause internal short circuit, and at the same time, the existence of reversible hydrogen bonds can provide the elasticity of the cross-linked polymer. The hydrogen bond dissipates external force without sacrificing the hardness and toughness provided by the covalent bond, preventing the cross-linked polymer from breaking. After the external force is removed, the hydrogen bond recovers, and the deformation recovers, which can resist the volume change of the positive and negative electrode materials of the lithium ion battery during the charging and discharging process. The structure of the cross-linked polymer is beneficial to improve the mechanical properties of the polymer electrolyte, overcome the low mechanical strength of the polymer electrolyte in the prior art, and provide a polymer electrolyte with high mechanical strength, high toughness, high elasticity, high ion conductivity, good thermal stability, high interface stability, simple preparation conditions, and easy industrialization. The present application provides a polymer electrolyte, a preparation method thereof, and a lithium ion battery comprising the polymer electrolyte. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the reaction product structure of pyrrolopyrrole diketone polyether and bithiophene vinyl triamine;

[0024] Figure 2 is a thermogravimetric analysis curve of the polymer electrolyte S1;

[0025] Figure 3 is a differential thermal analysis diagram of the polymer electrolyte S1 and polyethylene oxide;

[0026] Figure 4 is a stress-strain curve of the polymer electrolyte S1;

[0027] Figure 5 is a strain-time curve of the polymer electrolyte S1.

[0028] Figure 6 is a SEM image of the polymer electrolyte S1;

[0029] Figure 7 is a SEM image of the composite cathode C1;

[0030] Figure 8 is an electrochemical impedance spectrum of the polymer electrolyte S1;

[0031] Figure 9 is an ionic conductivity of the polymer electrolyte S1;

[0032] Figure 10 is a cyclic voltammogram of the polymer electrolyte S1. DETAILED DESCRIPTION

[0033] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as exactly that endpoint. Any values that fall within common

[0034] A cross-linked polymer is provided in a first aspect of the present application, wherein the cross-linked polymer comprises: a macromolecular chain A from a compound a shown in formula (1), a cross-linking structure B from a compound b shown in formula (2), and a connecting group -NH- connecting the macromolecular chain A and the cross-linking structure B;

[0035] wherein the macromolecular chain A comprises a polyether flexible chain segment;

[0036] The cross-linked polymer has a complex structure of hydrogen bond and covalent bond, wherein the covalent bond is -CN-, and the hydrogen bond is formed by the hydrogen atom of the amino group in the compound b and the double bond oxygen atom on the nitrogen-containing heterocyclic ring in the compound a;

[0037]

[0038] wherein R1, R2 are each independently H, C1-C6 linear alkyl or C3-C6 branched alkyl; m is an integer of 1-100, and n is an integer of 1-100.

[0039] In the present application, as Figure 1The hydroxyl group on the thienyl heterocycle in compound a is condensed with the amino group on the thienyl heterocycle in compound b to obtain a connecting group -NH-, wherein the macromolecular chain A is a part of compound a from which the hydroxyl group on the thienyl heterocycle is removed, the cross-linking structure B is a part of compound b from which the amino group on the thienyl heterocycle is removed, each compound b contains three amino groups which can react with the hydroxyl groups on the thienyl heterocycles in three compounds a respectively, each compound a has two hydroxyl groups, and the remaining hydroxyl group on the thienyl heterocycle in the cross-linked compound a can be condensed with the amino group on the thienyl heterocycle in another compound b, and so on, so as to form a large cross-linked polymer. The condensation to obtain the connecting group -NH- forms a covalent bond site, the N atom can form the covalent bond -CN- with the C atom on the thienyl heterocycle in compound a, the N atom can also form the covalent bond -CN- with the C atom on the thienyl heterocycle in compound b, and the hydrogen atom on the N atom can complex with the double-bonded oxygen atom on the pyrrolopyrrole heterocycle in the adjacent compound a segment to form a hydrogen bond, or the hydrogen atom on the N atom can complex with the double-bonded oxygen atom on the pyrrolopyrrole heterocycle in the non-adjacent compound a segment to form a hydrogen bond.

[0040] In the present application, the difference between the structure of the cross-linked polymer and that of the conventional polymer lies in that the hydrogen bond and the covalent bond coexist to form the cross-linked polymer which has a complex structure of hydrogen bond and covalent bond, wherein the covalent bond is -CN-, and the hydrogen bond is formed by the complexation of hydrogen atom and oxygen atom. The cross-linked polymer is characterized in that the cross-linking structure is formed by the covalent bond and the hydrogen bond between the segments, the covalent bond does not break and the hydrogen bond disappears during the application of external force (during the lithium ion reaction), the covalent bond remains stable and the hydrogen bond recovers after the external force disappears. The existence of the covalent bond can improve and ensure the hardness and toughness of the polymer electrolyte, so that it can resist the lithium dendrite formed by the lithium metal negative electrode of the lithium ion battery and prevent the lithium dendrite from penetrating the polymer electrolyte to cause internal short circuit; meanwhile, the existence of the reversible hydrogen bond can provide the elasticity of the cross-linked polymer, the hydrogen bond dissipates the external force without sacrificing the hardness and toughness provided by the covalent bond, so as to prevent the cross-linked polymer from breaking, and after the removal of the external force, the hydrogen bond recovers, and the deformation recovers, so as to resist the volume change of the positive and negative electrode materials of the lithium ion battery during the charging and discharging process.

[0041] In the present application, the cross-linked polymer has a complex structure of hydrogen bond and covalent bond, first, the hydrogen bond can dissipate under the action of applied pressure to respond to strain without breaking the covalent bond to cause permanent deformation of the material, after the disappearance of the applied pressure, the hydrogen bond is reformed and the shape of the material is restored, thus being beneficial to improve the mechanical properties of the polymer electrolyte; second, the hydrogen bond is independent of the glass transition temperature, and lowering the glass transition temperature of the polymer can improve the ionic conductivity without affecting the structure of the cross-linked polymer, thus not affecting the improvement of the mechanical properties of the cross-linked polymer, and the ionic conductivity can be kept at a high level while improving the mechanical properties of the polymer electrolyte.

[0042] In the present application, the cross-linked polymer contains ether oxygen functional groups capable of complexing lithium ions, which are polyether chain segments contained in formula (1), and the polyether can provide a high enough density of electron-donating groups and has a flexible polyether chain segment, wherein m and n are the repeating units of the flexible chain segment, m is 1-100, n is 1-100, preferably m is 3-60 and n is 3-60, thus the obtained cross-linked polymer is beneficial to improve the mechanical properties of the polymer electrolyte, and the polymer electrolyte has high mechanical strength, high toughness, high elasticity, high ionic conductivity, good thermal stability and high interfacial stability.

[0043] In some specific embodiments of the present application, the molar ratio of the macromolecular chain A to the cross-linked structure B in the polymer is 1-10:1, preferably 3-5:1.

[0044] In some specific embodiments of the present application, the weight average molecular weight of the polymer is 600,000-2,000,000 g / mol, which can make the room temperature ionic conductivity and transference number of lithium ions in the polymer electrolyte reach a high level.

[0045] The second aspect of the present application provides a preparation method of a cross-linked polymer, wherein the preparation method comprises: cross-linking reaction of a compound a represented by formula (1) and a compound b represented by formula (2) to obtain the cross-linked polymer; wherein the end group -OH in the compound a bonds with the end group -NH2 in the compound b to form a linking group -NH-; and the hydrogen atom of the amino group in the compound b complexes with the double bond oxygen atom on the nitrogen-containing heterocyclic ring in the compound a.

[0046]

[0047] wherein R1, R2 are each independently H, C1-C6 linear alkyl or C3-C6 branched alkyl; m is an integer of 1-100, and n is an integer of 1-100.

[0048] In some specific embodiments of the present application, the cross-linking reaction temperature is 100-150°C, preferably 120°C.

[0049] In some embodiments of the present application, the cross-linking reaction time is 10-20 min, preferably 15 min.

[0050] In some embodiments of the present application, the reaction is carried out in a solvent, which is chlorobenzene.

[0051] In some embodiments of the present application, the molar ratio of compound a: compound b is 1-10:1, preferably 3-5:1.

[0052] In some embodiments of the present application, the condensation reaction of the terminal group -OH in compound a with the terminal group -NH2 in compound b forms a linking group -NH-, which is formed by the condensation of the hydroxyl group on the thiophene heterocycle in compound a with the amino group on the thiophene heterocycle in compound b to form a covalent bond linkage; the hydrogen atom of the amino group in compound b is complexed with the double-bonded oxygen atom on the nitrogen-containing heterocycle in compound a to form a hydrogen bond linkage.

[0053] In the present application, the composition and structure of the cross-linked polymer can be determined by nuclear magnetic resonance, infrared, GPC, elemental analysis, etc., or by preparation of the feed.

[0054] The third aspect of the present application provides a cross-linked polymer prepared by the preparation method.

[0055] The fourth aspect of the present application provides a polymer electrolyte raw material composition, which comprises a lithium salt, a filler, a plasticizer, and the cross-linked polymer.

[0056] The polymer electrolyte provided by the present application contains, in addition to the cross-linked polymer and the lithium salt, other doping agents disclosed in the art to improve performance, such as SiO2 nanoparticles and small molecule liquid plasticizers, to reduce the content of crystalline regions in the polymer matrix and improve ionic conductivity.

[0057] In some embodiments of the present application, the lithium salt is selected from one or more of lithium bistrifluoromethylsulfonylimide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium tetraphenylborate, lithium chloride, lithium bromide, lithium chloroaluminate, lithium fluorocarbylsulfonate, LiCH3SO3, LiN(SO2CF3)2, LiN(SO2C2F5)2; preferably lithium bistrifluoromethylsulfonylimide.

[0058] In some embodiments of the present application, the filler is selected from one or more of TiO2, Al2O3, SiO2, MgO, ZrO2, LiNbO3, BaTiO3, PbTiO3, montmorillonite, and molecular sieves.

[0059] In some embodiments of the present application, the plasticizer is selected from one or more of ethylene carbonate, propylene carbonate, and vinylene carbonate.

[0060] In some embodiments of the present application, the cross-linked polymer is 25-50 parts by weight, the lithium salt is 20-40 parts by weight, the filler is 1-4 parts by weight, and the plasticizer is 20-40 parts by weight.

[0061] The ratio of the number of oxygen atoms in the cross-linked polymer to the number of lithium ions in the lithium salt in the polymer electrolyte provided by the present application is in the range of 6-40:1, and preferably 10:1 and 8:1 in order to maximize the ionic conductivity.

[0062] The fifth aspect of the present application provides a method for preparing a polymer electrolyte, wherein the method comprises:

[0063] (1) reacting the filler and the cross-linked polymer to form a film to obtain a film-forming material;

[0064] (2) mixing the film-forming material with a lithium salt solution and a plasticizer to obtain the polymer electrolyte.

[0065] In some embodiments of the present application, the method for preparing a polymer electrolyte comprises:

[0066] (1) reacting the cross-linked polymer and silicon dioxide to form a film to obtain a film-forming material;

[0067] (2) adding the film-forming material to a lithium salt solution, adsorbing and drying to form a film, adding propylene carbonate, swelling and forming a film to obtain the polymer electrolyte.

[0068] The sixth aspect of the present application provides a polymer electrolyte prepared by the method.

[0069] In some embodiments of the present application, the polymer electrolyte has an ionic conductivity of 0.48-5.5 S / cm, an electrochemical impedance of 470-540 Ω, an elongation at break of 115-129%, a tensile strength of 0.33-0.51 MPa, and a strain recovery rate of 63.4-82.3%. The polymer electrolyte has good elongation at break and tensile strength, and is therefore called an elastic polymer electrolyte. The cross-linked polymer is an elastic polymer matrix of the elastic polymer electrolyte.

[0070] In some embodiments of the present application, the polymer electrolyte has a thickness of 100-500 μm. The thickness of the polymer electrolyte is further optimized to achieve the best mechanical strength, avoid curling of the film during filling of the conductive material, and achieve high ionic conductivity. The ionic conductivity is preferably 400 μm.

[0071] The seventh aspect of the present application provides a lithium ion battery, wherein the polymer lithium ion battery comprises the polymer electrolyte. The lithium ion battery comprises a positive electrode, a negative electrode and the polymer electrolyte provided by the present application, and the polymer electrolyte is located between the positive electrode and the negative electrode.

[0072] The positive electrode comprises a positive electrode current collector and a positive electrode active material loaded thereon. The positive electrode current collector can be an aluminum foil. The present application does not have a special limitation on the positive electrode material. The positive electrode material generally comprises a positive electrode active material, a binder and a conductive agent. The positive electrode active material can be any of the commercially available positive electrode materials, such as LiFePO4, LiMnO2, LiNiO2, LiCoO2, LiVPO4F, LiFeO2 or a ternary system.

[0073] The negative electrode comprises a negative electrode current collector and a negative electrode active material loaded thereon. The negative electrode current collector can be a copper foil. The present application does not have a special limitation on the negative electrode material. The negative electrode material generally comprises a negative electrode active material, a binder and a conductive agent. The negative electrode active material can be any of the commercially available negative electrode materials, such as natural graphite, artificial graphite, hard carbon, soft carbon, lithium titanate or a mixture of one or more thereof.

[0074] The binder can be any of the binders known in the art, for example, one or more of polyvinylidene fluoride, polytetrafluoroethylene, styrene butadiene rubber and polyacrylate. The conductive agent can be any of the conductive agents known in the art, for example, one or more of graphite, carbon fiber, carbon black, metal powder, metal oxide and fiber.

[0075] The present application does not have a special limitation on the method for preparing the lithium ion battery comprising the polymer electrolyte. Any of the methods known in the art can be used, for example, a solution of the polymer electrolyte is coated on the surface of a positive electrode sheet and a negative electrode sheet, the polymer electrolyte is formed by drying to remove the solvent, then the positive electrode sheet and the negative electrode sheet coated with the polymer electrolyte are wound or stacked to prepare a pole core, which is placed in a battery shell, sealed, formed, sealed, packaged; or the polymer electrolyte is prepared first, then a film is attached to the surface of the positive electrode sheet or the negative electrode sheet, then the positive electrode sheet and the negative electrode sheet are wound or stacked to prepare a pole core, which is placed in a battery shell, sealed, formed, sealed, packaged; or the prepared polymer electrolyte is added between the positive electrode sheet and the negative electrode sheet attached with the polymer electrolyte provided by the present application, then the positive electrode sheet and the negative electrode sheet are wound or stacked to prepare a pole core, which is placed in a battery shell, sealed, formed, sealed, packaged. The added polymer comprises the polymer electrolyte provided by the present application, and also comprises other polymer electrolytes and separator materials. The sealing and formation are performed by using the methods known in the art.

[0076] The eighth aspect of the present application provides a power consuming device, wherein the lithium ion battery is included.

[0077] The present application will be described in detail below by way of examples.

[0078] The following examples and comparative examples are carried out under conventional conditions or under conditions recommended by the manufacturer, unless otherwise specified. The reagents or instruments used are conventional products available on the market, unless otherwise specified. The composition and structure of the crosslinked polymers described in the following examples and comparative examples can be determined by nuclear magnetic resonance, infrared, GPC, elemental analysis, etc., or by the preparation feedstock.

[0079] Example 1

[0080] (1) Preparation of crosslinked polymer

[0081] Compound a (wherein R1 = R2 = CH3, n = m = 3) and compound b are mixed in a molar ratio of 3:1, and the mixture is heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the weight average molecular weight of the crosslinked polymer is 800,000 g / mol.

[0082] At the same time, an appropriate amount of SiO2 with a particle size of 14 nm is added, heated to 150°C, stirred until uniform. The prepolymer melt is poured onto a glass sheet, heated to 150°C in a vacuum box overnight, and the resulting film is removed from the glass sheet, weighed, immersed in an ethyl acetate solution of lithium salt for 24 hours, and swelled. After swelling, the film is dried in a vacuum box at 60°C overnight, weighed to calculate the amount of lithium salt. The prepared polymer electrolyte film is immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate is added, the film is swelled for at least two hours and reaches equilibrium, and the final polymer electrolyte S1 is prepared.

[0083] (3) Preparation of polymer electrolyte composite electrode

[0084] An appropriate amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S1, and N-methyl pyrrolidone (NMP) are mixed uniformly, and the mixture is poured onto a block of polytetrafluoroethylene, vacuumed, heated to 150°C overnight to obtain the polymer electrolyte composite electrode C1.

[0085] Example 2

[0086] (1) Preparation of crosslinked polymer

[0087] Compound a (wherein R1= R2= CH3, n = m = 33) and compound b were mixed in a molar ratio of 3:1 and the mixture was heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the cross-linked polymer had a weight average molecular weight of 1.2 million g / mol.

[0088] (2) Preparation of polymer electrolyte

[0089] To the cross-linked polymer, an appropriate amount of SiO2 having a particle size of 14 nm was added, heated to 150°C, and stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum chamber overnight, and the resulting film was removed from the glass sheet, weighed, immersed in an ethyl acetate solution of lithium salt for 24 hours, and swelled. After swelling, the film was dried in a vacuum chamber at 60°C overnight, weighed, and the amount of lithium salt was calculated. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorption of moisture from the air. In the glove box, propylene carbonate was added, the film was swelled for at least two hours and reached equilibrium, and the final polymer electrolyte S2 was prepared.

[0090] (3) Preparation of polymer electrolyte composite electrode

[0091] An appropriate amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S2, and N-methyl pyrrolidone (NMP) were mixed uniformly, the mixture was poured onto a block of polytetrafluoroethylene, vacuumed, heated to 150°C overnight, and the polymer electrolyte composite electrode C2 was obtained.

[0092] Example 3

[0093] (1) Preparation of cross-linked polymer

[0094] Compound a (wherein R1= R2= CH3, n = m = 68) and compound b were mixed in a molar ratio of 3:1 and the mixture was heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the cross-linked polymer had a weight average molecular weight of 1.8 million g / mol.

[0095] (2) Preparation of polymer electrolyte

[0096] To the cross-linked polymer, an appropriate amount of SiO2with a particle size of 14 nm was added, heated to 150°C, and stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum box overnight, and the resulting film was removed from the glass sheet, weighed, and immersed in an ethyl acetate solution of lithium salt for 24 hours to swell. After swelling, the film was dried in a vacuum box at 60°C overnight, and the amount of lithium salt was calculated by weighing. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate was added, and the film was swelled for at least two hours and reached equilibrium to prepare the final polymer electrolyte S3.

[0097] (3) Preparation of a polymer electrolyte composite electrode

[0098] An appropriate amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S3, and N-methyl pyrrolidone (NMP) were mixed uniformly, and the mixture was poured onto a block of polytetrafluoroethylene, vacuumed, and heated to 150°C overnight to obtain a polymer electrolyte composite electrode C3.

[0099] Example 4

[0100] (1) Preparation of a cross-linked polymer

[0101] Compound a (wherein R1= R2= H, n = m = 3) and compound b were mixed in a molar ratio of 3:1, and the mixture was heated to 120°C in a chlorobenzene solvent to undergo polycondensation, wherein the weight average molecular weight of the cross-linked polymer was 600,000 g / mol.

[0102] (2) Preparation of a polymer electrolyte

[0103] To the cross-linked polymer, an appropriate amount of SiO2with a particle size of 14 nm was added, heated to 150°C, and stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum box overnight, and the resulting film was removed from the glass sheet, weighed, and immersed in an ethyl acetate solution of lithium salt for 24 hours to swell. After swelling, the film was dried in a vacuum box at 60°C overnight, and the amount of lithium salt was calculated by weighing. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate was added, and the film was swelled for at least two hours and reached equilibrium to prepare the final polymer electrolyte S4.

[0104] (3) Preparation of a polymer electrolyte composite electrode

[0105] A suitable amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S4, N-methyl pyrrolidone (NMP) were mixed uniformly, the mixture was poured onto a block of polytetrafluoroethylene, vacuum, heated to 150°C, overnight, to obtain a polymer electrolyte composite electrode C4.

[0106] Example 5

[0107] (1) Preparation of cross-linked polymer

[0108] Compound a (wherein R1= R2= H, n = m = 33) and compound b were mixed in a molar ratio of 3:1 and the mixture was heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the weight average molecular weight of the cross-linked polymer was 900,000 g / mol.

[0109] (2) Preparation of polymer electrolyte

[0110] A suitable amount of SiO2 with a particle size of 14 nm was added to the cross-linked polymer, heated to 150°C, stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum box, overnight, the generated film was removed from the glass sheet, weighed, soaked in a lithium salt ethyl acetate solution for 24 hours, swelled. After swelling, the film was dried in a vacuum box at 60°C overnight, weighed to calculate the amount of lithium salt. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate was added, the film swelled for at least two hours and reached equilibrium, and the final polymer electrolyte S5 was prepared.

[0111] (3) Preparation of polymer electrolyte composite electrode

[0112] A suitable amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S5, N-methyl pyrrolidone (NMP) were mixed uniformly, the mixture was poured onto a block of polytetrafluoroethylene, vacuum, heated to 150°C, overnight, to obtain a polymer electrolyte composite electrode C5.

[0113] Example 6

[0114] (1) Preparation of cross-linked polymer

[0115] Compound a (wherein R1= R2= H, n = m = 68) and compound b were mixed in a molar ratio of 3:1 and the mixture was heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the weight average molecular weight of the cross-linked polymer was 1,450,000 g / mol.

[0116] (2) Preparation of polymer electrolyte

[0117] To the cross-linked polymer, an appropriate amount of SiO2with a particle size of 14 nm was added, heated to 150°C, and stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum chamber overnight, and the resulting film was removed from the glass sheet, weighed, and immersed in an ethyl acetate solution of lithium salt for 24 hours to swell. After swelling, the film was dried in a vacuum chamber at 60°C overnight, and the amount of lithium salt was calculated by weighing. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate was added, and the film was swelled for at least two hours and reached equilibrium to prepare the final polymer electrolyte S6.

[0118] (3) Preparation of a polymer electrolyte composite electrode

[0119] An appropriate amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S6, and N-methyl pyrrolidone (NMP) were mixed uniformly, and the mixture was poured onto a block of polytetrafluoroethylene, vacuumed, and heated to 150°C overnight to obtain a polymer electrolyte composite electrode C6.

[0120] Example 7

[0121] (1) Preparation of a cross-linked polymer

[0122] Compound a (wherein R1= H, R2= CH3, n = m = 3) and compound b were mixed in a molar ratio of 3:1, and the mixture was heated to 120°C in a chlorobenzene solvent to undergo polycondensation, in which the weight average molecular weight of the cross-linked polymer was 700,000 g / mol.

[0123] (2) Preparation of a polymer electrolyte

[0124] To the cross-linked polymer, an appropriate amount of SiO2with a particle size of 14 nm was added, heated to 150°C, and stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum chamber overnight, and the resulting film was removed from the glass sheet, weighed, and immersed in an ethyl acetate solution of lithium salt for 24 hours to swell. After swelling, the film was dried in a vacuum chamber at 60°C overnight, and the amount of lithium salt was calculated by weighing. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate was added, and the film was swelled for at least two hours and reached equilibrium to prepare the final polymer electrolyte S7.

[0125] (3) Preparation of a polymer electrolyte composite electrode

[0126] A suitable amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S7, N-methyl pyrrolidone (NMP) were mixed uniformly, the mixture was poured onto a block of polytetrafluoroethylene, vacuum, heated to 150°C, overnight, to obtain a polymer electrolyte composite electrode C7.

[0127] Example 8

[0128] (1) Preparation of cross-linked polymer

[0129] Compound a (wherein R1=H, R2=CH3, n=m=33) and compound b were mixed in a molar ratio of 3:1 and the mixture was heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the weight average molecular weight of the cross-linked polymer was 1 million g / mol.

[0130] (2) Preparation of polymer electrolyte

[0131] A suitable amount of SiO2 with a particle size of 14 nm was added to the cross-linked polymer, heated to 150°C, stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum box, overnight, the generated film was removed from the glass sheet, weighed, soaked in a lithium salt ethyl acetate solution for 24 hours, swelled. After swelling, the film was dried in a vacuum box at 60°C overnight, weighed to calculate the amount of lithium salt. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate was added, the film swelled for at least two hours and reached equilibrium, and the final polymer electrolyte S8 was prepared.

[0132] (3) Preparation of polymer electrolyte composite electrode

[0133] A suitable amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S8, N-methyl pyrrolidone (NMP) were mixed uniformly, the mixture was poured onto a block of polytetrafluoroethylene, vacuum, heated to 150°C, overnight, to obtain a polymer electrolyte composite electrode C8.

[0134] Example 9

[0135] (1) Preparation of cross-linked polymer

[0136] Compound a (wherein R1=H, R2=CH3, n=m=68) and compound b were mixed in a molar ratio of 3:1 and the mixture was heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the weight average molecular weight of the cross-linked polymer was 1.6 million g / mol.

[0137] (2) Preparation of polymer electrolyte

[0138] Add an appropriate amount of SiO2 with a particle size of 14 nm to the cross-linked polymer, heat to 150°C, and stir until uniformly mixed. Pour the prepolymer melt onto a glass slide and heat to 150°C in a vacuum oven overnight. Remove the resulting film from the glass slide, weigh it, and soak it in an ethyl acetate solution of lithium salt for 24 hours to swell. After swelling, dry the film at 60°C in a vacuum oven overnight and weigh it to calculate the amount of lithium salt. The prepared polymer electrolyte film is immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate is added, and the film swells for at least two hours and reaches equilibrium to prepare the final polymer electrolyte S9.

[0139] (3) Preparation of polymer electrolyte composite electrodes

[0140] Take appropriate amounts of lithium iron phosphate (LiFePO4) (35wt%), single-walled carbon nanotubes (5wt%), the prepared polymer electrolyte S9, and N-methylpyrrolidone (NMP) and mix them evenly. Pour the mixture onto a block of polytetrafluoroethylene, vacuum, heat to 150°C, and leave overnight to obtain a polymer electrolyte composite electrode C9.

[0141] Example 10

[0142] (1) Preparation of cross-linked polymers

[0143] Compound a (wherein R1=H, R2=CH3, n=3, m=33) and compound b were mixed in a molar ratio of 3:1, and the mixture was heated to 120°C in a chlorobenzene solvent to cause condensation, wherein the weight average molecular weight of the cross-linked polymer was 1.1 million g / mol.

[0144] (2) Preparation of polymer electrolyte

[0145] An appropriate amount of SiO2 with a particle size of 14 nm was added to the cross-linked polymer, heated to 150°C, and stirred until uniformly mixed. The prepolymer melt was poured onto a glass slide and heated to 150°C in a vacuum oven overnight. The resulting film was removed from the glass slide, weighed, and immersed in an ethyl acetate solution of lithium salt for 24 hours to swell. After swelling, the film was dried in a vacuum oven at 60°C overnight and weighed to calculate the amount of lithium salt. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to prevent moisture absorption from the air. In the glove box, propylene carbonate was added, and the film was allowed to swell for at least two hours and reach equilibrium, thereby preparing the final polymer electrolyte S10.

[0146] (3) Preparation of polymer electrolyte composite electrodes

[0147] A suitable amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S10, N-methyl pyrrolidone (NMP) were mixed uniformly, the mixture was poured onto a block of polytetrafluoroethylene, vacuum, heated to 150°C, overnight, to obtain a polymer electrolyte composite electrode C10.

[0148] Example 11

[0149] (1) Preparation of cross-linked polymer

[0150] Compound a (wherein R1=H, R2=CH3, n=3, m=68) and compound b were mixed in a molar ratio of 3:1 and the mixture was heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the weight average molecular weight of the cross-linked polymer was 1.3 million g / mol.

[0151] (2) Preparation of polymer electrolyte

[0152] A suitable amount of SiO2 with a particle size of 14 nm was added to the cross-linked polymer, heated to 150°C, stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum box, overnight, the generated film was removed from the glass sheet, weighed, soaked in a lithium salt ethyl acetate solution for 24 hours, swelled. After swelling, the film was dried in a vacuum box at 60°C overnight, weighed to calculate the amount of lithium salt. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate was added, the film swelled for at least two hours and reached equilibrium, and the final polymer electrolyte S11 was prepared.

[0153] (3) Preparation of polymer electrolyte composite electrode

[0154] A suitable amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S11, N-methyl pyrrolidone (NMP) were mixed uniformly, the mixture was poured onto a block of polytetrafluoroethylene, vacuum, heated to 150°C, overnight, to obtain a polymer electrolyte composite electrode C11.

[0155] Example 12

[0156] (1) Preparation of cross-linked polymer

[0157] Compound a (wherein R1=H, R2=CH3, n=3, m=68) and compound b were mixed in a molar ratio of 3:1 and the mixture was heated to 120°C in chlorobenzene solvent to undergo polycondensation, wherein the weight average molecular weight of the cross-linked polymer was 1.3 million g / mol.

[0158] (2) Preparation of polymer electrolyte

[0159] To the cross-linked polymer, an appropriate amount of SiO2 with a particle size of 14 nm was added, heated to 150°C, and stirred until mixed uniformly. The prepolymer melt was poured onto a glass sheet, heated to 150°C in a vacuum box overnight, and the resulting film was removed from the glass sheet, weighed, immersed in an ethyl acetate solution of lithium salt for 24 hours, and swelled. After swelling, the film was dried in a vacuum box at 60°C overnight, weighed, and the amount of lithium salt was calculated. The prepared polymer electrolyte film was immediately transferred to an argon-filled glove box to avoid absorbing moisture from the air. In the glove box, propylene carbonate was added, the film was swelled for at least two hours and reached equilibrium, and the final polymer electrolyte S12 was prepared.

[0160] (3) Preparation of polymer electrolyte composite electrode

[0161] An appropriate amount of lithium iron phosphate (LiFePO4) (35 wt%), single-walled carbon nanotubes (5 wt%), the prepared polymer electrolyte S12, and N-methyl pyrrolidone (NMP) were mixed uniformly, the mixture was poured onto a block of polytetrafluoroethylene, vacuumed, heated to 150°C overnight, and the polymer electrolyte composite electrode C12 was obtained.

[0162] Comparative Example 1

[0163] 0.683 g of lithium salt (LiTFSI) and 1 g of polyethylene oxide (PEO) with a weight average molecular weight of 400000 g / mol were added to an appropriate amount of anhydrous acetonitrile, stirred at room temperature for 24 h, cast into a film in polytetrafluoroethylene, and vacuum dried at 50°C for 48 h to obtain a polymer electrolyte RS1, which is a polyethylene oxide electrolyte.

[0164] Test Example:

[0165] The cross-linked polymers prepared in Examples 1-12 were subjected to infrared spectroscopy analysis to determine that the prepared cross-linked polymers all contain macromolecular chains A, cross-linked structures B, connecting groups -NH-, covalent bonds -CN-, and hydrogen bonds, etc. The test instrument was Nicolet iS50 FT / IR spectrometer, and the instrument had a diamond attenuated total reflection accessory.

[0166] The polymer electrolytes S1-S12 prepared in Examples 1-12 and the RS1 of the comparative example were tested, and the results are shown in Table 1.

[0167] Thermogravimetric analysis: The instrument TAG-SDTA851 was used, the temperature rise rate was 20°C / min, and the temperature was raised to 600°C under nitrogen atmosphere. The test results of the polymer electrolyte S1 are shown in Table 2. Figure 2

[0168] ​Crystallinity and glass transition temperature: Differential scanning calorimeter (DSC-Q2000) was used, with indium standard calibration, sample weight was 8-10 mg, temperature range was -70℃ to 150℃, heating and cooling rate was 10℃ / min. The crystallinity and glass transition temperature of polymer electrolytes S1-S12 and RS1 were recorded, and the differential thermal analysis diagram of polymer electrolyte S1 was as shown in Figure 3 .

[0169] Tensile strength and elongation at break: Tensile and compression testing equipment Instron 5565 was used, and the strain rate of the instrument was 100% / min. The test results of polymer electrolyte S1 were as shown in Figure 4 and Figure 5 .

[0170] Morphology analysis of polymer electrolyte and composite electrode: Scanning electron microscope (FEI SL30 Sirion SEM) was used to characterize and analyze the morphology of polymer electrolyte S1 and composite electrode C1 of Example 1, as shown in Figure 6 and 7 . Lithium iron phosphate (LFP) particles were uniformly dispersed in the crosslinked polymer prepared in Example 1, and carbon nanotubes played a connecting role between the components, forming a conductive system, so that the composite electrode had good conductivity.

[0171] Electrochemical impedance test: The test frequency was 1 MHz to 100 mHz, the temperature was adjusted by a constant temperature and humidity chamber, the temperature change range was 20-80℃, and the perturbation signal was 50 mV. The electrochemical impedance spectrum of polymer electrolyte S1 was as shown in Figure 8 .

[0172] Conductivity: The polymer electrolytes S1-S12 prepared in Examples 1-12 and RS1 of the comparative example were cut into thin films with an area of 2 cm 2 and a thickness of 0.4 mm, and these polymer electrolyte films were sandwiched between two parallel stainless steel sheets in a glove to assemble a 2032 button cell, the cell model was “stainless steel sheet | polymer electrolyte film | stainless steel sheet”, a CHI660B type electrochemical workstation of Shanghai Chenhua Instrument Co., Ltd. was used, the test frequency range was 1-100 kHz, the temperature was -20℃, -15℃, 20℃, 50℃, 80℃, 110℃, and the bulk resistance (R h ) of the polymer electrolyte was the intersection of the Nyquist curve and the real axis, and the ionic conductivity was calculated according to the formula σ=I / (A·R h ), wherein σ was the ionic conductivity, I was the thickness of the polymer electrolyte film, and A was the contact area of the polymer electrolyte film and the electrode. The test and calculation results were as shown in Table 1 and Figure 9 .

[0173] Electrochemical stability test: the polymer electrolyte was assembled into a 2032 button cell in an argon-filled glove box, the cell model was "lithium metal sheet | polymer electrolyte film | stainless steel sheet", and the cyclic voltammetry method was used, the voltage scan was from open circuit voltage to-0.7V, and then rose to 5.5V, the rate was 1mV / s. The oxidation potential of the polymer electrolyte S1 was 4.3V (vs. Li), and the test results are shown in Figure 10 .

[0174] Table 1

[0175]

[0176]

[0177] From the results of Table 1, compared with the traditional electrolyte, the electrolyte prepared by using the cross-linked polymer provided by the application has better ion conductivity and lower electrochemical impedance, has excellent electrochemical performance, and the mechanical properties such as elongation at break, tensile strength and strain recovery rate are all better than those of the traditional electrolyte, which can effectively improve the safety performance of the lithium ion battery. The comprehensive performance of the polymer electrolyte of Example 10 is the best, which shows high ion conductivity and high tensile strength.

[0178] The preferred embodiments of the application are described in detail above, but the application is not limited thereto. Within the technical concept of the application, various simple modifications can be made to the technical solutions of the application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the application and belong to the protection scope of the application.

Claims

1. A cross-linked polymer, characterized in that The cross-linked polymer comprises: a macromolecular chain A derived from compound a represented by formula (1), a cross-linked structure B derived from compound b represented by formula (2), and a connecting group -NH- connecting the macromolecular chain A and the cross-linked structure B; Wherein, the macromolecular chain A includes a polyether flexible segment; The cross-linked polymer has a composite structure of hydrogen bonds and covalent bonds, wherein the covalent bond is -CN-, and the hydrogen bond is formed by the complexation of the hydrogen atom of the amino group in compound b and the double-bonded oxygen atom on the nitrogen-containing heterocyclic ring in compound a; （1）， （2）， Wherein, R1 and R2 are each independently H, C1-C6 straight-chain alkyl or C3-C6 branched-chain alkyl; m is an integer of 1-100, and n is an integer of 1-100.

2. The cross-linked polymer according to claim 1, characterized in that In the cross-linked polymer, the molar ratio of the macromolecular chain A to the cross-linked structure B is 1-10:

1.

3. The cross-linked polymer according to claim 1, wherein In the cross-linked polymer, the molar ratio of the macromolecular chain A: the cross-linked structure B is 3-5:1; And / or, in the cross-linked polymer, m is an integer of 3-60, and n is an integer of 3-60.

4. The cross-linked polymer according to any one of claims 1 to 3, characterized in that The weight average molecular weight of the cross-linked polymer is 600,000-2,000,000 g / mol.

5. A method for preparing a cross-linked polymer, characterized in that: The preparation method comprises: performing a cross-linking reaction on a compound a represented by formula (1) and a compound b represented by formula (2) to obtain the cross-linked polymer; wherein the terminal group -OH in the compound a is bonded with the terminal group -NH2 in the compound b to form a connecting group -NH-; the hydrogen atom of the amino group in the compound b is complexed with the double-bonded oxygen atom on the nitrogen-containing heterocyclic ring in the compound a; （1）， （2）， Wherein, R1 and R2 are each independently H, C1-C6 straight-chain alkyl or C3-C6 branched-chain alkyl; m is an integer of 1-100, and n is an integer of 1-100.

6. The preparation method according to claim 5, characterized in that The cross-linking reaction temperature is 100-150° C.; the cross-linking reaction time is 10-20 minutes.

7. The preparation method according to claim 5, wherein The cross-linking reaction is carried out in a solvent, and the solvent is chlorobenzene.

8. The preparation method according to any one of claims 5 to 7, characterized in that The molar ratio of compound a:compound b is 1-10:

1.

9. The preparation method according to claim 8, wherein The molar ratio of compound a:compound b is 3-5:

1.

10. A cross-linked polymer obtained by the preparation method according to any one of claims 5 to 9.

11. A polymer electrolyte raw material composition, characterized in that: include: A lithium salt, a filler, a plasticizer and the cross-linked polymer according to any one of claims 1 to 4 and 10.

12. The polymer electrolyte raw material composition according to claim 11, characterized in that The lithium salt is selected from one or more of lithium bis(trifluoromethylsulfonyl)imide, lithium hexafluorophosphate, lithium perchlorate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium hexafluorosilicate, lithium tetraphenylborate, lithium chloride, lithium bromide, lithium chloroaluminate, lithium fluoroalkylsulfonate, LiCH3SO3, LiN(SO2CF3)2, and LiN(SO2C2F5)2.

13. The polymer electrolyte raw material composition according to claim 12, wherein The lithium salt is selected from lithium bis(trifluoromethanesulfonyl)imide.

14. The polymer electrolyte raw material composition according to claim 11, wherein The filler is selected from one or more of TiO2, Al2O3, SiO2, MgO, ZrO2, LiNbO3, BaTiO3, PbTiO3, montmorillonite, and molecular sieve.

15. The polymer electrolyte raw material composition according to claim 11, wherein The plasticizer is selected from one or more of ethylene carbonate, propylene carbonate and vinylene carbonate.

16. The polymer electrolyte raw material composition according to any one of claims 11 to 15, characterized in that: The cross-linked polymer is 25-50 parts by weight, the lithium salt is 20-40 parts by weight, the filler is 1-4 parts by weight, and the plasticizer is 20-40 parts by weight.

17. A method for preparing a polymer electrolyte, characterized in that: The preparation method comprises: (1) reacting a filler with the cross-linked polymer according to any one of claims 1 to 4 and 10 to form a film to obtain a film-forming substance; (2) The film-forming substance is mixed with a lithium salt solution and a plasticizer to obtain the polymer electrolyte.

18. A polymer electrolyte obtained by the preparation method according to claim 17.

19. The polymer electrolyte according to claim 18, characterized in that The polymer electrolyte has an electrochemical impedance of 470-540Ω, an elongation at break of 115-129%, a tensile strength of 0.33-0.51 MPa, and a strain recovery rate of 63.4-82.3%.

20. A lithium ion battery, characterized in that: The polymer lithium-ion battery comprises the polymer electrolyte according to claim 18 or 19.

21. An electrical device, characterized in that: Including the lithium ion battery according to claim 20.

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