A single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS and its preparation method

Abstract

This invention discloses a POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane and its preparation method, relating to the field of polymer electrolytes. First, a sulfonylimide lithium salt monomer containing a methacrylamide structure is prepared. This monomer is then combined with a polymerizable POSS structure, EO segments, and a crosslinking agent, and a POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane is constructed via a two-step photoinitiated free radical polymerization. This invention solves the problem of significantly lower ionic conductivity of single-ion electrolytes compared to traditional dual-ion electrolytes, effectively improving ionic conductivity and lithium-ion transference number. The prepared electrolyte membrane exhibits a wide electrochemical window and good electrode-electrolyte compatibility, and lithium metal batteries assembled from it demonstrate excellent cycle performance.

Description

Technical Field

[0001] This invention relates to the field of polymer electrolytes, and more specifically to a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS and its preparation method. Background Technology

[0002] Against the backdrop of global energy restructuring to address environmental and energy crises, achieving efficient and secure energy storage is a crucial driving force for modern human societal development. Lithium metal possesses an extremely high theoretical specific capacity (3860 mAh g / g). -1 The low electrode potential (-3.04V relative to the standard hydrogen electrode) makes lithium metal batteries a promising next-generation high-energy-density energy storage device. However, traditional liquid electrolytes cause severe polarization on the electrode surface, leading to uneven lithium-ion deposition, the formation of needle-like lithium dendrites, which can then pierce the separator, causing electrolyte leakage and battery short circuits, resulting in safety issues. Therefore, developing solid electrolytes with good safety, chemical stability, and mechanical strength is crucial for the development of next-generation high-energy-density lithium metal batteries.

[0003] Traditional dual-ion polymer electrolytes contain free lithium salts. Because lithium ions more readily bind to Lewis bases, their mobility is significantly lower than that of anions, resulting in a lithium-ion transference number typically below 0.3. This leads to an anion concentration gradient, causing polarization, side reactions, and increased internal resistance, all of which endanger battery safety. In contrast, single-ion polymer electrolytes, with their anions fixed or bound, primarily utilize lithium ions for conduction. Due to their higher lithium-ion transference number, single-ion polymer electrolytes almost completely avoid concentration gradients and suppress lithium dendrite growth.

[0004] Since almost all the ions used for conduction in the electrolyte are lithium ions, the ionic conductivity of single-ion electrolytes is significantly lower than that of traditional dual-ion electrolytes. How to improve the room temperature ionic conductivity of single-ion polymer electrolytes is the most pressing problem to be solved. Summary of the Invention

[0005] Therefore, the purpose of this invention is to provide a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS and a method for preparing the same.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] <First Aspect>

[0008] This invention provides a single-ion conductor monomer, which is a sulfonylimide lithium salt monomer containing a methacrylamide structure, and the structural formula of the single-ion conductor monomer is as follows:

[0009]

[0010] <Second aspect>

[0011] This invention provides a method for preparing the above-mentioned single-ion conductor monomer, comprising the following steps:

[0012] Intermediate II and lithium hydroxide were dissolved in a third solvent, and methacrylamide chloride was added at a low temperature. After a complete reaction at 20–30°C, the product was extracted to obtain the single-ion conductor monomer. The structural formula of intermediate II is as follows: The low-temperature environment is -5 to 5℃.

[0013] As one implementation, the molar ratio of intermediate II, methacryloyl chloride, and lithium hydroxide is 1:(1-1.2):(1-1.2).

[0014] As one embodiment, the third solvent is one or more of acetone and acetonitrile.

[0015] As one implementation scheme, the preparation method of intermediate II is as follows: intermediate I, ferric chloride, and palladium on carbon catalyst are dissolved in a second solvent, hydrazine hydrate is added at 65-75°C, and the reaction is continued under reflux at 65-75°C. After the reaction is completed, the product is extracted to obtain intermediate II. The structural formula of intermediate I is:

[0016]

[0017] As one embodiment, the mass ratio of the three substances, intermediate I, ferric chloride and palladium on carbon, is 100:(3-10):(5-15).

[0018] In some embodiments, the mass ratio of intermediate I, ferric chloride, and palladium on carbon catalyst is 100:5:5.

[0019] In one embodiment, the mass ratio of intermediate I and hydrazine hydrate is 1:(1.2 to 1.5).

[0020] In one implementation scheme, the mass ratio of intermediate I and hydrazine hydrate is 2:3.

[0021] As one implementation, the second solvent is one or more of anhydrous ethanol and anhydrous methanol.

[0022] As one implementation method, the intermediate I is prepared by dissolving trifluoromethanesulfonamide, p-nitrobenzenesulfonyl chloride and a strong base in a first solvent, reacting them fully at a low temperature, and then extracting the product to obtain the intermediate I.

[0023] As one implementation, the molar ratio of trifluoromethanesulfonamide, p-nitrobenzenesulfonyl chloride, and the strong base is 1:(1-1.2):(2-2.2).

[0024] As one embodiment, the strong base is one or more of potassium hydroxide, sodium hydroxide, and lithium hydroxide.

[0025] As one implementation, the first solvent is one or more of acetone and acetonitrile.

[0026] In some embodiments, the strong base is potassium hydroxide, the first solvent is acetone, the second solvent is anhydrous ethanol, and the third solvent is acetone.

[0027] As one implementation scheme, in step S12, hydrazine hydrate is added to the reaction system by slow dropwise addition.

[0028] As one implementation scheme, in step S13, methacryloyl chloride is added to the reaction system by slow dropwise addition.

[0029] As one implementation, the slow dripping is achieved by controlling the dripping rate to 3-5 seconds per drop using a constant-pressure dripping funnel.

[0030] <Third aspect>

[0031] This invention provides the use of the above-mentioned single-ion conductor monomer.

[0032] The single-ion conductor monomer is used to prepare the electrolyte membrane for lithium-ion batteries.

[0033] <Fourth Aspect>

[0034] This invention provides a method for preparing a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS, comprising the following steps:

[0035] S21. Prepare precursor solution I containing poly(vinylidene fluoride-hexafluoropropylene) and prepare precursor solution II containing POSS material and crosslinking agent;

[0036] S22. After mixing the precursor liquid I and precursor liquid II, add the first part of the initiator, stir at 65-75°C to form a uniform solution, and then perform the first ultraviolet irradiation to initiate free radical polymerization.

[0037] S23. Add polyethylene glycol diacrylate, single-ion conductor monomer and second initiator to the solution after step S22, and stir at 65-75°C to obtain a uniform slurry.

[0038] S24. The slurry is coated onto a substrate to obtain a wet film, and the wet film is subjected to a second ultraviolet light irradiation to initiate free radical polymerization, and then dried to obtain an initial film;

[0039] S25. The initial membrane is immersed in an electrolyte to obtain a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS.

[0040] The single-ion conductor monomer has the following structural formula:

[0041]

[0042] As one implementation, the POSS material is a methacrylate-type polyhedral oligomeric silsesquioxane.

[0043] As one implementation, the POSS material is one or more of heptaisobutylmethacryloxypropyl oligosilsesquioxane, heptaisooctylmethacryloxypropyl oligosilsesquioxane, heptaphenylvinyl oligosilsesquioxane, and heptaphenylallyl oligosilsesquioxane.

[0044] In some embodiments, the POSS material is heptaisooctylmethacryloxypropyl oligomeric silsesquioxane.

[0045] As one embodiment, the crosslinking agent is one or more of pentaerythritol tetraacrylate, pentaerythritol triacrylate, trimethylolpropane triacrylate, and pentaerythritol tetra-3-mercaptopropionate.

[0046] In some embodiments, the crosslinking agent is pentaerythritol tetraacrylate.

[0047] As one embodiment, the first initiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin diethyl ether, and benzoin dimethyl ether.

[0048] As one embodiment, the second initiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin diethyl ether, and benzoin dimethyl ether.

[0049] In some embodiments, both the first initiator and the second initiator are 2-hydroxy-2-methyl-1-phenyl-1-propanone.

[0050] As one implementation scheme, the mass ratio of poly(vinylidene fluoride-hexafluoropropylene), POSS material, crosslinking agent, first initiator, polyethylene glycol diacrylate, single ion conductor monomer and second initiator is 10:(2.5~10):1.5:0.5:35:30:0.7.

[0051] In some embodiments, the mass ratio of poly(vinylidene fluoride-hexafluoropropylene), POSS material, crosslinking agent, first initiator, polyethylene glycol diacrylate, single ion conductor monomer and second initiator is 10:5:1.5:0.5:35:30:0.7.

[0052] As one embodiment, the solvent in the precursor solution I is one or more of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, acetone, and isopropanol.

[0053] In some embodiments, the solvent in the precursor solution I is N,N-dimethylformamide.

[0054] As one embodiment, the solvent in the precursor solution II is one or more of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, acetone, and isopropanol.

[0055] In some embodiments, the solvent in the precursor solution II is isopropanol.

[0056] As one implementation, the ultraviolet irradiation is irradiation under 365nm ultraviolet light for 10-15 minutes.

[0057] In some embodiments, the first ultraviolet irradiation is irradiation with 365nm ultraviolet light for 10 minutes.

[0058] In some embodiments, the second ultraviolet irradiation is irradiation with 365nm ultraviolet light for 10 minutes.

[0059] As one implementation, in step S24, the drying temperature is 65–75°C.

[0060] As one implementation, in step S25, the electrolyte is prepared according to V EC / V DEC = 1 / 1 electrolyte.

[0061] As one implementation, in step S25, the soaking time is 20 to 30 minutes.

[0062] In some embodiments, the soaking time in step S25 is 20 minutes.

[0063] <Fifth Aspect>

[0064] This invention provides a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS, which is prepared by the above-mentioned preparation method of the single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS.

[0065] As one embodiment, the POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane has a lithium-ion transference number of 0.78–0.85 and a lithium-ion mobility density of 3.9–5.93 × 10⁻⁶. -5 S cm -1 ionic conductivity at room temperature.

[0066] As one embodiment, the POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane has a lithium-ion transference number of 0.84–0.85 and a lithium-ion mobility density of 4.7–5.93 × 10⁻⁶. -5 S cm -1 ionic conductivity at room temperature.

[0067] In some embodiments, the POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane has a lithium-ion transference number of 0.85 and a lithium-ion migration factor of 5.93 × 10⁻⁶. -5 S cm -1 ionic conductivity at room temperature.

[0068] Compared with the prior art, the present invention has the following beneficial effects:

[0069] 1) This invention first provides a method for preparing a single-ion conductor monomer, which prepares a sulfonylimide lithium salt monomer containing a methacrylamide structure, and applies the prepared single-ion conductor monomer to the preparation of a POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane. The interpenetrating network structure is obtained by two-step photoinitiated free radical polymerization with polymerizable POSS structure, EO segments and crosslinking agent, which can effectively improve ionic conductivity and lithium ion transference number. Moreover, the electrolyte has a wide electrochemical window of 5.2V and good electrode-electrolyte compatibility. The lithium metal battery assembled from it has good cycle performance and can cycle 600 times at a current density of 1C.

[0070] 2) The electrolyte membrane provided by the present invention has the advantages of high safety, simple synthesis method, low production cost and large-scale production, and at the same time has high lithium ion transference number and ionic conductivity. Attached Figure Description

[0071] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0072] Figure 1 The 1H NMR spectrum of intermediate I prepared in Example 1 of this invention;

[0073] Figure 2 The 1H NMR spectrum of intermediate II prepared in Example 1 of this invention;

[0074] Figure 3The above is the proton nuclear magnetic resonance spectrum of the single-ion conductor monomer LiMATFSI prepared in Example 1 of this invention;

[0075] Figure 4 This is the AC impedance spectrum of the electrolyte membrane prepared in Example 4 of the present invention. Detailed Implementation

[0076] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0077] To facilitate understanding, the abbreviations or nouns mentioned below will be explained first:

[0078] POSS: Polyhedral oligomeric silsesquioxane;

[0079] MAPOSS: Methacrylate-type polyhedral oligomeric silsesquioxane. In this embodiment, heptaisooctylmethacryloyloxypropyl oligomeric silsesquioxane is selected, with the monomer structural formula as follows:

[0080]

[0081] LiMATFSI: (4-Methacrylamidobenzenesulfonyl)(trifluoromethanesulfonyl)imine lithium;

[0082] LiTFSI: Lithium bis(trifluoromethanesulfonyl)imide;

[0083] PVDF-HFP: Poly(vinylidene fluoride-hexafluoropropylene), with an average molecular weight of 400,000;

[0084] PEGDA: Polyethylene glycol diacrylate, with an average molecular weight of 1000;

[0085] PETEA: Pentaerythritol tetraacrylate;

[0086] HMPP: 2-Hydroxy-2-methyl-1-phenyl-1-propanone;

[0087] DMF: N,N-dimethylformamide.

[0088] First, a method for preparing a single-ion conductor monomer is introduced through Examples 1 to 3.

[0089] Example 1

[0090] A method for preparing a single-ion conductor monomer (LiMATFSI) includes the following steps:

[0091] S11. Dissolve 14.9 g (0.1 mol) trifluoromethanesulfonamide, 22.1 g (0.1 mol) 4-nitrobenzenesulfonyl chloride (also known as p-nitrobenzenesulfonyl chloride), and 11.2 g (0.2 mol) potassium hydroxide in acetone and react at 0 °C. After the reaction is complete, filter, rotary evaporate, wash, and dry the reaction solution to obtain a white solid powder, which is intermediate I. The 1H NMR spectrum is as follows. Figure 1 As shown; the structural formula is as follows:

[0092]

[0093] S12. Dissolve 37.2 g (0.1 mol) of intermediate I, ferric chloride, and palladium on carbon catalyst in anhydrous ethanol. Add hydrazine hydrate slowly dropwise at 70 °C. After the addition is complete, continue reflux at 70 °C. Once the reaction is complete, filter, rotary evaporate, wash, and dry the reaction solution to obtain a light yellow solid powder, which is intermediate II. The 1H NMR spectrum is shown below. Figure 2 As shown; the structural formula is as follows:

[0094]

[0095] S13. Dissolve 34.2 g (0.1 mol) of intermediate II and 2.4 g (0.1 mol) of lithium hydroxide in acetone, and slowly add 10.4 g (0.1 mol) of methacryloyl chloride at 0 °C. After the addition is complete, the reaction is carried out at room temperature. After the reaction is complete, the reaction solution is filtered, rotary evaporated, washed and dried to obtain a pale yellow solid powder, which is a single ion conductor monomer (LiMATFSI).

[0096] It should be noted that:

[0097] In steps S11, S12, and S13, the washing and drying process specifically involves washing the product three times with dichloromethane and then drying it at 70°C.

[0098] In step S11, an ice bath is used at 0°C for 24 hours to ensure a complete reaction.

[0099] In step S12, the amounts of ferric chloride and palladium on carbon catalyst are both 5 wt.% of the amount of intermediate I, and the amount of hydrazine hydrate is 150 wt.% of the amount of intermediate I;

[0100] In step S12, hydrazine hydrate is added slowly by controlling the dropping rate at 3-5 seconds per drop using a constant pressure dropping funnel.

[0101] In step S13, methacryloyl chloride is added slowly, with the dropping rate controlled at 3-5 seconds per drop using a constant-pressure dropping funnel.

[0102] In step S12, the reflux reaction time is 5 hours to ensure a complete reaction.

[0103] In step S13, an ice bath is used at 0°C for a reaction time of 24 hours to ensure a complete reaction.

[0104] In this embodiment, the amount of acetone or anhydrous ethanol used as a solvent should, in principle, be sufficient to dissolve all the reactants. In this example, the amount of acetone used in steps S11 and S13 is 100 ml, and the amount of anhydrous ethanol used in step S12 is 500 ml.

[0105] The proton NMR spectrum of LiMATFSI is as follows: Figure 3 As shown, the molecular structure of LiMATFSI is determined as follows:

[0106]

[0107] Example 2

[0108] A method for preparing a single-ion conductor monomer (LiMATFSI) is basically the same as that in Example 1 above, except that:

[0109] In step S11, the molar ratio of trifluoromethanesulfonamide, 4-nitrobenzenesulfonyl chloride, and potassium hydroxide is 1:1.2:2.

[0110] Example 3

[0111] A method for preparing a single-ion conductor monomer (LiMATFSI) is basically the same as that in Example 1 above, except that:

[0112] In step S13, the molar ratio of intermediate II, methacryloyl chloride, and lithium hydroxide is 1:1.2:1.2.

[0113] Next, the preparation method of the single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS will be introduced through Examples 4 to 6.

[0114] Example 4

[0115] A method for preparing a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS, the specific steps of which are as follows:

[0116] S21. Dissolve PVDF-HFP in solvent A to prepare precursor solution I. Dissolve POSS material and crosslinking agent in solvent B to prepare precursor solution II.

[0117] S22. After mixing precursor solution I and precursor solution II, add the first initiator and stir at 70°C to form a homogeneous solution. Then, irradiate with 365nm ultraviolet light for 10 minutes to initiate free radical polymerization.

[0118] S23. Add PEGDA, LiMATFSI and the second initiator to the solution obtained in step S22, and stir at 70°C to obtain a uniform slurry.

[0119] S24. The slurry obtained in step S23 is uniformly coated on a glass plate, irradiated with 365nm ultraviolet light for 10min to initiate free radical polymerization, and dried at 70℃ to obtain an initial POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane (hereinafter referred to as the initial membrane).

[0120] S25. Place the initial membrane obtained in step S24 in V. EC / V DEC Immerse in a 1 / 1 electrolyte solution for 20 minutes to obtain a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS.

[0121] It should be noted that:

[0122] In step S21, the POSS material is a methacrylate-type polyhedral oligomeric silsesquioxane (MAPOSS), such as one or more of heptaisobutylmethacryloyloxypropyl oligomeric silsesquioxane, heptaisooctylmethacryloyloxypropyl oligomeric silsesquioxane, heptaphenylvinyl oligomeric silsesquioxane, and heptaphenylallyl oligomeric silsesquioxane. In this embodiment, heptaisooctylmethacryloyloxypropyl oligomeric silsesquioxane is selected.

[0123] In step S21, the crosslinking agent is one or more of pentaerythritol tetraacrylate (PETEA), pentaerythritol triacrylate (PETA), trimethylolpropane triacrylate (TMPTA), and pentaerythritol tetra-3-mercaptopropionate. In this embodiment, PETEA is selected.

[0124] In steps S22 and S23, the initiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone (HMPP), benzoin diethyl ether, and benzoin dimethyl ether. In this embodiment, HMPP is used for both the first and second initiators.

[0125] The amounts of each substance used in each step, by mass, are as follows:

[0126] PVDF-HFP: 10 parts, MAPOSS: 5 parts, PETEA: 1.5 parts, first part HMPP: 0.5 parts, PEGDA: 35 parts, LiMATFSI: 30 parts, second part HMPP: 0.7 parts.

[0127] In step S21, solvent A is one or more of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, acetone, and isopropanol, and its amount is 5 to 10 times the mass of PVDF-HFP. In this embodiment, solvent A is DMF, and its amount is 6 times the mass of PVDF-HFP.

[0128] In step S21, solvent B is one or more of N,N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, acetone, and isopropanol, and the amount used is 5 to 10 times the mass of PVDF-HFP. In this embodiment, isopropanol is selected as solvent B, and the amount used is 6 times the mass of PVDF-HFP.

[0129] Example 5

[0130] A method for preparing a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS is basically the same as that in Example 4 above, except that:

[0131] In this embodiment, in step S21, the amount of MAPOSS is adjusted to 2.5 parts.

[0132] Example 6

[0133] A method for preparing a single-ion conductor interpenetrating network polymer electrolyte membrane containing POSS is basically the same as that in Example 4 above, except that:

[0134] In this embodiment, in step S21, the amount of MAPOSS is adjusted to 10 parts.

[0135] Comparative Example 1

[0136] A method for preparing a single-ion conductor interpenetrating network polymer electrolyte membrane without POSS is basically the same as the steps in Example 4 above, except that:

[0137] In step S21, the precursor liquid II does not contain POSS material; only the crosslinking agent is added to the second solvent to dissolve it and obtain the precursor liquid II.

[0138] In step S24, after slurry coating, free radical polymerization, and drying, the resulting initial membrane does not contain POSS and is used in step S25 to immerse it in the electrolyte to obtain a POSS-free single-ion conductor interpenetrating network polymer electrolyte membrane.

[0139] Comparative Example 2

[0140] A method for preparing a POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane by one-step photoinitiated polymerization, the steps of which are basically the same as those in Example 4 above, the difference being:

[0141] In step S22, the first initiator is not added, and photoinitiated free radical polymerization is not performed.

[0142] In step S24, after slurry coating, free radical polymerization, and drying, the initial membrane obtained contains POSS and is used in step S25 to obtain a POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane by immersion in electrolyte.

[0143] Comparative Example 3

[0144] A method for preparing a POSS-containing dual-ion conductor interpenetrating network polymer electrolyte membrane, the steps of which are basically the same as those in Example 4 above, with the difference being:

[0145] In S23, LiMATFSI is replaced with an equimolar amount of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0146] In step S24, after slurry coating, free radical polymerization, and drying, the resulting initial membrane contains POSS. This membrane is then used in step S25, where it is immersed in the electrolyte to obtain a POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane. Application performance testing:

[0147] The electrolyte membranes prepared in Examples 4 to 6 and Comparative Examples 1 to 3 were used to assemble CR2016 coin cells using a steel sheet|electrolyte|steel sheet method, respectively, in a frequency range of 1.0 × 10⁻⁶. 6 AC impedance was tested at Hz to 0.1Hz, 25℃ and 75℃, using the formula... Calculate the ionic conductivity, where σ is the ionic conductivity; L is the thickness of the electrolyte membrane, which is 180 μm; and S is the area of ​​the steel electrode, which is 2.06 cm². 2 R is the resistance of the electrolyte membrane.

[0148] The AC impedance spectrum of the electrolyte membrane prepared in Example 4 is as follows: Figure 4 As shown.

[0149] The electrolyte membranes prepared in Examples 4 to 6 and Comparative Examples 1 to 3 were used to assemble lithium-electrolyte-lithium-cell CR2032 coin cells. The current and AC impedance of the cells before and after polarization were measured at room temperature using the Bruce-Vincent-Evans method, according to the formula... Calculate the lithium-ion transference number, where t Li + It is the lithium-ion transference number, ΔV is the polarization voltage, I0 is the initial current, and I ss It is the steady-state current, R0 is the initial impedance, R ss It is the steady-state impedance.

[0150] The electrolyte membranes prepared in Examples 4 to 6 and Comparative Examples 1 to 3 were used to assemble lithium-electrolyte-steel CR2025 button cells, respectively. Linear scanning voltammetry was performed at room temperature with a starting voltage of 0V, a stopping voltage of 6V, and a scan rate of 0.01V / s.

[0151] The electrolyte membranes prepared in Examples 4 to 6 and Comparative Examples 1 to 3 were used to assemble Li / LiFePO4 batteries. Cyclic performance tests were conducted on a LAND CT2001A test system at 25°C, with the voltage range set to 2.5–4V and the current density to 1C.

[0152] The test results for each embodiment and comparative example are shown in Table 1.

[0153] Table 1 shows the ionic conductivity and lithium-ion transference number of the electrolyte membranes corresponding to Examples 4 to 6 and Comparative Examples 1 to 3.

[0154]

[0155] Clearly, compared to the comparative examples, the ionic conductivity and lithium-ion transference number of Examples 4 to 6 are improved to some extent.

[0156] In summary, in Examples 4 to 6 of this invention, the single-ion conductor polymer electrolyte exhibits a higher lithium-ion transference number compared to traditional dual-ion polymer electrolytes. Introducing the POSS structure into the single-ion interpenetrating network polymer electrolyte effectively promotes ion transport because the cage-like POSS molecules have a large volume, which disrupts the ordered arrangement of the polymer matrix and reduces its crystallinity. Furthermore, the POSS structure can further suppress anion movement, resulting in an even higher lithium-ion transference number.

[0157] Single-ion conductor polymer electrolytes, due to the immobilization of anions, can largely eliminate polarization, achieve uniform lithium-ion flux, and suppress lithium dendrite formation. POSS, as an organic-inorganic hybrid material, can directly participate in polymerization reactions and exhibits better compatibility compared to traditional inorganic particles. Introducing a POSS structure into polymer electrolytes not only improves the mechanical, electrochemical, and thermal properties of the polymer electrolyte but also promotes the formation of a stable electrode-electrolyte interface, which is beneficial for improving battery cycle stability.

[0158] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane, characterized in that, The method comprises the following steps: S21, configure precursor liquid I containing poly (vinylidene fluoride-hexafluoropropylene), and configure precursor liquid II containing POSS material and crosslinking agent; the POSS material is one of seven isobutyl methyl acryloxy propyl oligomeric silsesquioxane and seven isooctyl methyl acryloxy propyl oligomeric silsesquioxane, and the crosslinking agent is pentaerythritol tetraacrylate; S22, after mixing the precursor liquid I and the precursor liquid II, a first initiator is added, a uniform solution is formed after stirring at 65-75 DEG C, and then first ultraviolet light irradiation is performed to initiate free radical polymerization; the first initiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin diethyl ether and benzoin dimethyl ether; S23, polyethylene glycol diacrylate, single-ion conductor monomer and a second initiator are added to the solution after the step S22, the mixture is stirred at 65-75 DEG C to obtain a uniform slurry, and the second initiator is one or more of 2-hydroxy-2-methyl-1-phenyl-1-propanone, benzoin diethyl ether and benzoin dimethyl ether; S24, the slurry is coated on a substrate to obtain a wet film, the wet film is subjected to second ultraviolet light irradiation to initiate free radical polymerization, and then drying is performed to obtain an initial film; S25, the initial film is immersed in an electrolyte to obtain a single-ion conductor interpenetrating network polymer electrolyte film containing POSS; The monovalent ion conductor monomer has a structural formula as follows: .

2. The method of claim 1, wherein the method of making a POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane is characterized by, The mass ratio of poly (vinylidene fluoride-hexafluoropropylene), POSS material, crosslinking agent, first initiator, polyethylene glycol diacrylate, single-ion conductor monomer and second initiator is 10: (2.5-10) : 1.5: 0.5: 35: 30: 0.7; the solvent in the precursor liquid I or the solvent in the precursor liquid II is one or more of N, N-dimethylformamide, N-methylpyrrolidone, dimethyl sulfoxide, tetrahydrofuran, acetone and isopropyl alcohol.

3. The method of claim 1, wherein the method further comprises the step of: The ultraviolet light irradiation is 365 nm ultraviolet light irradiation for 10-15 min.

4. The method of claim 1, wherein the method further comprises the step of: The electrolyte is configured according to V EC / V DEC =1 / 1; the soaking treatment time is 20-30 min.

5. The method of claim 1, wherein the method is characterized by: The preparation method of the single-ion conductor monomer is that: intermediate II and lithium hydroxide are dissolved in a third solvent, methacryloyl chloride is added in a low temperature environment, then the product is obtained after sufficient reaction at 20-30 DEG C to obtain the single-ion conductor monomer, wherein the low temperature environment is-5-5 DEG C, the molar ratio of the intermediate II, methacryloyl chloride and lithium hydroxide is 1: (1-1.2) : (1-1.2), and the structural formula of the intermediate II is: 。 6. The method of claim 5, wherein the method further comprises the step of: The preparation method of the intermediate II is that: intermediate I, iron chloride and palladium-carbon catalyst are dissolved in a second solvent, hydrazine hydrate is added at 65-75 DEG C, and then reflux reaction is continuously performed at 65-75 DEG C, and the product is obtained after the reaction is completed to obtain the intermediate II, wherein the mass ratio of the intermediate I, iron chloride and palladium-carbon catalyst is 100: (3-10) : (5-15), the mass ratio of the intermediate I and hydrazine hydrate is 1: (1.2-1.5), and the structural formula of the intermediate I is: 。 7. The method of claim 6, wherein the method further comprises the step of: The preparation method of the intermediate I is that trifluoromethanesulfonamide, p-nitrobenzenesulfonyl chloride and a strong base are dissolved in a first solvent, and after sufficient reaction in a low temperature environment, the product is extracted to obtain the intermediate I, wherein the molar ratio of trifluoromethanesulfonamide, p-nitrobenzenesulfonyl chloride and the strong base is 1:(1-1.2):(2-2.2).

8. A POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane, characterized in that, is prepared according to the method of any one of claims 1 to 7, the POSS-containing single-ion conductor interpenetrating network polymer electrolyte membrane has a lithium ion transference number of 0.78 to 0.85 and a room temperature ionic conductivity of 3.9 to 5.93 x 10 -5 S cm -1 S cm.

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