Solid-state polymer electrolyte and preparation method and application thereof

Abstract

The present application relates to the technical field of solid-state batteries, and particularly relates to a solid-state polymer electrolyte and a preparation method and application thereof.The solid-state polymer electrolyte comprises a polymer metal organic framework PolyMOF, a polymer matrix and an alkali metal salt in a mass ratio of 0.01-0.2:0.5-1:0.5-1;wherein, the organic ligand of the polymer metal organic framework comprises an electron-deficient aromatic structure.The solid-state polymer electrolyte of the present application has high ionic conductivity, high Li + transference number and long-term cycle stability in a solid-state lithium metal battery, providing a new design idea for developing high-performance solid-state polymer electrolytes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid-state batteries, in particular to a solid-state polymer electrolyte and a preparation method and application thereof. BACKGROUND

[0002] Traditional liquid electrolytes are difficult to completely eliminate the risk of thermal runaway due to their inherent flammability, and their narrow electrochemical window (<4.3V) limits the application potential of high-voltage cathodes and lithium metal anodes. In contrast, polymer solid-state batteries, with their non-flammable solid-state electrolytes, eliminate the risk of combustion and explosion from the root, and can break through the energy density limit (theoretical specific energy >500 Wh / kg). It can be compatible with high-voltage cathodes (>5V) and high-capacity silicon-based / lithium metal anodes, thereby providing a solution that is both intrinsically safe and has a revolutionary energy performance for applications such as unmanned aerial vehicle ultra-long endurance flight, electric vehicle 1000 km range, deep sea and deep space extreme environment equipment, etc.

[0003] However, traditional polymer electrolytes have the key defects of low ionic conductivity and low Li + transference number at room temperature, which greatly restricts their practical application. Studies have shown that the Li + transference in polymer electrolytes is highly dependent on the local motion of polymer segments (such as bending and stretching, swinging). These segments form transient free volume holes through conformational changes, and then Li + transfers between adjacent holes through the "jumping mechanism". Therefore, by designing highly flexible segments (such as side chain modification, block copolymer [Nat. Mater. 2022, 21 (9), 1057-1065], cross-linked polymer [Angew. Chem. Int. Ed. 2024, 63, e202316087]) to hinder the regular arrangement of polymers and weaken the interchain forces (such as hydrogen bonds, crystalline regions), it is a common strategy to improve ionic conductivity. However, this method often damages the mechanical integrity of the material and increases the risk of lithium dendrite penetration. To improve Li + conductivity, researchers have explored the method of incorporating nano-fillers [Adv. Mater. 2025, 37 (10), 2419782], but the problem of uneven dispersion and aggregation of fillers is still a persistent challenge. High-concentration lithium salt formulations can improve ionic conductivity and interface stability, but at the cost of sacrificing mechanical strength [ACS Appl. Energy Mater. 2019, 2 (9), 6237-6245]. Similarly, single-ion conductor polymers designed to immobilize anions to suppress concentration polarization are also limited by the strong electronegativity of the immobilized anion group, which limits Li +effective dissociation, thus restricting the improvement of overall conductivity [Chem. Soc. Rev. 2017, 46 (3), 797-815]. So far, how to simultaneously realize efficient anion immobilization and fast Li + transport remains a key and unsolved scientific challenge. SUMMARY

[0004] To solve the above technical problems, the present application provides a solid-state polymer electrolyte and a preparation method and application thereof. The solid-state polymer electrolyte provided by the present application has high ionic conductivity, high Li + transference number and long-term cycle stability in solid-state lithium metal batteries at room temperature through anion-π + interaction. According to the present application, non-covalent interaction is extremely common in nature and chemical systems, and has great application value in the fields of life, materials, catalysis, supramolecular self-assembly, etc. Among them, anion-π interaction, which is the mutual attraction between anions and electron-deficient aromatic rings, shows a unique ability to stabilize anions. However, the moderate strength of conventional anion-π interaction often limits their application in electrolyte modulation. Therefore, developing enhanced electron-deficient π aromatic systems, especially by combining positively charged aromatic groups, provides a promising strategy for designing advanced solid-state polymer electrolytes.

[0005] In a first aspect, the present application provides a solid-state polymer electrolyte, comprising a polymer metal organic framework PolyMOF, a polymer matrix and an alkali metal salt in a mass ratio of 0.01-0.2:0.5-1:0.5-1; wherein the organic ligand of the polymer metal organic framework comprises an electron-deficient aromatic structure. In the solid-state polymer electrolyte provided by the present application, the organic ligand of the polymer metal organic framework is an electron-deficient aromatic structure, which can redistribute electrons through p-π conjugation effect, thereby establishing a delocalized π + aromatic structure that can effectively anchor anions (TFSI - , FSI - ) in the solid-state electrolyte and form anion-π + interaction with the anions. This force not only significantly improves the migration rate of Li + , but also induces the formation of a uniform and dense deposition layer of Li + at the electrode / electrolyte interface, making the solid-state battery exhibit excellent cycle stability. The present application regulates the behavior of anions in the polymer electrolyte through anion-π + interaction, providing a new design idea for developing high-performance solid-state polymer electrolytes.

[0006] As preferred, the mass ratio of the polymer metal organic framework PolyMOF, the polymer matrix, and the alkali metal salt is 0.05-0.15:1:1. The solid-state polymer electrolyte has better performance under the preferred ratio.

[0007] Preferably, the particle size of the polymer metal organic framework PolyMOF is 100-200 nm.

[0008] As preferred, the organic ligand comprises a first organic ligand; the first organic ligand is obtained by heating reaction of a polymer of tetrafluoroterephthalonitrile and spiro-bisindane in an acid solution; optionally, the organic ligand further comprises a second organic ligand, and the second organic ligand comprises terephthalic acid. The present application can further improve the comprehensive performance of the solid-state polymer electrolyte by optimizing the organic ligand.

[0009] Further preferably, the spiro-bisindane is 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spiro-bisindane; preferably, the molar ratio of the terephthalic acid and 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spiro-bisindane is 3-5:1, preferably 4:1. The effect is better under the preferred condition.

[0010] As preferred, the polymer matrix comprises polyvinylidene fluoride-hexafluoropropylene copolymer and / or polyethylene oxide; the molecular weight of the polyvinylidene fluoride-hexafluoropropylene copolymer is 400000-450000; the molecular weight of the polyethylene oxide is 100000-5000000.

[0011] Preferably, the alkali metal salt is a lithium salt, and the lithium salt comprises lithium trifluoromethanesulfonimide and / or lithium bisfluorosulfonimide.

[0012] In a second aspect, the present application provides a preparation method of the solid-state polymer electrolyte, comprising mixing, stirring, and then casting the powder of the polymer metal organic framework PolyMOF, the polymer matrix, the alkali metal salt, and the organic solvent.

[0013] As preferred, the preparation method of the solid-state polymer electrolyte further comprises:

[0014] 1) preparing an organic ligand of the polymer metal organic framework having an electron-deficient aromatic structure.

[0015] 2) synthesizing the polymer metal organic framework PolyMOF from the organic ligand of the polymer metal organic framework by a hydrothermal method.

[0016] 3) mixing, stirring, and then casting the polymer metal organic framework PolyMOF, the polymer matrix, the lithium salt, and the organic solvent.

[0017] As preferred, the mass ratio of the polymer metal organic framework PolyMOF, the polymer matrix and the lithium salt is 0.01-0.2:0.5-1:0.5-1, preferably 0.05-0.15:1:1.

[0018] Preferably, the volume ratio of the organic solvent to the total mass of the powder of the polymer metal organic framework PolyMOF, the polymer matrix and the lithium salt is 5-7 mL:2-3 g.

[0019] Preferably, the organic solvent is N,N'-dimethylformamide, N,N-dimethylacetamide or acetonitrile.

[0020] As preferred, the stirring temperature is 50-60℃ and the stirring time is 3-5 h.

[0021] Preferably, the casting forming condition is vacuum drying at 60-80℃.

[0022] Further preferably, the thickness of the solid-state polymer electrolyte membrane after forming is 100-200 μm.

[0023] As preferred, the organic ligand is a second organic ligand and / or a first organic ligand; the second organic ligand is terephthalic acid, and the first organic ligand is obtained by heating reaction of a polymer of tetrafluoroterephthalonitrile and helical bisindane in an acid solution; preferably, the helical bisindane is 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-helical bisindane; preferably, the molar ratio of the second organic ligand and the first organic ligand is 3-5:1, preferably 4:1.

[0024] Further preferably, in the preparation of the polymer metal organic framework PolyMOF, the molar ratio of the second organic ligand, the first organic ligand and zirconium tetrachloride is 3-5:1:0.3-0.4, preferably 4:1:0.35.

[0025] Further preferably, the preparation method of the first organic ligand comprises the following steps:

[0026] The tetrafluoroterephthalonitrile and 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-helical bisindane are subjected to polymerization reaction to obtain the polymer PIM-1.

[0027] Formula 1

[0028] The polymer PIM-1 is subjected to heating reaction in an acid solution to obtain the organic ligand PIM-COOH.

[0029] Formula 2

[0030] In a third aspect, the application provides application of the solid-state polymer electrolyte or the solid-state polymer electrolyte prepared by the preparation method in a lithium metal battery.

[0031] The application has at least the following beneficial effects: the application first embeds PolyMOF into a polymer system to obtain a PolyMOF-based solid-state electrolyte. The ligand in the PolyMOF-based solid-state electrolyte forms an electron-deficient π + system through p-π conjugation effect and electron rearrangement, which has a strong affinity for TFSI - , and is conducive to the formation of stable anion-π + interaction. The application effectively limits the free movement of TFSI - , promotes the uniform deposition of Li + , optimizes the SEI interface, and improves the cycle stability of the polymer solid-state battery. BRIEF DESCRIPTION OF DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0033] Figure 1 The structure diagram of the ligand of the PolyMOF in the embodiment of the application forming anion-π + interaction through p-π conjugation.

[0034] Figure 2 The SEM images of the PolyMOF and UMOF prepared in the embodiment of the application.

[0035] Figure 3 The SEM images of the surface and section of the PVHF, PolyMOF@PVHF and UMOF@PVHF electrolyte membranes in the embodiment of the application.

[0036] Figure 4 The infrared spectra of the PolyMOF and PolyMOF@LiTFSI in the embodiment of the application.

[0037] Figure 5 The infrared spectra of LiTFSI, PolyMOF@LiTFSI and UMOF@LiTFSI in the embodiment of the application.

[0038] Figure 6XPS spectra of LiTFSI, PolyMOF@LiTFSI and PolyMOF in C1s (a), O1s (b) and S2p (c) for the embodiments of the present application.

[0039] Figure 7 Ionic conductivity plots of PVHF (a), PolyMOF@PVHF (b) and UMOF@PVHF (c) for the embodiments of the present application.

[0040] Figure 8 Li+diffusion plots of PVHF (a), PolyMOF@PVHF (b) and UMOF@PVHF (c) for the embodiments of the present application. + Migration number plots.

[0041] Figure 9 3D TOF-SIMS plots of Li foil etched at different times after charge-discharge cycling of symmetric cells assembled with PVHF, PolyMOF@PVHF and UMOF@PVHF for the embodiments of the present application.

[0042] Figure 10 Plots of LFP / Li cells assembled for the embodiments of the present application at different rates.

[0043] Figure 11 Charge-discharge plots of NCM811 / Li cells assembled for the embodiments of the present application at different rates.

[0044] Figure 12 Long cycle performance plots of NCM811 / Li cells assembled for the embodiments of the present application at 1C. DETAILED DESCRIPTION

[0045] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0046] The endpoints of the ranges and any values disclosed in the present application are not limited to the precise values stated. The ranges or values should be construed to be approximations that allow for significant variation. Various embodiments of the ranges or values can be combined to form one or more new ranges or values, which are also within the scope of the present application.

[0047] Unless otherwise indicated, technical or conditions not specified in the embodiments of the present application are carried out according to the techniques or conditions described in the literature in the art, or according to the product instructions. The devices, instruments, reagents, etc. not specified by the manufacturer are all conventional products that can be purchased through regular channels. The experimental reagents and raw materials involved are commercially available, and the reagents are analytical grade products.

[0048] In some embodiments of the present application, the solid-state polymer electrolyte based on anion-π + The solid-state polymer electrolyte based on anion-π

[0049] 1) Add tetrafluoroterephthalonitrile, 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spirobisoindane and N,N'-dimethylformamide into a round-bottom flask, stir at 65°C under N2 until a clear solution is formed. Then slowly add potassium carbonate, and stir for 48-72h. After cooling, add the reaction mixture to deionized water, and filter the precipitate. Then dissolve the crude product in a good solvent, and precipitate from a poor solvent, filter, the good solvent being chloroform and / or tetrahydrofuran, and the poor solvent being methanol and / or acetone. Collect the precipitated product by vacuum filtration. Dry the product in an oven at 80-110°C overnight to obtain a yellow solid PIM-1, as shown in Formula 1, wherein n is 3-4.

[0050] Formula 1

[0051] 2) Add PIM-1 obtained in step 1) to a mixture of deionized water, acetic acid and concentrated sulfuric acid, and connect a condenser; preferably, the amount ratio of PIM-1, deionized water, acetic acid and concentrated sulfuric acid is 0.3-0.5 g: 15-20 mL: 5-8 mL: 15-20 mL; the mass concentration of the acetic acid is 99.5%±5%, and the mass concentration of the concentrated sulfuric acid is 98%±5%. Reflux at 120-150°C for 36-48h. After the reaction is completed, neutralize with deionized water, and filter the brown powder. To remove residual reagents, heat the powder in a slightly acidic deionized water solution containing deionized water and 3-4 drops of sulfuric acid under reflux for about 12-24h, filter, and dry at 100-130°C under vacuum overnight to obtain a brown solid PIM-COOH, as shown in Formula 2, wherein n is 3-4.

[0052] Formula 2

[0053] 3) Weigh the terephthalic acid, zirconium chloride, and PIM-COOH obtained in step 2); preferably, the molar ratio of the terephthalic acid, PIM-COOH, and zirconium tetrachloride is 4:1:0.35 (mmol), and then N, N'-dimethylformamide and anhydrous formic acid are added, and the reaction is carried out at 100-120°C for 36-48h in a polytetrafluoroethylene reactor. The obtained powder is washed with N, N'-dimethylformamide, methanol, and chloroform in turn, and then the precipitate is collected by centrifugation, dried in a vacuum oven at 100-120°C for 24-36h, and then N, N'-dimethylformamide and anhydrous formic acid are added, and the amount of the solvents such as N, N'-dimethylformamide and anhydrous formic acid can be set according to the conventional settings in the art, for example, the amount of N, N'-dimethylformamide is 4.5±0.5mL, and the amount of anhydrous formic acid is 0.375±0.025mL, and the reaction is carried out at 110±10°C for 36-48h in a polytetrafluoroethylene reactor. The obtained powder is washed with N, N'-dimethylformamide, methanol, and chloroform in turn, and then the precipitate is collected by centrifugation, dried in a vacuum oven at 110±10°C for 30±6h, to obtain PolyMOF powder.

[0054] 4) The PolyMOF powder obtained in step 3) is mixed with polyvinylidene hexafluoropropylene copolymer (PVHF) and lithium trifluoromethanesulfonimide (LiTFSI) in an N, N'-dimethylformamide solution, and stirred at 50-60°C for 3-5h; preferably, the molecular weight of the PVHF is 400000-450000, and the mass ratio of PolyMOF, PVHF, and LiTFSI is PolyMOF: PVHF: LiTFSI = 0.1-0.2g: 0.5-1g: 0.5-1g. Then the stirred solution is poured into a polytetrafluoroethylene mold, and dried in a vacuum oven at 60-80°C to remove the N, N'-dimethylformamide solution, to obtain a PolyMOF@PVHF solid-state electrolyte film.

[0055] 5) The PolyMOF@PVHF solid-state electrolyte film obtained in step 4) is cut into a 19mm disc, and a spacer / PolyMOF@PVHF / spacer cell is assembled in a glove box for ion conductivity testing. Preferably, the thickness of the PolyMOF@PVHF film is 100-200μm, the area size of the spacer is 2.0cm 2 , and the frequency range for ion conductivity testing is 0.1Hz-1MHz.

[0056] 6) Assemble Li / Li symmetric battery, LiFeP04(LFP) / Li and NCM811 / Li half battery with 19 mm electrolyte film obtained in step 5) in the glove box. Specifically, first put Li sheet or LFP or NCM811 cathode into the positive electrode battery shell, then put PolyMOF@PVHF solid electrolyte film, Li sheet, gasket, spring and negative electrode battery shell in turn, and finally use the battery pressing machine to package the battery to obtain the button solid-state battery. The LFP and NCM811 cathode are preferably obtained by slurry blade coating method. Specifically, 80% active material (LFP / NCM811), 10% carbon black, 10% polyvinylidene fluoride and 1-2 mL N-methyl pyrrolidone solution are ground until no obvious particles are present, and then a 100-200 pm blade is used to blade coat on an aluminum foil. The blade-coated cathode sheet is placed in a vacuum oven at 80-100°C for 12-24h.

[0057] 7) Test the Li + ion transference number of the Li / Li symmetric battery assembled in step 6). + The scan rate of the Li -1 ion transference number test is set to 0.01-0.1 mV s -2 .

[0058] 8) Test the cycle performance of the Li / Li symmetric battery assembled in step 6). Then disassemble the cycled battery and take out the Li sheet near the negative electrode side for 3D TOF-SIMS test. Among them, the Li sheet for 3D TOF-SIMS test is the Li sheet obtained by disassembling the battery after the symmetric battery is cycled at a current density of 0.1 mA cm - . - - -

[0059] 9) Test the rate performance of the LFP / Li and NCM811 / Li batteries assembled in step 6). Among them, the rate setting parameters of the LFP / Li and NCM811 / Li half batteries are 0.1-2 C.

[0060] Example 1

[0061] ​​​The present embodiment provides a kind of solid-state polymer electrolyte and its preparation method, as follows: in three neck flask 2 g tetrafluoroterephthalonitrile, 3.4g 5,5',6,6'-tetrahydroxy-3,3,3',3'-tetramethyl-1,1'-spiral double indane and 70mL N,N'-dimethylformamide are added, stirring under nitrogen atmosphere 65 DEG C until forming clear solution.Potassium carbonate 4.15g is then slowly added, and stirring reaction 72h.Cooling, the reaction mixture is added to 650mL water, and the precipitate is filtered.The crude PIM-1 is then dissolved in 160mL chloroform, and precipitated from 500mL methanol, and filtered.The product is then dissolved in 200mL tetrahydrofuran, and further precipitated in the mixture of acetone / tetrahydrofuran (600mL, 2:1 v / v).The precipitated product is collected by vacuum filtration.The product is dried in an oven at 110 DEG C overnight to obtain yellow PIM-1 solid powder.

[0062] 0.3g PIM-1, 18mL deionized water, 6mL acetic acid (99.5%) and 18mL concentrated sulfuric acid (98%) are sequentially added to a 100mL round bottom flask, and a condenser tube is connected.Stirring at 150 DEG C, 300rpm for 48h.After cooling, 500mL deionized water is added for neutralization, and the brown powder is filtered.In order to remove residual reagents, the powder is heated to reflux in a slightly acidic deionized water solution containing 200mL deionized water and 3-4 drops of sulfuric acid for about 12h, and dried at 130 DEG C under vacuum overnight after filtration to obtain PIM-COOH powder, as formula 2, wherein n is 3-4.

[0063] 0.28mmol terephthalic acid, 0.07mmol PIM-COOH, 0.35mmol zirconium chloride are weighed, 4mL N,N'-dimethylformamide and 0.39mL anhydrous formic acid are added, and the reaction is carried out in a polytetrafluoroethylene reactor at 120 DEG C for 48h.The obtained powder is sequentially washed with N,N'-dimethylformamide, methanol and chloroform twice, and then the precipitate is collected by centrifugation, and dried in a vacuum oven at 120 DEG C for 24h to obtain PolyMOF powder.

[0064] The PolyMOF powder is subjected to SEM test.

[0065] The PolyMOF powder is subjected to SEM test. -1 .

[0066] The solid-state electrolyte film was prepared by solution casting method. 0.05 g PolyMOF powder, 1 g PVHF (Mw ~ 400000), 1 g LiTFSI were dissolved in 7 mL N, N'-dimethylformamide solution, stirred at 60°C for 3 h. Then the stirred solution was poured into a polytetrafluoroethylene mold and dried in a vacuum oven at 60°C to remove the N, N'-dimethylformamide solution, obtaining a PolyMOF@PVHF solid-state electrolyte film.

[0067] The surface and cross-section of the obtained PolyMOF@PVHF solid-state electrolyte film were tested by SEM.

[0068] The PolyMOF@PVHF solid-state electrolyte film was cut into a 19 mm round piece, and the battery was assembled in the glove box according to the order of positive shell, gasket, PolyMOF@PVHF film, gasket, spring, negative shell, and the ion conductivity test was carried out, the test frequency range was 0.1 Hz-1 MHz. The thickness of the above-mentioned PolyMOF@PVHF film was 164 μm, and the area size of the gasket was 2.0 cm 2 .

[0069] The battery was assembled in the glove box according to the order of positive shell, Li sheet, PolyMOF@PVHF film, Li sheet, spring, negative shell, and the Li + migration number test was carried out, the test scan rate was 0.01 mV s -1 .

[0070] The battery was assembled in the glove box according to the order of positive shell, Li sheet, PolyMOF@PVHF film, Li sheet, spring, negative shell, and the symmetric battery cycle test was carried out. Then the cycled battery was disassembled, and the lithium sheet near the negative side was taken out for 3D TOF-SIMS test. The 3D TOF-SIMS test described above was obtained from the lithium sheet after the symmetric battery was cycled at a current density of 0.1 mA cm -2 for 50 cycles, and the 3D TOF-SIMS test elements included LiF2 - , LiO2H2 - , LiCO3 - and LiN - , etc.

[0071] The battery was assembled in the glove box according to the order of positive shell, LFP positive electrode, PolyMOF@PVHF film, Li sheet, spring, negative shell, and the different rate performance test of half battery was carried out. The different rates described above included 0.1, 0.2, 0.5, 1, 1.5, 2C.

[0072] The battery was assembled in the glove box in the order of positive shell, NCM811 positive electrode, PolyMOF@PVHF film, Li sheet, spring sheet, and negative shell, and the different rate performance test of the half battery was carried out. The different rates as mentioned above include 0.1, 0.2, 0.5, 1, 1.5, and 2C.

[0073] The battery was assembled in the glove box in the order of positive shell, NCM811 positive electrode, PolyMOF@PVHF film, Li sheet, spring sheet, and negative shell, and the long cycle performance test of the half battery at 1C was carried out.

[0074] Example 2

[0075] The steps of preparing PolyMOF in this example are the same as those in Example 1. The difference is that when preparing the solid-state electrolyte film, the lithium salt LiTFSI is replaced by the lithium bisfluorosulfonylimide salt (LiFSI). Specifically, the solution casting method is used to prepare the solid-state electrolyte film. 0.05 g of PolyMOF powder, 1 g of PVHF (Mw ~ 400000), and 1 g of LiFSI are dissolved in 7 mL of N,N'-dimethylformamide solution, and stirred at 60°C for 3 h. Then the stirred solution is poured into a polytetrafluoroethylene mold, and dried in a vacuum oven at 60°C to remove the N,N'-dimethylformamide solution, and obtain the PolyMOF@PVHF solid-state electrolyte film.

[0076] Example 3

[0077] The steps of preparing PolyMOF in this example are the same as those in Example 1. The difference is that when preparing the solid-state electrolyte film, the N,N'-dimethylformamide solution is replaced by the N,N'-dimethylacetamide solution. Specifically, the solution casting method is used to prepare the solid-state electrolyte film. 0.05 g of PolyMOF powder, 1 g of PVHF (Mw ~ 400000), and 1 g of LiTFSI are dissolved in 7 mL of N,N'-dimethylacetamide solution, and stirred at 60°C for 3 h. Then the stirred solution is poured into a polytetrafluoroethylene mold, and dried in a vacuum oven at 60°C to remove the N,N'-dimethylacetamide solution, and obtain the PolyMOF@PVHF solid-state electrolyte film.

[0078] Example 4

[0079] The preparation of PolyMOF in this example is the same as that in Example 1. The difference is that the N,N'-dimethylformamide solution is replaced by acetonitrile solution when preparing the solid-state electrolyte film. Specifically, the solid-state electrolyte film is prepared by the solution casting method. 0.05 g of PolyMOF powder, 1 g of PVHF (Mw ~ 400000), and 1 g of LiTFSI are dissolved in 7 mL of acetonitrile solution, and stirred at 60°C for 3 h. Then the stirred solution is poured into a polytetrafluoroethylene mold, and dried in a vacuum oven at 60°C to remove the acetonitrile solution, to obtain a PolyMOF@PVHF solid-state electrolyte film.

[0080] Example 5

[0081] The preparation of PolyMOF in this example is the same as that in Example 1. The difference is that the mass ratio of PolyMOF powder: PVHF: LiTFSI is 0.10:1:1. Specifically, 0.10 g of PolyMOF powder, 1 g of PVHF (Mw ~ 400000), and 1 g of LiTFSI are dissolved in 7 mL of N,N'-dimethylformamide solution, and stirred at 60°C for 3 h. Then the stirred solution is poured into a polytetrafluoroethylene mold, and dried in a vacuum oven at 60°C to remove the N,N'-dimethylformamide solution, to obtain a PolyMOF@PVHF solid-state electrolyte film.

[0082] Comparative Example 1

[0083] 0.35 mmol of terephthalic acid and 0.35 mmol of zirconium chloride are weighed, 4 mL of N,N'-dimethylformamide and 0.39 mL of anhydrous formic acid are added, and the mixture is reacted in a polytetrafluoroethylene reactor at 120°C for 48 h. The obtained powder is washed with N,N'-dimethylformamide, methanol, and chloroform in turn, twice each time, and then the precipitate is collected by centrifugation and dried in a vacuum oven at 120°C for 24 h, to obtain UMOF powder.

[0084] The UMOF powder is subjected to SEM testing.

[0085] The UMOF powder is subjected to infrared testing together with commercially available LiTFSI powder and a mixture of UMOF and LiTFSI, and the infrared testing range is 500-4000 cm -1 .

[0086] The solid-state electrolyte film was prepared by solution casting method. 0.05 g of UMOF powder, 1 g of PVHF (Mw ~ 400000), 1 g of LiTFSI were dissolved in 7 mL of N, N'-dimethylformamide solution, stirred at 60°C for 3h. Then the stirred solution was poured into a polytetrafluoroethylene mold and dried in a vacuum oven at 60°C to remove the N, N'-dimethylformamide solution, obtaining a UMOF@PVHF solid-state electrolyte film.

[0087] The surface and cross-section of the obtained UMOF@PVHF solid-state electrolyte film were tested by SEM.

[0088] The UMOF@PVHF solid-state electrolyte film was cut into a 19mm round piece, and the battery was assembled in the glove box according to the order of positive shell, gasket, UMOF@PVHF film, gasket, spring, negative shell, and the ion conductivity test was carried out, the test frequency range was 0.1hz-1MHz. The thickness of the above-mentioned UMOF@PVHF film was 136μm, and the area size of the gasket was 2.0cm 2 .

[0089] The battery was assembled in the glove box according to the order of positive shell, Li sheet, UMOF@PVHF film, Li sheet, spring, negative shell, and the Li + migration number test was carried out, the test scan rate was 0.01mV s -1 .

[0090] The battery was assembled in the glove box according to the order of positive shell, Li sheet, UMOF@PVHF film, Li sheet, spring, negative shell, and the cycle test of the symmetric battery was carried out. Then the cycled battery was disassembled, and the lithium sheet near the negative side was taken out for 3D TOF-SIMS test. The 3D TOF-SIMS test as described above was obtained from the lithium sheet after the symmetric battery was cycled at a current density of 0.1mA cm -2 for 50 cycles, and the 3D TOF-SIMS test elements included LiF2 - , LiO2H2 - , LiCO3 - and LiN - , etc.

[0091] The obtained UMOF@PVHF solid-state electrolyte film was cut into a 19mm round piece, and the battery was assembled in the glove box according to the order of positive shell, LFP positive electrode, UMOF@PVHF film, gasket, spring, negative shell, and the different rate performance test of the half battery was carried out. The different rates as described above included 0.1, 0.2, 0.5, 1, 1.5, 2C.

[0092] The battery was assembled in the glove box in the order of positive shell, NCM811 positive electrode, UMOF@PVHF film, gasket, spring, negative shell, and the different rate performance test of half battery was carried out. The different rates as mentioned above include 0.1, 0.2, 0.5, 1, 1.5, 2C.

[0093] Comparative Example 2

[0094] A solid-state electrolyte film was prepared by solution casting method. 1g PVHF (Mw 400000), 1g LiTFSI was dissolved in 7mL N,N'-dimethylformamide solution, stirred at 60°C for 3h. Then the stirred solution was poured into a polytetrafluoroethylene mold, and dried in a vacuum oven at 60°C to remove the N,N'-dimethylformamide solution, and obtain a PVHF solid-state electrolyte film.

[0095] The surface and cross-section of the obtained PVHF solid-state electrolyte film were respectively tested by SEM.

[0096] The PVHF solid-state electrolyte film was cut into a 19mm round piece, and the battery was assembled in the glove box in the order of positive shell, gasket, PVHF film, gasket, spring, negative shell, and the ion conductivity test was carried out, and the test frequency range was 0.1hz-1MHz. The thickness of the above-mentioned PVHF film was 119μm, and the area size of the gasket was 2.0cm 2 .

[0097] The battery was assembled in the glove box in the order of positive shell, Li sheet, PVHF film, Li sheet, spring, negative shell, and the Li + migration number test was carried out, and the test scan speed was 0.01mV s -1 .

[0098] The battery was assembled in the glove box in the order of positive shell, Li sheet, PVHF film, Li sheet, spring, negative shell, and the cycle test of symmetric battery was carried out. Then the cycled battery was disassembled, and the lithium sheet close to the negative side was taken out for 3D TOF-SIMS test. The 3D TOF-SIMS test as mentioned above is for the lithium sheet obtained after the symmetric battery is cycled at a current density of 0.1mA cm -2 for 50 cycles, and the 3D TOF-SIMS test elements include LiF2 - , LiO2H2 - , LiCO3 - and LiN - , etc.

[0099] The PVHF solid electrolyte membrane was cut into a 19 mm disc, and the battery was assembled in the glove box in the order of positive shell, LFP positive electrode, PVHF membrane, gasket, spring, and negative shell. The different rate performance test of half battery was carried out. The different rates as mentioned above include 0.1, 0.2, 0.5, 1, 1.5, and 2C.

[0100] The battery was assembled in the glove box in the order of positive shell, NCM811 positive electrode, PVHF membrane, gasket, spring, and negative shell. The different rate performance test of half battery was carried out. The different rates as mentioned above include 0.1, 0.2, 0.5, 1, 1.5, and 2C.

[0101] Test Example 1

[0102] The PolyMOF@PVHF solid electrolyte membrane, UMOF@PVHF solid electrolyte membrane, and PVHF solid electrolyte membrane prepared in Example 1 and Comparative Example 1-2 were respectively subjected to SEM morphology analysis, intermolecular force proof, and battery performance test. The ligand of PolyMOF forms anion-pi + interaction structure by p-pi conjugation Figure 1 . The test results are as follows:

[0103] Figure 2 is a SEM graph. As can be seen from the graph, the size of PolyMOF is 100-200 nm, and the particle size is uniform. The size of UMOF is 0.5-2 pm, and the particle size is not uniform.

[0104] Figure 3 is a SEM graph. As can be seen from the graph, the PolyMOF@PVHF solid electrolyte membrane is relatively dense on the surface and in the cross section, and there is no large hole. There are large holes on the surface and in the cross section of PVHF and UMOF@PVHF solid electrolyte membrane.

[0105] Figure 4 is an infrared spectrum. As can be seen from the graph, the C=O of PolyMOF is at 1665 cm -1 , and after the addition of LiTFSI, its C=O is red-shifted to 1662 cm -1 , indicating that a C=O … Li structure is formed. In addition, the C=C bond in PolyMOF moves from 1589 cm -1 to 1592 cm -1 , and the C-O-C bond moves from 1004 cm -1 to 1006 cm -1 , indicating that the oxygen atom forms a pi + electron-deficient aromatic system through p-pi conjugation effect, resulting in a blue shift of the peak position.

[0106] Figure 5 are the infrared spectra of LiTFSI, PolyMOF@LiTFSI and UMOF@LiTFSI. From the figure, it can be seen that after the interaction of LiTFSI and PolyMOF, the C-F, C-S-N, S-N-S peak positions of PolyMOF move obviously. It is proved that there is a strong anion-π + interaction between PolyMOF and LiTFSI.

[0107] Figure 6 are the XPS spectra of LiTFSI, PolyMOF@LiTFSI and PolyMOF in C1s (a), O1s (b) and S2p (c). From the figure, it can be seen that the oxygen atoms in the ligand of PolyMOF are re-distributed by p-π conjugation effect to form oxonium cation, resulting in the formation of electron-deficient π + system of aromatic ring, strong anion-π - interaction with TFSI + , which is consistent with the infrared conclusion.

[0108] Figure 7 are the ion conductivity diagrams of PVHF (a), PolyMOF@PVHF (b) and UMOF@PVHF (c). The ion conductivity of PolyMOF@PVHF at room temperature is 1.23×10 -3 S cm -1 , the ion conductivity of UMOF@PVHF at room temperature is 5.23×10 -4 S cm -1 , and the ion conductivity of PVHF at room temperature is 1.63×10 -4 S cm -1 .

[0109] Figure 8 are the Li + ion transference number diagrams of PVHF (a), PolyMOF@PVHF (b) and UMOF@PVHF (c). From the figure, it can be seen that the Li + ion transference number of PolyMOF@PVHF is the highest, which is 0.75. The Li + ion transference numbers of PVHF and UMOF@PVHF are 0.37 and 0.45, respectively.

[0110] Figure 9are 3D TOF-SIMS images of Li strips of Li / PVHF / Li, Li / PolyMOF@PVHF / Li and Li / UMOF@PVHF / Li symmetrical batteries etched at different times after charge-discharge cycles. As can be seen from the figure, there is a relatively thin SEI interface layer on the surface of the Li strip after the cycle of PolyMOF@PVHF, while there is a relatively thick SEI interface layer on the surface of the Li strip after the cycle of PVHF and UMOF@PVHF, indicating that the PolyMOF effectively limits the movement of TFSI + by anion-π - interaction, promotes the uniform deposition of Li + and optimizes the SEI interface.

[0111] Figure 10 are half-cell rate curve graphs of different solid-state electrolytes assembled with LFP as the positive electrode. As can be seen from the figure, the performance of the PolyMOF@PVHF electrolyte is best at different rates.

[0112] Figure 11 are half-cell rate curve graphs of different solid-state electrolytes assembled with NCM811 as the positive electrode. As can be seen from the figure, the performance of the PolyMOF@PVHF electrolyte is best at different rates.

[0113] Figure 12 is a long cycle curve graph of a half-cell assembled with PolyMOF@PVHF as the solid-state electrolyte and NCM811 as the positive electrode at 1C. As can be seen from the figure, the PolyMOF@PVHF solid-state electrolyte can still run stably after 200 cycles.

[0114] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, and not to limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A solid-state polymer electrolyte, characterized by, The polymer metal-organic framework (PolyMOF), a polymer matrix, and an alkali metal salt are present in a mass ratio of 0.01-0.2:0.5-1:0.5-1. The organic ligands of the polymer metal-organic framework include a first organic ligand and a second organic ligand. The first organic ligand is obtained by reacting tetrafluoroterephthalonitrile with a polymer of helical bisindenium in an acidic solution under heating. The second organic ligand includes terephthalic acid.

2. The solid polymer electrolyte according to claim 1, characterized in that, The mass ratio of the polymer metal-organic framework PolyMOF, the polymer matrix, and the alkali metal salt is 0.05-0.15:1:1; And / or, the particle size of the polymer metal-organic framework PolyMOF is 100-200 nm.

3. The solid polymer electrolyte according to claim 1 or 2, characterized in that, The polymer matrix comprises polyvinylidene fluoride-hexafluoropropylene copolymer and / or polyethylene oxide; the molecular weight of the polyvinylidene fluoride-hexafluoropropylene copolymer is 400,000-450,000; the molecular weight of the polyethylene oxide is 100,000-5,000,000. And / or, the alkali metal salt is a lithium salt, the lithium salt comprising lithium trifluoromethanesulfonylimide and / or lithium difluorosulfonylimide.

4. The method for preparing the solid polymer electrolyte according to any one of claims 1-3, characterized in that, The process involves mixing and stirring the polymer metal-organic framework (PolyMOF) powder, polymer matrix, alkali metal salt, and organic solvent, followed by casting.

5. The preparation method according to claim 4, characterized in that, Also includes: 1) Prepare organic ligands for the polymer metal-organic framework; 2) The organic ligands of the polymer metal-organic framework are synthesized into PolyMOF by a hydrothermal method; 3) Mix and stir the polymer metal-organic framework PolyMOF, polymer matrix, lithium salt and organic solvent, and then cast it into shape.

6. The preparation method according to claim 5, characterized in that, The mass ratio of the polymer metal-organic framework PolyMOF, the polymer matrix, and the lithium salt is 0.01-0.2:0.5-1:0.5-1; And / or, the volume ratio of the organic solvent to the total mass of the polymer metal-organic framework (PolyMOF) powder, polymer matrix, and lithium salt is 5-7 mL: 2-3 g; And / or, the organic solvent is N,N'-dimethylformamide, N,N-dimethylacetamide, or acetonitrile.

7. The preparation method according to claim 5, characterized in that, The stirring temperature is 50-60℃, and the stirring time is 3-5 hours; And / or, the casting conditions are vacuum drying at 60-80 ℃.

8. The preparation method according to any one of claims 4-7, characterized in that, The thickness of the solid polymer electrolyte membrane after molding is 100-200μm.

9. The application of the solid polymer electrolyte according to any one of claims 1-3 or the solid polymer electrolyte obtained by the preparation method according to any one of claims 4-8 in lithium metal batteries.

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