Preparation Method and Application of a Single-Ion Polymer Solid Electrolyte

Abstract

A preparation method and application of a single-ion polymer solid electrolyte, which relates to a preparation method of a solid electrolyte. The purpose of the present invention is to solve the problems of too low lithium ion transference number and poor cycle stability of the existing polymer solid electrolyte. The present invention uses a lithium salt containing a hydroxyl group to prepare a polymer electrolyte with a polymer containing a halogen through a Williamson reaction, grafts the lithium salt containing a hydroxyl group onto the copolymer containing a halogen, and obtains a single-ion polymer solid electrolyte with positive electrode stability. A single-ion polymer solid electrolyte is used to assemble a lithium metal battery. The single-ion polymer solid electrolyte provided by the present invention has a high lithium ion transference number, good discharge specific capacity and high capacity retention rate, which is attributed to the chemical structure of the polymer electrolyte; the lithium metal battery assembled with the single-ion polymer solid electrolyte prepared by the present invention has excellent battery performance and good commercial promotion prospects.

Description

Technical Field

[0001] The present invention relates to a method for preparing a solid electrolyte. Background Art

[0002] In view of the global climate crisis and the shortage of fossil fuels, traditional fossil fuel vehicles are at risk of being phased out, and new energy electric vehicles have thus developed rapidly. In order to achieve the new capacity target of 500 W·h·kg -1 set for electric vehicle applications and achieve a longer driving range, it is necessary to replace the commonly used flammable liquid electrolyte (such as LiPF 6 solution in organic carbonates) with a solid electrolyte with higher safety to inhibit dendritic lithium deposition that can cause short circuits and thermal runaway of the battery.

[0003] Among various solid electrolyte technologies, polymer electrolytes have attracted much attention due to their advantages such as small volume change during charge / discharge, high safety, and easy manufacturing. Commercial polymer electrolytes complexed with lithium salts are dual-ion conductors, where both lithium ions and anions are mobile ions. Generally, the movement speed of anions is at least four times that of lithium ions because the movement of cations is highly coupled with the Lewis basic sites in the polymer host. Therefore, the transfer of lithium ions only accounts for a small part (20%) of the total ionic current. In addition, since anions do not have electrode reactions, anions will accumulate at the interface between the electrode and the electrolyte, resulting in battery polarization and limited cycle life.

[0004] To address the problems caused by the low lithium ion transference number of polymer electrolytes, developing a single-ion polymer electrolyte with a higher lithium ion transference number is an urgent problem to be solved in the art. To solve the above problems, by covalently fixing anion fragments on the polymer backbone, the electrodeposition process on the lithium anode can be made more stable, avoiding battery polarization caused by the concentration difference between cation and anion transport, thereby achieving single-ion transport in solid polymer electrolytes. In this single-ion polymer electrolyte (SIPE), theoretically only Li + ions are mobile, the Li + ion transference number (t Li+ ) is close to 1, and the anion transference number is close to 0, which is beneficial to achieving higher energy and power densities. Therefore, adopting SIPE can improve the safety of the battery, achieve the high-capacity target of the battery, and ensure the cycle life of the battery. Summary of the Invention

[0005] The object of the present invention is to solve the problems of too low lithium ion transference number and poor cycle stability of existing polymer solid electrolytes, and to provide a method for preparing a single-ion polymer solid electrolyte.

[0006] The present invention uses a lithium salt containing a hydroxyl group to prepare a polymer electrolyte by Williamson reaction with a halogen-containing polymer, grafting the lithium salt containing a hydroxyl group onto the halogen-containing copolymer to obtain a single-ion polymer solid electrolyte with positive electrode stability.

[0007] A preparation method of a single-ion polymer solid electrolyte is specifically completed according to the following steps:

[0008] I. Preparation of lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide:

[0009] Dissolve lithium hydroxide monohydrate in acetonitrile to obtain an acetonitrile solution of lithium hydroxide monohydrate; add 3-chloropropanesulfonyl chloride and trifluoromethanesulfonamide to the acetonitrile solution of lithium hydroxide monohydrate, cool it to room temperature in an ice-water bath, and then stir and react at room temperature for a period of time. After the reaction is completed, filter the mixture to remove solid substances to obtain a filtrate; concentrate the filtrate using a rotary evaporator to obtain a solid product; dissolve the solid product in dichloromethane, filter off the precipitated salt, and then concentrate the filtrate using a rotary evaporator and dry it under vacuum to obtain a white solid, which is lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide;

[0010] II. Preparation of lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide:

[0011] Add lithium hydroxide monohydrate to water, and then add lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide to obtain a mixed solution; stir and react the mixed solution at 105°C to 110°C for a period of time. After the reaction is completed, filter the mixture to remove solid substances to obtain a filtrate; concentrate the filtrate using a rotary evaporator to obtain a solid product; add acetonitrile to the solid product, and then stir at room temperature for a period of time, filter, collect and concentrate the supernatant, and finally dry it under vacuum to obtain lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide;

[0012] III. Preparation of a single-ion polymer solid electrolyte:

[0013] Under a nitrogen atmosphere, uniformly mix lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide, anhydrous N,N-dimethylformamide, and lithium hydride to obtain a mixed solution; add PVDF-CTFE to the mixed solution, and then stir and react at 45°C to 50°C for a period of time. After the reaction is completed, filter the mixture to remove solid substances to obtain a filtrate; pour water into the filtrate for phase inversion to obtain a reaction product; wash the reaction product with acetonitrile and then dry it under vacuum to obtain a single-ion polymer solid electrolyte.

[0014] A single-ion polymer solid electrolyte is used for assembling a lithium-ion battery.

[0015] Advantages of the present invention:

[0016] The single-ion polymer solid electrolyte provided by the present invention has a high lithium ion transference number, good discharge specific capacity and high capacity retention rate, which is attributed to the chemical structure of the polymer electrolyte; the lithium salt fragment is fixed on the polymer chain, and the anion does not move, resulting in a polymer electrolyte with a high lithium ion transference number; the lithium bis(sulfonyl)imide in the single-ion polymer has a special structure, in which the electron delocalization of the nitrogen atom is strong, making Li + more likely to dissociate from the lithium salt chain to provide a lithium source, and the obtained polymer electrolyte has good electrochemical performance; in summary, the lithium metal battery assembled with the single-ion polymer solid electrolyte prepared by the present invention has excellent battery performance and good commercial promotion prospects. Description of the Drawings

[0017] Figure 1 are the 1H NMR spectra of 3-chloropropanesulfonyl chloride, LICPSI prepared in Step 1 of Example 1, and LIHPSI prepared in Step 2 of Example 1;

[0018] Figure 2 are the infrared spectra of PVDF-CTFE, LIHPSI prepared in Step 2 of Example 1, and PVDF-CTFE-LIHPSI prepared in Step 3 of Example 1;

[0019] Figure 3 is the ionic conductivity graph of the SS||SS (stainless steel) battery assembled with PVDF-CTFE-LIHPSI prepared in Step 3 of Example 1;

[0020] Figure 4 is the electrochemical stability window graph of the Li||SS (stainless steel) battery assembled with PVDF-CTFE-LIHPSI prepared in Step 3 of Example 1;

[0021] Figure 5 are the chronoamperometry (CA) of PVDF-CTFE-LIHPSI prepared in Step 3 of Example 1 and the EIS spectra recorded before and after the CA test;

[0022] Figure 6 is the rate performance of the Li||PCL||LFP battery assembled with PVDF-CTFE-LIHPSI prepared in Step 3 of Example 1;

[0023] Figure 7 is the cycling performance of the Li||PCL||LFP battery assembled with PVDF-CTFE-LIHPSI prepared in Step 3 of Example 1. Detailed Embodiments

[0024] Embodiment 1: A preparation method of a single-ion polymer solid electrolyte is specifically completed according to the following steps:

[0025] I. Preparation of lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide:

[0026] Dissolve lithium hydroxide monohydrate in acetonitrile to obtain an acetonitrile solution of lithium hydroxide monohydrate; add 3-chloropropanesulfonyl chloride and trifluoromethanesulfonamide to the acetonitrile solution of lithium hydroxide monohydrate, cool it to room temperature in an ice-water bath, and then stir and react at room temperature for a period of time. After the reaction is completed, filter the mixture to remove solid substances to obtain a filtrate; concentrate the filtrate using a rotary evaporator to obtain a solid product; dissolve the solid product in dichloromethane, filter off the precipitated salt, and then concentrate the filtrate using a rotary evaporator and vacuum-dry it to obtain a white solid, which is lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide;

[0027] II. Preparation of lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide:

[0028] Add lithium hydroxide monohydrate to water, and then add lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide to obtain a mixed solution; stir and react the mixed solution at 105 °C to 110 °C for a period of time. After the reaction is completed, filter the mixture to remove solid substances to obtain a filtrate; concentrate the filtrate using a rotary evaporator to obtain a solid product; add acetonitrile to the solid product, and then stir at room temperature for a period of time, filter, collect and concentrate the supernatant, and finally vacuum-dry it to obtain lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide;

[0029] III. Preparation of the single-ion polymer solid electrolyte:

[0030] Under a nitrogen atmosphere, uniformly mix lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide, anhydrous N,N-dimethylformamide, and lithium hydride to obtain a mixed solution; add PVDF-CTFE to the mixed solution, and then stir and react at 45 °C to 50 °C for a period of time. After the reaction is completed, filter the mixture to remove solid substances to obtain a filtrate; pour water into the filtrate for phase inversion to obtain a reaction product; wash the reaction product with acetonitrile and then vacuum-dry it to obtain the single-ion polymer solid electrolyte.

[0031] Embodiment 2: The difference between this embodiment and Embodiment 1 is that in step I, the molar ratio of lithium hydroxide monohydrate to the volume of acetonitrile is (150 mmol to 250 mmol):70 mL; in step I, the molar ratio of 3-chloropropanesulfonyl chloride to the volume of acetonitrile is (80 mmol to 120 mmol):70 mL. Other steps are the same as those in Embodiment 1.

[0032] Specific Embodiment 3: The difference between this embodiment and one of Specific Embodiments 1 or 2 is as follows: In Step 1, the molar ratio of the amount of trifluoromethanesulfonamide to the volume of acetonitrile is (80 mmol - 120 mmol):70 mL; in Step 1, the stirring reaction time at room temperature is 18 h - 20 h. Other steps are the same as those in Specific Embodiment 1 or 2.

[0033] Specific Embodiment 4: The difference between this embodiment and one of Specific Embodiments 1 to 3 is as follows: In Step 1, the volume ratio of dichloromethane to acetonitrile is (30 mL - 40 mL):70 mL; in Step 1, the temperature of vacuum drying is 40°C - 50°C, and the vacuum drying time is 12 h - 18 h. Other steps are the same as those in Specific Embodiments 1 to 3.

[0034] Specific Embodiment 5: The difference between this embodiment and one of Specific Embodiments 1 to 4 is as follows: In Step 2, the molar ratio of the amount of lithium hydroxide monohydrate to the volume of water is (15 mmol - 20 mmol):30 mL; in Step 2, the molar ratio of lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide to lithium hydroxide monohydrate is 1:1.

[0035] Other steps are the same as those in Specific Embodiments 1 to 4.

[0036] Specific Embodiment 6: The difference between this embodiment and one of Specific Embodiments 1 to 5 is as follows: In Step 2, the stirring reaction time of the mixed solution at 105°C - 110°C is 10 h - 12 h; in Step 2, the volume ratio of acetonitrile to water is (30 mL - 40 mL):30 mL. Other steps are the same as those in Specific Embodiments 1 to 5.

[0037] Specific Embodiment 7: The difference between this embodiment and one of Specific Embodiments 1 to 6 is as follows: In Step 2, the stirring time at room temperature is 20 min - 30 min; in Step 2, the temperature of vacuum drying is 50°C - 60°C, and the vacuum drying time is 12 h - 18 h. Other steps are the same as those in Specific Embodiments 1 to 6.

[0038] Specific Embodiment 8: The difference between this embodiment and one of Specific Embodiments 1 to 7 is as follows: In Step 3, the mass ratio of lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide, lithium hydride, and PVDF-CTFE is (3 g - 4 g):(0.08 g - 0.12 g):(4 g - 5 g); in Step 3, the mass ratio of lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide to the volume of anhydrous N,N-dimethylformamide is (3 g - 4 g):(30 mL - 40 mL). Other steps are the same as those in Specific Embodiments 1 to 7.

[0039] Specific Embodiment Nine: The difference between this embodiment and any one of Specific Embodiments One to Eight is as follows: In Step 3, the stirring reaction time at 45°C to 50°C is 20 h to 24 h; the temperature of the vacuum drying in Step 3 is 40°C to 50°C, and the vacuum drying time is 20 h to 24 h. Other steps are the same as those in Specific Embodiments One to Eight.

[0040] Specific Embodiment Ten: This embodiment is a single-ion polymer solid electrolyte for assembling a lithium metal battery.

[0041] The following examples are used to verify the beneficial effects of the present invention:

[0042] Example 1: A preparation method of a single-ion polymer solid electrolyte is specifically completed according to the following steps:

[0043] I. Preparation of lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide:

[0044] Dissolve 200 mmol of lithium hydroxide monohydrate in 70 mL of acetonitrile to obtain an acetonitrile solution of lithium hydroxide monohydrate; add 100 mmol of 3-chloropropanesulfonyl chloride and 100 mmol of trifluoromethanesulfonamide to the acetonitrile solution of lithium hydroxide monohydrate, cool it to room temperature in an ice-water bath, and then stir and react at room temperature for 20 h. After the reaction is completed, filter the mixture to remove solid substances to obtain a filtrate; concentrate the filtrate using a rotary evaporator to obtain a solid product; dissolve the solid product in 30 mL of dichloromethane, filter off the precipitated salt, and then concentrate the filtrate using a rotary evaporator and vacuum dry it at 50°C for 12 h to obtain a white solid, which is lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide (LICPSI);

[0045] II. Preparation of lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide:

[0046] Add 20 mmol of lithium hydroxide monohydrate to 30 mL of water, and then add 20 mmol of lithium 3-chloropropanesulfonyltrifluoromethanesulfonimide to obtain a mixed solution; stir and react the mixed solution at 110°C for 12 h. After the reaction is completed, filter the mixture to remove solid substances to obtain a filtrate; concentrate the filtrate using a rotary evaporator to obtain a solid product; add 40 mL of acetonitrile to the solid product, stir at room temperature for 20 min, filter, collect and concentrate the supernatant, and finally vacuum dry it at 50°C for 12 h to obtain lithium 3-hydroxypropanesulfonyltrifluoromethanesulfonimide (LIHPSI);

[0047] III. Preparation of a single-ion polymer solid electrolyte:

[0048] Under a nitrogen atmosphere, 3.4 g of lithium 3-hydroxypropanesulfonyl trifluoromethanesulfonimide, 35 mL of anhydrous N,N-dimethylformamide, and 0.1 g of lithium hydride were added to a 100 mL round-bottom flask and mixed evenly to obtain a mixed solution. 4.8 g of PVDF-CTFE (polyvinylidene fluoride-chlorotrifluoroethylene copolymer) was added to the mixed solution, and then the mixture was stirred and reacted at 50 °C for 24 h. After the reaction, the mixture was filtered to remove solid substances, and a filtrate was obtained. Water was poured into the filtrate for phase inversion to obtain a reaction product. The reaction product was washed with acetonitrile and then vacuum dried at 50 °C for 24 h to obtain a single-ion polymer solid electrolyte (PVDF-CTFE-LIHPSI), abbreviated as PCL.

[0049] Nuclear magnetic resonance tests were performed on the structures of 3-chloropropanesulfonyl chloride, LICPSI prepared in Step 1 of Example 1, and LIHPSI prepared in Step 2 of Example 1. Deuterated dimethyl sulfoxide was selected as the test solvent, and the test results are as Figure 1 shown;

[0050] Figure 1 is the 1H NMR spectrum of 3-chloropropanesulfonyl chloride, LICPSI prepared in Step 1 of Example 1, and LIHPSI prepared in Step 2 of Example 1;

[0051] By comparing Figure 1 the H-NMR results of the three compounds a, b, and c in 2 , it was found that as the electronegativity of the group connected to the -CH 2 group changed, the chemical shift also changed accordingly. This observation indicates the successful synthesis of LIHPSI because the chemical shift shown in its H-NMR spectrum has changed, which is consistent with the expected results.

[0052] Figure 2 is the infrared spectrum of PVDF-CTFE, LIHPSI prepared in Step 2 of Example 1, and PVDF-CTFE-LIHPSI prepared in Step 3 of Example 1;

[0053] PVDF-CTFE-LIHPSI prepared in Step 3 of Example 1 was achieved by performing a Williamson reaction between the lithium salt LIHPSI with an -OH group and PVDF-CTFE with a halogen -Cl group. In this reaction, -Cl reacts with -OH to form a C-O covalent bond. This synthesis method not only effectively connects LIHPSI and PVDF-CTFE but also ensures the stability and performance of the polymer.

[0054] According to Figure 2 the Fourier transform infrared (FT-IR) spectroscopic analysis shown, the characteristic vibration peak of the -OH group was observed at 3438 cm -1, and the characteristic vibration peak of C-O is located at 1073 cm -1 . It is worth noting that in the FT-IR spectrum recorded by PVDF-CTFE-LIHPSI, we can observe the vibration peak of C-O, while the -OH group is transformed during the grafting reaction, resulting in the absence of the characteristic peak of -OH in the spectrum. This result indicates the successful grafting of LIHPSI onto PVDF-CTFE. This conclusion further verifies the conclusion about the synthesis of LIHPSI in the previous text.

[0055] Assemble the SS||PCL||SS battery:

[0056] Place the negative electrode cell case, shrapnel, stainless steel gasket, electrolyte membrane, stainless steel gasket, and positive electrode cell case in sequence in the glove box, and encapsulate them using a battery encapsulation machine. Immerse the PCL electrolyte prepared in Example 1 in propylene carbonate at 60 °C for 1 h; the cell case is of type 2032.

[0057] Test its impedance value through VMP, and the obtained Nyquist plot is as Figure 3 shown, and calculate the ionic conductivity of the electrolyte according to the test results. The thickness of the polymer electrolyte membrane is 58 μm, the impedance is 24.9 Ω, and the obtained ionic conductivity is 1.32×10 -4 S·cm -1 .

[0058] Assemble the Li||PCL||SS battery:

[0059] Place the negative electrode cell case, shrapnel, stainless steel gasket, lithium sheet, electrolyte membrane, stainless steel gasket, and positive electrode cell case in sequence in the glove box, and then encapsulate them using a battery encapsulation machine; immerse the PCL electrolyte prepared in Example 1 in propylene carbonate at 60 °C for 1 h; the cell case is of type 2032, and the diameter of the lithium sheet is 12 mm.

[0060] The electrochemical stability of the PCL electrolyte was studied by linear sweep voltammetry (LSV), and the test results are as Figure 4 shown; at room temperature, a rather flat current response was observed at the initial stage, indicating that the system is in a relatively stable electrochemical state at this temperature. However, at about 4.71 V, a continuous increase in current occurred, suggesting that a continuous oxidation process is taking place. This phenomenon may be related to the oxidation of the solvent propylene carbonate or the polymer itself. Propylene carbonate is a commonly used organic solvent with certain oxidizing properties, and when the voltage increases, propylene carbonate may undergo an oxidation reaction. In addition, the polymer itself may also undergo an oxidation reaction under high voltage conditions, resulting in an increase in current.

[0061] Assemble the Li||PCL||Li battery:

[0062] Place the negative electrode battery case, shrapnel, stainless steel gasket, lithium sheet, electrolyte membrane, lithium sheet, stainless steel gasket, and positive electrode battery case in the glove box in sequence, and then use a battery encapsulation machine for encapsulation; soak the PCL electrolyte prepared in Example 1 in propylene carbonate at 60 °C for 1 h; the battery case is of the 2032 type, and the diameter of the lithium sheet is 10 mm.

[0063] The lithium ion transference number (t Li+ ) plays an important role in the charge and discharge of lithium batteries. A high t Li+ can reduce the concentration polarization of the battery and inhibit the adverse reactions of anions on the electrode, thereby improving the battery performance in practical applications. t Li+ is mainly determined by the measurement method combining the chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). Figure 5 Shows the chronoamperometry curve of PVDF-CTFE-LIHPSI (PCL electrolyte) prepared in Step 3 of Example 1 and the Nyquist plots before and after polarization. Combining with the formula, the calculated t Li+ is 0.90, which fully proves its single ion conduction behavior.

[0064] Assemble the Li||PCL||LFP battery:

[0065] Place the negative electrode battery case, shrapnel, stainless steel gasket, lithium sheet, electrolyte membrane, positive electrode sheet, and positive electrode battery case in the glove box in sequence, and then use a battery encapsulation machine for encapsulation. Soak the PCL electrolyte prepared in Example 1 in propylene carbonate at 60 °C for 1 h; the battery case is of the 2032 type, the diameter of the lithium sheet is 14 mm, and the diameter of the positive electrode sheet is 12 mm.

[0066] Figure 6 Shows the rate performance of the Li||PCL||LFP battery at room temperature; here, 1C is defined as 170 mA·g -1 (considering the average active material mass loading ≈ 3.0 mg·cm -2 , which is equivalent to a current density of 0.51 mA·cm -2 ), which means that the discharge / charge rates of 0.1C, 0.2C, 0.3C, 0.5C, 1C, and 2C correspond to current densities of 0.05, 0.10, 0.15, 0.25, 0.51, and 1.02 mA·cm -2 respectively; at 0.1C, 0.2C, 0.3C, 0.5C, 1C, and 2C, the discharge specific capacities of the battery are 156.42, 150.13, 145.29, 137.18, 117.34, and 78.63 mAh·g -1The decrease in the discharge specific capacity of the battery at 2C is due to the increase in current at high rates, which enhances the polarization effect and leads to a decrease in the lithium-ion diffusion rate. When the rate is restored to 0.1C, the battery capacity recovers to 156.42 mAh·g -1 , indicating that the electrolyte has excellent structural stability and electrochemical stability.

[0067] The Li||PCL||LFP battery was cycled 190 times at a current of 0.5C, Figure 7 showing the cycling performance of the battery at room temperature. The battery showed a fairly stable specific capacity with no significant decay. This indicates that the interface between the electrode and the electrolyte is stable, and the PCL electrolyte has excellent long-cycle performance.

Claims

1. A method for preparing a single-ion polymer solid electrolyte, characterized in that The preparation method is specifically completed according to the following steps:

1. Preparation of lithium 3-chloropropanesulfonyl trifluoromethanesulfonyl imide: dissolving lithium hydroxide monohydrate in acetonitrile to obtain an acetonitrile solution of lithium hydroxide monohydrate; adding 3-chloropropanesulfonyl chloride and trifluoromethanesulfonamide to the acetonitrile solution of lithium hydroxide monohydrate, cooling to room temperature in an ice-water bath, stirring and reacting at room temperature for a period of time, filtering the mixture after the reaction, removing solid matter, and obtaining a filtrate; concentrating the filtrate using a rotary evaporator to obtain a solid product; dissolving the solid product in dichloromethane, filtering off the precipitated salt, concentrating the filtrate using a rotary evaporator, and vacuum drying to obtain a white solid, namely, 3-chloropropanesulfonyl trifluoromethanesulfonyl lithium imide; 2. Preparation of 3-hydroxypropanesulfonyl trifluoromethanesulfonyl imide lithium: Adding lithium hydroxide monohydrate to water, and then adding 3-chloropropanesulfonyl trifluoromethanesulfonyl lithium imide to obtain a mixed solution; stirring the mixed solution at 105° C. to 110° C. for a period of time, filtering the mixture after the reaction is completed, removing solid matter, and obtaining a filtrate; concentrating the filtrate using a rotary evaporator to obtain a solid product; adding acetonitrile to the solid product, stirring at room temperature for a period of time, filtering, collecting and concentrating the supernatant, and finally vacuum drying to obtain 3-hydroxypropanesulfonyl trifluoromethanesulfonyl lithium imide; 3. Preparation of single-ion polymer solid electrolyte: In a nitrogen atmosphere, 3-hydroxypropanesulfonyl trifluoromethanesulfonyl lithium imide, anhydrous N, N-dimethylformamide and lithium hydride are mixed evenly to obtain a mixed solution; PVDF-CTFE is added to the mixed solution, and then stirred at 45°C to 50°C for a period of time. After the reaction is completed, the mixture is filtered to remove solid matter to obtain a filtrate; water is poured into the filtrate for phase conversion to obtain a reaction product; the product is washed with acetonitrile and then vacuum dried to obtain a single-ion polymer solid electrolyte.

2. The method for preparing a single-ion polymer solid electrolyte according to claim 1, characterized in that The volume ratio of the amount of lithium hydroxide monohydrate described in step 1 to acetonitrile is (150mmol-250mmol):70mL; the volume ratio of the amount of 3-chloropropanesulfonyl chloride described in step 1 to acetonitrile is (80mmol-120mmol):70mL.

3. The method for preparing a single-ion polymer solid electrolyte according to claim 1, characterized in that The volume ratio of the amount of trifluoromethanesulfonamide described in step 1 to acetonitrile is (80mmol-120mmol):70mL; the stirring reaction time at room temperature in step 1 is 18h-20h.

4. The method for preparing a single-ion polymer solid electrolyte according to claim 1, characterized in that The volume ratio of dichloromethane to acetonitrile described in step 1 is (30mL-40mL):70mL; the temperature of vacuum drying described in step 1 is 40°C-50°C, and the time of vacuum drying is 12h-18h.

5. The method for preparing a single-ion polymer solid electrolyte according to claim 1, characterized in that The volume ratio of the amount of lithium hydroxide monohydrate described in step 2 to water is (15mmol-20mmol):30mL; the molar ratio of lithium 3-chloropropanesulfonyl trifluoromethanesulfonyl imide described in step 2 to lithium hydroxide monohydrate is 1:

1.

6. The method for preparing a single-ion polymer solid electrolyte according to claim 1, characterized in that In step 2, the mixed solution is stirred at 105° C. to 110° C. for 10 h to 12 h; the volume ratio of acetonitrile to water in step 2 is (30 mL to 40 mL): 30 mL.

7. The method for preparing a single-ion polymer solid electrolyte according to claim 1, characterized in that The stirring time at room temperature in step 2 is 20 min to 30 min; the vacuum drying temperature in step 2 is 50° C. to 60° C., and the vacuum drying time is 12 h to 18 h.

8. The method for preparing a single-ion polymer solid electrolyte according to claim 1, characterized in that The mass ratio of 3-hydroxypropanesulfonyl trifluoromethanesulfonyl imide lithium, lithium hydride and PVDF-CTFE described in step 3 is (3g~4g):(0.08g~0.12g):(4g~5g); the volume ratio of the mass of 3-hydroxypropanesulfonyl trifluoromethanesulfonyl imide lithium described in step 3 to anhydrous N,N-dimethylformamide is (3g~4g):(30mL~40mL).

9. The method for preparing a single-ion polymer solid electrolyte according to claim 1, characterized in that The stirring reaction time at 45°C to 50°C in step 3 is 20h to 24h; the vacuum drying temperature in step 3 is 40°C to 50°C, and the vacuum drying time is 20h to 24h.

10. Use of a single-ion polymer solid electrolyte prepared by the preparation method according to claim 1, characterized in that A single-ion polymer solid electrolyte is used to assemble lithium metal batteries.

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